Large reserves of heavy bitumen (ρ10 deg API) exist in shallow, unconsolidated sandstone formations in central and western Alberta. The McMurray, Grand Rapids, Clearwater and Wabiskaw Cretaceous Manville sands comprise the majority of the heavy oil producing zones of this type. Cyclic steam injection, steam drive and steam assisted gravity drainage (SAGD) are used extensively in this area to produce heavy bitumen at depths where surface mining is impractical. The water-oil relative permeability characteristics of these formations strongly control the ability to inject hot water and/or steam, and the overall conformance and recovery of bitumen from the formations. This paper reviews an extensive database of reservoir condition water oil relative permeability data conducted at temperatures from 10 to 275 °C and presents correlations to estimate water-oil relative permeability character and residual oil saturations for preliminary evaluation purposes to aid in the high level screening of potential future projects in these formations.
The worlds largest remaining known reserves of liquid hydrocarbons are contained in the shallow, unconsolidated Cretaceous period Manville sands in central and eastern Alberta. Some of these deposits exist at shallow depths that allow the recovery of the sand using direct surface mining and the subsequent extraction of the bitumen from the mined sand. However, large portions of the bitumen are buried at depths too great for economic mining operations. To extract the heavy bitumen from these zones, a number of in-situ thermal techniques, such as cyclic steam injection, steam drive and steam assisted gravity drainage (SAGD) have been successfully used. The multiphase flow interference effects associated with steam, steam condensate and bitumen moving concurrently through the pore system is represented by relative permeability curves. As such, these curves play a very large role in determining the speed, efficiency and ultimate economics of a thermal recovery process.
Very little regressed relative permeability data on unconsolidated sands, with the exception of a study by Frizzell(1), have been presented in the literature. A number of authors (2–6) have described and discussed high temperature relative permeability measurements for unconsolidated heavy oil sand systems. However, considerable controversy exists with some authors (7–12) suggesting that temperature does not play a role in the relative permeability of heavy oil systems, while others (13–18) claiming that there are strong temperature effects.
This study examined a specific subset of low and high temperature waterflood and steamflood tests that were conducted on unconsolidated cores over a 15 year period. A total of 43 different studies were analyzed, all of which were conducted on samples taken from the heavy oil producing regions in central and eastern Alberta and western Saskatchewan in the western Canadian sedimentary basin. All of the samples tested had the following common characteristics;
All samples were preserved state core that had been frozen on site immediately after coring to prevent oxidation and core disturbance.
Over 90% of the samples tested were sourced from the McMurray sandstone formation, hence the correlations resulting from this work have specific application to McMurray sandstone formation production zones.
