A New Predictive Method for CO2-Oil Minimum Miscibility Pressure

Abstract

Gas injection processes are among the effective methods for enhanced oil recovery. Miscible and/or near miscible gas injection processes are among the most widely used enhanced oil recovery techniques. The successful design and implementation of a miscible gas injection project are dependent upon the accurate determination of minimum miscibility pressure (MMP), the pressure above which the displacement process becomes multiple-contact miscible. This paper presents a method to get the characteristic curve of multiple-contact. The curve can illustrate the character in the miscible and/or near miscible gas injection processes. Based on the curve, we suggest a new model to make an accurate prediction for CO2-oil MMP. Unlike the method of characteristic (MOC) theory and the mixing-cell method, which have to find the key tie lines, our method removes the need to locate the key tie lines that in many cases is hard to find a unique set. Moreover, unlike the traditional correlation, our method considers the influence of multiple-contact. The new model combines the multiple-contact process with the main factors (reservoir temperature, oil composition) affecting CO2-oil MMP. This makes it is more practical than the MOC and mixing-cell method, and more accurate than traditional correlation. The method proposed in this paper is used to predict CO2-oil MMP of 5 samples of crude oil in China. The samples come from different oil fields, and the injected gas is pure CO2. The prediction results show that, compared with the slim-tube experiment method, the prediction error of this method for CO2-oil MMP is within 2%.

How Is Ultrasonic-Assisted CO2 EOR to Unlock Oils from Unconventional Reservoirs?

“…Among them, the method of characteristic theory and the mixing-cell method is one of the most classical methods for calculating MMP. Ge et al [13] proposed a prediction model for CO 2 -oil MMP, which considered multi-stage contact based on the method of characteristic theory and the mixing-cell method. This method is used to calculate the MMP of the CO 2 -oil system before and after ultrasonic treatment in this paper.…”

“…Reducing MMP is a common method to realize CO 2 miscible flooding [10,11]. The purity of injected CO 2 , the viscosity of formation crude oil, formation temperature, the composition of crude oil, and pore size are all influencing factors of MMP [12][13][14][15]. The main direction of reducing MMP between crude oil and CO 2 is to change the properties of carbon dioxide and crude oil [16][17][18][19].…”

How Ultrasonic-Assisted CO₂ EOR to Unlock Oils From Unconventional Reservoirs?

“…Among them, the method of characteristic theory and the mixing-cell method are one of the most classical methods for calculating MMP. Dangke Ge et al [59] propose a prediction model of CO2oil MMP considering multi-stage contact based on method of characteristic theory and the mixing-cell method. This method is used to calculate the MMP of CO2-oil system before and after ultrasonic treatment in this paper.…”

“…Reducing MMP is a common method to realize CO2 miscible flooding [9,10]. Purity of injected CO2, viscosity of formation crude oil, formation temperature, composition of crude oil and pore size are all influencing factors of MMP [11][12][13][14]. The main direction of reducing MMP between crude oil and CO2 is to change the properties of carbon dioxide and crude oil [15][16][17][18].…”

Accurate determination of nano-confined minimum miscible pressure to aid CO2 enhanced oil recovery and storage in unconventional reservoirs

“…Existing methods for predicting the MMP of CO 2 -oil systems typically involve experimental tests (Novosad et al, 1990;Nguyen et al, 2015;Zhang et al, 2019), empirical modeling (Shokir, 2007;ZareNezhad, 2016), and numerical simulations (Zhao and Fang, 2020;Ge et al, 2021). Experimental techniques, such as the slim-tube experiment (Hao et al, 2020;Lu et al, 2022), rising bubble apparatus (Li and Luo, 2017), and vanishing interfacial tension tests (Safaei et al, 2023), have been widely utilized to measure the MMP under different injected gases.…”