【作者】 黄善波；

【导师】 李兆敏；

【作者基本信息】 中国石油大学 ， 油气田开发工程， 2007， 博士

【摘要】 聚合物驱油技术作为提高注水开发油田采收率的方法,目前已得到了广泛地推广和应用。聚合物驱采油井在见聚后采出液的性质发生了变化,根据采出液中聚合物溶液含量的不同,采出液由牛顿流体变为非牛顿流体,甚至表现出弹性效应。这使聚驱井产生了许多较水驱井严重的生产问题,杆管偏磨便是其中之一。本文以此为背景,通过研究非牛顿聚驱采出液在井筒条件下的流动规律,分析聚驱井产生杆管偏磨的机理,从而为解决这一生产问题提供理论依据和支持。采用固有函数法从理论上分别对同心环空中牛顿流体、Maxwell型粘弹性流体在周期性压力梯度作用下的振荡流、内壁面沿轴向做往复运动的环空内的非定常流动进行了研究;采用SIMPLE数值方法分析了同心环空内幂律流体因入口速度脉动产生的振荡流和内壁面沿轴向做往复运动的环空内的非定常流,得到了各种流体在两种情形下环空内非定常流动的速度、平均速度、壁面处应力或摩擦系数等的变化规律,分析和讨论了环空间距、流体性质、振荡频率和振幅等因素对流动的影响。通过对极限情况的分析和讨论,验证了推导过程和数值方法的可靠性。建立了偏心环空内幂律流体、Maxwell型粘弹性流体在周期性压力梯度作用下的振荡流、内壁面沿轴向做往复运动的环空内的非定常流数学模型,分别采用有限体积法、有限差分法在双极坐标系中对其进行了数值求解,得到了偏心环空内这两种流体在两种流动条件下的速度、流量的变化规律,并分析了偏心度、流体性质、压力振荡或内壁面运动的频率和振幅对流动的影响。分析表明,有杆抽油系统在下冲程中泵端集中轴向压力和轴向分布力的综合作用使抽油杆处于受压状态而有可能失稳弯曲以及偏心环空内聚驱采出液因弹性而对抽油杆产生的侧向力是聚驱井发生杆管偏磨的两个主要原因,其中抽油杆在因弹性而产生的侧向力作用下的偏磨是聚驱井所特有的。采用Maxwell模型计算了采出液在偏心环空内流动时的侧向力。聚合物溶液的增稠特性使聚驱井的中和点上移、弯曲载荷增大、临界弯曲载荷减小;随抽油杆的增长,侧向力很容易超过杆管发生偏磨时的载荷。这些都是聚驱井偏磨现象严重于水驱井的根本原因。根据偏磨发生的机理给出了相应的解决措施。更多还原

【Abstract】 At present polymer flooding has been used widely as a means to increase the recovery factor of water flooding oilfield. The rheological characteristic of the produced fluid is changed when the polymer solution breaks through the produced wells. According to the content of the polymer solution in produced fluid, the Newtonian produced fluid may be changed to non-Newtonian fluid or viscoelastic fluid, which leads to more serious production problems compared with the water flooding wells, such as eccentric wear of the sucker rod. In order to provide theoretical supports for solving these problems, the flowing behavior of the produced fluid and the mechanism of eccentric wear of the sucker rod in polymer flooding wells would be investigated in this article.The oscillating flow in concentric annular under the periodic gradient and the unsteady flow in the concentric annular with the inner wall moving to and fro axially for the Newtonian fluid and the Maxwell viscoelastic fluid were researched theoretically by the method of eigen function. The oscillating flow due to the velocity pulsation at the annular entrance and the unsteady flow in the concentric annular with the inner wall moving to and fro axially for power-law fluid were studied numerically by the SIMPLE method. The velocity profile, average velocity, the wall stress or the frictional factor of the two flowing cases for the Newtonian fluid, the power fluid and the voscoelastic fluid were obtained. The influence of the annular space, fluid parameters, the pulsating frequency and amplitude on the flowing behavior were discussed. The derivation process and the numerical algorithm were proved to be correct by discuss of some special cases.The mathematical models of the oscillating flow in eccentric annular under the periodic gradient and the unsteady flow in eccentric annular with the inner wall moving to and fro axially for the power-law fluid and the Maxwell fluid were set up and solved numerically by the finite volume method and the finite difference method respectively in the bipolar coordinate system. The velocity profile, the flow rate of the two flowing cases for the two fluids were obtained. The effects of the annular eccentricity, fluid parameters, the pulsating frequency and the amplitude on the flowing behavior were investigated. The analysis for the sucker-rod pumping systems showed that the unstability and flexion of the sucker rod under the combined action of the axial concentrated force at the plunger pump and the axial distributed force along the rod and the lateral force along the rod due to the elasticity of the produced fluid containing polymer in eccentric annular were the reasons of the eccentric wear of the sucker rod in polymer flooding wells. The eccentric wear of the sucker rod under the action of the lateral force was special for the polymer flooding wells. The Maxwell fluid was used to calculate the lateral force in the eccentric annular. The reasons why the eccentric wears of sucker rod in polymer flooding wells were more serious than that in water flooding wells were that the bodiness trait of the polymer solution, which made the neutral point upper shift, increased the bending load and decreased the critical bending load, and the lateral forces, which can exceed the load to cause the eccentric wear of the sucker rod easily as the length of the rods increased. Appropriate measures were put forward based on the mechanisms of eccentric wear.更多还原