Rule of Propagation of Fractures through the Bonding Interfaces of Cement Sheath in Horizontal Well Fracturing
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摘要: 页岩气水平井压裂过程中，高压流体的注入可能会引起压裂液沿水泥环一、二界面的窜流，对页岩气井井筒完整性提出了严峻挑战。基于CZM模型建立了定注入压力下水泥环一、二界面裂缝扩展模型，分析了水泥环、地层力学参数对固井界面裂缝扩展的影响规律。研究结果表明：提高固井二界面的胶结强度能同时抑制一、二界面的裂缝扩展；水泥环弹性模量由4 GPa增加至9 GPa，一、二界面扩展长度分别降低10 m、19 m，当弹性模量超过6 GPa时，其对二界面的影响减弱，泊松比由0.2增加至0.3，一、二界面裂缝长度分别降低10 m、1 m，表明泊松比主要会对一界面的裂缝扩展有所影响；地层弹性量从25 GPa增加到35 GPa，一、二界面裂缝长度分别增加3 m、9 m，表明弹性模量较低的地层有助于控制界面裂缝扩展。研究结果对水平井压裂过程中水泥环密封完整性的评价以及水泥浆体系的优选具有一定的指导意义。Abstract: In fracturing a horizontal shale gas well, the injection of a high pressure fluid into the well may cause flow of the fracturing fluid along the interface between the casing and the cement sheath and the interface between the cement sheath and the borehole wall, and this imposes a serious challenge to the borehole integrity. A model describing the extension of fractures on both sides of cement sheath under constant injection pressure was established based on the CZM model, and the effects of cement sheath, formation mechanical parameters on the extension of the fractures on the cement sheath were analyzed. The study shows that increasing the cementing strengths of the two interfaces can simultaneously inhibit the extension of the fractures on both sides of the cement sheath. When the elastic modulus of the cement sheath is increased from 4 GPa to 9 GPa, the lengths of the fracture extension on the side of the cement sheath in contact with casing string and on the side of the cement sheath in contact with borehole wall will be reduced by 10 m and 19 m, respectively. When the elastic modulus exceeds 6 MPa, its effect on fracture extension on the side of the cement sheath in contact with borehole wall is becoming weakened. When the Poisson’s ratio is increased from 0.2 to 0.3, the lengths of the fracture extension on the side of the cement sheath in contact with casing string and on the side of the cement sheath in contact with borehole wall will be reduced by 10 m and 1 m, respectively, meaning that the Poisson’s ratio mainly affects the fracture extension on the side of the cement sheath in contact with casing. On the other hand, when the elastic modulus of the formation is increased from 25 GPa to 35 GPa, the lengths of the fracture extension on the side of the cement sheath in contact with casing string and on the side of the cement sheath in contact with borehole wall will be increased by 3 m and 9 m, respectively, meaning that a formation with low elastic modulus is beneficial to the controlling of the fracture extension. The achievements made in the study is of a certain guiding importance to the evaluation of the sealing integrity of the cement sheath in fracturing a horizontal well, and to the optimization of a cement slurry system.
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Key words:
- Hydraulic fracturing /
- Cement sheath /
- CZM /
- Fracture extension
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表 1 模型几何参数及材料特性
介质 外径/
mm内径/
mm弹性模量/
GPa泊松比 内摩擦角/
（°）黏聚力/
MPa套管 139.7 118.62 210 0.30 水泥环 215.9 139.70 8 0.30 17.1 21.6 地层 35 0.23 30.0 59.3 
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表 3 模型几何参数及材料特性
粒径/
mm弹性剂/
%水泥石抗压
强度/ MPa水泥石弹性
模量/GPa0 33.30 12.44 0.18 2 31.00 9.10 4 24.85 6.46 6 19.32 6.15 8 15.67 4.88
