页岩气藏水平测井裂缝识别及声学成像研究

随着中国西南地区页岩气水平井钻探与开发取得重要进展,页岩气藏水平井测井资料的处理与解释变得尤为重要。对四川焦石坝页岩气水平井的声波测井数据进行处理,分析页岩地层水平井井孔声场及远探测声场的传播特征,旨在对页岩气藏中的裂缝进行识别和评价,为地震波方位各向异性的成因提供佐证。利用四分量偶极声波测井数据进行横波各向异性处理,分别获得水平偏振(SH)和垂直偏振(SV)的横波数据及波速。在此基础上采用横波远探测技术进行井外反射体的成像处理。处理结果表明该井外地层存在与井斜交的垂直裂缝体系,与该地区的构造形态有关,该裂缝体系的存在与该井区页岩气的高产密切相关。处理结果为页岩气水平井声学测井数据提供了有效的处理方法和较好的应用前景。

Acoustic Characterization and Imaging of Shale Gas Fractures in Horizontal Wells: Field Case Study in the Sichuan Basin of Southwest China

Fracture identification and characterization are of fundamental importance to the exploration and production of unconventional shale gas reservoirs.This paper presents a case study using borehole acoustic technology for fracture characterization and imaging in a horizontal well drilled through shale gas reservoir.The technology includes shear-wave anisotropy measurement and reflection imaging using the four-component (4C) cross-dipole logging data along the well.The anisotropy measurement obtains,respectively,the horizontally and vertically polarized SH and SV waves and their velocities from the 4C data.Reflection imaging using the SH and SV waves and their velocities determines the orientation of a formation reflector around the well.Application of the technology to a high-production shale gas reservoir in the Sichuan basin of Southwest China has successfully delineated vertical fracture sets crossing the horizontal well,suggesting that the presence of the fractures is related to the high gas production of the well.