玛湖凹陷三叠系百口泉组致密砾岩储层水力裂缝特征及形成机制  

Characteristics and formation mechanism of hydraulic fractures in tight conglomerate reservoirs of Triassic Baikouquan Formation in Mahu Sag

作　　者：覃建华[1] 王建国[2] 李思远[1] 李胜[1] 窦智 彭仕宓[2] QIN Jianhua;WANG Jianguo;LI Siyuan;LI Sheng;DOU Zhi;PENG Simi(Research Institute of Exploration and Development,PetroChina Xinjiang Oilfield Company,Karamay 834000,Xinjiang,China;China University of Petroleum(Beijing),Beijing 102249,China;Urumqi Branch,Research Institute of BGP,CNPC,Urumqi 830026,China)

机构地区：[1]中国石油新疆油田公司勘探开发研究院,新疆克拉玛依834000 [2]中国石油大学(北京),北京昌平102249 [3]中国石油东方地球物理公司研究院乌鲁木齐分院,乌鲁木齐830026

出　　处：《岩性油气藏》2023年第4期29-36,共8页Lithologic Reservoirs

基　　金：中国石油科技创新基金项目“致密油储层微-纳米孔隙构建系统与润湿性的耦合机制”(编号:2019D-5007-0202);中国石油天然气集团有限公司-中国石油大学(北京)战略合作科技专项“准噶尔盆地玛湖中下组合和吉木萨尔陆相页岩油高效勘探开发理论及关键技术研究”(编号:ZLZX2020-01)联合资助。

摘　　要：水力裂缝的分布规律对致密砾岩油藏高效开发至关重要。通过对玛湖凹陷已压裂砾岩油区的水平取心井MaJ02井的岩心裂缝观察,剖析了玛湖凹陷三叠系百口泉组致密砾岩储层中水力裂缝的类型、产状、组系、开度、密度及支撑剂充填情况,明确了其分布特征,并探讨了其形成机制。研究结果表明:(1)玛湖凹陷MaJ02井百口泉组岩心中发育的水力裂缝条数占总裂缝数的77.6%,走向为90°~110°,倾角为70°~90°。(2)研究区主要发育以走滑机制形成的剪切缝,占比为65.8%,其次为张应力形成的张性缝,占比为34.2%。剪切缝多成组出现,开度较小,多为全充填,裂缝面以“穿砾”为主,多条裂缝叠加而形成缝网破碎带;而张性缝多为单条出现,开度相对较大,裂缝面不规则,为全充填或半充填,裂缝面以“绕砾”为主。(3)研究区取心井与已压裂井距离越小,压裂段射孔簇间距越小,水力裂缝密度越大。在压裂工程条件相同的情况下,泥质支撑漂浮砾岩相和前缘席状砂微相的裂缝相对发育,砂质含量越高,水力裂缝密度越大。The distribution of hydraulic fractures is very important for the efficient development of tight conglomerate reservoirs.Through the observation of fractures in the core from the horizontal coring well MaJ02 in the fractured conglomerate oil area of Mahu Sag,the type,occurrence,formation,opening,density and proppant filling of hydraulic fractures in the tight conglomerate reservoirs of Triassic Baikouquan Formation in Mahu Sag were analyzed,their distribution characteristics were clarified,and the formation mechanism was discussed.The results show that:(1)The hydraulic fractures developed in the cores of Baikouquan Formation in well MaJ02 account for 77.6%of the total number of fractures,with a strike of 90°-110°and a dip angle of 70°-90°.(2)The shear fractures formed by strike-slip mechanism in the study area account for 65.8%,followed by tensile fractures formed by tensile stress,accounting for 34.2%.Most of the shear fractures are in groups with small openings and fully filled,and the fracture surface is mainly through gravel,and multiple cracks are superimposed to form a fracture network fracture zone.The tensile fractures are mostly single with relatively large openings and irregular fracture surface,which are fully or half-filled,and the fracture surface is mainly surrounded by gravel.(3)The smaller the distance between the coring well and the fractured well in the study area,the smaller the perforation cluster spacing in the fracturing section,and the greater the hydraulic fracture density.Under the same fracturing engineering conditions,the fractures of argillaceous supported floating conglomerate facies and front sheet sand microfacies are relatively developed.The higher the sand content,the greater the hydraulic fracture density.

关 键 词：致密砾岩 水力裂缝 张性缝 剪切缝 形成机制 百口泉组 三叠系 玛湖凹陷 

分 类 号：TE122.2[石油与天然气工程—油气勘探] P618.13[天文地球—矿床学]