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[1] 薛承瑾. 页岩气压裂技术现状及发展建议[J]. 石油钻探技术,2011,39(3):24-29. doi: 10.3969/j.issn.1001-0890.2011.03.004XUE Chengjin. Technical advance and development proposals of shale gas fracturing[J]. Petroleum Drilling Techniques, 2011, 39(3):24-29. doi: 10.3969/j.issn.1001-0890.2011.03.004 [2] 戴强. 页岩气井完井改造期间生产套管损坏原因初探[J]. 钻采工艺,2015(3):22-25.DAI Qiang. Analysis of production casing damage reasons during testing and completion of shale gas well[J]. Drilling & Production Technology, 2015(3):22-25. [3] 田中兰,石林,乔磊. 页岩气水平井井筒完整性问题及对策[J]. 天然气工业,2015,35(9):70-76. doi: 10.3787/j.issn.1000-0976.2015.09.010TIAN Zhonglan, SHI Lin, QIAO Lei. Research of and countermeasure for wellbore integrity of shale gas horizontal well[J]. Natural Gas Industry, 2015, 35(9):70-76. doi: 10.3787/j.issn.1000-0976.2015.09.010 [4] 范明涛,李军,柳贡慧,等. 页岩气水平井体积压裂过程中套损机理研究[J]. 石油机械,2018,46(4):82-87. doi: 10.16082/j.cnki.issn.1001-4578.2018.04.015FAN Mingtao, LI Jun, LIU Gonghui, et al. Study on casing damage mechanism in volume fracturing of shale gas horizontal well[J]. China Petroleum Machinery, 2018, 46(4):82-87. doi: 10.16082/j.cnki.issn.1001-4578.2018.04.015 [5] 初纬,沈吉云,杨云飞,等. 连续变化内压下套管-水泥环-围岩组合体微环隙计算[J]. 石油勘探与开发,2015,42(3):379-385. doi: 10.1016/S1876-3804(15)30028-8CHU Wei, SHEN Jiyun, YANG Yunfei, et al. Calculation of micro-annulus size in casing-cement sheath-formation system under continuous internal casing pressure change[J]. Petroleum Exploration and Development, 2015, 42(3):379-385. doi: 10.1016/S1876-3804(15)30028-8 [6] 席岩,王海涛,李军,等. 循环载荷对水泥环密封性影响试验与数值研究[J]. 石油机械,2021,49(2):88-93.XI Yan, WANG Haitao, LI Jun, et al. Experimental study and numerical analysis of the influence of cyclic loading on the cement sheath sealing performance[J]. China Petroleum Machinery, 2021, 49(2):88-93. [7] 许红林,张智,施太和,等. 压力和温度共同作用下的水泥环应力分析[J]. 石油钻探技术,2014(6):45-48. doi: 10.11911/syztjs.201406009XU Honglin, ZHANG Zhi, SHI Taihe, et al. Analysis of the cement sheath under both pressure and temperature[J]. Petroleum Drilling Techniques, 2014(6):45-48. doi: 10.11911/syztjs.201406009 [8] 范明涛,李军,柳贡慧. 页岩地层体积压裂过程中水泥环完整性研究[J]. 石油机械,2017,45(8):45-49.FAN Mingtao, LI Jun, LIU Gonghui. Study on cement sheath integrity in shale formation fracturing process[J]. China Petroleum Machinery, 2017, 45(8):45-49. [9] ALBAWI A, DE ANDRADE J, TORSÆTER M, et al. Experimental set-up for testing cement sheath integrity in arctic wells[C]//OTC Arctic Technology Conference. OnePetro, 2014. [10] 舒刚,刘健,冯逢,等. 储气库注采井水泥环破坏机理实验研究[J]. 钻井液与完井液,2020,37(4):507-511,520. doi: 10.3969/j.issn.1001-5620.2020.04.017SHU Gang, LIU Jian, FENG Feng, et al. Experimental study on failure mechanism of cement sheath in injection production well of gas storage[J]. Drilling Fluid & Completion Fluid, 2020, 37(4):507-511,520. doi: 10.3969/j.issn.1001-5620.2020.04.017 [11] 刘仍光,张林海,陶谦,等. 循环应力作用下水泥环密封性实验研究[J]. 钻井液与完井液,2016,33(4):74-78.LIU Rengguang, ZHANG Linhai, TAO Qian, et al. Experimental study on airtightness of cement sheath under alternating stress[J]. Drilling Fluid & Completion Fluid, 2016, 33(4):74-78. [12] TOMAR V, ZHAI J, ZHOU M. Bounds for element size in a variable stiffness cohesive finite element model[J]. International Journal for Numerical Methods in Engineering, 2004, 61(11):1894-1920. doi: 10.1002/nme.1138 [13] CAMANHO P P, DÁVILA C G. Mixed-mode decohesion finite elements for the simulation of delamination in composite materials[R]. NASA/TM-2002-211737, 2002. [14] TURON A, CAMANHO P P, COSTA J, et al. A damage model for the simulation of delamination in advanced composites under variable-mode loading[J]. Mechanics of Materials, 2006, 38(11):1072-1089. doi: 10.1016/j.mechmat.2005.10.003 [15] HAGOORT J, WEATHERILL B D, SETTARI A. Modeling the propagation of waterflood-induced hydraulic fractures[J]. Society of Petroleum Engineers Journal, 1978, 20(4):293-303. [16] PEIRCE A, DETOURNAY E. An implicit level set method for modeling hydraulically driven fractures[J]. Computer Methods in Applied Mechanics and Engineering, 2008, 197(33–40):2858-2885. doi: 10.1016/j.cma.2008.01.013 [17] 刘保东,冯明扬,林柏欢,等. 骨料类型及界面改善对橡胶混凝土力学性能的影响[J]. 中国铁道科学,2019,40(6):9-18.LIU Baodong, FENG Mingyang, LIN Baihuan, et al. Effect of aggregate types and interface improvements on mechanical properties of crumb rubber concrete[J]. China Railway Science, 2019, 40(6):9-18. -
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