|dc.description.abstract||New complexities have been identified in fractured shale reservoirs, such as multi-porosity types and non-Darcian transport and storage mechanisms in the shale nano-pores. Reservoir simulation serves as a convenient approach for reservoir management. However, commercial reservoir simulators remain as black boxes for reservoir engineers. Currently none of these simulators offer a full-featured tool to solve those problems.
In this work, a general Multi-Porosity Model is developed to handle the reservoir heterogeneity in the fractured reservoirs. This model allows the simulation of any number of porosity systems, and thus it resolves the limited number of porosity types in the Dual-Porosity Models. Moreover, this model allows arbitrary inter-porosity and intra-porosity connections, so it breaks the limitation of fixed connections in the Dual-Porosity Models. In addition, a novel porosity subdivision algorithm has been designed, and a new shape factor is correspondingly derived to consider the porosity subdivision. Therefore, the transient flow can be accurately approximated by the high resolution from the subdivision. Finally, the Multi-Porosity Model is implemented as a standalone unstructured tool, and thus it is able to be flexibly interfaced with unstructured reservoir simulators. This approach is successfully applied to model fluid transport in the fractured reservoirs and shale gas reservoirs.
The second thrust area is the development of a fully compositional simulator, General Unstructured Reservoir Utility (GURU). GURU is based on Control-Volume Finite-Difference method, so it can conveniently handle different grid discretization methods, such as Cartesian grids, discrete fracture models and Multi-Porosity Models etc. Besides, a novel class of compositional space preconditioned VLE methods has been proposed for efficient compositional simulation, and it speeds up the flash calculation by a more reliable initial estimate. In addition, mechanisms are flexibly considered in GURU. Darcy flow is the basic flow mechanism, and multi-component adsorption is optionally considered for fluid storage. Gas slippage and Knudsen diffusion are also incorporated for the shale gas transport. Furthermore, a unique shale reservoir modeling workflow is established for mechanistic investigation. Heterogeneity of the fractures is upscaled by sector models, and multi-porosity types are honored by the Triple-Porosity Model, and fluid storage and transport physics are implemented in GURU.||en