Pore-Scale Investigation of the Matrix Fracture Interaction During Co 2 Injection in Naturally Fractured Oil Reservoirs
Er, V.; Babadagli, T.; Xu, Z.
Energy and Fuels 24(2): 1421-1430
ISSN/ISBN: 0887-0624 DOI: 10.1021/ef901038v
Sequestration of CO2 into oil and gas reservoirs gains respect as an economically and environmentally convenient way of reducing emissions of greenhouse gas and increasing hydrocarbon production at the same time. Because the naturally fractured reservoirs (NFRs) constitute a great portion of current and potential CO2 injection applications, it is essential to understand the matrix−fracture interaction during such applications to maximize the efficiency of the process, maximizing incremental oil production with maximum CO2 storage. Visualization of the phase behavior and flow patterns to/from the fracture and from/to the matrix is critical in understating the process and discovering ways to co-optimize the oil production−greenhouse gas storage process. Hence, pore-scale behavior of the CO2−oil interaction was investigated experimentally using homo- and heterogeneous fractured micromodels. Glass-etched microfluidic models were employed to investigate the pore-scale interaction between the matrix and fracture. Models were prepared by etching homo- and heterogeneous microscale pore patterns with a fracture in the middle of the model on glass sheets bonded together and then saturated with colored n-decane as the oleic phase. CO2 was injected at miscible and immiscible conditions. The focus of the study was on visual pore-scale analysis of miscibility, breakthrough of CO2, and oil/CO2 transfer between the matrix and fracture under different miscibility conditions. More specifically, the CO2−oil interaction near the fracture region inside the matrix was visualized, and its impacts on the further transport of CO2 inside the matrix by diffusion, transfer of oil from the matrix to the fracture and its flow in the fracture, and CO2 storage inside the matrix during these processes were analyzed visually.