Construction And Application Of Effective Model Of Tight Sandstone Based On Rock Physics Theory

With the development of oil and gas exploration,unconventional tight sandstone oil and gas has become a new field of oil and gas exploration.To study the characteristics of seismic wave propagation in water saturated rocks or saturated rocks containing hydrocarbon,it is necessary to estimate the difference of the physical properties between the saturated state and the saturated state.Through the empirical formula between rock properties and elastic constants and theoretical relations,including mineral medium,porosity,rock stress and pore pressure,pore fluid type and saturation and anisotropy parameters of rock shear wave velocity and attenuation effects of such elastic parameters.These studies play an important role in seismic forward modeling and interpretation of inversion results.Through the tight sandstone reservoir diagenesis and tectonic transformation of the role of the complex in the long geological history,the general performance of tight lithology,pore and fine throat,small pore throat,poor connectivity and non-characteristics of strong heterogeneity.Due to these characteristics,the conventional sandstone petrophysical model is not applicable.In this paper,based on the analysis of the basic characteristics of the tight sandstone,the physical model of the complex tight sandstone reservoir is established under different assumptions.Then,in order to obtain a suitable criterion,the influence of the parameters on the elastic parameters of the saturated rock is discussed.The velocity and elastic parameters of the longitudinal and transverse waves are the important guarantee for reservoir evaluation and fluid identification.In the absence of the data of the velocity log,the elastic parameters of rock can be calculated by using the rock physics model.With the uncertainty of input parameters in the process,in order to solve this problem on the basis of conventional logging data,this paper proposes to use comprehensive logging information,determine the feasible domain of the model parameter inversion in constraint and improves the accuracy of the input parameters,reduces the prediction error of elastic parameters.At the same time,because the rock is affected by lithology,thickness,structural stress and other factors,the fracture parameters have a great influence on the results of the final elastic parameters.This paper presents a qualitative description of the fractures by conventional logging data,and improves the calculation accuracy of the elastic parameters.