Effects of acid fracturing fluid on dynamic fracture behavior and energy dissipation characteristics of anthracite coal
GONG Shuang1，2，ZHANG Hansong1，ZHAO Yixin3，SUN Shiyi1，ZHOU Yongheng1，SHEN Wenlong1
(1. School of Energy Science and Engineering，Henan Polytechnic University，Jiaozuo，Henan 454003，China；2. State Collaborative Innovation Center of Coal Work Safety and Clean-efficiency Utilization，Jiaozuo，Henan 454003，China；
3. School of Energy and Mining Engineering，China University of Mining and Technology(Beijing)，
Beijing 100083，China)
Abstract：To investigate the effect of acidic fracturing fluid on the fracture behavior and energy dissipation of anthracite under impact load，a split Hopkinson pressure bar(SHPB) impact loading system was used to conduct model-I dynamic fracture toughness tests on notched semi-circular bending(NSCB) anthracite samples treated with acidic fracturing fluid and water-based fracturing fluid under varying impact pressures. The dynamic crack propagation process of coal samples was recorded by high-speed camera device. Combined with Image J analysis software and PCAS image recognition system，the macroscopic crack propagation trajectory and probability entropy of micro pores in coal samples were quantitatively analyzed. By comparing the incident energy，absorbed energy，fracture energy and residual kinetic energy of anthracite samples under different impact pressures and various fracturing fluids，the energy dissipation law of dynamic fracture process of acid corroded coal samples under impact loads was obtained. The results show that the dynamic fracture toughness of coal samples in natural state is the largest，and the fracture toughness of coal samples treated with acid fracturing fluid is lower than that of water-based fracturing fluid when the impact pressure is higher than 0.35 MPa. The prefabricated cracks in acidic fracturing fluid-treated coal samples are more likely to initiate under higher loading air pressure conditions. The difference between the fracture energy required by acid fracturing fluid group and that of water-based fracturing fluid group increases with the increase of loading pressure. The higher the loading air pressure，the less fracture energy required for the acid fracturing fluid treated coal samples compared to the water-based fracturing fluid group. The pore probability entropy value of coal sample fracture surface increases with the increase of impact pressure，and the fracture surface morphology of coal sample transforms from compact and neat to loose and porous due to the action of acid fracturing fluid. The dual mechanism of weakening and enhancing the fracture behavior of anthracite coal by fracturing fluid under different loading rates was explored，and a microscopic fracture mechanics model considering the loading rate was established based on the dual nature of fracturing fluid and the theory of linear elastic fracture mechanics. The research results provide experimental support for the investigation of crack initiation and propagation mechanism of acid fracturing for anthracite coal，and provide theoretical guidance for the design of acid fracturing in coal seam and the control method of complex fracture network.
[1] 袁 亮. 我国深部煤与瓦斯共采战略思考[J]. 煤炭学报，2016，41(1)：1–6.(YUAN Liang. Strategic thinking of simultaneous exploitation of coal and gas in deep mining[J]. Journal of the China Coal Society，2016，41(1)：1–6.(in Chinese))
[2] 秦 勇，袁 亮，胡千庭，等. 我国煤层气勘探与开发技术现状及发展方向[J]. 煤炭科学技术，2012，40(10)：1–6.(QIN Yong，YUAN Liang，HU Qianting，et al. Status and development orientation of coal bed methane exploration and development technology in China[J]. Coal Science and Technology，2012，40(10)：1–6.(in Chinese))
[3] 姚艳斌，刘大锰，黄文辉，等. 两淮煤田煤储层孔–裂隙系统与煤层气产出性能研究[J]. 煤炭学报，2006，31(2)：163–168.(YAO Yanbin，LIU Dameng，HUANG Wenhui，et al. Research on the pore-fractures system properties of coalbed methane reservoirs and recovery in Huainan and Huaibei coal-fields[J]. Journal of the China Coal Society，2006，31(2)：163–168.(in Chinese))
[4] ZHENG Y F，ZHAI C，CHEN A K，et al. Microstructure evolution of bituminite and anthracite modified by different fracturing fluids[J]. Energy，2023，263：125732.
[5] LAU H C，LI H Y，HUANG S. Challenges and opportunities of coalbed methane development in China[J]. Energy and Fuels，2017，31(5)： 4 588–4 602.
[6] 孙粉锦，王 勃，李梦溪，等. 沁水盆地南部煤层气富集高产主控地质因素[J]. 石油学报，2014，35(6)：1 070–1 079.(SUN Fenjin，WANG Bo，LI Mengxi，et al. Major geological factors controlling the enrichment and high yield of coalbed methane in the southern qinshui basin[J]. Acta Petrolei Sinica，2014，35(6)：1 070–1 079.(in Chinese))
[7] 邹才能，杨 智，黄士鹏，等. 煤系天然气的资源类型、形成分布与发展前景[J]. 石油勘探与开发，2019，46(3)：433–442.(ZOU Caineng，YANG Zhi，HUANG Shipeng，et al. Resource types，formation，distribution and prospects of coal-measure gas[J]. Petroleum Exploration and Development，2019，46(3)：433–442.(in Chinese))
[8] 李国庆，孟召平，王保玉. 高煤阶煤层气扩散–渗流机制及初期排采强度数值模拟[J]. 煤炭学报，2014，39(9)：1 919–1 926.(LI Guoqing，MENG Zhaoping，WANG Baoyu. Diffusion and seepage mechanisms of high rank coal-bed methane reservoir and its numerical simulation at early drainage rate[J]. Journal of the China Coal Society，2014，39(9)：1 919–1 926.(in Chinese))
[9] 朱庆忠，鲁秀芹，杨延辉，等. 郑庄区块高阶煤层气低效产能区耦合盘活技术[J]. 煤炭学报，2019，44(8)：2 547–2 555.(ZHU Qingzhong，LU Xiuqin，YANG Yanhui，et al. Coupled activation technology for low-efficiency productivity zones of high-rank coalbed methane in Zhengzhuang block，Shanxi，China[J]. Journal of the China Coal Society，2019，44(8)：2 547–2 555.(in Chinese))
[10] 葛兆龙，卢义玉，周 哲，等. 煤层控制水力压裂裂缝导向扩展理论与技术[M]. 北京：科学出版社，2020：5–23.(GE Zhaolong，LU Yiyu，ZHOU Zhe，et al. Theory and technology of controlling hydraulic fracturing fracture-oriented propagation in coal seam[M]. Beijing：Science Press，2020：5–23.(in Chinese))
[11] 管保山，刘玉婷，刘 萍，等. 煤层气压裂液研究现状与发展[J]. 煤炭科学技术，2016，44(5)：11–17.(GUAN Baoshan，LIU Yuting，LIU Ping，et al. Present situation and development of coalbed methane fracturing fluid[J]. Coal Science and Technology，2016，44(5)：11–17.(in Chinese))
[12] 苏现波，汤友谊，盛建海. 河南省煤层气开发工艺初探[J]. 焦作工学院学报，1998，17(6)：406–408.(SU Xianbo，TANG Youyi，SHENG Jianhai. On three proposals of the coalbed methane development in Henan province[J]. Journal of Jiaozuo Institute of Technology，1998，17(6)：406–408.(in Chinese))
[13] 胡千庭，李晓旭，陈 强，等. 酸性压裂液防治低渗煤层水锁损害实验研究[J]. 煤炭学报，2022，47(12)：4 466–4 481.(HU Qianting，LI Xiaoxu，CHEN Qiang，et al. Mitigating water blockage in low-permeability coal seam by acid-based fracturing fluid[J]. Journal of the China Coal Society，2022，47(12)：4 466–4 481.(in Chinese))
[14] 高建良，方迎香，刘佳佳，等. 多组分酸酸化对中马村矿高阶煤增透效果的影响[J]. 安全与环境学报，2022，22(6)：3 119–3 126. (GAO Jianliang，FANG Yingxiang，LIU Jiajia，et al. Influence of multi-component acid acidification on anti-reflection effect of high-rank coal in Zhongmacun Mine[J] Journal of Safety and Environment，2022，22(6)：3 119–3 126.(in Chinese))
[15] 范 耀. 前置酸压裂提高煤层气单井产量机制与适用性研究[J]. 煤田地质与勘探，2021，49(4)：153–161.(FAN Yao. Mechanism and applicability of increasing coalbed methane well production by pre-positioned acid fracturing[J]. Coal Geology and Exploration，2021，49(4)：153–161.(in Chinese))
[16] HE J W，LI H，YANG W，et al. Experimental study on erosion mechanism and pore structure evolution of bituminous and anthracite coal under matrix acidification and its significance to coalbed methane recovery[J]. Energy，2023，283：128485.
