| 摘要: |
| 考察H2S、CO2等酸性气体在液体介质中的溶解度对同区块不同井或同井不同井段油套管腐蚀、开裂及氢脆等环境断裂情况的影响,基于模拟油气井环境下CO2溶解度的测试装置,开展CO2在不同温度、压力及矿化度下的溶解度试验,采用灰色关联度法从温度、压力及矿化度3个方面对CO2溶解度进行敏感性分析,得到CO2溶解度与温度、压力及矿化度之间的相关性,基于试验数据及改进的P-R状态方程,采用逸度系数模型与混合规则相结合的方法,拟合分析预测结果与模型中二元交互作用参数之间的相关性,得到二元交互作用参数,修正完善CO2在地层水中溶解度的预测模型,计算CO2-地层水体系在实验温度(303.15~363.15 K)、压力(5~30 MPa)及矿化度(0～0.7 mol/kg)条件下的相平衡数据。结果表明:CO2溶解度随压力变化存在转变压力(本文实验条件下的转变压力为15 MPa),在转变压力以下,CO2溶解度随压力增加更快; 温度为CO2溶解度的主控因素,压力次之,矿化度最小;CO2溶解过程受温度、压力及矿化度3种因素的混合控制,其溶解度变化趋势主要依赖于CO2气体分子在水溶液中的溶解速度和逃逸速度;优化的预测模型是准确、可靠的。 |
| 关键词: CO2溶解度 预测模型 相关性 温度 压力 矿化度 |
| DOI：10.3969/j.issn.1673-5005.2021.01.014 |
| 分类号::TQ 013 |
| 文献标识码:A |
| 基金项目: |
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| CO2 solubility test in formation water and prediction model |
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LIN Yuanhua1, DENG Kuanhai1, NING Huazhong2, SHI Yunsheng1,3, ZENG Dezhi2, LIU Wanying2
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(1.State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation in Southwest Petroleum University, Chengdu 610500, China;2.Key Laboratory of Petroleum Pipeline Engineering in Southwest Petroleum University, Chengdu 610500, China;3.School of Materials Science and Engineering in Southwest Petroleum University, Chengdu 610500, China)
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| Abstract: |
| The effects of solubility of acid gases such as H2S and CO2 in liquid medium on the corrosion and environmental fracture (SSC and HIC) of tube and casing in different wells in the same block or in different sections of the same wells were investigated. On the basis of the test device simulating the solubility of CO2 in the environment of oil and gas wells, the CO2 solubility tests under different temperatures, pressures and salinities were carried out. The gray correlation method was used to analyze the sensitivity of CO2 solubility from three aspects of temperature, pressure and salinity, through which the correlation between CO2 solubility and temperature, pressure and salinity were obtained. Based on the experimental data and the improved P-R EOS, the method of combining the fugacity coefficient model and the mixing rule was used to fit and analyze the correlation between the prediction results and the binary interaction parameters in the model, and the binary interaction parameters were obtained to modify and improve the prediction model of CO2 solubility in formation water. Phase equilibrium data of CO2 formation water system under experimental temperature (303.15-363.15 K), pressure (5-30 MPa) and salinity (0-0.7 mol/kg) were calculated. The results show that there is a transition pressure when CO2 solubility changes with pressure (the transition pressure in this experiment is 15 MPa). Under the transition pressure, CO2 solubility increases faster with pressure; the temperature is the main controlling factor of CO2 solubility, followed by pressure and salinity; the CO2 dissolution process is controlled by the mixture of temperature, pressure and salinity, and its solubility change trend mainly depends on the dissolution rate and escape speed of CO2 gas molecules in aqueous solution. The comparison between experimental data and prediction results of CO2 solubility shows that the optimized prediction model is accurate and reliable. |
| Key words: CO2 solubility prediction model correlation temperature pressure salinity |
