Fracture Network Modeling and Dual-Permeability Simulation of Carbonate Reservoirs

Abstract

Abstract Fractured and fracture-enhanced reservoirs are becoming increasingly important as the world's remaining hydrocarbon assets are developed. New modeling and simulation techniques must be developed to guide business decisions, improve economic forecasts, and maximize productivity. To address this need, a fractured reservoir modeling and simulation workflow was developed to integrate evolving technology for fracture characterization, geologic modeling, and flow simulation. The workflow is based on: common-scale geologic and simulation models;fine-scale element models to compute effective matrix permeability;analysis of fracture data from core, image logs, and outcrop; andintegration of field performance, structure, stratigraphy, and lithology. Directional equivalent fracture permeability, porosity, and matrix block dimensions are estimated using discrete fracture network (DFN) and 3D geologic models, while effective matrix permeability is derived using proprietary technology (patent pending). Fracture analysis consists of identifying structural and stratigraphic controls on fracture data from available sources, and then using this knowledge to derive a set of rules to populate a DFN model. Dual-porosity/permeability reservoir simulation models are built in EMP Power™ Pusing similar grid geometry and cell size, effective matrix properties, and DFN-generated fracture properties. Simulation results show a better history match with less iteration than previous models when compared with multiphase production history. In our test cases, dual-porosity/ permeability models more accurately capture the impact of fractures on fluid flow than do single-medium models. Our study also demonstrates an effective and efficient process for dual-porosity/permeability modeling and simulation of fractured reservoirs. Fractured Reservoir Modeling and Simulation Workflow The integrated workflow discussed here addresses fractured reservoir characterization and fluid-flow simulation, using ExxonMobil proprietary and vendor software tools. It generates effective matrix properties, directional fracture permeabilities, and equivalent matrix block dimensions that are used to build dual-porosity/dual-permeability reservoir simulation models. The workflow is as follows.