Evaluation of Miscible CO₂ Injection and Water-Alternating-CO₂ Injection for Enhanced Oil Recovery in an Algerian Triassic Reservoir

Evaluation of Miscible CO₂ Injection and Water-Alternating-CO₂ Injection for Enhanced Oil Recovery in an Algerian Triassic Reservoir | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Evaluation of Miscible CO₂ Injection and Water-Alternating-CO₂ Injection for Enhanced Oil Recovery in an Algerian Triassic Reservoir Karima HAMMADI, Souhila BOUAZIZ-TERRACHET2, Fahim HAMIDOUCHE This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9394979/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Carbon dioxide (CO₂) injection is widely recognized in the petroleum industry as an effective enhanced oil recovery (EOR) technique and has attracted increasing attention because of its potential role in carbon capture and storage (CCS). This study evaluates and compares two CO₂-based EOR strategies, namely continuous miscible CO₂ injection and water-alternating-CO₂ (WA-CO₂) injection, in a Triassic TAGI reservoir in Algeria. Conventional water flooding and immiscible gas injection were also evaluated to provide a broader assessment of reservoir performance under different development scenarios.The minimum miscibility pressure (MMP) was estimated using several empirical correlations, while reservoir fluid behavior was characterized using the Peng–Robinson equation of state (PR-EOS). A compositional reservoir simulation model was then developed to evaluate oil recovery, pressure evolution, sweep efficiency, and CO₂ retention for each injection scenario.The results indicate that continuous miscible CO₂ injection achieved the highest oil recovery factor, reaching 8.1%, whereas WA-CO₂ injection achieved a slightly lower recovery factor of 7.9%. However, WA-CO₂ injection improved sweep efficiency, reduced gas channeling, and enhanced CO₂ retention within the reservoir. The evaluated Triassic reservoir exhibited favorable conditions for miscible CO₂ flooding, with reservoir pressure exceeding the predicted MMP values by 54% to 81%.This study provides an integrated evaluation of MMP screening, EOS fluid characterization, and compositional simulation to compare miscible CO₂ injection and WA-CO₂ injection in an Algerian Triassic reservoir, which remains insufficiently studied in the literature. The results indicate that continuous miscible CO₂ injection is preferable when maximizing oil recovery is the primary objective, whereas WA-CO₂ injection offers a more balanced approach for improving sweep efficiency and long-term CO₂ storage. CO₂ flooding water-alternating-CO₂ (WA-CO₂) minimum miscibility pressure (MMP) Peng–Robinson equation of state reservoir simulation Triassic reservoirs Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9394979","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":625808098,"identity":"220875ca-f21a-443b-b9cf-80e47de09226","order_by":0,"name":"Karima HAMMADI","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABFklEQVRIiWNgGAWjYBACCQYeMM3Yxt7AwJAARiDABiISCGjhOUCqlgYJiALCWiQbeA9+upljJ9sn+cbswcM2hjx+iezExxVlNvYM7OkPsGmRZuBLls7dlmzcJp1jbpDYxlAsOSN3s+GZc2mJDTwPsFojx8BjANTCnAjUYiaRcOZ/4oYbudskG9sOJzBIJBzAocX4d+62+sQ2yTMgLQwgLdt/Nrb9t2eQSGzA7jAeM6AthxPbJHiAWirAWrYxNrYdAAZIMnbvN/OYWeduO27cxpNWBtJSLNnzdrNkw7nkxDaeZ1i1SBzvMb6du61adn774W2SPwyAIcaeu/FjQ5mdPT+OEGNgxioKAmw4ZUbBKBgFo2AUEAIAOmdclXF3X0AAAAAASUVORK5CYII=","orcid":"","institution":"University of M’hamed Bougara of Boumerdes,","correspondingAuthor":true,"prefix":"","firstName":"Karima","middleName":"","lastName":"HAMMADI","suffix":""},{"id":625808102,"identity":"11ace343-9adc-465b-9fc2-e4a4355d2cd2","order_by":1,"name":"Souhila BOUAZIZ-TERRACHET2","email":"","orcid":"","institution":"University of M’hamed Bougara of Boumerdes","correspondingAuthor":false,"prefix":"","firstName":"Souhila","middleName":"","lastName":"BOUAZIZ-TERRACHET2","suffix":""},{"id":625808104,"identity":"65f418d9-c1e0-4a0f-b640-d4aae65ab1fc","order_by":2,"name":"Fahim HAMIDOUCHE","email":"","orcid":"","institution":"University of M’hamed Bougara of Boumerdes,","correspondingAuthor":false,"prefix":"","firstName":"Fahim","middleName":"","lastName":"HAMIDOUCHE","suffix":""}],"badges":[],"createdAt":"2026-04-12 14:38:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9394979/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9394979/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108907506,"identity":"1dc4f461-a071-4ff0-a262-9dc0afa7e8e0","added_by":"auto","created_at":"2026-05-10 11:40:52","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1578086,"visible":true,"origin":"","legend":"","description":"","filename":"MiscibleCO2V2.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9394979/v1_covered_56574bdd-234c-4365-9027-c651d0464ff1.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Evaluation of Miscible CO₂ Injection and Water-Alternating-CO₂ Injection for Enhanced Oil Recovery in an Algerian Triassic Reservoir","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"CO₂ flooding, water-alternating-CO₂ (WA-CO₂), minimum miscibility pressure (MMP), Peng–Robinson equation of state, reservoir simulation, Triassic reservoirs","lastPublishedDoi":"10.21203/rs.3.rs-9394979/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9394979/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Carbon dioxide (CO₂) injection is widely recognized in the petroleum industry as an effective enhanced oil recovery (EOR) technique and has attracted increasing attention because of its potential role in carbon capture and storage (CCS). This study evaluates and compares two CO₂-based EOR strategies, namely continuous miscible CO₂ injection and water-alternating-CO₂ (WA-CO₂) injection, in a Triassic TAGI reservoir in Algeria. Conventional water flooding and immiscible gas injection were also evaluated to provide a broader assessment of reservoir performance under different development scenarios.The minimum miscibility pressure (MMP) was estimated using several empirical correlations, while reservoir fluid behavior was characterized using the Peng–Robinson equation of state (PR-EOS). A compositional reservoir simulation model was then developed to evaluate oil recovery, pressure evolution, sweep efficiency, and CO₂ retention for each injection scenario.The results indicate that continuous miscible CO₂ injection achieved the highest oil recovery factor, reaching 8.1%, whereas WA-CO₂ injection achieved a slightly lower recovery factor of 7.9%. However, WA-CO₂ injection improved sweep efficiency, reduced gas channeling, and enhanced CO₂ retention within the reservoir. The evaluated Triassic reservoir exhibited favorable conditions for miscible CO₂ flooding, with reservoir pressure exceeding the predicted MMP values by 54% to 81%.This study provides an integrated evaluation of MMP screening, EOS fluid characterization, and compositional simulation to compare miscible CO₂ injection and WA-CO₂ injection in an Algerian Triassic reservoir, which remains insufficiently studied in the literature. 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