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1 GEOLOGICAL SURVEY OF INDIA ENGINEERING DIVISION Draft STANDARD OPERATING PROCEDURE FOR DRILLING OPERATION prepared by Engineering Division

Sop Drilling Peer Reviewed

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GEOLOGICAL SURVEY OF INDIA ENGINEERING DIVISION

Draft

STANDARD OPERATING PROCEDURE FOR DRILLING OPERATION

prepared by Engineering Division

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CONTENT Page No

I. INTRODUCTION 3

II. SOP-1: Drilling Proposal for Project Initiation 3 III. SOP-2: Selection of Drilling Technique, Equipment, Accessories 6 III. SOP-3: Resource Planning 15 IV. SOP-4:Mobilisation (Camp Establishment & Site Preparation) 20

V. SOP-5:Drilling and Safety Procedure 22

VI. SOP-6: Drilling Fluids 33

VII. SOP-7: Core Recovery and Preservation 38

VIII. SOP-8: Post Drilling Activity (SPT) 40

Annexures: IA - Drilling Requisition Proposal 43 IB - Geo-Technical Plan 44 II - Proforma for bit record 45 IIIA - Kit Allowance 46 IIIB - Inventory required for a borehole 47 IV - Agreed Staffing norms 48

V - Peer Review Report of SOP 50

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Introduction: Drilling of hole in the earth crust is the most effective means of prospecting for exploration of mineral deposits. Drilling is equally important for Engineering Geology, Geochemical and Geo-Technical investigations. The main activities of Geological Survey of India are-

1. Geological Mapping. 2. Mineral and Energy Resource Assessment which includes ferrous and nonferrous

minerals, base metals like Lead, Zinc, precious metals e.g gold/silver/diamond,, coal and lignite etc.

3. Engineering Geology, Geochemical and Geo-Technical investigations. 4. Geological hazard studies like landslides, earthquakes, arsenic and fluoride contamination

in water etc It is noteworthy that Drilling Division (now called Engineering Division) is categorized as special Function Division and is integral part of survey work done by G.S.I Engineering Division of GSI is engaged in primarily core drilling activities with various gravity feed, hydraulic feed and hydrostatic drills in different parts of the country. The advantage of core drilling is the recovery of representative sample in the form of core. The exploratory holes can be mapping holes, reconnaissance holes, exploration holes for mineral reserves, stratigraphic holes etc. To undertake deeper drilling beyond 900 mts of depth GSI would require additional trained technical personnel, supervisory officers, modern equipments and continuous and adequate flow of fund. In view of the liberalization and the expertise available with GSI, it may have to take up commercial projects for exploration of mineral and precious metals. The commercial projects especially in the field of Geo-technical investigations and iron ore exploration have huge potential and GSI can benefit a a lot by taking up these projects. Investigation by drilling is a preliminary prerequisite and precise method for geological assessment of the ore deposit. It is usually resorted to only when preliminary geological studies like mapping, geophysical surveys etc.indicate probability of deposits in a particular area. The accuracy of data generated by drilling is the most important factor in predicting the reserves correctly. Drilling is a field based activity and is carried out throughout the year. The set up of a drilling camp is quite large due to large amount of stores/machineries/vehicles that are required to be kept in field for smooth drilling operation. The camp office maintained in the field keeps track of all the records and also communicates with HQ. The purpose of this SOP (08 for complete drilling operation) is to ensure acceptable consistent drilling procedure for collecting cores obtained during drilling activity. The SOP procedure applies to the drilling done by Geological Survey of India. S.O.P-1:‘DRILLING PROPOSAL’ FOR PROJECT INITIATION Mineral exploration being done by Geological Survey of India for ascertaining the reserves of the minerals is on regional basis. Following the surface geological work of mapping and geological, geophysical and geochemical inputs wherein promising mineral occurrences are anticipated, a drilling program is initiated to gain knowledge on the continuity of ore and to establish the quality of mineral deposit. Drilling becomes necessary for detailed exploration. Based on the above inputs, a fair geological map depicting lithology, structure, altitude the program of drilling in an area is finalized by the geologist with quantum of drilling, number of holes, location and the tentative depths of the borehole. The basic information about the area and the tentative litholog is required which may be submitted by the Area Geologist to the executing division. The ‘Drilling Requisition Proposal’

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may be submitted in the proforma as per Annex-1A. This provides basic information about the area, its accessibility, tentative litholog, drilling/coring requirements, borehole co-ordinates MSL heights etc. Based on the above data the drilling division has to assess the feasibility of operation vis-a vis the resources it has and has to prepare a tentative Geo Technical Plan (GTP) for each borehole of the project. The tentative Geo Technical Plan (GTP) is to be prepared in the proforma as per Annexure-IB. However, since the drilling undertaken by GSI involves unknown formations in virgin areas, the GTP can be modified as and when required depending upon formations encountered and the drilling condition. The standardization of drilling accessories is very important. The importance of standardization can be summarized as follows. 1.Interchangeability of different component of an assembly. 2.Understanding the common language between the manufacturer and the user 3.To facilitate the producers to manufacture the equipment in advance to enable them to supply on demand. 4.Rationalisation of inventories to get overall economy. 5. Development of mutual trade between different countries. Different standards prevailing in the international market are: 1 DCDMA((Diamond Core Drilling Manufacturers Association) 2.BSI(British Standard Institution) 3.CDDA(Canadian Diamond Drillers Association) 4.ADDA(Australian Diamond Drillers Association) 5.SACDA(South African Core Drillers Association) The above standards merged together and brought out as a common standard for Diamond Core Drilling Equipment known as a) International Standard ISO/DIS/3551/1 System ‘A’ Part-1 The accessories that are used in GSI are- Drill Rods AW(43.6mm) BW(53.9mm) NW(66.6mm) HW(88.9mm) Casing(Flush Coupled)

AX (57.1 mm)

BX (73.0 mm)

NX (88.9 mm)

HX (114.3 mm)

PX (138.6 mm)

Core Barrel (G Series) (M Series) (T Series)

AWG AWM (46.0mm) AWT (46.3)

BWG BWM (57.9 mm) BWT (58.7)

NWG NWM (73.8 mm) NWT (73.8)

HWG HWM (97.9 mm) HWT (96.8)

b) International Standard ISO/DIS/3551/1 System ‘B’ Part-1 (Craelius metric standard developed by merging Swedish and other European countries standards) The accessories that are used in GSI are- Drill Rods 42 mm 50 mm 60 mm Casing 74 mm 84 mm 98 mm 113 mm 128 mm Core Barrel 76 mm 86 mm 101 mm 116 mm 131 mm

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c) COMECON Standard(Metric series developed by merging Soviet block countries standards) The accessories that are used in GSI are- Drill Rods 42 mm 50 mm 60.3 mm 63.5 mm Casing 89 mm 108 mm 127 mm 146 mm 168 mm Core Barrel 89 mm 108 mm 127 mm 146 mm 168 mm In different times GSI purchased drills from different countries and this way different types of standard are in vogue in GSI e.g Russian, Longyear, Craellius, Swedish in regions resulting in wide range of inventories of rods, casings, core barrels, diamond tools etc. This results in high cost of inventory. Standardization of inventory items like rods, casings, core barrels, bits to be used for:

• Coal & Lignite drilling-by diamond core drilling methodology or by Non core drilling for faster penetration in non interested zone

• Metalliferous drilling techniques • SPT and Auger drilling technique

This procedure may take time but once introduced it will reduce the cost of inventory considerably as also effective utilization of inventory of one unit when idle by another drill. Procurement of items will also be easy:

• Instead of small quantities of large number of items(different types/series of diamond tools, core barrels, rods, casing etc), the requirement will be large quantity of fewer items involving healthy participation of reputed companies instead of only a few company monopolizing the business.

It is suggested that GSI may constitute a committee or a Task Force to go into the requirement of drills and accessories and suggest for standardization of drilling items with detailed specification, material composition and physical properties and ultimately go for standardization of the items after discussion with Bureau of Indian standards based on GSI needs. S.O.P-2: SELECTION OF DRILLING TECHNIQUE, AND DRILL ACCESSORIES Once the duly filled Drilling Requisition Proposal is received from the Area-Geologist, selection of suitable drilling technique, drilling fluids, machineries (rigs, pumps etc) and accessories are done. Six drilling methods are widely used, each depending on the type of information required and nature of strata to be drilled. The chain of events in a drilling job has to be carefully planned. Efficient performance of many of the events depends on satisfactory completion of other activities and ultimately successful completion of the job. Along with the GTP, the job profile should have the following data: Job instruction-data-plant selection-equipment selection-shifting to drill site-setting up of equipment-drilling-collect information-samples and data generation-hole completion-providing support to Geophysical logging-shifting to new drill site-timely submission of reports and returns(Fortnightly/monthly and others) (a) Air-Rotary Drilling- This is a quick and economical method of producing a sample. Compressed air is forced down the drill pipe and when it returns to the surface it carries rock chips produced by drilling bit. This method is used in soft rock up to 25 mts depth or to drill through the top layer of decomposed rock and soil to get fresh rock sample of bed rock below.

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(b) Air Percussion Drilling- This method is used for penetrating hard rock to a depth around 300 mts. In this method in stead of rotating bit, hammer bit is forced through the rock by compressed air. Rock chips are carried to the surface by return air. (c) Mud Rotary Drilling- This method is used for drilling through soft rocks, sand and clay layers especially in exploration for coal, lignite, oil and gas. A special mix of clay and water is forced down the hole through the drill pipes fitted with bit. The return mud carries the rock samples in the form of small chips. The method is used for deep holes upto 3000 mts and can be done from ships or offshore platform especially for oil and gas exploration. A mud logger is used to identify the chips. (d) Diamond Core Drilling-In this method a coring bit connected in the core barrel is used for drilling. The core gets collected in the barrel which is recovered after completion of the run. The core collected gives information about the rock types and information about the various layers of rock. Diamond Core Drilling is mostly used in Geological Survey of India. Surface set and impregnated diamond bits are used for core drilling operation. The bit record is maintained at the site in the enclosed proforma as Annex-II

RD-100 Drill in operation at site (e) Dry Drilling- Dry drilling using TC tipped cutting tools at low r.p.m is useful where use of any drilling fluid results in loss of core. It is not possible to do dry drilling in hard rock formation as the heat generated will be too high to be sustained by the string.

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(f) Auger Drilling- This method is used for Seismic Exploration, Engineering Geology, Hydrology Survey and prospecting. Hand augur drilling is normally done for getting soil samples up to 2-3 mts depth. Machine driven augurs can go up to 50 mts depth. The only limitation in this type of sampling is that undisturbed samples can’t be obtained. Augur drilling is effective in soft and medium hard formation and also in weakly cemented pebbles. The suitable drilling technique is selected depending upon the depth and size of the borehole, mineral to be investigated, sampling requirements and nature of formation. Conventional core drilling is used for shallow to medium depths in difficult clayey and fractured formation.Wireline drilling is used for deep holes with consolidated formation. When representative soil samples are required SPT techniques as per S.O.P-8 is used in general using Split Spoon Sampler device preferably with self tripping assembly. Dry drilling can provide uncontaminated core but is suitable for shallow holes only. Selection of drilling method is also determined by the availability of proper equipment and accessories. Selection of drilling fluid depends on nature of formation and is discussed in SOP- 6 on Drilling fluids. Selection of methods of drilling is also affected by availability of equipment and relevant standardized series accessories Selection of Drill- The selection of drill depends on following factors.

1. Borehole depth- The proposed depth and size of the borehole are the guiding factor for the selection of the drill. The capacity of a diamond core drill is based on its capacity to lift the drill string.

The capacity of drill (HP) = W (weight) x V(velocity) x n 100 W- Weight of string with extra 20% for frictional losses as per DCDMA standards. V- Hoisting speed in meters per minute n- Efficiency. The power consumed by the auxiliaries is around 20 % and so the required capacity of

the drill is to be increased by 20%.

2. Character of rock-The character of rock determines the speed and feed requirement. The drillability depends mainly upon formation hardness and toughness. Hard formations require hydraulic feed rigs.

3. Terrain condition- In difficult and hilly terrain light weight rig and pumps are preferred.

In GSI for depths below 300 mts drill model RD-30, RD-60,DM-625 are used, for depths between 300-600 mts Vol-300, GD-60S, IBA-15H and for depths beyond 600 mts RD-100, BRGM-TP125 are used

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Truck Mounted Drill Selection of Drilling Fluid- Selection of drilling fluid mainly depends on the type of formation and the borehole depth. The various kinds of drilling fluid used in GSI are water, bentonite mud, cutting oil and polymers (both water and mud based)

1. Water- It is freely available fluid and is primarily used in core drilling operation. It has very good cooling properties and acts as moderate lubricant and vibration dampener

2. Bentonite Mud- This increases the viscosity and gives better cleaning of the hole. It acts as very good lubricant and also reduces the vibrations in the string considerably. It forms cake on the borehole walls and thus protects the caving in the borehole. Bentonite mud solution has gelling properties and thus it keeps the cutting in suspension even the circulation is stopped.

3. Polymer- The polymer has similar properties as that of bentonite mud except gel strength. It has excellent flushing capacity. The only draw back is that circulation is to be maintained all the time else the cuttings will quickly settle at the bottom any jam the string. The preparation of mud, its properties, measurement and control has been discussed in S.O.P- 6 on drilling fluids.

Selection of Pump- In diamond drilling operations the fluid requirement is basically of low flow rate and high pressure. These requirements are best met by reciprocating pumps. These pumps are capable of delivering constant discharge at various heads. The replaceable liners provide

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extra flexibility for different discharge and pressure. The reciprocating pumps used in drilling can be of duplex/triplex single acting or double acting depending upon the head and discharge required. For shallow boreholes and in hilly areas where water is used as drilling fluid, smaller pumps are used. Duplex double acting pumps are used wher mud is used as fluid. For deep boreholes ie drilling for Coal/CBM etc RD-900, FM-45, RD-395, Vol 6x6 etc are used. The return water velocity should be in the range of 30-50 mts per minute for good flushing of the borehole. It depends on the annular space between the string and the wall which changes at different depths due to telescopic holes, rheological properties, viscosity and density of cutting etc. The return velocity has to be such that it does not erode the borehole walls, wash out the core and at the same time lift the cuttings

RD-395 Mud Pump in operation at site Approximate Return velocity for various bits. Sl No

Type of bit Return velocity with water in mts per minute

Return velocity with bentonite mud in mts per minute

1. Rock Roller bits in hard rock 40-60 25-40 2. Tungsten carbide bits 20-35 15-30 3. Diamond Bits 35-50 25-45 The pressure of fluid under delivery is another factor in selection of the pump. The pump delivery pressure has to compensate for various losses in the joints, valves, wall friction etc. On an average the pressure requirement is 14 kg/sq cm for every 225 mts of borehole depth for conventional drilling and lesser for wire line drilling. The approximate discharge required for NW rod with matching barrel is 8 US gallons per minute. The selection of pump is based on pressure and the discharge required for better flushing of the hole.

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Selection of bit- The selection of bit mainly depends on the type of formation to be drilled and the acceptable core size. Surface set diamond bit and impregnated diamond bits are generally used in GSI. The other features of the bit like carat loading, kerfs area, no of water ways and design are governed by rotational speed, type of drilling fluid, thrust applied on the bit etc. GSI is mostly engaged in diamond core drilling either by conventional or by wire line method.

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A general chart showing the broad guidelines for selection of surface set diamond bits is given below. Sl No Type of formation Diamond

Size(SPC) Matrix

1. Very soft-Talc, Bauxite 4/7 Hard 2. Soft-Gypsum, Coal etc 10/25 Hard 3. Medium Hard- Dolomite

Flourite 15/25 Hard

4. Hard- Apatite, Soft Granite 25/40 Hard 5. Hard(Solid)- Fine Gneiss 40/60 Hard 6. Very Hard(Solid)- Quartz 60/80 Hard 7. Very Hard(Broken) 80/110 Hard Now a day’s synthetic diamond bits and poly crystalline diamond bits which give better meterage at relatively lower bit cost are being extensively used in place of surface set bits by other organizations. In GSI also such bits are being introduced on experimental basis. It is imperative that for better productivity core bit/reamer shell/barrel should be of one standard series. This also stabilizes the borehole. Selection of Core Barrel- Selection of proper core barrel is the most important factor in achieving good core recovery which is the ultimate aim of core drilling. The core barrel in its various forms is a tubular piece of equipment which houses the core as it is cut and holds it till the string is retracted from the hole for removal and storage of core. When drilling the barrel is located directly above the core bit and reamer shell. Rotation and feed are applied from the machine through the drill string, barrel and reamer shell to the bit. In Geological Survey of India DCDMA and Swedish standard core barrels are mostly used. Single tube and double tube core barrel are generally used. In hard compact formation single tube barrel performs well. It is strong and can withstand the heavy feed pressure required to penetrate hard formations. It offers good core recovery and trouble free operation. The double tube swivel type core barrel has two tubes, one inner and other outer tube. The inner tube is suspended from the barrel head by bearings. The drilling fluid passes between the two tubes leaving the core un-exposed to the drilling fluid except for the few centimeters as it passes through the reamer shell and the bit. Selection of Drill Rod & other Equipment- Requirement of different sizes of drill rod depends on the size of core barrel used and therefore size of the borehole to be drilled. For a larger size borehole use of bigger size rod is recommended to reduce vibration, maintain stability of drill string, better weight distribution on bit and to attain optimum r.p.m for maximum drilling rate. Six sizes of drill rod are in use in GSI ranging in size from 27.8 mm to 89.1 mm OD. Two designs of drill rod are in use (1) Parallel wall (2) Upset end and forged. For smaller sizes(RW to AW) where torque transmission requirement is low, both parallel wall and upset end rods are used whereas for sizes from BW to HW only upset end rods are recommended as the ends are strengthened by forging to withstand higher torque transmission and avoid failure of joints. However, BW parallel wall rods are now being put into use considering cost and easy availability. The drill rods are made from En-8 grade of steel and are cold drawn seamless tubing to ensure smooth surface finish and close dimensional tolerances, uniform metallurgical structure throughout the cross section. The rod couplings are made from En-19 to provide better strength

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at joints. The drill rods are heat treated by tempering to achieve toughness while still maintaining the hardness. The essential requirement of good quality drill rods are-

1. Proper material with desired mechanical properties 2. Smooth surface, uniform wall thickness throughout the cross section 3. straightness should be 1 in 1200 4. Threads should be perfectly matching with coupling threads.

For wire line drilling drill rod and core barrel from BQ (55.6mm) to HQ (88.9 mm) are generally used. The derrick is selected on the basis of the required depth of the hole. For shallow holes of around 300 mts depth, Tripod is used whereas for deeper holes 4 leg steel derrick constructed by angles and channels to provide sufficient strength are preferred. The rod pull of the derrick is usually 20 feet.

Four leg Derrick at drill site

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The BRGM and IBA-15H drill have in built mast and so errection of separate derrick is not needed. All modern drills are truck mounted with inbuilt mast in it. This saves lot of time in dismantling and errection. There are a number of other accessories like foot clamp, water swivel, fishing tools etc that are required for drilling operation. S.O.P-3: RESOURCE PLANNING (a) Man Power Requirement- The Engineering Division at Regional Head Quarter is headed by J.A.G level officer(Director/Superintendent Engineer), the S.T.S level officers(Drilling Engineer(Sr.)/Executive Engineer) who functions as Project-in- Charge of field units and also acts as the interface between field and HQ The field establishment in drilling is usually headed by a D.E (Jr)/Driller rank officer. He is assisted by STA (D)/JTA (D)/DA etc in the field. At present Drilling Division is facing acute shortage of trained manpower (both officers and staff). The actual strength in Group ‘A’ & ‘B’ including the E & T personnel as on date is only 76 against the 150 sanctioned posts. Out of 76 operational drills as many as 46 drill units are headed by Group ‘C’ non gazetted staff due to shortage of supervisory officers in the grade of Driller/D.E (Jr). Immediate recruitment in the grade of Driller/D.E (Jr) should be done. The Staff Inspection Unit (S.I.U) constituted in 1964 under the Department of Expenditure, Ministry of Finance with the object of effecting economy in manpower consistent with administrative efficiency and evolving performance standards and work norms in Government offices. The staffing norms for deployment with drilling rigs have already been reviewed by S.I.U in 1983. According to these norms there should be 12 drilling crews against each drilling rig having capacity more than 550 mts and 10 for rigs of capacity less than 550 mts. The above norms does not exclude engagement of contingent workers for specialized skilled jobs(Technical helpers at drill site), semi skilled jobs(Pump/Generator attendant) apart from un-skilled workers required for watch and ward duty.In the present context also for efficient operation of rig on two shift basis, the strength as envisaged is required to be maintained. The agreed staffing norms are enclosed as Annex- IV. To overcome the shortage of field operators, the possibility of hiring the contingent workers on contract basis who can run the machine has to be explored. As modern technology is creeping in ,GSI technical personnel are to be continuously exposed to the development of the industry(drilling technology, mud technology, modern management concepts etc) (b)Office Equipment, Camp Equipments and Tools- Each drilling camp has to keep an office for maintaining various records and preparing reports and returns. It has to maintain a large number of Stock Ledgers(of capital equipments, non consumable drilling accessories and equipment, miscellaneous consumables, GI stock ledger, diamond bit register, TC bit, spares register, POL ledger, camp equipment etc), History Sheets and Running Log Books, Cash Books, files and reports for record. The following reports are prepared and submitted to HQ fro drilling units. 1. FDPR(Fortnightly Drilling Progress Report) 2. SMR(Secretary Monthly Report) 3. POL monthly expenditure report 4. MDER(Monthly Drilling Establishment Return)

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5. Costing Report 6. Monthly Bit Performance Report 7. Other reports of non periodic nature like Survey Report, APR and ADR. These reports are generated in the drilling camp for monitoring of the expenses, performance review and for quality checks. This require a camp office equipped with all modern communication facilities like computer with internet, mobile phone etc. The provision of tentage as per the details is required for the establishment of drilling camp. (i) For Gazetted officers: 1 ‘L’ tent, 2 ‘S’ tent and 2 ‘N’ tent (ii)For non Gazetted personnel: 1 ‘O’ tent, 2 ‘S’ tents and 2 ‘N’ tents Besides tentages at least 500 corrugated GI sheets are required for erecting Camp Office, POL , Store and Garage shed. At least 3 heavy duty steel racks, 2 steel almirah and 2 bit box are required for keeping drilling accessories, office records and diamond bits respectively.

Or Pre-fabricated hutments are now easily available in the market under DGS&D rate contract. These hutments are portable and have a long life and cheaper in the long run. The pre-fab hutments as per the entitlements should be used for projects having tenure of more than a year. The various other tools required are pick axe, crow bar, earth working hand tools, electrical tools, fittings, welding tools etc. The personal kit requirement for drilling personnel is given at Annex- 3A To further reduce the unproductive time preparation of drill site, approach road repairs, shifting work, construction of temporary hutments should be done on contract basis. The funds should be available all the time and camp in charge should have sufficient financial powers to incur expenditure on such types of work so that the borehole is commenced on scheduled date. (c) Logistic Requirement-The logistic requirement of a drilling unit is as below. (i) One 4 WD long body truck (ii)One 4x4 mini truck (iii) Two 4x4 Jeep (iv)Jeep Trailor and Water Tanker-1 each (v) Communication facilities like mobile phone and computers to field officers to enable them to establish immediate contact with the Area-in-Charge/area Director in case of need. (d)Funds Requirement-The fund is required for movement of truck/jeep with store of the unit, approach road repair, drill site preparation, running of drilling operation, POL, miscellaneous repairs and other contingencies. Before commencing a project, provision for at least 3 months expenditure should be made in advance. The concept of “Deposit Account” has to be evolved for drilling operation which requires consistent flow of funds for continuous drilling. The monitoring of expenditure vis-a -vis progress may be done by Director (D)/Zonal-in-charges. (e) Machineries, Drilling Accessories and Tools-

• Bore holes to be kept slim with suggested minimum reduction in size. • More of wire line drilling to be introduced9at least 80% wire line and 20% conventional) • Improvement in diamond bit technology(introduction of PCD and synthetic bits)

High speed dynamically balanced drilling rigs capable of very high rotational speed around 2000 rpm and introduction of fitting diamond tools(PCD or synthetic diamond bits) is the necessity of

