Interactive Forward and Inversion Scheme‐Based Anisotropic Correction for Shale Gas Horizontal Well Sonic Logs and Its Application

Abstract

Well logging interpretation and evaluation of reservoirs in horizontal wells plays an important role in shale gas exploration and development. The accuracy of the interpreted petrophysical parameters is directly affected by well logging curves. This study focuses on a horizontal well targeting deep shale gas layers in the Luzhou block, Southern Sichuan Basin. It employs an interactive forward and inversion scheme to precisely reconstruct the borehole trajectory using a comprehensive dataset encompassing well logs, mud logs, and seismic data. The research introduces a method for anisotropic correction of sonic log, crucial for calculating reservoir parameters, and assess payzone targeting in the horizontal well. The research results show that the interactive forward and inverse simulation method can achieve the recovery of horizontal well borehole trajectory and finely delineate the sublayers, improving the evaluation accuracy of platinum target drilling encounter ratio by over 6%. Numerically simulated acoustic wave can be used to carry out the anisotropy correction of acoustic wave in horizontal wells and calculate reservoir parameters, reducing the relative error in computed porosity to 1.72%. The comprehensive logging evaluation results from both geological and engineering aspects provide the data basis for planning the fracturing program of the shale gas horizontal well. This research has established a new method and idea for well logging evaluation in shale gas horizontal wells, marking a significant step toward integrating geological and engineering aspects in shale gas exploration.