In the context of the energy transition, rapid development of the geothermal sector in the Netherlands has to take place. The first steps have been taken by establishing the Green Deal UDG between multiple industrial consortia, which agree to share knowledge on the research and use of ultra-deep geothermal energy . The Dinantian carbonates are of interest for the deep geothermal wells, because of their high geothermal potential. This research project provides a case study of the Californië geothermal doublets in Limburg (NL), which are currently the only geothermal wells in the Netherlands producing from the Dinantian carbonates. However, the static and dynamic model prove that the Devonian Bosscheveld formation and Condroz group are also part of the reservoir formation. Due to the tight matrix of the reservoir rocks, the permeability is believed to be fracture and karst (meteoric and hydrothermal) driven. The goal of this Thesis is to create a static and dynamic model of the reservoir that confirms the current production data (history match) and that explores the development of the geothermal potential of the reservoir in space and time. The static and dynamic reservoir model are based on a limited amount of well and seismic data, which forms the main challenge in this project. A framework of assumptions has been created to construct the model and a scenario- based approach has been applied to construct a best case scenario that matches the production data. A key element in the static reservoir model is the Tegelen fault. To estimate the impact of the Tegelen fault on the permeability distribution in the reservoir, a fieldwork in an analogue carbonate quarry has been executed. The results are applied in the static model. The dynamic results in this study show that the permeability configuration applied in the best case scenario results in BHP, flow rate and temperature values that are of the correct order of magnitude and within an acceptable error margin of the production data. Multiple sensitivities have been simulated to determine the range of parameters that may cause an inaccuracy in the results. Additional data acquisition is necessary to validate and optimize the static model, which will result in a dynamic model with an improved history match and a larger predictive power for future production and reservoir management.

The subsurface of Groningen gas field composed of several faults. The continuous production has been resulting in several micro-seismicity activities, particularly for the past decades. One of the reasons for the production-induced-seismicity is fault reactivation at depth. The fault that initially in the non-active state becomes active and starts slipping due to pore fluid extraction. The modelling of fault reactivation induced by production can be simulated by coupling of flow and geomechanics. The project studies the coupling of flow and geomechanics for an idealistic subsurface model with fault. The flow occurs due to pore pressure depletion and is predicted by solving mass conservation. The corresponding deformation is estimated by momentum balance equation. The observation will be limited to rock deformation that is quantified by effective stress and displacement on the fault due to a pressure change in the subsurface. The simulation is performed using Stanford's Automatic Differentiation General Purpose Reservoir Simulator (ADGPRS). In the proposed model, the flow equation is discretised using finite volume method, and poromechanics is discretised by finite-element Galerkin's approach. Both problems share the same grid model, and there is no error associated with the information exchange. The coupled problem is being solved fully implicitly where flow and mechanics formulation are solved simultaneously. The case study for the simulation is a simplified Groningen subsurface model with a fault zone. The impact of variability in production dynamic on fault reactivation is studied. The variations in production rate and production strategy are applied in different formation configurations. It is found that the correlation between the production rates and the stress state in the subsurface depends on the formation offset. However, the stress field does not depend on continuity of the production scheme. Several aspects including the presence of Gas-Water contact in the model was studied in this project as well.

Faults can both improve producibility and fluid flow in hydrocarbon reservoirs, and cause leakage and instabilities in sealing layers. For this reason it is of importance to create a multiscale understanding of the drivers behind deformation, and how deformation is accommodated. Carbonates have always been of interest to the oil and gas industry as carbonates house some of the world’s largest oil and gas reserves. Understanding, and maybe predicting the geometries and fracture types could therefore be of integral importance to the E&P industry. For that reason two seismic datasets were provided for analysis on both a Fault Network Scale (faults over >1km in length) and a Small Seismic Scale (faults <1km in length). For the Fault Network Scale Petrel was used for seismic interpretation of the faults, as only the largest faults were interpreted in both seismic datasets. For the Small Seismic Scale OpendTect was used for enhanced seismic interpretation. OpendTect’s fracture enhancing attributes and filters provide seismic images with a high level of detail. These attributes were applied to 5 generated steering-cubes, to display even the smallest faults. The results on the Fault Network Scale show that most faults are caused by regional tectonics. However in areas where salt is underlying the chalks of the Chalk Group, halokinesis is the main driver of deformation. On the Small Seismic Scale drivers behind deformation differ more, fluid expulsion drives polygonal faulting patterns in areas where salt tectonics or far field extensional tectonics are absent. Towards halokinesis structures salt tectonics will be the main driver behind deformation. In areas where salt is absent, far field tectonics can still influence chalks forming fractures either parallel or perpendicular to the major surrounding faults.

