Modeling Study of the Unconventional Bakken Formation for Gas Injection EOR

Summary The application of horizontal well and hydraulic fracturing technologies makes it profitable to produce a significant quantity of oil and gas from the extremely tight Bakken Formation. Typically, these fractured horizontal wells produce 5%-15% of original oil in place in the primary depletion stage, leaving a significant volume of oil in the reservoir. However, enhanced oil recovery (EOR) techniques have shown promise and are critical to the future development of the Bakken Formation. A series of modeling and simulation activities have been conducted in this study aimed at effectively modeling and simulating the production/EOR processes in complex fractured unconventional reservoirs. A geologic model and three simulation models with different scales were developed to investigate the flow behavior in the tight reservoirs and predict the gas injection EOR performance. Multiple interacting continua (MINC) and embedded discrete fracture model (EDFM) approaches were used to construct the fracture-matrix grid blocks in the models. The MINC method captured the early rapid transient flow but encountered numerical challenges in the gas injection simulation. The EDFM approach provided an effective way to improve simulation efficiency by reducing numerical failures in the computational process, which is critical for unconventional reservoir simulation efforts.