数值模拟在CO_2地质封存示范项目中的应用

Application of numerical simulation to pilot project of CO_2 geological sequestration

CO2深部咸水层地质封存被认为是减缓温室效应的一种有效的工程技术手段。针对神华鄂尔多斯105t/a CO2捕集与封存(CCS)示范项目,用数值模拟方法对CO2在地层中的运移过程进行了详细地刻画,分析了CO2的流动迁移、地层压力积聚过程及地层封存潜力。数值模型不但可以为工程的顺利进行提供技术支撑,而且可以节省人力财力。首先,根据实际监测数据对模拟参数进行校准,得到了合适的压力拟合曲线,确定了主要的水文地质参数。然后,对为期3 a的CO2续注工程进行预测,详细分析了CO2的晕扩散、溶解情况、地层压力变化情况、储层封存潜力等。得到如下结论:CO2在3 a内的最大迁移距离约为350 m;水裂可以有效提高CO2的注入性;隔离层能有效防止CO2逃逸。研究表明,尽管鄂尔多斯盆地属于低渗咸水层仍然能够有效安全地封存CO2。

The geological sequestration of CO2in deep saline aquifer is an effective countermeasure for reducing global warming and greenhouse effect.Based on the Shenhua Ordos CO2 capture and storage（CCS） pilot project,the behavior of CO2 in deep saline aquifers is investigated.The transport process of CO2 fluid,the pressure buildup of system and the reserves potential of sequestration are analyzed.This model can provide technological support and save human and financial resources for Shenhua CCS engineering project.First,the model is calibrated by comparing simulated results and measured pressure values.The suitable pressure curve is obtained and the main hydrological parameters are determined at this stage.Then an assumption of CO2 continuing injection for 3 years is simulated based on the former model.The CO2diffusion,solution behavior,pressure variation and total reserves of strata are analyzed.The conclusions are drawn as follows： the largest distance of CO2 migration is about 350 m;hydraulic fracturing can improve CO2 injectivity obviously;cap rock can effectively prevent the escape of CO2.Simulation results demonstrate that even though the deep saline aquifers of Ordos basin has low penetrability,it is also suitable for CO2sequestration.