There is growing interest in the novel concept of operating Enhanced Geothermal Systems (EGS) with CO2 instead of water as heat transmission fluid. Initial studies have suggested that CO2 will achieve larger rates of heat extraction, and can offer geologic storage of carbon as an ancillary benefit. Fluid-rock interactions in EGS operated with CO2 are expected to be vastly different in zones wit...

This paper describes the investigation of a single-well enhanced geothermal system comprised of a downhole thermosiphon and a novel completion design using a downhole heat exchanger. The thermosiphon is a device that takes advantage of the gravity head difference between liquid flowing down the annulus and vapor flowing up the tubing. Without a connection to a large reservoir volume, a downhole...

The thermal stability and adsorption characteristics of three perfluorinated hydrocarbon compounds were evaluated under geothermal conditions to determine the potential to use these compounds as conservative or thermally-degrading tracers in Engineered (or Enhanced) Geothermal Systems (EGS). The three compounds tested were perfluorodimethylcyclobutane (PDCB), perfluoromethylcyclohexane (PMCH), ...

CO2-based enhanced geothermal systems (EGSs) have been examined from a reservoir-oriented perspective, and as a result thermodynamic performance is well explored. Economics of the system are still not well understood, however. In this study, the economics of the CO2-based EGS technology is explored for an optimized power plant design and best-available cost estimation data. We demonstrate that ...

Hydraulic dispersion in porous media and in fracture networks results in the spreading of the timedependent tracer signal. In geothermal reservoirs the wellbore often intersects fractures that are separated by tens or even hundreds of meters. The mixing in the wellbore at those separated fractures is also a source of dispersion, since tracer signals sampled at the wellhead are a mixture of the ...

The characterization of fluid-transport properties of rocks is one of the most important, yet difficult, challenges of reservoir geophysics, but is essential for optimal development of hydrocarbon and geothermal reservoirs. Production of shale oil, shale gas, heavy oil and geothermal energy, as well as carbon-dioxide sequestration, are relatively recent developments where borehole fluid injecti...