Research On Seismic Rock Physics Modeling For Shale Gas Reservoir

The exploration and development of shale gas has been taken seriously,because it is very important kind of unconventional hydrocarbon energy,with large reserves and long mining cycle characteristics.Unlike conventional oil and gas reservoirs,shale gas reservoir has low porosity and permeability,high organic content,non-uniform distribution of pore fluids and anisotropic characteristics,which are needed for shale gas reservoir model.Rock physics modeling needs to be under the constraint of the measured data,which is helpful to improve the accuracy of the model calculation and effectively detect the applicability of the model.In this paper,the disturbance model and optimization process of simulated annealing algorithm are improved,to reduce the cycle number and the dependence on disturbance model,which has better effect after the example application and analysis.The compactness is the commen characteristic among many unconventional reservoirs such as shale gas reservoir,and the compactness characteristic bas been discussed and analyzed in this paper,by comparingtwo kinds of rock physics models,the effective medium models(DEM model,SC model and KT model)and the poroelastic model(Gassmann model).By comparison,the Gassmann model shows its inapplicability for shear-wave velocity estimation of tight sand reservoir under the guidance and constraint of logging data.In order to get more accuracy elastic moduli and velocities,the S-S model is proposed,which takes both pore shapes(soft pore and stiff pore)and solid grain shapes(soft grain and stiff grain)into consideration.Based on the characters of shale gas reservoir,a new shale gas rock physics model is established,and the influences on anisotropic elastic parameters and AVO characteristics caused by physical property parameters are analyzed.Because of the complexity of shale gas reservoir,it is difficult to establish a common model for all shale gas reservoirs,and the research on shale gas modeling in this paper is need to further discuss and verify,in order to find out new shale gas reservoir rock physicstheory and method.