Reservoir upgrading of bitumen and heavy oils may involve the use of moderate to high temperatures (200-350 degrees C). In the absence of an efficient catalyst that could help split or transfer hydrogen to cracked heavy molecules, these would deteriorate to form denser asphaltenes with high aromaticity typical from thermal cracldng. The tendency of these molecules to flocculate/precipitate inside the porous media and eventually impair oil production needs to be investigated. Perhaps in an opposite direction, the reservoir porous media may also offer a way of selectively retaining the incipiently deteriorated asphaltenes, thus avoiding early media plugging. Attending to these issues, adsorption studies of virgin (VR) and visbroken (VB) vacuum residue with a conversion of 28.5 wt % (28.5% VB) from Athabasca bitumen were carried out using Athabasca reservoir core minerals (well 14-27-88 11W4) spanning depths from 264 to 308 m. Adsorption experiments were performed in toluene solutions of the adsorbates, monitored via ultraviolet-visible (UV-vis) spectrophotometry to determine the uptake over each core sample. It was found that the Athabasca core is extremely heterogeneous; therefore, different uptakes were observed. These uptakes were correlated with core depths, surface areas, H/C atomic ratio, and nitrogen content. Correlations of the former parameters with adsorption uptakes were found to be useful for predicting the adsorptive capacity of the cracked products over the studied core samples.