Abstract

The integrity of Steam-Assisted Gravity Drainage (SAGD) wells are often threatened by the very steam that provides the process its name. High rate steam production, or the adiabatic flashing of steam condensate to a vapor state, often creates an environment of "flashing erosion", erosive damage created by the water-cutting effect of high velocity wet steam or the corrosive elements (e.g., carbonic acid) that can be associated with low temperature condensate. Condensate flashing to steam also carries additional risk from "cavitation erosion", erosion of completion equipment that occurs from the sudden shock wave impacts caused by the implosion of small liquid-free zones with the condensate, similar to the well- understood water hammer effect. Conventionally, to prevent the production of live steam or the flashing of steam condensate, operators have relied upon choking production rates based upon monitored temperature differences between injected and produced fluids. However, this methodology based on subcool carries its own risks and undermines the economic viability of SAGD projects. Another approach is to improve conformance of steam injection and fluid production by installing inflow/injection control devices (ICDs) in either, or both, the SAGD injector and producer. If properly designed, these devices in the producer can equalize heel-to-toe influx of bitumen emulsion, provide greater control of the sub-cool, and behave as an autonomous (or self-regulating) valve. This presentation will focus upon this last design objective. By coupling published performance equations for various ICD designs with steam behavior equations, competing designs will be evaluated for their likelihood of steam flashing within a SAGD completion and their respective ability to control flashed steam prior to the steam creating damage in the completion. Further, the discussion will examine possible future avenues of research, such as ICD designs with a steam throttle effect driven through a velocity-sensitive choking of steam production.

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