Quantitative Prediction Of Shale Gas Reservoir Parameters Based On Rock Physics Template

With the increasing tension in oil and gas resources in the world,shale gas becomes an important resource.Its exploration and development has arise general concern and high recognition widespread.Due to the complex geological conditions,apparent anisotropic characteristics,various pores and fluids of shale formation,the exploration and development of shale gas is of great difficulty.Therefore,it is very important and valuable for effectively identification and exploration of shale gas to research an appropriate geophysical method to predict reservoirs and quantitative interpret reservoir parameters.Research on the seismic rock physics theory is the basis of reservoir quantitative prediction by seismic data.So in this paper,firstly we introduce the classical isotropic and anisotropic seismic rock physics theory.Using them as bases and according to the anisotropy,mineral,porosity and fluid characteristics of shale formation,we put forward the build process and build the shale rock physics equivalent model.The model is applied to the S-wave velocity prediction in actual shale work area.The results show that shale rock physical equivalent model has high prediction accuracy,and its applicability is verified.Then based on this model,we analyse the distribution characteristics of brittle reservoir and horizontal closure stress of shale formation,put forward the suitable indicated parameter of rock brittleness and prediction method of horizontal closure stress based on anisotropic assumption.Synthesizing the two sides,we accurately predict the effective reservoirs which are easy to fracturing.Finally,using the rock physics model as a basis,we optimize sensitive parameters with the change of porosity and gas saturation as the abscissa and ordinate of the rock physics template.By analyzing of minerals,porosity and fluid characteristics of the effective reservoirs and non-reservoirs in the shale gas wells,we determine the value of constants and the range of the variable parameters in the rock physics template.Then we establish the shale rock physics quantitative interpretation template and correct it by core data and logging data of our research work area.The template and extracted parameters from seismic inversion are combined to decide the reservoir distribution and quantitatively interpret the porosity and gas saturation within the range of reservoir.The example analyses show that the porosity and gas saturation getting by our shale rock physics template are basically identical with the actual gas production and porosity.And the reliability and applicability in shale reservoir porosity and gas saturation quantitative interpretation of our rock physics template are verified.