Damien Bonté

Subsurface temperature of the onshore Netherlands: new temperature dataset and modelling

Subsurface temperature is a key parameter for geothermal energy prospection in sedimentary basins. Here, we present the results of a 3D temperature modelling using a thermal-tectonic forward modelling method, calibrated with subsurface temperature measurements in the Netherlands. The first step involves the generation of a coherent dataset of temperature values for the calibration of the model. In the Netherlands, most of the available measurements (98.8%) are BHT measurements and therefore need to be corrected from the thermal perturbation created during drilling. The remaining 1.2% is composed of DST measurements, which closely resemble the formation temperature (i.e., ±5 °C). The resulting dataset, after correction, gives a total number of 1293 values in 454 wells. Included in this dataset are 412 highly reliable values corrected with the Instantaneous Cylinder Source (ICS) method and 829 values of a lower reliability corrected with the AAPG method. In addition to the corrected values, 52 DST values in 26 wells are available from the Dutch subsurface. The average thermal gradient of this whole dataset is 31.3 °C/km with a surface temperature of 10.1 °C. The second step in the modelling process was the generation of a 3D forward model that focuses on calculating the temperature distribution of the sedimentary basin fill, taking into account the basin evolution of the past 20 Myrs and thermal properties and processes of the whole lithosphere. From the 3D thermal model, we extracted 2D cross sections across well locations to compare model temperatures with calibration data. Furthermore, we present vertical profiles, isodepth maps and temperature projection on geological layers, to discuss the relationship between temperature and geology. Anomalies in this relationship can have several causes and include: 1) the extreme thermal conductivity and complex geometry of the Zechstein salt; 2) enhanced radiogenic heat production of the upper crust due to magmatic intrusions. In addition, our model supports earlier findings that shallow hydrothermal convection in highly permeable sediments can effectively lower thermal conductivity and temperatures in shallow sediments.

Reservoir characterisation of aquifers for direct heat production: methodology and screening of the potential reservoirs for the Netherlands

Geothermal low enthalpy heat in non-magmatic areas can be produced by pumping hot water from aquifers at large depth (>1 km). Key parameters for aquifer performance are temperature, depth, thickness and permeability. Geothermal exploration in the Netherlands can benefit considerably from the wealth of oil and gas data; in many cases hydrocarbon reservoirs form the lateral equivalent of geothermal aquifers. In the past decades subsurface oil and gas data have been used to develop 3D models of the subsurface structure. These models have been used as a starting point for the mapping of geothermal reservoir geometries and its properties. A workflow was developed to map aquifer properties on a regional scale. Transmissivity maps and underlying uncertainty have been obtained for 20 geothermal aquifers. Of particular importance is to take into account corrections for maximum burial depth and the assessment of uncertainties. The mapping of transmissivity and temperature shows favorable aquifer conditions in the northern part of the Netherlands (Rotliegend aquifers), while in the western and southern parts of the Netherlands aquifers of the Triassic and Upper Cretaceous / Jurassic have high prospectivity. Despite the high transmissivity of the Cenozoic aquifers, the limited depth and temperature reduce the prospective geothermal area significantly. The results show a considerable remaining uncertainty of transmissivity values, due to lack of data and heterogeneous spatial data distribution. In part these uncertainties may be significantly reduced by adding well test results and facies parameters for the map interpolation in future work. For underexplored areas this bears a significant risk, but it can also result in much higher flowrates than originally expected, representing an upside in project performance.

ThermoGIS: An integrated web-based information system for geothermal exploration and governmental decision support for mature oil and gas basins

