Experimental Study On The Correlation Between Permeability And Elasticity Of Tight Sandstone

Compared with tight sandstone reservoirs with high porosity,high permeability and simple pore structure,compact sandstone reservoirs are characterized by complex pore structure,strong heterogeneity of permeability Coefficient and complex influence of elastic parameters.According to relevant researches at home and abroad,it is found that the microscopic pore structure plays an important role in the changes of permeability and acoustic velocity under pressure,but there is a lack of research on the correlation between physical and elastic parameters for tight sandstones.Therefore,it is convenient for quantitative analysis of tight sandstone reservoir characteristics by developing the laboratory measurement of relevant parameters,studying the internal relationship between physical parameters and elastic parameters,and establishing the permeability and elastic rock physics model based on tight sandstone characteristics.First of all,standard cores are prepared,and the porosity and permeability under different pressures were measured by the measurement platform of the porosity and permeability.The experimental results show that the micro-structure takes an active part in porosity,permeability and acoustic velocity.The porosity and permeability decrease exponentially and then in linear form with the increase of pressure.Furthermore,pore structure is the main factor affecting porosity and permeability and the soft pores begin to close gradually with the action of small pressure.In this way,the hard porosity is the main factor that affects the porosity and permeability.The acoustic velocity under different pressure,different temperature,dry and saturated conditions was measured by a multi-function core analysis system.Thus,the longitudinal wave velocity and the shear wave velocity show a trapezoidal form with an exponential increase first and then a linear increase with the pressure increase.The acoustic velocity of tight sandstone in saturated state increases with pressure compared with that in dry condition,and the increasing trend of acoustic velocity becomes gentler.Additionally,the sonic velocity is higher in the saturated state than in the dry state.In water-saturated state,the acoustic velocity of rock becomes a nearly linear decrease with the increase of temperature,and the increase of temperature will affect the rock modulus,resulting in the decrease of acoustic velocity.The porosity,permeability and Acoustic Velocity of the Compact sandstone core have the same form,and the main influence factors of the physical and elastic parameters of the compact sandstone are found by the experiments.Secondly,based on the experimental results of physical and elastic parameters under different pressures and the correlation model between permeability and Elasticity of tight sandstone with double porosity,a petrophysical model for tight sandstone is constructed,the relationship between permeability and elastic parameters is established by the two-hole theory.The Correlation Coefficient of porosity is fitted by the experimental data,and the improved correlation model between permeability and elasticity of tight sandstone has a good fitting result.This study provides a clear theoretical support for the Quantitative analysis between permeability and elastic parameters of tight sandstone.