Efficiency of Miscible Displacement in Fractured Porous Media

Efficiency of Miscible Displacement in Fractured Porous Media Japan Jitendrabhai Trivedi; Japan Jitendrabhai Trivedi U. of Alberta Search for other works by this author on: This Site Google Scholar Tayfun Babadagli Tayfun Babadagli U. of Alberta Search for other works by this author on: This Site Google Scholar Paper presented at the SPE Western Regional/AAPG Pacific Section/GSA Cordilleran Section Joint Meeting, Anchorage, Alaska, USA, May 2006. Paper Number: SPE-100411-MS https://doi.org/10.2118/100411-MS Published: May 08 2006 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Get Permissions Search Site Citation Trivedi, Japan Jitendrabhai, and Tayfun Babadagli. "Efficiency of Miscible Displacement in Fractured Porous Media." Paper presented at the SPE Western Regional/AAPG Pacific Section/GSA Cordilleran Section Joint Meeting, Anchorage, Alaska, USA, May 2006. doi: https://doi.org/10.2118/100411-MS Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Search Dropdown Menu nav search search input Search input auto suggest search filter All ContentAll ProceedingsSociety of Petroleum Engineers (SPE)SPE Western Regional Meeting Search Advanced Search AbstractDuring the injection of fluids that are miscible with oil for enhanced oil recovery, oil recovery and transport of the injectant are controlled by fracture and matrix properties in naturally fractured reservoirs (NFR). For such systems, the transfer between matrix and fracture due to diffusion is the main oil recovery mechanism. Similar processes can be encountered during the sequestration of greenhouse gases, and transport of contaminants in subsurface reservoirs. Understanding the effects of the parameters on the dynamics of the process is essential in modeling such processes. In fact, the description of matrix fracture interaction for dual-porosity dual-permeability models developed for NFRs is still a challenge.Experiments were performed to study the process of diffusion during flow in fracture. 2-inch diameter and 6-inch length Berea sandstone and Indiana limestone samples were cut cylindrically. An artificial fracture spanning between injection and production ends was created and the sample was coated with heat shrinkable teflon tube. A miscible solvent (heptane) was injected from one end of the core at a constant rate. The effects ofoil type (mineral oil and kerosene),injection rates,orientation of the core,matrix wettability (changed by aging the cores),core type (a sandstone and a limestone), andamount of water in matrix on the recovery performance were examined.The oil recovery for different matrix sizes, wettabilities, permeabilities, orientations, oil viscosities, and oil-heptane diffusion coefficients were correlated to the injection rate. Then, the ratio of matrix recovery to heptane injected was correlated to the newly defined dimensionless group (fracture diffusion index, FDI). The FDI is the ratio of fracture flow parameters (viscous forces) to matrix diffusion parameters. A critical FDI that maximizes the oil recovery while minimizing the amount of the injected fluid was defined. The process efficiency in terms of the time required for the recovery instead of the amount of solvent injected was also investigated.It is expected that the experimental results and the dimensionless group, FDI, will be useful in deriving matrix-fracture transfer function for diffusion that is controlled by the flow rate, matrix and fluid properties.IntroductionA large proportion of the world's proven oil has been found in reservoir rocks that are naturally fractured. Understanding matrix-fracture interaction presents a unique challenge for enhanced oil recovery and greenhouse sequestration in this type of reservoirs.Recovery mechanism of matrix-fracture system has been studied at laboratory scale since 1970's. Thompson and Mungan[1] compared displacement velocity to critical velocity (VC) and showed its effect on recovery efficiency. Firoozabadi and Markeset[2] showed the effect of matrix/fracture configuration and fracture aperture on first contact miscible efficiency. They also presented capillary pressure contrast of matrix-fracture as major driving force. Matrix fracture interaction in fractured rocks for different types of fluids was investigated computationally[3–4] and experimentally[5–6] in different studies.The diffusion process and correlations of the capillary pressure with variation of interfacial tension were also investigated[7–9]. Saidi[10] studied the diffusion/stripping process in fractured media. Morel et al.[7] performed diffusion experiments with chalk and studied the effect of initial gas saturation. Analytical and numerical solutions for the diffusion process in the fracture and transport to the matrix are also available. [8, 11–13]More recently, static experiments were reported on the diffusion process from fracture to matrix[14–15]. There are also experimental methods for calculating diffusion coefficients between two fluid systems[16–19]. But within the porous media transfer by diffusion depends on the conditions at the boundaries and fracture geometry as well as flow conditions[11]. The mechanism of gas injection into a fractured porous media is governed by convection, dispersion and diffusion. Most mixing (dispersion) is mainly caused by adjacent rock block (rock matrix), variations in velocity due to fracture roughness, mixing at fracture intersections, variations in velocity due to differing scales of fracturing variations in velocity due to variable fracture density. Recovery in fractured reservoirs requires the determination of transfer parameters between fracture and matrix. Keywords: flow in porous media, orientation, Fluid Dynamics, total oil, Efficiency, enhanced recovery, cumulative production, fractured porous media, experiment, Injection Rate Subjects: Reservoir Fluid Dynamics, Improved and Enhanced Recovery, Flow in porous media This content is only available via PDF. 2006. 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