油气藏评价与开发 ›› 2023, Vol. 13 ›› Issue (3): 280-287.doi: 10.13809/j.cnki.cn32-1825/te.2023.03.002

• 方法理论 • 上一篇    下一篇

枯竭气藏CO2封存中的相平衡规律研究

杨宇1(),徐启林1,刘荣和2,黄东杰3,颜平1,王建猛1   

  1. 1.成都理工大学能源学院,四川 成都 610059
    2.中国石油川庆钻探工程有限公司,四川 成都 610051
    3.四川省非金属(盐业)地质调查研究所,四川 自贡 643021
  • 收稿日期:2022-12-02 出版日期:2023-06-26 发布日期:2023-06-26
  • 作者简介:杨宇(1973—),男,博士,教授,主要从事油气藏精细描述、数值模拟工作。地址:四川省成都市成华区二仙桥东三路1号,邮政编码:610059。E-mail:yangyu@cdut.edu.cn
  • 基金资助:
    国家科技重大专项“丝绸之路经济带大型碳酸盐岩油气藏开发关键技术”(2017ZX05030)

Phase equilibrium law of CO2 storage in depleted gas reservoirs

YANG Yu1(),XU Qilin1,LIU Ronghe2,HUANG Dongjie3,YAN Ping1,WANG Jianmeng1   

  1. 1. College of Energy, Chengdu University of Technology, Chengdu, Sichuan 610059, China
    2. CNPC Chuanqing Drilling Engineering Co., Ltd., Chengdu, Sichuan 610051, China
    3. Sichuan Institute of Nonmetallic (Salt Industry) Geological Survey, Zigong, Sichuan 643021, China
  • Received:2022-12-02 Online:2023-06-26 Published:2023-06-26

摘要:

在枯竭气藏CO2注入及封存过程中,注入的CO2引起气、水、固三相之间的再平衡,伴随出现CO2溶解、水蒸发和盐析现象,影响近井带地层物性。以川西的枯竭气藏为例,采用SRK-HV方程和盐析模型分析了枯竭气藏CO2注入过程中的三相变化规律。研究表明:在定容体系中的CO2注入过程中,随着CO2物质的量增加,气相压力增大,CO2溶解度逐渐增大,H2O在气相中的摩尔分数逐渐降低,但H2O在气相中的物质的量不断增加,说明水的总蒸发量加大。此外,水蒸发引起的水相体积减小量相对于初始水相体积较小。因此,地层水矿化度增加幅度较小。CO2的溶解加快了CaCO3的析出,同时抑制了CaSO4、CaSO4·2H2O的析出。在氯化钙型地层水中,随着矿化度增加,地层水中会析出CaCO3和CaSO4两种盐成分。该研究成果对枯竭气藏CO2注入过程中水蒸发及盐析规律研究具有一定的借鉴意义。

关键词: 枯竭气藏, CO2封存, 相平衡, 地层水蒸发, 盐析

Abstract:

In the process of CO2 injection and storage of a single well in depleted gas reservoirs, the injected CO2 causes the rebalance among gas, water and solid, and the accompanying CO2 dissolution, water evaporation and salting out affect the physical properties of the formation near this well. Therefore, taking depleted gas reservoir in western Sichuan as an example, the SRK-HV equation and salting out model are used to analyze the three-phase change rule during the CO2 injection process of the depleted gas reservoir. The researches show that during the CO2 injection process in the constant volume system, with the increase of the number of mole of CO2, the gas phase pressure increases, the CO2 solubility gradually increases, and the mole fraction of H2O in the gas phase gradually decreases, but the total number of mole of H2O in the gas phase continuously increases, indicating that the total evaporation of water increases. In addition, the water phase volume reduction caused by water evaporation is smaller than the initial water phase volume, so the increase of formation water salinity is small. The dissolution of CO2 accelerates the precipitation of CaCO3, while inhibiting the precipitation of CaSO4 and CaSO4·2H2O. In calcium chloride type formation water, CaCO3 and CaSO4 will be separated with the increase of salinity. The research results has certain reference significance for the study of water evaporation and salting out during CO2 injection in depleted gas reservoirs.

Key words: depleted gas reservoir, CO2 storage, phase equilibrium, formation water evaporation, salting out

中图分类号: 

  • TE135