石油学报 ›› 2022, Vol. 43 ›› Issue (8): 1173-1184.DOI: 10.7623/syxb202208011

• 石油工程 • 上一篇    下一篇

海域天然气水合物降压开采压力控制及气液流动特性

刘争1, 孙宝江1, 王志远1, 陈龙桥2, 王鄂川2, 陈立涛1, 王金堂1   

  1. 1. 中国石油大学(华东)石油工程学院 山东青岛 266580;
    2. 中国石油集团海洋工程有限公司 天津 300280
  • 收稿日期:2021-07-11 修回日期:2022-05-10 出版日期:2022-08-25 发布日期:2022-09-05
  • 通讯作者: 孙宝江,男,1963年11月生,1999年获北京大学博士学位,现为中国石油大学(华东)教授,主要从事海洋油气工程、井控多相流理论及应用研究工作。Email:sunbj1128@vip.126.com
  • 作者简介:刘争,男,1992年11月生,2018获中国石油大学(华东)硕士学位,现为中国石油大学(华东)博士研究生,主要从事井筒多相流、水合物开发及流动保障等方面的研究工作。Email:liuz1113@126.com
  • 基金资助:
    国家自然科学基金重大项目(No.51991363,No.51991365)和中国石油天然气集团有限公司科技重大项目(ZD2019-184-003)资助。

Pressure control and gas-liquid flow characteristics of offshore natural gas hydrate extraction by depressurization

Liu Zheng1, Sun Baojiang1, Wang Zhiyuan1, Chen Longqiao2, Wang Echuan2, Chen Litao1, Wang Jintang1   

  1. 1. School of Petroleum Engineering, China University of Petroleum, Shandong Qingdao 266580, China;
    2. CNPC Offshore Engineering Co., Ltd., Tianjin 300280, China
  • Received:2021-07-11 Revised:2022-05-10 Online:2022-08-25 Published:2022-09-05

摘要: 针对海域天然气水合物降压开采井身结构和管柱设计的特点,综合考虑水合物储层-生产井动态耦合、井下加热器预热和电潜泵实时排采的影响,建立了水合物降压生产期间井筒气液两相流模型及数值求解算法,提出了基于瞬态多相流实时优化泵排量的生产压差自动控制方法,并利用日本第1次水合物试采和中国南海深水气井现场实测数据对模型进行了验证。结合海域水合物试采的地质条件和环境特征,开展数值模拟研究,检测了不同生产压差控制方法的性能,分析了不同生产设计参数条件下生产管柱内的气液流动特性。研究结果显示,所提出的方法能够准确完成降压目标,而Shimizu方法具有一定的随机性;在水合物降压开采过程中,增大生产管柱的管径、施加井口回压、降低电潜泵的安装深度和提高生产压差均可以降低井内的液位高度,其中井口回压对液位高度的影响起着绝对主导作用,而电潜泵位置的影响最小;当采气管线的管径减小至0.108 m、井口回压低于0.12 MPa、生产压差小于2.16 MPa时,主流管线内会出现连续排水现象。

关键词: 天然气水合物, 电潜泵, 气液两相流, 生产压差, 液位, 参数设计

Abstract: Based on the characteristics of the well structure and pipe column design for the natural gas hydrate extraction by depressurization in the sea area,comprehensively considering the influences from the dynamic coupling of hydrate reservoir and production well,downhole heater preheating and electric submersible pump (ESP) real-time drainage,this paper establishes a gas-liquid two-phase flow model and numerical solution algorithm for the wellbore during the production of hydrates by depressurization,and proposes an automatic control method for the production pressure difference based on the transient multi-phase flow to optimize the pump discharge in real time.The model was validated using the first hydrate pilot production in Japan and the field measurement data of a gas well in deep water of the South China Sea.Further,according to the geological conditions and environmental characteristics of hydrate pilot production in the sea area,numerical simulations were performed to test the performance of the production pressure difference control methods proposed in this paper and other literatures,and the gas-liquid flow characteristics in the production pipe column under different production design parameters were analyzed.The results show that the proposed method can accurately accomplish the depressurization targets,while the method of Shimizu Corporation has a certain randomness;in the process of hydrate extraction by depressurization,the liquid level height in the well can be reduced by increasing pipe diameter of the production pipeline column,applying the wellhead back pressure,reducing installation depth of the ESP,and increasing the production differential pressure.Specifically,the wellhead back pressure plays an absolutely dominant role in influencing the liquid level height,and the ESP location has the least effect;when the pipe diameter of the gas extraction line is reduced to 0.108 m,the wellhead back pressure is lower than 0.12 MPa,and the production differential pressure is less than 2.16 MPa,the continuous drainage phenomenon will occur in the main flow line.

Key words: natural gas hydrate, electric submersible pump, gas-liquid two-phase flow, production differential pressure, liquid level, parameter design

中图分类号: