Slb Coil Tubing Services Manual

Schlum berger Dow ell

COILED TUBING SERVICES MANUAL

Section 210 Rev A - 98

COILED TUBING UNIT

1

2

3

4

5

Contents Page Introduction .................................................................................................... 2 COILED TUBING INJECTOR HEAD ............................................................... 2 1.1 Description ........................................................................................... 2 1.1.1 Principal Functions ............................................................................... 2 1.2 Features ............................................................................................... 3 1.2.1 Drive and Brake Systems .................................................................... 3 1.2.3 Traction and Tension Systems ............................................................ 11 1.2.4 Guide Arch Assembly ........................................................................ 13 1.2.5 Weight Indicator ................................................................................. 14 1.2.6 Depth Measurement Equipment ......................................................... 14 1.2.7 Stripper Mount ................................................................................... 14 COILED TUBING REEL ................................................................................ 15 2.1 Description ......................................................................................... 15 2.2 Features ............................................................................................. 16 2.2.1 Reel Drum .......................................................................................... 16 2.2.2 Reel Drive/Brake Systems ................................................................. 18 2.2.3 Reel Swivel and Manifold ................................................................... 19 2.2.4 Levelwind Assembly .......................................................................... 20 2.2.5 Tubing Measurement Accessories ...................................................... 21 2.2.6 Tubing Lubrication Equipment ............................................................. 21 2.2.7 Crash Protection Frame ...................................................................... 21 CT POWER PACK ........................................................................................ 21 3.1 Description ......................................................................................... 21 3.2 Features ............................................................................................. 22 3.2.1 Power-Pack Engine ............................................................................ 23 3.2.2 Hazardous Area Designation .............................................................. 23 3.2.3 Zone II Engine Protection Equipment ................................................. 23 3.2.4 Hydraulic Pumps ................................................................................ 24 3.2.5 Pressure Control Valves ..................................................................... 24 3.2.6 Hydraulic Fluid Reservoir .................................................................. 25 3.2.7 Filters and Strainers ........................................................................... 25 3.2.8 Hydraulic Fluid ................................................................................... 25 3.2.9 Accumulator ....................................................................................... 26 CONTROL CABIN ........................................................................................ 26 4.1 Description ......................................................................................... 26 4.2 Features ............................................................................................. 28 4.2.1 Injector Inside Chain Tension .............................................................. 28 4.2.2 Injector Outside Chain Tension ........................................................... 28 4.2.3 Injector-Head Drive ............................................................................. 29 4.2.4 Reel Controls ..................................................................................... 29 4.2.5 Lubrication Controls ........................................................................... 29 4.2.6 Engine Controls .................................................................................. 30 4.2.7 Blowout Preventers (BOP) ................................................................. 30 4.2.8 Strippers ............................................................................................ 30 4.3 Operating Technique ........................................................................... 31 4.4 Instrument Scanning .......................................................................... 32 CTU COMPONENTS - APPROXIMATE SIZES ............................................ 33

Page 1 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Introduction There are many different designs and configurations of CT unit. Most have evolved over a relatively short period as the understanding of criteria critical to the reliability of CT services have become better understood. In addition, the operating conditions in many geographical areas often determine the most appropriate CTU design. Regardless of manufacturer, model and design, every CTU comprises the following principal items.

Schlum berger Dow ell

The following functions apply to the majority of injector heads. • Pull the CT string • Push the CT string • Hold the CT string • Guide and support the CT string • Secondary/support functions include:

• Injector head • Weight indicator mount • CT reel • Depth system mount • Power pack • Stripper mount • Control cabin • Pressure control equipment

Pull (Tensile Force)

The following section provides an overview of these items of CT equipment, describing their function and principal components or subsystems.

The injector head pull capacity should be compatible with the weight of the CT string in use plus: • Effect of fluid density inside/outside the CT string

1 COILED TUBING INJECTOR HEAD

• Overpull (tension) to be applied at the BHA

1.1 Description

• Effect of drag (friction) caused by the string or BHA

The coiled tubing injector head provides the effort and traction necessary to run and retrieve the CT string into and out of a wellbore. Several hydraulic systems are used to enable the coiled tubing unit (CTU) operator to exercise a high degree of control over any CT string movement. A thorough understanding of the injector head control and monitoring systems is essential to ensure the equipment is operated efficiently, safely and without risk of damage to the well equipment, pressure control equipment, CT string or the CTU.

• Friction or drag created by the stripper(s)

1.1.1 Principal Functions

• Friction or drag created by the stripper(s)

The basic functions required of all CT injector heads includes safely pulling, pushing and holding the CT string under the specific wellbore and treatment conditions. However, there are several secondary or support functions that are vital to ensure safe and reliable CT operations.

Hold

Page 2 of 33

Push (Snubbing Force) The injector head snubbing capacity should be compatible with: • The force required to overcome the wellhead pressure • Acting on the cross-sectional area of the CT string

The injector head should be capable of safely holding the CT string stationary. This holding function should be available with the hydraulic systems or power pack in both

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

normal operating conditions and disabled modes. In addition, the transition from stationary to in-hole and out-of-hole modes should be smooth and easily controlled.

Guide the tubing Components of the injector head (guide-arch or gooseneck) serve to support and guide the CT string from the delivery (fleet) angle of the reel into the wellbore.

Section 210 Rev A - 98

The global CTU fleet includes several injector head models, the most common of which are shown below. The explanation of systems and components in this manual section will be generic although some of the more significant variations in design, specification and operation may be outlined. The principal features and components of injector heads are illustrated in Figures 1 through 5.

Weight indicator mount Injector heads are typically configured with the traction and drive components mounted on a “floating” inner chassis. This is contained within a fixed outer frame with the weight indicator sensor(s) connected between the two frames.

Depth system sensor The injector head provides a convenient mounting position for friction wheel depth measurement systems. At least two independent sensors are typically required on every CT operation, e.g., one reel mounted and one injector head mounted system.

The capacity (maximum pull) of an injector head is the major factor in determining the operating capability of the CTU. The table in Figure 5 summarizes the key performance data and specifications of common injector head models The principal components of an injector head can be categorized in the following systems or major assemblies. • Drive and brake system • Chain assembly • Traction and tension system

Stripper mount • Guide-arch assembly The primary stripper is generally permanently mounted to the injector head. Unless the injector head is otherwise supported, the mounting point bears all of the forces necessary to run and retrieve the CT string. The stripper mount also provides a reference point with which the drive chains and guide-arch are ultimately aligned.

In addition, secondary or support systems, include: • Weight indicator • Depth sensor mounts

1.2 Features

• Stripper mount

The design and configuration of injector heads have developed over several years to meet specifications which reflect the evolving nature of CT applications. The trend toward larger tubing sizes which enable greater circulation rates, requires the injector head be capable of handling a wider range of tubing. Similarly, since CT has commonly become the preferred intervention method in extended reach or horizontal wells, the “average string” length has increased in recent years. These factors, especially in combination, demonstrate the increased demands being placed on injector heads and other key items of CT handling equipment.

1.2.1 Drive and Brake Systems

Note: The injector head drive and brake systems are capable of exerting high forces on the CT string, wellbore tubulars or wellhead equipment. Significant damage may result if the systems are not operated, controlled or monitored correctly. Therefore, it is vital that the CTU operator is aware of the design and layout of the specific system in use. The operator must be familiar with the location and setting of the system control and relief valves. In addition, the limitations of the CT string must be understood when adjusting system pressures etc. to avoid the application of excessive force to the string.

Page 3 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Gooseneck

Lubricant reservoir

Stripper assembly

Injector drive motor

Inside chain tension system Accumulator Stripper assembly

Figure 1. Typical injector head.

