Peter E. Rose¹
(1) Energy and Geoscience Institute at the University of Utah, Salt Lake City, UT

Abstract: The application of novel tracers in the modeling of fluid flow in a fractured reservoir

A new family of fluorescent compounds, the polyaromatic sulfonates, has been found to be conservative, very detectable, environmentally benign, and quite affordable when used in both geothermal and ground water tracing environments. Using conventional reversed phase High Performance Liquid Chromatography with ion pairing reagents and fluorescence detection, limits of detection for these compounds were determined to be approximately 200 parts per trillion.

In a series of tracer tests at the Dixie Valley, NV, geothermal reservoir, the polyaromatic sulfonates were used to determine the flow patterns of water injected via five injection wells. The tracer data were used to calibrate the finite element code, GEOCRACK3D, which is a fully coupled structural-deformation, fluid-flow, heat-transfer computer model developed by Daniel Swenson and co-workers at Kansas State University. It simulates flow through explicitly defined fractures with apertures that respond dynamically to the reservoir stress state and to fluid pressures. In addition, it provides for the modeling of tracers that can be conservative, adsorptive, or thermally decaying.

The candidate tracers were successfully tested in other geothermal reservoirs in the U.S., New Zealand and Indonesia. In a field study at the INEEL Radioactive Waste Management Center near Idaho Falls, 1,5-naphthalene disulfonate was successfully used as a ground water tracer to evaluate the conductivity of unconsolidated sedimentary layers interbedded between fractured basalt layers in the vadose zone. The polyaromatic sulfonates also have potential for use as water flood tracers.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana