阀门动作时水合物生成的预测与防治研究

发布时间：2018-09-04 09:00

【摘要】：在天然气管道泄压和放空过程中,由于节流效应等原因,天然气流经泄压管道时压力温度发生急剧变化,很可能导致水合物的生成。天然气水合物形成后堵塞安全阀、放空阀、泄压管线、及各种设备,导致天然气集输管线无法正常泄压,给天然气的开采、集输带来危害,甚至造成严重的安全事故。本文针对这个问题,进行了大量的文献检索和现场调研,并且进行了系统的分析研究,最终为水合物的防治提供了理论依据。本文综合油气储运和流体力学的有关理论,用模拟分析的方法,以南海乐东油田的天然气组分为例,选择了常用的三组水合物抑制剂,在经济、效率、性质等方面进行分析,优选出最佳抑制剂;同时还研究了天然气水合物平衡温度和压力的影响因素,从天然气组分、水中离子含量等方面,研究了烷烃含量、天然气含水量、酸性气体、以及水中离子的浓度、矿化度对天然气水合物生成的影响;通过南海乐东油田海上平台安全阀的实例分析,模拟计算了天然气泄压时泄压管道的压力变化情况,并且对天然气水合物的形成做出了预测,并提出了相应的解决办法;研究了天然气泄压管道,提出了通过调节管线尺寸,控制泄压管线中天然气的压力来防治水合物的办法,并且针对工程实际,对于不同的天然气集输流量,列出了最佳可选用的管道;使用有限元软件Fluent,对安全阀和节流阀在不同开度情况下的内流场进行了模拟计算,并对阀门内流场中几个压力最高或者温度最低的关键点进行水合物分析,对阀门内水合物的生成做出预测;在通过注入抑制剂控制水合物方面,本文根据泄压管线的特点,采用小型节流阀串联的方法来模拟节流阀或者泄压管道的节流效应,对于天然气在不同集输流量下的情况所需要注入的水合物抑制剂最大量做出了预测,并且拟合为通用的公式;本文同样提出了通过降压法或者升温法来防治泄压管线产生水合物,并且通过数据分析,曲线拟合,公式归纳的方法得出了天然气集输临界压力和温度的求解公式,在工程中有一定的实用性。
[Abstract]:In the process of releasing and emptying of natural gas pipeline, the pressure temperature changes sharply when the natural gas flows through the pressure relief pipeline due to throttling effect, which may lead to the formation of hydrates. After the formation of natural gas hydrate, the blockage of safety valve, emptying valve, pressure relief pipeline and all kinds of equipment lead to the failure of natural gas gathering and transportation pipeline to release the pressure normally, bring harm to natural gas mining, gathering and transportation, and even cause serious safety accident. In order to solve this problem, a large number of literature searches and field investigations have been carried out, and a systematic analysis has been carried out, which provides a theoretical basis for the prevention and cure of hydrate. In this paper, based on the theory of oil and gas storage, transportation and hydrodynamics, with the method of simulation analysis and taking the natural gas components of Ledong Oilfield in the South China Sea as an example, three groups of commonly used hydrate inhibitors are selected and analyzed in the aspects of economy, efficiency, properties and so on. At the same time, the factors affecting the equilibrium temperature and pressure of natural gas hydrate were studied, and the alkane content, natural gas water content and acid gas were studied from the aspects of natural gas composition, water ion content and so on. The influence of ion concentration and salinity on the formation of natural gas hydrate is also discussed. Through the analysis of the safety valve of offshore platform in Ledong Oilfield, South China Sea, the pressure variation of the pressure relief pipeline during the discharge of natural gas pressure is simulated and calculated. The formation of natural gas hydrate is forecasted, and the corresponding solution is put forward, the natural gas pressure relief pipeline is studied, and the method of preventing gas hydrate by adjusting the size of pipeline and controlling the pressure of natural gas in the pressure relief pipeline is put forward. According to the engineering practice, the optimal pipeline is listed for different natural gas gathering and transportation flow, and the internal flow field of safety valve and throttle valve is simulated and calculated by using finite element software Fluent, and the flow field of safety valve and throttle valve under different opening degree is simulated. At the same time, several key points in the valve flow field with the highest pressure or lowest temperature are analyzed, and the formation of hydrates in the valve is predicted. The throttle effect of throttle valve or pressure relief pipeline is simulated by using the method of small throttle valve in series. The maximum amount of hydrate inhibitor needed to be injected into natural gas under different gathering and transmission flow is predicted. This paper also puts forward the method of reducing pressure or heating temperature to prevent the gas hydrate in the pressure relief pipeline, and through the data analysis, the curve fitting, The formula induces the solution formula of the critical pressure and temperature of natural gas gathering and transportation, which has certain practicability in engineering.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TE866

【参考文献】