Active Tracers for Hydraulic Control of Cooled Short Circuits

Abstract

Commercially successful geothermal systems require balance between thermal and hydraulic performance. An injector-producer well pair with exceptional hydraulic performance, for instance, may have inadequate thermal performance if the effective heat transfer surface area is insufficient. In such a circumstance the current state-of-the-art is to abandon such well pairs once production well temperatures fall below design/operating criteria. Here, the concept of an active tracer is introduced as a novel solution that enables cooled short circuits to be sealed off and circulating fluids to be redirected to hotter flow paths. This treatment increases the effective heat transfer area and subsequently improves thermal performance by increasing production well temperatures. The basic principle is introduced and the anticipated improvement to thermal performance is determined from a hypothetical case in which inlet-outlet short-circuiting causes rapid thermal breakthrough in a non-uniform, two-dimensional fracture. Finally, progress on the development of the active tracer is given.