Upstream Processing

8/8/2019 Upstream Processing

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GEOLOGICAL EXPLORATION OF OIL (PETROLEUM) AND

UPSTREAM PROCESSING

Introduction:

The exploration of hydrocarbons/oil comes under the branch of science calledexploration geophysics. It is the search by petroleum geologists for oil and gas beneath thesurface of earth. This involves seismology and many operations of mining engineering. Thewhole process is a long one which needs a large crew and involves a lot of risks. Basicallythe process starts with superficial observations for seepage and similar signs and ends up inchemical process plants where the hydrocarbons are separated and conditioned for meetingthe required standards.

The petroleum industry is usually divided into three major components: Upstream,midstream and downstream , though midstream operations are usually included in thedownstream category.

The upstream oil refers to the searching for and the recovery and production of crudeoil and natural gas. This includes the searching for potential underground or underwater oiland gas fields, drilling of exploratory wells, and subsequently operating the wells that recover and bring the crude oil and/or raw natural gas to the surface. The upstream oil sector is alsoknown as the exploration and production (E&P) sector .

The downstream oil sector refers to the refining of crude oil, and the selling anddistribution of natural gas and products derived from crude oil. Such products includeliquefied petroleum gas (LPG), gasoline or petrol, jet fuel, diesel oil, other fuel oils, asphaltand petroleum coke. This includes oil refineries, petrochemical plants, petroleum productdistribution, retail outlets and natural gas distribution companies.

This report presents an overview of the upstream oil exploration processes i.e.exploration and production of petroleum.


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EXPLORATION OF PETROLEUM:

As al ady s tat d, t expl ati of pe t oleum is t e search by pe troleumgeologists and geophys icists for hydrocarbon depos its benea th the Ear th's surface. Onshoreexploration is eas ier than offshore exp loration. Genera lly, v isi ble surface fea tures such as oil

t l ockmarks (underwa ter cra ters caused by escap ing gas) prov ide bas ic evidence of hydrocarbon genera tion. Seepage is an indicator of accumu lations,migration pa thways or ma ture source k itchens.

SEEPAGE :

A good def inition of a seep is '' t

surface express ion of a m i ra tion pa t

way, a l ong w

ich pe t ro l eum i s curren tl y f l owing, dr iven by buoyancy from a sub-surface or i g in'' (Clarke &Clever ly, 1990).

(Los Barroso, 1922),

raq (K irkuk, 1927), Eas t Texas (1930), Bahra in (1932) and Kuwa it .

Seepage informa tion is a key p iece of ev idencefor reduc ing the r isk on source presence in anew bas in as seeps or iginate by leakage from

bur ied oil and gas accumu lations .A t the mos t bas ic level, this demons trates that the bas incontains a genera ting source rock and hence aviable petroleum sys tem. Surface seepage was

assoc iated w ith Suma tra (1885), Texas(Spindletop, 1901), Ok lahoma (1905), Pers ia(Ma jid- -Sulaiman, 1908), Venezue la

n the offshore, seep ing o il and gas are of ten eas ier todetect due to the fac t that oil is norma lly transpor ted from thesea-bed ven t to the surface as o il- coa ted gas bubb les.

At the surface, the gas bubb le burs ts and the o il rema ins onthe surface as a thin oil f ilm. n ca lm sea cond itions, these canof ten be v iewed as beau tiful, ir idescen t concen tr ic shapes,typically 0.5 to 1 me tre in diameter, known as 'o il pancakes'.As seepage con tinues over time, these coa lesce to form larger slicks that are de tectable from a ircraf t.


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C ommonly observed leakage induced features include:

1 . Biological build-ups at or near the sea floor

2. Mechanical disturbances in the shallow sediments, including pockmarks and mudvolcanoes.

3. Diagenetic alterations in the shallow sediments most commonly carbonate precipitation.

4. Rock property variations due to the presence of hydrocarbons, including bright spots andflat spots.

5. Hydrocarbon-related diagenetic zones (HRDZs).

6. Gas chimneys .

A number of techniques have been developed for mapping offshore seepage. Some of themwhich are generally used are :

(a) SAR (synthetic aperture radar) : Synthetic aperture radar (SAR) is a form of radar inwhich multiple radar images are processed to yield higher resolution images thanwould be possible by conventional means. It has the ability to image surface oil seepsremotely with wide swath coverage (typically 100 x 100 km scenes for ERS and 1 65 x1 65kms for Radarsat Wide 1 ) and at low cost. Moreover, satellite data in free skies is

being continuously acquired, thus providing multi-temporal satellite data over anyarea of the globe. Such repeat seeps provide the location for follow-up surfacesampling from which key geochemical information on the reservoir oil can be

obtained ahead of the drill. SAR satellites scan the oceans continuously on fixed polar orbits. They have advantages over optical satellite systems, such as Landsat T M andairborne systems in that they observe night and day and penetrate cloud cover. SAR creates images of the sea surface detailing its morphology. Radar images map slicks(flat patches of the surface) that can be related by analysis to petroleum seepage.

(b) A L (airborne laser fluorosensor): an aircraft mounted ultra-violet laser is pulsedat 50 Hz onto the sea surface and any fluorescence caused by a thin oil film is detected\and recorded.

(c) H yper spectral scanner : An aircraft mounted detector records an image of the seasurface for a selected range of light wavelengths, which are selected to highlight any

oil slicks. The AHS (Airborne Hyper spectral Scanner) instrument has near about 8 0 spectral bands covering the visible and near infrared (VN IR), short wave infrared(SWIR), mid infrared ( MIR) and thermal infrared (T IR) spectral range .

Most seepage mapping techniques provide only a snapshot of present day seepage. The SAR technique requires multiple-coverage at different times to increase the chance of observing aseep, which may only occur episodically. Analysis of seismic data can however reveal past


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seepage phases. Seeped o il samp les can be ob tained by seabed cor ing or, in some cases,samp ling a surface s lick.

SEI SMIC SURVEY S :

Most of the wor lds sedimentary bas ins do no t have suff iciently good source rocksto genera te enough hydrocarbons to form commerc ial accumu lations. When exp lor ing in anunproven reg ion, it is mos t impor tant to reduce the r isk of insuff icient source. f there is nosource, there can be no accumu lation. To tack le these s ituations and to reduce r isk,Ref lect i se ism ic imag i g of the subsurface is the ma in survey ing tool used by exp lorationcompan ies. Af ter the acqu ired da ta is processed, images of the subsurface geo logy are

produced. These images are interpre ted to produce maps of the subsurface layers, wh ich areused to identify po tential hydrocarbon traps.

Seismo logy is the sc ientif ic study of ear thquakes and the propaga tion of e lastic wavesthrough the Ear th. The f ield also includes s tudies of ear thquake effec ts, such as tsunam is aswell as d iverse se ismic sources such as vo lcan ic, tectonic, ocean ic, atmospher ic, and ar tif icial

processes (such as exp losions).

Two types of ref lection se ismic surveys are used for hydrocarbon exp loration. 2D se ismic imaging:-Separa te seismic lines spaced from severa l hundred me tres to

severa l k ilometres are used to prov ide an indication of the subsurface s truc ture a t relatively low cos t. These are ca lled 2D se ismic lines.

