An Integrated Approach of Uncertainty Assessment for Coalbed Methane Model

Abstract

This study deals with quantitative detection of parameters uncertainty in coalbed methane(CBM) modelling and a systematic and integrated workflow is developed to analyze the uncertainty of CBM model. In structure modelling, the uncertainty of measure depth (MD) and coal thickness were analyzed by disturbing the structure surfaces or thickness surfaces while fixed at the well locations. In property modelling, an analysis of the residual distribution between each correlation and its measurements was used to characterize the uncertainty of each parameter. Sensitivity analysis was performed for the parameters, such as gas content, structure surfaces, coal thickness, density, ash content, etc., to evaluate the uncertainty of original gas in place (OGIP). The critical sensitive attributes were used to build multiple realizations to determine the P90, P50 and P10 of OGIP. The low, middle and high probabilistic geological models were achieved corresponding to the probabilistic OGIP, and used for the following reservoir simulation and development plan design.