In the context of the Geothermal Technology Program at GFZ, the former gas exploration well Gros ... more In the context of the Geothermal Technology Program at GFZ, the former gas exploration well Gros Schonebeck 3/90 (50 km northeast of Berlin) was reopened and deepened to 4309 m depth. For the last 6 years, this well has served as a geothermal in-situ laboratory for in situ experiments and the development of stimulation concepts. The objective of these stimulation operations was to create secondary flow paths and to improve the inflow performance of the well. The well makes the deep sedimentary Rotliegend reservoir accessible, which is characterized by water bearing porous and fractured rocks. To complet e a potential doublet for power generation, the second well Gros Schonebeck 4/05 was drilled in late 2006. At pay -zone depth level the maximum distance between the two wells is approximately 500m. The most promising sandstone layers for stimulation were identified by measured porosity distribution, water saturation and calculated permeability data. This information is a prerequisite...
The Rotliegend of the North German basin is the target reservoir of an interdisciplinary investig... more The Rotliegend of the North German basin is the target reservoir of an interdisciplinary investigation program to develop a technology for the generation of geothermal electricity from low-enthalpy reservoirs. An in-situ downhole laboratory was established at the site of the deep well GrSk 3/90 at Gros Schonebeck with the purpose of developing appropriate stimulation methods to increase permeability of deep aquifers by enhancing or creating secondary porosity and flow paths. The goal is to learn how to enhance the inflow performance of a well from a variety of rock types in low permeable geothermal reservoirs. At present, a research borehole has been drilled to 4.3 km depth and is completed in sedimentary rock formations bearing 150°C. This well (GrSk 3/90), originally completed in 1990, was re-entered in 2000, hydraulically stimulated in 2002 and 2003, and tested in 2003, 2004 and 2005. In April 2006, drilling started on a second well to enhance mass-flow rate from the reservoir us...
Lower Permian siliciclastic sediments and volcanics are widespread strata throughout the Central ... more Lower Permian siliciclastic sediments and volcanics are widespread strata throughout the Central Europe forming deeply buried aquifers in the North German Basin with formation temperatures of up to 150°C. These on average 4000 m deep structures are investigated to develop stimulation methods to increase the permeability by enhancing or creating secondary porosity and flow paths. The final goal is to test the generation of geothermal electricity from such low-enthalpy reservoirs using a doublet of borehole, one to produce deep natural water and the other to re-inject the utilized water. For these purposes, an in-situ downhole laboratory was established in Gros Schonebeck, north of Berlin, Germany. At present, two 4.3 km deep boreholes have been drilled. The first well GrSk 3/90, originally completed in 1990 as a gas exploration well and abandoned due to non-productivity, was re-opened in 2000 and was hydraulically stimulated in several treatments between 2002 and 2005. In 2006, the second well GrSk 4/05, planned for extraction of thermal waters, was drilled in order to realize a doublet system with two hydraulically connected boreholes. It is planned to stimulate in the second well both, the Lower Permian sandstones and the underlying volcanic rock. The resulting engineered reservoir should have an increased productivity being operated with minimized auxiliary energy to drive the thermal water loop and should have a minimized risk of a temperature short circuit of the system during a planned 30-year utilization period. The forthcoming phase is designed to demonstrate sustainable hot water production from the reservoir between the two wells through a long-term circulation experiment. This article describes the challenges and experiences of drilling the geothermal research well into a deep sedimentary geothermal reservoir. The lessons learnt covers drilling large diameter in sheet silicate bearing rocks, directional drilling through and beneath salty formations, and various mud concepts with the goal of minimized formation damage.
ABSTRACT During the current project phase the geothermal water loop at the Groß Schönebeck site i... more ABSTRACT During the current project phase the geothermal water loop at the Groß Schönebeck site is being set up and short-to long-term hydraulic experiments are performed in the well doublet in order to assess the hydraulic properties and the sustainability of the engineered reservoir. Downhole measurements are carried out during production in order to observe the performance of the stimulated zones and the naturally occurring permeable intervals. The production string has been constructed in order to allow for access to the reservoir with logging tools during fluid production using a new developed Y-tool to bypass the submersible pump. In addition a novel hybrid wireline production logging system for combined measurements with electrical tools (pressure, temperature, flow meter, gamma ray, casing collar locator) and fiber-optic distributed temperature sensing (DTS) has been developed. The results of the first measurement campaigns show that valuable data for the observation and understanding of reservoir flow dynamics can be collected with the new system. The observed hydraulic behavior is mainly controlled by a variable contribution from a hydraulic fracture zone, which appears to be influenced by the production history and induced reservoir processes.
