井下多级节流降低高温高压气井环空带压风险的研究

发布时间：2018-07-15 18:28

【摘要】：随着天然气井勘探开发的不断深入,井筒完整性问题受到越来越多的关注,尤其在高温高压气井生产过程中,持续环空带压的问题越来越突出,对安全生产造成了严重的威胁,这引起了油田专家和学者的广泛关注。较高的环空温度是导致环空带压的一个关键因素,而且它会加剧含硫气田中油套管的腐蚀,甚至可能引起人员伤亡和环境危害。因此,有必要采取一定措施来降低井筒环空温度,从而能够有效降低环空压力,提高井筒完整性和延长气井的生产寿命。本文提出了一种控制环空带压的新方法,即在高温高压气井中,将井下节流器安装在一个较合适的井底位置,从而有效控制由环空温度升高导致的井口持续环空带压现象。对于高温高压气井,安装一个井下节流器并不能够将井口温度和压力降低至理想值,可能需要采用井下多级节流技术。本文对井下节流流动特性进行了分析,并对井下节流和井口节流的优缺点进行了对比分析。基于传热学以及流体力学相关理论,应用动量守恒、能量守恒定律和井下节流温降压降模型,建立高温高压气井采用井下多级节流技术后井筒温度和压力分布计算模型,并进行了敏感性分析。根据传热学理论,建立了环空温度和压力预测计算模型。基于节流温降压降计算模型和热膨胀导致的环空带压机理,利用气井节点系统分析方法,根据拟实现的井口温度、压力和允许的环空带压值来确定井下节流器的个数。在此基础上,对国内某气井应用井下多级节流技术来降低环空带压进行了实例计算。
[Abstract]:With the development of exploration and development of natural gas wells, more and more attention has been paid to wellbore integrity, especially in the production process of high temperature and high pressure gas wells, the problem of continuous annular zone pressure is becoming more and more prominent, which poses a serious threat to the safety of production. This has aroused the extensive concern of oil field experts and scholars. Higher annulus temperature is a key factor leading to annular zone pressure, and it will aggravate the corrosion of oil casing in sulfur-bearing gas field, and may even cause casualties and environmental hazards. Therefore, it is necessary to take some measures to reduce the wellbore annulus temperature, so as to effectively reduce the annulus pressure, improve wellbore integrity and prolong the production life of gas wells. In this paper, a new method of controlling annular zone pressure is proposed, that is, in high temperature and high pressure gas wells, the downhole throttle is installed in a more suitable bottom hole position, thus effectively controlling the phenomenon of continuous annular zone pressure in the wellhead caused by the increase of annulus temperature. For high temperature and high pressure gas wells, the installation of a downhole throttle can not reduce the wellhead temperature and pressure to an ideal value, so it may be necessary to adopt downhole multistage throttling technology. In this paper, the characteristics of downhole throttling flow are analyzed, and the advantages and disadvantages of downhole throttling and wellhead throttling are compared. Based on the relevant theories of heat transfer and fluid mechanics, applying momentum conservation, energy conservation law and downhole throttling temperature and pressure drop model, a well bore temperature and pressure distribution model after adopting downhole multistage throttling technology in high temperature and high pressure gas wells is established. Sensitivity analysis was carried out. Based on the theory of heat transfer, the prediction model of temperature and pressure in annulus is established. Based on the calculation model of throttling temperature and pressure drop and the mechanism of annular zone pressure caused by thermal expansion, the number of downhole throttle is determined according to the expected wellhead temperature, pressure and allowable annulus zone pressure by using the method of gas well nodal system analysis. On this basis, the application of downhole multistage throttling technology to reduce annular zone pressure in a gas well in China is calculated.
【学位授予单位】：西南石油大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TE28

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