【摘要】 温室气体CO₂在枯竭气藏中埋存和提高气藏采收率是目前世界研究热点。为了揭示气藏中CO₂埋存与提高气藏采收率之间的关系和影响因素,开展了高温高压条件下CO₂驱替CH₄的长岩心实验。通过8 MPa、80℃下长岩,心驱替实验研究了驱替速度、地层倾角、储层渗透率和束缚水存在对CH₄采收率、CO₂突破时间及埋存的影响。实验结果表明:CO₂驱替CH₄过程采收率在86.92%⁹8.63%,CO₂突破时间在0.702 PV⁰.879 PV,CO₂突破时CH₄采收率在71.73%⁸7.56%。有束缚水存在时储层中CO₂饱和度约为55%,溶解在水中部分占1.9%PV。驱替速度越小,CO₂突破越快,最终CH₄采收率越小;高注低采45°比低注高采10°、45°时CO₂突破要分别早0.1 PV、0.17 PV,采收率低约3.3%;束缚水存在使CO₂突破滞后0.11 PV,最终CH₄采收率增加约3%;渗透率越低时,相同注入PV时CO₂突破时间越早,最终CH₄采收率越低。研究结果说明,气藏中注CO₂可提高气藏采收率及实施CO₂埋存,CO₂超临界性质、重力作用、低速下扩散以及CO₂在地层水中溶解不容忽视。更多还原

【Abstract】 CO₂ sequestration with enhanced gas recovery in depleted gas reservoirs gains its worldwide attention and popularity at present.In this study,high temperature and high pressure experiments performed on CO₂ flooding in long core samples,aiming to provide a relationship between CO₂ sequestration and enhanced gas recovery.Effects of displacing velocity,formation dip,reservoir permeability and connate water on methane recovery,CO₂ breakthrough time and carbon storage have been investigated experimentally by using the long core flooding under 8 MPa of pressure and 80 ℃ of temperature respectively.The recovery ratio is between86.92% 98.63%when CO₂ flooding,the CO₂ breakthrough between 0.702 PV 0.879 PV,and the CH₄ recovery ratio is between71.73% 87.56%when CO₂ breakthrough.The CO₂ saturability is about 55%with connate water,while the part dissolved in water is 1.9%PV.Results demonstrate that the smaller displacing velocity is,the faster the CO₂ breakthrough,and the lower the ultimate CH₄ recovers.Besides,the CO₂ breakthrough time is 0.1 PV and 0.17 PV earlier respectively with the scenario of high position injection and low position production of 45° than the opposite scenario of 10° and 45°,and the ultimate recovery of former scenario is 3.3%lower than the latter ones.On the other hand,connate water will cause a delay about 0.11 PV in CO₂ breakthrough and an increase of 3%in methane recovery.With the same injection amount,the lower the permeability is,the faster the CO₂breakthrough,and the lower the ultimate methane recovers.Results show that CO₂ injection into gas reservoirs can enhance gas recovery and implement CO₂ sequestration.Moreover,CO₂ supercritical properties,gravity effect,CO₂ diffusion under low speed and CO₂ dissolution in formation water cannot be ignored.更多还原