Part of a multi-year, multi-platform plug and abandonment campaign that began in 2019, the following case study provides a description of how Thunder Cranes’ TC90 modular crane performs a key role in supporting both HWU and RPU in rigless P&A for Chevron, Thailand.

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).

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.

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:


In the deployment of rigless modular HWU or RPU for P&A it is shown that adding our TC90 modular crane and extension deck packages to the HWU/RPU package allows for a more efficient operation. Further improvements are brought about by applying multiple TC90 modular cranes to enable the application of "leap-frogging" in rig-move logistics.






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