3D se ismic imaging:-When the lines are spaced a t 50m or less, con tinuous coverage,or 3D se ismic data is ob tained. Th is data is processed to produce a un iformly samp led

Seismic waves are waves of force that travel

through the Earth or other elastic body, for

example as the result of an earthquake,explosion, or some other process that imparts

forces to the body. Seismic waves are also

continually excited on Earth by the incessant pounding of ocean waves and the wind. Seismic

waves are studied by seismologists, and measured by a seismograph, which records the

output of a seismometer, or geophone. For

seismic studies of offshore oil reservoirs ,

hydrophones may give additional information.

The propagation velocity of the waves depends

on density and elasticity of the medium which is

penetrated.


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3D vo lume of da ta, wh ich produces a much more accura te image of the subsurfacegeology.

Some compan ies incorpora te da ta from o ther survey types to ref ine their geo logical mode l.These surveys can include grav ity, magne tic and var ious seepage de tectionsurveys.

Out li e of Seism ic survey techn iq ue

BASIC PRINCI PLE: Any med ium that can suppor t seismic wave propaga tion may bedescr i bed as hav ing an impedance, wh ich depends on ve locity of the wave and dens ity of themater ial medium.When a se ismic wave encoun ters a boundary be tween two d ifferen t mater ials withdifferen t impedances, some of the energy of the wave w ill be ref lected off the boundary, wh ile some of it will be transm itted through the boundary.

Amp litude is an impor tant proper ty of waves. Af ter

ref lection or refrac tion the wave undergoes a change in amp litudeand this change g ives an idea abou t sub-ear th struc tures. Theamplitude of the ref lected wave is pred icted by mu lti plying theamplitude of the incom ing wave by the se i smic ref l ectioncoeff icient R, determined by the impedance con tras t between thetwo ma ter ials. Similar ly, the amp litude of the incom ing wave ismulti plied by the t ransm i ss ion coeff icient to pred ict the amp litudeof the wave transm itted through the boundary. By observ ingchanges in the streng th of ref lectors, se ismo logists can infer changes in the se ismic impedances. n turn, they use thisinforma tion to infer changes in the proper ties of the rocks a t theinterface, such as dens ity and e lastic modu lus. For non-norma l incidence (at an ang le), a phenomenon known as mode convers ionoccurs. Long itudinal waves (P-waves) are conver ted to transverse waves (S-waves) and v iceversa. The transm itted energy w ill be ben t, or refrac ted, accord ing to Sne ll's law. Theexpress ions for the ref lection and transm ission coeff icients are found by app lying appropr iate

boundary cond itions to the wave equa tion.The time it takes for a ref lection from a par ticular boundary to arr ive a t the geophone

is ca lled the t ra vel time. f the se ismic wave ve locity in the rock is known, then the travel time may be used to estimate the dep th to the ref lector. For a s imple ver tically travellingwave, the travel time t from the surface to the ref lector and back is ca lled the Two-Way T ime(TWT) and is given by the formu la

,where d is the dep th of the ref lector and V is the wave ve locity in the rock.A ser ies of apparen tly re lated ref lections on severa l seismograms is of ten referred to as aref l ection e vent . By corre lating ref lection even ts, a se ismo logist can crea te an es timatedcross-sec tion of the geo logic struc ture that genera ted the ref lections. n terpre tation of largesurveys is usua lly performed w ith programs us ing h igh-end three d imens iona l compu ter graph ics.

A geophone


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First of all, a se ismic source is initiated wh ich produces the waves. These waves travel

into the ear th and are ref lected back from the interfaces be tween d ifferen t sub- layers.These ref lected energy waves are recorded over a prede termined time per iod (ca lled therecord length). R ecord ing the ref lected waves is done us ing one or more se ismome ters. Onland, the typical seismome ter used in a ref lection exper iment is a sma ll, por tab le instrumen t

known as a geophone, wh ich conver ts ground mo tion into an ana log electr ical signa l. nwater, hydrophones, wh ich conver t pressure changes into electr ical signa ls, are used. As theseismome ters de tect the arr ival of the se ismic waves, the s igna ls are conver ted to digital formand recorded. The s igna ls may then be d isplayed by a compu ter as se ismograms for interpre tation by a se ismologist. Typ ically, the recorded s igna ls are sub jected to signif icant amoun ts of s igna l process ing and var ious imaging processes before they are ready to beinterpre ted.

.

Exploration on land

The exploration on land cons ists of ma inly 2 k inds of crew1. seismic land crew2. camp personne l

The se ism ic Land Crew :This cons ists ma inly of the sur veyors , l ayou t and l oad ing cre w,

shoo t ers and recorders and t he pick up cre w .The con tractor f irst determines the long itude and latitudecoord inates of the source and receiver lines us ing mob ile GPSstations. Source lines are lines wh ich con tain sho t point s .These

are the po ints on wh ich sho ts are f ired to initiate seismic waves.Rece iver lines are the lines on wh ich there are rece iver po int s - points where the ref lected waves are rece ived and recorded.The surveyors need to survey in sho t and rece iver po ints onsource and rece iver lines. When a sho t or rece iver po int isreached, this pos ition w ill be s taked ou t or marked w ith the sho t or rece iver s tation number and line number.

Once suff icient lines of sho t and rece iver po ints have been surveyed in and sho t holes have been dr illed to theappropr iate dep th, loaders put explosive charges into the sho t holes on the source lines (accord ing to the pro ject spec if ication)and the rece iver s tations w ill be laid out with geophone spreads

on the rece iver lines. When correspond ing sho t and rece iver lines are ready, the shooters prepare a s ingle sho t hole ready for f ir ing, wh ilst the record ingshack w ill be hooked up to the geophone spread laid on the correspond ing rece iver line torecord the ref lected da ta. Once a charge is ready to be sho t, the record ing shack initiates theshot hole f ir ing sequence v ia a rad io link and records the se ismic da ta from the who legeophone spread on to magne tic med ium. Once a sho t is comp leted, the shoo ters move to thenext shot hole and the shoo t / record sequence beg ins aga in.


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These days v i bra tor crews or vibroseis havereplaced loaders & shoo ters. V i brations are crea ted bythe compu ter-coord inated vi bra tion of hydrau licallycontrolled p lates on v i bra tor trucks and the vi bra tor trucks move from sho t hole to sho t hole on thedesignated source line .

Land surveys requ ire crews to dep loy thehundreds or thousands of geophones necessary torecord the da ta. Mos t surveys today are conduc ted by

laying ou t a two-d imens iona l array of geophones together w ith a two-d imens iona l pattern of source po ints. Th is allows the interpreter to crea te a three-d imens iona l image of the geo logy

benea th the array, so these are ca lled 3D surveys. Less expens ive survey me thods use one-dimens iona l lines of geophones that only allowed the interpre ter to make two-d imens iona l cross-sec tions. Th is is all abou t technical crew.

Ass ist ing Crew : the suppor ting crew arranges for the ca ter ing, was te managemen t anddisposa l, camp accommoda tions, wash ing fac ilities, wa ter supp ly, laundry in the ma in camp .And then there are f ly-camps wh ich are temporary camps se t up away from the ma in campon large land se ismic opera tions, for examp le where the distance is too far to dr ive back tothe ma in camp w ith vi bra tor trucks. A ll of the crews veh icles (ma intenance, fue l, spares e tc),secur ity, poss i ble he licop ter opera tions, res tock ing of the exp losive magaz ine, med ical suppor t and many o ther logistical and suppor t func tions.

