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Title: Field Demonstration of the Combined Use of Thermally-Degrading and Cation-Exchanging Tracers to Predict Thermal Drawdown in a Geothermal Reservoir

Technical Report ·
DOI:https://doi.org/10.2172/1469491· OSTI ID:1469491
 [1];  [1];  [1];  [2]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Cyrq Energy Inc.. Salt Lake City, UT (United States)

This paper presents the results and interpretation of a reactive tracer test in a geothermal reservoir involving a cation-exchanging tracer to interrogate flow pathway surface area to volume ratios and a thermally-degrading tracer to interrogate average flow pathway temperatures. The test interpretations, which are based on comparing the reactive tracer responses to that of a nonreactive tracer, are used to predict when thermal drawdown will occur at the production well due to injecting cooler, spent geothermal water into an injection well. It is shown that the cation- exchanging tracer provides constraints on the timing of thermal drawdown, and the thermally-degrading tracer provides constraints on the magnitude of thermal drawdown. Thus, the combined use of the two reactive tracers provides a better prediction of thermal drawdown than either one alone. Uncertainties associated with the method, including assumptions made about flow pathway geometry, are discussed. It is also shown that interrogating average temperatures along flow pathways using a thermally-degrading tracer at different times can be translated into an estimate of when thermal drawdown will occur without direct knowledge of flow pathway geometry.

Research Organization:
Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Geothermal Technologies Office
DOE Contract Number:
AC52-06NA25396
OSTI ID:
1469491
Report Number(s):
LA-UR-18-28501
Country of Publication:
United States
Language:
English