Design of a Co-Production System for Steam and Freshwater in Fractured Porous Media Geothermal Reservoirs

Abstract

Permeable fractures and fault zones mostly control the flow of water in volcanic systems. The need for freshwater for geothermal drilling operations and the attendant challenges in meeting its demand cannot be overemphasized. This paper proposes a one-stop shop solution for combined abstraction of geothermal fluids and groundwater from fractured reservoirs. Conventional well designs concentrate on the wellbore and the products therein which are basically geothermal fluids (steam and brine). This innovative co-production design attempts to increase the pay zones in a drilled well by allowing for the abstraction of freshwater for drilling, injection tests, cooling of geothermal power plants, dust suppression, cleaning, maintenance and direct use activities such as crop irrigation. This improves on geothermal well cost-benefits per drilled depth. The intermediate casing in a typical well is modified to accommodate a freshwater annular suction conduit that draws water from upper section to approximately 500m depth in the formation of a drilled geothermal well using a jet pump or multistage pump mounted on the surface. With further research the innovative technology can be employed in simultaneous abstraction of oil and gas in oil and/or gas reservoirs or a combination of both.