热力射流温度场及温度应力数值模拟研究
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摘要
热力射流破岩技术是指利用高温介质诸如超临界水对岩石进行快速局部加热达到破碎岩石的目的。由于岩石基质热导率很低,因此会在岩石表面形成温度应力。当温度应力超过岩石的强度,会在岩石内部形成微裂缝,且裂缝不断扩展最终使得岩石表面发生热裂解,热裂解作用导致岩石表面从本体脱落从而使得岩石破碎。基于热-固耦合理论建立了热裂解钻井模型,利用Crank-Nicolson差分方法求解得到了热裂解过程中井底岩石温度场和温度应力的分布规律。结果表明,在热裂解钻井过程中,岩石受热部分温度迅速升高,在径向和轴向方向上产生温度梯度;受热部分体积膨胀在径向方向上受到压应力作用,在轴向方向上发生屈曲,受到剪应力作用。研究成果对热裂解钻井的现场应用具有十分重要的指导意义。
Hydrothermal spallation drilling technology uses a high-temperature medium such as supercritical water for rapid heating of the rock locally to break the rock. The rock matrix has a very low thermal conductivity. Consequently, temperature stresses are formed on the rock surface. When the temperature stresses exceed the rock's strength, micro-cracks are formed inside the rock, and the crack will continue to expand and eventually cause thermal cracking on the rock surface, which causes the rock surface to fall off from the body, leading to breaking of the rock. Based on the thermo-solid coupling theory, a thermal cracking drilling model was established, and the distribution laws of temperature field and temperature stresses of the rock at the well bottom were obtained using the Crank–Nicolson differential method. The results show that, during the thermal cracking drilling process, the temperature of the heated part of the rock increases rapidly, and temperature gradients are generated in the radial and axial directions. The volume expansion of the heated part is subjected to compressive stress in the radial direction,and shear stress in the axial direction under buckling.
Hydrothermal spallation drilling technology uses a high-temperature medium such as supercritical water for rapid heating of the rock locally to break the rock. The rock matrix has a very low thermal conductivity. Consequently, temperature stresses are formed on the rock surface. When the temperature stresses exceed the rock's strength, micro-cracks are formed inside the rock, and the crack will continue to expand and eventually cause thermal cracking on the rock surface, which causes the rock surface to fall off from the body, leading to breaking of the rock. Based on the thermo-solid coupling theory, a thermal cracking drilling model was established, and the distribution laws of temperature field and temperature stresses of the rock at the well bottom were obtained using the Crank–Nicolson differential method. The results show that, during the thermal cracking drilling process, the temperature of the heated part of the rock increases rapidly, and temperature gradients are generated in the radial and axial directions. The volume expansion of the heated part is subjected to compressive stress in the radial direction,and shear stress in the axial direction under buckling.
引文
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[12] THIRUMALAI K, CHEUNG J B. A study on a new concept of thermal hard rock crushing[C]//The 14th US Symposium on Rock Mechanics(USRMS). American Rock Mechanics Association, 1972.
[13] AUGUSTINE C R. Hydrothermal spallation drilling and advanced energy conversion technologies for Engineered Geothermal Systems[D]. Massachusetts:Massachusetts Institute of Technology, 2009.
[14] E Silva F J R,NETTO D B,DA Silva L F F,et al. Analysis of the performance of a thermal spallation device for rock drilling[C]//Proceedings of the 11th Brazilian Congress of Thermal Sciences and Engineering-ENCIT,(Curitiba,Brazil), Brazil Society of Mechanical Sciences and Engineering-ABCM. 2006.
[15] SONG Xianzhi, LU Zehao, LI Gensheng, et al. Numerical analysis of characteristics of multi-orifice nozzle hydrothermal jet impact flow field and heat transfer[J]. Journal of Natural Gas Science&Engineering, 2016, 35:79-88. doi:10.1016/j.jngse.2016.08.013
[16] MEIER T, MAY D A, ROHR P R V. Numerical investigation of thermal spallation drilling using an uncoupled quasi-static thermoelastic finite element formulation[J].Journal of Thermal Stresses, 2016, 39(9):1138-1151. doi:10.1080/01495739.2016.1193417
[17] AMES W F. Numerical methods for partial differential equations[M]. Pittsburgh:Academic Press, 2014.
[18] LI M,NI H,WANG G, et al. Simulation of thermal stress effects in submerged continuous water jets on the optimal standoff distance during rock breaking[J]. Powder Technology, 2017, 320:445-456 doi:10.1016/j.powtec.2017.-07.071
[19] WILLIAMS R E, POTTER R M, MISKA S. Experiments in thermal spallation of various rocks[J]. Journal of Energy Resources Technology, 1996, 118(1):2-8. doi:10.1115/-1.2792690
[20] HASSANI F, NEKOOVAGHT P M, RADZISZEWSKI P, et al. Microwave assisted mechanical rock breaking[C]//12th ISRM Congress, International Society for Rock Mechanics and Rock Engineering, 2011.
