Would you use steam injection as an EOR technique in a reservoir with heavy oil? And how heavy does it need to be? More importantly, do you know about the different methods available and how successful certain steam injection techniques can be?
Steam injection is often used in heavy oil fields to heat and increase the mobility of crude oil by lowering its viscosity and vaporizing a small quantity which in turn contributes to increasing flowability. Steam injection can be split into two categories – Continuous Steam Stimulation (CSS), and Steam-Assisted Gravity Drainage (SAGD) (Figure 1).
Analysis in DAKS suggests that on average, steam injection increases ultimate recovery factor by approximately 30%. In some exceptional analogues found in DAKS, such as the Pikes Peak field in Canada, the recovery factor resulting from CSS is estimated to be as high as 70%; up from 4% after secondary recovery (Figure 2). The success here is thought to be due to the high N:G (0.96) homogeneous reservoir, providing excellent vertical sweep with few baffles to flow. This contrasts with the Peace River Arch area in Alberta, Canada where despite a relatively successful CSS project, a second project using SAGD faced issues due to a permeability contrast between higher the reservoir base and the top. As a result, the ultimate recovery factor was 14% at termination of SAGD.
Sedimentological analogues from DAKS aid the understanding of the likely complexity of any given reservoir setting to help geoscientists and reservoir engineers optimize the choice and application of EOR techniques like steam injection.