Page 4 of 33

Schlum berger Dow ell

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Section 210 Rev A - 98

Figure 2. - Hydra-Rig HR 480.

Figure 3. - Hydra-Rig HR 440.

Figure. 4 Stewart and Stevenson SS 400.

Page 5 of 33

Section 210

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Rev A - 98

Schlum berger Dow ell

R T- 20 M A R I TI M E H YD R AU L I CS ( CA N) L TD . CA L G AR Y, ALB ERTA, CANA DA

Figure 5. Stewart and Stevenson SS 800.

Injector Model

Approximate Dimensions Height Width Depth Weight (in.) (in.) (in.) (lb)

Snub Pull Capacity (x1,000 lbs)

CT Size Range (in.)

HR240

164

52

55

7,800

20

40

1 to 1-3/4

HR260

180

52

55

9,200

20

60

1 to 2-3/8

HR440

80

52

55

6,750

20

60

1 to 2-3/8

HR480

109

60

60

11,200

40

100

1-1/4 to 3-1/2

SS 400

82

42

58

5,700

20

40

3/4 to 3-1/2

SS 800

82

42

58

6,125

20

80

3/4 to 3-1/2

Figure 6. Injector head specification table.

Page 6 of 33

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

All injector heads currently in common use are hydraulically driven using either two or four hydraulic motors. The motors are typically connected and synchronized through a gear system located at the top of the injector head. Drive is directed to the chain drive sprockets (one for each injector chain set) via the drive shafts located at the top of the injector head. The direction of rotation and speed of the motors is controlled and shifted by a four-way hydraulic control valve located on the CTU power pack. The functions of the hydraulic valve, plus the hydraulic system pressure and rate, are remotely controlled from the CTU control console. Protection devices, such as pressure relief valves and crossover relief valves, are installed in the system to protect the tubing and hydraulic components from damage due to operator error or component failure. The injector-head brake is generally mounted integral to the motor assembly and is hydraulically controlled. Hydraulic pressure is required to release the brake so the system is considered fail-safe in operation. Application of the brake is typically automatic and controlled by the drive system hydraulic pressure, i.e., the brake is applied when the drive system hydraulic pressure falls below a preset value.

Section 210 Rev A - 98

Some early injector heads are equipped with hydraulic brakes controlled manually from the control console. On early models of Uniflex injector heads, external pneumatically operated disc brakes were fitted. Several injector head hydraulic motors are equipped with an internal speed shift facility which provides a high/low gear option that can be selected remotely from the CTU the control console. Two speed capability allows the injector head to operate more efficiently with the available hydraulic power supply, i.e. supply pressure and rate. When set in low speed mode the injector drive motors can apply maximum torque or pulling force. In high speed mode, available pulling force is typically halved and the running speed doubled. The injector head drive system includes several components necessary for control and safety purposes. Almost all injector heads are equipped with two pilot-operated counterbalance valves, located on the injector drive system lines between the drive motors and the pressure filters. The valves function as load holding valves by closing the motor outlet line until a pilot pressure, obtained from the motor inlet line, is sufficient to open the valve. This arrangement enables a smooth transition between stationary and operating modes. In addition, it enables the weight of the CT string to be supported by the hydraulic fluid trapped by the counterbalance valve, effectively providing

Figure 7. CT chain assembly on tubing

Page 7 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

a fail-safe facility in the event of brake failure. The hydraulic lines between the counterbalance valves and the motor are high-pressure welded steel pipe. This is a safety feature since the line can contain hydraulic fluid at high-pressure while the string load is held by the counterbalance valve. High pressure filter assemblies are fitted on the injector head to protect the motor from extraneous materials which may be trapped during rig-up of the drive hose connections.

Schlum berger Dow ell

operating the pilot valve on the control console. These systems enable the operator to preset the maximum force that can be applied to the tubing. Some injector heads are offered with auto-driller control options. The purpose of auto driller control systems is to increase the operator’s ability to control the injector head at very slow speeds, such as may be encountered during drilling operations. Most systems also enable finer control of the force exerted on the tubing. 1.2.2 Chain Assembly

Hydraulic Supply System Overview Coiled tubing units are designed with two basic options for the primary injector drive hydraulic system, i.e., open or closed loop. Actual operation of the injector head and CTU differs little between the two systems, however, each system has associated advantages and disadvantages. System pressure is controlled by pilot operated relief valves located on each circuit. The maximum pressure for each circuit is preset by adjusting the relief valve (typically located on the power pack). The system pressure can then be controlled from zero up to the preset maximum by

The majority of injector heads are configured with two sets of opposing endless chains on which are mounted a series of gripper blocks. The gripping profile of each block is precisely shaped to suit a specific tubing size. To facilitate larger tubing sizes and the increasing range of sizes commonly used, chain designs with removable gripper inserts are commonly specified on most new injector heads. The gripper insert enable a range of tubing sizes to be run without the need to remove and replace the entire chain assembly. This facility reduces the time and effort required to reconfigure the injector head when running a different size of CT string. In addition, gripper inserts

Figure 8. HR240/260 chain assembly

Page 8 of 33

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Section 210 Rev A - 98

reduce the inventory items (quantity and cost) required for replacement when the gripper contact area becomes worn, or redressing when another tubing size is to be run. The force required for the chain to provide adequate grip on the tubing string is provided by the inside chain tensioner system (also known as the skate system or traction tensioner system). This force is applied to the back of the chain assembly. To enable the chains to rotate easily with relatively high loads applied, the chains are fitted with bearings which roll smoothly over the tensioner system components while transmitting the load.

predicted fatigue life of the string. Consequently, the effect of any components and equipment in contact with the string surface should be understood and carefully monitored.

Some special applications may require tapered OD string to be run, e.g., 1-1/2-in. and 1-3/4-in strings joined and hung off in a velocity string installation. The ability to change the chain gripper inserts as the tubing join passes through the injector head provides a clear advantage in such applications.

HR 240/260 Chain Assembly

The entire CT string load is held by the face of the gripper block or insert. This is often achieved under significant force. Therefore, the selection, operation and maintenance of chain components should be undertaken with a view to minimizing the risk of damage to the CT string and optimizing the life expectancy of consumable components. Recent studies indicate that even relatively light damage on the string surface can have a significant effect on the

The majority of chain systems are assembled from standard ANSI chain components and custom built parts enabling relatively easy replacement of worn or damaged items. The principal chain components and assemblies commonly found on injector heads are shown below. A relatively recent chain design featuring a single chain traction system is also included.

The HR 240/260 chain assembly incorporates a single piece gripper block design which is compatible with only one tubing size. This design was generally regarded as the industry standard until the introduction of chain with replaceable inserts. With the introduction of larger tubing sizes, a limitation of the single piece gripper resulted from the limited space afforded by the relatively small chain pitch used in early injector heads. Larger pitch chains were introduced on some injector head models, However, the flexibility of the insert chain system brought obvious advantages.

Figure 9. HR480 chain assembly.

Page 9 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Schlum berger Dow ell

Figure 10. SS800 chain assembly.

Figure 11. Dreco Chain Assembly - open.

Page 10 of 33

Figure 12. Dreco Chain Assembly - closed.

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

HR 480 Chain The HR 480 chain assembly incorporates carrier blocks each of which contains two gripper inserts. The inserts are supported by elastomeric elements which help ensure an even application of the gripping force transmitted to the CT string. This system is designed to reduce the risk of distorting the CT string when high loads are applied in deep or heavy-duty applications. The gripper block contact face is machined with a smooth surface and profile to minimize the risk of damaging the CT string surface. Gripper inserts are available in a range for 1-1/4-in. to 3-1/2-in. Gripper inserts are secured to the carrier block by a detent profile and held in place by a locking pin which locates through the side of the carrier block.

