RESL completed an independent review of BP’s Southern North Sea portfolio with Halliburton over a 12 month period in 2011.
The scope of work included a decommissioning assessment of BP’s 24 operated platforms and associated infrastructure (pipelines and subsea wells) and addressed expansion of the scope to include 27 additional BP non-operated platforms. The study also covered 83 pipelines, 49 umbilicals, 54 manifolds & templates and 151 wells. The class of estimate was AACE Class 4 for fields within 5 years of cessation of production & AACE Class 5 for remainder.
In order to address the scope of work as set forth in the scope of work, RESL created specific report sub-sections to address the following topics:
- Contracting Strategy
- Law & Regulation
- Review of BP SNS Field Data
- Cost Estimating Methodology
- Well Abandonment
- Conductor Removal
- Reverse Installation (topside and jacket)
- Piece Small Topside Removal
- Pipeline & Subsea Infrastructure
- Disposal
- Summary of Cost Estimates
Halliburton provided RESL with technical, cost and operational input into the well P&A and contracting strategy sections of the study.
Historical well P&A costs from Halliburton and RESL databases provided the basis for the BP SNS well abandonment estimate presented in this report. The well P&A work included evaluating over 151 wells for decommissioning.
In order to better define these historical abandonment cost and methodology, three abandonment well types were defined. These types are based on previously used methods that meet current abandonment guidelines in the UK Southern North Sea (SNS) and are described as follows:
- Well type I represents wells that can be abandoned using the rigless approach with operations limited to wireline and pumping.
- Well type II represents wells that can be abandoned using the rigless approach but will likely need to use coil tubing to spot one or more of the cement plugs.
- Well type III represents wells that will need to use a HWO unit to pull the tubing and mill a casing section to complete the abandonment.
This successful study has lead to on-going close co-operation between RESL and Halliburton on other well P&A studies and fieldwork worldwide.