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the day. GSI is in the process of procuring hydrostatic drills of deep capacities(beyond 1200 mts).Reverse circulation drill which are very fast can also be introduced to meet the challenges of the day. The standard requirement for successfully completing a 650 mts borehole within the stipulated time is given in Annex- III B (f) Geo-Technical Plan for Drilling-The Project Plan and Draft Geo-Technical Plan may be prepared by Director (D) in consultation with the Zonal-in-Charges taking into account the available resources and the methodology described in the SOP. It should be prepared on the basis of expected litho log (Annex-IA) furnished by Director (Project). The Geo-Technical Plan should be supported with the proposed borehole sketch showing the details of placement of casings, composition of drill string, the size of core barrel and bits for different depths, mud parameters required for various depths and the expected time required for penetrating different segments of the borehole. The proforma for draft GTP is enclosed (Annex-IB) However, in course of drilling if the formation encountered is different than what was expected or if the Geologist suggests deviation from GTP then the suitable action according to the condition of the hole may be taken by the field -in-charge. Later on the proposed GTP should be modified accordingly in consultation with the field Geologist. The modification in GTP should be recorded and brought to the notice of Director (D). Drilling operation is to be closely monitored by Zonal-in-Charges and is to be periodically reviewed by Director (D) and Director (Project).It is also essential that location of all the boreholes in a area is given beforehand by the Area Geologist for advance planning about the hole. This will also give flexibility to the Driller-in- Charge to prepare difficult inaccessible sites simultaneously while continuing drilling at other site. The geophysical logging should also be done immediately after closure of the hole. The productivity schedule as mentioned below may be considered for planning. Sl No

Terrain/Type of Formation Approved meterage per annum(mts) as per Board of Management, GSI in its 52nd meeting

Remarks

1. Base metal(Peninsular) 800 Double shift basis 2. Base metal(Himalayas) 500 Single shift only 3. Coal & Lignite 1100 Double shift basis 4. Dolomite/Limestone(Meghalay) 800 Double shift basis 5. Geothermal Drilling 500 Single shift only 6. Dry Drilling(Mn & Chromite) 500 Double shift basis 7. Dry Drilling(Bauxite) 650 Double shift basis 8. N.E States(except Meghalaya) 500 Single shift only

The norms per annum have been fixed for drilling per rig under two shift operations which is desirable for all kinds of drilling to achieve the target within the prescribed time. The project completion time may be calculated after taking into account the terrain condition, the existing resources, the availability of man power and the past performances. The productivity achieved per shift depends on type of strata to be drilled, type of drilling technology, quality of accessories used, availability of resources (Manpower, Equipment, Logistics and Fund). It is also affected significantly in hill and due to adverse weather conditions etc.

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Wire Line drilling is to be done in all cases where borehole depth is more than 300 meters except in some cases where there is excessive caving and chances of string getting jammed. The average productivity if all the drilling parameters are maintained should be at least 6 meters per shift in soft formations. This will help achieve the drilling target and also complete the borehole within stipulated time. (g) Borehole Planning-The field geologist will provide the tentative depth and the litholog of the bore hole to the Driller-in- Charge. The Driller-in- Charge will plan the bore hole according to the availability of resources and the end core size. Bore hole planning mainly consists of (a) Casing Planning (b) Drilling Planning Casing Planning: Casings are required to be lowered to cover the over burden/ loose strata so

that bore hole can reach up to desired depth. The following points are to be kept in mind while lowering the casing.

(i) Drive Pipe of 168mm or bigger to be lowered up to bedrock or below the water sensitive formation. Its size should be such that biggest size core barrel can pass through it. Usually drive pipe of 6m-9m is lowered in the hole.

(ii) The overburden in the hole should be covered by at least two sizes bigger than the size

of the core barrel e.g 116 mm barrel casing size should be 146 mm. To lower the casing of 146 mm the hole should be drilled by 5 5/8” RR bit. The auxiliary casing should rest on hard rock. It may be omitted if borehole can stand open without casing.

(iii) In case if at deeper depth loose formation is encountered, smaller size intermediate

casing is to be lowered keeping in view the core barrel which is to be used for drilling.

(iv) While lowering the casing it’s outer surface is to be greased for easy removal of the same after completion of the hole.

(v) Usually casing is subjected to whipping action by the drill rod so it has a tendency to

open up during drilling. To avoid this while lowering the joints should be securely tightened and if needed rosin to be used

(vi) For Wire Line Drilling HX/127 mm casing can be used as auxiliary casing and NX can

be used as intermediate casing.

(vii) For shallow boreholes in hard formations drilling can be done by covering only the overburden

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SCHEMATIC DIAGRAM OF CASING PROGRAMMING:

• Surface casing- for covering loose overburden • Intermediate casing-for covering intermediate caving zone • Production casing-necessary for production bore holes • Telescopic sizes of casings in any standard- minimum changes in the borehole size

for smooth and efficient removal of cuttings and maintenance of borehole walls.

Surface casings 168 mm upto 50 mts Conductor casing up to 150 mts of 146 mm Intermediate casing up to 350 mt of 127 mm In case it is required, further casings will be lowered or the bore hole will advance uncased, hole wall being controlled by mud parameters Drilling Planning: Selection of drill rig, pump for drilling operation depends upon the type of drilling, the borehole depths, availability of water sources, terrain condition. The four leg derrick is usually used in GSI for deeper depths. If the desired borehole depth is less than 300 mts then conventional drilling with T-6 or any other barrel of 6 m length is useful. For depths beyond 300 meters depth Wire Line drilling will give better progress. In case of conventional drilling Telescopic hole is to be done to avoid reaming. A 600 meter bore hole can be completed in three sizes namely 116 mm, 101 mm and 86 mm. For depths beyond 600 meters 76 mm barrel can also be used. The standard practice for telescopic borehole is like this:- First 20 % of total depth by 116 mm barrel, next 30 % by 101 mm, next 30 % by 86 mm and remaining 20 % by 76 mm size. For Wire Line drilling only two sizes namely HQ and NQ are used in GSI because of the acceptability of core size. For wire line drilling 40 % of the total depth can be drilled in HQ size and rest 60% in NQ size.

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S.O.P-4: MOBILISATION, CAMP ESTABLISHMENT & DRILL SITE PREPARATION The camp shifting may be within the state or outside the state depending upon the geological program. A suitable camp location is finalized as close as possible to the working area where future boreholes are likely to be located. While selecting the camp location, the basic amenities like availability of water, electricity, transport from near by town, market and dispensary must be taken into account. The other factors that play a crucial role in selecting the camp location are proximity to workshop, availability of POL and communication facilities. If it happens to be a private land an agreement with the land owner is a must. For establishment of camp in a government land necessary approval from local authority is to require before commencement of shifting. The camping ground is to be properly cleaned and leveled, followed by pitching of tentage and erecting of store, POL and vehicle shed. The time required for shifting of camp depends upon the available logistics and is to be taken into account while assessing the project completion time. Shifting of drill unit from one investigation area to the other involves number of activities. The following table gives the standard time required for completion of various activities involved in shifting of drill unit. Sl No Activity Time Allotted

Winding up present establishment viz demobilizing of equipment and machineries, packing and listing of stores, estimating total truck load etc Mobilisation of transport, submission of proposal to Dir(D) and discussion

1.

Allotment of shifting work, the movement of advance party for reconnaissance/preliminary survey.

15 days

Implementing of shifting plan, monitoring of movement of truck, corrective action required in case of break down of vehicle.

2.

Unloading of truck at new area, setting of camp, development of drill site and installation of rig, pump etc at new borehole point

7 days

Based on the current status of transport infrastructure in GSI, No of days required for a round trip and approximate truck loads for different have been worked out in table-I & II Table-I( Estimated time for round trip) Distance up to Plain to Plain Plain to Hill Hill to Hill 200 KM 3 days 4 days 5 days 500 KM 6 days 8 days 10 days 1000KM 10 days 13 days 15 days 1500 KM 14 days 15 days 20 days Above 1500 KM 18 days 20 days 25 days

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Table-II(Estimated requirement of truck load for shifting of drill unit) Sl No Description Drill - 300 mts Drill-600 mts Drill-Above 600 mts 1. Machinery 3 truck loads 3 truck loads 4 truck loads 2. Drill Accessories 3 truck loads 4 truck loads 5 truck loads 3. U/s material 1 truck loads 2 truck loads 2 truck loads 4. Camp equipment 3 truck loads 3 truck loads 4 truck loads

The shifting time as mentioned in Table-I can be reduced to a great extent if private vehicles are hired. If hired vehicles are available, shifting should invariably be done buy it only. It will be economical also as our departmental truck are old and has carrying capacity of 8-10 tons only. Drill Site Preparation (i) The field geologist shows the borehole point to the Driller-in- Charge. Before giving the

point the field geologist has to ensure that the land is free for taking up the borehole. If it happens to be a private land the land owner is to be contacted and an agreement is to be finalized giving the details of the condition for use of the land. If the borehole is on government land, it is to be ascertained whether it falls within the reserved forest area or not and the necessary clearances for drilling in that area exists. The area with overhead electric cables should be avoided.