SS 800 Chain Stewart and Stevenson injector heads are equipped with the Varia-Block chain system which can be fitted with gripper inserts to suit a range of CT string sizes from 1-in. through to 3-1/2-in. The gripper insert is secured within the gripper block by a detent profile and locked in place by a

Section 210 Rev A - 98

spring loaded locking pin which protrudes from the carrier block into the back surface of the insert. The Varia-Block chain system is designed so the assembled chain has a flat back which rides on the rollers mounted on the chain tension or traction system, i.e., unlike conventional chains the Varia-Block chain assembly has no roller bearings.

DRECO Chain The DRECO chain and drive system features a unique single chain system. A hinged gripper assembly is housed in a carrier assembly (bucket) which in turn is attached to the drive chains. The chain assembly is aligned with the tubing axis thereby reducing eccentric loading on the chain and gripper components. In addition, the hinged gripper arrangement ensures that the gripping force is isolated from the drive chain components. These features are intended to provide smooth operation and long component life. Gripping force is applied to the tubing through the action of the hinged gripper block. The cam rollers on the griper block arms are forced closed by pressure beams which are in effect the equivalent of conventional skates or tensioner bars. Hydraulic rams are used to control the force applied by the pressure beams using a control and monitoring system similar to convention hydraulic tensioners. Chain Lubrication Injector head chains are submitted to significant forces and a high degree of movement during operation. To ensure the components function efficiently over an optimized chain life, efficient lubrication of moving components is required. This should be achieved without jeopardizing the essential friction between the tubing and the gripper block or insert. The lubricating oil is typically SAE 30, or equivalent. The fluid reservoir and control manifold are typically mounted on the injector head enabling the system to be remotely activated from the CTU control cabin. In addition to lubricating the chain components, the lubrication system is also sometimes used to lubricate the timing gears which synchronize the multiple motor and chain drive train. 1.2.3 Traction and Tension Systems

Figure 13. HR240/260 chain tension assembly.

The injector head traction or inside chain tensioner system, (also known as the skate system) provides the force

Page 11 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

required to securely grip the tubing in the chain gripper blocks. The necessary force is provided by a hydraulic system which is typically split into three distinct subsystems, i.e., top, middle and bottom traction systems. This enables some flexibility in operation and provides a high degree of contingency or back-up for one of the most important injector head functions. The inside chain tensioner pressure required during a CT operation is a function of the tubing load, size, condition, gripper-block condition and presence of oil or similar between the tubing and block. Since the consequences of attempting to run CT with too little inside tension on the chains can be catastrophic, the natural tendency of the operator is to apply excessive pressure to the system. While in operating terms this should ensure adequate control over the tubing slip, it will almost certainly be sufficient to significantly affect the life span of the injector chain bearings and the CT. The force is hydraulically applied through three separate sets of hydraulic cylinders. Each set is independently controlled and monitored from the control cabin. The use of three separate sets reduces the risk of a major operating failure should a component in the system fail.

Schlum berger Dow ell

To ensure adequate tension is maintained in the chain section outside the vertical drive plane, the injector head is fitted with an outside chain tensioner system. Current production injector-head models are equipped with a hydraulic tensioner system which is controlled and monitored from the control console. Hydraulic rams provide the tension by acting on the external idler gears. The idler gears are allowed to float horizontally allowing both chains to be tensioned with a single set of rams. Early injector head designs required that the tension be checked and adjusted manually through a mechanical adjustment mechanism. The chain tension applied is based on the injector-head manufacturer’s recommendations for the specific operating conditions. The outside chain tension is critical while the tubing is being injected with a negative load on the injector chains (while snubbing against high wellhead pressures). Damage to the CT string and chain drive components may result if outside chain tension is not properly applied under these conditions.

Recommended Guide Arch Radii Coiled Tubing OD (inches) 0.750 1.000 1.250 1.500 1.750 2.000 2.375 2.875 3.500

Typical Reel Core Radii (inches) 24 20-30 25-36 30-40 35-48 40-48 48-54 54-58 65-70

Typical Tubing Guide Arch Radii (inches) 48 48-54 48-72 48-72 72-96 72-96 90-120 90-120 96-120

Figure 14. Comparison of guide arch sizes and recommended guide arch radii.

Page 12 of 33

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Section 210 Rev A - 98

1.2.4 Guide Arch Assembly The gooseneck and pipe straightener (where fitted) act as a guide, turning the tubing through the angle between the wellhead and the CT reel. The CT string is supported by rollers located at ±10-in. intervals around the gooseneck circumference. The top rollers used to restrain the tubing are removable to enable easier installation and removal of tubing from the injector head. The guide arch rollers are typically profiled with a “V” of 120° and may be manufactured from steel, aluminum or polyurethane. Most guide arch designs incorporate a flared end which reduces the risk of damage to the tubing caused by misalignment when the tubing is being spooled to the edges of the reel drum. This is especially noticeable when the reel is located close to the injector head. The guide arch radius has a significant influence on the fatigue induced in the CT string, e.g., a 50 in. radius guide arch will have a more detrimental effect on tubing life than a 72-in. radius guide arch. Guidelines extracted from API RP 5C7 are shown in Figure 14 for various tubing sizes. The pipe straightener, where fitted, is located immediately above the injector head. It performs two main functions.

Figure 15. Weight indicator equipment.

Figure 16. Depth measurement equipment.

Page 13 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

• Ensures the tubing is as straight as possible before entering the injector-head chains.

Schlum berger Dow ell

1.2.6 Depth Measurement Equipment

• Guides the tubing cleanly into the injector-head chains, thereby reducing damage caused by misalignment.

Depth measuring equipment, electronic or mechanical, is frequently mounted on the injector head. Depth information is commonly gathered by two methods.

The pipe straightener generally consists of one adjustable roller located between two fixed opposing rollers.

• Mounting a friction-wheel-type counter assembly between the injector chains and stripper, or

1.2.5 Weight Indicator

• Mounting an encoder assembly to the injector-head chain drive shaft.

The weight-indicator load cell (or strain gage on electronic weight indicators) is typically located on the lower front edge of the injector head. The weight or load information is transmitted, from the load cell to the weight-indicator dial or display, either electronically or hydraulically. The injector-head frame is typically constructed in two distinct assemblies comprising the inner and outer frames (see Stripper Mount section). Pivot points between the frames enable the weight-indicator load cell to accurately measure the force between the assemblies. Such force may act up or downward, resulting from the weight of the CT string (tension) or action of high wellhead pressure (compression).

1.2.7 Stripper Mount The outer frame of the injector head is equipped with a stripper mount facility which secures the injector head to the pressure control stack. The stripper is generally permanently bolted in place. With the injector head outer frame fixed to the pressure control stack and the inner injector head assembly supporting the tubing string, some limited movement is allowed to ensure correct alignment and operation of the weight indicator load cell. In some larger models of injector head, the stripper is mounted on a subassembly which can be removed during transportation.

Tubing measurement and coating accessories Levelwind assembly

Reel drum

Figure 17. Typical CT reel configuration.

Page 14 of 33

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

2 COILED TUBING REEL 2.1 Description The primary function of the coiled tubing reel is to safely store and protect the CT string. This should be achieved while avoiding excessive damage to the string through fatigue (bending) or mechanical damage from spooling. In addition, the reel typically incorporates several features which, although less obvious, are equally important to the successful operation of the CTU. Most significant of which is the swivel facility which enables fluids to be pumped through the tubing string while the reel drum rotates.

Section 210 Rev A - 98

Almost all reels rely totally on hydraulic power to operate the drive, braking and spooling guide (levelwind) systems. Previous reel designs have used pneumatics, or a combination of pneumatics and hydraulic power, to control some of the brake and levelwind systems. The reel levelwind is frequently used as a mounting position for a variety of tubing protection, monitoring and measuring equipment. Figures 17 identifies the principal components of a typical CT reel.

