松辽盆地梨树断陷营城组储集层裂缝特征及形成演化

Formation and Evolution of Reservoir Fractures in Yingcheng Formation of Lishu Fault Depression,Songliao Basin

松辽盆地梨树断陷营城组为典型的低孔低渗裂缝型砂岩储集层,裂缝的发育情况对油气勘探开发有重要意义。利用区域地质、岩心、薄片、测井、物探及分析化验等资料,对梨树断陷营城组储集层裂缝特征及形成演化开展综合研究。结果表明,营城组储集层裂缝比较发育,以构造成因的剪切缝和扭张缝为主;裂缝长度为0~15 cm,裂缝规模以小、微型裂缝为主,裂缝密度普遍小于0. 2条/m;裂缝主要发育在细砂岩中,充填物主要为方解石;裂缝走向以近南北向、北东向方位为主;梨树断陷构造发育主要包括断陷和拗陷两个阶段,形成了4期断裂及裂缝系统,营城组末期、登娄库组末期以及嫩江组末期是主要的成缝期,断裂对油气的运移、聚集以及分布有重要的作用。

The Yingcheng Formation in the Lishu fault depression of the Songliao Basin is a typical low porosity and low permeability sandstone reservoir. The development of fractures is of great significance for oil and gas exploration and development in such reservoir. The characteristics and formation evolution of reservoir fractures in Yingcheng Formation are addressed by comprehensive studies of regional geology,petrography,logging,geophysical prospecting and laboratory analysis.The results show that the fractures in Yingcheng Formation are well developed. They are mainly shear and shear-tension fractures. The fractures are generally small and micro fractures,with length of 0 to 15 cm and density less than 0. 2 m-1. They are mainly developed in fine sandstone,which is filled with calcite. The strike of the fractures are mainly N-S and NE. The structural development of the Lishu fault depression mainly includes two stages: fault depression and depression,forming four stages of fault and fracture systems. The main formation stages are the late stage of the Yingcheng,Denglouku and Nenjiang Formations. Faults play an important role in the migration,accumulation and distribution of oil and gas.