钻井过程中计算磨损套管强度的理论研究

油气井钻井过程中，由于钻具和套管相互摩擦，造成套管内壁磨损并引起磨损套管抗挤强度降低，导致某段油气井报废或整口油气井报废。因此，套管柱设计就尤为重，更重的是建立新的计算方法适应新的磨损问题。本文通过对计算方式的比较研究，得出了新的更加科学的计算磨损套管抗挤强度的算法。     

深井超深井内壁磨损套管剩余强度计算

采用理论分析和有限元相结合的方法,给出了深井超深井套管磨损面积与磨损深度预测模型,以及均布外载条件下内壁磨损套管剩余抗外挤强度和抗内压强度的计算公式。将非均布载荷等效成均布载荷,给出了非均布外载条件下内壁磨损套管剩余抗外挤强度计算公式。将建立的理论公式计算结果与现有实验数据进行了对比,二者较为吻合。建议在深井超深井套管柱强度设计与评价时考虑套管磨损和地层弹性参数的影响,同时开展不同类型磨损套管剩余强度实验研究,进一步验证理论计算结果的精度及适用条件。     

技术套管磨损程度及剩余强度分析

在大位移井、大斜度井、水平井和深井钻井中,或者在狗腿严重度较大的井段,或者在技术套管下人后的长裸眼钻井过程中,常常出现套管磨损问题。由此而诱发的套管抗挤强度和抗内压强度降低问题制约了油井的后续完井测试作业的顺利进行,影响了油井寿命,严重时还会导致某段油井报废和整口油井报废。国内外学者研究了许多措施来减缓套管磨损问题。本文在技术套管磨损程度及剩余强度分析的基础上,吸收国内外学者的减缓套管磨损问题成果,提出在技术套管磨损程度及剩余强度分析的对策。     

大尺寸储气库套管抗挤强度影响因素试验研究

根据大尺寸储气库套管受到外挤载荷时的受力及变形特点,通过室内全尺寸试验分析套管椭圆度、钢级、径厚比等因素对大尺寸储气库套管抗挤强度的影响,并利用试验数据对现有的套管抗挤计算公式进行修正。将套管变形分为弹性和塑性变形两个阶段,建立套管弹、塑性变形受力计算模型,利用能量平衡方程推导出套管抗挤强度计算公式,分析初始椭圆度、套管钢级和径厚比对大尺寸储气库套管抗挤强度的影响,将修正前后的计算结果与试验结果进行对比分析。研究结果表明:利用本文建立的套管挤毁受力模型能够很好地预测带有初始椭圆度的大尺寸储气库套管抗挤强度,计算公式简单、准确,适用于不同椭圆度、屈服强度和径厚比的套管抗挤强度计算,能够弥补现有大尺寸储气库套管规范的不足及缺失;套管的抗挤强度随着初始椭圆度和径厚比的增加而降低,随着套管钢级的增加而增加;内、外椭圆度对大尺寸储气库套管抗挤强度影响具有耦合作用,在制造过程中要严格控制椭圆度及其跳跃性,建议制订相应的储气库大尺寸套管内壁椭圆度控制规范以满足相应套管的需求。     

沥青混合料抗剪性能研究综述

总结并评价了沥青混合料抗剪试验方法、抗剪机理及抗剪设计研究现状,对9种剪切试验方法的分析和评价有助于设计、施工和科研人员正确选用这些试验方法。混合料剪切强度由沥青胶泥的性质、集料和沥青界面的剪切强度和集料之间的嵌挤情况共同决定,为提高混合料抗剪性能指出了方向。抗剪设计在应用于工程前尚需深入研究容许剪应力法中相关系数的确定、基于抗剪性能的车辙预估模型的标定等问题。     

"摩圣"(PBC)技术及其摩擦磨损特性

采用液压高精度材料试验机考察了GCr15钢平面-球面接触摩擦副在机油和摩圣机油2种介质润滑下的摩擦磨损性能.用激光扫描显微镜(LSM)观察了磨痕表面形貌并测量了磨损体积.结果表明摩圣具有较好的抗摩擦磨损性能,缩短了磨损过渡阶段的持续时间,减轻了表面粘着磨损、剥落损伤,减弱了磨粒磨损,降低了金属磨损体积损失;载荷与位移幅值增加,摩圣的抗摩擦磨损能力增强.     

HB-2五层共挤高阻隔包装复合膜研制与应用前景

介绍了HB-2五层共挤高阻隔包装复合膜的材质结构和工艺路线,并分别就阻氧性能、抗污染热封性、复合强度等问题给出了相应的解决方案.HB-2五层共挤高阻隔包装复合膜既有高阻隔性,又有透明性、抗污染性等优点,将成为高阻隔软包装领域内最具发展前景的新型包装材料.     

