【作者】 杨树人；

【导师】 崔海清；

【作者基本信息】 大庆石油大学 ， 油气田开发工程， 2006， 博士

【摘要】 聚合物驱油技术可在水驱油的基础上可将原油采收率提高12%以上,在获得巨大经济效益的同时,也出现了诸如抽油杆偏磨加重,检泵周期缩短和抽油杆断杆率增加等问题。抽油杆偏磨已成为油田生产中亟待解决的问题。室内实验表明,聚驱井抽油杆在井筒偏心环空内作周期性往复运动时,由于聚合物水溶液所具有的弹性使抽油杆受到一个垂直于轴线的径向力。这个径向力使抽油杆在下行程运动过程中受压失稳提前,造成聚驱井抽油杆偏磨加重。本文选用共转Oldroyd-Maxwell流体本构方程建立起了粘弹性流体偏心环空内非定常流的流动方程;采用控制体积法对流动方程进行了离散化处理;利用交替方向隐式迭代法求解出了流场的速度分布,详细分析了环空的偏心度和抽油杆的运动参数对速度分布的影响;计算了作用在抽油杆上法向应力和作用在内管上的径向力,分析了流场几何参数、流体的弹性及抽油杆的运动对径向力的影响。结果表明:偏心度和内管运动速度对流动的影响最为明显,偏心度和流体的弹性是产生径向力根本原因,偏心度增大时流量和径向力均增大,内管运动速度增大流量和径向力的峰值也增大;径向力的存在是聚驱井抽油杆偏磨加重的主要原因;预防偏磨应从减小偏心度入手,据此提出了全井抽油杆扶正防偏磨措施,并已应用于大庆油田的6000多口聚驱井,取得了可观的经济效益。更多还原

【Abstract】 The technique of polymer-flooding can increase oil recovery by more than 12% on the basis of water-flooding, and gain enormous economic benefits, meanwhile, come forth a few problems, such as the eccentric wear of the sucker rods aggravates, the period of examining pumps and the life span of the sucker rods shortens, broken rod increases and so on. So, the eccentric wear of the sucker rods has been a problem that needs to be solved quickly. The experiment proves that the elasticity of polymer solution makes the sucker rods get a radial force perpendicular to its axes when the sucker rods of polymer flooding well does periodical in-and-fro motion in the eccentric annulus, and the radial force makes the sucker rods lose stability earlier when it was pressed down stroke, and aggravate eccentric wear of the sucker rods of polymer flooding well. Adopting common conversion Oldroyd-Maxwell constitutive equation, in this paper, the flow equation of the unsteady flow of viscoelastic fluid in the eccentric annulus was established, and was discretized with control volume method; velocity profile of the flow field was obtained by using ADI (Altering Direction Implicit) iterating method; the influence of eccentricity of annulus and motion parameter of the sucker rods on the velocity profile was discussed detailedly; the normal force acting on the sucker rods and the radial force acting on the inner rods were calculated, geometry parameter of flow field, fluid elasticity and the motion of the sucker rods that have influence on the normal force were analysed. The result shows that eccentricity and motion velocity of the inner rods have the most important influence on the flow field; eccentricity and fluid elasticity are the ultimate causes of radial force, With eccentricity increases, both flow rate and radial force also increase, when motion velocity of the inner rods increases, the peak value of flow rate and radial force increase, too; the existence of radial force is the ultimate cause of eccentric wear of the sucker rods aggravating in the polymer flooding well; preventing eccentric wear should start with reducing eccentricity. According to the above theory, measures of centralizing the sucker rods in whole bore to prevent eccentric wear have been applied to more than 6000 ploymer-flooding wells in the Daqing Oil Field, and bring about increased economic benefits.更多还原