节流压井套压控制精确计算方法

发布时间：2018-11-04 15:41

【摘要】：目前工程实践中多采用间接的压力控制方法——立压控制法。采用立压控制法进行节流压井时,施加的套压合理与否,取决于对应的立压到位与否；由于压力传递存在延迟性,立压的大小需要延后一段时间才能知道,这就使得套压不能及时、准确的控制到位,增加了压力控制难度。特别是面对压力敏感性储层等复杂工况条件,由于安全窗口较窄,附加压力△P较小,对套压控制精度要求很高的情况,采用立压控制法进行节流压井存在套压控制精度低、井控安全风险大的工程难题,需要对压力控制方法进行改进,变间接的压力控制方法即立压控制法为直接的压力控制方法——套压控制法。本文根据气液两相流基本理论,结合节流压井工况下井筒环空气液两相流动的实际情况,建立描述环空压力变化规律的数学模型,通过数值计算得到满足井底压力略大于地层压力的节流压井基本原则所需套压值,进而调整节流阀开度施加相应套压,实现直接的压力控制方法——套压控制法,达到减少压力控制难度、规避井控安全风险的研究目的,对于提高复杂工况条件下的节流压井成功率具有重要的指导意义。本文的主要研究内容包括： (1)压力控制方法分析。 (2)节流压井气液两相流动数学模型。 (3)数值计算方法及工程计算软件。 (4)计算结果验证以及节流压井套压动态模拟分析。本文取得的主要研究成果有： (1)工程实践和理论分析表明,立压控制法存在压力传递滞后的特点,对于控制精度要求比较高的压井作业,需要对立压控制法进行改进。 (2)简化套压控制法与立压控制法相比,不存在压力传递延迟时间的问题,但是计算模型过于简化,精度不够,目前只能作为压井作业的参考。 (3)基于井筒环空气液两相流原理,建立了用于描述节流压井条件下环空压力分布的数学模型,结合节流压井实际情况,构建了一套便于工程应用的数学计算方法。 (4)研发了一套节流压井精确套压控制工程计算软件,可以在常规计算机上运行,避免了对计算机工作站的严重依赖,为在生产现场条件下进行精确套压控制计算提供了最重要的手段。 (5)通过与实验井实测数据的对比验证,节流压井精确套压控制工程计算软件的模拟结果,不但符合压井作业情况,误差也远小于简化套压控制的模拟结果,充分说明了研发的工程计算软件可以为实施节流压井精确套压控制提供技术支持。 (6)借助节流压井精确套压控制工程计算软件,对节流压井过程中套压变化的影响因素进行了动态模拟计算分析,得到了有益的结果,对工程实践具有重要指导意义。
[Abstract]:At present, the indirect pressure control method-vertical pressure control method is widely used in engineering practice. When the vertical pressure control method is used in the throttling well killing, the reasonable or not of the applied casing pressure depends on whether the corresponding vertical pressure is in place or not. Because of the delay of pressure transfer, the magnitude of vertical pressure needs to be delayed for a period of time, which makes the casing pressure can not be timely, accurate control in place, increasing the pressure control difficulty. Especially in the face of complicated working conditions such as pressure-sensitive reservoir, due to the narrow safety window, the small additional pressure P and the high precision requirement for casing pressure control, there is a low precision of casing pressure control by using vertical pressure control method in throttling wells. It is necessary to improve the pressure control method because of the engineering difficult problem of high safety risk in well control. The indirect pressure control method, i.e. the vertical pressure control method, is changed into the direct pressure control method, the casing pressure control method. According to the basic theory of gas-liquid two-phase flow and combined with the actual situation of air-liquid two-phase flow in wellbore annulus under the condition of throttling well killing, a mathematical model describing the variation of annular pressure is established in this paper. Through numerical calculation, the casing pressure required to satisfy the basic principle of throttling pressure which is slightly larger than formation pressure is obtained, and then the throttle valve opening is adjusted to apply the corresponding casing pressure, and the direct pressure control method-casing pressure control method is realized. To reduce the difficulty of pressure control and avoid the safety risk of well control, it is of great significance to improve the success rate of throttling well killing under complex working conditions. The main contents of this paper are as follows: (1) Analysis of pressure control method. (2) A mathematical model of gas-liquid two-phase flow in throttling well. (3) numerical calculation method and engineering calculation software. (4) validation of calculation results and simulation analysis of casing pressure in throttling well. The main research results obtained in this paper are as follows: (1) the engineering practice and theoretical analysis show that the vertical pressure control method has the characteristics of pressure transfer lag, and it requires high control precision in the well killing operation. The opposite-pressure control method needs to be improved. (2) compared with the vertical pressure control method, the simplified casing pressure control method does not have the problem of pressure transfer delay time, but the calculation model is too simplified and the precision is not enough, so it can only be used as the reference of the well killing operation. (3) based on the principle of annulus air-liquid two-phase flow in wellbore, a mathematical model is established to describe the distribution of annular pressure under the condition of throttling well killing, and a set of mathematical calculation method which is easy to be applied in engineering is constructed according to the actual condition of throttling well killing. (4) A set of engineering calculation software for precise casing pressure control of throttling well is developed, which can be run on a conventional computer and avoids the heavy dependence on computer workstation. It provides the most important means for accurate calculation of casing pressure control under the condition of production site. (5) by comparing with the measured data of experimental wells, the simulation results of precise casing pressure control engineering software for throttling wells are not only consistent with the conditions of well killing operation, but also far less than the simulation results of simplified casing pressure control. It is fully explained that the developed engineering calculation software can provide technical support for the implementation of precise casing pressure control in throttling well. (6) with the help of the precise casing pressure control engineering calculation software of throttling well, the influence factors of casing pressure change during throttling well killing are calculated and analyzed dynamically, and the beneficial results are obtained, which is of great significance to engineering practice.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE28

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