Challenging environments such as unstable clay formations represent high operational risk when running tubulars after drilling is completed. Use of steerable-drilling-liner (SDL) systems combines drilling and casing of the hole, thereby mitigating the risk of not being able to run the liner because of time-dependent formation collapse. This case study presents the difficulties encountered with conventional approaches with a semisubmersible rig in the North Sea during 7-in.-liner-running operations in an unstable clay formation and details a subsequent SDL operation.
Midgard, a subsea field, is part of the Åsgard Licence and is located in the North Sea. Midgard consists of three templates with four slots each. Production from the field goes to the production platform Åsgard B. The primary objective of this well was to increase reserves, accelerate production, and add robustness. The secondary objective was to evaluate the potential of this segment. The target in the reservoir was approximately 4 km from the template at a depth of 2500-m true vertical depth (TVD), making this well almost an extended-reach well. This paper will only focus on the 8½-in. section....
Steerable-Drilling-Liner Technology in Unstable Shale
01 June 2016