WANG Ziqi, WU Chaorong, HUANG Kaixing, SUN Zhengxing, HAO Yuexiang, LI Yong
Online available: 2025-03-05
The total organic carbon(TOC)content is an important evaluation index for shale gas exploration and development. Logging data can efficiently assess TOC,but it cannot be used for TOC prediction in inter well areas. The TOC -sensitive factors extracted from seismic data can achieve three -dimensional(3D)prediction. However,due to the thin thickness and strong heterogeneity of shale reservoirs,it is difficult to achieve the required resolution by relying solely on seismic data. Therefore,it is necessary to comprehensively use multiple data sources to improve the accuracy of TOC assessment. For this purpose,a high -precision quantitative prediction method for shale TOC based on a convolutional neural network(CNN)is proposed. Firstly,the correlation analysis between the measured TOC data of the core from drilling and multiple logging characteristic curves is conducted on the Longmaxi Formation shale in southern Sichuan,and the most representative and sensitive features are selected. Secondly,based on the identified sensitive parameters,a CNN prediction model is constructed. The measured TOC samples and the training samples constructed by sensitive logging parameters are divided into datasets at a ratio of 7:3 for model training and validation. Finally,the high-resolution sensitive parameter inversion results obtained by simulation of seismic waveform indication are used as the feature input for 3D TOC content prediction. The sensitive parameters are rearranged,reorganized,and then input into the CNN model to achieve 3D TOC content prediction. The research results show that CNN has more advantages than multiple regression and back propagation(BP)neural networks in fitting the nonlinear relationship between TOC content and sensitive parameters. The average absolute error and root mean square error are both less than 0. 6 between the predicted TOC data and the measured values from drilling. The prediction results are consistent with the actual situation. This method has high accuracy and obvious advantages in 3D TOC content prediction of thin shale reservoirs.