等离子喷涂制备钢质涂布刮刀陶瓷涂层

以涂层平面度为评价标准,通过正交试验优化等离子喷涂工艺参数,在普通蓝钢刮刀上制备Al2O3-20%TiO2涂层,并对涂层的显微形貌、结合强度和耐磨性进行了研究.结果表明:弧电流550 A,喷涂距离100 mm,走枪速度0.8 m/s时等离子喷涂制备的Al2O3-20%TiO2涂层平面度最优;涂层具有良好的结合强度和耐磨性,结合强度大于30 MPa;磨粒磨损机理为切削和脆性断裂或脱落磨损.     

等离子喷涂WC/18Co涂层微动磨损机理的研究

研究了等离子喷涂WC/18Co涂层的微动磨损机理,结果表明,涂层的微动磨损开始阶段以粘着磨损为主,涂层硬度高,抗粘着能力强,磨损轻微;稳定阶段以疲劳脱层和脆性开裂剥落为主,涂层脆性大,喷涂粒子间结合强度低,容易磨损。喷涂层内部的氧化物夹杂是造成涂层抗微动磨损能力不足的主要原因。     

钛合金干滑动摩擦行为与磨损机理研究进展

钛合金因具有高的比强度、比刚度,良好的耐蚀性和耐热性等优点,在航空航天、化工、能源等领域广泛应用,但钛合金存在表面硬度低、抗塑性剪切能力较差、不易加工硬化以及表面氧化物保护作用较差等缺陷,使其耐磨性较差,阻碍了其在耐磨损领域的发展。为了提高钛合金自身的耐磨性潜力和扩大其应用领域,本文主要概述了近年来国内外有关钛合金干滑动摩擦磨损领域的研究现状,讨论了影响钛合金摩擦磨损性能的主要因素以及在不同条件下的磨损机理,并对钛合金干滑动摩擦磨损行为的研究进行了展望。     

Investigation of the ultimate residual strengthen of a worn casing by using the arc-length algorithm

The accurate prediction of the ultimate residual strength (URS) (including collapse, burst, and tensile strength) of worn casing is important in the design and safety assessment of casings for the oil and gas industry. Based on the true stress–strain constitutive relationship of P110 steel, this paper establishes a three-dimensional (3D) finite element model (FEM) to obtain the URS of worn casing by using the arc-length algorithm. The effects of worn defect length, wear percentage, drillstring diameter, and casing thickness on the URS are investigated. Moreover, three full-scale experiments on casings with different wear percentages are conducted to verify the accuracy and reliability of the 3D FEM and of the algorithm. The validation proves that the URS of worn casing can be predicted by the 3D FEM to a satisfactory degree of accuracy. The URS has an exponential relation with defect length, but a linear relation with wear percentage, drillstring diameter, and casing thickness. The effects of numerous factors on the URS are also studied. Regression analysis is conducted on the basis of 3D FEM predictions, and the corresponding design equations for worn casing are presented.     

Experimental investigation of the failure mechanism of P110SS casing under opposed line load

Many studies focused on casing collapse strength under uniform load have been done, and the API 5C3 and ISO standards have been formed. However, only a limited number of researches on collapse failure mechanism of casing have been done under non-uniform load, especially experimental study, although the non-uniform load has a great impact on casing collapse strength. Hence, the collapse experiment is conducted for P110SS casing under opposed line load by using electro hydraulic servo pressure testing machine. The displacement variation rules of P110SS casing have been obtained under opposed line load. The strain of casing is measured in the process of collapse testing by the method of gluing strain-gauge on the outside surface of P110SS casing. The initial yield load of casing, instability load of casing and the yield load, stress-hardening rate, strain-hardening rate of casing after hardening are obtained. The stress-strain rules of casing after hardening are analyzed. The hardening characteristic and collapse failure mechanism of P110SS casing have been clarified under non-uniform load (under opposed line load). Experimental results can provide important references for the theoretical study on failure mechanism and collapse strength of casing under non-uniform load.     

Critical buckling load of paper honeycomb under out‐of‐plane pressure

Two out‐of‐plane buckling criteria for paper honeycomb are proposed by analysing the structure properties and the collapse mechanism of paper honeycomb: these are based on the peeling strength and ring crush strength of the chipboard wall. Taking into account the orthotropic, initial deflection and large deflection properties of the chipboard wall, the two new mechanical models and the calculation methods are developed to represent the out‐of‐plane critical load of paper honeycomb. Theoretical calculations and test results show that the models are suitable for describing the collapse mechanism of paper honeycomb. The peeling strength and ring crush strength determine the critical buckling load of paper honeycomb in different stretch phases. The out‐of‐plane critical buckling load can be predicted when the two models are integrated. Copyright © 2005 John Wiley & Sons, Ltd.     

