【作者】 李聪；

【导师】 谢和平；

【作者基本信息】 四川大学 ， 土木工程， 2022， 博士

【摘要】 地球浅部资源已趋于枯竭,深部资源开发成为常态。向深部要能源资源已是我国当前最紧迫的现实问题,也是我国重大战略科技问题,更是我国重大的能源安全问题。向地球深部进军,需要从深地钻探、深地工程科学规律、深地资源开发利用三个层次深入开展研究,其中最关键的是深部工程科学规律研究。目前均采用“普通岩芯”获取的物理力学参数来开展研究,而深地原位环境非常复杂,深钻获取的“普通岩芯”释放了压力、温度、孔隙水等信息,已严重失真,将导致无效岩芯、资源勘探储量评估失真、深部岩层可能存在的生命体消亡和难以准确测得不同深度真实状态的岩层物理力学参数等一系列问题,导致现有深部开采技术无法考虑原位环境的真实参数,也导致深部工程实践存在一定的盲目性。其难点和技术瓶颈是如何获得保持深部赋存环境的“保真岩芯”来进行原“质”原“位”的测参数、建模型、创理论。因此,研究和发展深部岩石原位保真取芯原理与技术是关键,将为深部能源资源的开发提供必不可少的理论与技术支撑。由此,谢和平院士团队国际上首次提出深部原位“五保”(保压、保温、保质、保湿、保光)保真取芯原理与技术,获批2019-2023年度国家自然科学基金重大科研仪器研制项目“深部岩石原位保真取芯与保真测试分析系统”(项目批准号:51827901)。项目分为三大系统(深部原位保真取芯、深部原位保真移位和深部原位保真测试)、六个子系统(深部原位保压取芯、深部原位保温取芯、深部原位保质保湿保光取芯、“五保”能力率定平台、原位环境重构与移位、原位保真环境试件制备与保真测试系统)。本论文重点攻关深部原位“保压”取芯原理与技术,创新设计了多种构型保压控制器,探索了保压控制器的极限耐压强度,揭示了保压控制器的变形规律与失效机理。主要研究成果如下:(1)创新设计了多种构型保压控制器,建立了保压控制器的设计参数几何控制方程与自由运动条件下的运动状态方程,初步理清了不同构型保压控制器的几何特征与岩芯尺寸的内在联系。为提高保压控制器的极限耐压能力,设计了锥形保压控制器(A1型/A2型/A3型)、球壳形保压控制器(D型)、马鞍形保压控制器(E型)。根据牟合方盖保压控制器几何控制方程,为保证岩芯外径尺寸大于50 mm,建议锥形角度范围20°～60°。根据保压控制器运动轨迹方程,优化设计了保压控制器结构的连接方式。(2)通过保压控制器三维数值仿真,优选出了马鞍形保压控制器的最优结构构型。锥形保压控制器低压时接触压强比较平稳,当荷载增大时,保压控制器阀盖短轴中部测线处的接触压强会有较大幅度的降低,导致无法为密封圈提供足够的密封比压;球壳形保压控制器随压力增高接触压强无显著变化。依据接触压强波动幅度,得到不同构型保压控制器极限耐压强度,其中,A1型保压控制器约为27.8 MPa,A2型保压控制器约为66.3 MPa,A3型保压控制器约为100.5 MPa,D型和E型保压控制器耐压强度较高。应力分布方面,A1、A2、A3保压控制器阀盖在极限荷载条件下底面中部的等效应力较高,阀盖底面两侧的应力值比较低。随着锥形角度的增大,边缘的有效支撑面增大,极限强度也就越高。(3)建立了保压控制器力学模型,构建了保压控制器耐压强度准则,揭示了不同构型保压控制器的结构变形特征。当载荷为200 MPa时,马鞍形保压控制器最大径向位移收敛至-0.78 mm,与数值仿真结果相一致。建立了马鞍形保压控制器耐压强度与锥形保压控制器耐压强度统计模型,当α在[60°,45°]范围内变化时,马鞍形保压控制器临界荷载处于97.6 MPa～183 MPa之间。(4)基于自主研发的三代保压取芯实验室模拟测试平台(极限测试能力为200 MPa 150℃),测试了不同构型、不同材料保压控制器的极限耐压强度,并进行了优化,所研发的保压取芯控制器首次突破了100 MPa以上的极限耐压强度。深入分析了保压控制器的失效形式,归纳总结保压控制器的密封薄弱点,总结了保压控制器可能的失效模式:弯曲失效、旋转失效、屈曲失效和压溃失效。研究结果表明:优化设计的马鞍形保压控制器性能最好,大幅度提高了保压控制器的承载能力。其中,A100材料马鞍形保压控制器极限耐压强度为129.4 MPa,18Ni材料、35Cr Ni3Mo VR材料和304材料的马鞍形保压控制器(厚度8 mm)极限耐压强度均处于140 MPa以上。更多还原

