Numerical Simulation on the Influence of the Distribution Characteristics of Cracks and Solution Cavities on the Wellbore Stability in Carbonate Formation

The development of cracks and solution cavities in carbonate reservoirs can notably reduce the rock’s mechanical properties, leading to a severe wellbore collapse problem during drilling operations. To clarify the influence of the characteristics of cracks and solution cavities on the wellbore stabi...

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Main Authors: Jingzhe Zhang, Rongrong Zhao, Hongyi An, Wenhao Li, Yuxin Geng, Xiangyu Fan, Qiangui Zhang
Format: Article
Language:English
Published: MDPI AG 2024-11-01
Series:Applied Sciences
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Online Access:https://www.mdpi.com/2076-3417/14/22/10099
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author Jingzhe Zhang
Rongrong Zhao
Hongyi An
Wenhao Li
Yuxin Geng
Xiangyu Fan
Qiangui Zhang
author_facet Jingzhe Zhang
Rongrong Zhao
Hongyi An
Wenhao Li
Yuxin Geng
Xiangyu Fan
Qiangui Zhang
author_sort Jingzhe Zhang
collection DOAJ
description The development of cracks and solution cavities in carbonate reservoirs can notably reduce the rock’s mechanical properties, leading to a severe wellbore collapse problem during drilling operations. To clarify the influence of the characteristics of cracks and solution cavities on the wellbore stability in the Dengying Formation carbonate reservoir in the Gaoshiti–Moxi area of Sichuan, the mechanical properties of carbonate rock were analyzed. Then, the influences of the attitude and width of cracks, the size and quantity of solution cavities, and their connectivity on wellbore stability were studied using FLAC3D 6.00 numerical simulation software. Our results show the following: (1) The cracks and solution cavities in the Dengying Formation carbonate rock cause significant differences in the rock’s mechanical properties. (2) The equivalent drilling fluid density of collapse pressure (<i>ρ</i><sub>c</sub>) considering the effects of cracks and solution cavities is 6.4% higher than without these effects, which is in good accordance with engineering practice. Additionally, cracks play a more significant role than solution cavities in affecting the wellbore stability. (3) When the orientation of a crack is closer to the direction of maximum horizontal stress, and the dip angle and width of the crack increase, the stress and deformation at the intersection of the crack and wellbore gradually increase, and correspondingly, <i>ρ</i><sub>c</sub> also increases. (4) The stress and displacement of various points around the solution cavities gradually increase with the increases in diameter and quantity of solution cavities, and <i>ρ</i><sub>c</sub> also increases. (5) Compared with the situation where cracks and solution cavities are not interconnected, the stress disturbance area around the wellbore is larger, and <i>ρ</i><sub>c</sub> is greater when cracks and solution cavities are interconnected.
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spelling doaj-art-b6b06c5f0f5a41c2b3c360ebcbec0e9c2025-08-20T02:08:07ZengMDPI AGApplied Sciences2076-34172024-11-0114221009910.3390/app142210099Numerical Simulation on the Influence of the Distribution Characteristics of Cracks and Solution Cavities on the Wellbore Stability in Carbonate FormationJingzhe Zhang0Rongrong Zhao1Hongyi An2Wenhao Li3Yuxin Geng4Xiangyu Fan5Qiangui Zhang6Exploration Utility Department, CNPC Southwest Oil and Gas Field Company, Chengdu 610095, ChinaExploration Utility Department, CNPC Southwest Oil and Gas Field Company, Chengdu 610095, ChinaExploration Utility Department, CNPC Southwest Oil and Gas Field Company, Chengdu 610095, ChinaExploration Utility Department, CNPC Southwest Oil and Gas Field Company, Chengdu 610095, ChinaShanxi CBM Exploration and Development, CNPC Huabei Oil Field Company, Changzhi 046000, ChinaSchool of Geoscience and Technology, Southwest Petroleum University, Chengdu 610500, ChinaPetroleum Engineering School, Southwest Petroleum University, Chengdu 610500, ChinaThe development of cracks and solution cavities in carbonate reservoirs can notably reduce the rock’s mechanical properties, leading to a severe wellbore collapse problem during drilling operations. To clarify the influence of the characteristics of cracks and solution cavities on the wellbore stability in the Dengying Formation carbonate reservoir in the Gaoshiti–Moxi area of Sichuan, the mechanical properties of carbonate rock were analyzed. Then, the influences of the attitude and width of cracks, the size and quantity of solution cavities, and their connectivity on wellbore stability were studied using FLAC3D 6.00 numerical simulation software. Our results show the following: (1) The cracks and solution cavities in the Dengying Formation carbonate rock cause significant differences in the rock’s mechanical properties. (2) The equivalent drilling fluid density of collapse pressure (<i>ρ</i><sub>c</sub>) considering the effects of cracks and solution cavities is 6.4% higher than without these effects, which is in good accordance with engineering practice. Additionally, cracks play a more significant role than solution cavities in affecting the wellbore stability. (3) When the orientation of a crack is closer to the direction of maximum horizontal stress, and the dip angle and width of the crack increase, the stress and deformation at the intersection of the crack and wellbore gradually increase, and correspondingly, <i>ρ</i><sub>c</sub> also increases. (4) The stress and displacement of various points around the solution cavities gradually increase with the increases in diameter and quantity of solution cavities, and <i>ρ</i><sub>c</sub> also increases. (5) Compared with the situation where cracks and solution cavities are not interconnected, the stress disturbance area around the wellbore is larger, and <i>ρ</i><sub>c</sub> is greater when cracks and solution cavities are interconnected.https://www.mdpi.com/2076-3417/14/22/10099wellbore stabilitydengying formationcarbonate rockscracks and solution cavities characteristicsnumerical simulation
spellingShingle Jingzhe Zhang
Rongrong Zhao
Hongyi An
Wenhao Li
Yuxin Geng
Xiangyu Fan
Qiangui Zhang
Numerical Simulation on the Influence of the Distribution Characteristics of Cracks and Solution Cavities on the Wellbore Stability in Carbonate Formation
Applied Sciences
wellbore stability
dengying formation
carbonate rocks
cracks and solution cavities characteristics
numerical simulation
title Numerical Simulation on the Influence of the Distribution Characteristics of Cracks and Solution Cavities on the Wellbore Stability in Carbonate Formation
title_full Numerical Simulation on the Influence of the Distribution Characteristics of Cracks and Solution Cavities on the Wellbore Stability in Carbonate Formation
title_fullStr Numerical Simulation on the Influence of the Distribution Characteristics of Cracks and Solution Cavities on the Wellbore Stability in Carbonate Formation
title_full_unstemmed Numerical Simulation on the Influence of the Distribution Characteristics of Cracks and Solution Cavities on the Wellbore Stability in Carbonate Formation
title_short Numerical Simulation on the Influence of the Distribution Characteristics of Cracks and Solution Cavities on the Wellbore Stability in Carbonate Formation
title_sort numerical simulation on the influence of the distribution characteristics of cracks and solution cavities on the wellbore stability in carbonate formation
topic wellbore stability
dengying formation
carbonate rocks
cracks and solution cavities characteristics
numerical simulation
url https://www.mdpi.com/2076-3417/14/22/10099
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