Process for recovery of energy from geothermal fluids such as geothermal brine in a geothermal formation by injecting a water immiscible working fluid, preferably organic, typically a hydrocarbon, e.g. isobutane, into the geothermal formation containing a geothermal fluid such as hot brine, wherein the hydrocarbon working fluid is heated by direct heat exchange contact with the hot geothermal fluid in the formation, and employing the hot working fluid to drive a heat engine or turbine to produce work or electrical energy or to provide heat energy to a chemical process (e.g., alcohol manufacture). The cooled working fluid discharged from the turbine is reinjected into the geothermal formation. The working fluid preferably has a density which changes substantially with temperature to provide a substantial pressure difference for causing flow of heated working fluid up the production well. The density difference can be due to phase transfer from liquid to gas.
BACKGROUND OF THE INVENTION
This application is a continuation-in-part of application Ser. No. 875,139, filed Feb. 6, 1978, now abandoned, the entire disclosure of which is incorporated herein by reference.
A geothermal power plant operating on high pressure geothermal fluid includes a primary separator for separating the geothermal fluid into two channels, one containing high pressure steam and the other containing high pressure liquid. A primary steam turbine in the high pressure steam channel is responsive to high pressure steam for generating electricity and producing heat depleted high pressure steam. A secondary separator separates the heat depleted high pressure steam into a steam component and a liquid component. A primary heat exchanger is responsive to the high pressure liquid and the steam component for transferring heat to said steam component thereby producing low pressure steam and cooled high pressure liquid. At least one power plant module includes a low pressure steam turbine responsive to the low pressure steam for producing electricity and heat depleted low pressure steam; a condenser/vaporizer containing an organic fluid for receiving the heat depleted low pressure steam and converting it into condensate, and for vaporizing the organic fluid; an organic vapor turbine responsive to vaporized organic fluid produced by the condenser/vaporizer for generating electricity and for producing heat depleted organic fluid; a condenser for condensing the heat depleted organic vapor into a liquid; a preheater for heating the liquid; a pump for returning heated liquid from the preheater to the condenser/vaporizer; and a conduit for directing condensate from the condenser to the preheater.
A method for capping an idle geothermal steam well so as to prevent hydrogen sulfide emissions and well damage due to steam condensation includes replacing geothermal steam in a well borehole with gas, perferably an inert gas such as nitrogen, and sealing the well at the wellhead. Thereafter additional quantities of the gas are bled into the well borehole at a rate that substantially prevents steam condensation in the borehole. The method includes purging the well bore with air sufficiently to assure all steam is swept out of the well before the gas is introduced.
A method is provided whereby continuous injection of lift gas into a producing geothermal well, preferably from a liquid-dominated reservoir, increases production flow of geothermal fluids from the well by initiating a steam distillation effect within the wellbore. Apparatus is also provided for continuously injecting the lift gas during production from the well.
There has been invented a method for producing geothermal energy using supercritical fluids for creation of the underground reservoir, production of the geothermal energy, and for heat transport. Underground reservoirs are created by pumping a supercritical fluid such as carbon dioxide into a formation to fracture the rock. Once the reservoir is formed, the same supercritical fluid is allowed to heat up and expand, then is pumped out of the reservoir to transfer the heat to a surface power generating plant or other application.
A method of extracting thermal energy, in a cyclic manner, from geologic strata which may be termed hot dry rock. A reservoir comprised of hot fractured rock is established and water or other liquid is passed through the reservoir. The water is heated by the hot rock, recovered from the reservoir, cooled by extraction of heat by means of heat exchange apparatus on the surface, and then re-injected into the reservoir to be heated again. Water is added to the reservoir by means of an injection well and recovered from the reservoir by means of a production well. Water is continuously provided to the reservoir and continuously withdrawn from the reservoir at two different flow rates, a base rate and a peak rate. Increasing water flow from the base rate to the peak rate is accomplished by rapidly decreasing backpressure at the outlet of the production well in order to meet periodic needs for amounts of thermal energy greater than a baseload amount, such as to generate additional electric power to meet peak demands. The rate of flow of water provided to the hot dry rock reservoir is maintained at a value effective to prevent depletion of the liquid inventory of the reservoir.