The Southern Chotts and Jeffara Basins are situated within the Saharan Domain of Central Tunisia, North Africa. The Southern Chotts Basin hosts reservoirs within the Triassic, Permian and Ordovician units that contain significant hydrocarbon accumulations whilst the Jeffara Basin contains outcrop analogues of the same hydrocarbon­bearing formations. The basins experienced a late Hercynian shortening phase which involved the uplift of a major topographic high (Tebaga de Medenine). This high, in conjunction with a older regional high, the Telemzane Arch influenced the deposition and geometry of the Permian and Triassic units across both basins. This shortening event is characterised at the scale of hundreds of meters by E­W striking folds into which the mid­late Triassic and early Jurassic units are deposited. The folding is also observed at field scale (10’s meters) through small fault­related folds in the Permian deposits of the Tebaga de Medenine. This late Hercynian phase occurs between the late Permian and early Jurassic in the basins. Fracture data collected from the upper Permian and lower Triassic units (Jeffara Basin) provides an analogue to the fracture networks at depth (Southern Chotts Basin) in the Paleozoic reservoirs. A conjugate fracture system observed in the field (from fracture pavements) corroborates with the interpretation of regional shortening in the basins. Seismic attribute analysis on depth slices in the Paleozoic reservoirs also shows the conjugate system at depth. This analysis is integrated with outcrop fracture data and FMI data from wells to create an open fold distributed fracture model of the system in the basins. This model indicates the main driver for fracture generation in the region is folding and is used to predict the fracture networks at depth. This is undertaken using discrete fracture network (DFN) modelling of the subsurface. This model is integrated with a deterministic model from the seismic time slices to create a hybrid predictive fracture model of the early Paleozoic reservoirs. Analytical aperture modelling of the fracture model demonstrates the fractures varied in openness depending on orientation and fracture length. The conjugate set orientated at 240∘and longer joints detected from seismic attributes presented the widest aperture size. These fractures in the subsurface at implications on the transmissibility of the reservoirs, especially Permian units which have low bulk rock permeability and the lower Triassic (TAGI) sequences which are susceptible to compartmentalisation.

Geological surveying is a common practice performed by geologists nowadays. Determining layer orientation parameters and identifying folds are examples of features needed in order to create a geological map or model of the (sub) surface. Surveying is expensive and time consuming, therefore such survey is recently being investigated and implemented in 3D point clouds. This thesis provides a method to quickly obtain geological information such as orientation parameters and fold information in a semi-automated manner. Obtaining this parameters is currently still a difficult problem because of data density and calculation complexity. Fast and reliable are terms important for the created method. Large point clouds can easily jam a system and reliability is important for usability and compatibility of the created results. A method is designed which can handle bulk data, performing operations such as filtering and noise reduction assisting in data handling. Next to general calculations such as roughness filtering, intensity filtering and directional filtering of generated normals, the use of a Graphical User Interface (GUI) greatly improves the reliability of the feature calculations. The user selects areas which are potentially interesting for acquiring layer orientation information, which are then analyzed by the method itself creating a base for determining the layer orientation parameters. This base is then used to attempt the reconstruction of the bedding layers of the geological outcrop resulting in the desired geological features. The method has been tested on the “La Charce” dataset and the “Meso-scaled fold” dataset for method validation and on the “Pradelle 2” dataset for compatibility checking. Average calculation time is with approximately 10 minutes reasonable fast. The acquired dip direction of approximately 156 degrees is very similar to that of Prentice (2017), Bisschop (2017) and the fieldwork teams of 2016. The dip angle of 52 degrees is on the other hand off compared to validation results. The layer thickness calculations are comparable, all theses show that the bulk thicknesses between ~30 and ~70 cm. The fold dataset has no validation results but the images look good. It has to be mentioned that all results obtain commission and omission errors but these are in no comparison to the results which are correct.

