低含凝析油低渗凝析气藏凝析油污染评价及解除方法实验

传统观点认为,低含凝析油凝析气藏对储层污染很小,即使渗透率低也影响不大,因此研究较少。针对低含凝析油的低渗透凝析气藏特点,建立了近井区凝析油污染评价方法,采用0. 086 2、0. 009 19 m D两种不同渗透率的孔隙型储层岩心,分别结合凝析油含量为25. 32、52. 59 g/m3的两种低含凝析油的凝析气样品,通过测试不同衰竭压力下气相有效渗透率的变化,来评价凝析气藏近井区凝析油污染程度,并反推污染程度最大的岩心对应的凝析油饱和度,然后选择上述污染程度较大的0. 009 19 m D岩心,采用分别注入0. 1干气,以及0. 05 HCPV干气+0. 05 HCPV甲醇的方法进行凝析油污染解除对比实验,结果表明:注干气岩心渗透率恢复程度达到39. 42%,注干气+甲醇岩心渗透率恢复程度可达50. 46%。该研究为低渗透凝析气藏凝析油污染程度评价及解除提供了一种新方法。

Laboratory study on the evaluation and removal methods of condensate oil contamination in the condensate gas reservoir with low condensate oil and low permeability

In Traditional opinion, condensate gas reservoirs with low condensate oil have little contamination to the reservoir, even if the permeability is low, so there is few research in this. According to the characteristics of low permeability condensate gas reservoirs with low condensate oil, the evaluation method of condensate oil pollution near wellbore is established. The core of porous reservoirs with 0.0862 mD and 0.00919 mD permeability was used to test the different depletion pressures of condensate gas samples with condensate oil of 25.32 g/m3 and 52.59 g/m3 respectively. The change of gas effective permeability under different depletion pressure was used to evaluate the pollution degree of condensate oil near wellbore, and deduced the condensate saturation corresponding to the most polluted core. Then the 0.00919 mD core with higher pollution degree was selected to inject 0.1 HCPV dry gas and 0.05 HCPV dry gas + 0.05 HCPV methanol into the condensate gas reservoir. The recovery degree of core permeability with dry gas is 39.42%, and the recovery rate of core permeability with dry gas + methanol can reach 50.46%. This study provides a new method for evaluating and relieving condensate oil contamination in low permeability condensate gas reservoirs.