Mathematical modeling of gravity and buoyancy effect on low interfacial tension spontaneous imbibition in tight oil reservoirs

Abstract

Considering capillary force, viscous force, and gravity and buoyancy effects due to the oil–water density difference during the imbibition process, a new mathematical model for core‐scale spontaneous imbibition considering gravity and buoyancy is established. The imbibition rates with and without gravity and buoyancy in high‐, low‐, and ultralow‐interfacial tension (IFT) solutions are compared. The study shows that oil buoyancy can accelerate the imbibition rate, and with increasing core permeability and decreasing IFT, the differences in imbibition rate with and without gravity and buoyancy become more significant. At a high IFT of dozens of mN/m, the gravity and buoyancy effects are nonsignificant and can be ignored, but at a low IFT such as at 0.355 mN/m and a core permeability above 1 mD, gravity and buoyancy must be considered in spontaneous imbibition simulations. In low‐IFT solutions, the critical inverse Bond number when gravity and buoyancy must be considered is approximately 1 × 10−2.

Prediction of spontaneous imbibition with gravity in porous media micromodels

“…Next, we study spontaneous imbibition with high viscosity ratio, which is commonly encountered in natural and industrial applications (Elizalde, Urteaga & Berli 2015; Wijshoff 2018; Wang & Zhao 2021). Here, the viscosity ratio is set to or , and various values of contact angle, micromodel depth and gravitational acceleration are considered.…”

“…Due to the 1-D similarity of compact displacement to capillary-driven flow in a single circular capillary, researchers have extended the Lucas-Washburn equation to the quantification of compact displacement in porous media by considering the geometrical complexity of the pore structure (Cai et al 2021). Typically, the geometrical complexity can be considered by using the equivalent radius derived from the fractal geometry theory (Cai et al 2010;Li & Zhao 2012;Shi, Yassin & Dehghanpour 2018;Wang & Zhao 2021), or by using an effective hydraulic radius computed from the macroscopic properties of porous media, including the permeability, porosity, pore shape and so on (Benavente et al 2002;Fries & Dreyer 2008;Babchin et al 2016). However, the former suffers from ignoring the connectivity of porous media, since a porous medium is ideally simplified as a bundle of capillaries without interaction in the fractal geometry theory.…”

“…Typically, the geometrical complexity can be considered by using the equivalent radius derived from the fractal geometry theory (Cai et al. 2010; Li & Zhao 2012; Shi, Yassin & Dehghanpour 2018; Wang & Zhao 2021), or by using an effective hydraulic radius computed from the macroscopic properties of porous media, including the permeability, porosity, pore shape and so on (Benavente et al. 2002; Fries & Dreyer 2008; Babchin et al.…”

Experimental Mechanism for Enhancing Oil Recovery by Spontaneous Imbibition with Surfactants in a Tight Sandstone Oil Reservoir

“…Surfactants have been widely applied to enhance the oil recovery of spontaneous imbibition in tight sandstone oil reservoirs. − Sheng combined theoretical analysis and numerical simulation to investigate the various factors influencing imbibition and found that the primary controlling factor for spontaneous imbibition was initial wettability. Meng et al analyzed the mechanism of surfactants improving imbibition recovery by combining imbibition experiments and numerical simulations; the study showed that the recovery of tight oil reservoirs can be enhanced by either reducing residual oil saturation or increasing IFT.…”

Pore-Scale Study on Shale Oil–CO2–Water Miscibility, Competitive Adsorption, and Multiphase Flow Behaviors

“…Thus, only oil–water and CO 2 –water interfacial tensions are considered. The CO 2 –water interfacial tension is generally 30 mN/m at typical reservoir conditions (343 K and 20 MPa), − while that of oil–water is generally 44 mN/m. − As the CO 2 mole fraction in the oil phase increases, the CO 2 /oil–water interfacial tension approaches to that of CO 2 –water . In LB simulations, it is difficult to adjust interfacial tension independently from the diffusion, adsorption, and surface wettability.…”