Figure 18. Truck mounted reel (fixed).

Figure 19. Truck mounted reel (skid).

Figure 20. Skid mounted reel.

Figure 21. Special application reel.

Page 15 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

2.2 Features CT Reels are commonly available in a number of configurations and can be categorized as shown below. Local conditions and the nature of the CT operations will determine the type of reel required.

Schlum berger Dow ell

The evolution of CT string sizes and the general trend toward longer CT work strings has resulted in many different reel designs, many of which are still in common use. However, the facilities and components identified below are found on almost all reels: • Reel drum

• Truck mounted (fixed) - permanently fixed to the truck chassis (Figure 18)

• Reel drive and brake systems

• Truck mounted (skid) - may be changed out (Figure 19)

• Reel swivel and manifold

• Skid mounted - for offshore operations (Figure 20)

• Levelwind assembly

• Trailer mounted - for large capacity (length) or heavy weight strings

• Depth measurement accessories • Tubing lubrication equipment

• CT logging reel - fitted with electrical swivel/collector • Crash protection frame • Special application reel - typically for completion applications (Figure 21) With the advent of larger CT sizes, that are installed as completion tubulars, there is increased use of special reels and spooling stands designed to handle large tubulars. These structures typically enable the shipping spool to be fitted in place of the drum assembly, thereby avoiding unnecessary spooling, which in large tubing sizes can be difficult and hazardous.

Page 16 of 33

2.2.1 Reel Drum The reel drum assembly typically consists of a reel drum, axle, flanged connection on the axle to allow the swivel to be connected, and chain sprocket on the axle by which the drum is driven. A second chain sprocket on the axle is often used to drive the levelwind leadscrew. Direct drive reels have a motor and gearbox mounted directly on the axle. The reel axle bearings are mounted and secured on support posts which form part of the reel chassis.

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Freeboard A

Section 210 Rev A - 98

A facility to lock the reel drum while being transported is required on all reels. This is commonly achieved by securing with a chain and binder between the reel drum rim and a point on the reel chassis. This must be in addition to any hydraulic or pneumatic brake which is operated from the control cabin. Reels that have wireline installed require a modified axle to allow an electrical collector to be fitted to the axle. The theoretical tubing capacity (Figure 22) of any drum can be calculated using the procedure shown below. This method of calculation assumes perfect spooling across the width of the drum. Since in practice this is difficult to achieve, an allowance must be made to maintain the reel capacity within its practical limitations.

C

L = (A+C) (A) (B) (K) where: L = tubing capacity (ft) A = tubing stack height (in.) B = width between flanges (in.) C = reel drum core diameter (in.) K = K value for different tubing sizes.

B

Figure 22. Reel drum capacity.

Figure 23. Reel back tension.

Page 17 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

The K values for different tubing sizes are: Tubing OD (in.) 1 1-1/4 1-1/2 1-3/4 2 2-3/8 2-7/8 3-1/2

K value 0.262 0.168 0.116 0.086 0.066 0.046 0.032 0.021

The freeboard is the amount of clearance between the OD of the reel flanges and the OD of the wrapped tubing at maximum capacity (L). The minimum recommended freeboard varies with the tubing size: Tubing OD (in.) 1 and 1-1/4 1-1/2 and 1-3/4 2 >2

Freeboard (in.) 1.5 2.0 3.0 10.0

2.2.2 Reel Drive/Brake Systems All reels are hydraulically driven, although the control system and type of motor vary between manufacturers and reel models. Most reels can be powered in an “in-hole” and “out-hole” direction. However, during normal operations, only the out-hole option should be selected, since it is the action of the reel drive motor in this direction that provides the back tension applied to the CT string while running in and out of the well. The hydraulic pressure in the drive system can be varied to control the torque output of the motor which allows the tension on the tubing (between the injector head and reel) to be varied. Generally, only sufficient tension to keep the tubing straight between the reel and injector head should be applied (Figure 23). Applying excessive tension may result in premature failure of the hydraulic and drive components or damage to the tubing. This combined with incorrect spooling will almost certainly result in some tubing damage. The amount of hydraulic pressure required to achieve a satisfactory tension will depend on the amount of tubing contained on the reel and the distance from the injector

Figure 24. Typical reel manifold configuration.

Page 18 of 33

Schlum berger Dow ell

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

head. The distance from the reel axle to the top tubing wrap may be regarded as a lever through which the drive system torque must be transmitted to tension the tubing string. The greater the distance, the more torque will be required to maintain a constant tension. To increase the torque output of the drive system, the hydraulic pressure must be increased. Therefore, while pulling out of the well, the distance from the reel axle to the top wrap is increased, requiring that the hydraulic pressure in the drive system must be increased to keep a constant tubing tension. While running in the hole (RIH), the pressure required to maintain sufficient back tension will reduce as the number of wraps on the drum is reduced.

Section 210 Rev A - 98

rated within the motor assembly. This is set/released by a dedicated hydraulic circuit which is controlled from the control cabin. Generally, the reel brake is applied whenever the tubing is stationary. However, consideration must be given to the consequences of actions or operations which may affect the stability of the CT string in the injector head, e.g. if highdensity fluid is to be pumped through the CT at depth, the increase in weight may cause the CT to slip through the injector chains. With the reel brake applied, the resulting force/tension would then be applied to the reel. 2.2.3 Reel Swivel and Manifold

In addition to the torque changes with varying reel capacity, the change in weight will also affect the pressure required to drive the reel. This is particularly noticeable when starting from rest especially when the reel contains highdensity fluids or electric cable. The reel drive motor is either mounted on the base of the reel chassis, or mounted directly on the axle. If mounted on the reel chassis, it is connected by a chain and sprocket to the reel axle. Reel brake systems may be air or hydraulically operated. Most current models have a hydraulic reel brake incorpo-

The design and configuration of reel swivels and manifolds vary according to the manufacturer and model of the reel. Early models were of simple design and often contained threaded connections on the swivel or manifold. It is a requirement many organizations that all treating equipment be of integral or of non-pressure union construction. This restriction also prevents the use of Swagelok fittings to connect the tubing end within the reel core. Therefore, the CT string is typically terminated with a 1502 Weco union which has been welded in place and has undergone the required quality control procedures.

Figure 25. Reel levelwind assembly.

Page 19 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Schlum berger Dow ell

All reels should have a valve fitted as close as practical to the end of the CT string. This valve can be closed in the event of a swivel seal failure while the CT is being run, thereby isolating the contents of the string. Reels that have wireline installed require a modified manifold to enable wireline access (pressure bulkhead) downstream of the isolation valve. The reel fluid manifold is generally considered in two parts - the external manifold which consists of treating iron outboard of the swivel, and the internal manifold which is mounted within the reel core. 2.2.4 Levelwind Assembly Accurate and even spooling of the CT onto the reel drum is important for several reasons: • Badly spooled damage is liable to damaged at the contact points. Even apparently minor surface damage can affect tubing life or performance.

Figure 26. UTIM device mounted on CT reel levelwind.

• For the reel drum to achieve maximum capacity the CT must be properly spooled.

Figure 27. CTL reel configuration.

Page 20 of 33

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

• Poorly spooled tubing may shift and slacken on the reel while being transported. This may result in damage or problems when the tubing is drawn from the reel for the next operation. • Corrosion protection of the external surface is more effective if the tubing is closely and evenly spooled.

