Unconventional Shale Reservoir’s Property Estimation through Modeling, Case Studies of Australian Shale

Abstract

A simplified approach is introduced to model production from shale gas resources. In this approach, a multi-fractured horizontal gas well in a shale formation is divided into four zones. Shale formation between each pair of hydraulic fractures consists of four zones: compacted zone around well-bore (1), shale matrix (2), induced fractures (3) and main hydraulic fractures (4). The main contribution of this study is considering varying permeability for each specific zone implemented in the mathematical presentation of gas flow in shale. Further, gas desorption and slippage effect are applied to the model to capture the realistic gas flow in shale. The nonlinear partial differential equation of gas flow obtained from mass conservations law is then solved numerically for each specific zone with respect to their appropriate boundary conditions. This approach then is applied to three case studies, Cooper Basin, Georgina and Galilee shale. A history matching of the mentioned formations is accomplished to find the most uncertain parameters undertaken through this simplified approach. Results of this study are in an agreement with other methods and it is demonstrated that the simplified approach provides more accurate production forecast for the well-established Georgina asset and is in a good agreement for Cooper and Galilee. This study is also valuable since it provides some rough estimation for shale rock characteristics as the basis for rigorous simulation studies.