Final Report Summary - HITI (High-Temperature Instruments for supercritical geothermal reservoir characterization and exploitation)
The HITI project developed new geophysical and geochemical sensors and methods that can be used in evaluating deep geothermal wells up to supercritical conditions, that is of temperature above 374 degrees Celsius for pure water and pressure above 220 bar. Supercritical wells may provide a very efficient way to produce electricity through renewable sources exploitation; however, the harsh conditions within these wells rend them presently non-conventional. HITI aimed to explore supercritical wells and enhance production from them, thus the developed set of tools and methods were chosen to provide a basic set of data needed to describe supercritical reservoirs structure and dynamics including the evolution of the borehole conditions during exploitation. The produced instruments could tolerate high temperature and pressure within a highly corrosive environment.
The project included seven work packages (WPs), related to the following issues:
1. project management;
2. instrumental development needed to acquire data on well fluid properties, which are necessary to evaluate the energy potential of a supercritical reservoir;
3. understanding of the structure and dynamics of the geothermal reservoir to assess the sustainability of hot to supercritical fluid production;
4. monitoring parameters that may result to production difficulties in operating wells, such as increased temperatures and corrosiveness;
5. in-situ demonstration and evaluation of the developed instruments and methods;
6. establishment of the state of the art of technologies used for geochemical and geophysical measurements at temperatures as high as possible, and determination of prospective strategies and new concepts in order to develop tools able to perform such measurements at temperatures for which currently no such ability exists;
7. project dissemination activities.
The set of instruments and methods developed during the HITI project consisted of seven components:
1. a memory based production logging tool (multi-sensor), capable of measuring temperature, pressure flow rate and casing collar location at borehole temperatures up to 400 degrees Celsius.
2. a wireline sensor capable of measuring temperatures up to 320 degrees Celsius.
3. a surface read-out (SRO) resistivity tool to permit open hole formation evaluation and characterisation for temperatures up to 300 degrees Celsius.
4. a high temperature televiewer with casing inspection analysis and a gamma ray detector shown to perform at 300 degrees Celsius, which is ideal for borehole deformation description and casing inspection, as well as for fracture detection and geotechnical rock classification. This combined tool had a modular design, and the televiewer and gamma units could be operated separately.
5. a novel high temperature fibre optic cable to provide accurate temperature profiles with a high temporal and spatial resolution at temperatures approaching 300 degrees Celsius.
6. development of a new thermometric relationship for use up to 325 degrees Celsius for the high-temperature dilute geothermal waters and realisation of tracer tests using organic compounds for temperatures up to 350 degrees Celsius.
7. development of a cell to measure the electric conductivity of basalts under supercritical conditions, which can give important information regarding reservoir properties.
Currently existing sensors and instruments for performing borehole measurements often have operational limitations related to high pressure and temperatures, mainly due to the electronics that are associated to the sensors. However the HITI project employed promising technologies and resulted in proving that in-situ real time monitoring of water physical and chemical parameters under harsh conditions should be realistic within the following years.
The project included seven work packages (WPs), related to the following issues:
1. project management;
2. instrumental development needed to acquire data on well fluid properties, which are necessary to evaluate the energy potential of a supercritical reservoir;
3. understanding of the structure and dynamics of the geothermal reservoir to assess the sustainability of hot to supercritical fluid production;
4. monitoring parameters that may result to production difficulties in operating wells, such as increased temperatures and corrosiveness;
5. in-situ demonstration and evaluation of the developed instruments and methods;
6. establishment of the state of the art of technologies used for geochemical and geophysical measurements at temperatures as high as possible, and determination of prospective strategies and new concepts in order to develop tools able to perform such measurements at temperatures for which currently no such ability exists;
7. project dissemination activities.
The set of instruments and methods developed during the HITI project consisted of seven components:
1. a memory based production logging tool (multi-sensor), capable of measuring temperature, pressure flow rate and casing collar location at borehole temperatures up to 400 degrees Celsius.
2. a wireline sensor capable of measuring temperatures up to 320 degrees Celsius.
3. a surface read-out (SRO) resistivity tool to permit open hole formation evaluation and characterisation for temperatures up to 300 degrees Celsius.
4. a high temperature televiewer with casing inspection analysis and a gamma ray detector shown to perform at 300 degrees Celsius, which is ideal for borehole deformation description and casing inspection, as well as for fracture detection and geotechnical rock classification. This combined tool had a modular design, and the televiewer and gamma units could be operated separately.
5. a novel high temperature fibre optic cable to provide accurate temperature profiles with a high temporal and spatial resolution at temperatures approaching 300 degrees Celsius.
6. development of a new thermometric relationship for use up to 325 degrees Celsius for the high-temperature dilute geothermal waters and realisation of tracer tests using organic compounds for temperatures up to 350 degrees Celsius.
7. development of a cell to measure the electric conductivity of basalts under supercritical conditions, which can give important information regarding reservoir properties.
Currently existing sensors and instruments for performing borehole measurements often have operational limitations related to high pressure and temperatures, mainly due to the electronics that are associated to the sensors. However the HITI project employed promising technologies and resulted in proving that in-situ real time monitoring of water physical and chemical parameters under harsh conditions should be realistic within the following years.
