Performance evaluation of thickener for CO2 flow control
In order to solve the problems of ineffective gas injection and decreased oil displacement effi-ciency caused by CO2 gas channelling in the application of CCUS technology in low permeability reser-voir,YCL-2,a modified copolymerization product of phenyl glycidyl ether and propylene oxide,was select-ed as a CO2 thickener in extremely low permeability reservoir,and the solubility of YCL-2 was observed by visual high-pressure vessel.The rheological properties of YCL-2 at different concentrations and temper-atures were studied by rotating rheometer,and the displacement effect of YCL-2 in core groups with per-meability difference of 5 and 10 was investigated.The plugging ability of cores with different permeability was calculated by using varied-diameter capillary bundle model to simulate the thickener system.The re-sults show that YCL-2 with mass concentration below 2.0%can be completely dissolved in supercritical CO2.Rheological experiments show that the shear resistance of the system decreases with the increase of temperature.The selective injection experiment shows that the system has a certain sealing effect on the small pores of the core,and is suitable for reservoirs with permeability difference less than 5.
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