Evaluation of Bakken Performance Using Coreflooding, Well Testing, and Reservoir Simulation

摘要

The success of oil production in North Dakota Bakken should be credited to advanced completion and stimulation techniques. The abundance of data on well production, core analyses and flooding, geologic reservoir characterization, and pressure transient testing has enhanced reservoir evaluation. Understanding matrix and fracture contribution to daily oil production is the key to identifying reservoir drivers affecting the lifelong well productivity. In this paper, we will present an application of core flooding, mini-frac and pressure build-up tests, decline curve analysis and reservoir simulation history matching to achieve reliable long-term reservoir performance predictions. This approach could lead to developing an integrated workflow for determining the performance drivers in the greater Bakken. Information presented in this paper includes well performance data from several Bakken fields, displacement results on selected cores, mini-frac and pressure transient analyses, and history matching using decline curve analysis and numerical simulation. Specifically, the matrix permeability from core measurements is on the order of 10-4 md while the permeability from well testing is on the order of 10-2 md. The latter represents the combined contributions of micro-fractures and matrix permeability. Reservoir simulation also shows that a single-porosity system, using only the matrix permeability from the core analysis, is not sufficient for matching well production performance without having a secondary permeability and porosity (micro-fractures). The dual-porosity nature of the reservoir was confirmed by a long-term pressure build-up test.