Hydrothermal Spallation Drilling Technology: An Alternative Method of Geothermal Energy Development

摘要

Hydrothermal Spallation Drilling (HSD) is a relatively new method suitable for drilling through hard and brittle rocks usually encountered in deep wells and more commonly in geothermal well drilling. Up to 70% of the cost of a geothermal energy project is spent on drilling since today almost all deep wells are drilled by conventional rotary drilling. Among all sustainable energy sources geothermal energy has an advantage of its energy production being independent of climatic conditions, however to allow installation of geothermal power plants geothermal wells have to be drilled at low costs. Conventional rotary drilling in hard formation is expensive because of bit wear which causes more tripping during drilling and hence increases the cost. Therefore, HSD comes in to save the cost of drilling by up to 15-20%. This document reviews the technology, its mechanism, status and future. With the global increment in the contribution of geothermal energy expected in the future, 5% of global energy by 2050, HSD is a game changing technology to increase the profitability and competitiveness of geothermal energy in relation with other sources of energy. However, just like any other technology HSD has shortfalls which are discussed in this document. These shortfalls have set a trend in the research world which has been mainly conducted in Switzerland and US. Overall assessment of the technology is promising and it will work to supplement conventional rotary drilling rather than replace it.