巴喀油田西山窑组储层裂缝特征及对低渗透油藏开发的影响

Characteristics of the Fract ures of Xishanyao Formation and Their Influence on Waterflooding in Baka Oilfield

通过对巴喀油田西山窑组储层精细研究,裂缝是低孔特低渗性储集砂岩的主要渗流通道,裂缝的复杂分布特征严重影响了巴喀油田的开发效果,结合区域构造背景和大地构造主应力方向,选取了岩心、薄片和成像测井等资料相对较完整的井,分析了研究区内裂缝形成的主要控制因素以及裂缝发育所形成的重点表征特征。研究表明该区砂岩储层中的裂缝主要为挤压应力下形成的剪切裂缝,其倾角多大于30°,走向则主要为NWW向和NNE向,另外局部地区还有NW向和NE向两组次要裂缝发育。受现今地应力影响,NWW和NW向裂缝开度大,为主要的渗流方向。受岩性、构造部位、层厚和沉积微相等不同的影响,裂缝的发育程度和发育特征差异很大。应根据裂缝的主渗流方向、砂体展布等特征来完善注采系统,进而改善开发效果。

Through the detailed study of the Xishanyao Formation reservoir in the Baka Oilfield,the fracture is the main seepage channel of low porosity and ultra-low permeability reservoir sandstone,and the complex distribution characteristics of the fracture have seriously affected the development effect of the Baka Oilfield.In combination with the regional tectonic background and the main stress direction of the ge-otectonic structure,the well with relatively complete core,thin section and imaging logging data was se-lected,The main control factors of fracture formation and the key characteristics of fracture development n the study area are analyzed.The study shows that the fractures in the sandstone reservoir in this area are mainly shear fractures formed under compressive stress,with the dip angle of more than 70,and the strike is mainly NWW and NNE.In addition,there are two groups of secondary fractures in NW and NE in local areas.Influenced by the current geostress,NWW and NW fractures have large openings,which are the main seepage directions.Affected by different lithology,structural location,layer thickness and sedi-mentary micro-equivalence,the development degree and characteristics of fractures vary greatly.The injec-tion-production system should be improved according to the main seepage direction of fractures and the dis-tribution of sand bodies,so as to improve the development effect.