A system for producing working fluid and generating thermal or electrical power from a geothermal reservoir containing steam, the system comprising: an outer production conduit comprised of a lined well or hole open to the reservoir; a heat exchanger disposed within the outer production conduit, the heat exchanger comprising an outer heat exchange conduit and an inner heat exchange conduit; a working fluid circulation system for circulating a working fluid (a) through the outer heat exchange conduit and into the inner heat exchange conduit or (b) through the inner heat exchange conduit and into the outer heat exchange conduit; and an energy utilization or conversion system for using or converting energy contained in the heated working fluid recovered from the heat exchanger at the surface for thermal or electrical power; characterised in that the system further comprises a measurement and control system for controlling the rate of flow of the working fluid in the heat exchanger configured to result in steam condensing into water at the surface of the outer heat exchange conduit causing a significant density difference resulting in the condensed steam flowing deeper into the reservoir causing steam to flow from deeper in the geothermal resource towards the conduit adding advection heating to the conduction heating; a system of one or more plugs or other barriers disposed in the annulus between the well and the outer heat exchange conduit configured to prevent steam from rising up the annulus around the outer heat exchange conduit rather than condensing into water at the surface of the outer heat exchange conduit below the one or more plugs or barriers. an outer production conduit comprised of a lined well or hole open to the reservoir; a heat exchanger disposed within the outer production conduit, the heat exchanger comprising an outer heat exchange conduit and an inner heat exchange conduit; a working fluid circulation system for circulating a working fluid (a) through the outer heat exchange conduit and into the inner heat exchange conduit or (b) through the inner heat exchange conduit and into the outer heat exchange conduit; and an energy utilization or conversion system for using or converting energy contained in the heated working fluid recovered from the heat exchanger at the surface for thermal or electrical power; characterised in that the system further comprises a measurement and control system for controlling the rate of flow of the working fluid in the heat exchanger configured to result in steam condensing into water at the surface of the outer heat exchange conduit causing a significant density difference resulting in the condensed steam flowing deeper into the reservoir causing steam to flow from deeper in the geothermal resource towards the conduit adding advection heating to the conduction heating; a system of one or more plugs or other barriers disposed in the annulus between the well and the outer heat exchange conduit configured to prevent steam from rising up the annulus around the outer heat exchange conduit rather than condensing into water at the surface of the outer heat exchange conduit below the one or more plugs or barriers. a measurement and control system for controlling the rate of flow of the working fluid in the heat exchanger configured to result in steam condensing into water at the surface of the outer heat exchange conduit causing a significant density difference resulting in the condensed steam flowing deeper into the reservoir causing steam to flow from deeper in the geothermal resource towards the conduit adding advection heating to the conduction heating; a system of one or more plugs or other barriers disposed in the annulus between the well and the outer heat exchange conduit configured to prevent steam from rising up the annulus around the outer heat exchange conduit rather than condensing into water at the surface of the outer heat exchange conduit below the one or more plugs or barriers.