[17] ZHANG B X，DENG Z，FU X H，et al. An experimental study on the effects of acidization on coal permeability：Implications for the enhancement of coalbed methane production[J]. Energy，2023，280：128145.
[18] 龚 爽，赵毅鑫，王 震，等. 层理对煤岩动态裂纹扩展分形特征的影响[J]. 煤炭学报，2021，46(8)：2 574–2 582.(GONG Shuang，ZHAO Yixin，WANG Zhen，et al. Effect of bedding on the fractal characteristics of dynamic crack propagation in coal rocks[J]. Journal of the China Coal Society，2021，46(8)：2 574–2 582.(in Chinese))
[19] 方士正，杨仁树，李炜煜，等. 基于NSCB方法的冻结红砂岩动态断裂特性试验[J]. 工程科学学报，2023，45(10)：1 704–1 715. (FANG Shizheng，YANG Renshu，LI Weiyu，et al. Investigation of dynamic fracture characteristics of frozen red sandstone using notched semi-circular bend method[J]. Chinese Journal of Engineering，2023，45(10)：1 704–1 715.(in Chinese))
[20] RAZAVI N，ALIHA M R M，BERTO F. Application of an average strain energy density criterion to obtain the mixed mode fracture load of granite rock tested with the cracked asymmetric four-point bend specimens[J]. Theoretical and Applied Fracture Mechanics，2018，97：419–425.
[21] YIN T B，BAI L，LI X，et al. Effect of thermal treatment on the mode Ⅰ fracture toughness of granite under dynamic and static coupling load[J]. Engineering Fracture Mechanics，2018，199：143–158.
[22] WEI M D，DAI F，LIU Y，et al. A fracture model for assessing tensile mode crack growth resistance of rocks[J]. Journal of Rock Mechanics and Geotechnical Engineering，2023，15(2)：395–411.
[23] XIONG J，LIU K Y，SHI C，et al. Logging prediction and evaluation of fracture toughness for the shales in the Longmaxi formation，Southern Sichuan Basin[J]. Petroleum，2021，7(3)：254–262.
[24] YANG H W，KRAUSE M，RENNER J. Determination of fracture toughness of mode Ⅰ fractures from three-point bending tests at elevated confining pressures[J]. Rock Mechanics and Rock Engineering，2021，54(10)：5 295–5 317.
[25] PENG K，LV H，ZOU Q L，et al. Evolutionary characteristics of mode-Ⅰ fracture toughness and fracture energy in granite from different burial depths under high-temperature effect[J]. Engineering Fracture Mechanics，2020，239：107306.
[26] LI C，HU Y Q，MENG T，et al. Mode-Ⅰ fracture toughness and mechanisms of salt-rock gypsum interlayers under real-time high-temperature conditions[J]. Engineering Fracture Mechanics，2020，240：107357.
[27] ZHANG Q B，ZHAO J. Effect of loading rate on fracture toughness and failure micromechanisms in marble[J]. Engineering Fracture Mechanics，2013，102：288–309.
[28] LV Y C. Effect of bedding plane direction on fracture toughness of shale under different loading rates[J]. Chinese Journal of Rock Mechanics and Engineering，2018，37(6)：1 359–1 370.
