【作者】 王晓萍；

【导师】 王尊策；

【作者基本信息】 大庆石油学院 ， 油气田地面工程， 2010， 博士

【摘要】 气井积液造成气井水淹是制约天然气开采的重要问题,排水采气是解决此类气井开采的有效方法。应用常规排水采气工艺是将井下积液采至地面,经地面处理后,再回注地层,存在着设备多、投资大、污染环境等问题。因此,从低污染、低投入、高产出角度出发,研制一种经济有效、简单易行的,能够实现井下气液分离及回注的系统是势在必行的。气液分离设备是井下气液分离系统的主体结构,其性能的优劣直接影响系统的工作效率。结合油气田生产实际,根据气液两相流的运动规律,开展了分离装置的理论与试验研究。本文基于欧拉-欧拉理论,在考虑气液两相相互渗透、相间耦合、气液分离器内两相分离过程服从绝热的基本方程及气体的可压性的假设基础上,建立了气体可压缩的两相流模型。在此基础上,对其进行雷诺时均处理,得出可求解的气液两相的控制方程组。根据重整化群的思想,经数学推导得出有旋修正的气液两相湍流方程模型。利用所建立的气液两相流湍流模型,开展了井下分离设备的数值模拟研究,研究井下气液分离器内速度场、压力场及两相分布规律,分析了结构变化对流场、压力降及分离效率的影响关系。在此基础上,开展了井下气液分离器的结构优化设计研究,确定了适合井下气液分离的分离器结构形式。并开展了井下气液分离器性能试验研究,研究结果表明:考虑气体可压的两相流模型的模拟结果与试验结果有较好的吻合。根据气液两相绕流流动特点,开展了井下返气装置的数值模拟与试验研究,分别对返气装置内部及球浮子在单介质和气液两相绕流后,随着结构参数(球浮子直径、阻尼孔直径、底座直径)、操作参数(流量、液体体积百分含量)变化的流场分布特点及球浮子受力特征进行了理论分析,优化得到了井下返气装置结构。并与试验研究结合进行比较分析,二者的结果基本吻合,表明通过建立数学模型及数值计算方法对浮子结构及参数优选进行定性分析是可行的。在以上研究基础上,确定了井下分离系统的结构形式,提出了一种井下气液分离及产出水回注技术的新工艺,形成了以改进的空心转子螺杆泵和井下气液分离器为核心的井下分离回注系统,该系统的气液采出、为分离提供动力及回注水增压是通过一台空心转子螺杆泵来实现的,分离出的气从套管采出,井下分离出的水通过螺杆泵空心转子提供的回注通道回注,在油田两口水淹气井得到了成功应用。更多还原

【Abstract】 Gas well fluid accumulation caused by floodout is the important problem to restrict nature gas exploitation. To solve the problem by using dewatering gas production is a availability method. Application convention gas well production with water withdrawal technics was that accumulated water is lift to ground. And the gas-liquid mixture of ground handling, water injection back formation. So there are more equipment, investment, environmental pollution and other issues. From clean, low input, high output perspective, the development of a cost-effective, simple, can be achieved downhole gas-liquid separation and water injection system.Gas-liquid separation devices are important parts of downhole gas-liquid separation system, its advantages and disadvantages of a direct impact on the performance of the system’s efficiency. Combination of oil and gas production practice, according to the law of gas-liquid two-phase flow movement theory and experimental research of separation devices are carried out. Based on Euler-Euler’s theory, taken into account gas-liquid two-phase inter-penetration of alternate coupling, obeyed adiabatic equation in separation process and assumed gas compressibility that the two-phase flow model of gas compressibility is established. On this basis, the application of Reynolds-averaged treatment methods, can be obtained solving the control of gas-liquid two-phase equations. According to renormalization group ideas derived through the mathematical derivation rotating gas-liquid two-phase turbulence modified equation model.Established by the use of gas-liquid two-phase turbulence model for the downhole separation equipment to carry out numerical simulation of gas-liquid separator velocity field, pressure field and the two-phase distribution of the analysis and structural changes on the flow, pressure drop and separation efficiency of affect the relationship. On this basis, we can launch a downhole gas-liquid separator design of structural optimization to determine the suitable for downhole separation of gas-liquid separator structure. The downhole gas-liquid separator performance carried out that test result of the study show that the simulation results in considering compressibility of gas with the experimental results better match.According to characteristics of flow around with gas-liquid two-phase, numerical simulation and experimental research of exhaust were carried out with single-media and gas-liquid two-phase,.respectively. The distribution of flow field characteristics and the characteristics of the ball float force were analysised under the structural parameters (ball float diameter, damping hole diameter, base diameter), operating parameters (flow rate, liquid volume percentage content) change so that the structure of optimized exhaust. Through experiments and numerical simulation analysis and comparison, both results agree that the establishment of mathematical model and numerical calculation method is feasible.Based on the above study to determine the structural form of downhole separation system presents ,proposes downhole gas-liquid separation and produced water re-injection technology, new process, and formed a hollow rotor screw pump and an improved gas-liquid separator for downhole separation of the core hole re-injection system, gas-liquid taken out for the separation and return to power is through a water booster pumps to achieve the hollow rotor, the separated gas from the casing to adopt out, down-hole separation out of the water through the hollow rotor screw pump provided by the re-injection channel re-injection, two flooded wells in the oil field has been successfully applied.更多还原