Comparison and Study over the Biot Coefficients Test Methods in Medium Porosity and Medium Permeability Sandstone Reservoirs

The Biot coefficient is the core parameter of the fluid-solid coupling theory,but currently there is a lack of recommended methods for accurately obtaining the Biot coefficient for specific reservoirs.To solve the problem,a comparison and study of three kinds of Biot coefficient test methods for medium porosity and medium permeability sandstone reservoirs have been conducted in the laboratory,including the Cross-Plotting method,the drainage test method and sonic wave dynamic method.Taking the typical sandstone block in Shengli Oilfield as an example,the experimental study was carried out in three aspects,i.e.permeation theory,rock elastic deformation characteristics and acoustic wave dynamic analysis.The experimental results were compared and the factors affecting the experimental results were discussed.It was found that the Biot coefficient obtained by using the Cross-plotting method was the largest,the Biot coefficient obtained by a drainage test was the second,and the coefficient obtained by using acoustic wave dynamic method was the smallest.The dynamic test value was significantly smaller than the static measurement value.Study results indicate that the drainage test method based on rock elastic deformation theory is recommended for medium porosity and medium permeability sandstone reservoirs,because it has high accuracy and strong reliability.