Inga Moeck - Academia.edu (original) (raw)

Papers by Inga Moeck

Environmental Earth Sciences, 2013

ABSTRACT The deep thermal field in sedimentary basins can be affected by convection, conduction o... more ABSTRACT The deep thermal field in sedimentary basins can be affected by convection, conduction or both resulting from the structural inventory, physical properties of geological layers and physical processes taking place therein. For geothermal energy extraction, the controlling factors of the deep thermal field need to be understood to delineate favorable drill sites and exploitation compartments. We use geologically based 3-D finite element simulations to figure out the geologic controls on the thermal field of the geothermal research site Groß Schönebeck located in the E part of the North German Basin. Its target reservoir consists of Permian Rotliegend clastics that compose the lower part of a succession of Late Carboniferous to Cenozoic sediments, subdivided into several aquifers and aquicludes. The sedimentary succession includes a layer of mobilized Upper Permian Zechstein salt which plays a special role for the thermal field due to its high thermal conductivity. Furthermore, the salt is impermeable and due to its rheology decouples the fault systems in the suprasalt units from subsalt layers. Conductive and coupled fluid and heat transport simulations are carried out to assess the relative impact of different heat transfer mechanisms on the temperature distribution. The measured temperatures in 7 wells are used for model validation and show a better fit with models considering fluid and heat transport than with a purely conductive model. Our results suggest that advective and convective heat transport are important heat transfer processes in the suprasalt sediments. In contrast, thermal conduction mainly controls the subsalt layers. With a third simulation, we investigate the influence of a major permeable and of three impermeable faults dissecting the subsalt target reservoir and compare the results to the coupled model where no faults are integrated. The permeable fault may have a local, strong impact on the thermal, pressure and velocity fields whereas the impermeable faults only cause deviations of the pressure field.

Environmental Earth Sciences, 2013

Exploration, Development, and Utilization, 2010

74th EAGE Conference and Exhibition - Workshops, 2012

An adequate comprehensive understanding of the subsurface geology is a pre-requisite for a precis... more An adequate comprehensive understanding of the subsurface geology is a pre-requisite for a precise planning and successful operating of geothermal applications and reduces the financial risks considerably. An exploration concept is needed which is tailored for the geological setting to be evaluated and the level of exploration performed prior to the geothermal exploration. We present examples from ongoing geothermal exploration projects encompassing, for example, studies on the geological structure, including the stress field, on the hydraulic and thermal properties of geological formations, and on the temperature prognoses for target reservoirs.

Tectonophysics, 2014

ABSTRACT The Canadian database on contemporary crustal stress has not been revised systematically... more ABSTRACT The Canadian database on contemporary crustal stress has not been revised systematically in the past two decades. Here we present the results of our new compilation that contains 514 new data records for the orientation data of maximum compressive horizontal stress and 188 data records that were re-assessed. In total the Canadian stress database has now 1667 data records, which is an increase of about 45%. From these data, a new Canadian Stress map as well as one for the Province of Alberta is presented.

London 2013, 75th eage conference en exhibition incorporating SPE Europec, 2013

ABSTRACT Geothermal resources belong to alternative geoenergy systems where heat and electricity ... more ABSTRACT Geothermal resources belong to alternative geoenergy systems where heat and electricity can be produced in a sustainable way with no or low climate gas emissions. Magmatic geothermal systems are potential candidates for economic use due to high temperature and pressure of produced fluids. Indonesia is one of the areas with the highest geothermal potential worldwide. However, greenfield exploration in tropical areas with steep terrain is challenging, especially if geothermal systems are hidden with no obvious surface manifestations. In our study from the Lamongan volcanic areas in East Java we demonstrate an approach of greenfield exploration by fluid chemistry sampling, regional structural geology and petrological analysis. Our results indicate infiltration of seawater through faults from the 20 km nearby coast and a possible heat source in about 3-5 km. The obviously presence of large amounts of fluids indicate a medium temperature geothermal resource. Shallow temperature drilling would clarify the quantity of producible geothermal energy. Our study demonstrates how green field exploration can be started to develop further site specific exploration strategies for hidden geothermal systems in tropical regions.