[29] 李光雷，蔚立元，靖洪文，等. 酸腐蚀后灰岩动态压缩力学性质的试验研究[J]. 岩土力学，2017，38(11)：3 247–3 254.(LI Guanglei，YU Liyuan，JING Hongwen，et al. Experimental study of dynamic compressive mechanical properties of limestone after acid corrosion[J]. Rock and Soil Mechanics，2017，38(11)：3 247–3 254.(in Chinese))
[30] 廖 健，赵延林，刘 强，等. 酸化学腐蚀下灰岩剪切强度特性试验研究[J]. 采矿与安全工程学报，2020，37(3)：639–646.(LIAO Jian，ZHAO Yanlin，LIU Qiang，et al. Experimental study on shear strength characteristics of limestone under acidizing corrosion[J]. Journal of Mining and Safety Engineering，2020，37(3)：639–646.(in Chinese))
[31] 张重远，窦子豪，周伦仕，等. 酸蚀作用对岩石裂隙剪切行为的影响规律研究[J]. 岩石力学与工程学报，2023，42(增1)：3 256– 3 265.(ZHANG Chongyuan，DOU Zihao，ZHOU Lunshi，et al. Effect of acid corrosion on shear behaviors of rock fractures[J]. Chinese Journal of Rock Mechanics and Engineering，2023，42(Supp.1)： 3 256–3 265.(in Chinese))
[32] 谢 妮，王丁浩，吕 阳，等. 酸腐蚀作用下川渝红层砂岩蠕变特性试验研究[J]. 地质科技通报，2022，41(5)：141–149.(XIE Ni，WANG Dinghao，LV Yang，et al. Experimental study on creep behaviors of red sandstone in Sichuan and Chongqing under acid corrosion[J]. Bulletin of Geological Science and Technology，2022，41(5)：141–149.(in Chinese))
[33] 陈立超，王生维，张典坤. 酸化反应对煤矿顶板硬砂岩断裂行为的影响[J]. 地下空间与工程学报，2023，19(4)：1 188–1 195.(CHEN Lichao，WANG Shengwei，ZHANG Diankun. Influence of acidizing reaction on fracture behavior of hard sandstone of coal mine roof[J]. Chinese Journal of Underground Space and Engineering，2023，19(4)：1 188–1 195.(in Chinese))
[34] 何春明，郭建春. 酸液对灰岩力学性质影响的机制研究[J]. 岩石力学与工程学报，2013，32(增2)：3 016–3 021.(HE Chunming，GUO Jianchun. Mechanism study of acid on mechanical properties of limestone[J]. Chinese Journal of Rock Mechanics and Engineering，2013，32(Supp.2)：3 016–3 021.(in Chinese))
[35] WANG Z P，GE Z L，LI R H，et al. Effects of acid-based fracturing fluids with variable hydrochloric acid contents on the microstructure of bituminous coal：An experimental study[J]. Energy，2022，244：122621.
[36] GUO Y，LI X，HUANG L. Insight into spontaneous water-based working fluid imbibition on the dynamic tensile behavior of anisotropic shale[J]. Engineering Geology，2022，308：106830.
[37] XIAO Y J，HURICH C，BUTT S D. Assessment of rock-bit interaction and drilling performance using elastic waves propagated by the drilling system[J]. International Journal of Rock Mechanics and Mining Sciences，2018，105：11–21.
[38] SHENG M，TIAN S C，CHENG Z，et al. Insights into the influence of fluid imbibition on dynamic mechanics of tight shale[J]. Journal of Petroleum Science and Engineering，2019，173：1 031–1 036.
[39] CARROLL M M. Mechanics of geological materials[J]. Applied Mechanics Reviews，1985，38(10)：1 256–1 260.
[40] REVNIVTSEV V. I. We really need revolution in comminution[C]// International Mineral Processing Congress. [S. l.]：Elsevier Science Publishers Amsterdam，1988：93–114.
[41] PRASHER C L. Crushing and grinding process handbook[M]. Chichester：John Wiley and Sons Limited，1987：1–5.
[42] CHI G，FUERSTENAU M C，BRADT R C，et al. Improved comminution efficiency through controlled blasting during mining[J]. International Journal of Mineral Processing，1996，47(1/2)：93–101.
[43] 宫凤强，王 进，李夕兵. 岩石压缩特性的率效应与动态增强因子统一模型[J]. 岩石力学与工程学报，2018，37(7)：1 586–1 595. (GONG Fengqiang，WANG Jin，LI Xibing. The rate effect of compression characteristics and a unified model of dynamic increasing factor for rock materials[J]. Chinese Journal of Rock Mechanics and Engineering，2018，37(7)：1 586–1 595.(in Chinese))
[44] 刘晓辉，戴 峰，刘建锋，等. 考虑层理方向煤岩的静动巴西劈裂试验研究[J]. 岩石力学与工程学报，2015，34(10)：2 098–2 105. (LIU Xiaohui，DAI Feng，LIU Jianfeng，et al. Brazilian splitting tests on coal rock considering bedding direction under static and dynamic loading rate[J]. Chinese Journal of Rock Mechanics and Engineering，2015，34(10)：2 098–2 105.(in Chinese))
[45] ZHANG Q B，ZHAO J. A review of dynamic experimental techniques and mechanical behaviour of rock materials[J]. Rock Mechanics and Rock Engineering，2014，47(4)：1 411–1 478.
