A Novel Semianalytical Model for the Relationship between Formation Pressure and Water Saturation in Coalbed Methane Reservoirs

The accuracy of the relationship between formation pressure and water saturation has a direct impact on predicting production performance coal reservoirs. As result, researchers are becoming more interested in this connection. most commonly used method to evaluate connection is semianalytic method, but it disregards matrix shrinkage pore compressibility, resulting inaccurate estimations for A material balance equation that considers effect cleat porosity as well gas–water relative permeability curve, first time study establish model saturation. Furthermore, extends proposed pressure–saturation predict cumulative gas recovery, resolving difficult problem calculating recovery coalbed methane To verify its accuracy, compares with numerical simulations previous methods; results comparison show under calculated by closer simulation. Sun’s ignores larger calculation results. findings indicate compressibility cannot be ignored, can replace simulation simple accurate evaluation, which applied estimation closed increases semianalytical broadens application. It critical prediction reservoir forecasting dynamics.