In the recent years the use of geothermal energy through implementation of low enthalpy geothermal production systems for both electricity and heating have been growing rapidly in north-western Europe. Geothermal exploration and production takes largely place in sedimentary basins at depths from 2 to 5 km. Geothermal activities can take considerable advantage of a wealth of existing oil and gas data. To governmental bodies, such as geological surveys, it is a major challenge to put relevant oil and gas data and derived subsurface structural, temperature, and flow property models available to the geothermal community and to facilitate in quantitative assessment of geothermal potential of targeted areas, for both heat and electricity production (EGS) . In order to face this challenge, TNO has developed a public web-based 3D information system connected to a geothermal performance assessment tool. The public information system (thermoGIS) includes high resolution 3D geological models covering the complete onshore of the Netherlands, outlining key geothermal reservoirs and allowing to assess relevant parameters and underlying uncertainties therein. State-of-the-art 3D modeling techniques have been used and developed to obtain the reservoir structures, flow properties and temperatures, using constraints from over a thousand deep wells, and detailed subsurface mapping from 3D and 2D seismic. Users can obtain key reservoir parameters, and underlying uncertainties at any location and for any reservoir. In an automated workflow these parameters are fed into the performance assessment tool, in order to asses the probability of success to meet minimum requirements on key performance indicators such as Coefficient of Performance (COP), power produced, and Unit Technical Cost (UTC). The use of the ThermoGIS will aid exploration business decisions and Dutch governmental institutions, law makers and insurance companies.

Regional Assessment of Aquifer Permeability - The Importance of Burial Anomalies

Permeability of aquifers is a key parameter for geothermal doublet performance. Commonly it is assumed that porosity is marked by a decrease with depth of the aquifer as a result of mechanical compaction. Burial depth should therefore be used in the spati

Temperature Model for Geothermal Exploration in Sedimentary Basins - Application to the Netherlands

Key factors to successful geothermal exploration include sufficiently high temperatures and sufficiently high sustainable production rates. This study focuses on the first of these two by modelling the temperature in the sedimentary basins of the Netherla

High Resolution Temperature Models for Geothermal Exploration – Methods and Application to the Netherlands

This paper focuses on high resolution temperature models for temperature prediction in mature oil and gas basins. Besides well and log data, numerical thermal basin modelling is required to predict subsurface temperature. For detailed 3D models (i.e. invo

Iberian Crustal Stress Field and Temperatures Assessed from Tectonic Studies – Meaning for Geothermal Exploration?

Granite rocks are considered a prime target for EGS (Enhanced Geothermal Systems) as they are marked by high geothermal gradients, caused by radiogenic heat production, and are well suited to be used for geothermal doublets using hydraulic fracturing. Cri

Tectonic Heat Flow during the Permo-carboniferous Orogenic Collapse – Constraints by Tectonic and Maturity Trend Analysis

Basement heat flow is one of the most influential parameters on basin maturity. Although rapid progress has been made in the development of tectonic models capable of modeling the thermal consequences of basin formation, these models are used in basin mod

Tectonic heat flow modelling for basin maturation - Implications for frontier areas in the mediterranean

Basement heat flow is one of the most influential parameters on basin maturity. Although rapid progress has been made in the development of tectonic models capable of modelling the thermal consequences of basin formation, these models are hardly used in basin modelling. To better predict heat flows we have developed a multi-1D probabilistic tectonic heat-flow model, incorporating a variety of tectonic scenarios (including rifting, underplating and mantle upwelling). The model has been applied for a range of basin settings, and predicted temporal and spatial heat flow variations are well in accordance with observations on heat flow for specific tectonic settings. In the Mediterranean observed heat flow is markedly heterogenous, ranging from values from as low as 30mW m-2 up to 150 mW m-2, having major implications for basin temperature and maturation levels. Tectonic models for heat allow to asses geodynamic causes for these varations and aid considerably in constrining spatial and temporal variations in heat flow. In particular modelling results indicated that the interplay of rifting, underplating, back-arc extension, has resulted in much stronger temporal and spatial tectonic heat-flow variations than hitherto assumed.

Tectonic Heat Flow Models - Workflow and Cases

To obtain a pragmatic workflow solution for tectonic heat flow prediction, we have developed in the recent years a multi-1D probabilistic tectonic heat flow model, which is capable of calculating tectonic heat flows, incorporating a variety of tectonic scenarios (including rifting, underplating, mantle upwelling). The model has been applied for a range of basin settings. For (frontier) deep water basins in the Caribbean and Mediterranean regions, we show that basin maturation is significantly higher and occuring much earlier when adopting tectonic heat flow instead of a constant heat flow. For mature basins such as in the Netherlands, we show that tectonic heat flow scenarios considerably aid in identifying and understanding of unexplored play systems, by putting temporal and spatial constraints on paleo heat flow. In particular modelling results indicate that the interplay of rifting, underplating and foreland formation and inversion, has resulted in much stronger temporal and spatial tectonic heat flow variations than hithertoo assumed.