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LUKOIL's drilling operations on Korchagina field offshore Caspian, involving 16 extended reach wells were recently culminated by completing the longest well on the project. Well P-108 was planned to the total depth of 9000 mMD and required precise engineering and special techniques especially with respect to lower completion installation. This paper provides a case history of the challenging lower completions deployment along with the well design summaries and operational parameters that led to successful execution. Based on the previous experience, installation of the lower completions on the long reach wells requires rotation. With a standard lower completions design incorporating sections of 6⅝-in and 5½-in stand alone screens, the torsional loads were exceeding torque limitations of the completions and running strings. The approach used for this well was based on the best design and operational practices from the previously drilled extended reach wells and comprising of selection of optimal screen sizes, running string optimization, friction factor reduction, hole condition management, cooperation with geomechanics and well placement teams throughout the course of drilling the section was planned on this well for successful execution. The well was successfully drilled and completed at a shallower total depth than planned - 8005 mMD, due to geological reasons. Nevertheless, this well broke several records on the project: the longest well, the longest completions string – 5032 m, the highest daily footage in 9½-in section – 837 m. It also broke one of the world records: the longest 9½-in one bit run – 4895 m. During well planning and execution stage, key elements of well design and implementation were subjected to intense analysis through systematic optimization processes. Along with management of well construction parameters and practices, this resulted in technical integration of multiple discipline, such as well engineering, completions engineering, geomechanics, mud engineering, well placement, directional drilling. Understanding the key challenges of the well and collaborative work between an operator and service providers in addressing the issues, allowed to achieve exceptional results in drilling and completing the longest well on the project without HSE or environmental impact. Successful execution of the well has established new benchmarks on the projects and on the Northern Caspian and pushed the limits of extended reach drilling (ERD) wells on Korchagina to world class ERD wells. Design considerations and applied techniques provided in this case history can be used for the future ERD wells with non-trivial conditions with regards to the lower completions installation. |
