Addax OML137区块深水控压钻井技术

Deepwater managed pressure drilling technology in block OML137 of Addax

鲍洪志 赵向阳 张华卫 张志刚 侯绪田

BAO Hongzhi ZHAO Xiangyang ZHANG Huawei ZHANG Zhigang HOU Xutian

中国石化石油工程技术研究院，北京　100101 中国石化国际石油勘探开发有限公司，北京　100083

SINOPEC Research Institute of Petroleum Engineering, Beijing 100101, China Sinopec International Exploration and Production Corporation, Beijing 100083, China

Addax OML137区块位于尼日利亚近海，水深约83~496 m，下部井段地层孔隙压力当量密度1.92 g/cm3，破裂压力当量密度2.10 g/cm3，安全密度窗口较窄，约为0.18/cm3。采用常规钻井技术无法钻达目的层，控压钻井技术是针对窄安全密度窗口的有效技术，因此有必要开展控压钻井技术适应性评价与优选，为科学地进行选井、选层、控压方式优选和控压参数设计提供理论依据。文中建立了OML137区块控压钻井适应性评价方法，即“三步法评价体系”，主要包括必要性评价、可行性评价、经济性评价。进行了控压方式和系统优选、建立了控压钻井精细流动模型，提出了深水控压参数设计原则和井底恒压设计方法，根据优选的控压系统进行了设备配套，最后在Asanga-2井进行了应用，为以后的控压施工积累了经验。

Block OML137 of Addax is located at Nigeria offshore, with the water depth of 83 to 496 m. The formation pressure coefficient of the lower well section is 1.92 g/cm3, and the breaking pressure coefficient is 2.10 g/cm3, so the safe density window is relatively narrow, about 0.18 g/cm3. The target zone cannot be reached by conventional drilling. Managed Pressure Drilling (MPD) technology can resolve narrow MW window problem effectively. So it is necessary to conduct MPD adaptability evaluation and optimization to provide theoretical basis for scientifically selecting well, selecting section, optimizing MPD method, and parameter design. The adaptability evaluation method for MPD in Block OML137 was established, namely “Three-step Evaluation System”, including necessity, feasibility and economy evaluation. The method and system of pressure control were optimized, fine flow model of MPD was set up, and the principles of deepwater MPD parameter design and the design method of bottom hole constant pressure were put forward. The equipments were coordinated in accordance with the optimized pressure control system. The technique was applied to Well Asanga-2, which supplied a reference for future pressure control treatment.