Analytical Model of Wellbore Stability of Fractured Coal Seam Considering the Effect of Cleat Filler and Analysis of Influencing Factors
Currently, coal borehole collapses frequently occur during drilling. Considering that the coal near to the wellbore is cut into blocks, and the cleat filler of the coal influences the stress distribution near the wellbore, a new theoretical solution of a near-wellbore Stress Field in coal bed wells...
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MDPI AG
2020-02-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/10/3/1169 |
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| author | Xinbo Zhao Jianjun Wang Yue Mei |
| author_facet | Xinbo Zhao Jianjun Wang Yue Mei |
| author_sort | Xinbo Zhao |
| collection | DOAJ |
| description | Currently, coal borehole collapses frequently occur during drilling. Considering that the coal near to the wellbore is cut into blocks, and the cleat filler of the coal influences the stress distribution near the wellbore, a new theoretical solution of a near-wellbore Stress Field in coal bed wells is established. In addition, according to the limit equilibrium theory and the E.MG-C criterion, the limit sliding formula of the quadrilateral and triangular block is deduced, and the slipping direction of the blocks is further judged. Finally, the wellbore stability model of the coal seam is established. The accuracy of the theoretical model is verified through a numerical method by using the PFC software. Based upon this wellbore stability theoretical model of coal, many cleat affecting factors such as cleat spacing, cleat length, cleat angle and the cleat geometric position, are studied, and the results show that a quadrilateral block slides off more easily than a triangular block under the same boundary condition; the bigger the cleat spacing and cleat length are, the lower is the risk that blocks slide off, and increasing the cleat angle could cause blocks to slide off easily. Under the same boundary condition, whether blocks slide off or not is closely related to the well round angle. |
| first_indexed | 2024-12-10T05:06:44Z |
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| id | doaj.art-d3490154b3b8453a93c0fea8c1347454 |
| institution | Directory Open Access Journal |
| issn | 2076-3417 |
| language | English |
| last_indexed | 2024-12-10T05:06:44Z |
| publishDate | 2020-02-01 |
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| spelling | doaj.art-d3490154b3b8453a93c0fea8c13474542022-12-22T02:01:14ZengMDPI AGApplied Sciences2076-34172020-02-01103116910.3390/app10031169app10031169Analytical Model of Wellbore Stability of Fractured Coal Seam Considering the Effect of Cleat Filler and Analysis of Influencing FactorsXinbo Zhao0Jianjun Wang1Yue Mei2School of Science, Qingdao University of Technology, Qingdao 266033, ChinaState Key Laboratory for Performance and Structure Safety of Petroleum Tubular Goods and Equipment Materials, CNPC TubularGoods Research Center, Xian 710077, ChinaState Key Laboratory of Structural Analysis for Industrial Equipment, Department of Engineering Mechanics, Dalian University of Technology, Dalian 116023, ChinaCurrently, coal borehole collapses frequently occur during drilling. Considering that the coal near to the wellbore is cut into blocks, and the cleat filler of the coal influences the stress distribution near the wellbore, a new theoretical solution of a near-wellbore Stress Field in coal bed wells is established. In addition, according to the limit equilibrium theory and the E.MG-C criterion, the limit sliding formula of the quadrilateral and triangular block is deduced, and the slipping direction of the blocks is further judged. Finally, the wellbore stability model of the coal seam is established. The accuracy of the theoretical model is verified through a numerical method by using the PFC software. Based upon this wellbore stability theoretical model of coal, many cleat affecting factors such as cleat spacing, cleat length, cleat angle and the cleat geometric position, are studied, and the results show that a quadrilateral block slides off more easily than a triangular block under the same boundary condition; the bigger the cleat spacing and cleat length are, the lower is the risk that blocks slide off, and increasing the cleat angle could cause blocks to slide off easily. Under the same boundary condition, whether blocks slide off or not is closely related to the well round angle.https://www.mdpi.com/2076-3417/10/3/1169cleat fillerbroken coal seamwellbore stabilityanalytical modelaffecting factors |
| spellingShingle | Xinbo Zhao Jianjun Wang Yue Mei Analytical Model of Wellbore Stability of Fractured Coal Seam Considering the Effect of Cleat Filler and Analysis of Influencing Factors Applied Sciences cleat filler broken coal seam wellbore stability analytical model affecting factors |
| title | Analytical Model of Wellbore Stability of Fractured Coal Seam Considering the Effect of Cleat Filler and Analysis of Influencing Factors |
| title_full | Analytical Model of Wellbore Stability of Fractured Coal Seam Considering the Effect of Cleat Filler and Analysis of Influencing Factors |
| title_fullStr | Analytical Model of Wellbore Stability of Fractured Coal Seam Considering the Effect of Cleat Filler and Analysis of Influencing Factors |
| title_full_unstemmed | Analytical Model of Wellbore Stability of Fractured Coal Seam Considering the Effect of Cleat Filler and Analysis of Influencing Factors |
| title_short | Analytical Model of Wellbore Stability of Fractured Coal Seam Considering the Effect of Cleat Filler and Analysis of Influencing Factors |
| title_sort | analytical model of wellbore stability of fractured coal seam considering the effect of cleat filler and analysis of influencing factors |
| topic | cleat filler broken coal seam wellbore stability analytical model affecting factors |
| url | https://www.mdpi.com/2076-3417/10/3/1169 |
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