延长油田CO2驱过程中无机盐沉积规律  

Inorganic salt precipitation law in process of CO_2 flooding in Yanchang Oilfield

作　　者：肖娜 李实[2] 林梅钦[3] 

机构地区：[1]长江大学石油工程学院油气钻采工程湖北省重点实验室,湖北武汉430100 [2]中国石油勘探开发研究院,北京100083 [3]中国石油大学(北京)提高采收率研究院,北京102249

出　　处：《断块油气田》2018年第1期85-88,92,共5页Fault-Block Oil & Gas Field

基　　金：中国石油科技创新基金项目“低渗透裂缝性油藏CO2驱提高采收率技术的基础研究”(2015D-5006-0206)

摘　　要：CO_2驱替过程中,CO_2注入油藏后,极易与地层流体、岩石发生反应。而当地层压力、温度、地层水中离子质量浓度等改变时,溶液中无机盐可能沉淀析出,导致储层物性发生改变。储层物性的变化将直接影响到采收率的提高和CO_2地质封存的效果和规模。文中通过分析CO_2与CaCl_2溶液及地层水之间的相互作用发现,酸性条件下CO_2不会与CaCl_2溶液及地层水反应产生沉淀;通过模拟采出井附近降压过程发现,降压过程会导致沉积物析出,其中快速降压较缓慢降压过程沉积物析出更明显,高压条件下较低压条件下降压过程中沉积物析出更明显。In the process of CO_2 flooding, CO_2 can react with formation fluid and rock when it is injected into the reservoir. With the change of pressure, temperature or ion concentration, inorganic salt can subside from the formation fluid. This results in the variations of reservoir properties and thus affect the efficiency of CO_2 flooding and sequestration. The interactions between CO_2 and Ca Cl2 solution, CO_2 and formation water were studied in this paper. The study shows that precipitation does not occur under acidic conditions. By simulating depressurization process near the production well, it is found that precipitation occurs in depressurization process. It appears more obvious in rapid depressurization process than in slow depressurization process and more obvious in high pressure than in low pressure.

关 键 词：CO2驱 油藏 PH值 相互作用 沉积 降压过程 

分 类 号：TE357.45[石油与天然气工程—油气田开发工程]