WorldWide Drilling Resource

Will Drilling into a Volcano Blow the Top off Geothermal Power Production? Compiled by Bonnie Love, Editor, WorldWide Drilling Resource ® After more than 160 days, the Iceland Deep Drilling Project (IDDP) achieved a significant milestone. A team of geothermal researchers successfully drilled the world’s deepest well in an active volcanic area - the HS Orka geothermal field in Iceland, reaching a depth of more than 15,285 feet. Temperatures at the bottom of the well have already been measured at 800ºF (427°C). The DEEPEGS (deployment of deep enhanced geothermal systems for sustainable energy business) project is a four-year project led by HS Orka, in cooperation with other partners from Iceland, France, Germany, Italy, and Norway. The goal of the project is to test the viability of supercritical fluids for geothermal power production. Since the area beneath the production zone of the Reykjanes geothermal field had never been explored, it was selected as the test site for the scientific well IDDP-2. The IDDP - 2 well took advantage of one of HS Orka’s production wells and deepened the hole to about 9800 feet, where it became the well with the deepest casing in all of Iceland. From there, the well was deep- ened to its final depth of 15,285 feet from the rig floor. Should this well prove to be useful for ener- gy production, it could open the door for a new powerful source of geothermal power. The plan is to access extremely hot water which is under such extreme pressure it’s in a supercritical state, which has properties of both a gas and a liquid. The supercritical fluid has a much higher energy content than conventional high - temperature geothermal steam. If supercritical wells are able to produce more power than conventional geothermal wells, fewer wells would be needed to pro- duce the same amount of power. “We just have to see . . . whether we are able to tame this mon- ster,” said Hjalti Páll Ingólfsson, from the Geothermal Research Group in Iceland. “Supercritical conditions can increase the power output of a typical (geothermal) well by ten times. That's at least the theory, and our aim with doing this demonstration is to see if the theory is true.” There are plenty of risks associated with drilling into volcanic areas. “We can expect magma, which we actually did get in another well,” Ingólfsson added. In addition to magma, which the engineers need to avoid, volcanic rock contains many faults and cracks which can cause the drill to get stuck, slowing down the drilling process and increasing the difficulty. In fact, the drill did get stuck a few times on this project. To avoid magma chambers, researchers deployed sensitive land and sea sensors around existing wells, includ- ing the new well, to record the noises produced by movements in the earth's crust. Analysis of these signals provided information on the size and depth of water reservoirs deep underground, as well as the presence of magma chambers. The team turned the metal casings of the existing geothermal wells into huge electromagnets and measured changes in the magnetic fields to find fractures and fault lines deep in the rock. There was onemajor issue which was never resolved - the complete loss of circu- lation below depths of about 10,000 feet. No matter how many circulation materials were used, and despite multiple attempts to seal the loss zone with cement, no drill cuttings returned to the surface. The project has proved to be a valuable learning experience in that it demonstrated the possibility of drilling a long, deep well in a high-temperature geothermal field. The knowledge gained from this project can be used in future projects, making it possible to deepen other existing wells. The purpose of the IDDP - 2 project is research, and the drilling completion is only one phase. The next steps will be to do further test- ing and research on the well; and most importantly flow tests and fluid-handling experiments will be conducted within the next two years. Core sample 11 from the project shows a network of mineralized planar fractures. Photos courtesy of IDDP. The deepest coring runs in the IDDP-2 borehole were carried out through a 7-inch liner using a Baker Hughes 6-inch polycrys- talline diamond bit which cut a 2.625-inch-diameter core. 29 WorldWide Drilling Resource ® DECEMBER 2017