The following installation considerations apply to all threaded connections if mishaps are to be avoided:

• drift check and inspect connections before running;
• properly apply correct thread dope;
• backout and re-inspect connections that are stabbed in misaligned position;
• avoid high makeup speeds and use correct torque;
• use pup joint, couplings and cross-overs of the same tubular material, especially in CRA applications;
• additional makeup turns increase 8-round connection leak resistance in tension;
• additional torque reduces tendency of tubing to back-off when running Progressive Cavity Pumps (PCPs), etc. but do not exceed the maximum manufacturers recommended torque.

To ensure that the tubulars are run efficiently to the correct depth and in the desired condition, use of the following equipment and techniques should be considered in the design phase:

1 Hoisting capacity

The designer should be aware of the hoist capacity of the rig/hoist/snubbing unit which is to drill/workover the well. Where deep, heavy strings are required, it may be necessary to taper the string. Alternatively, the drilling/workover sequence may be re-arranged to allow the use of a larger rig for a particular well.

2 Handling

Handling of tubulars between the pipe deck and drillfloor should be carried out in accordance with EP-95000. Many Opcos have developed their own tubular handling and running manuals. Additionally rigs may now incorporate automated tubular handelling devices, such as the Verco International Pipemite.

Particular care should be taken when handling assemblies with pup joints, to ensure that the lifting point is above the centre of gravity. This ensures that the load is stable when lifted.

FRP tubulars are easily handled, but prone to damage, especially in cold climates, because they are light weight and very flexible. This type of pipe should be well supported during handling and should not be allowed to deflect to the point that composite material is over stressed and damaged.

3 Single joint weight compensator

Positioning of the pin in the box during make-up is critical. If no weight is transferred to the box, make-up cannot take place. If too much weight is transferred, stabbing and alignment becomes difficult and galling may occur due to high contact loads. It is extremely difficult to achieve accurate weight transfer with the standard rig hoisting system. The same problems also apply to connection break-out.

Although the susceptibility of connections to stabbing damage and galling can be minimised in the connection design process, controlled and accurate weight transfer is the key to successful make-up.

By the installation of a compensating device between the rig's travelling block and the single joint elevator, the weight of the pipe is neutralised and controlled downward penetration of the pipe is possible during make-up. This is highly recommended for both make-up and break-out of premium connections and/or corrosion resistant alloy (CRA) tubulars.

Service companies can supply single joint compensators in different weight ranges to cover all tubular sizes.

4 Drifting

Drifting should be performed on the pipe rack using a 42" (107 cm) long API non-metalic drift. Drifting from box to pin end, compressed (rig) air will blow the drift through the pipe in the horizontal position. It is not good practice to drift the pipe when secured in the rig V-door.

Additionally it is recommended that on completion of running the tubing, prior to running a wireline plug for pressure testing (if planned), a wireline drift using a gauge cutter should be made:

·tubulars 2 7/8" OD, drift diameter = tubing ID less 3/32";

·tubulars 3 1/2" OD, drift diameter = tubing ID less 1/8".

5 Stabbing

Stabbing guides are available to protect the threads and seals from standing up on the shoulder of the box end. The tubing joint needs to be held vertically over the stabbing guide and lowered in a controlled manner to maintain the alignment and guide the pin end into the thread engagement of the box.

• ·the pipe should not be rocked;
• ·pipe should be rotated with a strap wrench to initially engage threads.

6 Multi-size rig tongs

Automatic rig tongs are available, such as the Weatherford Torque Wrenching Machine, which can make up and break out drill pipe, drill collars, casing and tubing in one machine. The size range is 2 3/8in (0.0603 m) to 21 in (0.5334 m), and torques of up to 140,000 ft.lbs (189,805 Nm) are possible. Associated computer equipment monitors and records each make-up, ref. Section 3.4.8.

Specialist hydraulic power tongs with an integral back up tong should be used; pipe wrenches and standard rig tongs are not recommended.

7 Non-marking jaws

In corrosive operating environments where defects or stress concentrations in the tubular may have catastrophic consequences, the use of non-marking jaws should be considered, not only on the rig floor (tongs, slips, elevators) but also in the threading plant.

Such jaws, based on elastomers, are available from Weatherford and other service companies.

Frank's International and Weatherford can supply power tongs which grip the entire circumference of the pipe by means of fluid pressure applied to a non-metallic gripping surface. As a result, the tubular surface is not penetrated, and stress concentrations are avoided.

Conventional spiders/elevators are another potential problem with CRA tubulars. These are fitted with slip bodies and die inserts which penetrate the pipe surface when the system is activated, as illustrated in Fig. 2369. The force with which the dies are pressed against the pipe surface is increased by the weight of the string being held by the spider or elevator, due to a wedging action.

