{"title":"Complex phase behaviours related to gas injection in reservoir fluids","authors":"F.E. Benelli, G.O. Pisoni, M. Cismondi-Duarte","doi":"10.1016/j.supflu.2024.106475","DOIUrl":null,"url":null,"abstract":"Enhanced oil recovery (EOR) involves several techniques, including the injection of gas (such as natural gas, nitrogen, or <mml:math altimg=\"si86.svg\" display=\"inline\"><mml:msub><mml:mrow><mml:mi mathvariant=\"normal\">CO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>) into the reservoir to increase its pressure, thereby displacing oil from one or more injection wells to production wells. For this process to be effective, it is essential that the injected gas and the oil reach a homogeneous state. Particularly, the First-Contact Minimum Miscibility Pressure (FC-MMP) offers a reliable (and safe) initial estimate for the pressure at which the EOR process should be conducted. In this work, an efficient algorithm is developed that allows computing complete pressure(P)-<mml:math altimg=\"si2.svg\" display=\"inline\"><mml:mi>α</mml:mi></mml:math> diagrams (<mml:math altimg=\"si2.svg\" display=\"inline\"><mml:mi>α</mml:mi></mml:math>: percentage of injected gas) at a fixed temperature using traditional cubic equations of state (EoS), including complex cases with three-phase regions. This algorithm is used to study both the qualitative and quantitative behaviour of the P-<mml:math altimg=\"si2.svg\" display=\"inline\"><mml:mi>α</mml:mi></mml:math> diagrams and to analyse how FC-MMP changes with the injection of different gases or gas mixtures. Various reservoir fluids from the literature (with and without asphaltenes and with varying levels of <mml:math altimg=\"si86.svg\" display=\"inline\"><mml:msub><mml:mrow><mml:mi mathvariant=\"normal\">CO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math> and methane) are evaluated. In one section, three injection gases are used: <mml:math altimg=\"si86.svg\" display=\"inline\"><mml:msub><mml:mrow><mml:mi mathvariant=\"normal\">CO</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>, <mml:math altimg=\"si75.svg\" display=\"inline\"><mml:msub><mml:mrow><mml:mi mathvariant=\"normal\">N</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:math>, and a synthetic natural gas mixture, comparing their effects on the P-<mml:math altimg=\"si2.svg\" display=\"inline\"><mml:mi>α</mml:mi></mml:math> diagrams. Then, the impact of interaction parameters on phase equilibrium and FC-MMP is analysed, and the role of asphaltene precipitation is discussed. The study concludes with a quantitative comparison between the FC-MMP calculated here and the Multiple-Contact MMP (MC-MMP) reported for the same fluids. Additionally, the problem of whether asphaltenes precipitation should be considered or ignored in the determination of the FC-MMP is analysed and discussed, with different perspectives for conventional and non-conventional shale type reservoirs.","PeriodicalId":17078,"journal":{"name":"Journal of Supercritical Fluids","volume":"18 1","pages":""},"PeriodicalIF":3.4000,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Supercritical Fluids","FirstCategoryId":"5","ListUrlMain":"https://doi.org/10.1016/j.supflu.2024.106475","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
Enhanced oil recovery (EOR) involves several techniques, including the injection of gas (such as natural gas, nitrogen, or CO2) into the reservoir to increase its pressure, thereby displacing oil from one or more injection wells to production wells. For this process to be effective, it is essential that the injected gas and the oil reach a homogeneous state. Particularly, the First-Contact Minimum Miscibility Pressure (FC-MMP) offers a reliable (and safe) initial estimate for the pressure at which the EOR process should be conducted. In this work, an efficient algorithm is developed that allows computing complete pressure(P)-α diagrams (α: percentage of injected gas) at a fixed temperature using traditional cubic equations of state (EoS), including complex cases with three-phase regions. This algorithm is used to study both the qualitative and quantitative behaviour of the P-α diagrams and to analyse how FC-MMP changes with the injection of different gases or gas mixtures. Various reservoir fluids from the literature (with and without asphaltenes and with varying levels of CO2 and methane) are evaluated. In one section, three injection gases are used: CO2, N2, and a synthetic natural gas mixture, comparing their effects on the P-α diagrams. Then, the impact of interaction parameters on phase equilibrium and FC-MMP is analysed, and the role of asphaltene precipitation is discussed. The study concludes with a quantitative comparison between the FC-MMP calculated here and the Multiple-Contact MMP (MC-MMP) reported for the same fluids. Additionally, the problem of whether asphaltenes precipitation should be considered or ignored in the determination of the FC-MMP is analysed and discussed, with different perspectives for conventional and non-conventional shale type reservoirs.
期刊介绍:
The Journal of Supercritical Fluids is an international journal devoted to the fundamental and applied aspects of supercritical fluids and processes. Its aim is to provide a focused platform for academic and industrial researchers to report their findings and to have ready access to the advances in this rapidly growing field. Its coverage is multidisciplinary and includes both basic and applied topics.
Thermodynamics and phase equilibria, reaction kinetics and rate processes, thermal and transport properties, and all topics related to processing such as separations (extraction, fractionation, purification, chromatography) nucleation and impregnation are within the scope. Accounts of specific engineering applications such as those encountered in food, fuel, natural products, minerals, pharmaceuticals and polymer industries are included. Topics related to high pressure equipment design, analytical techniques, sensors, and process control methodologies are also within the scope of the journal.