TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA novel numerical analysis is described, in which the steamassisted gravity drainage (SAGD) recovery process in bituminous oil sand is studied. A geomechanical/reservoir simulator was modified to incorporate the absolute permeability increases resulting from the progressive shear dilation of oil sands. The objective was to obtain a realistic prediction of shear dilation, as the oil sands approached failure and beyond, and the concomitant increases in permeability.

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractA novel numerical analysis is described, in which the steamassisted gravity drainage (SAGD) recovery process in bituminous oil sand is studied. A geomechanical/reservoir simulator was modified to incorporate the absolute permeability increases resulting from the progressive shear dilation of oil sands. The objective was to obtain a realistic prediction of shear dilation, as the oil sands approached failure and beyond, and the concomitant increases in permeability.

IntroductionDuring the recent AEUB Chard Leismer Gas Over Bitumen Hearing, there was a considerable amount of technical evidence presented on a wide variety of SAGD technology. One aspect that was different from the last such hearing (Surmont) was the introduction of geomechanics related to the SAGD process. The purpose of this article is to outline the underlying concepts behind geomechanics and then to demonstrate that geomechanics are necessary for a consistent description of SAGD design and actual field performance.

Development of a retrograde condensate reservoir required accurate well productivity predictions for a capital commitment to gas processing facilities. Historically, Fussell identified that liquids condensing in the reservoir will result in a substantial productivity impairment. A single well model, which included a hydraulic fracture as part of the grid system, was developed to perform sensitivities for well test interpretation and to predict long term performance. Interesting results were obtained. The productivity of fractured wells was not impaired to the degree expected. Radial modelling confirmed the results obtained by Fussell. Current simulation technique allows for direct modelling of a hydraulic fracture instead of using an equivalent well bore radius. The distribution of pressure drawdown and condensate dropout around a hydraulic fracture results in limited productivity impairment. The methodology used and the results obtained are described. Introduction This work was originally completed to forecast production from wells in a new field, which was being developed in the Deep Basin area of Alberta, Canada. The original study was comprised of geological characterization, PVT characterization, numerous well test sensitivities, as well as simulating the effects of condensate dropout on well productivity. The ultimate objective of this work was to make a nomination for a sour gas plant. Abbreviation Due to space limitations, this paper represents an abbreviation of only the most important technical point: that for wells that are hydraulically fractured productivity is not as adversely affected by condensate precipitation as previously reported. This is with some regret on behalf of the authors who, as practising engineers, find the approach (or story) to be of as much interest as the actual result. In particular, about two thirds of the real work in this study was confirming formation permeability and fracture properties. To do this, interpretations from various disciplines of petroleum engineering, such as hydraulic fracture treatment monitoring, well test interpretation and core analysis, had to resolved. Justifying, explaining and communicating this input was a significant portion of the work on this project. Organization The paper has still been organized, as much as possible, to follow the historical development of the technical work. Material is presented under the following headings: Geological Description, PVT Characterization, Model Construction, Well Test Modelling, Effects of Condensate Dropout, and Conclusions. Originally this work was completed for a single well, which was later expanded to include other wells in other pools. Only the work done on the first well analyzed is presented, which does not apply universally to the area. P. 177

The author has worked on a number of fractured reservoirs in Western Canada, which show common characteristics. Production performance, pressure transient responses and stimulation results are discussed. A reservoir characterization is presented which is consistent with observed production performance, pressure transient responses, production logging results, core analysis and well stimulation. A key component is structural geological style. This description has been applied to a number of different reservoir situations. It has application to stimulation design, predicting reservoir performance, numerical simulation and pressure transient analysis. An example is also highlighted from a gas condensate reservoir. FIGURE 1: Core porosity vs. core permeability. Alberta Central Foothills Carbonate Reservoir all samples.