钻井液滤失对煤岩井壁稳定性的影响
Study on the influence of drilling fluid filtration on stability of coalbed wellbore
-
摘要: 煤岩具有割理、孔隙等多孔特性,钻井液易侵入,导致井壁围岩失稳。考虑钻井液滤失对煤岩的物理作用,以Mohr-Coulomb塑性模型为煤岩破坏准则,建立了煤岩井壁稳定评价的流固耦合模型,通过数值模拟,对比分析了钻井液滤失对煤岩应力场和渗流场的影响。结果表明:不均匀地应力的挤压作用使钻井液容易沿着最大水平地应力方向滤失;而钻井液滤失会导致孔隙压力增大,继而使井壁煤岩的应力发生改变,应力场最大值由最大水平地应力方向转移到了最小水平地应力方向,且应力极值由15 MPa增至17 MPa,不利于煤岩稳定;在正向压差条件下,钻井液会侵入煤岩孔隙,使孔隙压力增大,导致煤岩应力增大,引起煤岩失稳;因此,钻井液密度设计时应综合考虑井筒液柱支撑井壁和孔隙增压破坏井壁的影响。
Abstract: Coal rock has many porous characteristics, such as cleavage, pore and so on. Drilling fluid is easy to invade into coal bed rock, which is easy to cause wellbore instability. Considering the physical effect of drilling fluid loss on coal rock, a fluid-solid coupling model for evaluating the stability of coal wellbore is established by using Mohr-Coulomb plastic model as the failure criterion of coal bed rock. Through numerical simulation, the effects of drilling fluid loss on the stress field and seepage field of coal rock are compared and analyzed. The results show that the extrusion of non-uniform in-situ stress makes drilling fluid easy to leak along the direction of maximum horizontal in-situ stress, and the loss of drilling fluid will lead to the increase of pore pressure, which will change the stress of coal rock surrounding the wellbore. The maximum stress field shifts from the direction of maximum horizontal in-situ stress to the direction of minimum horizontal in-situ stress, and the maximum stress increases from 15 MPa to 17 MPa, which is not conducive to the stability of coal rock. Under the condition of positive pressure difference, drilling fluid will invade into the pore of coal rock, increase the pore pressure, cause the stress of coal and rock to increase, and cause wellbore instability. Therefore, the influence of drilling fluid pressure supporting wellbore and pore pressurization to damage wellbore should be considered comprehensively in the design of drilling fluid density.
-
-
[1] Akbarpour M, and M Abdideh. Wellbore stability analysis based on geomechanical modeling using finite element method[J]. Modeling Earth Systems and Environment, 2020, 6(3/4): 617-22. [2] Aslannezhad M, Keshavarz A, Kalantariasl A. Evaluation of mechanical, chemical, and thermal effects on wellbore stability using different rock failure criteria [J]. Journal of Natural Gas Science and Engineering, 2020, 78(1): 1-16. [3] 张遂安,袁玉,孟凡圆.我国煤层气开发技术进展 [J]. 煤炭科学技术,2016,44(5):1-5. ZHANG Suian, YUAN Yu, MENG Fanguo. Progress on coalbed methoane development technology in China [J]. Coal Science and Technology, 2016, 44 (5): 1-5.
[4] Zheng L H, Su G D, Li Z H, et al. The wellbore instability control mechanism of fuzzy ball drilling fluids for coal bed methane wells via bonding formation[J]. Journal of Natural Gas Science and Engineering, 2018, 56: 107-120. [5] 申瑞臣,屈平,杨恒林.煤层井壁稳定技术研究进展与发展趋势[J].石油钻探技术,2010,38(3):1-7. SHEN Ruichen, QU Ping, YANG Henglin. Advancement and development of coal bed wellbore stability technology[J]. Petroleum Drilling Techniques, 2010, 38(3): 1-7.
[6] 魏凯,管志川,廖华林,等.井壁失稳风险评价方法 [J]. 中国石油大学学报(自然科学版),2013,37(2):62-66. WEI Kai, GUAN Zhichuan, LIAO Hualin, et cal. Assessment method of borehole instability risk[J]. Journal of China University of Petroleum, 2013, 37(2): 62-66.
[7] 冯立杰,江涛,岳俊举,等.煤层气开采钻井工程关键影响因素识别研究[J].煤矿安全,2018,49(12):177. FENG Lijie, JIANG Tao, YUE Junju, et cl. Identification of key influencing factors of CBM drilling engineering[J]. Safety in Coal Mines, 2018, 49 (12): 177-180.