Summary During production of geothermal brine at the Groß Schönebeck research site, large and hea... more Summary During production of geothermal brine at the Groß Schönebeck research site, large and heavy solid particles accumulated within the cased reservoir interval of the production well. A wellbore obstruction at a depth of approximately 4100 m (13,452 ft) was caused by copper-, barite-, lead-, and iron-mineral precipitates with a size of up to 1 cm and elongated coating fragments from the production tubing with a length of up to 10 cm. After a failed reverse-cleanout operation by use of 2-in. coiled tubing (CT), lifting the fluid column within the drillstring (DS) was considered to be the most cost-efficient option to clean out the wellbore while simultaneously minimizing fluid invasion into the reservoir. Here, preliminary considerations for the operation and field observations are presented together with a monitoring concept. The field data are used to calibrate a hydraulic model that is then applied to understand hydraulic processes downhole. On the basis of the hydraulic consi...
... It is intended to use this system of fractures to optimize the total productivity of the well... more ... It is intended to use this system of fractures to optimize the total productivity of the well. The Dethlingen sandstones represent an effective reservoir horizon with a connected porosity of 810%, and an in situ permeability of up to 16.5 mD (Trautwein and Huenges, 2005). ...
... Besides aqueous components, these deep fluids contain various amounts of dissolved gases, mai... more ... Besides aqueous components, these deep fluids contain various amounts of dissolved gases, mainly consisting of nitrogen (N 2 ) and methane (CH 4 ), as well as lower amounts of helium (He), carbon dioxide (CO 2 ), hydrogen (H 2 ), heavy hydrocarbons (C 2+ ), and argon (Ar ...
... Besides aqueous components, these deep fluids contain various amounts of dissolved gases, mai... more ... Besides aqueous components, these deep fluids contain various amounts of dissolved gases, mainly consisting of nitrogen (N 2 ) and methane (CH 4 ), as well as lower amounts of helium (He), carbon dioxide (CO 2 ), hydrogen (H 2 ), heavy hydrocarbons (C 2+ ), and argon (Ar ...
Generation of electricity from geothermal heat is up to now limited to regions characterised by h... more Generation of electricity from geothermal heat is up to now limited to regions characterised by high temperature (T > 150 °C) at lower depths. Beside the temperature, adequate rock types are required which store and supply hot water. A reservoir rock with these profitable ...
In the context of the Geothermal Technology Program at GFZ, the former gas exploration well Gros ... more In the context of the Geothermal Technology Program at GFZ, the former gas exploration well Gros Schonebeck 3/90 (50 km northeast of Berlin) was reopened and deepened to 4309 m depth. For the last 6 years, this well has served as a geothermal in-situ laboratory for in situ experiments and the development of stimulation concepts. The objective of these stimulation operations was to create secondary flow paths and to improve the inflow performance of the well. The well makes the deep sedimentary Rotliegend reservoir accessible, which is characterized by water bearing porous and fractured rocks. To complet e a potential doublet for power generation, the second well Gros Schonebeck 4/05 was drilled in late 2006. At pay -zone depth level the maximum distance between the two wells is approximately 500m. The most promising sandstone layers for stimulation were identified by measured porosity distribution, water saturation and calculated permeability data. This information is a prerequisite...
The Rotliegend of the North German basin is the target reservoir of an interdisciplinary investig... more The Rotliegend of the North German basin is the target reservoir of an interdisciplinary investigation program to develop a technology for the generation of geothermal electricity from low-enthalpy reservoirs. An in-situ downhole laboratory was established at the site of the deep well GrSk 3/90 at Gros Schonebeck with the purpose of developing appropriate stimulation methods to increase permeability of deep aquifers by enhancing or creating secondary porosity and flow paths. The goal is to learn how to enhance the inflow performance of a well from a variety of rock types in low permeable geothermal reservoirs. At present, a research borehole has been drilled to 4.3 km depth and is completed in sedimentary rock formations bearing 150°C. This well (GrSk 3/90), originally completed in 1990, was re-entered in 2000, hydraulically stimulated in 2002 and 2003, and tested in 2003, 2004 and 2005. In April 2006, drilling started on a second well to enhance mass-flow rate from the reservoir us...
