Rezk Mohamed Gamal, Foroozesh Jalal
Petroleum Engineering Department, Universiti Teknologi PETRONAS, Perak, Malaysia.
Heliyon. 2019 Jul 26;5(7):e02057. doi: 10.1016/j.heliyon.2019.e02057. eCollection 2019 Jul.
This paper investigates the phase behavior and mutual interactions between a light crude oil and CO at high pressures and high temperatures (HPHT). To do so, we have measured PVT properties of the CO-oil system at HPHT using a PVT setup. We have also tried to present a detailed methodology for measuring PVT properties of CO-oil systems and highlight the difficulties such as oil vaporization by CO during the experiments. A crude oil sample, collected from a Malaysian oil field, was used here. Our experiments indicated that, CO solubility in the oil increased at higher pressures when measured at a fixed temperature. Our experiments also showed that increasing the test temperature would reduce CO solubility in the oil, while its effect is more significant at higher pressures. The swelling factor (SF) measurements showed an increasing trend with pressure up to a certain value so-called extraction pressure, at which, the SF started to be reduced even became less than one. The measurements of oil viscosity indicated that CO dissolution in the oil sample could reduce the mixture viscosity up to 61%. The interfacial tensions between CO and the crude oil at different pressures were also measured while the results were used to estimate the minimum miscibility pressure (MMP) and the first contact miscibility (FCM) pressure. The IFT measurements at various pressures displayed a reduction trend as a result of more CO dissolution in the oil but with two different slopes. That is, at lower pressure values, the measured IFTs were sharply reduced with pressure, while the reduction rate of the IFT became less when pressures exceeded the extraction pressure. This study helps with determining the optimum pressure and temperature conditions of CO-oil systems to have a minimum IFT, a maximum CO solubility and SF, and a minimum oil viscosity that are favorable for CO-enhanced oil recovery projects. Additionally, the methodology presented here gives guidelines on how to design PVT experiments of CO-oil systems for petroleum and chemical engineering applications.
本文研究了轻质原油与一氧化碳在高温高压（HPHT）下的相行为及相互作用。为此，我们使用高压物性测试装置（PVT装置）测量了高温高压下一氧化碳 - 油体系的PVT性质。我们还尝试给出了一种测量一氧化碳 - 油体系PVT性质的详细方法，并强调了实验过程中诸如一氧化碳导致油汽化等困难。这里使用了从马来西亚一个油田采集的原油样品。我们的实验表明，在固定温度下测量时，一氧化碳在油中的溶解度随压力升高而增加。我们的实验还表明，提高测试温度会降低一氧化碳在油中的溶解度，而在较高压力下其影响更为显著。膨胀因子（SF）测量显示，在达到所谓的萃取压力这一特定值之前，膨胀因子随压力呈上升趋势，在该压力下，膨胀因子开始下降甚至小于1。油粘度的测量表明，一氧化碳溶解在油样中可使混合物粘度降低达61%。还测量了不同压力下一氧化碳与原油之间的界面张力，结果用于估算最小混相压力（MMP）和首次接触混相（FCM）压力。在不同压力下进行的界面张力测量显示，由于更多的一氧化碳溶解在油中，界面张力呈下降趋势，但有两个不同的斜率。也就是说，在较低压力值时，测量得到的界面张力随压力急剧降低，而当压力超过萃取压力时，界面张力的降低速率变小。本研究有助于确定一氧化碳 - 油体系的最佳压力和温度条件，以实现最小界面张力、最大一氧化碳溶解度和膨胀因子以及最小油粘度，这些条件有利于一氧化碳强化采油项目。此外，这里给出的方法为石油和化学工程应用中如何设计一氧化碳 - 油体系的PVT实验提供了指导。
