Research on Modeling and Prediction of Shale-Gas Reservoir Geostress Field Based on Seismic Data

As an important kind of low porosity and low permeability reservoirs, the current development of shale gas relies on large-scale hydraulic fracturing to obtain commercial gas stream. Geostress, the key factor in hydraulic fracturing, will directly affect fracturing design and the final fracturing effects. Most current prediction methods of geostress focus on wellbores while the lateral distribution of geostress field cannot be well described. Seismic data own rich details in lateral directions. After years of study and development, the precision of geology interpretation and prestack inversion has been largely improved for shale-gas reservoirs in the Sichuan Basin, making it possible to predict geostress field based on seismic data and results. Therefore, in the paper, a geostress modeling and prediction method on the basis of seismic data is proposed. With well data, geostress tests, seismic interpretation and pre-stack inversion results of shale gas reservoirs in the Weiyuan shale block, a workflow of shale-gas geostress field prediction is built by using rock mechanics method and 3D grid modeling technique. The method which inherits the advantages of multiple sampling in seismic exploration can obtain continuous geostress profiles in both lateral and vertical direction. It can deliver geostress information before drilling, providing reference and guidance for the later hydraulic fracturing and development. The geological grid model built in the workflow also provides a model basis for the numerical simulation of hydraulic fracturing and production, enhancing the integration of exploration and production.