北塘凹陷新近系馆陶组的CO_2-EATER实验研究  

CO_2-EATER Model on Guantao Formation of Beitang Sag

作　　者：李义曼[1,2] 庞忠和[1] 杨峰田[1,3] 

机构地区：[1]中国科学院地质与地球物理研究所工程地质力学重点实验室,北京100029 [2]中国科学院大学,北京100049 [3]吉林大学环境与资源学院,长春130021

出　　处：《科技导报》2013年第27期15-20,共6页Science & Technology Review

基　　金：<科技导报>博士生创新研究计划资助项目(kjdb2011004);国家高技术研究发展计划(863计划)"十二五"项目(2011AA050604)

摘　　要：地热尾水回灌率低是目前中国沉积盆地砂岩储层中-低温地热资源可持续开发利用的瓶颈。基于利用CO2提高地热回灌率,即CO2-EATER(CO2-Enhanced Aquifer Thermal Energy Recovery)概念模式,以黄骅坳陷中部北塘凹陷新近系馆陶组砂岩热储层为例,利用高温高压反应釜实验模拟了反应时间为10d,温度为100℃,压力为10MPa人工注入CO2条件下,水-岩-CO2相互作用及其对储层水化学组分及矿物组分的改变和对孔隙度及渗透率可能的影响。结果表明,CO2注入后,储层水的pH值从7.7下降到6.3,储层水的HCO3-、Ca、Mg、Na和K等组分显著增加。这是由于CO2溶解于水,形成了酸性环境,储层中长石类矿物和方解石发生溶解而释放出金属阳离子。地层水的δ18O H2O和δ2H H2O分别发生了3.5‰和3‰的负漂移,表明人工CO2的注入促进了水-岩反应。X衍射(XRD)和扫描电镜(SEM)分析结果也证实了长石类矿物的溶解,这对改善储层具有一定意义,也说明CO2-EATER模式可能适合于北塘凹陷新近系馆陶组。Low reinjectivity of geothermal waste water has become the bottle-neek for sustainable use of low-medium temperature geothermal resources widely found in sedimentary basins of China. Based on conceptual model of CO2-EATER （CO2-Enhaneed Aquifer Thermal Energy Recovery）. Tertiary sandstone reservoir of Guantao formation in Beitang sag of the Middle of Huanghua Depression is taken as a testing example. Water-roek-CO2reaetion at a temperature of 100℃ and a pressure of 10MPa is carried out for 10d using high temperature ＆ high pressure Parr, to understand the corresponding effects on eomponent changes Of formation water and minerals as well as formation porosity and permeability. Results show that after CO2 injection, pH dropped from original 7.7 to 6.3 and components like HCO3-, Ca, Na and K showed signifieant rise. The reason is that dissolved CO2 forming aeidic eonditions and cations like K, Ca and Na were released into formation water due to dissolution of feldspar and carbonate minerals, which are also eonfirmed by X-Ray Diffraction （XRD） and Scanning Electron Microscopy （SEM） results. Water isotopes results also indicate that artificial C02 addition into formation water accelerates water-rock interaction and leads to ＂Reversed oxygen-shifs＂of δ8OH2O and δ2H2O by 3.5‰ and 3‰,respectively.It can be coneluded that CO2 injection can stimulate the geothermal reservoirs and CO2-EATER model is feasible for Tertiary Guantao formation of Beitang sag.

关 键 词：北塘凹陷 馆陶组 地热水回灌 CO2-EATER 水-岩-CO2相互作用 

分 类 号：P618.13[天文地球—矿床学]