Tapping Into Geothermal a Hot Idea

The last 10 years has witnessed an expansion by the oil and gas industry in the type of energy resources that are being developed. Coalbed methane, gas shales, oil sand, oil shale and tight gas sands all have seen growth in numerous places worldwide as companies look for dwindling reserves to maintain operations and societal demand for greater amounts of energy production.

There is, however, another resource hidden within the depths along with oil and gas that has yet to be produced by the oil and gas industry: geothermal energy.

When geothermal energy is mentioned, the first location that many people think of is volcanoes, hot springs, fumaroles, etc., which are valid considering the nature of a volcano and the associated hot water with their formation at depth.

Most people in the O&G industry, however, know of stories where a drilled well encountered such high temperatures that “the tool melted in the hole.” These anecdotes have made for interesting stories, but they also represent the realization the industry quite often reaches temperatures in excess of 200 degrees Fahrenheit in its drilling for oil and gas.

Since heat is energy, the industry needs to realize it has left an untapped energy resource in the ground that has been considered a nuisance and a problem in the search for hydrocarbons, an energy resource that renews itself.

The question then arises: Would this energy be economic to develop?

Image of the AAPG 1972 geothermal database from O&G wells superimposed on a map of geopressured regions (in red) identifed in basins within the United States. The geopressured map is from Wallace, 1982 and the AAPG map is recreated by Blackwell and Richards, 2004.
Image of the AAPG 1972 geothermal database from O&G wells superimposed on a map of geopressured regions (in red) identifed in basins within the United States. The geopressured map is from Wallace, 1982 and the AAPG map is recreated by Blackwell and Richards, 2004.

Several companies already have begun to recognize this “stranded” heat energy resource and are beginning to harness this energy for electrical power generation in operations use.

For example:

♦ Continental Resources was approached by the University of North Dakota and Berrendo Wind/Geothermal with the idea of generating electrical power from several of their water wells.

Continental produces between 40,000 to 50,000 barrels of 190-200 F water per day from six water supply wells. As the water must be cooled prior to its use, Continental saw this as an opportunity to extract energy for electrical power generation and use within the Cedar Creek field, as reported in a 2009 talk at Southern Methodist University.

According to Berrendo, the organizations are working through the contracts with the U.S. Department of Energy (DOE), which is providing project funding, the university and Continental Resources.

♦ Denbury Resources is working in conjunction with Gulf Coast Green Energy, which acquired DOE funding, and Southern Methodist University to establish a co-production project at the Summerland Field in Mississippi. Produced water of nearly 200 F at 4,000 barrels per day will be used to offset electrical operating expense at this field, with the production of about 50 kilowatts of electricity. This is a test project to determine how effective co-production may be for offsetting these electrical expenses.

If successful, however, this may open the door for additional co-produced opportunities in geothermal energy development.

♦ Houston-based Hilcorp Energy is looking to supplement south Louisiana field operations by producing power from 240-plus F produced water in the 50-100 kilowatt range of output. They have one or more wells in the 4,000 to 5,000 barrels/day range that could help offset operating expense in the field.

Presently, Hilcorp is focusing on developing geothermal energy that is in conjunction with oil and gas production.

♦ Another company, Universal GeoPower, has focused on Texas as a region for establishing geothermal production, making use of the orphan well list available through the Texas Railroad Commission and, along with a DOE grant, pursuing possible sites in the Liberty County area.

They have created a flow model for reservoir analysis and have been developing the software by iteration, making predictions on past wells and comparing those with their actual production records and then making forward model predictions on new wells regarding fluid flow. As a result they have altered some of their strategy.

Universal is looking at sands of Eocene age where porosity can be 28-32 percent and permeability in the Darcy range.

Not every company is focusing on co-produced geothermal power in the oil patch.

♦ Pioneer Natural Resources is investigating the potential for developing geothermal power in the Raton Basin of Colorado.