Hydrocarbon or geothermal reservoir often consists of several rock layers from different lithology. The various lithologies have their own number of mechanical properties and the layering effect introduced the term of mechanical contrast, which represents the ratio of rock strength between adjacent layers. Mechanical contrast and confining pressure highly influence the fracture behavior in the layered rocks. In this study, fractures in layered rocks are investigated, starting with its geometry and also the stress field contributed to the fracture generation and development. The fracture geometry such as fracture length, average aperture, aperture distribution and orientation are quantified in a two dimension slice image. The study focused on comparing the fracture behavior when (a) the layered rock compositions are the same between samples with increasing confining pressure or (b) the different compositions of layered rocks (different mechanical contrast) between samples in the same confining pressure. The results show that fracture tends to propagate through layer interface when the mechanical contrast between adjacent layers and the confining pressure are low. The fracture in the weak layer developed at a gentler dip (shear fracture) with higher fracture aperture compared to the ones in the strong layer which almost vertical (tensile fracture). In addition, the shear fracture in the weak layer usually accompanied by the zone of cataclastic flow while the tensile fracture has a more clear pathway for fluid flow. However, mode I opening/tensile fractures are less likely to affect fluid flow in the reservoir because their aperture is insignificant at depth. While in mode II sliding/shear fractures, only several parts along the fracture that can provide the open space, which depend on the presence of jogs and irregularities on the fracture surfaces. The results from fracture measurements show that in the weak layer, average aperture and aperture distribution will reduce with the increasing of confining pressure, but increased with the increasing of mechanical contrast. Average fracture aperture and distribution have a significant role in capillary pressure. The higher average aperture will reduce the amount of pressure needed to flow the fluid, while a higher number of aperture standard deviation (aperture distribution) has a contrasting effect. The average aperture has a bigger impact on capillary pressure compare to aperture distribution. Thus, by increasing the confining pressure or decreasing the mechanical contrast, the required pressure for fluid to flow is increasing. Furthermore, the numerical modeling is performed by imitating the rock mechanical properties and the fracturing conditions from the laboratory experiment. The results show that under compressive stresses, the layered rocks still generate tensile stresses around the interface within the strong layer. The tensile stresses occur because of the stress transfer between adjacent stiff and soft layer with a bonded interface. The presence of tensile stress and the crack-tip stress are responsible for the generation of the tensile fracture in the strong layer for all samples. The effect of varying the number of confining pressure, Poisson’s ratio and Young’s modulus on the tensile stresses distribution are also performed. The sensitivity study shows that Poisson’s ratio has a more significant impact compared to Young’s modulus on both maximum tensile stress and thickness of tensile region. Higher Poisson’s ratio resulting in higher tensile stresses, while on Young’s modulus it depends on the contrast between adjacent layers rather than the magnitudes. Understanding the fracture behavior in layered rocks is beneficial for reservoir characterization, as fractures can enhance the permeability and providing vertical connectivity between isolated reservoirs. Accurately interpret 3D natural fracture distribution can help the estimation of the resource and recoverable potential early in field life. It will also contribute to optimizing the well placement and completion design for efficient production planning.

