An application of thickener to increase viscosity of liquid CO2 and the assessment of the reservoir geological damage and CO2 utilization

Abstract

ABSTRACTIn comparison to hydraulic fracturing, CO2 fracturing technology is more efficient and effective in solving environmental problems caused by the fracturing process. However, the low viscosity caused by pure CO2 under high pressure hinders the development of the entire fracturing technology. Given that, a siloxane that can significantly improve the liquid CO2 viscosity is prepared and the excellent performance to thicken CO2 by silicone polymer is shown. Polymerization that occurs under water conditions presents a trend and is more likely to trigger reaction than ring-opening polymerization under anhydrous conditions. The thickening performance test is conducted by capillary viscometer self-designed at 35°C and 10 MPa. Moreover, a rising trend in viscosity is demonstrated with increase in thickener concentration. Smaller damages and chemical residue exists in the stratum after CO2 fracturing. In addition, there are no changes that occur in the quality of crude oil. A fine conclusion for thickening performance provides a basis for the synthesis of the polymer to thicken CO2.