Marine Exploration

U SE OF ST R EAME R S : Deep wa ter mar ine surveys are conduc ted us ing vesse lscapab le of towing one or more se ismic cab les known as s treamers. Modern 3D surveys use

multi ple streamers dep loyed in para llel, to record da tasuitable for the three-d imens iona l interpre tation of thestructures benea th the sea bed. A s ingle vesse l may towanything up to 10+ s treamers, each 6 km+ in length,spaced 50150 m apar t. Hydrophones are dep loyed a t regu lar interva ls within each s treamer. Thesehydrophones are used to record sound s igna ls which areref lected back from s truc tures w ithin the rock. Toaccura tely ca lculate where subsurface fea tures arelocated, nav igator compu te the pos ition of bo th thesound source and each hydrophone group wh ichrecords the s igna l. The pos itioning accuracy requ ired isachieved us ing a comb ination of acous tic ne tworks,compasses and GPS rece ivers (of ten used w ith a rad iocorrec tion app lied ca ll a differen tial GPS or DGPS).

R eceiver line spread of geophones on N.

Afr ica deser t crew


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OCEAN BOTTOM CA BLES : Mar ine surveys canalso be conduc ted us ing sensors a ttached to an OceanBottom Cab le (OBC) laid ou t on the ocean bo ttom ra ther than in towed s treamers. Due to opera tiona l limitations,most of these types of surveys are conduc ted in wa ter

depths less than 70 me ters, however O BC crews in recen t years have acqu ired 3D surveys in dep ths up to 2000meters. One opera tiona l advan tage is that obstacles (such as

platforms) do no t limit the acqu isition as much as they dofor s treamer surveys. Mos t of the OBC surveys use dua l componen t receivers, comb ining a pressure sensor (hydrophone) and a ver tical par ticle ve locity sensor (ver tical geophone). O BC surveys can a lso use four componen ts, i.e. hydrophone componen ts plus the three or thogona l velocity sensors. Four componen t OBC surveys have the advan tage of be ing ab le to a lso record shear waves , wh ich

do no t travel through wa ter. Mu lti ple componen t OBC surveys hence can lead to improvedsubsurface imaging. Ocean Bottom Cab le surveys can a lso cos t signif ican tly more thanconven tiona l streamer surveys over the same area. Th is add itiona l cost is usua lly on ly

justif ied when the improved imaging is requ ired for accura te reservo ir delinea tion, or whensurface obs tacles preven t a conven tiona l streamer survey from be ing acqu ired in the area.

Dr illi ng for o il

Once the co llected da ta is suff icient to sugges t the presence of hydrocarbons benea ththe place, the dr illing works beg in. t is necessary to dr ill a ho le to obtain crude o il andnatura l gas from under the ear th's surface. The ho le is made us ing aro tary dr illing r ig.

The Rotary Dr illi ng R ig :

A d rilling rig is a mach ine wh ich crea tes ho les(usua lly ca lled boreho les) and /or shaf ts in the ground.Dr illing r igs can be mass ive structures hous ing equ i pmen t used to dr ill water we lls, oil wells, or na tura l gasextraction we lls. They samp le sub-surface m inera l depos its, test rock, so il and groundwa ter phys ical

proper ties and are a lso used to install sub-surfacefabr ications, such as underground u tiliti es,instrumen tation, tunne ls or we lls etc.Dr illing r igs can be mob ile equ i pmen t moun ted on trucks,tracks or trailers, or more permanen t land or mar ine-

based s tructures (such as o il platforms, common ly ca lled'offshore o il r igs' even if they don' t contain a dr illing r ig).The term "r ig" therefore genera lly refers to the comp lexof equ i pmen t that is used to pene trate the surface of the


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ear th's crus t.

Work ing: The ro tary dr illing r ig uses a d rill bit to cut through the ear th and crea te a ho le. As the ho legets deeper, p i pe is added to the dr ill bit to allow it to dig fur ther. These lengths of dr ill pi peform the d rill string . Th is p i pe is connec ted to an eng ine that turns the dr ill bit to cut the ho le.The ro tary r ig opera tes the same as a hand-he ld electr ic dr ill. The e lectr ic dr ill has a mo tor that turns the dr ill bit and suff icient weight must be app lied to keep the dr ill in con tact withthe bo ttom of the ho le.

Operat ions:

There are four ma in opera tions in a dr illing r ig: hoi sting, ro t ating, c ircu l ating, and po wer .

(A)Ho ist ing:

The ho isting sys tem is bas ically used to ra ise and lower p i pe in and ou t of the ho leand to suppor t the dr ill str ing to con trol the we ight on the dr ill bit dur ing dr illing.

The ho isting sys tem aga in cons ists of ma inly 4 par ts. These are derr ick, trave ling andcrown b locks, the dr illing line, the drawworks.

(1)Derr ick : An o il derr ick is des igned for use in oil and na tura l gas produc tion. t suppor ts the dr ill bit,

pi pe (dr ill str ing), trave lling and crown b locks.The bas ic oil derr ick has an upr ight stationary sec tion wh ich is po tentially capab le of

suppor ting hundreds of tons of we ight, comb ined w ith a movab le boom wh ich is used to ra iseand lower equ i pmen t. Derr icks of var ious des igns have been in use for cen tur ies to extract valuab le resources from under the Ear th, and con tinue to bewidely used today.

Ear ly derr icks cons isted of a framework wh ich wasdesigned to ho ld a large po le used for percuss ive dr illing,which is accomp lished by repea tedly bea ting the ear th tomake a ho le. A modern o il derr ick typically uses a dr ill bit which is capab le of b iting through the subs trate, and coo ledwith cons tant slurry of mud to preven t it from ge tting toohot. Typ ically, as the dr ill bit sinks in, the ho le is lined to

preven t a cave in. Once the dr ill reaches the oil, it iswithdrawn so that pumps and p i pes can be inser ted into thehole to extract it.

n an area r ich in oil, an o il derr ick is des igned to be a permanen t struc ture, and w ill continue to opera te for many


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years. Por table oil derr icks are a lso used in less resource r ich areas, or to make pre liminaryexplorations in areas of po tential interest. n genera l, a por table oil derr ick is no t capab le of hand ling as much we ight as a permanen t one, wh ich can be anchored to the ground and bu ilt with heavy we ight equi pmen t since it does no t have to be moved. (2 )Trave lling and crown b locks :

The crown and traveling b locks are a se t of pu lleys that raise and lower the dr ill str ing. Thecrown b lock is a s tationary pu lley located a t the top of the derr ick. The traveling b lock movesup and down and is used to ra ise and lower the dr ill str ing. These pu lleys are connec ted to thedr ill str ing with a large d iame ter steel cable. The fo llowing f igures show the b locks.

Crown- Block

Trave lling-b lock


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(3 )The dr illing line :

I n a dr illing r ig, the dr ill line is a mu lti-thread, twisted wire rope that is threaded or reevedthrough the travelling b lock and crown b lock to fac ilitate the lower ing and lif ting of the dr ill str ing into and ou t of the we ll bore. On larger d iame ter lines, tension s trengths over a m illion

pounds are poss i ble.