Section 210 Rev A - 98

which is used to transmit power and data between the BHA and surface equipment. The following items are required to complete the surface equipment hook-up associated with the CT reels to be used on coiled tubing logging operations: Pressure Bulkhead (PBH)

To help achieve a satisfactory spooling standard, the levelwind assembly guides the tubing onto the reel drum and automatically follows the progress of the spooling tubing. A manual override facility allows minor adjustments to be made to the position of the levelwind head when required. In addition, some vertical adjustment of the levelwind assembly is necessary to allow the fleet angle of tubing to suit the equipment rig-up. 2.2.5 Tubing Measurement Accessories The levelwind travelling head provides an ideal mounting position for friction wheel depth counters or encoders. Back-up mechanical counters that display large-sized digits can, in most cases, be read from the operator’s console. The travelling head also provides the mounting position for tubing monitoring equipment such as the Dowell Universal Tubing Integrity Monitor (UTIM) device. 2.2.6 Tubing Lubrication Equipment Current reel designs include a fixed tubing lubrication/ inhibition system, part of which is permanently mounted on the reel chassis, with the control system located on the operator’s console. 2.2.7 Crash Protection Frame The degree of protection required depends on anticipated application and use of the CTU (e.g. offshore skid-mounted or truck-mounted reel). In addition to the practical efficiency of the crash frame, consideration must be given to the requirements of certifying or regulatory authorities. For example, a DNV certified unit for offshore use must have a fitted reel roof, coated with a non-slip material, to assist the seamen in attaching the load to the crane hook.

The pressure bulkhead is used to allow electrical connection of the reel mounted electrical components to the logging cable inside the CT string. This must be achieved while maintaining the pressure integrity of the reel manifold. Reel Collector The reel connector is used to allow an electrical connection to be made between the cable in the rotating reel core and the surface electrical equipment. 3 CT POWER PACK 3.1 Description The function of the power pack may be simply stated as providing the hydraulic power to operate the coiled tubing unit (CTU) and pressure control equipment, e.g., BOP system. To perform this function satisfactorily under varied conditions and for the duration of any coiled tubing (CT) operation, current generation power packs are designed to operate independently of exterior power or air supplies once started. In addition to the hydraulic power supplied when running, the power pack incorporates an accumulator facility to allow limited operation of pressure control equipment following engine shutdown. A compressor mounted on the engine provides an air supply for operation of the engine controls and pneumatic systems on the CTU, e.g., the stripper air-operated pump, injector-head chain lubrication, lights and transfer pumps. The power-pack air receiver will provide sufficient storage to allow an engine restart shortly after shutdown, provided the unit pneumatic systems are isolated.

2.2.8 Wireline Reels Wireline reels are used in CT logging operations and incorporate a logging cable installed inside the CT string

The environment in which the CTU is to operate will determine the engine protection facilities required by the relevant local and national authorities. For example, off-

Page 21 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Lay er 1 TemhpCoola Hig eratu re nt

High Exhau st Tem pe ratu re

Low Oil Pre ssure

Schlum berger Dow ell

Lo ss of C oola nt

Oil Pr essu re

Coo lant Te mper atur e

En gine Tach omet er

Per missive star t

St art Eng ine Kill

Em ergen cy Kill

Air Pr essur e

Figure 28. CT power pack. shore skid units operating in the North Sea are required to be fitted with an engine (and electrical, where fitted) protection package that allows the unit to be operated in Zone II areas, hence the designation of Zone II unit. The CTU configuration will determine the location of the power pack and corresponding control equipment.

continuing satisfactory operation of all CTU functions. The importance of the relevant power-pack checks being thoroughly and regularly completed is obvious. In addition the completion of the required reports will provide a useful record of the power unit performance, identifying possible problems before the operation of the CTU is affected. 3.2 Features

• Truck or trailer mounted using the truck engine as a power source. • Truck or trailer mounted with an independent power source. • Skid mounted with the control cab and power pack incorporated on one skid, designated a three-piece unit, i.e., control cab/power pack, reel and injector-head/BOP transport basket.

The majority of CTUs in use are assembled by Hydra-Rig. The evolution of CTU design to the current standards has resulted in several different designs of the power pack being supplied. Figure 28 shows the power pack/control cab skid from a three-piece Hydra-Rig CTU. In general, all power packs will include the following major components: • Engine

• Skid mounted with the control cab mounted separately from the power pack, designated as a four piece unit.

• Hydraulic pumps

Regardless of the type of unit to which the power pack is fitted, the function and facilities contained within the power pack will be similar.

• Pressure Control Valves

Successful operation of the CTU requires the delivery of precisely controlled hydraulic power on demand. Maintenance checks performed on the CTU, such as those identified in the CT STEM program, are designed to ensure

• Filters and Strainers

Page 22 of 33

• Hydraulic Reservoir

• Hydraulic Fluid

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Section 210 Rev A - 98

• Heat Exchanger and Thermostatic Valve

Engine instrumentation will generally include the following.

• Accumulator

• Oil Pressure Gauge

Operation, or even start-up of the CTU power pack, must not be attempted until a series of maintenance and operational checks has been completed. Failure to follow the prestart-up procedure may expose equipment and personnel to unacceptable risks.

• Coolant Temperature Gauge

The prestart-up operational checks will vary with the location and application of the CTU but should include the following points as a minimum requirement.

3.2.2 Hazardous Area Designation

• Ensure any location requirements, such as a permit to work systems, are complied with fully and that actions need for such requirements have been completed, e.g., positioning of gas detecting and fire-fighting equipment. • Ensure operating and associated personnel are aware of the above requirements, and that only qualified personnel are authorized to operate the equipment. 3.2.1 Power-Pack Engine

• Air Pressure Gauge • Ammeter (where applicable)

Engines and electrical equipment are often required to be specially protected or isolated before their use is permitted in certain environments. The identification of designated hazardous areas or zones in and around wellhead and process plant areas is the principal basis upon which equipment suitability is assessed. The extent of the zoned area is generally determined by the relevant national authorities. Consequently, international variations exist both in terminology of areas and in the extent to which they apply; however, zoned areas will generally be based on relevant API guidelines.

Almost all engines fitted to CTU power packs are of the General Motors Detroit series. They may be of 8V, 6V or (more recently), six cylinder, in-line configuration. Coiled tubing units manufactured after 1990 are likely to be fitted with Caterpillar engines. This is primarily due to the superior engine noise and emission control specifications achieved by the Caterpillar engine.

The inspection and certification of equipment as being in compliance with the operator’s standards are often conducted by third-party inspection companies. Examples are Det Norske Veritas (DNV) and the American Bureau of Shipping (ABS).

Engine controls are likely to be remotely operated from the control console and from the engine control panel located on the power pack. Some three-piece units may only be equipped for single-station operation, i.e., all engine controls are located on the operator’s console.

Diesel engine driven equipment that is intended for use within Zone II areas and which is in compliance with the most rigorous standards set by operating companies will typically be fitted with the following engine protection equipment.

The following engine controls are found on standard engine sets.

• Air-inlet shutoff valve - designed to shut down the engine when an overspeed condition is detected by increased airflow through the shutdown valve or by the overspeed governor, where fitted.

• Engine Start • Engine Stop

3.2.3 Zone II Engine Protection Equipment

• Emergency Kill

• Liquid-cooled exhaust gas manifold/heat exchanger. Designed to maintain engine surface temperatures below 392°F (200°C)

• Engine Throttle

• Exhaust gas spark arrestor and flame trap

Page 23 of 33

Section 210

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Rev A - 98

Open loop:

Return flow to reservoir

Schlum berger Dow ell

Directional, pressure and Load holding flow control (counterbalance) valves valves Injector head drive motors

Fixed displacement pump

Closed loop:

Directional control valves

Crossover relief valve Injector head drive motors

Variable displacement pump

Figure 29. Open and closed loop hydraulic systems. • Engine breather and air-box breather flame traps • Screw-secured oil-filler cap and dipstick • Heavy-duty radiator • Plastic blade fan The protection package will initiate engine shutdown in two ways. • In the case of engine overspeed, by closing the air-inlet shutoff valve. • In the case of high exhaust temperature, high water temperature and low engine oil pressure, by cutting off the fuel supply, generally by an actuator moving the engine fuel rack.

