塔里木盆地顺西地区断裂特征及对奥陶系碳酸盐岩储层的影响

Characteristics of Faults and Their Influence on Ordovician Carbonate Reservoirs in Shunxi Area,Tarim Block

断裂不仅是良好的渗滤体,还为埋藏溶蚀、表生期岩溶提供了通道,断裂也是奥陶系碳酸盐岩储层最重要的控制因素之一。综合应用地球物理、单井资料对塔里木盆地顺西地区断裂类型及特征进行分析,建立了断裂与储层之间的相关性。顺西地区断裂分为逆冲断裂和走滑断裂2种类型。逆冲断裂主要为塔中Ⅰ号断裂,为盖层滑脱型逆冲断裂,形成于加里东中期Ⅰ幕,呈北西-南东向展布,自西向东可分为5段,其活动性自西向东逐渐增强。走滑断裂主要为顺西1号断裂,共识别出花状构造、直立线性构造、羽状构造、拉分地堑构造、马尾构造等5种构造样式;其在良里塔格组顶界面表现为数个活动强段和变形弱段交替出现的分布特征;走滑断裂形成于志留纪末期,继续发育于泥盆纪,结束于石炭纪-二叠纪。距离走滑断裂羽状构造、拉分地堑构造部位近的区域张性裂缝裂发育,裂缝线密度高,为储层最有利发育区。

Fault is not only a good percolation mass,but also provides a channel for buried dissolution and karst.It is one of the most important controlling factors of Ordovician carbonate reservoir.Based on the geophysical and single well data,the fault types and the characteristics of each type in Shunxi area are analyzed,and the correlation between faults and Ordovician carbonate reservoirs is established.The faults in Shunxi area can be divided into two types:thrust fault and strike slip fault.The former is mainly Tazhong No.1 fault,which is a slippage type of overburden thrust fault,and was formed in the middle Caledonian episode I and distributed in NW-SE direction.From west to east,it can be divided into five segments,and its activity gradually increases from west to east.The strike-slip fault is mainly Shunxi No.1 fault,which can be divided into flower structure,vertical linear structure,pinnate structure,pull-apart graben and horsetail-type structure.The top interface of Lianglitage Formation shows the distribution characteristics of several active strong segments and weak deformation segments.The strike-slip fault was formed at the end of Silurian,continued to develop in Devonian and ended in Carboniferous-Permian.The area near strike-slip fault pinnate structure and pull-apart graben structure is developed with high fracture linear density,which is the most favorable area for carbonate reservoir.