Technology Intersection between Geothermal and Oil & Gas Cultures Part 1

by Olli Coker

I attended the recent New Zealand Geothermal Workshop and came away with a lot of learnings.  A few of them really impressed me, so I would like to share some eye-openers that are examples of technology intersections.

Geothermal wells are currently being drilled with as large a flow diameter as can be economically justified.  And … the rocks are extremely hard, temperatures high, relatively shallow (compared to O&G wells) and of course the rock is fractured and circulation loss is common.  This makes for very difficult drilling; large hole sizes are just part of the problems.  O&G bits available are more suited to sedimentary formations than the high strength metamorphic and igneous rocks, especially in very non-uniform fractured environments.  In an unusual (but which I fervently hope will grow to be common-place) cross pollination between the O&G culture and the Geothermal culture, a bit vendor is offering built-to-order bits.  This is not unheard of in the O&G business, but most operators have opted for off-the-shelf bits, or at least follow-on orders of a custom bit that worked well.   But making bespoke bits routine? 

Below is Contact Drilling’s non-standard bespoke 20.75” bit that allowed the drilling rate of penetration to be roughly doubled while having a longer life, resulting in a 25% savings in the multi-well drilling campaign when compared to drilling with the previous bit program. Take a look at all the options available from NOV/ReedHycalog! This is especially alluring to drillers both geo-mechanics and drilling mechanics background.

PDC’s in extremely hard rock?  With high RoP? Really?  Yes, it’s a reality – for as much as the freedom-to-choose with bespoke bits is a great step forward, so much research has now been accomplished in a short time that tough, properly shaped and placed PDC’s have become the choice for breaking this extreme rock.

Of course, the authors note that the mixing of the two cultures is only possible with close (or closer) cooperation between operator and bit vendor.  Impressive, to say the least.  This one is a great example of the fusion of the two cultures.  Kudos to those involved:  Ellie Lock (Contact Energy) and Pawl Vistor (NOV/ReedHycalog) and to the organizers of the NZGW2020 – an excellent conference that I recommend.