Lower Permian siliciclastic sediments and volcanics are widespread strata throughout the Central ... more Lower Permian siliciclastic sediments and volcanics are widespread strata throughout the Central Europe forming deeply buried aquifers in the North German Basin with formation temperatures of up to 150°C. These on average 4000 m deep structures are investigated to develop stimulation methods to increase the permeability by enhancing or creating secondary porosity and flow paths. The final goal is to test the generation of geothermal electricity from such low-enthalpy reservoirs using a doublet of borehole, one to produce deep natural water and the other to re-inject the utilized water. For these purposes, an in-situ downhole laboratory was established in Gros Schonebeck, north of Berlin, Germany. At present, two 4.3 km deep boreholes have been drilled. The first well GrSk 3/90, originally completed in 1990 as a gas exploration well and abandoned due to non-productivity, was re-opened in 2000 and was hydraulically stimulated in several treatments between 2002 and 2005. In 2006, the second well GrSk 4/05, planned for extraction of thermal waters, was drilled in order to realize a doublet system with two hydraulically connected boreholes. It is planned to stimulate in the second well both, the Lower Permian sandstones and the underlying volcanic rock. The resulting engineered reservoir should have an increased productivity being operated with minimized auxiliary energy to drive the thermal water loop and should have a minimized risk of a temperature short circuit of the system during a planned 30-year utilization period. The forthcoming phase is designed to demonstrate sustainable hot water production from the reservoir between the two wells through a long-term circulation experiment. This article describes the challenges and experiences of drilling the geothermal research well into a deep sedimentary geothermal reservoir. The lessons learnt covers drilling large diameter in sheet silicate bearing rocks, directional drilling through and beneath salty formations, and various mud concepts with the goal of minimized formation damage.
ABSTRACT During the current project phase the geothermal water loop at the Groß Schönebeck site i... more ABSTRACT During the current project phase the geothermal water loop at the Groß Schönebeck site is being set up and short-to long-term hydraulic experiments are performed in the well doublet in order to assess the hydraulic properties and the sustainability of the engineered reservoir. Downhole measurements are carried out during production in order to observe the performance of the stimulated zones and the naturally occurring permeable intervals. The production string has been constructed in order to allow for access to the reservoir with logging tools during fluid production using a new developed Y-tool to bypass the submersible pump. In addition a novel hybrid wireline production logging system for combined measurements with electrical tools (pressure, temperature, flow meter, gamma ray, casing collar locator) and fiber-optic distributed temperature sensing (DTS) has been developed. The results of the first measurement campaigns show that valuable data for the observation and understanding of reservoir flow dynamics can be collected with the new system. The observed hydraulic behavior is mainly controlled by a variable contribution from a hydraulic fracture zone, which appears to be influenced by the production history and induced reservoir processes.
Summary During production of geothermal brine at the Groß Schönebeck research site, large and hea... more Summary During production of geothermal brine at the Groß Schönebeck research site, large and heavy solid particles accumulated within the cased reservoir interval of the production well. A wellbore obstruction at a depth of approximately 4100 m (13,452 ft) was caused by copper-, barite-, lead-, and iron-mineral precipitates with a size of up to 1 cm and elongated coating fragments from the production tubing with a length of up to 10 cm. After a failed reverse-cleanout operation by use of 2-in. coiled tubing (CT), lifting the fluid column within the drillstring (DS) was considered to be the most cost-efficient option to clean out the wellbore while simultaneously minimizing fluid invasion into the reservoir. Here, preliminary considerations for the operation and field observations are presented together with a monitoring concept. The field data are used to calibrate a hydraulic model that is then applied to understand hydraulic processes downhole. On the basis of the hydraulic consi...
... It is intended to use this system of fractures to optimize the total productivity of the well... more ... It is intended to use this system of fractures to optimize the total productivity of the well. The Dethlingen sandstones represent an effective reservoir horizon with a connected porosity of 810%, and an in situ permeability of up to 16.5 mD (Trautwein and Huenges, 2005). ...
... Besides aqueous components, these deep fluids contain various amounts of dissolved gases, mai... more ... Besides aqueous components, these deep fluids contain various amounts of dissolved gases, mainly consisting of nitrogen (N 2 ) and methane (CH 4 ), as well as lower amounts of helium (He), carbon dioxide (CO 2 ), hydrogen (H 2 ), heavy hydrocarbons (C 2+ ), and argon (Ar ...
... Besides aqueous components, these deep fluids contain various amounts of dissolved gases, mai... more ... Besides aqueous components, these deep fluids contain various amounts of dissolved gases, mainly consisting of nitrogen (N 2 ) and methane (CH 4 ), as well as lower amounts of helium (He), carbon dioxide (CO 2 ), hydrogen (H 2 ), heavy hydrocarbons (C 2+ ), and argon (Ar ...
Generation of electricity from geothermal heat is up to now limited to regions characterised by h... more Generation of electricity from geothermal heat is up to now limited to regions characterised by high temperature (T > 150 °C) at lower depths. Beside the temperature, adequate rock types are required which store and supply hot water. A reservoir rock with these profitable ...
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Papers by Wulf Brandt