Oil and Gas Resources, Kopanoar Play, Beaufort Sea

K.J. Drummond
Calgary, Alberta

The Beaufort Sea has a large resource of discovered oil and gas and a very significant potential for future undiscovered oil and gas. The Kopanoar play is one of the more important plays in the Beaufort Sea, with discovered resources of 234 MMB of recoverable oil and 822 BCF of recoverable gas. The mean undiscovered potential is estimated to be 1,866 MMB of recoverable oil and 7,044 BCF of recoverable gas.

The Kopanoar play area and the adjacent play areas are shown in Figure 1. The southern margin of the Kopanoar play is the shelf-to-slope transition of Oligocene strata. The play extends northward beneath the outer portions of the modern shelf. The northern limit is arbitrary and is drawn at the present day shelf edge. The play area is entirely offshore in water depths between 60 and 100 metres.

The Kopanoar play area includes two plays, the Kugmallit play and the Mackenzie Bay play, shown in Figure 2. The Kugmallit is the primary play and includes all pools and prospects within deep water sandstones deposited on the continental slope and basin plain. The principal reservoirs of the Kugmallit play are in Upper Kugmallit slope sandstones and Kugmallit basin floor submarine fan deposits. The Kugmallit play includes sandstones of the deeper Richards sequence. The Mackenzie Bay play is characterized by slope to basinal facies, mainly shale with some sandstone.

Potential reservoir sections in the Kugmallit comprise packages of thinly bedded sandstone up to several hundred feet in overall thickness. Pools of the Upper Kugmallit sequence have reservoir sandstones between 20 and 98 feet thick, with an average porosity of 19 per cent. For the Mackenzie Bay sequence pools have net pays of 8 to 49 feet, with average porosity of 22 percent. The larger fields contain numerous stacked pools. Thick interbedded shales and the overlying Mackenzie Bay shale succession provide a good seal. In general, Kugmallit reservoirs are overpressured.

The majority of traps in the play are structural. The Kopanoar play area is characterized by easterly trending folds of the Beaufort Fold Belt. The Beaufort Fold Belt involves Upper Cretaceous to Miocene strata. Principal trap type is structural drape over the pre- Richards fold belt of late middle Miocene age. Stratigraphic plays off the flanks of these folds could also be important.

Exploration began with the spudding of Dome et al Nektoralik K-59 and Hunt Dome Kopanoar M-13 in the summer of 1976. During the years 1976 to 1984 a total of 15 wells, listed in Table 1, were drilled in the play, with seven successful wells, resulting in the issue of 6 Significant Discovery Licences, for a success rate of 47%. Four other wells had shows of oil/and or gas on drill stem test and only four wells had no occurrence of oil or gas. The last well drilled was Dome Nerlerk J-67, drilled and abandoned in 1984.

The oil and gas resources for the discovered fields of the Kopanoar play area are listed, ranked by oil equivalent in Table 2. The largest field on an oil equivalent basis is Koakoak, followed by Kopanoar. The total discovered recoverable resource is 234.1 MMB of oil and 822.5 BCF of gas, for a total oil equivalent of 376.6 million barrels

The estimated ultimate recoverable oil and gas resources for the Kopanoar play area of the Beaufort Sea are shown in Figure 3. The ultimate recoverable oil resource is estimated to be 2,100 million barrels, of which 1, 866 million barrels (87%) remains to be discovered. The ultimate recoverable gas resource is estimated to be 7,867 billion cubic feet, of which 7, 044 billion cubic feet (89.5%) remains to be discovered.

Table 1. Kopanoar Play Area, Beaufort Sea List of Wells Drilled.