某稠油井Ф88．9mm×6．45mm110EU油管挤毁原因分析

对某井在稠油开采、反注稀油过程中发生的油管挤毁和断裂事故进行了调查研究。对挤毁油管和同批新油管取样进行材质分析、尺寸测量和挤毁试验,认为油管材质和尺寸均符合标准要求。对挤毁油管外表面形状检查结果表明,油管挤毁之前没有机械损伤,油管挤毁与机械损伤无关。通过推理分析,认为油管首先发生挤毁,然后才发生断裂。通过力学分析和计算,认为油管挤毁和断裂的原因是其所受的外力超过了油管的屈服强度。     

Experimental study the collapse failure mechanism of cemented casing under non-uniform load

Under non-uniform in-situ stress, the casing collapse failure often happens easily, and especially in soft rock the problem is more serious. In addition, only the few scholars do some studies about failure mechanism of cemented casing under non-uniform in-situ stress which has a strong effect on collapse properties of cemented casing, especially testing investigation. Hence, the collapsing test was performed for cemented casing under non-uniform load (NFL) by adopting self-developed testing equipment, by which the radial deformation of cemented casing and damage rules of cement sheath have been measured and the stress-strain laws of cemented casing are obtained during the testing process by the electrical method. The initial yield load and plastic limit load of cemented casing as well as the subsequent yield load have been obtained. By analyzing testing data, the stress-hardening rate and strain-hardening rate after hardening have been determined. The effects of cement sheath on collapse properties of P110SS casing and strain and deformation laws of P110SS casing after hardening have been obtained. The hardening character and failure mechanism of cemented casing have been figured out under NFL.     

注汽井套管的三轴预应力设计

以暴露于热蒸汽中的目的层套管为研究对象,根据弹性力学理论,首先给出了套管在热应力和非均匀地应力作用下的三轴应力表达式,然后利用对套管施加预应力来降低套管的轴向热应力,以使得套管的有效应力控制在相应温度下套管的最小屈服极限内为原则,得到了热采井套管三轴预应力设计方法,并对辽河油田常用的N80钢级套管进行了预应力设计分析,给出了该套管在不同注汽温度和井深条件下所应使用的径厚比及相应的预应力值。研究表明,在实际注汽过程中适当增加注汽压力可以提高套管的安全性,传统的单轴预应力设计及只考虑热应力的三轴预应力设计结果偏于保守,建议以后注汽井在进行预应力设计时应考虑热应力和实际非均匀地应力的共同作用。     

基于套管屈曲约束的拉挤型GFRP管轴压性能

为解决复合材料空间桁架结构部分关键压杆失稳引发的连续性倒塌问题,提出了一种由不锈钢套管及螺栓连接系组成的玻璃纤维增强树脂复合材料(GFRP)管整体失稳套管屈曲约束装置。为分析该套管屈曲约束装置对拉挤型GFRP管轴压性能的影响,对3个GFRP管试件和4个套管屈曲约束GFRP管试件进行了轴压试验,观察了试件的受力过程和破坏形态,获得了荷载-位移曲线和荷载-应变曲线,对比研究了两者的极限承载力和破坏模式,同时利用有限元模型分析了不同内核长细比、内核与套管间隙及套管壁厚对GFRP管轴压性能的影响。结果表明:该套管屈曲约束装置能有效约束GFRP管整体失稳变形,其极限承载力和延性均得到提升,并使GFRP管从失稳破坏向材料强度破坏发展;内核长细比越大,套管屈曲约束GFRP管极限承载力相比于内核失稳临界荷载的相对提升幅值越高,约束效果越好;内核与套管间隙越大,GFRP管延性越好,但其极限承载力会降低;套管壁厚过薄会降低GFRP管极限承载力,过厚则约束效果不明显。      

STUDY ON CASING PERFORMANCES IN CENTRIFUGAL SLURRY PUMPS

The pump casing is the most expensive wear component of a centrifugal slurry pump. It determines to a large extent the hydraulic performance of the pump and plays a major role in the overall wear life of the unit.

This paper suggests a new approach to compute the mixture velocity and solid particle dynamics in the casing, and on this basis the erosion wear distribution inside the pump casing. Numerical analysis was performed using the finite element method. The model was tested using Georgia Iron Works (GIW) pump casings, at flowrates between 2000 and 4000 US-GPM (US gallons ner minute). The experimental results were obtained in the Hydrualic Laboratory and in field applications in mining and dredging industries. The suggested techniques are useful for estimating casing wear rates and for the optimal design and selection of slurry pumps.     

组合式车桥减速器壳盖设计优化

目的 加强组合式车桥减速器壳盖刚性和密封性,对其进行设计优化。方法 针对减速器壳盖刚性问题,在常用车桥减速器壳盖结构的基础上,对减速器壳盖周边进行翻边处理,并通过建立有限元模型对减速器壳盖刚性进行了分析计算。针对减速器壳盖渗透问题,采用了CAE分析技术对减速器壳盖进行密封性分析。为满足减速器壳盖与减速器接触平面度要求,在减速器壳盖周边接触面设计凸起压痕。结果 最终优化后减速器壳盖最大应力为155.4 MPa,小于材料屈服强度,刚性满足强度设计要求。采用CAE分析技术对减速器壳盖进行密封性分析,得出使用12个螺栓时渗漏处工作间隙为0.03 mm为最好的解决方案。结论 翻边处理后的减速器壳盖刚度高于未处理的减速器壳盖。减速器壳盖接触面设计凸起压痕,用12个螺栓拧紧减速器壳盖很好地解决了密封性和拆解问题。