DOE successfully generates electricity from producing well's hot water

Electricity has been generated successfully from a producing oil well's geothermal hot water for the first time, the US Department of Energy's Fossil Fuel Office reported on Oct. 18.

Electricity has been generated successfully from a producing oil well's geothermal hot water for the first time, the US Department of Energy's Fossil Fuel Office reported on Oct. 18.

DOE's Rocky Mountain Oilfield Testing Center and Ormat Technologies Inc. of Reno, Nev., began a 12-month test in September at RMOTC's Naval Petroleum Reserve No. 3 site north of Casper, Wyo., DOE said. A standard commercial Ormat Organic Rankine Cycle power plant, using hot water from a producing oil to exchange heat in an Ormat Energy Converter, is being used, it indicated.

"This project is unique in its production of onsite renewable power and has the potential to increase the productivity and longevity of existing US oil fields. Harnessing hot water produced during production to power the oil field could lead to more economical access, especially in older, depleted fields," said James A. Slutz, DOE's acting assistant secretary for fossil energy.

A large number of US oil and gas fields produce hot water as well as hydrocarbons, he noted. Such wells, which typically produce fluids at temperatures below 220 degrees Fahrenheit, could be capable of generating more than 5,000 megawatts of electricity, he said.

In the current test, a binary power unit moves hot water from a producing well to a heat exchanger, where it vaporizes a secondary fluid with a lower boiling point, according to DOE. The secondary fluid's vapor then is used to turn a turbine coupled to a power generator. Electricity is then supplied to the field's electrical system, where it runs production equipment, it said.

150-200 gross kilowatts

DOE said that the generated electricity is metered and monitored for both reliability and quality. The test has been producing 150-200 gross kilowatts of power since it started in early September, it said.

It said that the cooled geothermal fluid from power production can be re-injected into the reservoir or discharged, depending on the location. Currently, the 190 degree F water produced from NRP-3's Tensleep sandstone formation is treated before being safely discharged into a stream nearby. The unit's energy converter captures the water's heat and uses it before the water is discharged.

DOE said that while the unit at NRR-3 is the first to use geothermal water from a producing oil field, it is similar to a 250 kw Ormat unit which has generated electricity at an Austrian resort from 210 degree F geothermal water for more than six years. Similar units have been in continuous operation in Nevada and Thailand since the 1980s and have been field-proven in 1,000 installations worldwide, it said.

Approximately 8,000 wells which produce both hot water and hydrocarbons have been identified in Texas alone, DOE said. Ormat is assessing the feasibility of using such wells to support onsite power generation by employing its sub-megawatt geothermal power units, it added.

Contact Nick Snow at nicks@pennwell.com

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