A method for producing mechanical energy from geothermal fluids in which a heat transfer fluid (HTF) is heated by direct contact with the hot geothermal fluids, thereby partially cooling the geothermal fluids. A working fluid is heated by direct contact with the partially cooled geothermal fluid and is heated further by indirect heat exchange with the hot HTF. The heated working fluid is utilized in a heat engine for the production of mechanical energy.

There is disclosed a method for recovering energy from subterranean geothermal brines and increasing geothermal well production. The method comprises establishing a column of brine in a well casing having a tubing therein, open at its lower end to the column of brine and injecting a high pressure vapor such as nitrogen or steam into the bottom of the tubing in sufficient quantities to form a mixture of brine and vapor having a substantially lesser density than the surrounding column of brine whereby the hydrostatic head of the column of brine lifts the mixture to the surface. The mixture is withdrawn from the well and passed to a vapor-liquid separator where the vapor portion is separated without effecting any significant reduction in pressure of the produced mixture, whereby the pressure is maintained on the brine in the well at a sufficient value to prevent carbonate and scale formation. In the preferred embodiment, the separated vapor is divided into two portions, one portion goes to production and is used to produce energy or as a high temperature heat source. The other portion is repressured and injected into the well as the source of high pressure vapor used therein. The brine separated from the vapor is depressured and the evolved vapor is expanded to produce useful work in a plurality of states. In a preferred embodiment using steam, the vapor is separated by contact of the vapor with brine from a succeeding brine depressurization step, condensing that portion of the vapor intended for subsequent power generation.

Highly saline geothermal brine, such as that produced from the lower geothermal reserve of the Salton Sea geothermal field, is diluted with non-geothermal water of much lower salinity in a mixing zone proximate the high temperature end of a geothermal power plant, and preferably down in the production well just above the production zone, so as to reduce the chloride salt content of the production brine to a level that is at or below the saturated level at reinjection temperatures, thereby preventing any material chloride salt scaling at any location in the plant through reinjection. The permanent cemented-in production casing in the well is protected against the corrosive effects of the hot production brine by means of a removable production liner that is generally coextensive with the casing. Said mixing zone is provided in the lower portion of the liner, and the liner establishes an annulus between it and the casing through which said non-geothermal water flows downwardly to the mixing zone so as to exclude the production brine from contact with the casing.

A process for treating and deriving useful energy from a two-phase geothermal brine containing non-condensible gases, including hydrogen sulfide, and also containing heavy and/or transition metals in solution, wherein the non-condensible gases are separated from the geothermal brine. Substantially all of the hydrogen sulfide contained in the non-condensible gas is converted to sulfur dioxide and at least a portion of the sulfur dioxide is removed from the non-condensible gas thereby rendering the same environmentally acceptable for discharge. The separated geothermal brine is flashed to a high quality steam utilized for energy derivation. The portion of sulfur dioxide removed from the non-condensible gas is added to the remaining brine for reinjection into the subterranean geothermal reservoir.

A flashing apparatus for a geothermal power plant in which underground hot water introduced into the flashing apparatus is flashed therein to generate flashed steam is divided into a flashing chamber, a water separation chamber, a drain discharge chamber, and a steam discharge chamber by several vertical and horizontal perforated partition plates and the generated steam is fed into a steam turbine through these chambers and partition plates. The flashing apparatus comprises a horizontal cylindrical container closed at both ends by end plates one of which has a hemi-spherical configuration on which the underground hot water is ejected and a drain catcher is located in the flashing chamber to catch and remove drain.