Multilateral History - Deepest Level 4 Cemented Junction Installation

Abstract An operator was challenged with increasing production efficiencies from new single wellbores in the deep Tarim basin reservoirs of China. To increase and optimize single well production performance, multilateral drilling and completion technology were implemented on this initial pilot test well. The remote location of the multilateral well in the Tarim Desert of the Xinjiang Province in northwestern China proved to be an operational and logistical challenge in terms of time (4 to 5 days travel by vehicle) and distance (3600 kilometers) to the nearest repair and maintenance facilities in Tanggu, Tianjin Province in eastern China. Critical planning, aggressive project management oversight, and strong collaboration between the operator and service supplier resulted in the world’s deepest TAML Level 4 cemented multilateral installation at 5082 m TVD junction depth and 5889 m MD at the lateral toe. The well design was based on a vertical pilot well, or motherbore, drilled and cased into the reservoir. The multilateral system was then installed to add an additional wellbore, thereby increasing reservoir exposure. The goals of this system were to accelerate production, increase ultimate recovery and, for this particular operator, to qualify multilateral technology for this particular field application. Because of the unprecedented depth of the proposed junction, thorough project management and planning were required throughout, from the feasibility phase through the execution phase, to amplify risk mitigation and to effect a successful project installation. This project is the first multilateral installation for this client; it was the first cemented Level 4 multilateral in China, and is the deepest Level 4 multilateral installed worldwide. This paper describes the objectives, challenges, best practices, contingencies, logistics issues, results, and lessons learned from the implementation of this deep-set multilateral technology.