New systems, such as the Weatherford Micro-Grip system are equipped with thousands of fine teath formed into gripping bars which are imbedded in a carrier bound by an elastomer material that compresses with a radial force. The load is therefore distributed equally onto a large number of small peaks.

Care should be taken to check the tubing after make up for marking on the tubing by the tongs or slips. Should excessive marking be experienced it may be necessary to replace the tubing joint and change out the dies in the equipment.

8 Connection make-up torque

Proper torque values must be applied to obtain an optimum distribution throughout each thread connection and to ensure a pressure tight seal. Make-up to below the recommended minimum torque can result in leaks and/or joint failure/backoff.

Over-torquing may damage the threads or seals and may result in crimping the pipe inwards or belling outwards depending on the seal type.

The make-up torque for a connection should be recommended by the thread manufacturer, the value of which is dependant on the connection type, grade of material, size and weight of tubing.

It should also be noted that make-up torque will vary with different thread compounds and may also vary for different manufacturing batches of the same compound.

The correct make-up of any threaded connection cannot, however, be judged on torque alone. Correct make-up torque can be reached under a variety of unacceptable circumstances such as crossed, dirty, or galled threads. Surface finish variations may also influence the required torque. It is important that adequate pin penetration into the box is achieved to assure design stress levels are achieved in the connection. As a result, torque-turn data are published by the connection manufacturers and can be compared with that measured in the field using portable equipment (e.g. Weatherford JAM system). Torque-time plots are not suitable as they only show how the tong operates. This data is usually based on the use of an API 5A2 formulated compound. The use of a thread compound other than this requires the use of a correction factor (refer to Section 3.3.5.2) to accommodate the differences in friction coefficient. Critical on-site analysis of torque-turn graphs is, at present, seen as the best practical means of identifying potentially leaking connections before they are run into the hole (refer to connection leak testing, Section 3.4.9).

Even with premium seal connections incorporating a torque shoulder, in which final torque is a reasonable indicator of adequate seal pressure, torque-turn measuring equipment is recommended because of the accuracy of the torque gauge.

Soft-torque tongs (from Camco/Bilco or Frank's International) and/or Weatherford's A-Q-Tork system are recommended to prevent overtorque due to the inertia of the rotating pipe/tong mass.

High make-up speeds can cause damage due to a greater tendency to over torque, which produces thread and shoulder damage. It is recommended that 25 rpm or less is applied, especially just prior to final torque. (For CRA tubulars a make-up speed of 15 rpm is recommended).

Most FRP downhole tubulars use 8-round long thread connections and teflon based thread compounds. The make up torque is significantly lower than for steel tubulars and the make up is often performed with strap wrenches. However, without torque control, the potential exists for leaking connections and parted strings. It is particularly important to use the torque values provided by the manufacturer.

9 Connection leak testing

The requirement for leak testing while running or after the tubing has been landed depends on the type of completion, production conditions, location, etc. During the running of tubing two methods are used:

·External testing: This is achieved by setting two packing elements around the pipe above and below the connection, as illustrated in Figure 3.8. Leakage is detected by a drop in pressure of the water pumped into the void between the seals.

·Internal testing: This method tests the connection by an internal test tool straddling the connection. Two methods may be employed:

1. Hydrotesting: A tool activated by water pressure which expands opposing cup packers as illustrated in Fig. 2371. Leakage is detected by a drop in test pressure.
2. Gas testing: A wrap around device containing a helium sensing prope is installed externally onto the connection, refer to Fig. 2372. A pressurised nitrogen/helium gas mixture is applied internally to the tubing and leakage is detected by the presence of helium at the external sensing prope. Safety aspects must not be overlooked because of the high internal gas pressures, ensure gas can escape should the connection leak severely and not allow the surround to be blown off. Special safety precautions should be taken on the rig floor.

Evidence to date concludes that gas-based leak detection tools, which use a spectrometer to detect the leak, work better than the hydrostatic pressure leak detection tools (especially for gas well applications).

The standard system works with a gas mixture of 99% Nitrogen and 1% Helium. It requires a considerable amount of gas and strict safety measures. A more sensitive system uses a small volume of pure Helium gas. Water is used to pre-pressure up the system, after which Helium is used to attain the required test pressure. The advantage of this system over the other is that as less gas is required, it is safer and more sensitive. A pressure test can be performed on the connection from both sides, i.e. from the inside to the outside, or from the outside to the inside.

Field leak detection equipment may not be capable of detecting all leaking connections within a reasonable period of time, since it may take a considerable amount of time (up to 5 minutes) for the gas to percolate through the running compound trapped between the threads. The response time can be improved by limiting the quantity of thread compound applied to the connections but this increases the risk of galling and may result in high shouldering torques, hence is not recommended.

