May 3, 2024
Ali Ranjbar

Ali Ranjbar

Academic Rank: Assistant professor
Address:
Degree: Ph.D in Petrolium Engineering
Phone: 077
Faculty: Faculty of Petroleum, Gas and Petrochemical Engineering

Research

Title Estimation of shear wave velocity in an Iranian oil reservoir using machine learning methods
Type Article
Keywords
Shear wave velocityMachine learningDipole sonic imager (DSI)Multi-layer perceptronArtificial neural networkMulti-gene genetic programmingWireline logs
Journal JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
DOI https://doi.org/10.1016/j.petrol.2021.109841
Researchers Amin Izadpanahi (Second researcher) , Parirokh Ebrahimi (Third researcher) , Ali Ranjbar (Fourth researcher)

Abstract

Shear wave velocity is considered as one of the most important rock physical parameters which can be measured by dipole sonic imager (DSI) tool. This parameter is applied to evaluate porosity and permeability, rock mechanical parameters, lithology, fracture assessment, etc. On the other hand, this data is not available in all wells and hence, an accurate and reliable estimation of this parameter with the least uncertainty is of great importance in reservoir characterization. In this study, regression, multi-layer perceptron artificial neural network (MLP-ANN), adaptive neuro-fuzzy inference system (ANFIS) and multi-gene genetic programming (MGGP) methods are utilized to estimate the shear wave velocity using well log data. Also, the reported empirical correlations in the literature are also investigated in the studied field. The input data include depth, effective porosity, Vp, gamma ray logs (natural and spectral), neutron log, density log and caliper log from the Bangestan Group Formation in one of the fields in southwestern Iran. In this study, all the expressed methods are compared based on the best coefficient of determination (R2), root mean square error (RMSE), mean squared error (MSE), average absolute relative error (AARE), and average relative error (ARE). Among the used methods, MGGP was developed for using the useful features of this method including sensitivity analysis and correlation. Sensitivity analysis is performed on the input data using the MLP-ANN and MGGP method. Also, a correlation is suggested based on the MGGP method which is able to predict the shear wave velocity using the mentioned input parameters. The results show that the MLP-ANN method is more accurate, reliable and efficient compared to other methods studied in this paper. R2 for the train, validation, and test phase are 0.9973, 0.9901 and 0.9898, respectively. The results of sensitivity analysis imply that compressional wave velocity has the highest impact on the shear wave velocity