Balanced vane-type hydraulic pumps for this application are commonly supplied by Abex Denison. Most of the models used are high-performance double pumps, thereby allowing two separate hydraulic systems to be run from one pump assembly. In this case, the pump contains two separate pump cartridges supplied by a common suction line but having separate discharge ports. The construction of the pump body allows cartridges of a different size, and therefore output, to be fitted. Consequently, the output capability of the hydraulic pump array is tailor made to the requirement of the system it supplies. 3.2.5 Pressure Control Valves Each hydraulic circuit must be fitted with a device to control the maximum pressure within the system. On Hydra-Rig CTU hydraulic circuits, this is achieved in several ways. • Preset relief valves

3.2.4 Hydraulic Pumps • Pilot-operated relief valves The hydraulic pump array will vary with the model and manufacturer of the CTU. The hydraulic systems on most CTUs consist of balanced vane type pumps operating in an open-loop system (Figure 29).

Page 24 of 33

• Unloader valves

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Section 210 Rev A - 98

Preset Relief Valves

3.2.7 Filters and Strainers

This type of valve is manually adjusted and set to the maximum desired pressure in the system. Once this pressure is reached, the relief valve lifts allowing excess flow to be directed back to the hydraulic reservoir. This action imparts considerable energy to the hydraulic fluid, causing the system temperature to rise if the valve relieves over a prolonged period.

The hydraulic fluid and system are kept clean by passing the fluid through filters and strainers as it flows through the circuits. A strainer is a coarse filter, commonly made from wire mesh, which is generally fitted to the suction line inside the reservoir. The strainer is generally specified by a mesh number or standard sieve number.

Pilot-Operated Relief Valves Pilot operated relief valves are similar to preset relief valves, but have the additional facility of allowing the relief pressure to be remotely controlled by a pilot control valve connected to the relief valve by a pilot control line. The pressure may be remotely varied up to the preset maximum setting of the relief valve.

Unloader Valve Unloader valves are similar to relief valves, but differ in that when the preset maximum pressure is reached, the valve reacts to isolate the system and direct the flow to the reservoir under no load. When the system pressure is reduced, the valve opens to recharge the system, closing again when the desired pressure is reached. Unloader valves are commonly fitted to systems that require little flow during operation and that are also fitted with accumulators. Hydraulic circuits that supply BOP operating pressure are generally fitted with an unloader-type valve. 3.2.6 Hydraulic Fluid Reservoir The hydraulic fluid reservoir performs several functions.

Filters retain much smaller particle sizes than strainers and are commonly located on the reservoir return lines. Filters are generally specified by a micron number and as being either nominal or absolute. A nominal filter rated at 10 micron will trap most of the particles of that size; however, an absolute filter will trap all particles of that size and greater. In addition to the filters placed in the reservoir return lines, some circuits have an in-line filter installed upstream of the valve gear, particularly where there is a limited flow through the system, e.g., on the priority supply line to the Monsun Tison valve, the main control valve of the injector head. Many filter assemblies incorporate a filter condition indicator. This simply gives some indication of the differential pressure being applied across the filter. A filter which is partially plugged will create a larger differential, the indication of which is commonly displayed by a colored indicator system. A green display during operation is normal; a red display indicates the filter requires changing. In addition to this feature, or as an alternative, a bypass system may also be incorporated into the filter assembly. This allows fluid to bypass the filter should the back pressure caused by a blocked, or partially blocked filter, become too severe.

• Stores the hydraulic fluid 3.2.8 Hydraulic Fluid • Allows the fluid to cool The hydraulic fluid has four main functions • Allows settling of dirt and metal particles • Allows entrained air to be released. The reservoir is generally mounted high in the power pack to provide a positive head of pressure at the hydraulic pump suction port. Suction lines from the reservoir to the pumps are commonly fitted with strainers and isolation valves.

• Power Transmission - to transmit power efficiently, the fluid must flow easily through lines and components. Resistance to flow caused by friction will result in power loss. The fluid should also be as incompressible as possible to transmit power immediately on start-up. • Lubrication - most hydraulic components are lubricated by the fluid; therefore, for a long component life, the fluid

Page 25 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

should contain the necessary additives to ensure high antiwear characteristics. • Sealing - in many cases, the close mechanical fit and hydraulic fluid provide the only seal against leakage within the hydraulic component. Therefore, the mechanical fit and fluid viscosity will determine the leakage rate.

Schlum berger Dow ell

Accumulators fitted to the power pack generally contain an internal bladder which is precharged with nitrogen. The precharge pressure is dependent on the application and volume of the accumulator. For example, the BOP circuit is fitted with a large-capacity accumulator which, when fully charged, will allow limited operation of the BOP following shutdown of the power pack.

• Cooling - heat generated by the components in the system is dissipated by the fluid as it passes through the lines and reservoir.

4 CONTROL CABIN

In addition to the four main functions of the fluid, a number of other quality requirements are desirable.

The control cabin contains all of the controls and instruments necessary to allow the CT operation to be run from one control station. The location of the control cabin will vary depending on the configuration and type of the coiled tubing unit; however, the cabin is generally situated behind the CT reel, in line with the wellhead/injector head. To help achieve maximum visibility from the control station, the cabin is commonly elevated.

• Prevent rust, corrosion or pitting. • Prevent sludge formation. • Depress foaming. • Maintain stability over a wide temperature range. • Separate out water. • Be compatible with seal and gasket materials. The excess generation of heat and associated problems is a relatively common problem in incorrectly designed or operated hydraulic systems. To combat this potential problem and to assist with heat dissipation during periods of high load or high ambient temperature, most CTUs are equipped with a heat exchanger. Heat exchangers may rely on air or water to cool the fluid, and are generally located on a main reservoir return line. This ensures that the majority of the fluid passing through the system goes through the heat exchanger. 3.2.9 Accumulator

4.1 Description

The level of control and instrumentation fitted will greatly depend on the model and version of the CTU. However, typical design objectives include ability to: • Control and monitor the operation of all of the CTU operating functions. • Control and monitor the operation of well pressure control equipment. • Monitor and record the principal well and CT string parameters of wellhead pressure, circulating pressure, tubing weight at the injector head and tubing depth. The principal benefit of this comprehensive control and instrument package is that it provides the operator with an increased awareness of the CTU operating conditions. This in turn provides three important prerequisites that are crucial to achieving adequate service quality:

Hydraulic systems that operate at a static pressure and have a low fluid flow rate are commonly fitted with accumulators. In this application, the accumulator performs two functions.

• The CTU can be operated safely and efficiently.

• Energy storage (e.g., BOP accumulator)

• An accurate CT string work record is developed, based on the primary factors which influence the useful life of the tubing.

• Shock absorption (e.g., tensioner circuit accumulator).

Page 26 of 33

• Potential problems can be identified and rectified before they interfere with the operation of the CTU.

