To increase and optimize single well production performance, multilateral drilling and completion technology were implemented from a new single wellbore deep in the Tarim Desert of the Xinjiang Province in northwestern China.

Although planning and preparation began in earnest in Tianjin months in advance of the actual installation, the on-site demands, distant logistics support, and the well depth operational demands of the project installation were the most challenging steps in the process. The remote location of the multilateral well in the Tarim Desert proved to be an operational and logistical challenge in terms of time (4- to 5-days travel time by vehicle) and distance (3600 kilometers) to the nearest repair and maintenance facilities in Tanggu, Tianjin Province in eastern China.

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 another wellbore, thereby increasing reservoir exposure. The goals of this system were to accelerate production, increase ultimate recovery and, for this particular operator, qualify multilateral technology for application in this specific field. 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 mitigate risk and to promote a successful project installation.

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. This was also the first multilateral installation by Tarim Oil Company and the first cemented Level 4 multilateral installation in China. This paper describes the objectives, challenges, best practices, contingencies, logistics issues, results, and lessons learned from the implementation of this deep-set multilateral technology.

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