Numerical Investigation on EOR in Porous Media by Cyclic Water Injection with Vibration Frequency

Abstract

Water injection with an oscillatory pressure boundary is a promising technology, which can achieve a more economical and environment-friendly EOR (enhanced oil recovery). However, due to the unclear critical injection frequency, its oil production performance has been unstable and is far from reaching the optimal level. Here, a numerical model is established for oil recovery by the water injection with the oscillatory boundary condition to find out the critical frequency for the optimal EOR. The correlations between the water injection frequency and the EOR level at diverse oil–water surface tensions and oil viscosities are integrated into the model. Our numerical model reveals that an optimal EOR of roughly 10% is achieved at the critical water injection frequency compared with water injection without an oscillatory boundary. The EOR mechanism is revealed showing that upon water injection with the optimum frequency, the formation of the preferential pathways is inhibited and the pressure transmits to the wall sides to displace the oil. Moreover, it is indicated that the required critical frequency increases with higher surface tension and larger oil viscosity. In addition, the difference between the residual oil saturation at the optimal frequency increases with the increase in surface tension compared with water injection without an oscillatory boundary. Last but not least, it is elucidated that at a constant injection frequency, a higher EOR is achieved when the water–oil surface tension is lower but the oil viscosity is larger. Our work promises economic, eco-friendly and controllable enhanced oil recovery.

Determining the effect of vibrating wave swabbing on the functional processes in carbonate low-permeability reservoirs

“…-the use of numerical modeling methods, -devising new experimental research methods; -the use of a combined approach, i.e., a combination of laboratory studies with numerical modeling and analytical calculations. This is the approach used in works [7,8]; however, the authors did not take into account the influence of some important factors, such as the amplitude of pressure fluctuations and the frequency of fluctuations. The results of the work have not been verified on real objects.…”

“…Our analysis of the dependence of permeability coefficient of the reservoir on the volume of sampled liquid is illustrated in Fig. 8 and equation (7).…”