高压高产气井油管气液两相流特性研究

发布时间：2018-09-06 14:26

【摘要】：天然气作为清洁能源越来越受到世界各个国家的重视,气液两相流在石油天然气工业中起着重要的作用。在高压高产气井试气求产过程中,由于井下复杂的动载荷容易造成地层入侵到环空中形成段塞流,其流动特性对油管工作性能有很重要的影响。在反循环洗井中,井底存在固、液、气多相流易堵塞油管,近而使得油管内压力急剧变化,最终导致油管被挤毁失效。在回顾了气液两相流国内外研究现状和对元坝区块进行环境调研并对案例中油管进行了宏观特征分析、理化性能分析、微观金相分析后,本文对油管内气液两相流中气柱压力发生急剧下降原因进行了分析,并以油管为研究对象,采用理论与数值模型相结合的方法,对油管内段塞流的形成、气柱在油管内的运动规律以及气液两相流的压力变化特性进行了模拟和计算。利用三轴强度计算法计算出油管的抗挤毁强度。最后,为了避免油管发生被挤毁失效,提出了相应的改善措施。本文得出结论有:油管除了抗拉强度低于规定标准外,其他性能都满足要求,油管被挤毁的力学条件与井下的动载荷(如油管内外压差较大)有关;油管内气液两相流中气柱压力急剧下降和油管被堵塞后环空的水锤效应造成了油管内外压差增大,最终导致油管被挤毁;油管内气柱压力变化与气柱长度、油管下端堵塞程度、气柱初始速度以及油管堵塞深度等因素有关;油管所承受外载荷已经超过了油管的抗挤毁强度。
[Abstract]:Natural gas, as a clean energy, has been paid more and more attention by many countries all over the world, and gas-liquid two-phase flow plays an important role in oil and gas industry. In the process of gas test and production in high pressure and high production gas wells, the complicated dynamic load in downhole can easily cause formation invasion to form slug flow in the annulus, and its flow characteristics have a very important influence on the performance of tubing. In reverse circulation washing wells, there are solid, liquid and gas multiphase flow at the bottom of the well, which is easy to block the tubing, which causes the pressure in the tubing to change sharply and finally causes the tubing to be destroyed and destroyed. After reviewing the present research situation of gas-liquid two-phase flow at home and abroad, the environmental investigation of Yuanba block and the analysis of the macroscopic characteristics, physical and chemical properties and microscopic metallography of the tubing in the case, In this paper, the causes of the sharp drop of gas column pressure in gas-liquid two-phase flow in tubing are analyzed. Taking the tubing as the research object, the formation of slug flow in the tubing is studied by combining the theory with the numerical model. The movement law of gas column in tubing and the pressure variation characteristics of gas-liquid two-phase flow are simulated and calculated. The compressive strength of the tubing is calculated by using the triaxial strength calculation method. Finally, in order to avoid the tubing collapsing failure, the corresponding improvement measures are put forward. The conclusions are as follows: except the tensile strength of tubing is lower than the prescribed standard, all other properties meet the requirements, and the mechanical condition of tubing being crushed is related to the dynamic load (such as large pressure difference between inside and outside of tubing); In the gas-liquid two-phase flow in the tubing, the pressure of the gas cylinder drops sharply and the water hammer effect of the annulus after the tubing is blocked causes the pressure difference inside and outside the tubing to increase and eventually lead to the tubing being crushed, the pressure variation and the length of the gas column in the tubing, the plugging degree of the lower end of the tubing, The initial velocity of the gas column and the depth of the tubing blockage are related to the external load of the tubing which has exceeded the compressive strength of the tubing.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE832

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