INJECTOR OUTSIDE TENSION PRESSURE 150 PSI MAX

CLOSE OPEN

CLOSE

OPEN

INSIDE TRACTION PRESSURE DRAIN

INJECTOR INSIDE TRACTION PRESSURE 1500 PSI MAX

B O P

Rev A - 98

EMERGENCY TRACTION SUPPLY

BLIND RAM

SHEAR RAM CLOSE OPEN

SLIP RAM

Section 210

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Schlum berger Dowell

AIP SUPPLY PRESSURE

CLOSE OPEN

ENGINE STOP OFF

CLOSE OPEN PRESSURE

BLEED

ON

TOP ON

OFF

TUBING WEIGHT INDICATOR

30 GPM PUMP

60 GPM PUMP

PRESSURE OFF

OFF CIRCULATING PRESSURE

ON

BOP SUPPLY

REEL BRAKE INSIDE TRACTION SUPPLY PRESSURE

AIR HORN

BOP SUPPLY PRESSURE MIDDLE

STRIPPER #2

THROTTLE

WELLHEAD PRESSURE

OFF

BOP PRESSURE

ON

STRIPPER #1

INSIDE TRACTION

PRIORITY PRESSURE 2,000 PSI MAX

PRESSURE OFF

Schlumberger Dowell

INJECTOR DIRECTIONAL CONTROL VALVE PILOT PRESSURE

REEL PRESSURE

PRESSURE ADJUST IN

RETRACT

NEUTRAL

PACK

RETRACT

NEUTRAL

INJECTOR CHAIN LUBRICATION

PACK HIGH

UP BOTTOM

STRIPPER SYSTEM PRESSURE 5000 PSI MAX #2 STRIPPER

EMERGENCY STOP

ON

PIPE RAM

ON

#1 STRIPPER

PRESSURE OFF

INJECTOR SPEED

LEVELWIND ARM

LOW

DOWN

OUT

INJECTOR MOTOR PRESSURE

INJECTOR MOTOR PRESSURE ADJUST

REEL PRESSURE ADJUST

INJECTOR CONTROL

LEVELWIND OVERRIDE

STRIPPER PRESSURE ADJUST AIR REG. CONTROL

REEL TUBING LUBRICATION

REEL CONTROL

Figure 30. Typical control panel layout - flat panel.

CLOSE

BOP PRESSURE

STRIPPER #1 PRESSURE

BOP SYSTEM PRESSURE

STRIPPER #2 PRESSURE

STRIPPER SYSTEM PRESSURE

OPEN

INSIDE TRACTION PRESSURE DRAIN

STRIPPER SYSTEM PRESSURE

SYSTEM AIR PRESSURE

TUBING WEIGHT INDICATOR STRIPPER BLEED

PRESSURE

BLEED

OUTSIDE TENSION INJECTOR

NEUTRAL

SHEAR RAM

BLIND RAM

CLOSE OPEN

CLOSE OPEN

RETRACT

SLIP RAM CLOSE OPEN

PIPE RAM

ON

ON

CLOSE OPEN

CHARGE PRESSURE

PRIORITY PRESSURE

DEPTH SYSTEM WELLHEAD PRESSURE

EMERGENCY TRACTION SUPPLY

PACK STRIPPER #1

B O P

INSIDE TRACTION SUPPLY PRESSURE

OFF

INSIDE TRACTION

PRESSURE ADJUST

INJECTOR LUBE HIGH

INJECTOR CONTROL

OFF TOP TRACTION

IN

INJECTOR TOP TRACTION CYL.

LOW

INJECTOR 2 SPEED

REEL LUBE ON

OFF

ENGINE STOP

REEL BRAKE REEL BRAKE PRESSURE

NEUTRAL RETRACT

AUX BOP CLOSE OPEN

BOP SUPPLY ON

PACK

ON

OFF MIDDLE TRACTION

STRIPPER #2

CIRCULATING PRESSURE

OUT INJECTOR MIDDLE TRACTION CYL.

INJECTOR PRESSURE ADJUST

Schlumberger Dowell

REEL PRESSURE ADJUST

OFF

INJECTOR SLOW SPEED CONTROL ON STRIPPER PRESSURE ADJUST

EMERGENCY STOP

THROTTLE

OFF BOTTOM TRACTION INJECTOR BOTTOM TRACTION CYL.

INJECTOR CONTROL PILOT PRESSURE

INJECTOR MOTOR PRESSURE

REEL PRESSURE

LEVELWIND LEVELWIND OVERRIDE ARM

REEL CONTROL AIR HORN

Figure 31. Typical control panel layout - split panel.

Page 27 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Schlum berger Dow ell

4.2 Features

Inside Traction Pressure Adjust

Controls and instruments can be grouped by function as follows.

This is a pressure reducing valve used to adjust the hydraulic pressure to the cylinders (increase and decrease pressure). The hydraulic supply is from the priority circuit (2,000 psi); the maximum chain tension pressure should not exceed 1,500 psi.

• Injector chain inside tension • Injector chain outside tension

Inside Traction Supply Pressure Gauge • Injector-head drive • Reel · • Lubrication controls • Power unit • BOP · • Stripper · • Principal gauges · • Emergency hydraulic supply equipment · • Electronic equipment The illustrations in Figure 30 and Figure 31 show typical console layouts. The explanations given below summarize the function of each control or instrument group.

Displays system pressure as determined by the pressure adjust valve.

Control Valve (3) May be used to isolate each of the three inside chain tension cylinder sets.

Pressure Gauges (3) Displays the hydraulic pressure downstream of the control valves.

Inside Traction Pressure Drain This valve is used to bleed pressure from the system when the control valves are open. Caution must be exercised when opening this valve when tubing is suspended in the injector chains because a sudden drop in the cylinder pressure will result. Fine pressure adjustment should be made by the pressure adjust valve. 4.2.2 Injector Outside Chain Tension

4.2.1 Injector Inside Chain Tension This system is served by the following controls and instruments.

This system is served by the following controls and instruments.

Injector Outside Tension Pressure Gauge Emergency Traction Supply A three-way valve that is used to apply full priority pressure in the event of an emergency (runaway) situation. In the normal operating position, the pressure to each of the three tensioner cylinder ram sets is determined by the pressure adjust valve.

Page 28 of 33

Displays the current hydraulic pressure within the outside tension cylinders.

Pressure Valve A needle valve which isolates the supply pressure from the system.

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Section 210 Rev A - 98

Bleed Valve

4.2.4 Reel Controls

A needle valve used to bleed pressure from the system.

This system is served by the following controls and instruments.

4.2.3 Injector-Head Drive

Reel Control This system is served by the following controls and instruments.

The reel directional control valve. Should be locked in the out-hole direction for all normal operations.

Injector Motor Pressure Adjust Valve Reel Pressure Adjust A remote pilot valve used to control the injector drive pressure.

A remote pilot valve used to adjust the reel drive system relief valve from zero to the preset maximum.

Injector Control Pilot Pressure Gauge Reel Pressure Gauge Displays the pilot control pressure, which is equal to the discharge pressure of the Husco valve.

Displays the hydraulic pressure to the reel motor.

Injector Control Valve

Reel Brake

Provides directional and speed control of the injector- head motors by controlling the output of the Husco valve. Pulling the valve handle backward selects the out-hole direction; pushing the handle forward selects an in-hole direction.

A valve used to apply/release the reel brake.

Levelwind Override

Injector Speed High/Low

Advances or retards the position of the levelwind traveling head.

Valve used to control injector-head motor speed selection.

Levelwind Raise/Lower

Injector Motor Pressure

Control to raise or lower the levelwind assembly.

Displays the injector motor hydraulic pressure.

4.2.5 Lubrication Controls

30-GPM Pump/60-GPM Pump

This system is served by the following controls and instruments.

These two valves are used to control the injector-head motor speed. One or more of the pumps must be selected in order to operate the injector head. For high injector head speeds both pumps may be selected.

Reel Tubing Lubrication A pilot valve used to control (on/off) the reel tubing lubrication system.

Priority Pressure Gauge Injector Chain Lubrication Displays the priority system pressure. The priority system pressure is used to operate several of the remote pilot functions associated with the other controls.

A pilot valve used to control (on/off) the injector-head chain lubrication system.

Page 29 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Schlum berger Dow ell

4.2.6 Engine Controls

4.2.8 Strippers

This system is served by the following controls and instruments.

