新疆小拐地区二叠系佳木河组裂缝分布规律探讨

STUDY ON THE FRACTURE DISTRIBUTION AND NUMERICAL SIMULATION OF JIANUHE FORMATION OF PERMIAN IN XIAOGUAI OILFIELD

通过对新疆小拐地区二叠系佳木河组,17口井的岩心观测、测井解释裂缝以及其中14口井200余个薄片鉴定分析,结合区域构造演化分析,认为该区裂缝主要为区域性的构造缝,为多次地质作用叠加改造的结果,裂缝倾角主要以≥75°的直立缝为主,所占比例超过75%,总体特征表现为裂缝延伸较长(大于20cm),裂缝宽度主要集中在0.1mm～1mm之间,所占比例达60%以上,裂缝密度多数在0.6条/米～0.8条/米,未充填裂缝所占比例为90.5%,占绝对优势;工区裂缝主要受岩性和层厚的控制,裂缝主要发育在细砾岩、砂砾岩和薄层含砾砂岩中,根据研究区的实际情况,综合利用地质认识、古构造应力反演、相干数据体处理对裂缝分布规律进行再认识,预测裂缝发育带。最终对这3种方法进行权重分析及裂缝的综合评价表明:裂缝主要发育在G102-G5-G105、CP3-G103、G9井区、G13及G3井、C502-C67-C501及其南部,总体上呈片状或扇形展布。

Original understanding of the fractures on the Jiamuhe Formation of Permian in Xl-aoguai area can no longer meet the needs of the exploration and development. Based on the core observation and fracture parameter by log of 17 wells,more than 200 thin section identification of 14 wells,and the regional tectonic evolution,it is indicated that the fractures are regional structur-al fractures caused by a number of geological superimposed. In fact, the fractures are widely devel-oped standing seam,with the dips above 75°. 75 percent fractures have 20 cm long and 0.1 mm-1 mm wide. Fracture density ranges from 0.6 - 0.8 strip per meter. Among them, the unfilled fractures account for 90.5 percent. It is showed that the fractures are mainly affected by influence of lithology and bedding thickness. Fractures mainly occur in microconglomerate, glutenite and thin-bedded pebbly sandstone. According to the actual situation of the study area, comprehensive utilization of geological knowledge, tectonic stress inversion, coherence cube processing are used to recognize the distribution of fractures and numerical simulation is used to predict the fracture zone. It has showed that the fractures are mainly developed in G102-GS-G105, CP3-G103 ,G9, G13 and G3,C502-C67-C501. In general,the fractures distribute like flaky or fan-shaped.