Pore-Level Investigation of the Influence of Wettability and Production Rate on the Recovery of Waterflood Residual Oil with a Gas Assisted Gravity Drainage Process

Abstract

Gas assisted gravity drainage (GAGD) is an oil recovery mechanism that can be implemented after waterflood to enhance the recovery of oil. The performance of postwaterflood GAGD is affected by a variety of parameters that determine the balance between capillary, gravitational, and viscous forces. In this research, the influence of the wettability, heterogeneities, and production rate on the recovery of oil have been studied at the pore level to recognize phenomena affecting mechanisms of oil recovery visualizing interfaces in a newly designed micromodel that contains a coarse pore network covered by fine capillaries. Experimental results show that regions with high oil saturation (oil-bank) were formed ahead of the gas front in both oil-wet and water-wet micromodels when the production rate was low. Under oil-wet conditions, the size of the oil-bank was greater, and the recovery of oil initiated prior to a gas breakthrough. Under water-wet conditions, the flow of the residual oil after a gas breakthrough was initially restricted by the presence of the residual water in small pores and fine capillaries. However, high oil recovery was finally obtained upon an effective reduction of the water saturation extending the time of the process. Under both wettability conditions, increasing the drainage rate contributed to the instability of gas fronts and early gas breakthroughs without a remarkable oil recovery. The experimental result implies that, although the oil production characteristics under oil-wet and water-wet conditions are different, both of the wettability states have potential for the implementation of postwaterflood GAGD.

Evaluation of the interFoam solver in the prediction of immiscible two-phase flow in imbibition and drainage on the pore-doublet system

“…Mahmoodi et al developed a visualization method to capture multiphase fluid displacement in micro-models [12]. Saturation evolution were quantified during EOR process at pore scale [13][14][15]. The behavior of imbibition and drainage is visualized experimentally based on viscosity ratio and capillary number by Guo and Aryana [16].…”

Performance demonstration of gas-assisted gravity drainage in a heterogeneous reservoir using a 3D scaled model

“…Because of the water partition effect, the injected water has to aggregate the dispersed crude oil to form a membrane oil with low ow resistance, inhibiting the formation of membrane ow and leading to a lower recovery factor of GAGD than that of the oil-wet reservoir. 22,23 The distribution of uid directly inuences the recovery factor of gas drive, especially GAGD. The distribution and ow form of oilgas-water in porous media can be described by the spreading coefficient, 24 which represents the equilibrium relationship among the interface tension (IFT) of oil, water, and gas.…”

Hydrophilic Nanoparticle-Based Enhanced Oil Recovery: Microfluidic Investigations on Mechanisms

“…Microfluidics ,, provide direct visualization of micron-scale flow phenomena and are a powerful tool to investigate pore-scale flow mechanics and other physics that are not easy to study directly on coreflood or sandpack experiments. In addition, direct observations on microfluidics platforms can also be easily compared with numerical modeling works. − Specifically, porous micromodels, with names matching their applications as “rock-on-a-chip”, “soil-on-a-chip”, “reservoir-on-a-chip”, “aquifer on a chip”, etc., have been applied to visualize the displacement flow process in porous media, − including some works on EOR with direct injection of nanofluids. − NPs-based secondary oil recovery was studied by Ryles et al They showed that the steady-state IFT between the nanofluid and oil decreases with an increase in the NP concentration, and that increased NP concentration is positively related to final oil recovery. The NP deposition on the solid surface and its positive effect on surface wettability were also visualized. , Bazazi et al compared waterflooding, surfactant flooding, and NP flooding in a glass micromodel saturated with heavy oil and concluded that emulsion formation during heavy oil displacement with chemicals is a major factor in incremental recovery.…”