The use of ultrasonic measurements of contact stresses to assess the sealing integrity of connections in the field is being investigated. A field trial on a prototype tool was successful, although further work is necessary. The tool was developed to be able to check Finite Element Analysis stress predictions. It is based on the fact that the amplitude of an ultrasonic beam reflected from an interface is dependent on the contact pressure at that interface.

In many instances where tubing inspections and preparations are rigidly controlled and where adequate, experienced and specialist supervision is available during the well completion with torque-turn graphic interpretation, time consuming testing procedures have been forgone. Testing is limited to being carried out against a wireline/coiled tubing retrievable plug at predetermined phases (e.g. every 20 joints) of the well completion process. As a minimum the complete completion string should be tested on reaching the required setting or packer latching depth.

10 Polymeric seals

Connections that incorporate polymeric seals will require a high degree of on-site supervision of the installation procedures to ensure that the seal is present, clean and undamaged.

11 Mill-end leakages

The major cause of mill-end leakage appears to be improper make up at the mill as indicated by the movement of the mill-end during field connection make-up. The movement causes an unfavourable redistribution of the thread compound solids which were originally plated on the threads when the mill installed the couplings.

API Specification 5CT recognises the leakage problem encountered with mill-installed couplings, and states that cleaning and inspecting threads and applying fresh thread compound before using the pipe results in less chance of thread leakage. These standards make provision for ordering API tubular goods with couplings screwed on hand tight or shipped separately from the pipe. However, it is recommended that tubing be ordered with mill-installed couplings; but if any movement of the coupling is observed during field make-up, the connection should be backed out, cleaned, re-doped and re-made.

It is preferable, particularly with CRA tubulars (with coupled connections) that the applied make-up torque and torque-turn recording is provided with each mill installed coupling.

12 Running speeds

Use should be made of swab/surge calculations to determine the maximum allowable running/pulling speeds. Note that swab and surge pressures are exerted upon the formation irrespective of the location of the tubulars being run.

When running the tubing, especially in a deviated/horizontal well, any restriction to the downward movement withnessed by a reduction in the hanging weight should be investigated to prevent buckling of the tubing.

13 Tubing spacing

The tubing may be set in compression or tension depending on the completion design.

Care should be exercised in the calculation of the tubing length due to the stretch of the tubing for accurate placement of tubing and accessories. If the extremities of blast joints and/or position of packers relative to perforations are within the extremities of the following table, consideration should be given to running gamma-ray casing or magnetised casing collar locators.

Depth / Shallower / Deeper

8,000 / 2.5 / 9.5

10,000 / 4 / 13

12,000 / 5 / 17

Note: all figures in feet.

FRP tubulars require higher safety factors than metal tubulars due to material creep which causes an increase in strain with time, which introduces "design life" concepts unique to FRP tubulars. FRP creep occurs at any temperature, but is more pronounced at temperatures greater than 75°F (24°C). They are quite flexible and prone to buckling and should always be run in tension (do not use in conjunction with compression set packers and minimise compressive loads).

14 General considerations on running completion

Some general points to remember when running the completion string include:

·Ensure that elevators, slips, and power tubing tongs are in proper working order, and correct dies are fitted. Do not use pipe wrenches for manual make up of joints. Apply pipe thread lubricant sparingly to pin and box thread, and sealing areas. Ensure that the correct torque is applied, modifying the manufacturers' recommended figure, if necessary, to suit the thread lubricant used.

• ·Drift each joint of tubing to ensure that no gloves, rags or other foreign bodies have found their way inside.
• ·Record the serial number of each item as it is made-up in the string - this includes the numbers marked on the tubing joints on receipt.
• ·Confirm the operating envelopes of the equipped are appropriate for the expected working parameters.
• ·Supervisors keeping tally should cross-check with each other from time to time to ensure that the string is being made up according to the programme.
• ·Run seal assemblies very slowly into/through packer bores.
• ·The practice of running a tubing string with a plug installed in a landing nipple situated close to the bottom of the string should be avoided. Problems with debris accumulation on top of plugs are very frequent when applying this technique making retrieval difficult. (Note the availability of equipment, such as pump out plugs, to overcome this problem).
• ·Check hanging weight up and hanging weight down methodically and accurately when required to do so.
• ·After tagging the packer with its seal assembly, ensure that any pressure build-up in the tubing can be bled-off when running the seal assembly through the packer to avoid seal damage.
• ·If required to make reference marks when setting down/spacing out, do so accurately, taking care not to damage any special surface finish.
• ·Check the completion fluid for correct composition and maintain the required levels in the tubing and annulus.
• ·When carrying out pressure tests, build-up pressure slowly, in stages to the maximum figures, maintain pressure for the recommended time, and record on a suitable pressure recorder.
• ·Note that test pressures and times may be limited if the well is perforated below the packer to be tested, since the test pressure may also act on the formation.
• ·After spacing out, drift the complete string, using suitable wireline drifts.