There have been considerable advances in high-temperature geothermal 
drilling technology and improving the output of wells over the past decade. The 
main interest is in technology that can lower the cost of geothermal wells both 
for exploration and production. This goal is a worthy one and at the present 
time two international efforts, ENGINE and IEA GIA, are under way to explore 
the possibilities. Actual well costs have, however, over the past few years not 
gone down, but increased rapidly mainly due to price increases and the cost of 
new technology. Drilling costs have also gone up because more challenging 
wells are being drilled going deeper and deviating from the vertical (“directional 
drilling”). The other way to lower the overall cost of geothermal development is 
to drill very productive wells. Considerable progress has been made in this 
respect. Once several wells have been drilled in the same geothermal field the 
results become more predictable and also how to deal with the drilling 
problems. Standardization of well designs and a more developed market for 
drilling services is likely to lower the cost. Contracts structured with incentives 
will also lead to greater efficiency. Nevertheless one must remember that 
geothermal wells are remarkably different, even inside the same field. The new 
technology adds to the costs but in balance it is hoped that the overall cost of 
geothermal development can come down in time and lead to more reproducible 
results. The ENGINE workshop 4 “Drilling cost effectiveness and feasibility of 
high-temperature drilling” in late June 2007 will explore these things further. 
Active participation from the ENGINE partners is thus sought.

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