Iranian Journal of Oil and Gas Science and Technology

Abstract Recently, nanoparticles have been used to improve oil and gas production volume and enhance oil recovery (EOR). Based on our recent research, using nanoparticles such as silica and calcium oxide has a good potential for changing mechanisms in the porous media, such as interfacial tension and wettability. Low permeability carbonate plugs were selected to determine the application of nanoparticles in the porous media. Two main steps were used: 1) Using CaO and SiO₂ nanoparticles for wettability alteration, interfacial tension reduction, and improving fluid flow through porous media, and 2) Surveying the application of nanoparticles to the water alternating gas (WAG) (nanoparticles (NCs)-assisted WAG) test. The zeta potential values were stable at –56.4 ± 2 mV and –44.0 ± 3 mV for calcium oxide and silica nanoparticles, respectively, at an optimum nanoparticle concentration of 15 ppm. Calcium oxide and silica nanoparticles effectively altered the wettability from oil-wet to water-wet by surveying the intersection of two-phase relative permeability. Moreover, CaO nanoparticles performed better in low permeability carbonate porous media than SiO₂ nanoparticles regarding wettability alteration to water wetness. Based on the results and a better grade of CaO, it was selected for performing NCs-assisted WAG tests at WAG ratios of 1:1, 40 ℃, and 15 ppm. The recovery factor increased from 42.9% to 73% in the presence of CaO during NC-assisted WAG tests, and residual oil saturation decreased from 40.9% to 19.4%.

Abstract Due to the limitations of existing natural gas fumigation systems, including the bypass and injection systems, there is a need for the design of a new system with fewer restrictions. This paper addresses this issue by conducting a thermodynamic analysis of the performance of a new system, called the ejector gas perfuming system, across a wide range of parameters, including primary gas pressure (Pg = 500-5500 kPa) and secondary gas pressure (Ps = 200-400 kPa). The results demonstrate that the ejector's performance is primarily influenced by two key factors: the pressure at the ejector's exit and the ejector's entrainment ratio. The findings indicate that the ejector performs optimally when Ps > 250 kPa and 1850 kPa ≤ Pg ≤ 5200 kPa. Outside of this range, its performance declines.

Abstract One of the most important methods for enhancing oil recovery in reservoirs is chemical flooding. The performance and efficiency of these processes in increasing oil recovery depend on several factors, including the rock and fluid properties of the reservoir. Therefore, a critical step in evaluating the effectiveness of these methods is conducting laboratory studies and calculating the potential of chemical agents to recover oil. Optimal design, using new approaches such as novel chemical agents or comprehensive studies of chemical flooding at the core scale, is essential to make chemical flooding more cost-effective.
For this purpose, a laboratory study combined with integrated simulation was performed to identify the effective mechanisms in low-salinity water–polymer injection and to determine the necessary and dominant conditions for improving recovery in Iranian carbonate reservoirs. Initially, four injection scenarios were tested in the laboratory: water injection–polymer injection–low-salinity water injection, water injection–low-salinity water injection–polymer injection, water injection–low-salinity water–polymer injection, and low-salinity water injection–low-salinity water–polymer injection. Subsequently, low-salinity water–polymer flooding was simulated using the Eclipse 100 simulator to evaluate the effect of polymer injection on oil recovery and oil trapping in the reservoir rock. Finally, simulation results were validated against laboratory data.
The results demonstrated that low-salinity water injection followed by low-salinity water–polymer injection showed the best performance, improving secondary oil recovery by 63.45%, with wettability alteration identified as a key mechanism for enhanced oil recovery. The study also showed that under optimal conditions, despite mechanical degradation of the polymer, recovery of initial oil in place could reach up to 85% through controlled adsorption of polymer on the rock surface. Furthermore, initial polymer injection was found to help reduce the amount of polymer required to achieve residual oil saturation.