(ii) The area required for drilling the borehole is roughly 4000-5000 sq ft. The area is to be

cleaned, bushes to be cut and removed, leveling is to be done so that there is no water logging at the site etc.

(iii)Locations for installation of derrick, rig, and mud pump are to be identified. The rig is to be

installed in the direction where there is minimum exposure of sunlight to the crew. The pressure pump should be visible to the crew and as far as possible from the rig.

(iv)The rig and the derrick are to be securely anchored. The anchoring of rig and derrick should

be of RCC. (v) The mud pump should be installed as close to the source of supply as possible .It is also

desirable to set the pump in a light, clean and dry place with adequate space for inspection and maintenance. It should be mounted either on concrete foundation or on rigid metal or wooden frame. While installing pipes and fittings it should be ensured that it is free from dirt and free from leakages. The return line from relief valve should go to the tank directly. The suction line from the source should be as small as possible, bigger in diameter and should slope uniformly to the pit to avoid forming of air pockets. The suction line must have a foot valve. The discharge line should be straight and with minimum joints to avoid pressure loss.

(vi)There should be three pits of 10’x10’x3’ for storing fresh water, return mud from the hole

and the clean mud that is to be pumped in the hole respectively. All the three pits should be plastered using brick and cement to avoid leakage and contamination with the soil. The The return mud channel should be 1’ x 1’ with at least three settling pits of size 2’x2’x2’. The return mud channel should also be plastered with brick and cement. The inlet to the settling pit and the outlet should be at 90 º. Hydrocyclone is to be continuously used to clean the return mud before pumping it into the borehole.

(vii)Tubular are to be stacked above ground and preferably on three supports at the site as well

as in the camp. Ac small store room is to be built at the site to stock essentials items like POL bits etc at the site.

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(viii) Core boxes to be kept at the site all the time. (ix) Genset of at least 5 KVA is to kept at drill site for lighting and extended/two shift operation. (x) Arrangement of vertical stacking of drill rods taken out of the bore hole to be made. S.O.P-5: DRILLING & SAFETY PROCEDURES The following checks are to be done before starting the rig. (i) The site is to be cleaned and machineries de-contaminated before starting of operation. (ii) Checking of oil and water level in the radiator in all the machineries that are to be started

should be done. If found low it should be brought to optimum level. (iii)Mud Pump valves/lines/pressure gauges/safety valve to be checked. Mud agitator is to be

used and it should be started preparing homogeneous mixture of mud. (iv) Other checks related to safety aspects are described in SOP-5 on drilling operation and

safety. (v) Checking of operating and servicing support equipment Core Barrel Fitting:- (a) Core to be recovered from the hole should be least contaminated and should be

representative of the formation being drilled. Double tube swivel tube core barrel of 6 meter length is to be used for better productivity.

(b) Swivel action of the barrel head to be checked. Inner/outer tube is to be joined in the head,

vent hole to be cleaned and swivel head bearing to be lubricated. Hard alloy faced or T.C tipped barrel heads are to be used particularly in hard abrasive formation. This avoids excessive wear of barrel head and maintain correct outer gauge.

(c) Reamer shell/bit/core lifter and case to be fitted in the barrel. (d) The clearance between inner tube and bit at its face should be adjusted to 1.5 mm (e) The straightness of the barrel is to be checked before lowering it in the hole by placing it on

a straight edge. Tightness of threads of bit and reamer shell to be checked. (f) The core lifter when pressed into operation should have sufficient spring action and it should

rotate freely in the case/chamfered wall of the bit. Core lifter and case to be replaced after every 30 meters or when ever if there is core loss due to loosening of core lifter.

(g) Two sets of core barrel of every size are to be used while drilling. To save time the ready

barrel will be lowered in the hole immediately after recovery of core laden barrel from the hole. In case of wire line barrels two sets of inner tube/overshot assembly to be used.

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(h) In case of wire line drilling to save the bit from, the inner tube is to be dropped only when if there is sufficient water in the hole to slow down its movement otherwise it is to be lowered by means of overshot assembly.

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Drilling Operation:- (a) The drill string fitted with double tube core barrel is to be lowered in the hole by hoisting

drum slowly. If the hole is clear the string will move very close to the bottomed depth. There after hoisting plug is to be replaced by heavy duty water swivel and mud is to be pumped for flushing the hole. Once cutting is removed the string will hit the bottom. Mud circulation in the hole is to be continued.

(b) Both hydraulic and mechanical chuck is to be fastened and start the rotation. (c) For broken, hard and unconsolidated formation impregnated diamond bit with soft matrix is

to be used. The size of stones may be kept in the range of 40-50 US mesh and hardness 30-35 RC.The RPM for impregnated diamond bit should not be less than 600. The feed is to be adjusted according to the penetration rate. The bit weight for impregnated bits should be around 15/20 N/sq mm

For medium hard/soft formation surface set diamond bit with SPC in the range of 30/60 can

be used with RPM of around 300-500. Bit weight for surface set bit should be around 40-60 kg/sq cm. The bit weight and the RPM required has to be adjusted depending upon the nature of strata encountered. The graphs below shows recommended r.p.m for various types of bit and effect of bit weight on drilling rate and also the cost.

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(d) Mud pump discharge pressure should be maintained in such a way that the return mud

velocity is around 25-30 metres per minute. A very high velocity will erode the wall and low velocity will not be able to lift the cuttings. Reciprocating pumps are to be run around 200 rpm. Other properties of mud are described in SOP- 6 on drilling fluid.

(e) To remove the cuttings from mud hydrocyclone is to be run continuously as long as drilling

rig operates. (f) After completion of the run, entire drill string is to be retrieved from the hole for recovery of

core. In case of wire line drilling only inner tube is to be recovered and another spare tube is instantly lowered and drilling can be resumed immediately. The details regarding handling of core is described in SOP- 7 on core handling.

(g) Two shift operation is must for all kinds of drilling to achieve the specified targets within the

prescribed time. For borehole depths beyond 750 meters possibilities for continuous operation to be explored

(h) Water flow and pressure are important indicators as to what is happening in the bore hole, in

the formation and in the bit. It also indicates to a certain extent the nature of formation. A sudden surge in pressure indicate blockage at the bit face. These two parameters are to monitored carefully for smooth drilling operation and to avoid fishing.

(j) The tentative requirement of stores for a 650 meters borehole is furnished as ‘Annexure-III B’ FISHING AND FISHING TOOLS Introduction: A drill bit or piece of equipment lost in a borehole is called fish. They have to be recovered from the hole, so that drilling can be continued to complete the hole. The operation of retrieving the lost object is called “Fishing Operation”. An analysis of shift utilization of a drilling project reveals that 15 % of total available shift are lost in fishing and related in hole problems. In drilling each area has different problems and each borehole has its own history. No common rule can be prescribed. In hole problem occur by way of stuck/broken bit, rod, dropping of pieces of equipment, collapse of borehole wall etc. Drilling crew should be fully equipped to deal with the problem. Awell trained driller by his knowledge and experience in the area and with innovative ideas can vastly reduce the time lost in fishing operation. Most of the fishing are due to bit or core barrel broken or unscrewed in the hole, breakage of drill string, unscrewed casings, stuck up drill string or casing due to caving or during drilling, wireline cable breakage, small tool or equipment pieces falling in the bore hole. These are generally due to negligence or oversight on the part of the drill crew, unstable formation causing caving or collapse of the hole, crooked holes of excessive deviations, use of worn out tubular, failure of handling/hoisting equipment, overloading, wrong drilling practices and incorrect handling of tool.

