Assessment of CO2 Flooding Potential for Bakken Formation, Saskatchewan

Abstract

The Bakken is an extremely tight formation, with the oil contained mostly in siltstone and sandstone reservoirs with low porosity and permeability. In Saskatchewan alone, there could be an estimated 25 to 100 billion barrels of Bakken oil in place. At present, the combination of horizontal well drilling and the new multi-stage fracturing and completion technologies has been the key to economically unlocking the vast reserves of the Bakken formation. The primary recovery factor, however, remains rather low due to high capillary trapping. While waterflooding could result in unfavorable injectivity issues, carbon dioxide (CO 2 ) miscible flooding provides a promising option for increasing the recovery factor. Higher oil recovery factor can be achieved with CO 2 injection through multi-contact miscibility that results in vanishing interfacial tension, viscosity reduction, and oil swelling. This paper conducted a numerical simulation work as an effective and economical means of evaluating CO 2 flooding potential for enhanced oil recovery. Different strategies were tested to compare the effects on oil recovery of injection well pattern, continuous and cyclic injection, waterflooding and CO 2 flooding, injected gas composition, and heterogeneity. The simulation results show that CO 2 flooding presents a technically promising method for recovering the vast Bakken oil.

Reservoir simulation and optimization of Huff-and-Puff operations in the Bakken Shale

“…Hoffman [19] studied the injection of hydrocarbon gases in the continuous injection mode, and concluded that ''miscible hydrocarbon injection performs as well as miscible CO 2 .'' Meanwhile, Wang et al [20] found that CO 2 -enriched produced gas (60-40 mol% CO 2 -CH 4 ) and CO 2 -enriched flue gas (60-40 mol% CO 2 -N 2 ) display ''high oil recovery performance'' and would be efficient choices for gas flooding projects in the Bakken. Two cases were run, each consisting of a 4-cycle Huff-and-Puff treatment.…”

Determining Well-to-Well Connectivity in Tight Reservoirs

“…The formation, deposited during Late Devonian and Early Mississipian periods, is overlain by the Lodgepole Formation, an aquifer, and overlays the Torquay Formation (Kreis and Costa, 2005). The Bakken Formation is composed of three members; upper and lower organic-rich black shales, and a middle siltstone to sandstone member (Wang et al, 2010). The reservoir has an initial pressure of 2600 psi and temperature of 156°F (CPE, 2015).…”

Investigation of CO2/N2 injection in tight oil reservoirs with confinement effect

“…This makes CO 2 the best candidate for improving the tight oil recovery . Several studies report that it can achieve an incremental oil recovery in the range of 5%‐20% in the Bakken and Eagle ford reservoirs using the huff‐n‐puff gas process . However, some studies also indicate that CO 2 injection does have several drawbacks, including the rapid decline of oil production.…”

“…2,[15][16][17][18] Several studies report that it can achieve an incremental oil recovery in the range of 5%-20% in the Bakken and Eagle ford reservoirs using the huff-n-puff gas process. [19][20][21][22][23] However, some studies also indicate that CO 2 injection does have several drawbacks, 24,25 including the rapid decline of oil production. Some have reported that the reservoir pressure during production cycle sharply drops after the first cycle with linear depletion to the minimum pressure.…”