Events

Supervisor: Quoc Nguyen

Abstract:

"Novel Solvent Injection and Conformance Control Technologies For Fractured Viscous Oil Reservoirs"

Fractured viscous oil resources hold great potential for continued oil production growth globally. However, many of these resources are not accessible using currently-used commercial technologies. The current technologies of choice require steam injection, which limits operation to high steam saturation temperatures. Several steam-solvent processes have been proposed to lessen steam dependency, but they still require operating temperatures too high for many projects. There is a strong need for a low temperature technology for viscous oil production from fractured reservoirs. This study explores a novel, low temperature solvent injection strategy targeting fractured systems. The strategy builds on three current technologies – N-Solv, VAPEX, and Gas-Oil Gravity Drainage (GOGD). The production is controlled by two mechanisms depending on the phase of the injected solvent in-situ. During the initial heating period when the solvent is in the liquid phase, liquid extraction occurs. When the reservoir reaches the injection temperature and the solvent is in the vapor phase, solvent-enhanced film gravity drainage occurs. A preliminary history-match effort of the experimental work showed that pure phase fluid properties are sufficient to model the liquid extraction process, but relative permeability in addition to partitioning coefficients must be included to model solvent-enhanced film gravity drainage.

Fractured viscous reservoirs, like all heterogeneous reservoirs, suffer from conformance control issues under any injection strategy. Preferential injection into fractures can result in early breakthrough and large unswept areas of high oil saturation. A variety of conformance control techniques, including polymer and silica gel treatments, have been designed to block flow through the swept zones, but both have drawbacks. Over a certain range of salinities, silica nanoparticle dispersions form a gel in bulk phase behavior tests. This work determines the equilibrium phase behavior of silica nanoparticle dispersions in the presence of sodium chloride (NaCl) with four phase regions classified as a function of salinity and nanoparticle concentration. Additionally, the gelation time is found to decrease exponentially as a function of silica concentration, salinity, and temperature. During core flood tests under matrix and fracture injection, the gels were show to provide sufficient conductivity reduction to warrant continued study.