(4 )Draw-works

The draw works con tains a large drum around wh ich thedr illing cab le is wrapped. I t cons ists of a large-d iameter steel spoo l, brakes, a power source and assor ted aux iliary dev ices.The pr imary func tion of the draw works is to ree l out and ree l in the dr illing line, a large d iame ter wire rope, in a con trolledfashion. The dr illing line is ree led over the crown b lock andtrave lling block to ga in mechan ical advan tage in a "b lock andtack le" or "pu lley" fash ion. Th is ree ling ou t and in of thedr illing line causes the travelling b lock, and wha tever may behang ing undernea th it, to be lowered into or ra ised ou t of thewell bore. The ree ling ou t of the dr illing line is powered bygrav ity and ree ling in by an e lectr ic motor or d iese l engine.

W ork ing:Hoisting is done by w ith the he l p of above men tioned componen ts. The dr illing line passesthrough the trave lling and crown b locks and is wound around the draw-works. The crown

block, wh ich ac ts as the ma in pu lley, is presen t at the top of the derr ick and draws the dr illingline as per requ iremen t. The travelling b lock, wh ich connec ts this setup fur ther to the dr illingstr ing, is attached to the dr illing line and moves ver tically with it. The Derr ick ac ts as a

backbone and suppor ts the who le setup.

(B )ROTATING:

R otation is performed w ith rotating equ i pmen t. Basically, it turns the dr ill bit. This equ i pmen t cons ists of the swivel , t he ke ll y, t he ro t ary t ab l e, t he dr ill pi pe, t he dr ill coll ars, and t hedr illing b it The term Dr illi ng Str ing is loosely app lied to the assemb led co llection of thedr ill pi pe, dr ill collars, tools and dr ill bit.

(1)Swivel:The sw ivel is attached to the bo ttom of the travelling b lock and perm its the dr ill str ing to rotate. The p icture on the r ight shows a sw ivel.


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(2)Ke lly and Rotary Tab le:The ke lly is a square or hexagona l shaped sec tionof p i pe that is attached to the sw ivel. The ke lly f itsin a ma tching s lot in the ro tary table. As the ro tarytable turns the ke lly is also turned. I t rotates us ing

power from e lectr ic motors. The movemen t of thekelly rotates the dr ill str ing and the dr ill bit.

(3 )Dr ill str ing:

A dr ill str ing is a co lumn or s tr ing of dr ill pi pes that transm its dr illing f luid (via the mud

pumps) and ro tationa l power (v ia the ke lly dr ive or top dr ive) to the dr ill bit. The term isloosely app lied as the assemb led co llection of the dr ill pi pe, dr ill coll ars, t ool s and dr ill bit The dr ill str ing is hollow so that Dr illing f luid can be pumped down through it and c ircu lated

back up the annu lus (vo id be tween the dr ill str ing and the forma tion).

Dr ill str ing components

The dr ill str ing is typically made up of 4 sec tions : Bott om ho l eassemb l y ( BHA) , Trans ition p i pe (Of t en H ea v y We i gh t Dr ill

P i pe ) ,Dr ill P i pe, Dr ill S t em subs.

Each sec tion is made up of severa l componen ts and joinedtogether us ing spec ial threaded connec tions known as tool joints.

(a) Bottom ho le assemb ly (B HA)

The BHA is made up of a dr ill bit which is used to break-up therock forma tions, dr ill coll ars which are heavy, thick-wa lledtubu lar used to app ly weight to the dr ill bit, and st ab ilizers whichkeep the dr illing assemb ly cen tred in the ho le. The BHA may a lsocontain other componen ts such as a down-ho le mo tor, R otarySteerab le Sys tem, measuremen t while dr illing (MWD),

and logg ing wh ile dr illing (LWD) tools.

y square type Ke lly

y hexagona l type ke lly


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(b)Dr ill p ipe

Dr ill pi pe makes up the ma jor ity of a dr ill str ing. They are round s teel tubes abou t 30 fee t long w ith a d iameter of from 4 to 5 inches. A dr ill str ing is typically abou t 15,000 fee t inlength for an o il or gas we ll ver tically dr illed onshore in the U nited States andmay ex tend toover 30,000 fee t for an offshore dev iated we ll. Dr ill pi pe has threaded connec tions on eachend that allow the p i pe to be joined together to form longer sec tions as the ho le gets deeper.

(c)Trans it ion p ipe

Heavywe ight dr ill pi pe (HWDP) is used to make the trans ition be tween the dr ill collars anddr ill pi pe. The func tion of the HWDP is to prov ide a f lexi ble trans ition be tween the dr ill collars and the dr ill pi pe. Th is hel ps to reduce the number of fa tigue fa ilures seen d irectlyabove the BHA. A secondary use of HWDP is to add add itiona l weight to the dr ill bit.

(d)Dr ill Stem Subs

Dr ill stem subs are used to connec t dr ill str ing e lements.(e)Dr ill B it :

The dr illing b it is used to crea te the ho le. Dr illing b it sizes range from s ixinches to three fee t in diame ter. The mos t common dr ill bits are ro ller conebits and diamond b its. R oller cone b its have three cones con taining rowsof teeth. The cones ro tate on bear ings and turn as the dr illing b it rotates.

The teeth cu t and crush the rock to crea te the ho le. The b it also con tainssma ll nozz les that spray dr illing f lu ids to remove the rock fragmen ts fromthe bo ttom of the ho le.

Diamond b its have a s ingle f ixed head that contains many sma ll diamonds. As the b it turnsthe diamonds cu t the rock. D iamond b its also have nozz les to wash away the broken p ieces of rock. D ifferen t dr illing b its are used depend ing on the type of rock that is encoun tered.

WOR K I NG:

The ro tary table rotates by draw ing power from e lectr ic motors. The Ke lly wh ich f its into aslot on the ro tary table also ro tates with it. The ro tation of Ke lly aga in rotates the dr illingstr ing the b it. Due to the presence of teeth, the dr illing b it cuts through the ear th surface.

A drill bit


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(C)CIRCULATION:

The dr illing opera tion uses f luid to reduce fr iction and remove rock fragmen ts or cu ttings.This also ac ts as a coo lant which dra ins the mass ive amoun t of hea t produced dur ing dr illing.

The c ircu lating sys tem pumps these dr illing f luids down the ho le, ou t of the nozz le in thedr illing b it, and re turns them to the surface where the debr is separa te from the f luid. Dr illing f luid is also known as dr illing mud because of its charac ter istic brown co lor. Thedr illing mud is mixed in tanks. The mud is pumped through a hose to the sw ivel, down thekelly and into the dr ill pi pe. The mud goes down the dr ill str ing and ge ts out of the dr ill str ingthrough the ho les on the dr ill bit.The cu ttings are separa ted from the mud in a v i brating screen ca lled a sha le shaker. Thecuttings are trapped on the screen and the mud passes through the screen on to the mud pit.The c ircu lating pump p icks up this clean mud and sends back down the ho le. The cu ttings arecollected in a p lastic lined p it for d isposa l.

Dr illing mud is a m ixture of wa ter, c lay and spec ial minera l and chem icals. Dr illing mudremoves cu tting from the ho le and coo ls and lubr icate the dr illing b it. Mud a lso ma intain

pressure inside the ho le to keep the f luid in the forma tion from en ter ing the ho le and produc ing a gusher of o il on the surface. D ifferen t muds are used dur ing the dr illing processto ad just the rock forma tion, tempera ture and pressure.

