The Analysis of Shale Gas Reservoir with Deconvolution Method

In analyzing the production data obtained from shale gas reservoir, the rate-normalized pressure (RNP) method has been widely used in shale gas industry due to its simplicity. However, for sharply varying production caused from production and shut-in of the well, and for pressure-interfered production data, RNP method gives erroneous results in evaluation the reservoir characteristics. Meanwhile, deconvolution method can overcome the limit of RNP method for sharply varying production data. However, because the deconvolution method is only applicable to linear relationship in pressure-rate data, it is not possible to analyze the production data obtained from coal seam or shale gas reservoir containing sorption characteristics. This production data shows nonlinear relationship in pressure-rate data due to the compressibility of desorbed gas which is strong function of pressure.

In this study, the deconvolution method implemented with the sorption-corrected pseudopressure was proposed for being able to analyze not only sharply varying production data but also pressure-interfered data acquired from multiwell containing sorption characteristics. In this aspect, the sorption-corrected pseudopressure was derived from material balance equation for linearizing the pressure-rate relationship through a variable substitution method.