Selective Water Shutoff Technology Study and Application of W/O Emulsions

Enhancement of oil recovery by emulsion injection: A pore scale analysis from X-ray micro-tomography measurements

“…The results indicated that the sweep efficiency of water injection was strongly enhanced following the injection of the emulsion, with lower-oil ratio in the production wells. Field results presented by Bai et al (Bai et al, 2000) also demonstrated the potential of emulsions as conformance agents, i.e., their capacity to improve the uniformity of the flood front of the injected drive fluid. Various core flooding experiments confirmed that injection of emulsions between two water floodings can improve the oil recovery by 20% or more (Demikhova et al, 2016;Kumar et al, 2012;Mandal et al, 2010b) .The mechanism responsible for the improved oil displacement involves the blocking by the emulsion's dispersed oil droplets of larger pore throats already swept by the water phase, which leads to diversion of subsequent water flow to smaller pores that are still fully saturated by oil (Mandal et al, 2010a;Soo et al, 1986;Soot and Radke, 1986), thus improving the homogeneity of the sweep (Chen et al, 2021;Pei et al, 2017) This diversion mechanism is only efficient if the size of emulsion droplets is matched to the pore throat width (Liu et al, 2019) In oil-wet rock formations, dewetting of oil adsorbed to rock surfaces by emulsification is another observed mechanism of oil mobilization (Ning et al, 2018) Guillen et al (Guillen et al, 2012) showed that emulsion flooding affects oil displacement by the water phase in a J o u r n a l P r e -p r o o f multi-scale fashion, by (i) lowering the mobility of the injected fluid, which leads to a more uniform macroscopic sweep, and (ii) better mobilization of trapped ganglia, which leads to a lower residual oil saturation.…”

Effect of Conformance Control Patterns and Size of the Slug of In Situ Supercritical CO2 Emulsion on Tertiary Oil Recovery by Supercritical CO2 Miscible Injection for Carbonate Reservoirs

“…When an emulsion droplet tries to pass through a smaller pore throat than the droplet’s diameter, a capillary resistance force generates, which is the opposite of the driving force and leads to the redistribution of fluids in the formation. To date, many researchers and engineers have proposed a variety of emulsion treatments for oilfield applications. ,,,− O/W or W/O emulsion’s main advantages include moderate injectivity due to the low bulk viscosity of O/W emulsion, less formation damage, and low cost. ,, This technique can be applied if an O/W or W/O is generated in the formation. Unfortunately, in most cases of field application, the crude oil produced from the reservoir is used to form the emulsion with water in the well site and then injected such emulsion into the reservoir again, which is a risky approach and may result in the additional residual oil from such emulsion left in the reservoir.…”

Conceptual Darcy-Scale Model of Oil Displacement with Macroemulsion

“…Recent field results show the potential of emulsions as conformance agents. The observed blocking mechanisms can be attributed in part to the pressure drop–flow rate response of behavior of emulsion flow in porous media . Similarly, several research groups have proposed that in situ generated emulsions in chemical flooding of heavy oil reservoirs contribute significantly to oil displacement. − …”