(D)PO W ER:

A dr illing r ig needs power to opera te the c irculating, ro tating, and ho isting sys tems. Th is power comes from two or more d iesel engines. Power is transmitted to the dr illing r ig fromeither genera tors that prov ide e lectr icity or mechan ical dr ivers that use a ser ies of pu lleys and

belts to transm it power from the eng ines to the componen ts that requ ire the power.


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The Dr illing Crew:

D rilling is done by a service company or drilling contractor. Thedrilling crew is composed of:-

y Too l pusher :-The tool-pushe r , the location superv isor for the dr illingcontractor, is usua lly a sen ior, exper ienced individua l who hasworked h is way up through the ranks of the dr illing crew

pos itions. H is job is large ly adm inistrative, including ensur ingthat the r ig has suff icient mater ials, spare par ts and sk illed

personne l to con tinue eff icient opera tions.

y Dr iller :-The d riller is the superv isor of the r ig crew. The dr iller is respons i ble for the eff icient opera tion of the r ig-s ite as we ll as the safe ty of the crew. He typically has many years of r ig-site exper ience and has worked h is way up from o ther jobs. Wh ile the dr iller mus t know how to perform each of the jobs on the r ig, h is or her ro le is to superv ise the work and con trol the ma jor r ig sys tems. The dr iller opera tes the pumps, draw-works, androtary table via the dr illers conso le-a con trol room of gauges, con trol levers, rheos tats,and o ther pneuma tic, hydrau lic and e lectron ic instrumen tation. The dr iller also opera testhe draw-works brake us ing a long-hand led lever. Hence, the dr iller is some timesreferred to as the person who is "on the brake.

y Derr ickman:-The d errickman is in charge of the mud-process ing area dur ing per iods of c ircu lation.The derr ickman a lso measures mud dens ity. The derr ickman repor ts to the tool-pusher,

but is instruc ted in detail by the mud eng ineer on wha t to add to the mud, how fas t andhow much. H is other job is to hand le pi pe in the derr ick wh ile pu lling ou t or runn inginto the ho le. One of the r ig crew members who ge ts his name from the fac tthat he

works on a p latform a ttached to the derr ick or mas t, typically 85 f t [26 m] above the r igf loor, dur ing tr i ps. I n a typical tr i p out of the ho le, thederr ickman wears a spec ial safe ty harness that enab les himto lean ou t from the work p latform (ca lled the monkey

board) to reach the dr ill pi pe in the cen ter of the derr ick or mast, throw a line around the p i pe and pu ll it back into itsstorage location (the f ingerboards) un til it is time to run the

pi pe back into the we ll. I n terms of sk ill, phys ical exer tionand perce ived danger, a derr ickman has one of the mos t demand ing jobs on the r ig crew. Some modern dr illing r igs

have au tomated p i pe-hand ling equ i pmen t such that the derr ick-man con trols themach inery ra ther than phys ically hand ling the p i pe. I n an emergency, the derr ick-man

can qu ick ly reach the ground by an escape line of ten ca lled the Geron imo line.

y Motorman :-The motorman is respons i ble for ma intenance of the eng ines. Wh ile all members of ther ig crew he l p with ma jor repa irs, the mo torman does rou tine preven tive ma intenanceand m inor repa irs.


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y R oughnecks :-A roughneck is a low-rank ing member of the dr illing crew. The roughneck usua lly

performs sem isk illed and unsk illed manua l labor that requ ires con tinua l hard work indiff icult cond itions for many hours. Af ter roughnecks unders tand how the r ig opera tesand demons trates their work e thic, they may be promo ted to other pos itions in the crew.

y R oustabou ts :-A roustabout is any unsk illed manua l laborer on the r ig-s ite. A rous tabou t may be par t of the dr illing con tractor's emp loyee workforce, or may be on location temporar ily for spec ial opera tions. R oustabou ts are common ly hired to do the per i phera l tasks, rang ingfrom c leaning up location to cleaning threads to digging trenches to scrap ing and

painting r ig componen ts.

PRODUCTION OF OIL :

Produc tion is the opera tion that br ings hydrocarbons to the surface and prepares them for process ing. Produc tion beg ins af ter the we ll is dr illed. The m ixture of o il, gas and wa ter fromthe we ll is separa ted on the surface. The wa ter is disposed of and the o il and gas are treated,measured, and tested. Produc tion opera tions include br inging the oil and gas to the surface,maintaining produc tion, and pur ifying, measur ing, and testing.

The var ious s teps invo lved in produc tions are as be low:-

CON STRUCTION OF W ELL:-

Af ter a we ll has been dr illed, it must be comp leted before o il and gas produc tion can beg in.The f irst step in this process is installing casing pipe in the we ll.

Cas ing :- Cas ing is a p i pe usua lly larger in diame ter and longer than dr ill pi pe and is used to line the ho le.Cas ing that is cemen ted in place a ids the dr illing

process in severa l ways :

a) Preven t contamination of fresh wa ter we ll zones.

b) Preven t uns table upper forma tions from cav ing- inand s tick ing the dr ill str ing or form ing large caverns.

c) Prov ides a s trong upper founda tion to use h igh-dens ity dr illing f luid to con tinue dr illing deeper.


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d) Isolates differen t zones ( that may have d ifferen t pressuresor f luids - known as zona l isolation) in the dr illed forma tions from oneanother.

e) Sea ls off h igh pressure zones from thesurface, avo iding po tential for a b lowou t

f) Preven ts f luid loss into or con tamination of produc tion zones.

g) Prov ides a smoo th interna l bore for installing produc tion equ i pmen t

A slightly differen t metal str ing, ca lled produc tion tubing, is usua lly used w ithout cemen t in the sma llest cas ing of a we ll comp letion to con tain produc tion f luids andconvey them to the surface from anunderground reservo ir.

Oil and gas o il usua lly requ ire four concen tr iccas ings :-

1) Conduc tor p i pe2) Surface cas ing3) I ntermed iate cas ing4) Produc tion cas ing

The conduc tor cas ing serves as a suppor t dur ingdr illing opera tions, to f lowback re turns dur ing dr illing and cemen ting of the surface cas ing,

and to preven t collapse of the loose so il near the surface.It can norma lly vary from s izes suchas 18" to 30".

The purpose of surface cas ing is to isolate freshwa ter zones so that they are no tcontaminateddur ing dr illing and comp letion. Surface cas ing is the mos t str ictly regu lated due to theseenvironmen tal concerns, wh ich can include regu lation of cas ing dep th and cemen t qua lity. Atypical size of surface cas ing is 13 ".

I ntermed iate cas ing may be necessary on longer dr illing interva ls where necessary dr illingmud we ight to preven t blowou ts may cause a hydros tatic pressure that can frac ture deeper forma tions. Cas ing p lacemen t is selected so that the hydros tatic pressure of the dr illing f luidrema ins be tween forma tions pores and frac ture pressures.

