Numerical simulation study on sweet spot identification and parameter optimization of refractured horizontal wells in ultra-low permeability reservoirs

Numerical simulation study on sweet spot identification and parameter optimization of refractured horizontal wells in ultra-low permeability reservoirs | 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 Numerical simulation study on sweet spot identification and parameter optimization of refractured horizontal wells in ultra-low permeability reservoirs Jian Sun, Zhe Zhang, Le Qu, Yong Ai, Rongjun Zhang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7331144/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 Non-uniform production contribution caused by insufficient reservoir stimulation during initial fracturing significantly constrains well lifecycle and economic ultimate recovery (EUR). Refracturing is urgently required to reconstruct fracture networks and activate undeveloped reserve zones. An geomechanics-matrix-fracture-seepage coupling model is developed using the Unconventional Fracturing Model (UFM), which can revealing formation energy evolution and residual oil distribution characteristics after hydraulic fracturing in ultra-low permeability reservoirs. Building on this foundation, key re-fracturing technologies and parameter optimization are investigated. The study indicates that after the initial fracturing, energy diffusion is limited, and water injection primarily enhances energy near fractures, failing to establish an effective reservoir displacement system and resulting in inefficient residual oil utilization. A ‘Re-pressurization of existing fractures + inter-stage new fracture stimulation’ strategy is implemented to enhance stimulated reservoir efficiency of complex fracture networks. By focusing on fracture half-length, discharge rate parameters are optimized during fracturing to maximize the stimulated volume within the target sweet spot. For multi-stage clustered perforated horizontal wells, proppant and fluid injection volumes are optimized while ensuring adequate fracture conductivity. This study provides theoretical guidance for sweet spot evaluation and parameter optimization in re-fracturing of ultra-low permeability horizontal wells. Ultra-low permeability reservoir Refracture Unconventional Fracturing Model Fracture propagation Fracturing sweet spot 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. 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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-7331144","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":561855009,"identity":"ef595747-89ba-4466-b65f-0b395f1a124f","order_by":0,"name":"Jian Sun","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAwUlEQVRIie3QIQ7CQBBA0WlIBkNauwRCr7ANF+Aos0FU4SsQxWwNZ+AY6G1IpqYHIMH0CJUVFWy5QAdHwn4xWTFPzAKEQj8ZA3SAO1xW7gtCgPt41ZKU4ETA3NRBy4Cu2XQ0xrlVXg7FfZ6sS35oY/FkNxcXXdvXPEmgscqUnmwdLSIrIAhNNdCIOSrSMpIAMxAiyYm/5aj8LZn1n1yLbtFPzvp+5DStqrobCgEB5abJn7cT7PuScppn2XIoFAr9Z289zT3dKop7CAAAAABJRU5ErkJggg==","orcid":"","institution":"Xi’an Shiyou University","correspondingAuthor":true,"prefix":"","firstName":"Jian","middleName":"","lastName":"Sun","suffix":""},{"id":561855010,"identity":"91a8985c-fd6d-47fb-9ceb-c03679f63b4c","order_by":1,"name":"Zhe Zhang","email":"","orcid":"","institution":"Xi’an Shiyou University","correspondingAuthor":false,"prefix":"","firstName":"Zhe","middleName":"","lastName":"Zhang","suffix":""},{"id":561855011,"identity":"7a1033aa-7d98-4de4-9daa-ca362e0f05fe","order_by":2,"name":"Le Qu","email":"","orcid":"","institution":"Xi’an Shiyou University","correspondingAuthor":false,"prefix":"","firstName":"Le","middleName":"","lastName":"Qu","suffix":""},{"id":561855015,"identity":"810b6a50-489a-49a8-8bb2-ddad84419657","order_by":3,"name":"Yong Ai","email":"","orcid":"","institution":"Tarim Oilfield Company, Petro China","correspondingAuthor":false,"prefix":"","firstName":"Yong","middleName":"","lastName":"Ai","suffix":""},{"id":561855017,"identity":"25b927b0-de70-4526-8ffe-636bcc7a192d","order_by":4,"name":"Rongjun Zhang","email":"","orcid":"","institution":"Xi’an Shiyou University","correspondingAuthor":false,"prefix":"","firstName":"Rongjun","middleName":"","lastName":"Zhang","suffix":""}],"badges":[],"createdAt":"2025-08-09 04:08:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-7331144/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-7331144/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101205268,"identity":"9ed66121-598f-485b-a7da-266a250d410d","added_by":"auto","created_at":"2026-01-27 09:48:47","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1769577,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7331144/v1_covered_9f5655f1-e962-427e-bb9c-f6afddd25cc1.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Numerical simulation study on sweet spot identification and parameter optimization of refractured horizontal wells in ultra-low permeability reservoirs","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":"Ultra-low permeability reservoir, Refracture, Unconventional Fracturing Model, Fracture propagation, Fracturing sweet spot","lastPublishedDoi":"10.21203/rs.3.rs-7331144/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7331144/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"Non-uniform production contribution caused by insufficient reservoir stimulation during initial fracturing significantly constrains well lifecycle and economic ultimate recovery (EUR). Refracturing is urgently required to reconstruct fracture networks and activate undeveloped reserve zones. An geomechanics-matrix-fracture-seepage coupling model is developed using the Unconventional Fracturing Model (UFM), which can revealing formation energy evolution and residual oil distribution characteristics after hydraulic fracturing in ultra-low permeability reservoirs. Building on this foundation, key re-fracturing technologies and parameter optimization are investigated. The study indicates that after the initial fracturing, energy diffusion is limited, and water injection primarily enhances energy near fractures, failing to establish an effective reservoir displacement system and resulting in inefficient residual oil utilization. A ‘Re-pressurization of existing fractures + inter-stage new fracture stimulation’ strategy is implemented to enhance stimulated reservoir efficiency of complex fracture networks. 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