This project, still in the early exploratory phase, is seen by Pioneer as an attractive alternative – or even a supplement – to existing fossil-fuel production due to geothermal energy’s potential as a long-term, clean and 24/7 base-load energy resource. This makes geothermal more attractive than other alternatives like solar and wind that have neither the 24/7 capability nor the issues surrounding operation and maintenance.

Pioneer has been working with the Colorado Geological Survey as this area is being investigated for its geothermal opportunity by other companies as well.

♦ Louisiana Geothermal, the sister company of Louisiana Tank, Jordan Oil and Central Crude of Lake Charles (La.), received DOE funding to conduct a geopressured geothermal project just east of the Sweet Lake area of Cameron Parish, keying off past DOE work in the Louisiana and Texas Gulf Coast.

The company anticipates this project to produce enough power in the next two years to provide much of the power needs of Cameron Parish.

The well will be drilled specifically for geopressured-geothermal power production to a depth on the order of 16,000 feet, with a calculated net potential of around 5.6 megawatts of power. Flow is anticipated at 30,000 barrels/day, with a capacity factor of 90-plus percent.

If all continues as planned, production could start as early as 2012.

This past July the DOE hosted a meeting of select professionals at the National Renewable Energy Laboratory in Golden, Colo., to discuss the low temperature (<400 degrees F) geothermal program for furthering its deployment nationwide.

Among the various suggestions made for developing this resource was the strong opinion that the expansion of low-temperature geothermal requires the inclusion of the oil and gas industry as a critical component. The oil and gas industry brings a large pool of talented geoscience and engineering professionals – and their respective companies – plus an understanding of subsurface energy production that would allow geothermal development in sedimentary basins, an unconventional arena for geothermal production and a bigger worldwide expansion of geothermal development.

Schlumberger’s recent acquisition of GeothermEx, a comprehensive geothermal consulting and services firm active in over 50 countries, suggests an increasing interest in geothermal energy as a future area of operations expansion – a potential now under consideration by oil and gas exploration and production companies in many favorable areas of the world.

Geothermal energy is once again poised for expansion worldwide. Because of its high 90-plus percent capacity factor, it has high continuous availability and is thus not susceptible to the volatility of oil and gas pricing.

Generation of electricity from geothermal energy would provide a steady, dependable cash flow that would support an O&G company to define the equivalent of a ‘baseload’ profit stream, just as the utility industry must always maintain a ‘baseload’ flow of electrical power that is available on demand.

Geothermal energy is the original renewable energy resource.

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Division Column-EMD Andrea Reynolds

Andrea A. Reynolds, P.G. EMD President 2012-13.

Division Column-EMD Richard Erdlac

Richard Erdlac, principal geologist with Erdlac Energy Consulting, Midland, Texas, is acting chair and vice chair-Industry of the EMD Geothermal Energy Committee.

Division Column-EMD

The Energy Minerals Division (EMD), a division of AAPG, is dedicated to addressing the special concerns of energy resource geologists working with energy resources other than conventional oil and gas, providing a vehicle to keep abreast of the latest developments in the geosciences and associated technology. EMD works in concert with the Division of Environmental Geosciences to serve energy resource and environmental geologists.

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The Energy Minerals Division (EMD), a division of AAPG, is dedicated to addressing the special concerns of energy resource geologists working with energy resources other than conventional oil and gas reservoirs, providing a vehicle to keep abreast of the latest developments in the geosciences and associated technology. EMD works in concert with the Division of Environmental Geoscientists (DEG), which serves environmental geologists working on projects associated with the oil & gas industry.

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Illite is not as well crystallized as expected for potential crystallization temperatures above 160°C measured by fluid-inclusion determinations. In both the northern and south-central North Sea, the two illite generations remain unaffected after crystallization despite continued burial, suggesting notably higher crystallization temperatures than those estimated from geothermal gradients. No recent illite crystallization or alteration is recorded in the K-Ar ages, despite a dramatic regional acceleration of the subsidence in the southern North Sea. ±

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