气井自由套管力学行为与井口抬升相关性研究

发布时间：2018-04-22 06:11

本文选题：轴向复合刚度 + 高温高压　；参考：《西南石油大学》2017年硕士论文

【摘要】：高温高压气井大都具有埋藏深、产量高、含酸性气体、地质条件复杂的特点。随着高温高压气井的逐渐投产,这部分气井由于自由套管所引起的井口抬升、井口管线损坏、完井管柱安全问题逐渐突显,已经成为影响此类气井安全生产的重要问题之一。为准确预测高温高压气井井口装置抬升高度并评估其安全性,指导气井安全生产,迫切需要开展自由套管力学特性的研究。提出了水泥环套管胶结面机械咬合强度、胶结强度的测试方法,开展了具有不同胶结面积的水泥环套管剪切实验,得到了轴向载荷与水泥环套管轴向变形之间的关系,计算了水泥环套管胶结面机械咬合强度、胶结强度及其占比,弄清了完井后自由套管的形成机理。基于能量守恒、动量守恒定律,建立了高温高压高产气井井筒温度场、压力场计算模型,提出了一种温压耦合求解方法;并以温度场、压力场计算模型为基础,建立了油套管柱轴向复合刚度系统轴向应力的计算模型,该模型考虑了环空流体膨胀、套管热效应、管柱屈曲、井眼轨迹以及封隔器对轴向应力的影响,结合井口装置抬升机理,形成了预测高温高压高产气井井口装置抬升高度的方法。基于轴向复合刚度力学模型和井筒温压场计算模型,引入粒子群多目标优化算法,建立了以井口抬升测量信息为基础反演高温高压高产气井各层自由套管长度的理论模型,结合井口装置抬升机理,形成了计算各层自由套管长度的新方法,并利用四川盆地Y气井井口装置抬升高度的计算实例验证了该新方法的准确性及可靠性。基于轴向复合刚度力学模型和井筒温压场计算模型编制了气井自由套管力学行为与井口抬升相关性计算程序,模拟计算了四川盆地X气井的温度场、压力场,与X气井井口温度及环空压力实测数据吻合,并分析了产量、环空保护液返深、环空流体及水泥环物性参数对环空压力的影响规律;模拟计算了 X气井寿命周期内各产量条件下的井口装置抬升高度,分析了产量及各层自由套管长度对井口抬升高度的影响规律;模拟计算了不同自由套管长度组合的套管柱轴向应力,分析了自由套管组合与轴向应力、安全系数之间的相关性:模拟计算了不同产量下的套管柱轴向应力,分析了产量与轴向应力、安全系数之间的相关性。计算结果表明:井口抬升高度随着产量和自由套管长度增加而增加,X气井井口抬升高度对生产自由套管长度的变化最敏感,技术套管次之,表层套管最小;套管轴向应力与自由套管长度和产量密切相关,即某一层自由套管长度相对过长或相对过短都会显著降低套管的安全性,产量的增加也会明显降低套管的安全性。
[Abstract]:High temperature and high pressure gas wells are characterized by deep burial, high production, acid gas and complicated geological conditions. With the gradual production of high temperature and high pressure gas wells, the wellhead uplift caused by free casing in this part of gas wells, the damage of wellhead pipelines and the safety problems of completion string have become one of the important problems affecting the safe production of this kind of gas wells. In order to accurately predict the lift height of high temperature and high pressure gas wells, evaluate its safety and guide the safe production of gas wells, it is urgent to study the mechanical properties of free casing. This paper puts forward the testing method of mechanical bite strength and cementing strength of cement annular casing surface. The shear experiments of cement sheath casing with different cementing area are carried out, and the relationship between axial load and axial deformation of cement sheath casing is obtained. The mechanical bite strength, cementing strength and ratio of cement casing cementing surface are calculated, and the formation mechanism of free casing after completion is clarified. Based on the conservation of energy and momentum, the calculation model of temperature field and pressure field in high temperature and high pressure gas well is established, and a method for solving the coupling of temperature and pressure is put forward, which is based on the calculation model of temperature field and pressure field. The axial stress calculation model of the axial composite stiffness system of oil casing string is established. The model takes into account the influence of annular fluid expansion, casing heat effect, string buckling, wellbore trajectory and Packer on axial stress. Based on the lifting mechanism of the wellhead device, a method for predicting the height of the wellhead device in high temperature and high pressure gas wells is developed. Based on axial composite stiffness mechanics model and wellbore temperature and pressure field calculation model, a theoretical model for inversion of free casing length in high temperature and high pressure gas wells based on wellhead lift measurement information is established by introducing particle swarm multi-objective optimization algorithm. A new method for calculating the length of free casing in each layer is formed based on the uplift mechanism of wellhead device. The accuracy and reliability of the new method are verified by an example of calculating the uplift height of wellhead installation in Y gas well in Sichuan Basin. Based on axial composite stiffness mechanics model and wellbore temperature and pressure field calculation model, a program for calculating the correlation between the mechanical behavior of free casing and wellhead uplift in gas wells is developed, and the temperature and pressure fields of X gas wells in Sichuan Basin are simulated and calculated. It agrees with the measured data of wellhead temperature and annular pressure in X gas well, and analyzes the effect of production rate, circumferential protection fluid depth, annular fluid and physical parameters of cement ring on annular pressure. The uplift height of the wellhead device under various production conditions during the life cycle of X gas well is simulated and the influence of production rate and free casing length on the wellhead uplift height is analyzed. The axial stress of casing string with different free casing length combinations is simulated and calculated, and the correlation between free casing combination and axial stress and safety factor is analyzed. The axial stress of casing string under different production rate is simulated and calculated. The correlation between yield, axial stress and safety factor is analyzed. The results show that the increase of wellhead lift height with the increase of production rate and free casing length is the most sensitive to the change of production free casing length, followed by technical casing, and the lowest is surface casing. The axial stress of casing is closely related to the length and output of free casing. That is to say, the safety of casing will be significantly reduced if the length of a certain layer of free casing is relatively long or too short, and the safety of casing will be obviously reduced with the increase of output.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE931.2

【相似文献】