Research On Seismic Methods For Predicting In-situ Stress In Bonan Area

The In-situ stress is influenced by multi-factors such as the gravitational loading of layer,tectonic stress as well as pore fluid pressure.The complexity increases the uncertainty in stress prediction methodology based on indirect parameter estimation,calculation error is significantly high.Currently,the lack of quantitative characterization makes it impossible to reveal the relevance between the seismic reflection data and in-situ stress.This study conducted a comprehensive research on in-situ stress prediction based on seismic data.We developed the feasibility of using seismic data to predict the stress field in Bonan region.In this study,stress field calculation model is built from well logging data.Conventional modelling combining with data set from Bonan region are considered during the model establishment,linear regression fitting is used to build the feasible stress calculation model in Bonan region.The accuracy of this methodology is tested by well logging data.Meanwhile,the effect of depth to stress prediction is considered during the process.After the depth correction to original well logging data,the effect of depth is defused from the modified stress model.The stress field calculated from these two models are validated by well logging data,the comparison results show the modified model which removed the depth effect more accurately predict the stress field variation in horizontal direction.Through the post-stack acoustic impedance inversion of partial angle stack data,3D P and S wave velocity volume as well as density volume are used to calculate 3D volume of young's modulus,bulk modulus,shear modulus and poisson ratio based on the relationships between rock properties.Combining with the modified model which the depth effect has been removed,the 3D stress field volume is calculated.Based on this methodology,the inclination,curvature and azimuth properties are extracted from 3D seismic data.The relationship between structural characteristics and in-situ stress are analyzed,the quantitative relationship between seismic data and in-situ stress provide essential information for further researches on reservoir characterization and oil development.