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The "Soaker Hose" concept for SAGD injectors has long been a topic of interest for oil sands development, but few field trials have been attempted to date. The primary interest in this type of design is its potential to produce more uniform injection distributions, but other more elaborate solutions have garnered interest from the industry. Another, less prominent feature of the soaker hose concept is its potential for reducing well completion cost. In the current economic climate, the need for controlling cost has become paramount, which could make this design concept a subject of renewed interest for the industry. The basic premise of the soaker hose concept is to deliberately increase the radial flow resistance through the liner so that it dominates the overall flow resistance relative to the axial flow resistance in the wellbore, with a consequent reduction in radial flow variation. Some examples exploring the concept have been reported (e.g. Stalder, 2012). The performance interpretation is a product of the assumptions made to estimate the radial flow distribution, in particular the ideal formation conditions into which injection occurs. Modelling developments focused specifically on the SAGD process can shed new light on completion performance and provide more rigorous bases for optimizing completions that account for factors beyond wellbore hydraulics, including variances in drilling and reservoir performance. This paper presents results of SAGD modelling for various injector completion designs to quantify the potential for optimizing the recovery process. The Mechanistic SAGD Model incorporates coupled injector/producer wellbore hydraulics with essential reservoir flow models to simulate SAGD conformance. It uses reservoir performance as input for directly calculating the liquid level distribution produced by the injector/producer completion configuration in the specific reservoir context. In this set of case studies, some variations on the soaker hose theme are included, and completion options for addressing examples of non-ideal reservoirs through reservoir-specific optimization of the injector design are considered. The cost saving potential for the various completion options is also discussed. |
