Simultaneous CO2 Huff-n-Puff Test in Highly Sensitive Reservoirs in Upper Wuerhe Formation,Mahu Sag
In order to explore the post-fracturing EOR technologies for efficient development of highly sensitive tight conglomerate oil reser-voirs in horizontal wells in the Mahu sag,a simultaneous CO2 huff-n-puff test was carried out in the Mahu 1 well block.The results show that simultaneous CO2 huff-n-puff can enhance oil recovery of highly sensitive tight conglomerate reservoirs,and its oil displacement mech-anisms mainly include extraction,miscibility,competitive adsorption,and expansive displacement.Fracture communication is the main cause of gas channeling.Through field regulation and control,synchronous soaking of well groups and gas channeling wells was achieved,ensuring the field implementation effect.Soaked by fracturing fluid,the clay minerals in the tested well group hydrate and expand,causing pore throat blockage,which affects CO2 swept range and results in a low interim oil exchange ratio.The simultaneous CO2 huff-n-puff test achieved favorable stimulation effects,with an interim oil increment of 3,983 tons and an oil exchange ratio of 0.36 in the tested well group.This test provides technical ideas and field experience for horizontal wells in enhancing oil recovery of highly sensitive tight conglomerate reservoirs after fracturing.
Mahu sagupper Wuerhe formationtight conglomeratesimultaneous CO2 huff-n-puffsensitivityEOR
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