鄂尔多斯盆地西部油区延长组致密油储层裂缝测井评价  

Log Evaluation for Tight Oil Reservoir Fractures of Yanchang Formation in Western Oil Region of Ordos Basin

作　　者：林利飞[1] 高毅[1] 尹帅 胡国祥[1] 马绒利[1] 张小莉[3] LIN Lifei;GAO Yi;YIN Shuai;HU Guoxiang;MA Rongli;ZHANG Xiaoli(Yanchang Oilfield CO. Ltd., Yan’an, Shaanxi 716000, China;School of Earth Sciences and Engineering, Xi’an Shiyou University, Xi’an, Shaanxi 710065, China;Department of Geology, Northwest University, Xi’an, Shaanxi 710069, China)

机构地区：[1]延长油田股份有限公司开发部,陕西延安716000 [2]西安石油大学地球科学与工程学院,陕西西安710065 [3]西北大学地质学系,陕西西安710069

出　　处：《测井技术》2022年第1期95-101,共7页Well Logging Technology

基　　金：延长油田公司开发部项目“延长油田西部油区长6~长8储层天然裂缝特征研究”(ycsy2018ky-B-04)。

摘　　要：鄂尔多斯盆地西部上三叠统延长组致密油储层中发育大量裂缝。但是,目前缺少针对强非均质性陆相致密油储层裂缝的测井识别方法的系统研究。以西部油区延长组长6~长8地层为例,利用大量取心、常规及微电阻率成像测井资料,对致密油储层裂缝的测井评价方法进行了系统研究。研究结果表明,长6~长8地层致密砂岩中主要发育高角度及垂直构造剪切缝、张裂缝及层理缝。裂缝密度主要分布在0~0.2条/m,低幅度构造区裂缝发育程度相对较低。在构建常规测井裂缝模型过程中,首先对测井曲线进行预处理,并消除了泥质及凝灰质的不利影响。然后,在对各单一常规测井曲线的裂缝敏感性分析基础上,依次构建基于曲线变化率的裂缝表征参数模型、基于曲线分形维数的裂缝表征参数模型、基于微电极幅度差的裂缝表征参数模型及综合指数模型。综合指数模型实现了多常规测井信息融合及逐步剔除功能,能有效识别砂岩中的裂缝发育段,裂缝识别精度可达80%。根据裂缝方位分析确定了裂缝的形成与区域应力环境的耦合关系,砂体厚度与裂缝的发育程度具有一定负相关性。但对部分砂体而言,裂缝发育程度与单砂体厚度具有一定正相关关系,反映出这类砂岩可能位于应力相对集中的特殊构造部位。该研究可以为致密油甜点预测提供科学指导。A large number of core fractures are developed in the tight oil reservoirs of the Upper Triassic Yanchang formation in the western oil region of the Ordos basin.However,there is a lack of systematic research on log identification methods for fractures in tightly heterogeneous continental tight oil reservoirs.In this paper,taking Chang 6~Chang 8 of Yanchang formation in the western oil region as an example,we conducted a systematic study on the log evaluation methods of tight oil reservoir fractures,using a large amount of core,conventional logging,and micro-resistivity imaging logging data.The research results show that high-angle and vertical structural shear fractures,tension fractures and bedding fractures are mainly developed in the Chang 6~Chang 8 tight sandstone.The density of fractures is mainly distributed in the range of 0.2 strips/m.In the process of constructing the conventional logging fracture model,the logging curve is preprocessed,and the adverse effects of shale and tufface are eliminated.Then,based on the analysis of the fracture sensitivity of each single conventional logging curve,a fracture characterization parameter model based on the rate of change of the curve,a fracture characterization parameter model based on the fractal dimension of the curve,a fracture characterization model based on the amplitude difference of the microelectrode and a comprehensive index model are successively constructed.The comprehensive index model realizes the function of fusion and gradual elimination of multiple conventional logging information,and can effectively identify fracture development sections in sandstone.The accuracy of fracture identification can reach 80%.The results of fracture azimuth analysis show that the development azimuth of fractures in the target layer is mainly affected by the horizontal squeezing stress field in the Yanshanian and Himalayan periods.The thickness of the sand body has a certain negative correlation with the degree of fracture development.But for some sand bodies,the degree

关 键 词：测井评价 西部油区 延长组 致密油 裂缝 鄂尔多斯盆地 

分 类 号：P631.84[天文地球—地质矿产勘探]