克拉苏构造带盐下深层断背斜储集层构造裂缝带分布规律

克拉苏构造带是塔里木盆地天然气重点勘探区域,主力含气层系为下白垩统巴什基奇克组,构造裂缝普遍发育,是低孔砂岩储集层高产稳产的关键因素。基于克拉苏构造带盐下深层断背斜储集层构造裂缝发育特征及裂缝带分布规律研究,探索了裂缝带组合与产能的关系,明确了储集层裂缝以未充填—半充填的高角度缝为主,多为张性或张剪性,具有规律性成带分布的特征,裂缝带宽度一般为10～40 m,裂缝带间距一般为10～50 m;根据储集层裂缝带成因及分布规律等差异特征,划分了储集层东西向裂缝带、南北向裂缝带和网状裂缝带3种成因裂缝带;根据储集层裂缝发育特征及裂缝带空间组合特征等差异性,储集层可划分为Ⅰ类高产区、Ⅱ类中高产区和Ⅲ类低产区。

Distribution of Tectonic Fissure Zones in Subsalt Deep Faulted-Anticline Reservoirs in Kelasu Tectonic Belt

Kelasu tectonic belt is the key area for natural gas exploration in the Tarim basin,and its main gas?bearing series are the Lower Cretaceous Bashijiqike formation where tectonic fissures are generally developed,which is considered as the key factor for the high and sta?ble deliverability of low?porosity sandstone reservoirs.Based on the study of the characteristics of tectonic fissure development and fissure zone distribution in the subsalt deep faulted?anticline reservoirs of Kelasu tectonic belt,the paper studies the relationship between the fis?sure zone combination and its deliverability,identifies that the reservoir fractures are dominated by unfilled-half?filled high?angle fractures which are mainly tensile fractures or tensile shear fractures and are characterized by zonal distribution with the fracture zone width and in?terval of 10~40 m and 10~50 m,respectively.According to the differences in genesis and distribution of fracture zones,3 types of reservoir fracture zones are classified,i.e.,E?W trending fracture zone,N?S trending fracture zone and netlike fracture zone.According to the charac?teristics of reservoir fracture development and fracture zone spatial combination,the reservoir can be divided into 3 kinds of regions,name?ly ClassⅠhigh?deliverability region,ClassⅡmedium-high deliverability region and ClassⅢlow?deliverability region.