石油物探2025，Vol.64Issue(2)：340-352,13.DOI:10.12431/issn.1000-1441.2023.0413
TTI型页岩气储层脆性指数和裂缝参数分级反演方法
Hierarchical inversion of brittleness indicator and fracture parameters for shale gas reservoirs with tilted transverse isotropy
摘要
Abstract
Subsurface formations with aligned dipping fractures can be equivalent to the media with tilted transverse isotropy(TTI).For TTI-type organic-rich shale gas reservoirs,the Young's modulus is not a sensitive brittleness indicator as a low value may emerge at a high degree of brittleness.Therefore,a hierarchical seismic inversion method is proposed to directly predict the brittleness and fracture parameters of TTI-type organic-rich shale gas reservoirs.We derive a linearized P-wave reflection coefficient equation for TTI media in terms of a new brittleness indicator formulated as the function of the Young's modulus and Lamé constant(λ),fracture density and fracture dip.The reflection coefficient equation is rewritten in the form of the Fourier series to separate fracture information from background matrix information.Based on the Bayesian framework,the hierarchical inversion method is established to predict brittleness indicator and fracture parameters.The process is composed of three steps.Firstly,we utilize the discrete Fourier series to decouple the isotropic(zero-order)and anisotropic(second-order)components of azimuthal seismic data.Secondly,we invert fracture density and fracture dip from the second-order component of azimuthal data.Thirdly,the brittleness indicator can be estimated using the zero-order component.The model test and practical application indicate the robustness of the method and credible prediction of high-quality brittle reservoirs.关键词
脆性指数/裂缝密度和倾角/TTI介质/纵波反射系数/傅里叶级数Key words
brittleness indicator/fracture density and fracture dip/TTI medium/PP-wave reflectivity/Fourier series分类
地质学引用本文复制引用
谭媛媛,张广智,马正乾,郝洪鉴,韩钊..TTI型页岩气储层脆性指数和裂缝参数分级反演方法[J].石油物探,2025,64(2):340-352,13.基金项目
国家自然科学基金项目(42074136,U23B6010)和中国石油天然气股份有限公司项目"复杂气藏岩石物理机理及模型构建研究"(2022A-080)共同资助. This research is financially supported by the National Natural Science Foundation of China(Grant Nos.42074136,U23B6010)and the Project of the PetroChina Company Limited(Grant No.2022A-080). （42074136,U23B6010）