Geothermics, 2014

In this study tectonic structural features and their hydraulic characteristics of fault zones wer... more In this study tectonic structural features and their hydraulic characteristics of fault zones were integrated into a consistent hydrotectonic model of the Lahendong geothermal reservoir, Indonesia. Moreover, these elements were analysed with respect to their relevance for the operation of the geothermal power plant at initial conditions, i.e. before the start of operation. The complex tectonic setting with volcanic activity provides evidence for relevant structural and hydrogeological elements, such as fault zones, surface spring discharge and joints at different spatial scales. The study area is highly variable with respect to hydraulic properties and chemical composition of the fluids. It consists of two types of fluids. Acid brine water with a pH of around 3 and an electrical conductivity ranging between 4620 S/cm and 9700 S/cm is characteristic for the reservoir in the North with temperatures up to 274 • C. A moderate pH between 4 and 7, an electrical conductivity in the range of 400-1730 S/cm and temperatures of up to 340 • C characterise the southern study area. The Lahendong geothermal field is subdivided into two sub-reservoirs. Faults are less permeable perpendicular to the strike of the faults than parallel to the strike. The characteristics of the complex reservoir system could be explained by the combination of hydrotectonics and hydrogeological parameters. Understanding the permeability distribution along fault zones is crucial to investigate subsurface fluid pathways as well as to sustainably use the reservoir. A compartmentalisation of the reservoir was derived from a stress field analysis of the tectonic elements and from hydrogeological observations. The information on underground fluid flow is essential to understand the subsurface flow of geothermal fluids. Here, the permeability of structures is identified as the limiting factor.

Geothermics, 2010

The design and results of a cyclic hydraulic fracturing experiment performed to enhance the produ... more The design and results of a cyclic hydraulic fracturing experiment performed to enhance the productivity of the geothermal research well at Groß Schönebeck (Germany) are presented. The stimulation carried out in the low-permeability volcanics of the Lower Rotliegend (Lower Permian) included alternating stages with cyclic changes of low and high flow rates with up to 150 L/s over six days in conjunction with the addition of quartz sand to support fracture opening. There was rapid water level increase in an adjacent well due to the stimulation (i.e. water injection). The subsequent production test showed the success of the fracture treatment, with the overall productivity of the treated well being increased by a factor of four.

Chemie der Erde - Geochemistry, 2010

We use a refined 3D structural model based on an updated set of observations to assess the therma... more We use a refined 3D structural model based on an updated set of observations to assess the thermal field of Brandenburg. The crustal-scale model covers an area of about 250 km (E-W) times 210 km (N-S) located in the Northeast German Basin (NEGB). It integrates an improved representation of the salt structures and is used for detailed calculations of the 3D conductive thermal field with the Finite Element Method (FEM).

Canadian Journal of Earth Sciences, 2013

Recent geothermal exploration indicated that the Cambrian Basal Sandstone Unit (BSU) in central A... more Recent geothermal exploration indicated that the Cambrian Basal Sandstone Unit (BSU) in central Alberta could be a potential target formation for geothermal heat production, due to its depth and extent. Although several studies showed that the BSU in the shallower Western Canada Sedimentary Basin (WCSB) has good reservoir properties, almost no information exists from the deeper WCSB. This study investigated the petrography of the BSU in central Alberta with help of drill cores and thin sections from six wells. Porosity and permeability as important reservoir parameters for geothermal utilization were determined by core testing. The average porosity and permeability of the BSU is 10% and <1 × 10 −14 m 2 , respectively. A zone of high porosity and permeability was identified in a well located in the northern part of the study area. This study presents the first published geomechanical tests of the BSU, which were obtained as input parameters for the simulation of hydraulic stimulation treatments. The BSU has a relatively high unconfined compressive strength (up to 97.7 MPa), high cohesion (up to 69.8 MPa), and a remarkably high friction coefficient (up to 1.22), despite a rather low tensile strength (<5 MPa). An average geothermal gradient of 35.6°C/km was calculated from about 2000 temperature values. The temperature in the BSU ranges from 65 to 120°C. Results of this study confirm that the BSU is a potential geothermal target formation, though hydraulic stimulation treatments are required to increase the permeability of the reservoir.

