下寺湾地区延长组长8储层属典型的低孔、低渗砂岩储层。裂缝可作为低渗透储层的有效储集空间和主要渗流通道,对油气聚集成藏及开发具有重要作用。裂缝特征及识别是该区储层评价研究的重要内容。基于下寺湾地区的区域地质、测井、钻井和岩心等资料,从构造应力场研究、薄片观察、常规测井识别等方面对该区长8储层的裂缝特征进行了分析。结果表明：通过古构造应力场与现代构造应力场的对比,确定了研究区裂缝发育的优势方位为北偏东70°;通过岩心薄片分析,认为研究区长8储层微裂缝发育,连通性较好;应用＂深侧向电阻率与声波时差交会图＂与＂常规测井裂缝响应特征＂相结合的裂缝识别方法,对该区单井裂缝进行识别,认为常规测井资料识别的裂缝多发育在泥岩段。%Chang 8 reservoir of Yanchang Formation in Xiasiwan area of Ordos Basin is a typical low porosity and low permeability sandstone reservoir.The fractures have a significant impact on hydrocarbon accumulation and the oilfield development effect as the fractures can be as the effective space and the main seepage channel of low permeability reservoir.Therefore,the characteristics and the identifications of the fracture are the key research work to the evaluation of the reservoir in this area.Based on regional geology,well logging,well drilling and core data in Xiasiwan area,fracture characteristics were analyzed by the study of tectonic stress field,slices and conventional logging analysis.Through the comparison between the palaeotectonic stress field and the modern tectonic stress field,the favorable distribution position of the fractures is analyzed and the main orientation affected by regional tectonic movement is NE 70°,which can provide a strong basis for suitable arrangement of well patterns.The data of rock slices indicate that micro-fractures are well developed and have better connectivity.By combining with the intersection identification method of deep-probe resistivity and acoustic time and the response characteristics of conventional logging for fractures,the single well fractures can be identified,and it is concluded that conventional logging data is more inclined to identify the fractures developed in mudstone.
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