A new sorption-corrected deconvolution method for production data analysis in a shale gas reservoir containing adsorbed gas

Abstract

When characterising a reservoir with the production data acquired from a shale gas well, the rate-normalised pressure (RNP) method is widely used due to its simplicity. However, for sharply varying production data, such as production and shut-in of a well, the RNP method yields erroneous reservoir characteristics. On the other hand, the deconvolution method can overcome these limitations, but it is only applicable for linear pressure-rate relationships. That is, it is not appropriate for production data acquired from a reservoir containing adsorbed gas. This production data shows nonlinear pressure-rate relationship due to the compressibility of desorbed gas, which strongly influenced by the pressure. In this study, in order to utilise the deconvolution method to analyse sharply varying production data containing adsorbed gas in a shale gas reservoir, we propose the linearised relationship of the sorption-corrected pseudopressure and production rate by using a variable substitution method such that it can be correctly implemented for deconvolution. From the results of sorption-corrected deconvolution method, we conduct pressure transient analysis for obtaining shale gas reservoir characteristics.