The f inal interva l is produc tion cas ing. As w ith the cas ing interva ls descr i bed above, the produc tion cas ing s tr ing ex tends to the surface where it is hung off. As the sma llest casing, it will former the ou ter boundary of the 'A' annu lus, wh ich may involve it being used for gas lif t and we ll k ills. A typical size is 9 ". The produc tion cas ing or o il str ing is the f inal and innermos t cas ing for mos t wells. The produc tion cas ing comp letely sea ls off the produc ing forma tion from wa ter aqu ifers


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The pro d uction casing runs to the bo ttom of the ho le or stops just above the produc tion zone.U sua lly, the cas ing runs to the bo ttom of the ho le. The cas ing and cemen t sea l off thereservo ir and preven t f luids from leaving. I n this case the cas ing mus t be perfora ted to a llowliquids to f low into the we ll. Th is is a perfora ted comp letion. Mos t wells are comp leted byusing a perfora ted comp letion. Perfora ting is the process of p iercing the cas ing wa ll and thecemen t behind it to prov ide open ings through wh ich forma tion f luids may en ter the we ll bore.

I n order to reduce cos t, a liner may be used wh ich ex tends just above the shoe (bo ttom) of the prev ious cas ing interva l and hung off downho le rather than a t the surface. I t may typically be7", a lthough many liners ma tch the diame ter of the produc tion tubing.

Few we lls actually produce through cas ing, s ince produc ing f luids can corrode s teel or formdepos its such as aspha ltenes or paraff ins and the larger d iame ter can make f low uns table.Produc tion tubing is therefore installed inside the last cas ing s tr ing and the tubing annu lus isusua lly sea led a t the bo ttom of the tubing by a packer. Tub ing is eas ier to remove for maintenance, rep lacemen t, or for var ious types of workover opera tions. Tub ing issignif ican tly lighter than cas ing and does no t requ ire a dr illing r ig to run in and ou t of ho le;sma ller pu lling un its are used for this purpose.

TU BE AND PACKER S:-Af ter cemen ting the produc tion cas ing, the comp letion crewruns a f inal str ing of p i pe ca lledthe tubing . The we ll f luids from the reservo ir to the surface through the tubing. Tub ing issma ller in diameter than cas ing. The ou tside d iame ter ranges from abou t 1 to 4-1 /2 inches.

A packer is a r ing made of me tal and rubber that f itsaround the tubing. I t prov ides a secure sea l betweenevery thing above and be low where it is set. I t keepswell f luids and pressure away from the cas ing above it.

Since the packer sea ls off the space be tween the tubingand the cas ing, it forces the forma tion f luids into and upthe tubing.

Surface safe t y valve:- A subsurface safe t y valve isinstalled in the tubing s tr ing near the surface. The va lverema ins open as long as f luid f low is norma l. When thevalve senses some thing am iss w ith the surface equ i pmen t of the we ll, it closes, preven ting the f low of f luids.


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W ELL HEAD:-

The we llhead includes a ll equi pmen t on the surface thatsuppor tsthe var ious p i pe s tr ings, sea ls off the we ll, and con trols the pa thsand f low ra tes of reservo ir f luids.

They cons ist of : 1. Cas ing heads2. Cas ing hanger 3. Tub ing head4. Tub ing hanger 5. Chr istmas tree

The var ious par ts are d iscussed as be low:-

C ASING HEA D:-

Cas ing head is heavy s teel f itting a t the surface, from wh ich each s tr ing of cas ing usua llyhangs. Me tal and rubber sea ls in the cas ing head preven t f luids from mov ing within thewellhead or escap ing to the a tmosphere. Each cas ing head a lso hasa p lace for a pressuregauge to warn of leaks. The lowes t par t of the we llhead is almost always connec ted to thesurface cas ing str ing, and prov ides a means of suspend ing and pack ingoff the nex t cas ing s tr ing. Prov iding a ttachmen t to the surface cas ingstr ing through the type of bo ttom connec tion (S li p-on-we ld, threaded,Sli ploc), the cas ing head is typically qua lif ied to withstand up to10,000 ps i work ing pressure. I t suspends the cas ing and packs off the

next casing s tr ing wh ile prov iding annu lar ou tlets, as we ll assuppor ting the BOP wh ile dr illing the rema ining s tages.

C ASING HA NG E R:-

The cas ing hanger is that por tion of a we llhead assemb ly wh ich prov idessuppor t for the cas ing s tr ing when it is lowered into the we ll bore. I t serves toensure that the cas ing is proper ly located. When the cas ing s tr ing has beenrun into the we ll bore it is hung off, or suspended, by a cas ing hanger, wh ichres ts on a land ing shou lder inside the cas ing spoo l. Cas ing hangers mus t bedes igned to take the fu ll weight of the cas ing, and prov ide a sea l between thecas ing hanger and the spoo l.

TU B ING HEA D:- The tubing head suppor ts the tubing s tr ing, sea ls off pressure be tween the cas ing and the inside of tubing and prov ides connec tions a t the surface to con trol the f lowing liquid or gas. The tubing headof ten s tacks above the uppermos t casing head. L ike the cas ing heads, it has ou tlets to allow access tothe annu lus for gaug ing pressure or connec ting va lves and f ittings to con trol the f low of f luids.


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C H RISTM AS TR EE :-We lls are equ i pped w ith a group of va lves and f ittings ca lled a Chr istmastree. The va lves and f ittings are used to regu late, measure, and d irect thef low of hydrocarbons from the we ll.Gauges measure pressure in the cas ing and in the tubing. Va lves con trol the f low of hydrocarbons from the we ll. The choke con trols the ra te of

produc tion from the we ll.

STA R T OF FLOW

Before o il produc tion can beg in the dr illing mud mus t be removed from inside the cas ing.Salt water is pumped into the tubing to remove this mud. I n some cases the we ll has too muchsalt water in the tubing and some mus t be pumped ou t. Produc tion f low can a lso be s tar ted

by forc ing h igh-pressure gas into the tubing.

Some times af ter star ting the f low the we ll does produce a t a fast enough ra te. I n this situation,f low from the reservo ir may be increased by s timulation. S timulation is one of severa l

processes that enlarge or crea te channe ls in the reservo ir rock so that the oil and gas canmove through it and into the we ll.

Gas we lls are genera lly comp leted in the same way as o il wells excep t that natura lgas usua llyf lows w ithou t hel p from the we ll.

Dr ive mechan isms:

(a)Na tural dr ive:

Af ter the we ll has been comp leted, the hydrocarbons f low from the reservo ir to the surface.I n the f irst stage of a reservo ir's produc ing life, pressure

from the reservo ir forces the hydrocarbons from the poresin the forma tions, moves them to the we ll, and up to thesurface. Th is stage of produc tion is known as pr imaryrecovery. The three pr inci pa l pr imary recovery dr ivemechan isms are wa ter dr ive, gas dr ives, and grav itydra inage.

Wa ter dr ive uses the pressure exer ted by wa ter be low theoil and gas in the forma tion to force hydrocarbons ou t of


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pump, where the injected fluid passes through a nozzle creating a jet effect pushing the produced fluids to surface.These systems are very versatile and have been used in shallow depths ( 1000 ft) to deeper wells ( 1 8,000 ft), low rate wells with production in the 10 s of barrels per day to wells

producing in excess of 10 ,000 barrels per day ( 1 ,600 m/d). In addition to this certain fluidscan be mixed in with the injected fluid to help deal or control with corrosion, paraffin and

emulsion problems. They are also suitable for wells where conventional pumps such as therod pump are not possible due to crooked or deviated wells.These systems have also some disadvantages. They are sensitive to solids and it is the leastefficient lift method. While typically the cost of deploying these systems has been very high,new coiled tubing umbilical technologies are in some cases greatly reducing the cost.

