稠油油藏注蒸汽储层热伤害规律实验研究

Laboratory Study on Thermal Damage of Formation Properties During Steam Injection in Heavy Oil Reservoirs

针对稠油油藏注蒸汽过程中储层的热伤害问题,研究了稠油油藏热采过程注入的高温、高pH热流体对储层渗透率的影响,研究中利用正反向流动实验方法,研究了高温冷凝液注入疏松砂岩后引起的微粒运移作用及储层渗透率的变化特征;并利用储层矿物的水热反应实验,分析了疏松砂岩油藏注蒸汽开发过程中的微粒运移机理。实验结果表明,注蒸汽过程中,稠油油藏储层渗透率随温度及pH值的升高而降低。高速流动的蒸汽及冷凝液造成储层内固相微粒的运移及滞留,使储层非均质性进一步加剧;同时,高温、高pH的蒸汽冷凝液既促使黏土矿物发生膨胀又造成储层矿物发生溶解与转化,从而进一步加剧了稠油油藏疏松砂岩储层的储层热伤害。

For the problem of thermal damage from steam injection in heavy oil reservoir,the influence of thermal fluids（high temperature and high pH） on absolute permeability is researched in unconsolidated sandstone.Displacement experiments are employed to investigate solid-particle migration and permeability variation during hot steam condensate injection in unconsolidated sandstone.The experiments of hydrothermal reaction are conducted to analyze the migration mechanism of solid particles during steam injection in unconsolidated sandstone.The results shows that formation permeability gradually decreases as temperature and pH level increases.At high flow rate,steam and its condensate causes solid-particle migration and retention to largely decrease formation permeability.Meanwhile,under the condition of elevated temperature and high pH level,steam condensate accelerates expansion of clay minerals and causes solution and conversion of formation minerals.Therefore,formation damage is greatly increased resulting from mechanical effects and hydrothermal reactions in heavy oil reservoirs.