Rigless P&A Support

Case Summary

Our client has targeted to plug and abandon over 2000 wells, across a large number of offshore platform, over a period of 4 years in the Gulf of Thailand. The scope of work and time constraints require solutions to both limit costs and increase the rate of P&A completion per well. In other words the most efficient solution possible is required.

Many variations of rigless modular methods of P&A have been developed to solve these very challenges. The advantages of rigless methods are well documented from a cost and time standpoint. In all cases modular rigless methods in P&A campaigns will require lifting support, either by platform cranes, vessel cranes, temporary modular cranes, or all the above in combination, especially if applied over large scales.

Rigging Up Modular Rigless Units on Offshore Platform

In the Gulf of Thailand many of the platforms do not have sufficient lifting capacity to cope with the demands and the efficiency required by the client.

Platform cranes are too small for the most efficient HWU or jacking/pulling (RPU) packages. On some platforms where there was no platform crane or the platform crane was under-rated or not serviceable, a mobile crane was necessary to rig up the HWU or RPU.

Therefore for this campaign the TC90 modular crane is deployed on platforms to lift material and equipment to/from supply vessel and offshore platform deck, including the heavy lifting of modular HWU or RPU and associated components such as BOP. When on platform deck TC90 also provides the necessary lifting support for the assembly and dis-assembly of the HWU and RPU.

Increasing the rate of RPU pulling tubulars with a TC90 Crane

In well abandonment work running and pulling tubulars is one of the principle time consuming tasks. Here the TC90 modular crane system is perfectly designed to complement and support jacking units such as the RPU (rigless pulling unit).

• RPU is used to run fishing tools, cutting tools, completion tools, provide rotary services and jack or break the pipe free.
• Once RPU has jacked the pipe free the TC90 crane can pull tubulars in joints which is faster than jacking out of the hole with RPU.
• The TC90 crane can then lower the tubing joint to the platform deck and lay it down before returning to basket elevation.
• A lay-out operation takes approximately 2.5 to 3 minutes per joint and time is saved on every joint

Overcoming space constraints with a TC Extension Deck

Smaller platform present space constraint challenges when working with either RPU or HWU and modular crane. We were able to overcome these challenges by combining our TC Extension Deck and TC90 Modular Crane in one package which maximises the usable area on a platform.

• TC90 beams allow for a deck with dimensions 10m long x 7m wide that can hold 55mt of equipment.
• Mitigate point loading caused by large packages directly placed on the platform deck.
• Extend and cantilever beyond the edge of the offshore platform by approximately 15 feet.
• Enable staging of larger equipment and/or packages that require minimum movement, or minimum access during operations.
• Minimize shuffling of equipment on deck for quicker transitions from well-to-well.​

Leap-Frogging to Maximise Efficiency

When moving HWU/RPU from platform to platform the logistics of “leap-frogging” are applied to both advance the project schedule, and reduce costs. This works in the following manner:

• Just a few days before the HWU/RPU unit (say platform A) is to be moved to another platform (say platform B) once the job on platform A is completed, rigging up the a second crane on platform B will save precious time to receive the HWU/RPU unit from platform A and rig up the HWU/RPU on platform B.​
• If the same crane from Platform A is to be used on Platform B, the HWU unit will require to be on stand-by while the crane from Platform A is to be rigged up, inspected and ready to be used on Platform B. ​
• HWU/RPU day rates are high, and when abandoning a large number of wells over multiple offshore platforms each HWU/RPU day saved over duration of the P&A campaign adds up. ​
• The crane on Platform A can now be rigged down, moved out and rigged up on another platform (say platform C) ready to receive another HWU/RPU unit.​