MOBILE GEOTHERMAL POWER PLANT

Electric Power Generation Using Geothermal Fluid

Coproduced from Oil and/or Gas Wells


Abstract:        

Chena Power, in collaboration with Quantum Resources Management, United Technologies Research Center (UTRC) and Pratt & Whitney Power Systems  (PWPS) will demonstrate that electric power can be generated from the geothermal heat co-produced when extracting oil and gas from the earth.  Energy can be extracted from low-temperature geothermal resource present in the water, oil, and gas.  This untapped resource can be developed in an economically attractive manner.  This summer, a mobile geothermal power plant installation will be installed and demonstrated at Quantum Resources’ Jay Oil Field, which covers 13 square miles of northwestern Florida and southern Alabama. 

 

Producing oil and gas wells are an underutilized source of geothermal energy.  Most wells produce 95% water and 5% oil and gas. One of the significant economic barriers to developing geothermal power is the cost of drilling wells that have predictable access to fluid temperatures high enough to generate electricity. Chena Hot Springs Resort, Quantum Resources Management, UTRC, and PWPS are proving that geothermal energy production can coexist alongside current oil development operations. 

 

Chena Hot Springs Resort and UTRC have previously demonstrated the feasibility of developing low temperature geothermal resources for energy production.   At Chena Hot Springs Resort, three organic rankine cycle (ORC) units are installed that have a gross capacity of producing 680 kW of electricity.  The electricity produced at Chena Hot Springs Resort represents the lowest temperature geothermal resource (165°F) developed for electricity production in the world.

 

Based on the success of this technology in Alaska, the PureCycle®*[1] Power System Model 280 is being used in the mobile power plant application used to demonstrate the potential of generating electricity from the heat of oil and gas wells.  The Model 280 operates with the ORC using a non flammable working fluid. This technology has also proven to be constant and reliable, producing electricity 95% of the time while at Chena Hot Springs Resort.

 

            The power plant is designed to be non-site specific and mobile so that electricity can be produced in one location and be operational for the majority of the oil wells in the world without the need for permits associated with building and ground work.  The dimensions of the ORC are designed for easy movement through all 50 states.  Oil and gas resources are also only extracted when they can be developed economically.  When a well is no longer producing economically, this mobile geothermal power plant can be relocated to another well.  This non-site-specific power plant is capable of providing its own cooling and is able to extract cooling water from the hot water coming from the well.  The power plant requires minimal on site work and can be installed in one hour from the time it is dropped off.

 

At Quantum’s Jay Florida Field, the estimated daily production capacity is 4,500 barrels of crude per day plus 5-7 million cubic feet of natural gas.  Furthermore, in addition to the above mentioned hydrocarbons, 120,000 barrels per day of approximately 200 °F water is extracted and re-injected into the field.  The temperatures we will be working with in the field are approximately 185-195°F.  Overall, hot water represents approximately 95% of the fluid stream that returns to the central processing facility.  This hot water represents an untapped energy resource.

 

In the initial demonstration system, it is estimated that a range of 100kW to 280 kW of electric power will be generated by the ORC power plant depending on ambient conditions.  The net power generated will be used to offset part of the electric load at the oil field.  While this initial demonstration unit will generate up to 280 kW, it is estimated that the total generation capacity available on the inflow stream is well in excess of 5MW.

 

The production well at Quantum generates in excess of 600 gpm of production fluid at 185-195°F consisting of 95% water and 5% oil. Currently, the production fluid is transported to the refinery by means of a pipeline.  The power plant will be connected via a hot tap to the pipeline to feed the production fluid through a three-phase separator to the evaporator of the Model 280.  The production fluid exits the evaporator 30°F cooler and is then fed back into the pipeline to be transported to the refinery.

 

The condenser on the Model 280 will be using water that will need to be generated and cooled on site because the location of the production well is not located near a source of water.  The water will be separated from the production fluid consisting of 95% water.  After the production fluid exits the evaporator there will be a 2 inch branch line that can take a portion of the production fluid to an oil/water separator.  The fluid to the oil/water separator will be cooled through piping with cooling fins to reduce the temperature.  After the fluid is cooled, the fluid will be fed into a 25 gpm oil/water separator.  The 20 gallons of water separated out will be added to replenish the water lost from the evaporative cooling, and the oil will be pumped back into the pipeline at 5 gpm.

 

In the Model 280, water is used to condense the refrigerant.  The water enters the condenser at 78°F and exits at 88°F in the worst conditions of 105°F ambient with a wet bulb of 78°F.  The water will be cooled using three evaporative cooling towers that are connected in a parallel sequence.  The water exiting the condenser to the cooling towers will be controlled by butterfly valves so that the use of each cooling tower can be controlled based on ambient conditions.  Each cooling tower has a 4000 gallon reservoir where the water will be gravity fed into an 1800 gpm variable speed drive pump which drives the water through the condenser and cooling towers.

 


[1] PureCycle® is a registered trademark of United Technologies Corporation