There exists high uncertainty in modelling an interbedded shale barrier in heterogeneous oil sands reservoir, which causes a critical impact on SAGD performance. At present, despite the rise of research on shale barrier issues, few studies have attempted to address the prediction of shale barrier size except for 4D seismic data interpretation. In a shale interbedded oil sands reservoir, the SAGD production data such as the oil rate and steam-oil ratio (SOR) increase up to a peak point and decreases down to a trough point again, and the points are named inflection points (IP).

In this study, proxy models were developed for predicting the shale barrier size using reservoir parameters and the IP of SAGD production data. In addition, a field application was carried out for verification of the developed proxy models using the data from Suncor's Firebag SAGD project, Alberta, Canada.

The results of the screening analysis showed that the key parameters affecting IP of the SAGD production data were the reservoir thickness, horizontal permeability, vertical-horizontal permeability ratio, oil saturation, shale width (WD), shale length (LN), and vertical location of the shale (VL). The key parameters were selected and multiple simulation cases were generated using a latin hypercube sampling. As a result, the applicable proxy models for predicting WD, LN, and VL were developed by statistical analysis of the reservoir parameters, shale size and location, and IP. The statistical results of the proxy models show that the adjusted R-squared and predicted R-squared are high.

As a verification procedure, 3-D simulations were performed to reconstruct the predicted WD, LN, and VL, and the oil production profiles of the field well pairs were compared with the simulation results of the reconstructed shale barrier.

The oil production profiles show the similar trend between the simulation results of the reconstructed model and the field SAGD production data. Therefore, the developed proxy models can predict the shale barrier size properly, and may be useful for the field application.

You can access this article if you purchase or spend a download.