[46] ZHANG Z X，KOU S Q，JIANG L G，et al. Effects of loading rate on rock fracture：Fracture characteristics and energy partitioning[J]. International Journal of Rock Mechanics and Mining Sciences，2000，37(5)：745–762.
[47] 陈 荣，郭 弦，卢芳云，等. Stanstead花岗岩动态断裂性能[J]. 岩石力学与工程学报，2010，29(2)：375–380.(CHEN Rong，GUO Xuan，LU Fangyun，et al. Research on dynamic fracture behaviors of Stanstead granite[J]. Chinese Journal of Rock Mechanics and Engineering，2010，29(2)：375–380.(in Chinese))
[48] 谢和平. 分形–岩石力学导论[M]. 北京：科学出版社，2005：62–78.(XIE Heping. Introduction to fractal-rock mechanics[M]. Beijing：Science Press，2005：62–78.(in Chinese))
[49] 王 浩，宗 琦，汪海波，等. 冲击荷载下饱水凝灰岩断裂韧性及裂纹扩展分形特征研究[J]. 岩石力学与工程学报，2023，42(7)： 1 709–1 719.(WANG Hao，ZONG Qi，WANG Haibo，et al. Fractal characteristics of fracture toughness and crack propagation of saturated tuff under impact loads[J]. Chinese Journal of Rock Mechanics and Engineering，2023，42(7)：1 709–1 719.(in Chinese))
[50] 李夕兵. 岩石动力学基础与应用[M]. 北京：科学出版社，2014：58–62.(LI Xibing. The basis and application of rock dynamics[M]. Beijing：Science Press，2014：58–62.(in Chinese))
[51] 刘 春，许 强，施 斌，等. 岩石颗粒与孔隙系统数字图像识别方法及应用[J]. 岩土工程学报，2018，40(5)：925–931.(LIU Chun，XU Qiang，SHI Bin，et al. Digital image recognition method of rock particle and pore system and its application[J]. Chinese Journal of Geotechnical Engineering，2018，40(5)：925–931.(in Chinese))
[52] 施 斌. 黏性土击实过程中微观结构的定量评价[J]. 岩土工程学报，1996，18(4)：60–65.(SHI Bin. Quantitative assessment of changes of microstructure for clayey soil in the process of compaction[J]. Chinese Journal of Geotechnical Engineering，1996，18(4)：60–65.(in Chinese))
[53] ZHOU Z L，CAI X，MA D，et al. Water saturation effects on dynamic fracture behavior of sandstone[J]. International Journal of Rock Mechanics and Mining Sciences，2019，114：46–61.
[54] GUO Y，LI X，HUANG L，et al. Effect of water-based working fluid imbibition on static and dynamic compressive properties of anisotropic shale[J]. Journal of Natural Gas Science and Engineering，2021，95：104194.
[55] VAN EECKHOUT E M. The mechanisms of strength reduction due to moisture in coal mine shales[J]. International Journal of Rock Mechanics and Mining Sciences and Geomechanics Abstracts，1976，13(2)：61–67.
[56] ROSSI P. A physical phenomenon which can explain the mechanical behaviour of concrete under high strain rates[J]. Materials and Structures，1991，24：422–424.
[57] 龚 爽，赵毅鑫. 层理对煤岩动态断裂及能量耗散规律影响的试验研究[J]. 岩石力学与工程学报，2017，36(增2)：3 723–3 731. (GONG Shuang，ZHAO Yixin. Effects of bedding on fracture characteristics and energy dissipation of coal under impact loading[J]. Chinese Journal of Rock Mechanics and Engineering，2017，36(Supp.2)：3 723–3 731.(in Chinese))
[58] 陈军斌，张 杰. 页岩气储层液体火药高能气体压裂增产关键技术研究[M]. 北京：科学出版社，2017：10–32.(CHEN Junbin，ZHANG Jie. Research on key technologies for increasing production of shale gas reservoir by liquid gunpowder high energy gas fracturing[M]. Beijing：Science Press，2017：10–32.(in Chinese))
[59] MCCONNELL B J. Factors controlling sandstone strength and deformability in uniaxial compression[Ph. D. Thesis][D]. Bristol：University of Bristol，1989.
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