Environmental Earth Sciences, 2013

ABSTRACT The deep thermal field in sedimentary basins can be affected by convection, conduction o... more ABSTRACT The deep thermal field in sedimentary basins can be affected by convection, conduction or both resulting from the structural inventory, physical properties of geological layers and physical processes taking place therein. For geothermal energy extraction, the controlling factors of the deep thermal field need to be understood to delineate favorable drill sites and exploitation compartments. We use geologically based 3-D finite element simulations to figure out the geologic controls on the thermal field of the geothermal research site Groß Schönebeck located in the E part of the North German Basin. Its target reservoir consists of Permian Rotliegend clastics that compose the lower part of a succession of Late Carboniferous to Cenozoic sediments, subdivided into several aquifers and aquicludes. The sedimentary succession includes a layer of mobilized Upper Permian Zechstein salt which plays a special role for the thermal field due to its high thermal conductivity. Furthermore, the salt is impermeable and due to its rheology decouples the fault systems in the suprasalt units from subsalt layers. Conductive and coupled fluid and heat transport simulations are carried out to assess the relative impact of different heat transfer mechanisms on the temperature distribution. The measured temperatures in 7 wells are used for model validation and show a better fit with models considering fluid and heat transport than with a purely conductive model. Our results suggest that advective and convective heat transport are important heat transfer processes in the suprasalt sediments. In contrast, thermal conduction mainly controls the subsalt layers. With a third simulation, we investigate the influence of a major permeable and of three impermeable faults dissecting the subsalt target reservoir and compare the results to the coupled model where no faults are integrated. The permeable fault may have a local, strong impact on the thermal, pressure and velocity fields whereas the impermeable faults only cause deviations of the pressure field.

Environmental Earth Sciences, 2013

Exploration, Development, and Utilization, 2010

74th EAGE Conference and Exhibition - Workshops, 2012

An adequate comprehensive understanding of the subsurface geology is a pre-requisite for a precis... more An adequate comprehensive understanding of the subsurface geology is a pre-requisite for a precise planning and successful operating of geothermal applications and reduces the financial risks considerably. An exploration concept is needed which is tailored for the geological setting to be evaluated and the level of exploration performed prior to the geothermal exploration. We present examples from ongoing geothermal exploration projects encompassing, for example, studies on the geological structure, including the stress field, on the hydraulic and thermal properties of geological formations, and on the temperature prognoses for target reservoirs.

Tectonophysics, 2014

ABSTRACT The Canadian database on contemporary crustal stress has not been revised systematically... more ABSTRACT The Canadian database on contemporary crustal stress has not been revised systematically in the past two decades. Here we present the results of our new compilation that contains 514 new data records for the orientation data of maximum compressive horizontal stress and 188 data records that were re-assessed. In total the Canadian stress database has now 1667 data records, which is an increase of about 45%. From these data, a new Canadian Stress map as well as one for the Province of Alberta is presented.

London 2013, 75th eage conference en exhibition incorporating SPE Europec, 2013

ABSTRACT Geothermal resources belong to alternative geoenergy systems where heat and electricity ... more ABSTRACT Geothermal resources belong to alternative geoenergy systems where heat and electricity can be produced in a sustainable way with no or low climate gas emissions. Magmatic geothermal systems are potential candidates for economic use due to high temperature and pressure of produced fluids. Indonesia is one of the areas with the highest geothermal potential worldwide. However, greenfield exploration in tropical areas with steep terrain is challenging, especially if geothermal systems are hidden with no obvious surface manifestations. In our study from the Lamongan volcanic areas in East Java we demonstrate an approach of greenfield exploration by fluid chemistry sampling, regional structural geology and petrological analysis. Our results indicate infiltration of seawater through faults from the 20 km nearby coast and a possible heat source in about 3-5 km. The obviously presence of large amounts of fluids indicate a medium temperature geothermal resource. Shallow temperature drilling would clarify the quantity of producible geothermal energy. Our study demonstrates how green field exploration can be started to develop further site specific exploration strategies for hidden geothermal systems in tropical regions.

Geothermics, 2014

In this study tectonic structural features and their hydraulic characteristics of fault zones wer... more In this study tectonic structural features and their hydraulic characteristics of fault zones were integrated into a consistent hydrotectonic model of the Lahendong geothermal reservoir, Indonesia. Moreover, these elements were analysed with respect to their relevance for the operation of the geothermal power plant at initial conditions, i.e. before the start of operation. The complex tectonic setting with volcanic activity provides evidence for relevant structural and hydrogeological elements, such as fault zones, surface spring discharge and joints at different spatial scales. The study area is highly variable with respect to hydraulic properties and chemical composition of the fluids. It consists of two types of fluids. Acid brine water with a pH of around 3 and an electrical conductivity ranging between 4620 S/cm and 9700 S/cm is characteristic for the reservoir in the North with temperatures up to 274 • C. A moderate pH between 4 and 7, an electrical conductivity in the range of 400-1730 S/cm and temperatures of up to 340 • C characterise the southern study area. The Lahendong geothermal field is subdivided into two sub-reservoirs. Faults are less permeable perpendicular to the strike of the faults than parallel to the strike. The characteristics of the complex reservoir system could be explained by the combination of hydrotectonics and hydrogeological parameters. Understanding the permeability distribution along fault zones is crucial to investigate subsurface fluid pathways as well as to sustainably use the reservoir. A compartmentalisation of the reservoir was derived from a stress field analysis of the tectonic elements and from hydrogeological observations. The information on underground fluid flow is essential to understand the subsurface flow of geothermal fluids. Here, the permeability of structures is identified as the limiting factor.

Geothermics, 2010

The design and results of a cyclic hydraulic fracturing experiment performed to enhance the produ... more The design and results of a cyclic hydraulic fracturing experiment performed to enhance the productivity of the geothermal research well at Groß Schönebeck (Germany) are presented. The stimulation carried out in the low-permeability volcanics of the Lower Rotliegend (Lower Permian) included alternating stages with cyclic changes of low and high flow rates with up to 150 L/s over six days in conjunction with the addition of quartz sand to support fracture opening. There was rapid water level increase in an adjacent well due to the stimulation (i.e. water injection). The subsequent production test showed the success of the fracture treatment, with the overall productivity of the treated well being increased by a factor of four.

Chemie der Erde - Geochemistry, 2010

We use a refined 3D structural model based on an updated set of observations to assess the therma... more We use a refined 3D structural model based on an updated set of observations to assess the thermal field of Brandenburg. The crustal-scale model covers an area of about 250 km (E-W) times 210 km (N-S) located in the Northeast German Basin (NEGB). It integrates an improved representation of the salt structures and is used for detailed calculations of the 3D conductive thermal field with the Finite Element Method (FEM).

Canadian Journal of Earth Sciences, 2013

Recent geothermal exploration indicated that the Cambrian Basal Sandstone Unit (BSU) in central A... more Recent geothermal exploration indicated that the Cambrian Basal Sandstone Unit (BSU) in central Alberta could be a potential target formation for geothermal heat production, due to its depth and extent. Although several studies showed that the BSU in the shallower Western Canada Sedimentary Basin (WCSB) has good reservoir properties, almost no information exists from the deeper WCSB. This study investigated the petrography of the BSU in central Alberta with help of drill cores and thin sections from six wells. Porosity and permeability as important reservoir parameters for geothermal utilization were determined by core testing. The average porosity and permeability of the BSU is 10% and <1 × 10 −14 m 2 , respectively. A zone of high porosity and permeability was identified in a well located in the northern part of the study area. This study presents the first published geomechanical tests of the BSU, which were obtained as input parameters for the simulation of hydraulic stimulation treatments. The BSU has a relatively high unconfined compressive strength (up to 97.7 MPa), high cohesion (up to 69.8 MPa), and a remarkably high friction coefficient (up to 1.22), despite a rather low tensile strength (<5 MPa). An average geothermal gradient of 35.6°C/km was calculated from about 2000 temperature values. The temperature in the BSU ranges from 65 to 120°C. Results of this study confirm that the BSU is a potential geothermal target formation, though hydraulic stimulation treatments are required to increase the permeability of the reservoir.