超深层致密砂岩储层构造裂缝特征与有效性——以塔里木盆地库车坳陷克深8气藏为例

构造裂缝特征分析及有效性评价对库车坳陷克深8气藏致密砂岩储层有利区预测和开发措施的制定具有重要意义。综合利用岩心、成像测井和单井产能等资料，明确了克深8气藏构造裂缝的基本特征与形成序列，分析了构造裂缝发育的影响因素，最后对构造裂缝平面上和纵向上的有效性进行了评价，并提出了开发措施建议。结果表明：克深8气藏的构造裂缝以直立缝和高角度缝为主，部分裂缝被硬石膏、白云石和渗流砂颗粒充填，上新世库车组沉积期形成的第3期构造裂缝是克深8气藏最重要的一期构造裂缝；构造裂缝发育程度受断层、岩性、岩层厚度和沉积微相等因素的影响。背斜高部位的构造裂缝有效性好，是天然气的高产区，现今水平最大主应力方位与构造裂缝优势走向呈大角度相交时，会显著降低构造裂缝的有效性；不整合面对构造裂缝有效性的控制主要集中在距不整合面下方约70 m的范围内。对克深8气藏巴什基奇克组储层的开发措施应以压裂为主，并且优先开发第3砂层组，其次为第4砂层组及以下地层，最后考虑第1、第2砂层组。

Characteristics and effectiveness of structural fractures in ultra-deep tight sandstone reservoir: A case study of Keshen-8 gas pool in Kuqa Depression,Tarim Basin

Characteristics analysis and effectiveness evaluation of structural fractures are of great significance to predict favorable tight sandstone reservoir and to select development strategy in Keshen-8 gas pool,Kuqa Depression,Tarim Basin.We analyzed the basic characteristics and forming sequence of the structural fractures,and the factors influencing their growth through such data as core,image logging and single well productivity.In the end,the planar and vertical effectiveness of structural fractures was evaluated,and some suggestions for development were given.The results show that (1) the structural fractures,partly filled with anhydrites,dolomites and seepage sand particles,are mainly upright or have a high dip angle.The third-phase structural fractures developed during the deposition of the Pliocene Kuqa Formation are the most important ones for gas preservation in Keshen-8 gas pool.(2) Faults,lithology,stratum thickness and sedimentary microfacies function to control the development of structural fractures.Structural fractures on the upper part of anticline are highly effective,but their effectiveness would decrease dramatically when their dominant orientation intersects with the direction of present maximum principal stress at a large angle.(3) The controlling effect of unconformity on structural fracture effectiveness is limited within 70 m to the unconformity.The Bashijiqike Formation reservoirs in Keshen-8 gas pool should be produced primarily through hydraulic fracturing,and top priority should be given to the 3^rd sand unit in development,followed by the 4^th sand unit and its underlying reservoirs,and the 1^st and 2^nd sand units being the last ones.