Identification of geothermal water-bearing formations after geo-data analysis and interpretation

The SEG Field Camp 2021 is planned to be performed in the northern part of Romania, in the Maramures area. Detailed geological and geophysical investigations will be performed in the Miresu Mare-Satulung-Sacalaseni area.

The scientific objectives of the field camp are to document the subsurface geological structure by collecting, processing, and analysing seismic reflection, ambient seismic noise, magnetic and magnetotelluric data and to identify water-bearing formations in the study area.

The main goal of the SEG Field Camp 2021 is to train undergraduate students on how to use geological and geophysical investigations in order to obtain information about the subsurface geological structure and to identify thermal water-bearing formations. Professors from the University of Bucharest in collaboration with senior researchers from PROSPECTIUNI S.A. and ICS Business International S.R.L. will be involved in the pre-field (training sessions), field (data acquisition), and post-field (data processing and interpretation) activities performed by students.

The study area is known to have the highest values of heat flow in Romania. Geothermal measurements performed in previous studies showed a geothermal gradient of 4.5-5.5 oC and temperatures higher than 140oC at depths greater than 3 km. Regional gravity and magnetic measurements were performed in this area more than 30 years ago. Seismic reflection surveys were not designed because the area was not considered of interest for hydrocarbon exploration. The geological section available for the southern part of our study area shows the presence of thin sedimentary formations, less than 200 m in thickness, which is in contradiction with the results of gravity data interpretation. Exploration wells were not drilled in this area. The information used to build the geological sections and maps was based mainly on surface geological mappings.

Recording and processing of seismic reflection data using explosive sources will help us to image with accuracy the thickness of the sedimentary formations and the locations of possible faults and/or fault systems. Shallow seismic reflection measurements using impact sources will be performed in the vicinity of villages (buildings) and along profiles located on the eastern part of the study area, where the sedimentary formations are interpreted to have thicknesses of a few tens of meters. Over the shallow seismic reflection profiles, we will perform Time Domain Electromagnetic Surveys (TDEM) using an equipment pack from AGCOS (battery-powered 250W transmitter and 100 000 – 500 Hz airloop sensor). The seismic reflection and resistivity surveys will be jointly processed and interpreted, in order to obtain optimum results in revealing the underground tectonics and lithology. Results of seismic reflection, ambient seismic noise, and magnetotelluric data processing will be jointly interpreted in order to identify water-bearing formations. Magnetic data processing will help us identify possible subsurface igneous bodies.

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