Sapura Energy(Drilling Contractor)has developed a lightweight drilling package for a long-term plug and abandonment(P&A)campaign,designed to deal with wellbore uncertainties while remaining light enough to be rigged up on aging platforms.The package was deployed in conjunction with the Sapura Alliance Semi-Tender unit. A drilling contractor recently developed a lightweight drilling package for a long-term plug and abandonment(P&A)campaign in the Asia Pacific region.The drilling package,was deployed in conjunction with a semi-tender rig in early 2018.It was developed directly in response to an operator’s request for a safe and economical P&A solution. Driven by the belief that there is not one-size-fits-all solution for P&A,the contractor began by carefully comparing the full P&A campaign costs versus a simple dayrate.This was done under the recognition that, while some options may be cheaper on a day-to-day basis,they may not able to perform the full scope of work or may require significantly more time to complete the work.A bespoke solution would be needed for this project by using data from the wells,platforms and the environment,as well as the understanding that some data might be missing or inconsistent due to age. Due to the track record of tender-assisted operations in the region,existing rigs were first screened for this project.However,it was soon recognized that all existing drilling packages were too heavy to access all the platforms required due to their ages and,therefore,their reduced payload compared with their original designs.Furthermore,by the ages of the wells that were to be plugged and abandoned,there was a great level of uncertainty concerning what to be found in those holes once operations began.The operator wanted a solution that could not only perform basic operations but also adapt to unexpected situations without having to mobilize additional equipment. For a drilling contractor,this meant developing a solution that could handle significant uncertainties yet could remain light enough to be rigged up on aging platforms. Hydraulic workover units,sometimes called rigless units,and lightweight conventional drilling packages were considered. The hydraulic/rigless models studied were compact and did not rack pipes in the derrick.This would save time during rig-up and rig-down,but it also meant that the rig would only be able to trip in single or double, compared with triple for the conventional drilling package.Studies conducted during the initial phase of the project showed that the hydraulic/rigless model’s potential time savings during rig-up and rig-down would be neutralized by the slower tripping speed. The drilling package that was ultimately developed for this project can transfer pipes to and from the drilling equipment set(DES)at any time;no cranes are required.This is particularly useful when there are supply vessels to be worked on and,for example,casings to be brought back off the tender unit.Both operations would be able to be conducted simultaneously because they involve two separate systems.In comparison,the hydraulic/rigless model relies on cranes for transferring tubulars from the platform to the support vessel. In both cases,the large deck space on the tender unit would help to reduce supply vessel movement because almost all of the retrieved tubulars from the platform can be kept onboard prior to back loading. The large accommodation also allows any pre-decommissioning crews to be onboard and perform any inspections or other required tasks without mobilizing additional vessels. Tilting the selection in favor of the conventional package was the fact that there has already been decades of innovation in terms of offline activities.Designs that have reduced drilling time in the Gulf of Thailand from 70 days in the 1970s to less than five days now were applied to this project.For example,cement plugs could be circulated out on one well while tubing is pulled on another.The contractor’s experie
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