超深层孔隙型热储地热尾水回灌堵塞机理

Reinjection clogging mechanism of used geothermal water in a super-deep-porous reservoir

超深层孔隙型地下热水回灌难的问题已成为制约关中盆地地下热水可持续开发利用的瓶颈。本文以超深层孔隙型地热流体为载体,以热储原水-回灌尾水-热储介质-堵塞垢物之间水岩作用下矿物组分溶解沉淀规律为基础,以咸阳回灌1号井为例,应用室内堵塞实验模拟及水文地球化学模拟耦合方法,展开超深层孔隙型地热尾水回灌堵塞机理研究。结果表明:造成堵塞的主要因素有物理、化学、气体、微生物等,其中物理堵塞形式主要为颗粒运移和悬浮物堵塞,颗粒运移受回灌流速和储层物性影响明显,温度、压力是悬浮物堵塞的主控因素,而粘土膨胀影响甚微;化学堵塞程度随温度升高而加剧,主要化学沉淀为碳酸盐垢,且在回灌初期-中期达到沉淀量最大值;气体堵塞在回灌初期影响较大,之后随温度升高而减小;微生物堵塞的主要细菌类型为腐生菌,其堵塞程度与环境开放程度有关。

Reinjection to the super-deep-porous reservoir is hard to realize.It has become the key problem restricting the sustainable development and utilization of geothermal water in the Guanzhong basin.In this paper,based on the study of the solution and precipitation tendency of different minerals during water-rock interaction process between used water and water-medium in a geothermal reservoir,the clogging mechanism of reinjection is studied with the indoor clogging experiment and the hydro geochemical simulation coupling method.The results show that the main factors causing clogging during reinjection mainly are physic-clogging,chemical-clogging,gas-clogging and microorganism-clogging.The physical-clogging is caused by particle migration,suspended matter clogging and clay expansion.Reinjection-velocity and physical-property obviously influence the particle migration,and temperature and pressure are the main controlling factors.Clay expansion has a little effect on pyhsical-clogging.The chemical-clogging aggravates with higher temperature.Its precipitate is mainly carbonate and it achieves the maximum in the initial and interim of the reinjection process.Gasclogging happens in the beginning of reinjection process and decreases as the temperature increases.Saprophytic bacteria are the main type of microorganism clogging affected by the opening of environment.