ALBERT

Description: The Stochastically Perturbed Parametrisation Tendencies (SPPT) scheme is used at weather and climate forecasting centres worldwide to represent model uncertainty that arises from simplifications involved in the parametrisation process. It uses spatio-temporally correlated multiplicative noise to perturb the sum of the parametrised tendencies. However, SPPT does not distinguish between different parametrisation schemes, which do not necessarily have the same error characteristics. A generalisation to SPPT is proposed, whereby the tendency from each parametrisation scheme can be perturbed using an independent stochastic pattern. This acknowledges that the forecast errors arising from different parametrisations are not perfectly correlated. Two variations of this ‘independent SPPT’ (iSPPT) approach are tested in the Integrated Forecasting System (IFS). The first perturbs all parametrised tendencies independently while the second groups tendencies before perturbation. The iSPPT schemes lead to statistically significant improvements in forecast reliability in the tropics in medium range weather forecasts. This improvement can be attributed to a large, beneficial increase in ensemble spread in regions with significant convective activity. The iSPPT schemes also lead to improved forecast skill in the extra tropics for a set of cases in which the synoptic initial conditions were more likely to result in European ‘forecast busts’. Longer 13-month simulations are also considered to indicate the effect of iSPPT on the mean climate of the IFS.

Description: Using the data from over 8000 wells augmented by seismic and thermal response information, a comparison of McMurray Formation (Cretaceous) and Grosmont C member (Devonian) thermal recovery reservoirs of northeastern Alberta is provided along with a discussion of reservoir performance to date. Fluvial-estuarine McMurray Formation reservoirs perform best where bitumen-charged homogeneous lenticular sandstones at least 20 metres thick are found. These deposits are relatively rare as the formation is characterized by endemic heterogeneity mainly in the form of inclined heterolithic stratification (IHS). Most of the best McMurray steam-assisted gravity drainage (SAGD) reservoirs appear to be currently on-line and produce approximately 113 000 m 3 /day of bitumen from fourteen projects. Platform carbonate Grosmont C successions are blanket deposits 32–35 metres thick, with bitumen columns typically 15–24 metres thick, and are characterized by consistent reservoir properties facilitated by pervasive multi-scale fracturing. Although no reserves have yet to be assigned to Alberta’s bitumen-bearing carbonates by the province, recent pilot results derived from cyclic steam stimulation (CSS) operations suggest that Grosmont C reservoir performance could ultimately prove to be competitive with superior McMurray SAGD reservoirs. Under current technological and economic conditions, McMurray SAGD reservoirs appear incapable of providing the 15.9 billion m 3 of in-situ bitumen reserves (59% of Canada’s total oil reserves) ascribed to this formation by the province of Alberta as only circa 6 billion m 3 of oil-in place appears to reside within optimal reservoirs (i.e. those reservoirs at least 20 metres thick with average porosity and oil saturation values of 33% and 80%, respectively). Barring future technological breakthroughs and, or, economic improvements, future commercial development of both the Grosmont C and other carbonate reservoirs might be needed to make up for some of the potential reserve shortfall associated with McMurray Formation SAGD reservoirs.