1.0 Hoisting systems

The hoisting system consists of surface equipment required to give the drill

string the necessary axial power, lifting speed and height.

Let us take a close look at this definition what it says that we require a tensioning

force of a certain size to perform the tasks required of the drill string. This is

however not sufficient as we require a certain speed of elevation with and

without load and this will include requirements for control of lowering speed. If

a hoisting system is to be effective we need a minimum lifting or working

height.

Main components of the hoisting system;

Derrick

Draw works and wire

Crown block/running block and elevator

Derrick’s foundation

1.1 Drilling derrick

- Designed for lifting and lowering equipment

- Has a fixed crown block at the top and a traveling block having a specific

working height and defined by the height of the derrick.

- Must be capable of carving the drill string’s weight and casing.

- Also acts as a drifting facility for all surface equipment on a well such as the

blow out preventers, riser and sea bed template.

Types of derricks

- Standard derrick (four legged frame work)

- Prilling mast (two structural beams a.k.a mobile mast)

- Hydrallic drilling mast (with derrick draw works, wire and blocks) replaced

by a hydrallic lifting device.

The design of the derrick should withstand the main stress listed below;

- Compression

- Wind

- Reactive force to the toque from the top drive

The derrick is designed to store a certain number of connected drill pipe lengths known

as stands.

About 90ft (28m) above the drill floor is a finger board for stacking and securing the

stands and the upper manipulator arm.

The derrick is equipped with guide beams for;

- guiding the block and top drive

- absorbing the toque when rotating the drill string

1.2 Draw works and wire

- to hoist and lower the drilling machine and drill string up and down the

derrick.

- Hydraulically driven draw works operate by use of

- Hydraulic pumps with oil flowing in the pumps being regulated from 0-100%

and choked to relate the equipment in either direction and the pumps being

angled out allowing the pump rotor to rotate without oil being fed to the

supply when there is no demand for oil to the system.

- Hydraulic motors which rotate the drum via two gear boxes the speed of the

drum is varied by altering the displacement volume to the motors and this is

controlled by an electro hydraulic proportion value which uses a

programmable logic system (PLS) which processes information from a

number of sensors placed around the system. All electrical signals from the

sensors in the system go via the PLS and out to the electric hydraulic values

that the PLS is programmed to control.

- The by pass values whose purpose is to be able to lower the winch very

quickly without being dependent upon the pump’s capacity. It is only used

when lowering the load as the tension will draw down any spare wire.

- Disc Brake (Parking brake)

In normal operations of the winch, the drum is controlled by adjusting the

displacement volume of motors. Disc breaks are primarily parking brakes but

can also be used for emergence braking. They work as a fail safe device

meaning that if a fault occurs in the control system or electrical supply is lost

the brakes are applied. To maintain the brake pressure, an accumulator is

installed on each brakeline which gives a signal to the PLS to indicate that

the brakes are off.

- Pressure lubricating system, this is for lubrication of the gear box which has a

nozzle for each pinion an electrically driven pump moves oil from the

reserviour through a filter and an oil cooler and into the nozzles a pressure

relief value is installed after the pump to control the system pressure.

- Emergence lowering of the hoist example is during a total shut down of the

control system, when the brakes cannot be operated, it is still possible to

lower the hoist. A hand pump can be connected to each brake to allow

lowering to be done manually. A ball value is installed in the line between

the normal hydraulic supply and the hand pump. This value is normally open,

but when the hand pump is to be used for lowering this value must be closed.

The hand pump is needed until the disk brakes gain enough pressure to be

released.

MODERN ELECTRICAL DRIVEN DRAW WORKS

There are basically two types;

1- Single speed gear driven (SSGD)

2- Active Heave Driven (AHD)

Both are powered by alternating current motors and consist of the following

components;

1. Man frame and housing – for mechanical protection and sound insulation.

2. Drum – manted on a bearing with a groove for wire

3. Gear box

4. Main break system which uses a variable speed drive system (VSDS) acting as a

generator to regenerate energy to the ac motor. The generated energy is fed into

the power distribution system providing braking force, counteracting the tension

forces during hoisting.

5. Disc brakes designed as parking and emergency brakes

6. Lubrication system, the gear boxes are equipped with a pressure lubrication

system for lubricating oil consisting of two electrically driven pumps and water

cooled heat exchangers lubrication with grease is restricted to the main bearings

and disk break mountings.

7. Electrical motors, the SSGD 500 has four motors in all whilist the AHD 1000

has six. The standard motors from his manufacture are diamensioned for 1150

HP, 600V and 1024A at 800rpm.

8. Air cooling system, the electrical motors are equipped with a fan system to

provide cooling air on each side of the draw cooks.

9. Control system, this consists of a control unit (draw works control cabinet) a

motion monitoring unit (MRU) which has an emergency stop and various field

instruments, pressure switches, temperature transmitters and position switches.

In addition, kinetic energy monitoring system (KEMS) software and a power

management system (PMS) are installed.

Basically, the use of the control system is as follows;

The traveling block speed is controlled by the driller giving a speed signal to

the control system by operating a joystick.

The control unit reprograms the speed signal to the required signals for the

operating system controlling motors. Simultaneously the control unit checks

the incoming speed signal against the motors performance curves, operational

limits and PMS to ensure that the draw works is operating within its limiting

values.

The VSDs ensures that the motors give the comect torque to achieve the

required block speed. This part of the control system adjusts the amount of

generated electrical energy from the motors during lowering so that the drum

can be applied with breaking force.

1.3 CROWN BLOCK AND TRAVELLING BLOCK

The traveling block is via hook or lifting blocks, the lifting equipment which carries the

load of the top drive and all that hanging from it and the drill line which passes between

the pulleys in the traveling and crown blocks. The number of pulleys in the block can

vary between four and seven all mounted on a common axle.

The crown block is fixed at the top of the derrick and is a simple open block

constructed with 4-7 pulleys on a common central axle. It acts as a hanger for the

traveling block and everything suspended from it.

The drilling line is wound around tie draw works drum and fixed to it by a fast line

anchor. Depending upon the size and type of the crown/traveling block, the line is

passed around the crown block 4-7 times through the pulleys. The wire is fixed to a

dead wire anchor with access for the reserve wire which is wound onto a storage drum.

1.4 DERRIC’S LOAD BEARING STRUCTURE

It is a foundation consisting of a beam frame upon which the drilling assembly is

installed. The derrick/drill floor must on an installation having several weeks be

adjusted to locate over beams known as skid beams.

2.0 ROTATING SYSTEM

The rotation system consists of that surface equipment necessary for exerting the

required torque and rotational speed on the drill string.

2.1 KELLY/ROTARY TABLE

The Kelly is also known as the drive pipe and is used in combination with the rotary

table.

The Kelly transfers the torque from the rotary table to the drill string and consists of the

following main components from top to down;

Swives with goose neck connection, hanging links and compressed air pipe

spinner.

The actual drive pipe, usually hexagonal section, 13-17m long.

The rotary Kelly bushing, with insets sized for the rotary table bearing, it is

equipped with an inner sleave which allows the Kelly to pass esily through

the bearing.

2.2 HYDRAULIC ROTARY TABLE

The rotary table is located at the drill center and is mounted into the actual deck. It may

be let into floor so that only the top is visible from the drill floor. The main function of

the rotary table is to rotate the complete drill string. It must also support the weight of

the drill string when hanging in the slips.

Other functions include; power slips, gear locking and lubrication. These have their

own hydraulic supply with a maximum pressure of 210 bar.

Power slips – they consist of several wedges arranged in a circle, gripping the

pipe and holding it fast. In addition to the two cylinders which squeeze the

slips together there are two single acting cylinders which centralize the sips

over the bore hole.

Gear locks – consists of the double acting hydraulic cylinders.

Lubrication of the rotational gears – they hydraulic motor drives a lubricating

pump and is single acting, meaning it only rotates in one direction.

2.3 TOP DRIVE DRILLING MACHINE (TDS/DDM) DERRICK

The most commonly used drilling method today it is a large drill which is screwed into

and rotates the whole drill string. In addition to the rotational motion of the top drive,

there are a number of the functions and tools which are incorporated to connect and

disconnect the drill string, and to handle the drillings process correctly.

A top drive is primarily made up of four main parts

Rotary swivel

Transmission system

Driver

Pipe handler

2.3.0 Pipe handler on the top drive drilling machine

Belted to the underside of the gear box. It has six main functions;

Hydraulic swivel and transfer of hydraulic lines and pneumatic lines.

Compensator links

Open and close arrangements of internal blow out preventer (IBOP) value

Torque wrench with lock

Elevator links (bails)

Elevator (pneumatically operated)

2.3.1 Hydraulic swivel (Positioning the elevator)

Mounted inside the pipe handler, shaped like a hollow axle. The rotation is controlled

by a double acting hydraulic motor so that it can revolve in both directions.

2.3.2 Compesator links

Its purpose is to prevent damage to the pipe threds during make up and breaking of the

drill pipe.

2.3.3 Elevator links (bails) – tilt function

Elevators are hinged steel devices with manual operating handles that crew members

latch onto tool joints will elevator links are cylindrical bars that support the elevators

and attach them to the hook.

2.3.4 IBOP Value

In principle is a ball value which opens and doses to allow the flow of drilling mud

through the drilling machine.

2.3.5 Torque wrench with locking function

On the pipe handler and is sued to screw together and unscrew the tool joints on the

drill pipe. It consists of two jaws or hydraulic tongs which close over and grip the pipe.

The lower tongs squeezes the lowest part of the drill pipe while the other doses around

the upper part. With the aid of two hydraulic cylinders it is possible to rotate the upper

relative to the lower. In this way it is possible to tighten the tool joints in the drill pipe

to a preset torque and unscrew them again when necessary.

2.4 Pipe handling system

The pipe handling system includes the surface equipment necessary for the

manipulation of pipes and drill string equipment, from storage on deck until it is made

up to the required torque in the rotary table.

Drill pipes are usually stored on the pipe deck and are transported from there to the drill

flow and onto a vertical position directly over the drill center.

Pipe handling machines include;

- Pipe deck machine (crane)

- Conveyor

- Pipe racking system

- Pipe handling arm

2.4.1 Pipe deck machine

Located on the pipe deck and its purpose is to lift pipes from the pipe deck and onto the

drill floor which is needed when running into the hole during the drilling process. When

tripping out of the hole the function is the reverse the pipe deck machine will only pick

up the pipes from the conveyor and replace them onto the pipe deck.

2.4.2 The conveyor

It is located between the pipe deck and the drill floor, and it is used to transport pipes

from the pipe deck to the drill floor.

2.4.3 Pipe racking system

The job of the drilling rig’s pipe racking system is to transport a stand of drill pipes

from the drill center and to a storage area (racking area) and on the other way round one

stand of pipes consists of two to four drill pipes coupled together. A stand is often

composed of three pipes screwed together having a height of 30m. The purpose of

storing pipes vertically in stands is to increase efficiency of the drilling process when

tripping in and out of the hole.

2.4.4 Pipe handling arm

The machine consists of primarily an upper arm and a lower arm with a finger board for

storing the pipes. The upper and lower arm are hydraulically independent of each other

as they are controlled from separate control panels by a PLS. seemingly, operators will

not appreciate that the arms are independent since they operate are joy stick and both

arms move together.

The lower arm has the job of lifting

Arm pipe stand whilst the upper arm guides the stand by its top.

2.4.4.1Lower arm

The lower arm has two primary functions and four claw functions i.e

1- Hoisting

2- Lower arm in and out

3- Claw (four)

All the above functions are controlled from a local control panel.

2.4.4.2 Upper arm

The upper arm has three primary functions and four claw functions.

1- Rotating the whole machine

2- Upper arm in/out

3- Tilt of the upper arm

4- Claw functions (four)

The above upper arm functions are also controlled from a local control panel.

2.4.5 Applying torque to the tool joint

Iron rough neck

Its job is to connect together and took the tool joints on the drill string. The iron rough

neck is a hydraulic power tong or power torque wrench.

The rough neck can be a drill floor works whose job is to screw together and disconnect

the drip pipe during drilling operations. They have to be screwed together with a pre

determined torque to prevent them from loosening inside the well, however this

involves a high risk of being injured and a source of many accidents.

A machine which can do this work was devised and became know as the iron rough

neck the machine can be operated locally, but on newer plat forms and rigs, it is

operated from an operator or driller’s cabin.

2.5 Other surface equipment

These are equipments which are more or less in continuous use and some equipment

which is used only in special situations.

2.5.1 Permanent surface equipment

1.5.1.1 Slips

They are composed of hang off wedges and their use is to hang off drilling and down

hole strings in theory table bushing. The wedges are assembled in arrow with several

internal gripping elements or dice for manual slips they come in several versions

depending on whether you are working with drill pipes collars or casing.

2.5.1.2 Mud buckets

Used to collect and remove mud when drill pipe stand tool joints are being unscrewed

when pulling out of the well.

2.5.1.3 Safety collar (dog coller)

When a relatively light or smooth pipe which may slide is hung off in the slips, it is

good practice to use a restraint known as a safety damp or dog collar.

It is simply used to prevent a hanging pipe sliding through the rotary table and falling

into the hole it is designed like a course linked chain with gripping elements facing into

the pipe surface and end claws with a close fitting bolt and not for tightening so that the

damp locks onto the pipe links can be removed or added in order to adjust to the pipe’s

diameter for various weights and sizes of pipe and casing.

2.5.1.4 Dope applicator

Dope lubricant and sealing compound for drill pipe took joints is normally applied

manually with a hand brush.

2.5.1.5 Tugger and winches for personal transport

For smaller lifting operations, the drill floor has a number of pneumatically driven

lifting winches the standard size for safe loading being 4t. The winch has a wire treaded

through single pulley block which is hug from the beam construction at the top of the

derrick.

2.5.2 Temporary surface equipment

These are only in use under special operations. The most important of these are;

Power elevator used when running casing and is pneumatically driven.

Side elevator manual and hinged so that one side savings out and the casing

is placed inside. The lock for the opening is secured with a locking pin.

Pick up elevator, light manual side door elevator for retrieving single pipes

from the conveyor.

Casing toughs, hydraulically operated wrench for screwing in and undoing

lengths of casing.

Cementing head a value which is mounted on top of the casing or drill pipe

for pumping cement slimy.