A boundary element model for falloff testing in unconventional reservoirs by considering natural fractures

Abstract

Unconventional reservoirs of hydrogen and carbon have gained tons of attention in the recent years, due to economic success of shale oil/gas in the North America. To ensure sufficient production rate, the first and primary step is understanding the unconventional reservoirs by falloff tests. The objective of this study is to develop a new boundary element model for falloff tests, which help the operators to perform a more successful estimation and understanding in unconventional reservoirs. The proposed boundary element model is composed of analytical reservoir solution and numerical fracture solution. The discretization and grids in spatial and temporal dimensions are not required in the proposed boundary element model, which has the analytical characteristics. The boundary element approach is verified by a numerical simulator. We use the new proposed model to analyze the falloff test data of a complex fracture case, namely complex fracture networks. The impacts of fractures on pressure behaviors are also studied with sensitivity analysis. Its applicability and robustness are demonstrated by using examples from actual/synthetic falloff tests in unconventional reservoirs. This work may shed light on a more successful estimation and understanding in unconventional reservoirs by the new boundary element model.