The Iceland Deep Drilling Project (IDDP) is a groundbreaking research and development project aiming to exploit the heat found thousands of metres underground in volcanic bedrock. Backed by the National Energy Authority of Iceland, Reykjavik Energy, National Power Company and HS Energy, the project offers the potential to drastically increase the amount of energy that can be harnessed through geothermal power plants.
Here, IDDP project coordinator and manager Gudmundur Ómar Friðleifsson explains how a series of fortunate accidents and bold decisions led to a world record steam temperature and the creation of the first ever magma enhanced geothermal system.
Adam Leach (AL): At what point in the project did you realise you had drilled into a magmatic zone?
GudmundurÓmarFriðleifsson (GOF): It was certainly unexpected. In the field that we were drilling, we could expect (based on seismic data obtained in 1977 during a volcanic episode that started in 1975 and finished in 1984) magma at roughly 3km depth.
We were aware that we might possibly find magma earlier, but when we started drilling we came across conditions we didn't expect, even though we had drilled deeper before and drilled to the same depths just 100m away from it. After a series of problems, which was unusual in the sense that we were drilling much wider diameter drill holes than we were used to in conventional drilling, we didn't know we were drilling into magma until we got some return to the surface. The reason for this was a total loss of circulation, so we didn't get any return of water or cuttings to the surface. It's sometimes called blind drilling.
So we were drilling blind into the zone and then all of a sudden we got a kick, where the drill string weight decreased. The last time we drilled into it, determined to deal with it and continue, we set a casing down to 1,950m and cemented it into the formation. So we drilled into it and instead of trying to escape it, just stayed still.
AL: How did you respond, once you realised that you had drilled into a magma centre?
GOF: Once we realised we had drilled into a magma centre, we evaluated the situation and asked,'Can we drill through the magma?' 'Is it a small pocket or a dyke that we can drill through and continue?' We did some calculations on how thick it needed to be to stay magma from 1984 when the volcanic episode was completed. We calculated that it must have been a 50 to 100m intrusion to be able to stay magmatic all this time, because magma normally tends to cool.
Once we knew, we decided we couldn't continue drilling, because there were simply a number of problems, but instead of cementing the well with a plug, we decided, because we were prepared for it, to put a sacrificial casing into the production casing all the way down to the bottom of the well with perforations down the last 100m.
AL: How did you establish and test the well once you decided to proceed?
GOF: We did some exercises on cementing the casing with ballast down to 1900m inside the other casing, which was quite an exercise but a successful one. After that, we cooled the well for a month or two with all the water we had, at a rate of something like 50-60 litres per second, and then closed the well and waited for its recovery, for more than half a year until we had sufficient pressure and temperature to start flow testing the well.
After a few days of flow testing we found out it was too narrow and the superheated properties of the steam created very corrosive conditions. That delay caused us to take up the diameter of the flow line system on the surface up to 10 inches. We then flow tested it for two years, to see that it was capable of producing power up to something like 35-36MW fully opened. The hottest steam we got was 452°C, which is a world record for a production well.
AL: What is the process to turn the steam from the well into energy at the nearby power plant?
GOF: It was way above the pressure that their turbines were dealing with, so in order to take it into the existing power plant, we needed to depressurize it and clean the elements that were not favourable for the turbines. There were mostly three elements, non-condensable gases like sulphur, a little bit of CO2, so little that we could almost get carbon credit for it, and chlorine, not that high but sufficiently high enough to cause corrosion upon condensation. We also found particles of silicon, nearly industrial grade silicon with hardly any impurities, which over a year would be two or three truck loads which would be a piece of cake to get rid of.
We had to clean all of this out, so over two years we carried out a lot of experiments on wet scrubbing, where you water the steam. When you do this, you lose some energy, but you get the elements like sulphur and the particles like silicon into the water. By doing this we could know the PH of the fluid and clean out the chlorine, sulphur and silicon and be left with pure steam, which we could take directly into the power plant.
AL: What caused the well to be taken out of operation?
GOF: We had an issue where one of the small valves in the superstructures of the flow line system on the surface started to leak and we had to close the master valves and then two master valves on top of the well head both failed. This was something we did not expect and it meant we had to quench the well with cold water. It is now in the condition where it needs to be kept cool. We need to replace the master valves and possibly repair the casing, but at the moment we haven't analysed it sufficiently to know if we can repair it or not.
AL: How did you come to realise that you had created the world's first magma-enhanced geothermal system?
The interesting thing about all this is that when we injected the cold fluid, after the two years of experiments, we put some tracer down and that tracer was detected in a neighbouring well that is producing from a depth of roughly 1400m in the conventional geothermal system. The significance of that means that the tracer from the IDDP well is going back into the conventional system, so the fluid from the conventional system can go down as well, into the magma chamber when we start flowing the well and create a low pressure regime. It simply means that we created, maybe accidentally, the first magma enhanced geothermal system, with heat sources of about 900°C.
AL: What is the next step in the programme?
GOF: The next step for the power company, almost inevitably, is either repair this well and continue production with it, or drill a similar well, case it down about 1800m and just start producing from the system. Then you are talking about several orders of magnitude higher production than from conventional systems. An average well is say 5MW; this one, even with scrubbing, will be over 20MW.
It would also be less problematic than dealing with similar fluid or mixtures from superheated steam into a liquid system because then you have acid corrosion from condensation of the steam. This would be simpler to deal with, but of course you are dealing with extreme temperatures. Although, these are temperatures that the nuclear and coal fired power plants are dealing with every day so that shouldn't give us a problem, it just needs the right handling.
AL: What other potential projects are possible in Iceland?
GOF: We're studying the heat sources in Miocene volcanoes, so volcanoes active five million years ago, and we have seen there is mineralogical evidence that there is both supercritical and superheated fluid. This is how this proceeds, we know this exists, but the question is, can we harvest it?Can we get into the situation where we can do something about it and exploit it? Those of us who are working on it at the minute, believe we can, but we need to continue and it's an expensive exercise.
AL: Are there similar projects in other countries?
GOF: New Zealanders have been participating in our exercise and US geologists are trying to promote it in the US. The Japanese want to drill into hot granite at over 500°C and hydrofrack it with cold water fluid and then retrieve it in shallower wells as conventional steam. Geologists from around the world are ready to deal with it, but of course there are a lot of conventional systems that are yet to be harvested.
AL: What excites you about the future of the IDDP project?
GOF: What we are doing and what we have already done is just a step towards the future. The interesting thing about the next place we are going to is that it has seawater salinity, whereas the systems that we have already tested are meteoric water centres. The Reykjanes system is seawater bed, and the seawater bed system is in most respects very similar, with black smoker systems on the ocean floors.
There are hundreds of black smoker systems on the ocean ridges, down the Atlantic and into the Pacific, so if we can master a technique to deal with them and the supercritical water they are expelling, there is a colossal amount of energy to he had. It's really scientific imagination, but it's not necessarily so far in the future.