Enteron Services Limited

Simple and functional, our 400Te Tension Table is designed to take the load off the wellhead while intervention or repairs are carried out.It can be adjusted, adapted, and re-engineered quickly to suit your needs.

400TE WELLHEAD TENSION TABLE

Take the load off.

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The use of Enteron Tension Tables is becoming more frequent during Intervention and drilling operations, due to integrity issues with ageing assets.

The integrity of the casings and conductors are hugely important and if neglected can result in the well collapsing causing the wellhead, Xmas tree and associated surface equipment to fall through the wellhead areas damaging everything in its path i.e. rupturing flow lines, hydrocarbon release etc.

This has occurred in the North Sea, and worldwide, to devastating effect. To prevent this type of incident operators are increasingly taking preventative action by monitoring the condition of the casings on their respective assets.

The casing monitoring programme is an on-going activity and involves the use of monitoring equipment to measure the corrosion in the casing on a regular basis.

These are known as PEC surveys (Pulsed Eddy Current). Monitoring equipment is inserted into the C annulus and records the thickness of the casing/conductor. This is compared to the next set of readings and analysed by the structural engineers who decide what safety factor is to be applied to each well.

If the integrity of the casing deteriorates significantly and falls below a predetermined safety factor (1.3) as advised by the structural engineer, this forms the basis to implement the use of an Enteron Tension Table during well services and drilling interventions.

Various well operations such as pumping cold fluids during scale squeezes, or glycol displacement, can cause the well to contract and large forces can be generated and applied to the casing. The use of an Enteron Tension Table at surface will support the weight of the wellhead and unload the

Overview

400TE Well Head Tension Table

structural casings during the intervention or drilling activity.

The Enteron Tension Table supports not only the weight of the wellhead and casing, but also the weight of the surface equipment rigged up above the Xmas tree PCE equipment (Riser, BOP, coiled tubing or wireline equipment) preventing additional weight being applied to an already badly corroded well.

Our tension tables are rated for 400te but can be increased to 800te if required. The limiting factors are usually the studded flange connections on top of the Xmas tree and the riser bolted flange connection sections from the Enteron Tension Table to the top of the Xmas tree/wellhead . In certain applications, high tensile bolts can be provided, which will allow larger weights to be supported by the

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Figure 1 Example of Wellhead slippage due to corroded casing

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Challenge:Operations were being carried out on ageing wells with known corrosion issues and additional loads were being applied to an already weak structure without any protection being in place.

This resulted in a collapsed well on a North Sea asset, resulting in significant damage.

Solution:Use of an Enteron Tension Table and risers to support additional loads being applied, and also to support the well should it collapse during interventions.

Results:By using an Enteron Tension Table it allowed the client to enter numerous wells safely. On this occasion it allowed the pre-abandonment work to be completed knowing that no additional load was being applied to the well at surface. In the event that the extra loads applied during circulation of cold fluids affected the integrity of the casing, the weight of the well was fully supported by the Enteron Tension Table.

• Pressure test tubing hanger and casing hanger seals• Rig up Enteron Tension Table, Slickline and test.• RIH and conduct drift run to WRSSSV• RIH and retrieve WRSSSV• RIH and conduct drift run for deep set plug• Rig down Slickline and rig up E-line• RIH and set a 5.34” Magna plug @ 9,910ft• RIH and Punch Tubing

• Circulate tubing and annulus to inhibited seawater• Pressure test 9 5/8” Packer and Magna Bridge Plug• Rig down E-line, Rig up Slickline and test• RIH and set Huge Bore Dummy• RIH and set Shallow Plug in 7” 29# tubing @ 90ft• RIH and set catcher / Prong in 7” plug and test• Rig down Enteron Tension Table Slickline/and hand well back to ops

Well BA03 was a candidate for abandonment and upfront well Intervention work was required as listed below:

Client Case Study :- Well 03, for a Major North Sea operator

Due to structural issues with this well, the only way any intervention work could be undertaken was by utilising a 400 tonne Enteron Tension Table.

The following workscope was successfully completed utilising the Enteron Tension Table and flanged riser. The well is now ready to be fully abandoned when the drilling activity commences. All the preparation work has been completed, thus saving costly rig time.

Figure 1 below shows what can happen if casing integrity is not monitored regularly.

C Annulus Bull plug sheared off

A number of bolts have been strapped to the Casing head to halt further slippage

400TE Well Head Tension Table

www.enteron.co400TE Well Head Tension Table

Applicable Globally

• Allows intervention work to be completed safely

• Demonstrating that casing integrity has been addressed and the RISK has been categorised ALARP in the event of any incident investigation

• If known casing corrosion figures are available it can be easily determined if an Enteron Tension Table is required or not

• If casing corrosion figures are not known, then as a precaution to maintain Well Integrity and reduce the risk of collapse of a well to ALARP, it is advisable to use an Enteron Tension Table during any well intervention. See figure 1

• Use of flanged risers reduces the potential for O ring failure in the PCE during wireline operations ie only one O ring below the wireline BOPs .

• Using an Enteron Tension Table will enhance a company’s commitment to addressing integrity issues

Key Benefits of using an Enteron Tension Table

• Currently in use worldwide• Has been used extensively in the North Sea for a major operator • Stable in temperatures as low as minus 25 degrees centigrade

For further information on the Enteron Wellhead Tensioning Systems please contact:

Enteron Services 39 Queen's RdAberdeen | AB15 4ZNScotland | United Kingdom

+44 1224 430100