Laboratory determination of oil draining CO2 hysteresis effects during multiple floods of a conventional clastic oil reservoir

Determination of hysteresis in relative permeability data is useful in obtaining more reliable predictions of water alternating gas (WAG) enhanced oil recovery performance and accompanying associated storage of CO2. A laboratory-based evaluation of CO2 draining oil has been conducted on reservoir rocks from a conventional clastic oil reservoir undergoing tertiary CO2 enhanced recovery. Experimentation was conducted at reservoir conditions of 16 MPa (2300 psi) and 43 °C (110 °F). Through this study, a better understanding of the oil production and associated storage of CO2 in a conventional clastic oil reservoir has been obtained. Data generated provide an example of a site-specific field project that is currently undergoing a tertiary CO2-based EOR project demonstrating that associated CO2 storage will occur. Through multiple cycles of CO2 injection, this study has shown the effectiveness of first contact CO2 as it relates to the mobilization of oil from injector to producer. Additionally, in this conventional clastic reservoir, CO2 trapping appears to have taken place during the initial imbibition cycle, as oil production and differential pressures remain consistent during subsequent tests.