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Enhancement of heat production through selective scaling

Technical Report ·
DOI:https://doi.org/10.2172/6830504· OSTI ID:6830504
The heat-depleted brine has to be reinjected whether it is for technical, economical, environmental and/or legal purposes. However, there are many problems related to injectivity and injectability in a geothermal field. The major drawback is the dread of an early breakthrough of the heat depleted brine at the production wells. It is believed that this drawback may be overcome through selective scaling. The results of investigation into the feasibility of selective scaling are summarized. Selective scaling is defined here as the process of intentionally precipitating large quantities of chemical compounds at selected locations, such as high permeability streaks or fractures, for the purpose of retarding the flow of injection fluids through these flow channels. Such flow retardation will increase the residence time of the injected fluids in the reservoir by a more suitable heat sweep thereby enhancing the heat extraction from the geothermal reservoir. Three different methods of selective scaling are discussed. These methods are: the injection of a thermodynamically unstable brine; injection of a slug of dirty brine or other thermodynamically unstable brine into selective locations of the reservoir; and mixing of an injection brine which is incompatible with a reservoir brine. The basis of these methods and their impact on the permeability characteristics of the reservoir are discussed through a precipitation model and through simple flow models. The application of these models are illustrated using Salton Sea brine and Currier 2 brine.
Research Organization:
Vetter Research, Costa Mesa, CA (USA)
DOE Contract Number:
AC03-78ET27146
OSTI ID:
6830504
Report Number(s):
DOE/ET/27146-T16; ON: DE82021792
Country of Publication:
United States
Language:
English