四川盆地泸州北区五峰组—龙马溪组深层 页岩气储层地应力地震预测技术. (Chinese)

Stress seismic prediction technology of deep shale gas reservoir of Wufeng-Longmaxi formations in North Luzhou District， Sichuan Basin. (English)

The deep shale gas reservoirs in the north Luzhou District of the Sichuan Basin are affected by multiple phases of tectonic movements, and are characterized by complex tectonic conditions, rapid changes in in-situ stress, which leading to the difficulties of in-situ stress prediction. A specific in-situ stress seismic approach based on pre-stack azimuthal anisotropic inversion is proposed. Pre-stack AVAZ inversion approach applied azimuthal anisotropy AVA equation under Bayes theory framework. The elastic and anisotropic parameters of the shale gas reservoir are inverted from pre-stack Offset Vector Tile (OVT) gather. Meanwhile, a formula Differential Horizontal Stress Ratio (DHSR) based on the fracture density and Poisson's ratio representation is derived, which is utilized to estimate the DHSR of shale gas reservoir. Wufeng Formation-Long 1 submember and favorable areas for shale gas exploration and development were delineated. This provides reliable geophysical evidence for reserve evaluation, well trajectory design, and reservoir stimulation in the study area. Using this method, deep shale gas in the Wufeng Formation–Long11 subsection of the northern Luzhou area in the Sichuan Basin was predicted by DHSR, and favorable areas for shale gas exploration and development were delineated. This provides a reliable geophysical basis for the reservoir evaluation, well trajectories designment, and reservoir modification. [ABSTRACT FROM AUTHOR]

四川盆地泸州北区深层页岩储层受多期构造运动的影响, 构造条件复杂、地应力变化快的特 征, 导致其预测难度大。鉴于此, 针对性地提出了一种基于叠前各向异性反演的地应力地震预测 技术, 在贝叶斯理论框架下, 利用各向异性 AVA (Amplitude Versus Angle, 振幅随入射角变化)方 程构建叠前 AVAZ (Amplitude Versus Azimuth, 振幅随方位角变化)反演方法, 从叠前偏移距矢量 片 (Offset Vector Tile, OVT)道集出发, 反演获得页岩储层的弹性参数与各向异性参数; 同时, 推 导了基于裂缝密度和泊松比表示的水平应力差异比 (Differential Horizontal Stress Ratio, DHSR) 计算公式, 用于估算储层的 DHSR。利用该方法对四川盆地泸州北区五峰组—龙一 1亚段深层页岩 气开展 DHSR 预测, 并划定了页岩气勘探开发的有利区, 为研究区的评价部署、井轨迹设计及储层 改造等提供可靠的地球物理依据。 [ABSTRACT FROM AUTHOR]

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