低渗透含水层储气库储气过程中气-水-岩相互作用及储气量影响因素

Gas-water-rock interactions and factors affecting gas storage capacity during natural gas storage in a low permeability aquifer

利用室内岩心实验研究了低渗透含水层储气库天然气储气过程中气-水-岩相互作用以及影响储气过程的主要参数。研究表明,实验条件下储气量占岩心孔隙体积的百分比为6%～20%。注气速度对储气量有重要影响,注气速度较高时,储气量较高。提高压力也会使储气量增加。统计分析表明,注气速度比压力对储气量的影响更大。储气时间对储气过程也有影响,长期储存后会有大部分天然气滞留在储集层中无法被采出。原子吸收光谱分析表明,将天然气注入盐水饱和岩心的过程中,盐水中的离子浓度和水蒸发量增大,可能形成沉淀物,降低岩石的孔隙度和渗透率。气相色谱分析表明,在岩心中储存后,天然气中二氧化碳浓度降低,甲烷浓度增加。

Gas-water-rock interactions during natural gas storage in a low permeability aquifer and main factors affecting the storage capacity were investigated in laboratory with core experiments.The results showed that gas injection flow rate had a major impact on stored gas volume and stored gas volume is higher at high flow rate.Gas storage volume ranged between 6%?20%of the pore space at experimental condition.Enhancing injection pressure can enhance gas storage volume.Statistics showed that injection flow rate had a greater influence on the gas storage volume than pressure.The retention time also had an impact on the gas storage process.Most of the natural gas was trapped in the reservoir and could not be produced after long time of retention.Atomic absorption spectroscopy indicated that ions concentrations of the brine and water evaporation increased when gas was injected into brine saturated core,and precipitation might occur,reducing porosity and permeability of core.Gas chromatography analysis showed that the concentration of carbon dioxide in the natural gas decreased and the concentration of methane increased after storage in the core.