鄂尔多斯盆地东南地区延长组长6_(3)-长7_(1)低孔低渗储层裂缝特征及其影响因素

Fracture Characteristics and Influencing Factors in Chang 6_(3)-Chang 7_(1)Low-porosity and Low-permeability Reservoir of Yanchang Formation in Southeastern Ordos Basin

研究区长6_(3)-长7_(1)低孔低渗储层天然裂缝发育类型多、成因复杂,为了厘清其裂缝发育特征及其影响因素,通过综合运用野外露头调查、岩心观察及成像测井裂缝识别等方法,系统分析了研究区长6_(3)-长7_(1)裂缝特征及其影响因素。结果表明:研究区长7_(1)较长6_(3)裂缝更发育,裂缝主要发育在细砂岩中,产状以垂直缝和高角度斜交缝为主,多数为未充填缝,裂缝的发育主要受区域应力值、地层岩性、岩石物性、岩层厚度及力学结构面影响。研究成果为该地区低孔低渗储层注水驱油和人工压裂的部署方案提供理论依据与支持。

In order to clarify the characteristics of fracture development and its influencing factors,there are many types and complex causes of natural fractures in the low-porosity and low-permeability reservoirs of Chang 6_(3)-Chang 7_(1)in the study area.By means of outcrop investigation,core observation and fracture identification by imaging logging,the characteristics and influencing factors of fractures in the study area from Chang 6_(3)-Chang 7_(1)were systematically analyzed.The results show that the fractures of Chang 7_(1)are more developed than those of Chang 6_(3)in the study area.The fractures are mainly developed in fine sandstone,and their occurrence is dominated by vertical fractures and high Angle oblique fractures,most of which are unfilled fractures.The development of fractures is mainly affected by regional stress value,formation lithology,petrophysical property,rock layer thickness and mechanical structural plane.The research results provide theoretical basis and support for the deployment plan of water injection for oil recovery and artificial fracturing in low porosity and low permeability reservoirs in the study area.