Extending Lateral Length Using Casing Floatation to Reduce Field Development Cost in Shale Gas Plays

Abstract

Operating in a low margin gas environment, operators look for new ways to reduce costs and efficiently develop reserves. Shell Canada Limited ("Shell"), operating in the Montney shale gas field located in NE British Columbia, Canada, used casing floatation techniques to extend lateral lengths. Increasing lateral length reduces well cost per lateral meter. This is because drilling the reservoir section is the least expensive segment due to high penetration rates. Extended lateral lengths also create new options for more economical and sustainable field development as fewer wells are required to cover acreage and it reduces dead space. Shell uses a mono-bore casing design with average lateral lengths of 1800m at a TVD of 2300m. The goal of the project was to double lateral length to 3600m. At these depths, extending much beyond the current design is not possible due to theoretical casing lock-up from excess drag during conventional casing running. Casing floatation was chosen to extend the lateral reach of the wells and mitigate casing lock up because it is a cost effective, simple technology. Casing rotation and setting a deep intermediate string to reduce drag were also evaluated but deemed too cost prohibitive or technically unfeasible. This paper documents the process and successful results of Shell's undertaking in doubling lateral length using casing floatation technology on five test wells in the area. It also provides detailed evaluation of post-run data to calibrate casing running models and the future impact of these results on an economical field development.

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