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Fishing operations: Dimension and position of the fish- The first important step is to collect all information relevant to the occurrence of the trouble in the hole and to record correctly the depth, dimension and position of the fish. Often operators allow the drilling to continue few centimeters after the trouble occurred disturbing the shape of the fish and complicating fishing operation. A sincere record of the equipment used when the drill string got jammed or broken will help the driller to plan the fishing operation efficiently. Jarring or Jacking up of stuck drill string or casing-When drill string or casing is stuck in shallow over burden, they can be extracted by back hammering with jar weight. Also jammed drill strings and casings in caving formations are slowly pulled out with heavy duty 50-100 ton twin jacks. The string is held firmly with slips placed in centre hole of twin jacks. Extraction of broken bit or small piece of equipment-This is done with recovery tap if there is core or caving in the hole. Small pieces are retrieved with the help of magnetic extractor or by drilling a short hole with a core barrel with sludge collector on top to collect heavier cuttings. Jammed or broken rod string-The most common failure is jamming and breakage of drill string due to material failure or collapse of the hole. When the string is broken, top broken position of the string is hoisted out and dimension and depth of broken rod inside is noted. The first attempt is to lower rod spear/male tap/bell tap with left hand rods to catch and unscrew damaged top portion and pull it out. The drill string in the hole is connected with drill rods, establish circulation of drilling fluid to wash the cuttings if any and pull the entire string. In case the string is found jammed, efforts may be made to hammer the string upwards with jar hammer and sometimes the jam is loosened with jerks at shallow depths. When this attempt fails, rods are unscrewed with left hand tools as far as possible up to barrel head. The bore hole is then reamed with three or four pieces of casing a size larger than jammed barrel. Casing shoe bits are to be used while reaming around the barrel, reamer shell and bit. After complete reaming string of drill rod is lowered to connect with the barrel and pull it out. When the drill string is severely stuck up and defies prolong attempt to free it, the driller has the following three option. 1.Un screw the string with left hand tool as far as possible, ream the hole to larger size with casing bit(using pilot reamer) .When the jammed objects are freed, connect them with drill string and pull out. 2. Leave the stuck part of the rod in the hole, pull out as many rods as possible and then deflect the hole using wedges. 3. If wireline system is being used, abandon the jammed string in the hole as this in effect becomes the casing and drill through the barrel with next small size and complete the hole. After completion of the hole, most of the jammed string can be salvaged with left hand tools. Commonly used fishing tools-There is no standard fishing tools. The most commonly used fishing tools are- 1. Jar and Jar collar-Jars are 200 to 300 kg hammer with hole at centre and chains for handling. They are used with jar collars for back hammering. They can be used manually or with the help of cathead provided on the drill. 2. Hydraulic jacks- Hydraulic jacks of 50 ton or more capacity are used to pull out stuck string from shallow depth.

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3. Rod spear and friction grip tools-Rod spear is tapered spear with four sharp edges which can take grip of drill rod fish by friction. The advantage of rod spear is that in case if the fish is very tight, it can be disconnected with upward tapping. 4. Magnetic extractor-A powerful permanent magnet is lowered in the hole on wireline cable to extract broken pieces. Surest way cleaning small objects and non magnetic pieces is to drill a mouse hole and recover the core. 5. Recovery taps and dies-These are attached to drill rods and lowered in the hole to grip the fish and when rotated they cut thread on the fish and hold it securely and could be pulled out along with the rods 6.Left hand drill rods and tools for centering fish- To centre the fish spiral grappling type tool is used. 7. Rose bit-Rose bits of different sizes are milling type bits which are used to grind out small pieces of broken bits. Deflection wedges-They are made out of casing to pass the stuck fish in the hole when other attempt to fish out the object fails. Some of the above fishing tools are illustrated below:

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Preventative measures-In diamond drilling operations, it is important to have clean, safe and fluid filled holes for higher bit revolution per minute and faster penetration. Borehole stability is also very essential and can be maintained with proper drilling fluid control. Drill rod and casing failures can be minimized significantly by keeping service record of the equipment, periodical inspection for fractures and wear and replacement of worn out equipment. Bits, reamer shell, core barrel and drill rods have to be checked and serviced after each run. Wireline cable, hoisting cable and rod handling tools to be maintained in good condition. The drill site should be clean and organized. The drill crew and operator should be well trained to follow good drilling practices. They should be able to visualize what is happening in the hole, anticipate problems and efficiently deal with them. Innovative methods may have to be employed to deal with different situations as they occur. Almost any fishing problem can be solved if sufficient time and funds are available. The driller must be aware of the economics of continuing non productive fishing operation. This cost must be balanced against the possible benefits and the losses involved in abandoning the fish and consider drilling another hole. The driller has to promptly analyze the situation, estimate the time of fishing and take proper course from the various options available. SAFETY AT DRILL SITE General: Accidents don’t just happen. They are mostly caused by HUMAN ERRORS and MECHANICAL FAILURES. Human errors are mainly due to lack of knowledge, improper work attitude and lack of motivation. Mechanical failures are mostly due to wear and tear, overloading and bad design. Accidents are preventable if every body is concerned about safety. To achieve this staffs are to be properly trained, the activities should be supervised carefully and good housekeeping to be maintained at the site.

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(a) Proper tools and equipments should be used at the site. Proper tools make the work safer, faster and easier. Pipe wrenches and chain tongs should kept clean free from dirt and grease. When breaking rods or casings it should be ensured that even if it slips no body will be hurt.

(b) Wire ropes should be checked regularly for excessive wear and tear and should be

replaced when necessary.

(c) Hoisting plug should be completely screwed into the rods before hoisting. One should

stand clear of the rope, hoisting plug and rods while the tension in the rope is released. (d) The drill rods must be centered correctly for high speed rotation. Excessive vibration,

crooked hole, punctured hoses and loose water swivel are caused off center chucking. Basic safety rules

(a) Loose clothing should never be worn at the site. (b) Safety footwear with hard toes and heavy sole to be used. (c) Helmet is to be worn during all drilling operation (d) Safety belt to be used when working on derrick (e) Wear gloves when handling cables, rods or any sharp material and strong chemical

S.O.P-6: DRILLING FLUIDS Selection of drilling fluids depends primarily on nature of formation. The various kinds of drilling fluids used in GSI are clear water, bentonite mud, polymers, foam and cutting oil. 1.Water- It is freely available fluid primarily used in core drilling operation.It has very good

cooling properties and act as moderate lubricant and vibration dampner. 2.Water with cutting oil- Adding cutting oil to water enhances the lubricating capacity. It is used for very hard formation. 3.Water with polymer-The advantage of use of polymer are nearly the same as bentonite solution except the fact that the polymer doesn’t have the gelling properties 4. Air-Air is used as drilling fluid in DTH and some other specialized drilling operation. 5.Foam-When a foaming agent is added to the air, it will have a better borehole cleaning properties and also it gives better stability to borehole walls(specially in dry friable formation) by wetting them. The properties of drilling fluids viz viscosity, density, pH value, gel strength, sand content, filtration loss etc are to be closely monitored using field measuring tools during the operation. In other special cases e.g drilling in soluble formation and geothermal drilling require other

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specially treated fluids. Of all the drilling fluids bentonite mud is most extensively used. The drilling mud has the ability to consolidate loose or caving formation such as un-stable over burden, gravel sand, weathered shales and the like by surrounding the particles with sufficient penetration and bonding them together in a gelled mud matrix. Thus the wall front of the drilled hole acts as a casing. Properly regulated mud fluid can control the flow of water into the formation and vice- versa. This prevents swelling of clay due to hydration and avoids caving in the hole. Sodium bentonite is the clay most frequently used with fresh water to form drilling mud. In case of high salt concentration calcium based mud gives better result. Mud Properties a) The bentonite powder (3 to 4 %) by weight is to be mixed with water using Mud Mixer and

the solution is to be left for at least 24 hours for proper swelling of mud. The viscosity attained will be around 40-45 seconds. For wire line drilling viscosity of mud is to be maintained around 35-38 seconds. The density of the mud should be maintained around 1.1 kg/cm³

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b) The PH of the solution is to be maintained around 8-9. Caustic soda may be added to achieve

this PH value. For a mud pit of having capacity of 3000 lts , 1 Kg soda will bring PH in the range of 8to9

c) The mud is to be discarded if it has lost its gelling property and sand content in it has gone

beyond 5% by weight d) Return mud velocity is to be maintained around 25-30 meters per minute for efficient lifting

of cuttings from the borehole. Mud Maintenance a) Keeping the mud in good condition as recommended will increase production, improve core

recovery and prevent down hole problems b) For carrying basic test of viscosity Marsh Funnel and cup should always be kept at the drill

site. Apart from testing viscosity, the following tests should also be done regularly and their testing apparatus should be kept at the site.

Density of mud Sand content PH value of mud. c) The mud should be agitated in the pit as often as possible by using the by pass method or by

running mud agitator.

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d) If mud properties are checked and the result shows that mud is in poor condition, then

drilling should be immediately stopped and mud should be reconditioned.

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e) Use of hydrocyclone is must if bentonite mud is to be used. This removes cuttings carried by

mud and prevents recirculation of the cuttings in the hole. Thus keeping the hole clean and avoids fishing due to settling of cutting in the borehole.

