Experimental study of secondary and tertiary CO2 injection at above MMP conditions

Carbon dioxide (CO2) injection is the most popular gas injection method to increase oil recovery efficiency from oil reservoirs. However, direct CO2 injection has a lot of problems such as early breakthrough and viscous fingering that leads to poor sweep efficiency. To reduce these problems, tertiary CO2 injection is suggested.This paper describes the experimental results of CO2 injection after and prior to water flooding.. That is, in the first test, injection of CO2 after oil flooding and in the second test CO2 was injected after water flooding. These tests were carried out using core flood apparatus with real crude oil type. The experiments have been conducted at pressure of 13.7 MMPa (2000 psi) and temperature of 313 K (40 °C). The pressure was set to be above the minimum miscible pressure of the crude oil and CO2.The results show tertiary CO2 injection has higher recovery than secondary CO2 injection. This could be due to improvement of the mobility of the injecting fluid, that would eliminate early breakthrough. Asphaltene precipitation during secondary CO2 injection could be another reason of low oil recovery.

Experimental study of secondary and tertiary CO2 injection at above MMP conditions Keywords:

CO2 injection , core flood , Secondary , Tertiary