Xinjiang Oil & Gas ›› 2024, Vol. 20 ›› Issue (1): 61-67.DOI: 10.12388/j.issn.1673-2677.2024.01.008

• OIL AND GAS DEVELOPMENT • Previous Articles     Next Articles

CO2-CH4 Gas Throttling and Hydrate Generation Characteristics

  

  1. 1. Karamay Campus,China University of Petroleum (Beijing),Karamay 834000,Xinjiang,China;

    2. Research Institute of Engineering Technology,PetroChina Xinjiang Oilfield Company,Karamay 834000,Xinjiang,China

  • Online:2024-03-06 Published:2024-03-06

CO2-CH4气体节流及水合物生成特性

  

  1. 1.中国石油大学(北京)克拉玛依校区,新疆克拉玛依 834000; 2.中国石油新疆油田分公司工程技术研究院(监理公司),新疆克拉玛依 834000
  • 作者简介:熊小琴(1983-),2007年毕业于西南石油大学油气储运专业,副教授,主要从事油气输送工艺优化研究。(Tel)0990-6633310 (Email)xiongxiaoqin@cupk.edu.cn
  • 基金资助:

    1、中国石油大学(北京)克拉玛依校区科研启动基金(XQZX20230021);

    2、新疆维吾尔自治区自然科学基金资助项目“二氧化碳管道停输再启动温压协同变化机理与安全控制理论研究”(2023D01A19);

    3、新疆维吾尔自治区克拉玛依市创新环境建设计划(创新人才)项目“管输二氧化碳瞬变过程温压及相态协同变化机理和安全控制研究”(20232023hjcxrc0001);

    4、新疆维吾尔自治区“天池英才”引进计划。

Abstract:

In the process of CO2 flooding production and oil lifting,with the decrease of pressure,a large amount of associated gas will be separated from the produced liquid. In the associated gas,the content of CO2 is as high as 50%-90%. Compared with CH4,gaseous CO2 has a stronger throttling cooling effect,which may cause the generation of hydrate to block the pipeline,threatening the operation safety of the gathering and transportation system. The influence of CO2 content on the CO2-CH4 gas throttling and hydrate generation characteristics was studied using a high-pressure sapphire reactor. The results show that:When the initial pressure is high (16 MPa),the throttling effect coefficient Di of the mixture gas with the same CO2 proportion is about 1.3-5.4 ℃/MPa,and the incorporation of CH4 will enhance the throttling effect of the mixture gas,indicating that the high pressure section is mainly affected by the throttling effect of CH4;when the initial pressure is low (5 MPa,4 MPa),the throttling effect coefficient Di is about 3.4-11.9 ℃/MPa,and the incorporation of CH4 will weaken the throttling effect of the mixture gas,indicating that the low pressure section is mainly affected by the throttling effect of gaseous CO2. The higher the pressure at which CO2-CH4 gases with the same CO2 content are,the higher the temperature at which hydrates are generated,and the easier it is to generate hydrates. At the same pressure,the lower the CO2 content is,the lower the temperature at which hydrates are formed. When the CO2 content is 8%-100% and the pressure is 1.5-5 MPa,the hydrate generation temperature is 0.5~10 ℃. The comparison results between the experimental and software simulation data show that the PR equation of state has a high correlation for the calculation of CO2-CH4 throttling and hydrate generation characteristics. The research results can provide a reference for the selection of safe gathering and transportation process parameters.

Key words:

CO2-CH4 , gas, throttling characteristic, hydrate, throttling effect coefficient, CCUS

摘要:

CO2驱采油举升过程中,随着压力的降低,采出液会析出大量伴生气,伴生气中CO2含量高达50%~90%,相比CH4气体,气态CO2节流致冷效应更强,引起的低温可能会生成水合物堵塞管道,威胁集输系统的运行安全。采用高压蓝宝石反应釜研究了CO2含量对CO2-CH4气体节流及水合物生成特性的影响。结果表明:当初始压力为高压(16 MPa)时,相同CO2占比的混合气体,节流效应系数Di约为1.3~5.4 ℃/MPa,CH4的掺入将增强混合气体节流效应,说明高压段主要受CH4节流效应的影响;当初始压力为低压(5 MPa、4 MPa)时,节流效应系数Di约为3.4~11.9 ℃/MPa,CH4的掺入将减弱混合气体节流效应,说明低压段主要受气相CO2节流效应的影响;相同CO2含量的CO2-CH4气体所处压力越高,水合物生成的温度越高,越容易生成水合物;在相同压力下,CO2含量越低,生成水合物温度越低;CO2含量在8%~100%,压力在1.5~5 MPa,水合物生成温度为0.5~10 ℃。实验与软件模拟数据对比结果表明PR状态方程对CO2-CH4的节流及水合物生成特性计算具有较高的相关性。研究结果可为安全集输工艺参数的选择提供参考。

关键词:

CO2-CH4气体, 节流特性, 水合物, 节流效应系数, CCUS

CLC Number: