Pore-Scale Investigation of the Matrix−Fracture Interaction During CO₂Injection in Naturally Fractured Oil Reservoirs

Abstract

Sequestration of CO 2 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 CO 2 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 CO 2 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 CO 2 -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. CO 2 was injected at miscible and immiscible conditions. The focus of the study was on visual porescale analysis of miscibility, breakthrough of CO 2 , and oil/CO 2 transfer between the matrix and fracture under different miscibility conditions. More specifically, the CO 2 -oil interaction near the fracture region inside the matrix was visualized, and its impacts on the further transport of CO 2 inside the matrix by diffusion, transfer of oil from the matrix to the fracture and its flow in the fracture, and CO 2 storage inside the matrix during these processes were analyzed visually.

Microfluidic Studies of Carbon Dioxide

“…This effect may take place due to the presence of thin liquid film surrounding gaseous plugs and may cause the distribution of the dissolved CO 2 between the liquid segments. Surface treatment of the walls of the MF reactors can significantly reduce this effect by suppressing the formation of the liquid film around the plugs 137. The contribution of the gas–liquid mass transfer during the formation of gas plugs to the overall gas–liquid mass transfer, the nonlinear gas–liquid mass transfer behavior in reactive (solvent+reagent) systems and the corresponding change in volume of liquids should be further investigated.…”

“…In addition, studying the underground injection and transport of sc‐CO 2 for CO 2 storage and enhanced oil recovery is of great importance, and high‐pressure MF platforms have recently enabled better understanding of the mechanisms involved in this process 137. 138 Studies conducted in high (up to 40 MPa) pressure‐compatible MF devices fabricated in silicon or glass131 can facilitate better understanding of microscale fluid transport on length scales similar to the pore sizes of underground sedimentary rocks and benefit real‐world efforts on CO 2 storage.…”

Asymmetry Characteristics of Oil Production by Spontaneous Imbibition from Cores with Two Ends Open

“…The spontaneous imbibition of a wetting phase into a porous medium saturated with nonwetting phase is relevant to many practical situations, including papermaking (Bodurtha et al 2005), carbon dioxide sequestration (Er et al 2010), and oil and gas production (Morrow and Mason 2001;Cai et al 2014). In fractured water-wet reservoirs, water is drawn into the matrix system by capillary pressure and expels oil into the fractured system.…”

On the fabrication of PDMS micromodels by rapid prototyping, and their use in two‐phase flow studies

“…For larger pore depth, DRIE results in sloped walls; the slope being larger for bigger depth [Ohara et al, 2010;Yeom et al, 2005;. Deeper pores can be created in glass using chemical etching [Johnston, 1962;Wegner and Christie, 1983;McKellar abd Wardlaw, 1982;Er et al, 2010], but then pore walls will be curved at the bottom, as the erosion process is highly isotropic. Silicon micromodels have the disadvantage that the pore walls are made of two materials.…”