Abstract:

The tight clastic rock gas reservoirs in the second Member of the Upper Triassic Xujiahe Formation of deep formation in Western Sichuan is characterized by strong inhomogeneity. The high-permeability block which is combination of fractured network and relatively high quality reservoir distribution predicted,  is the key technology  for  gaining  high and stable yields. Based on observing surface outcrops, drilling data of statistical analysis and seismic profiles, the genetic mechanisms of the high-permeability block  are analyzed. The  fractured and high-permeability zones are well developed in the facies-varied zone，the break zone of bed thickness，the excellent reservoir block，the strong structural deformation zone and the area near the fault. With contrastive analysis of the characteristic of high efficiency reservoir permeable area logging, wave impedance and seismic response, model forward, etc, the identifying patterns for dim spots of littery reflection and weak reflection are built, the distribution of high-permeability block is predicted, and the geologic origin of the high-permeability block is discussed by the poststack absorbs processing, the body image pixel technology and the three-dimensional (3D) visualization technology. The predicted results are verified by drilling.

Key words: genetic mechanism, seismic reservoir prediction, high-permeability block, fractured gas reservoir, deep formation in Western Sichuan