Systematic prediction of the gas content, fractures, and brittleness in fractured shale reservoirs with TTI medium  

作　　者：Yun Zhao Xiao-Tao Wen Chen-Long Li Yang Liu Chun-Lan Xie 

机构地区：[1]Key Laboratory of Earth Exploration and Information Techniques,Ministry of Education,Chengdu University of Technology,Chengdu,610059,Sichuan China [2]College of Geophysics,Chengdu University of Technology,Chengdu,610059,Sichuan China

出　　处：《Petroleum Science》2024年第5期3202-3221,共20页石油科学（英文版）

基　　金：financially supported by the Sichuan Science and Technology Program (Grant No. 2023ZYD0158);the National Natural Science Foundation of China (Grant Nos. 42304147 and 42304076)。

摘　　要：The main objective is to optimize the development of shale gas-rich areas by predicting seismic sweet spot parameters in shale reservoirs. We systematically assessed the fracture development, fracture gas content, and rock brittleness in fractured gas-bearing shale reservoirs. To better characterize gas-bearing shale reservoirs with tilted fractures, we optimized the petrophysical modeling based on the equivalent medium theory. Based on the advantages of shale petrophysical modeling, we not only considered the brittle mineral fraction but also the combined effect of shale porosity, gas saturation, and total organic carbon(TOC) when optimizing the brittleness index. Due to fractures generally functioning as essential channels for fluid storage and movement, fracture density and fracture fluid identification factors are critical geophysical parameters for fractured reservoir prediction. We defined a new fracture gas indication factor(GFI) to detect fracture-effective gas content. A new linear PP-wave reflection coefficient equation for a tilted transversely isotropic(TTI) medium was rederived, realizing the direct prediction of anisotropic fracture parameters and the isotropic elasticity parameters from offset vector tile(OVT)-domain seismic data. Synthetic seismic data experiments demonstrated that the inversion algorithm based on the L_P quasinorm sparsity constraint and the split-component inversion strategy exhibits high stability and noise resistance. Finally, we applied our new prediction method to evaluate fractured gas-bearing shale reservoirs in the Sichuan Basin of China, demonstrating its effectiveness.

关 键 词：Petrophysical modeling Brittleness index Fracture gas indication factor(GFI) Tilted transversely isotropic(TTI) Fracture density 

分 类 号：TE311[石油与天然气工程—油气田开发工程]