海洋稠油热采电潜螺杆泵损伤与失效机理研究

Offshore oil field of heavy oil exploitation is influenced by factors such as environment, space and cost, and the difficulty is much higher than on land. In offshore heavy oil exploration for electric submersible progressive cavity pump, downhole high temperature environment, the large friction torque between the stator and the rotor both lead to rubber bushing's temperature rising too fast, uneven heat dissipation, degumming, swelling and jamming; The sand and other solid phase cause the stator and rotor to wear, and corrosive environment results premature failure of the pump; The complex structure and environment cause the unit comprehensive higher failure rate. These are all the the key problems need to be solved. By conducting downhole environment pressure, rotor structure, bearing form, load change and other factors, the influence of progressive cavity pump working status was studied. Under a non-newtonian medium condition, high temperature and high pressure, impact, working condition of overloading, the mathematical model of the screw pump was established. By adopting the combination of theory and experiment method to explore the real working condition of the stator and rotor,the rub-impact boundary conditions was studied.The simplified model under the condition of analytic solution and numerical solution method under different working conditions were completed. Conditions of different temperatures and different load of the screw pump were applied in the experimental study and computer simulation analysis,and the flow regularity of the internal medium under different working parameters, stator and other important parts of pressure distribution, load capacity and surface damage and failure behavior were studied deeply as well.

海上油田稠油开采受环境、空间、成本等因素的影响，其开采难度远远高于陆上。针对电潜螺杆泵开采海洋稠油时井底高温环境、定转子之间的大摩擦扭矩等导致定子橡胶衬套温升过快、散热不均，脱胶断裂、溶胀卡泵，砂粒等固相引起的定子、转子磨损，腐蚀环境下的过早失效，及结构复杂、环境恶劣导致的机组综合故障率较高等亟需解决的关键问题，通过开展井底环境压力、定转子结构、轴承形式、载荷变化等因素对螺杆泵工作状态的影响研究，建立一套非牛顿介质条件下，高温、高压、冲击、重载工况的螺杆泵定转子啮合工作状态的数学模型。采用理论与实验相结合的方法探索真实工况下定转子的滚摩边界条件，完成简化条件下模型解析求解及不同工况下的数值求解方法研究。将不同温度环境和不同载荷条件下螺杆泵的实验研究与计算机仿真分析相结合，完成螺杆泵不同工作参数下内部介质的流动规律、定转子和重要部件的压力分布、承载能力、表面损伤和失效行为的深入研究。

我国稠油资源丰富，海洋油田已探明的稠油储量占总地质储量的69%，具有良好的开发前景。然而海洋油气藏环境复杂，常规热采方式及工艺技术应用受限，电潜螺杆泵结合螺杆泵和电潜离心泵二者的优点，是目前海洋稠油开采中比较理想的井筒举升技术。然而海洋油气藏环境复杂，井下高温高压以及产液中含砂等因素会导致螺杆泵定子衬套温升过快及磨损加剧，容易引起橡胶磨损断裂、脱胶、腐蚀以及过热，导致螺杆泵过早失效。因此，有必要进行稠油开采工况下电潜螺杆泵定子衬套失效机理研究工作。. 针对上述问题，完成了稠油开采工况下电潜螺杆泵的失效机理研究工作。. （1）依据螺杆泵的内部结构和工作原理建立了双头螺杆泵的运动学模型，在此基础上设计了螺杆泵的运动学仿真模型，完成了螺杆泵的运动学仿真。. （2）基于采油螺杆泵的工作特性，设计出高温稠油环境中螺杆泵定子橡胶（丁腈橡胶）与转子的摩擦磨损试验。研究转速、砂粒浓度以及载荷对橡胶摩擦系数及磨损量的影响规律。利用电子显微镜（SEM）观察摩擦磨损试验后橡胶的表面形貌，分析了橡胶的摩擦磨损行为。. （3）设计并完成了橡胶材料在高温稠油环境下的单轴拉伸试验，分析了环境温度对橡胶材料性能的影响。. （4）以采油双头单螺杆泵为研究对象，建立螺杆泵定子衬套工作时的物理模型，基于采油螺杆泵定子橡胶滞后生热机理，建立螺杆泵定子热力耦合数学模型，研究了工作参数、结构参数、材料参数等因素对两种类型的衬套橡胶因滞后生热造成的温升影响规律。. （5）以G25-1型采油螺杆泵为试验对象，采用红外热像仪观测了采油螺杆泵定子橡胶衬套的生热过程以及热集聚效应，并研究了转速对生热过程及热集聚效应的影响规律。. 本课题采用理论、试验和数值模拟分析相结合的方法，深入研究了稠油开采工况下电潜螺杆泵的摩擦磨损失效机理和热失效机理，为电潜螺杆泵的设计、工作参数的选取以及选型提供一定的参考准则和实际依据，有助于我国海洋稠油的开发工作。