Propagation pattern of cracks around a shale borehole via the cohesive element method

Abstract Shale gas is a cutting edge energy source for development, and reserves are abundant. However, shale microcracks develop and tend to form macroscopic fractures during drilling, which can cause severe wellbore instability. Therefore, in combination with rock mechanics theory and fracture mec...

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Main Author: Dexu Sun
Format: Article
Language:English
Published: SpringerOpen 2025-01-01
Series:Journal of Petroleum Exploration and Production Technology
Subjects:
Online Access:https://doi.org/10.1007/s13202-024-01893-6
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author Dexu Sun
author_facet Dexu Sun
author_sort Dexu Sun
collection DOAJ
description Abstract Shale gas is a cutting edge energy source for development, and reserves are abundant. However, shale microcracks develop and tend to form macroscopic fractures during drilling, which can cause severe wellbore instability. Therefore, in combination with rock mechanics theory and fracture mechanics theory, the cohesive element method is adopted to establish a numerical model for differential crack propagation due to bottomhole pressure on the basis of the B-K fracture criterion. The propagation pattern of cracks around a wellbore is simulated, and the influences of rock mechanical parameters, the initial crack length, the direction of crack distribution, and minimum horizontal stress on crack propagation are analyzed. The research results indicate that the larger the Young’s modulus of shale is, the easier it is for cracks to propagate. The Poisson’s ratio of shale has a large influence on crack widening, but its effect on the crack length is weak. The larger the angle between the crack and the maximum horizontal stress is, the more difficult it is for the crack to propagate. The greater the minimum horizontal stress is, the more difficult it is for cracks to propagate. The initial crack length has a weak effect on crack propagation.
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institution Kabale University
issn 2190-0558
2190-0566
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publishDate 2025-01-01
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series Journal of Petroleum Exploration and Production Technology
spelling doaj-art-8922abb5481344ec8e4726892158cf4c2025-02-09T12:13:30ZengSpringerOpenJournal of Petroleum Exploration and Production Technology2190-05582190-05662025-01-0115111310.1007/s13202-024-01893-6Propagation pattern of cracks around a shale borehole via the cohesive element methodDexu Sun0Binnan Oil Production Plant of Shengli Oilfield BranchAbstract Shale gas is a cutting edge energy source for development, and reserves are abundant. However, shale microcracks develop and tend to form macroscopic fractures during drilling, which can cause severe wellbore instability. Therefore, in combination with rock mechanics theory and fracture mechanics theory, the cohesive element method is adopted to establish a numerical model for differential crack propagation due to bottomhole pressure on the basis of the B-K fracture criterion. The propagation pattern of cracks around a wellbore is simulated, and the influences of rock mechanical parameters, the initial crack length, the direction of crack distribution, and minimum horizontal stress on crack propagation are analyzed. The research results indicate that the larger the Young’s modulus of shale is, the easier it is for cracks to propagate. The Poisson’s ratio of shale has a large influence on crack widening, but its effect on the crack length is weak. The larger the angle between the crack and the maximum horizontal stress is, the more difficult it is for the crack to propagate. The greater the minimum horizontal stress is, the more difficult it is for cracks to propagate. The initial crack length has a weak effect on crack propagation.https://doi.org/10.1007/s13202-024-01893-6Wellbore instabilityCohesive unitCrack propagationShale
spellingShingle Dexu Sun
Propagation pattern of cracks around a shale borehole via the cohesive element method
Journal of Petroleum Exploration and Production Technology
Wellbore instability
Cohesive unit
Crack propagation
Shale
title Propagation pattern of cracks around a shale borehole via the cohesive element method
title_full Propagation pattern of cracks around a shale borehole via the cohesive element method
title_fullStr Propagation pattern of cracks around a shale borehole via the cohesive element method
title_full_unstemmed Propagation pattern of cracks around a shale borehole via the cohesive element method
title_short Propagation pattern of cracks around a shale borehole via the cohesive element method
title_sort propagation pattern of cracks around a shale borehole via the cohesive element method
topic Wellbore instability
Cohesive unit
Crack propagation
Shale
url https://doi.org/10.1007/s13202-024-01893-6
work_keys_str_mv AT dexusun propagationpatternofcracksaroundashaleboreholeviathecohesiveelementmethod