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Mud Additives The effectiveness of mud depends on condition of mud, pump rate and pressure.Varius chemicals are used to treat the mud depending upon the nature of formation and the associated drilling problems. Some of most common problems and the additives required to overcome it are given below. Loss of Circulation- The drilling is to be stopped if there is complete loss of circulation. There is no control of downhole conditions while drilling blind and the string may get stuck up. Mica flakes, shredded cane fibre, barite etc are to be added in the mud (5% by weight) to control lost circulation. Discharge and pump pressure are to be reduced till it is controlled. Caving in the hole- Caving in the borehole is mainly due to swelling and falling of the shales/siltstones/ mudstones/clay etc in the borehole. This type of caving causes stuck rods and collapsing of the hole. Sodium silicate, chrome lignosulphonate etc are to be used to inhibit swelling of the clays. Hole cleaning - It is removal of cuttings/cavings from the hole. It depends on the lifting capacity of mud. To improve hole cleaning viscosity and the velocity is to be increased. CMC is be used to increase Marsh funnel viscosity. Abnormal/Artisan Pressure in hole- High pressure water flow (artisan flow) from the formation into the borehole is serious problem. This type of flow washes out the mud wall. Abnormally high pressured fluids in the rock formation can be controlled by increasing drilling mud density to give a hydrostatic head that balances the formation fluid pressure. Heavy solids like barites are used to increase mud density and full circulation is to be maintained. Stuck Rods- Most often rod gets stuck due to:

(a) Poor hole cleaning(cuttings left in the hole) (b) Swelling shales/clay(tight hole) (c) Cavings (d) Burning in the bit

To prevent jamming of rods, mud circulation system is to be continuously controlled to ensure that correct pump rate and viscosity is maintained. If the rods are stuck but there is still some circulation of mud, then first try using a spotting fluid to help lubricate and free the rod. The spotting fluid is a special additive to diesel, which will penetrate sticky cuttings and clays and lubricate the rod. The spotting fluid is spotted by pumping into position where the rods are stuck and left for 24 hours. The drill rods are then worked up and down to make it free.

S.O.P-7: CORE HANDLING & PRESERVATION The Geologist -in- Charge determines the borehole location, drilling procedures (coring/non coring), total depth, sample intervals and document the requirements in the Drilling Plan and Sampling Plan prior to the start of field activities. The Drilling Plan and Sampling Plan may be prepared for each borehole. Drilling of holes in the earth crust is the most effective means of

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prospecting for exploration of mineral deposit of all type and also for other geological activities. The basis for this prospecting is the proper recovery of core from earth crust obtained in cylindrical form by annular cutting action of bit and can be regarded as true and unaltered specimen of rock with hard mineral deposit. These cores are then tested for various chemical, mechanical and physical properties. The Geologist -in- Charge should be present at the drill site while coring is in progress. The Geologist -in- Charge will observe all handling of the core by the drill crew, will prepare a lithology log. The Geologist -in- Charge will collect core samples at specific intervals for purposes of chemical analyses and physical testing. Core recovery is defined as % of core length recovered w.r.t drilled length of run. Core recovery (%) = (Length of core/Length of run) x100 100% core recovery is difficult to attain when drilling soft rocks/fragmented formation. Standard core recovery in medium to hard formation is between 80-100% .The core recoveries in soft/ friable and loose soil/sand can be as low as 10-20% or even lower. Core recovery is classified as per the table given below- Core recovery classification-

Class Category Core recovery(%) 1. Very good 90-100 2. Good 75-90 3. Fair 50-75 4. Poor 25-50 5. Very Poor Less than 25

However, it may be emphasized that that core recovery depends on nature of strata, condition of drill accessories and type of drilling. It is largely independent of human intervention. The drilling crew takes absolute care for enhanced core recovery but it can be achieved only when better accessories and technology is used. Apart from nature of formation, there can be various reasons for low core recovery. There are broadly three main factors that affect core recovery. 1. Type of formation encountered- For loose formation there is chances ofpoor recovery. 2. Set of Equipment selected excessive washing of core in barrel-bit assembly, improper selection of bit speed and feed, excessive vibration of string, improper drilling fluid etc The diameter of core is determined by I.D of drill bit under use. The bigger core size is better for analysis. Typical core size ib diamond core drilling are 44.45 mm(BWT size) to 80.95mm(HWT size) under DCDMA series. If Swedish standards are used the core size may be 47 mm(for 66 mm T-6) to 93 mm(for 1160mm T-6)The bigger the size of the core, the higher is the cost of drilling Supplies of Core boxes Core boxes are required at the site for proper core handling. The Geologist -in- Charge should keep track of supplies of core boxes and replenish them when necessary. Core Transfer After each core run, the drill crew retrieves the core barrel or split-barrel sampling tube from the borehole. The core barrel or split-barrel sampling tube is disassembled so the core can be examined. The Geologist -in- Charge observes the core as it is being removed from the core tube or split inner barrel. The core should be extruded in continuous motion from the core barrel or split-inner barrel into a holding trough or onto a flat table, long enough to hold the entire length

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of core. The geologist-in-charge will ensure that the core is kept in the correct stratigraphic position. Core Handling The length of core recovered has to be measured prior to further transport or handling. The core is transferred from the holding trough to core boxes. Care must be taken to maintain the proper stratigraphic position of the core pieces. If the core is larger in diameter than the core box, then the core may be split along the vertical axis and placed in the core box. The uppermost piece of core is put at the top left corner of the core box, and the rest of the core box sections are filled from left to right with core, working downhole, as in reading across a page of text. Core Measurement and Labeling Core measurements are made to the nearest 0.05metre. Depths should be verified with the driller. Conventionally, all core sample loss is assumed from the end of the run. If the Geologist -in- Charge finds that the next run contains material dropped from the preceding run, it may be credited to the preceding run and the amount of recovery must be adjusted as required. The Geologist -in- Charge is will identify intervals with little or no core recovery or intervals of core removed for chemical analyses or for physical testing. If the ends of the core sample are angled, the depth is measured from approximately the middle of the angled extension. A permanent marker should be used for writing on core boxes and dividers. The label records the borehole designation and the depths of the upper and lower core ends in the box. As core boxes are filled and labeled, they are stacked in a convenient area at the drill site. The core boxes will be moved to the designated storage facility as decided by the field geologist. S.O.P-8: POST DRILLING ACTIVITY (a) Deviation Test and Logging- Advance action has to be taken by the area Geologist to conduct deviation test and the borehole logging. The Geophysical party should be available at short notice. Since the casings in the borehole tend to grip the walls of the borehole, these test should be conducted within 2-3 days.In case it is not possible to conduct the deviation test, it should be clearly recorded in the logbook and instruction for recovery of casing should be given immediately. (b) Recovery of Casings- Retrieval of the casings from the borehole should be done immediately by means of established procedures. While conducting fishing operation for recovery of casings, the following points should be observed carefully. Extra time in retrieving the casing should be allowed only when the casings recovered are fit for reuse and is economical also. In any case fishing for the recovery of casings should not be continued for more than 5 (five) days. (c) Restoration of Drill Site – The drill site after removal of machineries and tubular should be restored to its original form by debris-iron scrap, oil, mud etc. Few saplings should also be planted at the site. Survey reports for the borehole loss should be prepared adopting the usual formalities within 10 days of completion of the borehole. (d) Soil Sampling through Core Drilling & S.P.T- The detailed work of ‘Soil Sampling through Core Drilling and SPT’ involves drive sampling technique (Dry sampling) for obtaining

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the representative samples of soil through S.P.T (Standard Penetration Test) for determining the relative density and cohesiveness of the soil. Core drilling with fluid circulation is done for 30-50 mts to know the condition of soil and the bedrock. The peculiar characteristic of top rock being frequently broken and leached by the action of ground water renders it difficult to differentiate between the overlaying soil (fine/coarse grained soil with organic content and gravel/boulders) and the unconsolidated rock. As such the job of recovering representative soil samples through in situ geo-technical testing technique such as Standard Penetration Test is an arduous task. It is equally difficult to get good rock core in unconsolidated formations of shallow bore hole. Presence of ground water in the bore hole makes it more difficult to get in situ dry samples of soil/unconsolidated formation. It necessitates simultaneous extension of casings along with the core drilling to maintain the borehole condition for conducting S.P.T at required intervals and to prevent contamination of bottom samples due to collapsing side walls. The activity analyses of the field drilling operation for SPT/Core drilling can are:- 1. Core drilling upto 0.95-1.00 mts from surface. 2. Dry drilling for 10 cm to remove contamination from the hole due to water/ left over debris 3. Lowering of casing upto bottom 4. Lowering of SPT assembly( Standard split tube sampler with AW drill rod & hammer) and recording of data about resistance of the soil to penetration(Resistance, N- Number of blows per 30 cm of penetration through drive sampling techniques using 65 kg hammer released from a height of 75 cm) 5. Continue Core drilling/SPT for 30-50 mts or as required. 6. Enlarge the hole by reaming and extension of casing up to bottom after every SPT procedure. It is quite evident from above that due to formational variations and unpredictability of zones encountered, the activity of SPT cum Core drilling takes much more time in completion of hole successfully to achieve the desired objective as compared to conventional core drilling. S.P.T Procedure (IS: 2131-1981) Procedure for SPT 1. The split spoon sampler resting on the bottom of the bore hole should be allowed to sink under

its own weight, and then it should be driven 15 cm below with the blows of hammer dropping from 75 cm height. Thereafter it should be further driven by 30-50 cm below (except when the sampler is full of core).The number of blows required for every 15 cm of penetration is recorded. The first 15 cm of drive may be considered as seating drive. The total blows required for 2nd and 3rd 15 cm of penetration may be termed as penetration resistance ‘N’. If the split spoon sampler is driven less than 45 cm then the penetration resistance shall be for the last 30 cm of penetration or if less than 30 cm is penetrated the log should record the number of blows and the depth.

