致密砂岩气藏反凝析伤害及开采对策研究

针对中江气田沙溪庙组气藏反凝析伤害导致气井产量下降的问题,基于沙溪庙组气藏流体相态变化特征研究,通过长岩芯反凝析伤害实验及数值模拟分析评价反凝析对气藏开发的影响。结果表明,气藏在开发过程中,反凝析将导致储层中气相渗透率大幅降低,储层渗透率伤害率达32%,最大含凝析油饱和度1.8%,压裂改造工艺在一定程度上能降低气藏反凝析伤害,且储层渗透率越高,气藏反凝析对气井产能影响越小。根据中江沙溪庙组气藏生产特征分析,采用衰竭式开发方式更为适合,建议开采初期通过气井合理配产,延长气井露点压力以上生产时间,后期可介入泡排、柱塞气举等工艺排出井筒积液,确保气井稳定,最终达到提高气藏开发效益的目的。

Research on the Retrograde Condensate Damage and Development Strategies in Tight Sandstone Gas Reservoir

Retrograde condensation damage of gas reservoirs decreases the productivity of the gas well during the development of Shaximiao Formation in Zhongjiang Gas Field. According to the characteristics of fluid phase change in gas reservoir, the influence of retrograde condensate on gas reservoir development is evaluated by retrograde condensate damage experiments for the long core and numerical simulation analysis. The results show that during the development of the gas reservoir, the retrograde condensate damage will greatly reduce the gas phase permeability. The core permeability damage rate is 32%, and the maximum condensate saturation is 1.8%. The fracturing can effectively reduce the degree of the retrograde condensation damage, the higher the reservoir permeability is, the smaller the effect of reverse condensation on gas well productivity is. Based on the analysis of the production characteristics of Shaximiao Formation in Zhongjiang gas field, it is suggested to prolong the producing time above the dew point pressure by reasonable production allocation of gas wells in the early stage of production, means of foam drainage and plunger gas lift in the later stage can be used to discharge the accumulated oil in the wellbore, to ensure the stability of gas wells and ultimately improve the development benefit of gas reservoirs.