深层裂缝性致密碎屑岩气藏高效储渗区识别——以川西新场气田上三叠统须家河组气藏为例

Identification of high efficiency payzones with high permeability in deep fractured tight detrital reservoirs:A case study of gas reservoirs in the Upper Triassic Xujiahe Formation of Xinchang gas field in western Sichuan Basin

四川盆地西部深层上三叠统须家河组须二段致密碎屑岩气藏非均质性极强,准确预测规模裂缝网络与相对优质储层叠加形成的高效储渗区分布规律是勘探开发钻井获得高产稳产井的技术关键。以三维三分量地震勘探资料为基础,通过高效储渗区储层测井及波阻抗特征、地震响应特征对比分析、模型正演验证等方法,建立"杂乱弱反射"地震暗点高效储渗区识别模式,划分出PP波/PS波"单弱"及"双弱"2种暗点类型,解剖了其地质及地球物理成因机理,提出"双弱"模式为最优类型。利用对杂乱弱反射的吸收增强处理及像素成像暗点可视化刻画等技术手段,预测出了高效储渗区。

The tight detrital gas reservoirs in the second member of the Upper Triassic Xujiahe Formation(T3x2)in western Sichuan Basin are featured by strong heterogeneity.Sizable fracture networks,together with relatively quality reservoirs,result in high efficiency payzones with high permeability,is critical to the success of exploration and development in drilling.Based on 3D 3C seismic data,we performed correlation of logging and wave impedance features with seismic responses,and forward modeling.We built up a model to identify high efficiency payzones with high permeability by using dim spots of 'weak chaotic reflection',and then identified two types of dim spots,i.e.'single weak' and 'double weak' of PP-and PS-wave.Based on an analysis of their geological and geophysical genetic mechanisms,the 'double weak' mode is believed to be the optimal.High efficiency payzones with high permeability are identified through absorption-enhancing processing of the weak chaotic reflection and visualization of pixel image.