Mining Heat


Heat emanating from the Earth’s core could replace a substantial percentage of the energy currently produced by burning gas, oil and coal for electricity generation. The Earth’s heat is an inexhaustible resource whose use creates almost no greenhouse gas emissions. It is, in short, a nearly perfect solution to the world’s energy needs. But before the world can take advantage of this abundant supply of heat, there are daunting economic and technological hurdles to clear.


Craig Beasley Rio de Janeiro, Brazil


Bertrand du Castel Tom Zimmerman Sugar Land, Texas, USA


Robert Lestz Keita Yoshioka Chevron Energy Technology Company Houston, Texas


Amy Long Singapore


Susan Juch Lutz Salt Lake City, Utah, USA


Kenneth Riedel


Chevron Geothermal Indonesia Ltd Jakarta, Indonesia


Mike Sheppard Cambridge, England


Sanjaya Sood Houston, Texas


Oilfield Review Winter 2009/2010: 21, no. 4. Copyright © 2010 Schlumberger.


For help in preparation of this article, thanks to Mo Cordes, Houston; and Stephen Hallinan, Milan, Italy.


GeoFrame and TerraTek are marks of Schlumberger.


1. Blodgett L and Slack K (eds): Geothermal 101: Basics of Geothermal Energy Production and Use. Washington, DC: Geothermal Energy Association (2009), http://www. geo-energy.org/publications/reports/Geo101_Final_ Feb_15.pdf (accessed August 1, 2009).


138 14,000 1,390 530 9,000


> Potential hydrothermal resources. The first major hydrothermal developments were located in areas with high tectonic activity marked by volcanoes, geysers, hot springs and large hot-water reservoirs. These resources are relatively shallow and often flow to the surface naturally. A large portion of potential resources, given here in megawatts, is made up of enhanced geothermal systems (EGS) and is contingent on technological development.


38,000 923 10,000 2,850 30,000 100,000 3,291 42,000


The mechanics of harvesting the Earth’s natural subsurface heat seem to be familiar petroleum engineering tasks: drill and complete wells and produce fluids from wells landed in targeted for- mations beneath the surface. But the prize in geothermal energy production is not fluids. It is heat. So while there is considerable potential for technology transfer from the oil and gas upstream business—drilling rigs, bits, pressure control and other basic practices and technologies—the specifics of hydrocarbon and geothermal energy production diverge. For example, ultrahigh temperature repre-


sents an obvious problem in bringing oil industry technology to bear on geothermal exploration and production: It renders useless the sophisticated tools and sensors that are dependent on pressure- tight seals and electronics. The industry, however,


Potential hydrothermal resources Installed hydrothermal capacity


is continually overcoming temperature limita- tions. In reality, the accurate characterization of geothermal reservoirs is a more fundamental obstacle to realizing the full energy potential from the Earth’s heat. Constructing geothermal reser- voir models and simulations using seismic surveys and logging data will require more innovation than adaptation such as increases in hardware temper- ature tolerances. Still, the comparison between heat and hydrocarbon exploitation remains compelling. Many of the geothermal wells currently feeding power plants have been constructed by oilfield workers using essentially traditional drilling and completion equipment and techniques. Today, those efforts have resulted in geothermal or, more accurately, hydrothermal fields that feed power plants producing about 10,000 megawatts (MW) of electricity in 24 countries (below).1


Potential hydrothermal capacity Potential capacity using EGS in the USA alone


392 5,800


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