延长油田CO_2-岩石-地层水相互作用规律  

Interaction Law between CO_2,Rock and Formation Water in Yanchang Oilfield

作　　者：汤瑞佳 黄春霞 余华贵 江绍静 王维波 

机构地区：[1]陕西延长石油(集团)有限责任公司研究院,陕西西安710075

出　　处：《油田化学》2015年第4期515-519,共5页Oilfield Chemistry

基　　金：国家科技支撑计划项目"陕北煤化工CO2捕集;埋存与提高采收率技术示范"(项目编号2012BAC26B00)

摘　　要：为明确实施CO_2驱油和地质封存可能引起的物理化学变化,利用扫描电镜、X射线衍射仪、电感耦合等离子体发射光谱仪和离子色谱仪分析了延长油田储层的矿物组成,研究了CO_2-岩石-地层水之间相互作用的规律。结果表明,延长油田储层岩石主要组成为:18.7%石英、18.2%钾长石、30.1%斜长石、0.5%方解石、4.4%浊沸石和28.1%黏土矿物。地层水平均矿化度为71.34 g/L,p H值为5.5,水型为CaCl_2型。岩石-CO_2-地层水发生作用后,随着CO_2分压的增大,岩石表面的溶蚀现象愈来愈明显。在油藏温度44℃下,反应压力由0增至20 MPa时,岩石表面C元素含量呈波动上升,Na、K元素含量逐渐降低,地层水矿化度由95210增至107063 mg/L,地层水中Na^+、K^+、Ca^(2+)、HCO_3^-质量浓度呈增加趋势。反应压力由5增至20 MPa时,岩石片溶蚀率先增加后降低,压力为10 MPa时的溶蚀率最大(0.72%)。压力越大,CO_2在水中的溶解度越大,溶蚀率越高;温度和矿化度越高,CO_2溶解度越低。随着反应压力的升高,CO_2对砂岩中的钾长石和斜长石的溶蚀作用逐渐增强。To make clear the physical and chemical changes caused by CO_2 flooding and geological storage,the mineral composition of reservoir and the law of interaction between CO_2,rock and formation water in Yanchang oilfield was studied by using SEM,XRD,EDS,ICP-AES and IG. The results showed that the reservoir rock of Yanchang oilfield was composed of 18.7%quartz,18.2% potassium feldspar,30.1% plagioclase,0.5% calcite,4.4% laumontite and 28.1% clay minerals. The average salinity of formation water was 71.34 g/L with CaCl_2 type,and the p H value was 5.5. After the reaction of CO_2,rock and formation water,the corrosion of rock surface became worse with increasing partial pressure of CO_2. At reservoir temperature of 44℃,when the reaction pressure increased from 0 to 20 MPa,the content of C element in rock surface fluctuating rose,while that of Na,K elements gradually decreased,the salinity of formation water increased from 95210 mg/L to 107063 mg/L,and the mass concentration of Na~＋,K~＋,Ca^（2＋）and HCO_3^-showed an increasing trend. When the reaction pressure increased from 5 to 20 MPa,the corrosion rate of piece rock increased first and then decreased. When the pressure was 10 MPa,the maximum corrosion rate was0.72%. The higher pressure,the higher solubility of CO_2 in water and corrosion rate was. The higher temperature and salinity,the lower solubility of CO_2 in water was. With increasing reaction pressure,the dissolution of potassium feldspar and plagioclase in sandstone by CO_2 gradually increased.

关 键 词：二氧化碳 溶蚀作用 岩石 溶解度 延长油田 

分 类 号：TE341[石油与天然气工程—油气田开发工程] P584[天文地球—岩石学]