顺北5-8井志留系破裂性地层提高承压能力技术

新疆顺北区块古生界志留系地层由于地质构造运动强烈，断裂带附近缝网发育，且深层存在高压盐水层，钻井液安全密度窗口窄，井漏严重且高发。针对志留系防漏堵漏技术难点，深入分析了志留系破裂性地层漏失特性，通过地质、测井、岩屑等资料分析漏层岩性及孔渗特征，根据实钻数据、测井和水力学等方法分析漏层通道的大小和连通情况，对地层承压能力影响因素进行了细致分析，针对主要裂缝地层开发了抗高温致密承压堵漏配方，并根据不同的漏失类型制定了"随钻封堵、逐步强化、分段承压、稳步推进"的防漏堵漏技术思路，在顺北5-8井进行防漏堵漏作业13次，均获成功，有效提高了地层承压能力，井漏复杂处理时间同比大幅度减少60%。 

Technology for Enhancing Pressure Bearing Capacity of Fractured Silurian System in Well Shunbei 5-8

Lost circulation is a severe downhole trouble frequently encountered in Block Shunbei in Xinjiang because of fractures around the fault zones resulted from strong geological movement in the Paleozoic Silurian System, high pressure formation saltwater and narrow safe drilling windows. In this paper, the characteristics of the mud losses occurred at the fractured Silurian System are extensively analyzed. The sizes and connectivity of the channels in the lost circulation zones are analyzed using actual drilling data, wireline logging data and hydraulic data, and factors affecting the pressure bearing capacity of the formations are carefully analyzed. A high temperature lost circulation material (LCM) slurry for the main fractured formations to make them dense was developed and a lost circulation control procedure, that is, "plugging while drilling, gradually strengthening, enhancing pressure bearing capacity section by section, and drilling steadily ahead", was formulated. This LCM slurry and the procedure were applied in Well Shunbei 5-8 for 13 times, all succeeded, greatly improving the pressure bearing capacity of the fractured formations. Time spent dealing with lost circulation has been reduced by 60%.