Expanding the Extended Reach Envelope at Chayvo Field, Sakhalin Island

Abstract

Abstract The second drilling campaign at the Chayvo field, located offshore Sakhalin Island, targeted the development of a new reservoir zone using extended reach wells from onshore. A total of 4 oil producers and 1 gas injector were planned to develop the northern portion of the reservoir. To effectively drain the east and west flanks of this reservoir, record length wells beyond the current extended reach drilling (ERD) envelope were required. Key challenges included high torque and drag, wellbore positioning in a thin oil column, wellbore stability, long horizontal completions, and downhole tool telemetry. This paper describes the Operator's experience with drilling these challenging wells that resulted in several new ERD records. Key well design features, equipment upgrades, and lessons learned will be discussed. ERD is an established technique to economically access reserves from existing infrastructure, reducing the need for additional drill centers and consequently reducing the drilling and facilities environmental footprint. Continuing advancement of the ERD envelope along with delivering cost-effective wells will further maximize the benefits of this technique. The case history described in this paper illustrates that the advancement of the ERD envelope is possible through detailed planning, technical design, and operational excellence. The planning of these wells built upon the Operator's previous ERD experience along with additional tools and techniques. Three of the project wells set new worldwide ERD records for measured depth; the longest well, Z-42, established new records for measured depth (12,700m) and horizontal reach (11,739m). Completion designs were optimized to successfully run a ∼3,600m long open hole completion, and the well was finished in ∼70 days. As a result of this successful development, additional wells are being planned in conjunction with technology advancement initiatives that will push the ERD measured depth envelope to 13km and longer.