2. The entire sampler sometimes may sink under its own weight when soft soil strata are

encountered. Under such conditions, it may not be necessary to give any blow to the split spoon sampler and the SPT values should be recorded as zero.

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Cleaning of the borehole 1. In case where wash boring is adopted for cleaning the borehole, only side discharged bit are to

be used. The process of jotting through a open tube sampler and ten testing and sampling when the desired depth is reached is not permissible.

2. While boring through soils such as sands that may be disturbed by the flow of water into the

drill hole, water should not be added while boring above water table. While boring below the water table, the water in the hole shall be maintained at least 1.5 m above water table. The raised level of water in the bore hole should be maintained even if casing is used to stabilize the borehole.

While boring through sand using casing to stabilize the sides of the borehole the outer diameter of the shell shall be at least 25 mm smaller than the inner diameter of the casing. The distance between the end of casing and the bottom of the hole should be as close as possible and in any case should not exceed 150 mm if only water is used to stabilize the hole. For bentonite mud the distance may be up to 300 mm.

3. The borehole shall be cleaned up to testing or sampling elevation using suitable tools, such as

augurs that will ensure minimum mixing of the soil. In cohesive soils the borehole may be cleaned by bailer with a flap valve. It should not be used in sands.

The drilling progress for the SPT work mainly depends upon- (a) Frequency of SPT- As per IS standard tests shall be made at every change in stratum or at

intervals of not more than 1.5 mts, whichever is less. Tests may be done at lesser intervals if specified or considered necessary. The intervals to be increased to 3 mts if in between vane shear test is to be4 performed or as may deem necessary.

(b) Frequent borehole shifting-To minimize down time in frequent bore hole , the drill machine

along with pump unit should be truck mounted. The down time should not be more than 3-4 days.

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Drilling Requisition Proposal Annexure-IA

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Annexure-II Diamond Bit/Reamer Shell record: Bit/Reamer Shell No- Unit No- Type of bit - Area- Date of issue- Bore Hole No From To Meters Total Formation Drilled-

Very Hard Hard Medium Soft Good coring Solid Broken Abrasive

Comments:

Unit-in- Charge

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Annexure-IIIA

LIST OF ACCESSORIES TO BE PROCURED UNDER KIT ALLOWANCE ( For Gr ‘A’ & ‘B’ officer for a period of 5 years) Sl No Item Quantity Rate(Approx) Amount 1. Camp Cot 2 Nos Rs. 5000/-each Rs. 10000/- 2. Folding Chair(steel) 4 Nos Rs. 500/-each Rs. 2000/- 3. Trunk(steel) 1 Nos Rs. 1000/-each Rs. 1000/- 4. Kitchen box(wooden) 1 Nos Rs. 1000/-each Rs. 1000/- 5. Lighting(solar powered) 1 Set Rs. 4000/-each Rs. 4000/- 6. Storage water filter 1 Nos Rs. 4000/-each Rs. 4000/- 7. Water drum(sintex) 1 Nos Rs. 2000/-each Rs. 2000/- 8. Gum boot/Hunter shoes 2 Pair Rs. 500/-each Rs. 1000/- 9. Umbrella 1 Nos Rs. 300/-each Rs. 300/- 10. Steel Table 2 Nos Rs. 1000/-each Rs. 2000/- 11. Pressure Cooker 1Nos Rs. 1500/-each Rs. 1500/- 12. Gas Cylinder connection 1 Nos Rs. 3000/-each Rs. 3000/- 13. Tea Set/ Thermos Flask 1 Set Rs. 500/-each Rs. 1000/- 14. Water bottle,jug,glass etc 1 Set Rs. 500/-each Rs. 500/- 15. Mosquito net 2 Nos Rs. 1000/-each Rs. 2000/- Total- Rs.34500/- Kit allowance worth Rs 35000/- should be provided to all the Gr ‘A’ & ‘B’ officers who are posted in the field once in five years. ( For Gr ‘C’ & ‘D’ official for a period of 5 years) Sl No Item Quantity Rate(Approx) Amount 1. Camp Cot 1 Nos Rs. 2500/-each Rs. 2500/- 2. Folding Chair(steel) 2 Nos Rs. 250/-each Rs. 500/- 3. Trunk(steel) 1 Nos Rs. 500/-each Rs. 500/- 4. Kitchen box(wooden) 1 Nos Rs. 500/-each Rs. 500/- 5. Lighting(solar powered) 1 Set Rs. 1000/-each Rs. 1000/- 6. Storage water filter 1 Nos Rs. 1000/-each Rs. 1000/- 7. Water drum(sintex) 1 Nos Rs. 1000/-each Rs. 1000/- 8. Gum boot/Hunter shoes 2 Pair Rs. 500/-each Rs. 1000/- 9. Umbrella 1 Nos Rs. 250/-each Rs. 250/- 10. Steel Table 1 Nos Rs. 500/-each Rs. 500/- 11. Pressure Cooker 1Nos Rs. 1000/-each Rs. 1000/- 12. Stove 1 Nos Rs. 1000/-each Rs. 1000/- 13. Tea Set/ Thermos Flask 1 Set Rs. 500/-each Rs. 500/- 14. Water bottle,jug,glass etc 1 Set Rs. 250/-each Rs. 250/- 15. Mosquito net 2 Nos Rs. 500/-each Rs. 500/- Total- Rs.12000/- Kit allowance worth Rs 12000/- should be provided to all the Gr ‘C’ & ‘D’ officials who are posted in the field once in five years.

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Annexure- III B The major drilling accessories that are required to be kept at the site for successful completion of a 650 mts borehole for coal investigation is given below. Sl No Description of stores Quantity 1. Drill rig of 1000 mts capacity 1 No 2. Mud Pump of 900 mts capacity 2 Nos 3. Slush Pump 1 No 4. 4 leg steel derrick 1 Set complete with braces 5. NW Right Hand Drill Rod(3 mts) 100 Nos 6. BW Right Hand Drill Rod(3 mts) 250 Nos 7. HQ Drill Rod 100 Nos 8. NQ Drill Rod 250 Nos 9. 146 mm Casing(3 mts length) 20 Nos 10. 127 mm Casing(3 mts length) 75 Nos 11. 108 mm Casing(3 mts length) 100 Nos 12. 116,101,86 and 76 mm T-6 D/T barrel 2 Nos each 13. HQ & NQ Core barrel with accessories 2 Nos each 14. 190/164 mm RR bit 2 Nos each 15. 146/131/127 mm Casing TC bit 5 Nos each 16. 116/101/86/76 mm diamond bit 6 Nos each 17. HQ/NQ diamond bit 4 Nos each 18. 18,24,36 and 48” pipe wrenches 2 Nos each 19. Bentonite mud 3 MT 20. Male female recovery tap 2 set of each size 21. Left hand drill rod 750 mts 22. Suction hose/Pressure hose 1 No each 23. Steel wire rope 2 Rolls 24. Hydro Cyclone 2 Set

Other major requirements are GI pipes, sheaves, hoisting plugs, water swivel of BW/NW size, casing heads, clamps, pramalee wrenches, fishing tools, deflection tools, drive hammer assembly of 300 lbs, safety clamps, soil samplers, consumable spare parts of rig/pump, personal safety kit, tool box and all the measuring tools.

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Annex-IV

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Annex-IV

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Annexure-V Peer Review Report

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Annexure-V