Importance of Reservoir Description In Evaluating In-Situ Recovery Methods For Cold Lake Heavy Oil

Abstract

Abstract The huge reserves of heavy oil in Alberta are found in a Variety of complex reservoir. Recovery, excluding mining, will require application of some form of in-situ method, primarily in the better reservoir. The proper selection of an in-situ method, applicable to the various reservoir type, requires a basic understanding of reservoir description, and the engineering aspect of the reservoirs. In Part 1 of this paper, reservoir description in the Cold Lake heavy oil deposits is discussed under three headings:rock properties;fluid saturation; andreservoir geometry. Based on these parameters, five selected reservoir types are discussed and compared. Part 2 considers the application of the reservoir description in evaluating in-situ methods. The significance of the reservoir parameters is discussed in general terms and related to the four most important in-situ recovery mechanism: steam stimulation, steam drive, combustion and solvent. The reservoir description is then used as the basis of comparison of the recovery mechanisms for each of the five Cold Lake reservoir types described in Part 1. Introduction OVER 900 BILLION BARRELS (143 × 109 m3) of heavy oil, known as the Alberta oil sands deposits, are found in a variety of complex reservoirs in sands of Lower Cretaceous age. Knowledge of the presence of these resources may be very comforting in these times of concern over Canada's future energy supplies. However, this oil is only of value if, and when, it can be recovered from the reservoirs. Recovery has started in the Athabasca area where oil is being extracted from the reservoir by 'surface mining methods. Great Canadian Oil Sands Ltd. has a mine and an upgrading plant in operation and Syncrude Canada Ltd. has the second extraction facility under construction. Mining methods, however, are applicable to but a small portion of the Athabasca areas and these methods may yield, as currently estimated, 38 billion barrels (6 × 109 m3) or 4% of the total oil in place in the deposits*. The remainder of the oil in place outside of the mineable area of Athabasca, the heavy oil deposits in the Cold Lake area and the other oil sands deposits will have to be extracted by in-situ recovery techniques. In-situ recovery processes basically consist of increasing the mobility of the oil and then driving the fluids to a production well. The successful application of any of these techniques depends on a profound knowledge of the characteristics of the reservoir. Part 1 of this paper discusses the nature of the oil sands in terms of rock properties, fluid saturations and reservoir geometry. Based on these parameters, five selected reservoir types in the Cold Lake area are identified and compared. In Part 2, those parameters are related to a number of in-situ recovery methods for heavy oil, with specific reference to application in the Cold Lake deposit. In the papers, no distinction is made among the terms "heavy-oil sands", "oil sands" or "tar sands".