【作者】 李治淼；

【导师】 刘巨保；

【作者基本信息】 东北石油大学 ， 油气田地面工程， 2014， 博士

【摘要】 水力压裂是油田增产增注的有效技术手段，封隔器的有效座封、水力锚的可靠锚定及压裂管柱的安全作业是水力压裂实施的保障。本文选择封隔器、水力锚以及压裂管柱为研究对象，采用理论分析、数值模拟、试验等方法，对刚体与柔性体的接触、不同硬度刚体间的嵌入、管柱与井壁的轴向摩阻与剪切等问题进行了研究，具有重要的学术价值和良好的工程应用前景。首先由拉伸压缩试验比较三种橡胶材料的拉伸强度、压缩永久变形率，优选出适于高温条件的氢化丁腈橡胶材料，测试其在不同温度下的弹性模量。以试验机作为胶筒一端压缩动力源，以压力传感器测试胶筒另一端的压力，得到胶筒压缩过程中与套管的摩阻力，以应变片测试套管外壁的环向应变，得到接触应力沿胶筒轴向分布规律。胶筒座封性能实验表明在胶筒与套管的摩阻力会影响胶筒的座封位置及发生肩突的胶筒。其次，以压缩封隔器胶筒为研究对象，考虑胶筒与套管内壁在座封过程中柔性体与刚体的间隙与不定接触边界，将胶筒压缩变形划分自由变形、单向约束、双向约束三个过程，建立了大变形胶筒与套管的弹性接触力学分析模型。采用离散法将胶筒沿轴向划分为若干微段，通过载荷增量方法来分析任一微段受力变形，推导出能够描述压缩胶筒材料、几何和接触三重非线性力学分析的递推和增量计算公式，得出胶筒在不同压力沿轴向的接触压力和整体压缩量，为封隔器设计提供科学的理论依据。采用Mooney-Rivlin模型，对不同结构的封隔器在启封、座封工况下进行受力变形分析，计算了有单保护罩、双保护罩、双保护罩且支撑环改形等结构，几种不同结构的封隔器胶筒压缩距基本相同，在完全座封状态下的肩凸程度逐渐减小；密封系数比逐渐增大。由此可以看出，有双保护罩且支撑环改形的封隔器密封性能最好，胶筒肩凸最小。再次，考虑套管的弹塑性变形及滑移线，建立了有摩擦、无摩擦两种工况下锚爪嵌入套管的弹塑性接触力学分析模型，推导了锚爪嵌入套管深度的计算公式。依据完全剪切滑脱条件，计算了单个锚爪的锚定力，为水力锚的设计提供理论基础。建立了锚爪锚定有限元模型，采用增量切线刚度法和拉格朗日乘子法，实现了材料与接触双重非线性迭代计算。通过室内压缩实验测试锚爪在不同压力下嵌入套管深度，与理论分析计算结果相符。最后，选择整体压裂管柱为研究对象，依据下井、初始座封、压裂等工作状态，建立了压裂管柱的力学模型与非线性静力学分析的有限元单元法。采用了间隙元、弹簧元来模拟计算封隔器、水力锚的轴向摩阻力与轴向锚定力，推导出多组工具的轴向摩阻力与位移协调条件，依据迭代计算结果，能够描述井下管柱的受力和变形状态。编制“压裂管柱受力变形分析软件”，计算出插入式压裂管柱的水力锚、封隔器和滑套喷砂器在压裂压力为83MPa，温度为150℃的轴向摩阻力，对一次、二次压裂作业进行了安全评价。更多还原

【Abstract】 Hydraulic fracturing is an effective technology for the increasing of production rate inthe oil field. The effective sealing of packer, the reliable anchoring of hydraulic anchor andthe safety of fracturing string’s operations are the safeguards in the hydraulic fracturing. Inthis paper, the packer, the hydraulic anchor and fracturing string are taken to be researchedby theoretical analysis, numerical simulation and the experiment. The research has greatacademic value and good prospect of engineering application, which is on the contactbetween rigid body and flexible body, the embedded depth between two rigid bodies whichhave different hardness and the friction force and shear force between fracturing string andborehole wall.Firstly, tensile strength and compression permanent deformation rate of three kinds ofrubber materials are compared by the tensile and compressive test and the optimizingmaterial hydrogenated nitrile rubber(HNBR) is suitable to work under high temperatureconditions. The elastic modulus of HNBR rubber tube is measured under differenttemperatures. The power source of rubber’s compression test come from compression testerand the compressing force under the rubber tube is measured by the pressure sensor, so thefriction force between the casing and the rubber tube is taken in compression process. Thecircumferential strain of casing wall is tested by the strain gauge to get the contact stressdistribution along axial direction of the tube. The rubber sealing test shows that the frictionforce between rubber tube and the casing affect the sealing position and which rubber tubewould protrude.Secondly, the rubber tube of compressive packer is taken as research object withconsideration of the gap between the casing and the packer and the changing contactboundary between soft rubber tube and rigid casing within sealing process. The rubber’scompressive deformation can be divided into three processes: free deforming process, singledirection constraint process and double direction constraint process. The elastic contactmechanics analysis model of rubber tube with large deformation is built. The rubber tube isdivided into some micro-sections along axial direction by discrete method. The loadincrement method is used to analysis any micro-section’s mechanical deformation of rubbertube. Recursive and incremental formula of compression rubber, which is three nonlinear mechanics about material, geometry and contact, is derived and the contact stress andcompressive length of different sections along axial direction under different pressure wouldbe obtained, which gives reliable theory basis for the packer’s design.Mechanical deformation analysis of different packer is done under the start of sealingcondition and sealing condition with Mooney-Rivlin model. The packer of differentstructure are ones with bottom protection cover, top and bottom protection cover andremodeled support ring. These models of packers have similar compressive length. Theprotruded shoulder of rubber tube become smaller and sealing factors increase. Inconclusion, the third packer has the greatest sealing property and the smallest protrudedshoulder.Thirdly, with elastic-plastic deformation and slip line of casing considered, twoelastic-plastic deformation analysis models, with and without the friction force considered,are built and plastic formulation of embedding depth is deduced to analyze embeddingdepth of hydraulic anchor’s anchor into casing. In the conditong of shearing fully andslipping, the single anchor’s anchoring force is calculated to provide fundamental basis forthe anchor’s design. Finite element model of the anchoring fluke is built. The doublenonlinear iterative calculation of material and contact is solved with the incrementaltangential stiffness method and lagrangian multiplier method. The different embeddingdepths are measured by indoor compression experiment under different pressures, which iscorresponding with the theoretical analysis results.Lastly, under different conditions of descending fracturing string, initial sealing andfracturing, mechanical model of integral fracturing string and nonlinear static finite elementmethod are built. The axial friction force and axial anchoring force is got through thesimulation method about packer and hydraulic anchor with gap element and spring element.The compatibility conditions of axial friction force and displacement is got for several setsof tools. With the iterative calculation results, the stress and deformation of the downholestring can be described. The analysis software for the stress and the deformation offracturing string is compiled. The axial friction forces for the anchor, the packer and thesliding sleeve sand jet in the plug-in fracturing string under83MPa and150℃arecalculated and a safety analysis for primary and secondary fracturing operation are done.更多还原