The DESCRAMBLE project reached its scope with several important achievements. Supercritical conditions were reached at 2,7-2,9 km depth, with measured temperature up to 507-517°C and an inferred pressure from Leak off Test of 300 bar. Unfortunately no commercial fluid has been identified. Due to the unexpected and above design conditions (450°C max) it has been decided do not further penetrate into the seismic reflector down to 3.1 km, where an extrapolated temperature of 600° could be expected, corresponding to the molten phase of granite, resulting in too dangerous conditions for a further deepening of the well.
On the other hand, from the dynamic modelling it is likely that the system we have discovered is in a thermal transient mode, from a very recent magmatic intrusion event lasting 50,000-100,000 year ago.
From all the new knowledge acquired by DESCRAMBLE, a new interpretation of the meaning of the seismic signal (K-horizon) will be achieved and further elaboration will bring more light on such a complex structure.
It is very important to highlight the following major results:
• Drilling: The drilling team gained an extraordinary experience in how to handle very extreme temperature conditions, and the problem derived as a consequences of the high temperature (cementing failure, mud behaviour) have been faced and solved. The experience on special equipments from oil & gas technology and never used in a geothermal well, is a valuable piece of knowledge, which will push upwards the possibility of further high temperature and pressure well drilling in the near future.
• The development of a first-of-a-kind temperature/pressure logging tool: A new high temperature and pressure (up to 450°C, 450 bar) logging tool, has been designed, built and preliminarily tested. the SINTEF tool has been then utilized up to its design limit, with an excellent performance and achieving quality results.
• Data integration and characterization: Several important information have been collected before and during drilling phase: well log data, cores from this well and nearby ones, fluid samples, geophysical data (VSP, piggy back seismic acquisition). The effort of integration and interpretation was challenging, but finally and an excellent reconstruction of the deep drilling target was obtained.
• Modelling: several different models have been realized by the two modelling groups, and their major results are in quite a good agreement with the measured data from the well. Regional and local 3D geological and thermodynamic models have been built, tested and continuously updated with the latest information. Rock and fluid sample were collected for laboratory analysis, which is providing further insight of deep geological, geochemical and geophysical condition.