【Abstract】 With the gradual depletion of the shallow resources,the exploitation of deep resources becomes normal.And exploitation of deep energy resources is an urgent energy security problem.Thus,research on the deep drilling,scientific laws and utilization of deep resources need to be further studied.The most important is the scientific laws of deep engineering.Actually,the current "ordinary core" obtained by deep drilling has released circumstances such as pressure,temperature and pore water,while the deep in-situ environment is very complex.It leads to a series of problems,such as broken cores,the inaccuracy of reserve evaluation,the extinction of possible life bodies(microorganisms,viruses,etc.)in deep rock strata,and the failure to measure the physical and mechanical parameters.Consequently,the current technology can not consider the parameters of in-situ environment,leading to a blindness in deep engineering.Therefore,it is urgent to establish deep in-situ rock mechanics and analyze mechanical behavior under deep in-situ environmental conditions.First and foremost,the key is the deep in-situ condition-preserved coring technology.In a ground-breaking first,Academician Xie’s team put forward the principle and technology of deep in-situ "Five Preservation"(pressure,temperature,quality,moisture and light preservation)coring,and the "deep rock in-situ coring and testing system" program is granted by China National Natural Science Foundation.The project consists of three systems: in-situ condition-preserved coring,in-situ condition-preserved transferring and in-situ condition-preserved testing.Additionally,the system is divided into six functional modules: in-situ pressurepreserved coring,in-situ temperature-preserved coring,in-situ quality-moisturelight preserving coring,calibration platform,in-situ environment reconstruction and in-situ testing system.This paper focuses on the principle and technology of in-situ condition-preserved coring.Several pressure controllers are innovatively designed.The ultimate bearing strength of pressure controllers with different configurations is preliminarily explored.The deformation and failure mechanisms are preliminarily revealed.The main results are as follows:(1)Based on the Steinmetz solid principle,several pressure controllers are designed.And the geometric theoretical models and motion equations are established.The geometric characteristics are preliminarily clarified.To improve the ultimate bearing capability,conical pressure controllers(A1/A2/A3),spherical shell pressure controllers(D),saddle pressure controllers(E)are designed.According to the geometric models,to ensure that the outer diameter of the core is greater than 50 mm,it is suggested that the conical angle is 20 ° ～ 60 °.At the same time,the connection is optimized according to the motion equations.(2)The numerical simulation of different pressure controllers is carried out.The stress distribution and structural deformation are preliminarily analyzed.Furthermore,the failure criterion of pressure controllers based on the contact pressure is proposed.The contact pressure of the conical pressure controller is stable at low pressure.When the load increases,the contact pressure of the weak zone will be greatly reduced,resulting in the in sufficient sealing pressure.On the contray,the contact pressure of spherical shell pressure controller is stable.Accordingly,the ultimate bearing strength of A1,A2 and A3 is 27.8 MPa,66.3 MPa and 100.5 MPa respectively.D and E has no obvious fluctuation.Under the ultimate load,the equivalent stress in the middle bottom surface of the A1,A2,and A3 covers is high,while the stress on both sides of the bottom surface is low.The effective support increases as the conical angle increases,as does the ultimate strength.(3)The mechanical model of pressure controllers is established based on the assumptions of elasticity and Kirchhoff-Love.The structural deformation of pressure controllers is revealed under various load situations.Also,the pressure controller’s strength criterion is inferred.Consequently,when the load is 200 MPa,the maximum radial displacement of the saddle-shaped pressure controller converges to-0.78 mm,which is roughly consistent with the numerical simulation.The strength criterion statistical models of conical pressure controller are established.Theoretically,The critical load of saddle shaped pressure controllers is [183 MPa,97.6 MPa] when the span is [45°,60°].(4)The laboratory test platform of pressure controllers is self-designed.It is noteworthy that the third-generation test platform has a capacity of 200 MPa and150 ℃.Moreover,the ultimate bearing strength of pressure controllers with different configurations and materials was tested.The optimized pressure coring controllers enhences the ultimate bearing strength above 100 MPa.The deformation of the valve cover is obtained.And the failure mode of pressure controllers is analyzed.The weak sealing zone of pressure controller is summarized.Besides,the possible failure modes of pressure controller are summarized.The results show that: the saddleshaped pressure controller designed has the best performance and greatly enhences the ultimate bearing capacity of the pressure controller.Evidently,the ultimate bearing strength of A100 is 129.4 MPa.The ultimate bearing strength of E made of18 Ni,35CrNi3 MoVR and 304 is above 140 MPa.更多还原