二氧化碳在地层水中的溶解度测定及预测模型  

CO2 solubility test in formation water and prediction model

作　　者：林元华[1] 邓宽海[1] 宁华中[2] 石云升 曾德智[2] 刘婉颖[2] LIN Yuanhua;DENG Kuanhai;NING Huazhong;SHI Yunsheng;ZENG Dezhi;LIU Wanying(State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation in Southwest Petroleum University, Chengdu 610500, China;Key Laboratory of Petroleum Pipeline Engineering in Southwest Petroleum University, Chengdu 610500, China;School of Materials Science and Engineering in Southwest Petroleum University, Chengdu 610500, China)

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室,四川成都610500 [2]西南石油大学石油管工程重点实验室,四川成都610500 [3]西南石油大学材料科学与工程学院,四川成都610500

出　　处：《中国石油大学学报（自然科学版）》2021年第1期117-126,共10页Journal of China University of Petroleum(Edition of Natural Science)

基　　金：国家自然科学基金项目(51274170,51904261,52074232)。

摘　　要：考察H_(2)S、CO_(2)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CO_(2)溶解度的测试装置,开展CO_(2)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CO_(2)溶解度进行敏感性分析,得到CO_(2)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CO_(2)在地层水中溶解度的预测模型,计算CO_(2)-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CO_(2)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,CO_(2)溶解度随压力增加更快;温度为CO_(2)溶解度的主控因素,压力次之,矿化度最小;CO_(2)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CO_(2)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。The effects of solubility of acid gases such as H2S and CO_(2) 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 CO_(2) in the environment of oil and gas wells,the CO_(2) solubility tests under different temperatures,pressures and salinities were carried out.The gray correlation method was used to analyze the sensitivity of CO_(2) solubility from three aspects of temperature,pressure and salinity,through which the correlation between CO_(2) 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 CO_(2) solubility in formation water.Phase equilibrium data of CO_(2) 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 CO_(2) solubility changes with pressure(the transition pressure in this experiment is 15 MPa).Under the transition pressure,CO_(2) solubility increases faster with pressure;the temperature is the main controlling factor of CO_(2) solubility,followed by pressure and salinity;the CO_(2) 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 CO_(2) gas molecules in aqueous solution.The comparison between experimental data and prediction results of CO_(2) solubility shows that the optimized prediction model is accurate and reliable.

关 键 词：CO_(2)溶解度 预测模型 相关性 温度 压力 矿化度 

分 类 号：TQ013[化学工程]