[2] SMITH A G, PELLS P J N. Impact of fire on tunnels in Hawkesbury sandstone[J]. Tunnelling&Underground Space Technology Incorporating Trenchless Technology Research,2008, 23(1):65-74. doi:10.1016/j.tust.2006.-11.003
[3] SOLES J A, GELLER L B. Experimental studies relating mineralogical and petrographic features to the thermal piercing of rocks[R]. Technical bulletin(Canada. MinesBranch),Department of Mines and Technical Surveys,Mines Branch,1964.
[4] POTTER R M, TESTER J W. Continuous drilling of vertical boreholes by thermal processes:including rock spallation and fusion:U. S. Patent 5, 771, 984[P]. 1998.
[5] RAUENZAHN R M, TESTER J W. Rock failure mechanisms of flame-jet thermal spallation drilling-theory and experimental testing[J]. International Journal of Rock Mechanics and Mining Sciences&Geomechanics Abstracts,1989, 26(5):381-399. doi:10.1016/0148-9062(89)909-35-2
[6] RAUENZAHNF R M, TESTER J W. Numerical simulation and field testing of flame-jet thermal spallation drilling-2. Experimental verification[J]. International Journal of Heat and Mass Transfer, 1991, 34(3):809-818.doi:10.1016/0017-9310(91)90127-Z
[7] WILKINSON M A, TESTER J W. Experimental measurement of surface temperatures during flame-jet induced thermal spallation[J]. Rock Mechanics and Rock Engineering, 1993, 26(1):29-62. doi:10.1007/BF01019868
[8] RAUENZAHN R M. Analysis of rock mechanics and gas dynamics of flame-jet thermal spallation drilling[D]. Massachusetts:Massachusetts Institute of Technology, 1986.
[9] WALSH S D,LOMOV I,ROBERTS J J. Geomechanical modeling for thermal spallation drilling[R]. Lawrence Livermore National Lab.(LLNL),Livermore,CA(United States),2011.
[10] THIRUMALAI K, DEMOU S G. Effect of reduced pressure on thermal-expansion behavior of rocks and its significance to thermal fragmentation[J]. Journal of Applied Physics, 1970, 41(13):5147-5151. doi:10.1063/1.-1658636
[11] PRESTON F W, WHITE H E. Observations on spalling[J].Journal of the American Ceramic Society,2010, 17(1-12):137-44. doi:10.1111/j.1151-2916.1934.tb19296.x
[12] THIRUMALAI K, CHEUNG J B. A study on a new concept of thermal hard rock crushing[C]//The 14th US Symposium on Rock Mechanics(USRMS). American Rock Mechanics Association, 1972.
[13] AUGUSTINE C R. Hydrothermal spallation drilling and advanced energy conversion technologies for Engineered Geothermal Systems[D]. Massachusetts:Massachusetts Institute of Technology, 2009.
[14] E Silva F J R,NETTO D B,DA Silva L F F,et al. Analysis of the performance of a thermal spallation device for rock drilling[C]//Proceedings of the 11th Brazilian Congress of Thermal Sciences and Engineering-ENCIT,(Curitiba,Brazil), Brazil Society of Mechanical Sciences and Engineering-ABCM. 2006.
[15] SONG Xianzhi, LU Zehao, LI Gensheng, et al. Numerical analysis of characteristics of multi-orifice nozzle hydrothermal jet impact flow field and heat transfer[J]. Journal of Natural Gas Science&Engineering, 2016, 35:79-88. doi:10.1016/j.jngse.2016.08.013
[16] MEIER T, MAY D A, ROHR P R V. Numerical investigation of thermal spallation drilling using an uncoupled quasi-static thermoelastic finite element formulation[J].Journal of Thermal Stresses, 2016, 39(9):1138-1151. doi:10.1080/01495739.2016.1193417
[17] AMES W F. Numerical methods for partial differential equations[M]. Pittsburgh:Academic Press, 2014.
[18] LI M,NI H,WANG G, et al. Simulation of thermal stress effects in submerged continuous water jets on the optimal standoff distance during rock breaking[J]. Powder Technology, 2017, 320:445-456 doi:10.1016/j.powtec.2017.-07.071
[19] WILLIAMS R E, POTTER R M, MISKA S. Experiments in thermal spallation of various rocks[J]. Journal of Energy Resources Technology, 1996, 118(1):2-8. doi:10.1115/-1.2792690
[20] HASSANI F, NEKOOVAGHT P M, RADZISZEWSKI P, et al. Microwave assisted mechanical rock breaking[C]//12th ISRM Congress, International Society for Rock Mechanics and Rock Engineering, 2011.