This system is served by the following controls and instruments.

Emergency Stop

Stripper Selection Valve

A valve which operates the engine’s air inlet shutoff valve. Should only be used in an emergency. The shutoff valve must be manually reset at the power pack to allow further operation.

Three-way valve which directs the hydraulic supply to the appropriate stripper.

Engine Stop

Displays the discharge pressure of the stripper supply pump.

A valve which remotely shuts off the diesel fuel supply to the engine.

Throttle

Stripper-System Pressure Gauge

Stripper Pressure Adjust

Used to control the engine speed.

Air regulator control which controls the operation of the stripper supply pump. Stripper pressure decrease cannot be achieved by this control.

Air-Supply Pressure Gauge

Retract/Neutral/Pack Valve (2)

Displays the pneumatic system pressure.

Control valve for each stripper selecting the desired function. The neutral position bleeds stripper pressure.

4.2.7 Blowout Preventers (BOP)

Stripper Pressure Gauge (2) This system is served by the following controls and instruments.

Displays the hydraulic pressure of the selected function, as selected by the retract/neutral/retract valve.

BOP-Supply Pressure Gauge 4.2.9 Principal Gauges Displays the BOP’s hydraulic supply pressure.

Wellhead Pressure Gauge BOP Pressure Displays the hydraulic pressure in the BOP circuit downstream of the BOP supply valve.

Displays wellhead pressure at the BOP pressure port, generally located at the center of the BOP stack.

Circulating Pressure Gauge BOP Supply Valve Displays pressure at the reel-manifold pressure sensor. Valve used to isolate the BOP circuit from the hydraulic supply.

Ram Control Valve (4) Used to open/close each of the four ram sets (blind, shear, slip and pipe rams).

Page 30 of 33

Weight Indicator Displays the weight exerted by the tubing on the injector head.

Schlum berger Dowell

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

4.2.10 Emergency Hydraulic Supply The emergency pump console contains the pressure gauge and valves to allow the selection and monitoring of emergency hydraulic supply to the stripper, BOP and chain tensioner systems, as selected. Control of pressure is then by manual effort. 4.2.11 Electronic Equipment The following electronic equipment may be fitted or installed to monitor and record the CTU, tubing, and well data. • Electronic Depth Sensors • Electronic Pressure Sensors • Tubing Monitoring Equipment 4.3 Operating Technique The controls and systems of any CTU must be operated in a manner which ensures that the following general requirements are met: • The safety of personnel associated with the operation and maintenance of the CTU and ancillary equipment must not be jeopardized by the actions of the CT operator. • Operation or maintenance of any controls or system of the CTU must not compromise the efficiency of the well control barriers. The operation of primary, secondary and tertiary (where required) well control barriers must be understood. In addition, the consequences of their operation must be understood. • The operating limits of key components and systems associated with the CTU or ancillary equipment should not be exceeded. • The operating limits defined by appropriate CT software models should not be exceeded. In the event that this information is not available, the operation should be conducted within the operating limits identified during the job design phase. • Applicable safety and environmental policies must be understood and complied with.

Section 210 Rev A - 98

The equipment operator should coordinate the control and instrumentation functions to affect a high level of control over the CTU. Good control, together with smooth operation will help to improve the reliability and longevity of the components, system controls, tools and tubing used. During operation, consideration must be given to the speed and levels of force applied to the CT. These must be consistent with the well conditions and equipment limitations.

Starting/Stopping The process of starting and stopping the movement of the CT must be conducted by applying or reducing the driving force slowly and smoothly. Sudden changes may exert unacceptably high forces to the tubing, reel, injector head, power pack and pressure control equipment components. NOTE: If any of the defined operating limits are met, or exceeded, the injector-head drive must be disengaged as quickly as possible. Operation may commence only when the appropriate course of action has been determined. Changes in the injector head direction must only be attempted after the tubing has been brought to a complete halt. Several precautions must be taken when the injector-head drive is to be engaged. These may include, but not be limited to: • Check that the BOP rams and wellhead valves are open (including the subsurface safety valve, where applicable). Ensure that all pressure control systems are appropriately energized. • Ensure that parking devices such as BOP slips, reel brakes, etc., are released and that the appropriate reel back tension is applied. • Note (reset if applicable) the depth system readout. • The weight indicator reading at the maximum allowable tension (Tmax), as determined during the job planning phase, must be known and noted by the operator prior to commencing the operation.

Page 31 of 33

Section 210 Rev A - 98

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Running the CT The location of the CT BHA in relation to the wellbore tubulars and restrictions should be a constant consideration. Appropriate precautions must be taken as the CT BHA passes restrictions or variations in the wellbore diameter. These may include, but not be limited to, the following.

Schlum berger Dow ell

The control and operation of the CTU should be consistent with any conditions, known or suspected, which may affect the CT operation. The following instruments and gauges are generally variable throughout a CT operation and are assigned an “A” priority. • Weight indicator display

• Close observation of the weight indicator display. • Wellhead pressure gauge • A reduction in the running speed. • Coordination with operators of a specialist tool string, e.g., CT Logging company.

• Circulating pressure gauge In addition, the following locations are assigned an “A” priority.

• Checking the actual vs predicted weight/depth plots.

• Injector head and wellhead area

• The operator must, at all times, be prepared to quickly disengage the injector-head drive should abnormal conditions be observed.

• CT reel The following instruments and gauges are generally less likely to change rapidly and are assigned a “B” priority.

Pressure Control Equipment • Depth measurement system With the exception of strippers and equipment designed to be operated while the tubing is in motion, operation of pressure control equipment must only be attempted when the tubing is stationary. The operation of BOP functions which may damage the CT, e.g., the blind rams or shear rams, must only be attempted after considering the implications of such action. Lockout devices should be fitted to all BOP controls that may initiate severe damage to the CT if unintentionally actuated.

• Stripper pack pressure • Inside chain tensioner system In addition, the following locations are assigned a “B” priority. • Pump and choke parameters • Auxiliary equipment

4.4 Instrument Scanning To ensure that unusual circumstances during a CT operation are detected as early as possible, it is necessary for the operator to constantly scan the CTU instrument array.

The following instruments are generally static throughout the operation. They do not normally require adjustment and are assigned a "C" priority. • Power-Pack Engine Gauges

The priorities assigned to each instrument group are intended to initiate a regular scanning sequence which should become habitual to the operator during normal operations. However, during special or emergency operations, some instrument groups may require extra attention.

• Priority Circuit Pressure Gauge • BOP Circuit Pressure Gauge • Stripper System Supply Pressure Gauge • Injector Motor Pressure and Direction Pressure Gauges

Page 32 of 33

Schlum berger Dowell

Section 210

COILED TUBING SERVICES MANUAL COILED TUBING UNIT

Rev A - 98

• Outside Chain Tension Pressure Gauge

5 CTU COMPONENTS - APPOROXIMATE SIZES

• Inside Chain Tension Supply Pressure Gauge

Figure 32 shows approximate sizes for the following CTU components:

• Reel Back Tension Pressure Gauge • Injector head The frequency of scanning should ensure that all of the systems and locations are checked every four to five minutes.

• Reel • Control cabin

The B priority items should be checked every two to three minutes.

• Power pack.

Attention should be maintained on the A priority items at all times other than when B and C items are being checked.

Width (ft)

Length (ft)

Height (ft)

Weight (tons)

Injector Head

4

4

10

7

Reel (Small)

8

8

10

20-30

Reel (Large)

9-10

9-10

12

40-50

Control Cabin

8

8

8

7

Power Pack

8

12

8

12

Control Cabin/Power Pack Combined

8

16

8

16

Figure 32. Approximate sizes of CTU components.

Page 33 of 33