Casing Exit to Casing Entry - A Novel Concept for the Abandonment Process in Intersect Applications

Abstract

The number of mature wells worldwide requiring abandonment intervention is rapidly gaining exposure again as the industry recovers. Current access to the completion, using straightforward methods of barriers to satisfy regulatory standards, is the primary means of completing the life cycle of a well. Other methods require an intersect process into the existing wellbore for the abandonment to be considered compliant. Using whipstocks to assist with the intersect can reduce time vs. conventional methods.

Traditional methods of intersecting wells involve drilling or milling into the existing wellbore using directional assemblies, usually after a sidetrack operation up hole. This process of trying to breach into the existing well can be problematic and result in multiple unsuccessful attempts, driving up operational spend. Rather than leaving an intersect to chance, a whipstock can be used as a diverter to increase the likelihood of success while also controlling depth and direction more accurately. Once run into the well and anchored, the whipstock also acts as a re-entry guide for intervention and abandonment operations.

An in-depth analysis of a recent abandonment operation, where both directional assemblies and eventually a whipstock was used to intersect existing casing for abandonment and to highlight the advantages and pain points associated with both methods. Through detailed preplanning, intensive logging, wellbore preparation, and prior experience, the whipstock operation was successful relative to prior attempts with conventional methods. The intersect and following abandonment process were not completed without lessons learned. Hole conditions, an up-hole casing exit junction, and custom cement blends were a few of the areas of focus for future improvement on efficiency. Even with operational challenges, the whipstock operation reduced time spent intersecting the well.

This paper shows that whipstocks are a viable option to reduce time spent intersecting wells for abandonment purposes. This case history provides the industry an opportunity to replicate this success in similar applications.