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Members SPE-AIME Abstract CLD Technology, Inc. is developing additives to steam which are intended to increase both the economics and the amount of oil recovered in steam injection operations. CLD's initial project was started under a contract with the U.S. Department of Energy in October 1979 for the express purpose of developing and demonstrating the efficiency of "foam blocks" to increase the efficiency of the steam drive. After extensive laboratory research and development and five field tests, it can now be concluded that the efficiency of the steam drive can indeed be increased in particular reservoirs by the use of the proper additives. Continued research has demonstrated that the particular additives being developed do alter injection profiles and increase the ability of steam to transport the heated crude oil. Employing a hypothesis concerning the mechanism by which oil is displaced by steam, superior additives have now been developed based on the results of laboratory screening tests. Introduction Early production of hot water and/or steam from wells offsetting the injection well is an inherent characteristic of steam drive operations. Without such early break-through, rapid and sustained heating of the reservoir and, therefore, sustained oil production, would not be achievable. production, would not be achievable. Just as such early breakthrough is intrinsic to the process, so is the restricted efficiency of the process itself. The steam, because of its low density and low viscosity, overrides the oil column, Fig. 1, and speeds through the reservoir. The stratified flow of the steam vapor, as would be the case for any injected gas, is inefficient in displacing the heated oil. The inefficiency of the process is further exacerbated by process is further exacerbated by lithological and saturation heterogeneities as in the case of any other enhanced recovery process, but perhaps somewhat less so since the influence of steam can reach out as a result of thermal conduction. CLD's work has been aimed at developing additives to steam and procedures for employing them which would increase the efficiency of steam in displacing crude oil despite the problems posed by the adverse effects of gravitational and viscous instabilities. Initially, CLD, working under contract to the United States Department of Energy, attempted to develop "foam blocks" that would cause diversion of the steam into unswept reservoir volumes. More recently, CLD has emphasized the ability of the additives to promote the transport of heated oil although promote the transport of heated oil although changes in the profile of injected steam appear to accompany the enhancement of the displacement process by the preferred additives. Early Laboratory Work The early laboratory work done under the U.S. D.O.E. Contract has already been described. It comprised the following:Static Foam Tests. Commercially available chemicals were screened to evaluate their ability to form stable foams at elevated temperatures.Laboratory Sandpack Tests. Selected chemicals from the group tested above were evaluated for their ability to develop higher than normal pressure gradients when injected simultaneously with nitrogen into water saturated sandpacks. |
