Experimental study on influence of carbon dioxide content on natural gas properties

The constant composition expansion experiments on natural gas with CO2 content of 10%,30%,50%,70%,90%,100% under three different temperatures (20 ℃,30 ℃,40 ℃) are conducted respectively.The results show that with the CO2 content increasing from 10% to 100%,the critical temperature of natural gas samples increases from -69.86 ℃ to 31.4 ℃,and the critical pressure increases from 4.85 MPa to 7.38 MPa.When the temperature and pressure is constant,with the increasing of CO2 content in natural gas,the relative volume of natural gas samples shows an increase,and with the decreasing of pressure,the volume expansion law of natural gas samples with different CO2 content shows a similar phenomenon in the supercritical CO2 characteristics.This cognition is significant for the further study on oil displacement by mixture of CO2 and natural gas.