How to choose a geothermal consultant for a deep geothermal project

You have a licence area, a buyer for the heat or power, and a budget decided mostly by a handful of deep wells. Now you need a geothermal consultant, and a search for geothermal consulting firms returns heat pump designers, building services engineers, large engineering houses and subsurface specialists under the same word. They are not interchangeable. This note is for the developer who has to choose one, write the scope and defend the choice to a board or a lender.

What separates a deep geothermal consultant from a shallow one?

Shallow geothermal means boreholes a few hundred metres deep at most, a loop of pipe and a heat pump that lifts low-grade heat for a building or a local network. Small rigs do the drilling, the design sits close to building services, and permits are usually local. It is real engineering, but a different job.

Deep geothermal means wells drilled kilometres into rock known mostly from seismic surveys, producing hot, pressurised water that must be brought up and put back for decades. Rig time is paid by the day, the wells are typically the biggest cost in the project, and approval sits with a regulator rather than a planning desk. Few of the skills carry over from shallow work, so the first filter on your shortlist is simple: have the people on this team designed, drilled or reviewed wells at the depth and temperature you are planning?

Why oil and gas well experience matters when you hire

The people who have designed and supervised wells kilometres deep mostly learned the trade in oil and gas. The rigs, casing, cement, pressure control and contractors are largely the same, and so are the ways a well goes wrong.

What you are paying for is judgement in three places. At the design review, someone has to spot the steps in the drilling plan most likely to cost extra rig days. At the contract, someone has to write down who pays when the hole misbehaves. At the rig, someone has to make the calls that move your budget, often at night. A team that has done those jobs to standards such as NORSOK, ISO and API brings that judgement with it. When you compare geothermal drilling and well engineering services, look for that record in the named people, not the company profile.

Oil and gas experience is not the whole answer, because a hot-water well lives with heat, temperature swings and corrosive brine for its whole working life. A good deep geothermal consultancy keeps the oilfield discipline and changes the design basis. Ask any bidder where they would depart from a hydrocarbon standard, and why. A firm with no answer has not yet made the translation.

The subsurface and the regulator, in plain words

The subsurface question is what lies down there: how hot the rock is, how easily water moves through it, and where the faults are. Nobody knows for certain before the first well. A useful consultant separates what has been measured from what has been assumed, shows what each assumption does to the well count and the budget, and flags any fault close enough to raise the risk of tremors felt at the surface. That is the core of geothermal resource and subsurface evaluation, and it should read clearly to the non-geologists on your board.

The regulator question is who has to say yes and what they need to see first. We provide independent geological assurance on a deep geothermal project in Switzerland, in support of the cantonal authorities, so we know what an authority looks for from its side of the table as well as the owner's. Good geothermal permitting and regulatory support starts before the well design is frozen, and our note on preparing for the regulator explains why.

What to put in the scope before you ask for proposals

A vague RFP returns proposals you cannot compare. Before you send one, write down seven things:

• The stage and the next decision. Well siting, contractor selection, a regulator submission or FID. Build the work around it.
• Review or ownership. Say whether you want a second opinion on someone else's well design, or a team that writes the design and defends it.
• Presence at the rig. Desk reviews and rig-site supervision are different services. If you want someone on your side on site while drilling, say so and ask who.
• Named people and their time. Ask for the individuals who will do the work and how much of their time the proposal assumes.
• Independence. Ask bidders to declare any commercial ties to drilling contractors, rig owners or service companies you may hire.
• What you will receive. Name the outputs and the decision each one serves: a well design review, a risk register, a drilling programme you can hand to contractors, a regulator submission. Say who on your side signs each one off.
• The data you hold. Seismic, records from nearby wells, earlier studies. Gaps here reshape the work.

What drives cost is the number of wells, the stage, how much reliable data exists, whether rig-site supervision is included, and how many rounds of questions the authority is likely to ask. When two bids are far apart, the gap usually sits in one of those assumptions, so ask every bidder to state them, and to say how the price is built: fixed or time-based, what is excluded, and what would trigger a change. A low bid that leaves rig-site time or regulator questions outside the price is not a low bid.

Questions to ask a geothermal consultant before you sign

• Which deep wells have the people on this proposal designed, drilled or reviewed, and in what role?
• Who will do the work day to day, and will the person who scoped it stay on it to the end?
• How will subsurface uncertainty be shown to you, and how does it feed into the well count and the budget?
• Which regulator has the team faced on a comparable project, and what did it ask for that the developer did not expect?
• What would lead the team to advise against drilling, or to change the plan?
• Is there a redacted example of a well design review or a regulator submission you can read?
• Can the firm put you in touch with a past client, ideally a developer or operator who used the same people on deep wells?

Hire the people, not the logo. A consultancy is only as deep as the team that will sit in your design reviews and pick up the phone when the rig has a problem.

Red flags when comparing geothermal consulting firms

• References that are all heat pump or shallow projects, however many there are.
• A senior name on the cover with no senior time in the plan.
• Confident resource numbers with no range around them before a single well is drilled.
• A hydrocarbon standard applied unchanged to a hot-water well.
• Regulatory work shown as a report at the end.
• Any tie to the contractor you are about to hire. An owner-side consultant should answer only to you.

For an example of the record to ask for, see our anonymised engagement Deep geothermal wells, delivered to standard.

Since 2015 we have worked as owner's engineer across oil and gas, geothermal and CO2 geological storage, so the oilfield discipline this note argues for is the one we bring to geothermal wells. If you are drafting the scope or weighing bids for deep geothermal wells, tell us where the project stands. The partner who scopes the work stays on it to the end, so the name on our proposal is the person in your design reviews.