A Case Study of Design and Installation of Upper Completion System for a Deepwater Gas Field in South China Sea

Abstract

The urgent demand to replace the rapidly declining conventional reserves is driving China's operators to accelerate the development of deepwater reservoirs. SHENHAI Project is the first deepwater project operated by CNOOC China Ltd., locates in water of 1220m to 1546m in South China Sea. Deepwater completions differentiate themselves not only by unique technical challenges, but also by their high cost, risk, and long project cycles. A sound project management process is essential to ensure flawless execution. By reviewing the key steps of the SHENHAI deepwater completion campaign, such as upper completion design, critical equipment selection, interface management, workshop preparation, and final project execution, lessons learnt, etc., this paper provides both a job cycle of completion design-to-execution and a methodology to manage a complex project by addressing the challenges inherent in the deepwater completion process. As a result, the well completion campaign was completed ahead of schedule. A total of 11 deepwater wet-tree wells were successfully delivered as designed including two dual-zone hydraulic controlled intelligent wells. The upper completion design has been proven to be safe and reliable with first applications of several critical upper completion tools in the region, such as Nitrogen-Charged Surface Controlled Sub-surface Safety valve (SCSSV), Hydrostatic-Setting production packer and quartz-based permanent downhole pressure gauge. This success demonstrates the completion design and practices are applicable for this deepwater project and can be extended to further offset deepwater projects in this area. This paper describes case details of successful upper completions of SHENHAI project aiming to provide information and experiences for engineers who may face the similar challenges.