E SP Electric Submersible Pumps consist of a) a downhole pump, which is a series of centrifugal

pumps, b) a separator or protector, which function is to prevent that produced fluids enter theelectrical motor, c) the electrical motor, which transforms the electrical power into kineticenergy to turn the pump, and d) an electric power cable that connects the motor to the surfacecontrol panel. ESP is a very versatile artificial lift method and can be found in operatingenvironments all over the world. They can handle a very wide range of flow rates (from 2 00 to 90 ,000 barrels per day) and lift requirements (from virtually zero to 10 ,000 ft (3, 000 m) of lift). They can be modified to handle contaminants commonly found in oil, aggressivecorrosive fluids such as H2S and C 2, and exceptionally high downhole temperatures.Increasing water cut has been shown to have no significant detrimental effect on the ESP

performance. It is possible to locate them in vertical, deviated, or horizontal wells, but it isrecommended to deploy them in a straight section of casing for optimum run life

performance. Although latest developments are aimed to enhance the ESP capabilities tohandle gas and sand, they still need more technological development to avoid gas locked andinternal erosion. Until recently, ESP's have come with an often prohibitive price tag due tothe cost of deployment which can be in excess of $2 0 ,000 .

Gas L iftGas Lift is another widely used artificial lift method. As the name denotes, gas is injected inthe tubing to reduce the weight of the hydrostatic column, thus reducing the back pressureand allowing the reservoir pressure to push the mixture of produce fluids and gas up to thesurface. The gas lift can be deployed in a wide range of well conditions (up to 3 0 ,000 bpd anddown to 1 5,000 ft). They handle very well abrasive elements and sand, and the cost of work over is minimum. The gas lifted wells are equipped with side pocket mandrel and gas liftinjection valves. This arrangement allows a deeper gas injection in the tubing. The gas liftsystem has some disadvantages. There has to be a source of gas, some flow assurance

problems such as hydrates can be triggered by the gas lift.

PC

P Progressing Cavity Pumps, P CP, are also widely applied in the oil industry. The P CP consists

of a stator and a rotor. The rotor is rotated using either a top side motor or a bottom holemotor. The rotation created sequential cavities and the produced fluids are pushed to surface.The P CP is a flexible system with a wide range of applications in terms of rate( up to 5, 000

bpd and 6, 000 ft). They offer outstanding resistance to abrasives and solids but they arerestricted to setting depths and temperatures. Some components of the produced fluids likearomatics can also deteriorate the stator s elastomer.


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R od P umpsRod Pumps are large cylinders with both fixed and moveable elements inside. The mostimportant components are: the barrel, valves (traveling and fixed) and the piston. It also hasanother 1 8 to 3 0 components which are called "fitting ". The pump is designed to be insertedinside the tubing of a well and its main purpose is to gather fluids from beneath it and liftthem to the surface.

C omponentsEvery part of the pump is important for its correct operation. The most commonly used partsare described below:- Barrel : The barrel is a large cylinder which can be from 10 to 36 feet long anda diameter from 1 .25 to 3.75 inches (95 mm). After using several materials for itsconstruction, the AP I (American Petroleum Institute) standardized the use of 2 materials or compositions for this part which are carbon steel and brass , both with an inside coatingof chrome . The advantage of brass against carbon steel, weather is a more soft material, is its100% resistance to corrosion .- Piston/Plunger : This is a nickel-metal sprayed steel cylinder, that goes inside the barrel. Itsmain purpose is to create a sucking effect that lift the fluids beneath it and then, with the helpof the valves, take that fluids above it and, progressively, out of the well. It achieves this witha reciprocal up and down movement.- Valves : The valve has two components - the seat and the ball - which create a complete sealwhen closed. After trying several materials, the most commonly used seats are made of carbon nitride and the ball is often made of silicon nitride. In the past, balls of iron, ceramicand titanium were used. This last type of balls, made of titanium, are still being used but onlywhere crude oil is extremely dense and/or the quantity of fluids is too much. The mostcommon configuration of a rod pump, requires two valves, called the traveling valve andfixed or static valve.- Piston rod : This is a rod that connects the piston with the outside of the pump. Its main

purpose is to transfer the energy produced by the " Nodding Donkey " above in an up/downreciprocal movement.- Fitting: The rest of the parts of the pump is called fitting and is, basically, small piecesdesigned to keep everything hold together in the right place. Most of these parts, are designedto let the fluids pass uninterrupted.- Filter : The job of the filter, as guessed, is to stop big parts of rock, rubber or any other garbage that might be loose in the well from going into the pump. There are several types of filters, being a common iron cylinder with enough holes in it to permit the entrance of theamount of fluid the pump needs the most commonly used.

(c)ENHAN CED O IL RE COVERY :

After a well has used up the reservoir's natural drives and gas lift or pumps have recovered allthe hydrocarbons possible, statistics show that 25 to 95 % of the original oil in the reservoir may still be there. This amount of oil can be worth recovering if prices are high enough. Themajor methods of i d il ! y are w " t # fl di $ % , % " & i ' j ( ) ti 0 ' , chem i ca l

fl 1 1 di 2 3 , and t herma l recover y. These techniques are used when production from the wellstarts to decrease.


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W ater-

4

loo d ing is a technique where wa ter is in jected into the forma tion us ing we lls that have ceased produc tion. The in jected wa ter en ters the reservo ir and d isplaces some of therema ining o il toward produc ing we lls in the same reservo ir. The produc ing we lls then pump

up the oil and wa ter. Severa l in jection we lls surround each produc ing we ll. Wa ter f lood ing isthe least expens ive and mos t widely used secondary recovery me thod.Produc tion can a lso be increased by in jecting gas, such as na tural gas or n itrogen, into thereservo ir. The in jected gas expands to force add itiona l volumes of o il to the surface.

C hemical f loo d ing uses spec ial chemicals in water to push o il out of the forma tion. Thesechem icals act as sur f actants that cause the oil and wa ter to mix and break the o il into tinydrop lets that can be more eas ily moved through the reservo ir to the we ll. T hermal recover 5 is used when the o il is so v iscous, or thick, that it canno t f low through thereservo ir and into a we ll. When the o il is hea ted, its viscos ity is decreased and the f lowincreases. R ecovery techn iques that use hea t are ca lled therma l processesor therma l recovery.

S team Drive or steam injection invo lves genera ting s teamon the surface and forc ing this steamdown in jection we lls and into thereservo ir. When the steam en ters thereservo ir, it heats up the oil andreduces its viscos ity. The hea t fromthe steam a lso causes hydrocarbons toform gases wh ich a lso increases f low.The gases and s team prov ideadditiona l gas dr ive and the ho t water also moves the thinned o il to

produc tion we lls.


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Another way to use heat in a reservoir is fi re fl oo di 6 7 , or i 6 8 it 9 (in-place) combustion. Infire flooding, the crew ignites a fire in place in the reservoir. They inject compressed air down an injection well and into the reservoir. A special heater in the well starts a fire. As thefire burns, it begins moving through the reservoir toward production wells. Heat from the firethins out the oil around it, causes gas to vaporize from it, and changes water in the reservoir to steam. Steam, hot water, and gas, all act to drive oil in front of the fire to production wells.

M i crob i a l i j ec ti on

Microbial injection is part of microbial enhanced oil recovery and is presently rarely used,

both because of its higher cost and because the developments in this field are more recentthan other techniques. Strains of microbes have been both discovered and developed (usinggene mutation) which function either by partially digesting long hydrocarbon molecules, by

generating bio-surfactants, or by emitting carbon dioxide .

