Integrated Development of the Changbei Tight-Gas Project

This article, written by Assistant Technology Editor Karen Bybee, contains highlights of paper IPTC 11408, "Integrated Development of Changbei Tight Gas Project," by Guilin Luan, SPE, Lin Li, Gary Nettleship, SPE, Luc Van Son, and Taco Hoekstra, Shell China E&P; Robert Deutman and Sieward Veeman, Sarawak Shell Bhd.; and Hua Wang, PetroChina ChangQing Oilfield Co., originally prepared for the 2007 International Petroleum Technology Conference, Dubai, UAE, 4-6 December. The paper has not been peer reviewed. Changbei is an onshore tight gas field in north Shaanxi Province, China. The main reservoir is a thin and fairly complex braided-channel sandstone formation with a 5% average porosity and a 0.7-md permeability. For field development, a dual-lateral well with two 2000-m horizontal sections was selected. After a summary of the development-concept selection and the status of the project, the full-length paper details some of the development challenges. Introduction A production-sharing contract (PSC) was signed between PetroChina and Shell in 1999 to develop the Changbei gas field, followed by a 2-year extensive evaluation and appraisal period to prepare a development plan. Appraisal activities performed included fracturing existing and newly drilled vertical wells and drilling/testing horizontal wells. The Changbei tight-gas development is the largest onshore cooperative venture between an integrated oil company and one of the three Chinese oil majors in terms of investment and development scale. In addition to difficult reservoir conditions, challenges specific to the local environment had to be overcome [e.g., technology and equipment availability; local-contractor competence; community relations; and high health, safety, and environment (HSE) standards]. Field History Exploration drilling in the Changbei Block began in 1991. The first small-scale gas production to supply the local community was recorded in 1995. Seismic was used to predict the lateral continuity of the reservoir-sand body and reservoir boundary, leading to an extensive exploration campaign during 1996–97, culminating in a successful well test. Two-hundred-fifty 2D-seismic lines with a 3800-km approximate length were acquired. Twenty exploration wells, nine development wells, and two appraisal wells were drilled before field-scale development planning and project execution. All wells were vertical except the two appraisal wells, where both vertical and horizontal sections were drilled. Basic well tests were conducted on most of the wells. Trial production on 16 wells began in November 1999, which provided valuable information on well/reservoir dynamic behavior and helped gain production experience with vertical and hydraulically fractured wells in the tight gas reservoir.