[8] Gentzis T, Deisman N, Chalaturnyk R J. Effect of drilling fluids on coal permeability: Impact on horizontal wellbore stability[J]. International Journal of Coal Geology, 2009, 78(3): 177-191. [9] 屈平,申瑞臣.煤层气钻井井壁稳定机理及钻井液密度窗口的确定[J].天然气工业,2010,30(10):64-68. QU Ping, SHEN Ruichen. Mechanism of wellbore stability and determination of drilling fluid density window in coalbed methane drilling[J]. Natural Gas Industry, 2010, 30(10): 64-68.
[10] Akbarpour M, Abdideh M. Wellbore stability analysis based on geomechanical modeling using finite element method[J]. Modeling Earth Systems and Environment, 2020, 6(3/4): 617-622. [11] 邓虎,孟英峰.泥页岩稳定性的化学与力学耦合研究综述[J].石油勘探与开发,2003,30(1):109-111. DENG Hu, MENG Yingfeng. A discussion on shale stability coupling with mechanics and chemistry[J]. Petroleum Exploration and Development, 2003, 30(1): 109-111.
[12] 孙正财,刘向君,梁利喜,等.煤层气井割理煤岩井壁稳定性影响因素分析[J].煤炭科学技术,2018,46(4):117-122. SUN Zhengcai, LIU Xiangjun, LIANG Lixi, et al. Analysis on impact factors of borehole wall stability of coalbed methane well[J]. Coal Science and Technology, 2018, 46(4): 117-122.
[13] 何世明,陈俞霖,马德新,等.井壁稳定多场耦合分析研究进展[J].西南石油大学学报(自然科学版),2017(2):81-92. HE Shiming, CHEN Yulin, MA Dexin, et al. A review on wellbore stability with multi-field coupling analysis [J]. Journal of Southwest Petroleum (Science & Technology Edition), 2017(2):81-92.
[14] 和志浩.煤岩井壁稳定性的岩石力学基础研究[D]. 成都:西南石油大学,2013:80-90. [15] 徐献芝,李培超,李传亮.多孔介质有效应力原理研究[J].力学与实践,2001,23(4):42-45. XU Xianzhi, LI Peichao, LI Chuanliang. Principle of effective stress based on porous medium[J]. Mechanics in Engineering, 2001, 23(4): 42-45.
[16] 李培超.多孔介质流-固耦合渗流数学模型研究[J].岩石力学与工程学报,2004,23(16):2842-2842. LI Peichao. Mathematical models of flow-deformation coupling for porous media[J]. Chinese Journal of Rock Mechanics and Engineering, 2004, 23(16): 2842-2842.
[17] 刘鸿文.材料力学(第五版)[M].北京:高等教育出版社,2010:50-56. [18] 谢玉华,赵坤,刘见宝,等.新景矿3号煤层渗透率对有效应力敏感性实验分析[J].煤矿安全,2020,51(4):36-41. XIE Yuhua, ZHAO Kun, LIU Jianbao, et cl. Experimental analysis of sensitivity of permeability to effective stress in No.3 coal seam of Xinjing Coal Mine [J]. Safety in Coal Mines, 2020, 51(4): 36-41.
[19] Louis C. Rock hydraulics in rock mechanics[M]. New York: Springer Verlag, 1974: 299-387. [20] 魏凯,马金山,管志川,等.井壁失稳区域确定方法及影响因素分析[J].力学与实践,2014,36(1):54-58. WEI Kai, MA Jinshan, GUAN Zhichuan, et al. Determination of wellbore instability area and analysis of influencing factors[J]. Mechanics in Engineering, 2014, 36(1): 54-58.
[21] 张丹丹,冯雨实,李永臣,等.基于有限元软件的煤层气水平井井壁稳定数值模拟[J].煤矿安全,2018,49(3):144-147. ZHANG Dandan, FENG Yushi, LI Yongchen, et cl. Numerical simulation of wellbore stability for CBM horizontal well by finite element software[J]. Safety in Coal Mines, 2018, 49 (3): 144-147.
[22] 陈勉,金衍,张光清.石油工程岩石力学[M].北京:科学出版社,2008:80-83. [23] 韩帅,孙达,金珠鹏,等.不同屈服准则下回采巷道区段煤柱的合理宽度[J].煤矿安全,2018,49(2):189. HAN Shuai, SUN Da, JIN Zhupeng, et cl. Reasonable width of sectional coal pillar of mining roadway under different yield criterions[J]. Safety in Coal Mines, 2018, 49(2): 189-193.
计量
- 文章访问数: 33
- HTML全文浏览量: 0
- PDF下载量: 0
下载:
