Distribution of CO₂ in fractured carbonate reservoirs

Abstract

Deep geologic injection of supercritical carbon dioxide (CO 2 ) for enhanced oil recovery (EOR) has been widely used for improved oil recovery from depleted oilfields since early 1970s. The CO 2 injection maintains the pressure, mobilize the oil and release the petroleum resources that would otherwise be inaccessible. In addition to improving the oil recovery, the CO 2 -EOR contributes to minimize the impact of CO 2 -emissions to the atmosphere. The injected CO 2 will be remained trapped in the underground geological formations, as the CO 2 replace the oil and water in the pores. Carbonate reservoirs are characterized by low permeability and high heterogeneity, resulting in early breakthrough of gas and water and hence low oil recovery. The presence of naturally fractures in carbonate reservoirs is a major problem for the oil industry using CO 2 -EOR, because significant amount of CO 2 are recycled to the well, and thereby not distributes in the reservoir. This study focuses on CO 2 injection into a naturally fractured carbonate reservoir, including near-well simulations of CO 2 -distribution in the rock matrix. The simulations are carried out using the reservoir simulation software Rocx in combination with OLGA. The simulations show that CO 2 -injection into a naturally fractured carbonate reservoir in combination with closing of the fractured zones result in good distribution of CO 2 in the reservoir.

Simulation of Oil Production from Homogenous North Sea Reservoirs with Inflow Control using OLGA/Rocx

“…(Furuvik and Moldestad, 2017;Tangen, 2017) Swc defines the maximum water saturation that a reservoir can retain without producing water, and Sor refers to the minimum oil saturation at which oil can be recovered by primary and secondary oil recovery. The relative permeability curves implemented in the simulations are presented in Figure 5.…”

“…The blue line represents the relative permeability for water (Krw) and the red line represents the relative permeability for oil (Kro). The calculation and implementation of the relative permeability curves in Rocx, is described in detail by Furuvik and Moldestad (Furuvik and Moldestad, 2017).…”

“…Several studies have been carried out to investigate the effect of inflow controllers in different types of reservoirs. (Furuvik and Moldestad, 2017;Ugwu and Moldestad, 2016;Abbasi and Moldestad, 2016;Jonskås et al, 2016) Near-well simulation have been performed by using simulation tools like Eclipse, OLGA/Rocx, Aspen/Hysys and NETool. The conclusion has been that there is a high potential of increasing the oil recovery by using inflow controllers.…”

Simulation of Oil Production from Heterogeneous North Sea Reservoirs with Inflow Control using OLGA/Rocx

“…The required input data is limited to the irreducible water saturation (Swc) and the residual oil saturation (Sor), and their corresponding relative permeabilities. (Furuvik and Moldestad, 2017;Tangen, 2017) Swc defines the maximum water saturation that a reservoir can retain without producing water, and Sor refers to the minimum oil saturation at which oil can be recovered by primary and secondary oil recovery. The relative permeability curves implemented in the simulations are presented in Figure 6.…”

“…AICV can close for unwanted fluids when breakthrough occurs. The effect of inflow controllers in different types of reservoirs has been studied by several researchers (Furuvik and Moldestad, 2017;Ugwu and Moldestad, 2016;Abbasi and Moldestad, 2016;Jonskås et al, 2016;Wijerathne and Halvorsen, 2015;Aakre et al, 2013) by using simulation tools like OLGA/Rocx, Eclipse, NETool and Aspen/Hysys. The conclusion has been that there is a high potential of increasing the oil recovery by using inflow controllers.…”