使用水力屏障控制单一倾斜储层中CO_2羽的迁移

Using Hydraulic Barrier Control CO_2 Plume Migration in Sloping Reservoir

在单一倾斜含水层中封存CO_2时,在浮力作用下,CO_2会向地层上升一侧快速运移,不利于封存安全.可在倾斜地层的上升一侧,距离CO_2注入井一定位置设置注水井,创造水力屏障,以阻止CO_2向上移动.建立了数值模型来探讨这一方法的有效性,分析注水位置、距离、速度等因素的影响.结果表明注水形成的水力屏障能有效阻挡CO_2羽的向上迁移,且能促进CO_2溶解,抽水能显著降低地层压力.为了确保能完全阻挡CO_2运移,需要注水长度大于CO_2羽的厚度,甚至是在全部储层注水.注水速度是影响水力屏障效果的关键因素.注水距离越近阻挡效果越好.可以在CO_2羽即将到达之前注水,以减少注水量和能源消耗.

CO_2will rapidly migrate toward the up-tilt direction of the formation under buoyancy when CO_2 is stored in the sloping aquifers.This phenomenon is not conducive to the storage security.In this paper,we are proposed setting water injection wells at a certain distance from the CO_2 injection well in the up-tilt direction of the formation.Then hydraulic barrier is created to retard upward CO_2 migration.The numerical model is set up to investigate the effectiveness of this approach,and to analyze the effects of some factors,for instance,the injection position,the injection distance and the injection rate.The results show that the hydraulic barrier caused by injecting water can effectively retard upward CO_2 migration and enhance CO_2 dissolution.Pumping water can significantly reduce the formation pressure.To ensure that CO_2 is completely retarded,the length of the injection water needs to be greater than the thickness of the CO_2 plume,even injecting water through all thickness of the formation.The rate of the injection water is the key factor affecting the effectiveness of the hydraulic barrier.The effectiveness is better when the injection water well is closer to the CO_2 injection well.The water can be injected just before the arrival of CO_2 plume to reduce the amount of injected water and energy consumption.