Experimental study on CO2 storage capacity of high-dryness foam in heterogeneous saline aquifers
CO2 storage in saline aquifers is an important technical means to achieve the goal of"carbon neutrality".High-dryness foam can not only control CO2 mobility,but also adapt to heterogeneous reservoirs,so it can improve the space utilization efficiency of saline aquifers.In order to explore the profile control effect and CO2 storage capacity of high-dryness CO2 foam in heterogeneous saline aquifers,this paper performs laboratory experiments to study CO2 foam displacement in parallel cores with different permeability contrasts by using our independently designed high-temperature and high-pressure displacement experiment device.In addition,the gas and liquid production situations and the change laws of CO2 saturation in the cores during the displacement process are analyzed,and the carbon storage effects and mechanisms in heterogeneous core model with different permeability contrasts are revealed.And the following research results are obtained.First,compared with CO2 flooding,high-dryness foam flooding is more advantageous for saline aquifer CO2 storage.When the permeability contrast of the cores is in the range of 2.6-10.8,foam can effectively block the high-permeability cores and maintain the resistance factor at about 36,so as to increase the displacement pressure difference and the gas and liquid production rates of low-permeability cores.Second,there is a certain relationship between gas saturation and permeability of cores.When the permeability is less than 2 450 mD,the highest gas saturation increases with the increasing of permeability.When the permeability exceeds 2 450 mD,the highest gas saturation is about 80%.Third,high-dryness foam flooding can effectively expand the CO2 storage volume in the cores.When the permeability contrast is 4,the CO2 storage volume by foam flooding is 219%larger than that by gas flooding.When the permeability contrast is high up to 10.8,the CO2 storage volume can be maintained at a high level all the time.In conclusion,the CO2 foam displacement experiments under saline aquifer conditions show the change of CO2 storage capacity and provide an experimental understanding on the improvement of carbon storage efficiency in heterogeneous reservoirs.The research results provide reference and guidance for the technological optimization of CO2 geological storage in heterogeneous saline aquifers.
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