Effect of Liquid CO2 Injection on Rheological Properties of Crude Oil

In recent years, due to the lack of water resources and environmental protection reason, less water and dry fracturing technology has been paid more and more attention by oil companies. CO2 foam fracturing technology and liquid CO2 fracturing technology have been carried out in many oilfields. During the contact process of low temperature liquid CO2 with formation rock, crude oil and formation water, the temperature of injection section should be changed, and at the same time, the crude oil performance should be changed too. In this paper, a method of testing the rheological properties of crude oil under different temperature, pressure and CO2 injection rate is established by the modification of rotary viscometer. It is found that the sensitivity of crude oil to temperature disappear and the fluidity is improved with the addition of CO2. However, with the increase of CO2 addition, the viscosity of crude oil decreases rapidly, and the recovery of low temperature formation temperature is slow, which requires a long shut in time.