Three approaches have been used to achieve microbial injection. In the first approach, bacterial cultures mixed with a food source (a carbohydrate such as molasses is commonlyused) are injected into the oil field. In the second approach, used since 1 985, nutrients areinjected into the ground to nurture existing microbial bodies ; these nutrients cause the

bacteria to increase production of the natural surfactants they normally use to metabolizecrude oil underground. After the injected nutrients are consumed, the microbes go into near-shutdown mode, their exteriors become hydrophilic, and they migrate to the oil-water interface area, where they cause oil droplets to form from the larger oil mass, making thedroplets more likely to migrate to the wellhead. This approach has been used in oilfields near the Four Corners and in the Beverly Hills Oil Field in Beverly Hills, California.

The third approach is used to address the problem of paraffin components of the crude oil,which tend to separate from the crude as it flows to the surface. Since the Earth's surface isconsiderably cooler than the petroleum deposits (a temperature drop of 1 3-1 4 degree F per

thousand feet of depth is usual), the paraffin's higher melting point causes it to solidify as it iscooled during the upward flow. Bacteria capable of breaking these paraffin chains into

smaller chains (which would then flow more easily) are injected into the wellhead, either near

the point of first congealment or in the rock stratum itself.

Thus these are a few processes by which the oil can be recovered to maximum possible

extent.


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TR ANSPO R TAT ION OF O I L

Crude o il must be moved from the produc tion s ite to ref iner ies and from ref iner ies toconsumers. These movemen ts are made us ing a number of d ifferen t modes of transpor tation.Crude o il and ref ined produc ts are transpor ted across the wa ter inbarges and t ankers . On

land crude o il and produc ts are moved us ing pi pe lines, trucks, and trains.

Wa terborne Transpor tation

Crude o il tankers are used to transpor t crude o il from f ields in the M iddle Eas t, Nor th Sea,Afr ica, and La tin Amer ica to ref iner ies around the wor ld. Produc t tankers carry ref ined

produc ts from ref iner ies to terminals. Tankers range in size from the sma ll vesse ls used to transpor t ref ined produc ts to huge crude carr iers. Tanker s izes are expressedin terms of d ea d weight (d wt ) or cargo tons. The sma llest tankersare G eneral P urpose which range from 10 to 25,000 tons. These tankers are used to transpor t ref ined produc ts. The L arge

Range and V er @ L arge C ru d e C arriers (VL CC ) are emp loyed in interna tiona l crude o il trade.The s ize of tanker that can be used in any trade (commerc ial voyage be tween a por t of or iginand des tination) is dependen t on the tanker's length and loaded dep th and the s ize of theloading and un loading por ts.

Land transpor tation P ipelines are the mos t eff icient method to transpor t crude o il and ref ined produc ts. Pi pelinesare used to move crude o il from the we llhead to ga ther ing and

process ing fac ilities and from there to ref iner ies and tanker loading fac ilities. Produc t pi pelines sh i p gaso line, jet fuel, anddiesel fuel from the ref inery to loca l distr i bution fac ilities.

Crude o il is co llected from f iel d gathering sA stems cons isting of pi pelines that move o il from the we llhead to storage tanks andtreatment facilities where the o il is measured and tested. From thegather ing sys tem the crude o il is sen t to a pump s tation where the

oil delivered to the pi peline.

The p i peline may have many co llection and de livery po ints along rou te. Boos ter pumps arelocated a long the p i peline to ma intain the pressure and keep the oil f lowing. The de livery

points may be ref iner ies, where the o il is processed into produc ts, or sh i pping terminals,where the oil is loaded on to tankers.

A pi peline may hand le severa l types of crude o il. The p i peline w ill schedu le its opera tion toensure that the r ight crude o il is sen t to the correc t destination. The p i peline opera tor se ts the


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date and p lace when and where the o il is rece ived and the when the o il will arr ive at itsdestination. Crude o il may a lso move over more than one p i peline sys tem as it journeys fromthe oil f ield to the ref inery or sh i pping por t. Storage is loca ted a long the p i peline to ensuresmoo th con tinuous p i peline opera tion.

Af ter crude o il is conver ted into ref ined produc ts such asgaso line, p i pelines are used to transpor t the produc ts toterminals for movemen t to gaso line s tations. I n add ition togaso line, produc ts pi pelines are used to shi p diesel fuel, homeheating fue l, kerosene, and jet fuel. Because produc t pi pelinesare used to move many d ifferen t produc ts, the differen t typesof produc ts are sh i pped in batches .

Batching is used to move two or more d ifferen t liquids through the same p i peline. The liquidare transpor ted in a ser ies of ba tches. The ad joining ba tches m ix where they come intocontact. Th is mixed s tream may be sen t to ref inery for re-ref ining, so ld as a lower va lued

produc t such as a m ixture of prem ium un leaded gaso line w ith regu lar un leaded gaso line, or sold as m ixture. Many produc t pi pelines have s tandard produc t spec if ications. Th is allowsone company to sh i p gaso line over the line and ge t not be concerned whe ther he rece ivesgaso line from that same ba tch. I ts all the same qua lity. I ndividua l add itive packages areadded a t the distr i bution terminals.

Finally the conver ted and processed produc ts f ind their way to the marke t.

ECONOMY :

Drilling costs :

The dr illing company opera tes in accordance w ith a con tract which spec if ies that the we ll will be dr illed to a spec if ic dep th. The con tractor is pa id on a per day or per foo t dr illing ra te.

I n 2006 it cost $2.238 m illion to dr ill an o il well and $1.936 m illion to dr ill a na tura l gas we ll.The average cos t to dr ill a we ll was $324 /foot of dep th.

The average cos t to f ind and deve lop an o il and gas proper ty in the U nited States was$17.01 /BOE from 2005-2007. The cos t for onshore deve lopmen t was $13.38 /BOE and for offshore deve lopmen t was $49.54 /BOE. BOE is the barre ls of o il equivalent.

Dr illing cos ts have increased as o il pr ices have and dr illing ac tivity have r isen. I n 2000,when o il pr ices were $26.72 /B, dr illing cos ts were $593 thousand per o il well and$126 /foot. For 2006, when pr ices averaged $59.69 /B, dr illing cos ts were $2.238 m illion per oil well and $402 /foot.

P roduction costs :


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Production or lifting costs are the expenses associated with bringing oil and gas from thereservoir to the surface, separating the oil from any associated gas, and treating the producedoil and gas to remove impurities such as water and hydrogen sulfide.

Worldwide lifting costs have been increasing since 2 001 and U.S. costs have been higher than foreign cost since 2 00 4. In 200 7, U.S. production costs were $ 11 .25/barrel of oilequivalent (BOE) and foreign costs averaged $8.88/BOE. These figures include productiontaxes of $2.9 0 /BOE in the United States and $2.4 1 /BOE internationally.

S hipping costs:


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BIBL IOG RAP HY

1) www. p t ost t gi s .com 2) www. np g oup .com 3) www.w ikip di .o g 4) www.e xplo tionist .com 5) www. dm e.q ld .gov .a u

6) www.f m ct ech nologi e s.com 7) www. gloss ary. oil f ie ld .slb .com 8) www.h o w stu ffw o rks .com


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Upstream Processing