The production and injection of fluids from and in reservoirs leads to changes in the in-situ stress in the subsurface. This can cause reservoir compaction, subsidence, fault reactivation and / or seismicity. As these effects may greatly influence society it is of importance to find accurate methods to describe them so they can be predicted or even better, mitigated. This thesis discusses a new analytical approach to calculate stress in the subsurface which incorporates the effects of differential compaction on the initiation of fault reactivation. This new approach is named Differential Compaction Loading (DCL) and the reason for its development is due to discrepancies observed between calculations using the Mohr-Coulomb failure criterion, also known as Poro-elastic Loading (PEL), and field observations. Geomechanical modelling was performed to assess fault failure sensitivity to a range of geometrical aspects as well as reservoir and fault properties. From this analysis, focusing on the reactivation pressure at which failure first occurs, an empirical sense of sensitivity was established. It was found that for the examined variations in the geometry the fault dip angle resulted in the largest spread in reactivation pressure. For the examined reservoir and fault properties, the friction angle was found to have the largest sensitivity. With these results it was possible to improve the estimates of essential parameters within the analytical approach, yielding a better fit between analytical and modelled solutions. These solutions lie closer to field observations. Hence, the new method of DCL shows a great improvement in calculation of stresses in the subsurface, compared to the method of PEL. This calibrated analytical approach allows for a quick assessment of the fault stability within a reservoir. Additionally, through the results from the geomechanical model new insights were obtained into the way stresses change and behave when a reservoir is depleted. The rotation of the principal stresses for each level of depletion was quantified and a new definition of the critical fault angle, the dip angle which will fail first, was derived. This links the depletion pressure and related rotation angle directly to a value of the new critical fault angle when DCL is present. Ultimately, these new insights into fault failure behaviour of boundary faults could be a useful tool in the step towards prediction and mitigation of production or injection related seismicity.

This report contains the results of the two thesis studies that finalise a combined MSc--programs of Reservoir Geology and Science Communication. The first part of the report comprises the multi-scale data (kilometers to meters scale) analysis of a) the large--scale architecture of the subsurface Daly Waters Arch which was obtained from seismic data interpretation; and b) fracture pattern characterisation by outcrop measurements and drone imagery in the Tomkinson Province. Both the Daly Waters Arch and the Tomkinson Province are located in the largely undeformed Palaeo-- to Meso--Proterozoic Greater McArthur Basin in the Northern Territory, Australia. In July 2019, a geological fieldwork was conducted in the Tomkinson Province to collect the fracture data with the drone. In this research, the Daly Waters Arch and the Tomkinson Province have been geologically linked based on seismic and fracture data. By discussing analog cases of far-field deformation, these results have been placed in a larger context of large--scale basin deformation. The second part of the report focuses on the Netherlands, where ambitious goals have been set for the implementation of geothermal energy in the energy transition. During the gas production in Groningen, a negative social perspective towards mining operations, in general, was developed. For the implementation of geothermal energy, an approach for the communication of technical uncertainties between the initiators and the local public of a geothermal project is designed in this study. Technical uncertainties that are present in geothermal energy implementation in the Netherlands have been identified during semi-structured expert-interviews with different stakeholders in the spectrum of geothermal energy. The approach addresses guidelines for the communication of the context, the goal, the technical uncertainties present in the geothermal project, the main communicating actors, their reference frames, and the situation in which the communication process takes place.

The primary reservoirs present in the Southern Chotts Basin, Central Tunisia, are located within Triassic, Permian and Ordovician units. They are mainly sourced by the Silurian -- Lower Devonian Fegaguira formation and its Hot Shale member. Late Paleozoic exhumation has eroded part of the Palaeozoic package, removing the Early Devonian -- Carboniferous and most of the Permian deposits in the Southern Chotts Basin. This resulted in a diachronous unconformity in the present-day stratigraphy and represents significant uncertainties. This study presents a reconstruction of the tectonic and thermal history of the Southern Chotts Basin and the subsequent impact on source rock thermal maturation, with an emphasis on the Hercynian exhumation. Implications on the petroleum systems in the basin are evaluated by means of a migration study. Investigation of adjacent analogue basins allows estimation of the amount of initially deposited sediment in the Early Devonian -- Permian. Calibration with vitrinite reflectance data minimizes exhumation uncertainties in the basin history and indicates ca. $2300$ m sediment eroded during the Hercynian phase. Subsidence analysis shows similar subsidence patterns throughout the area of interest since the Mesozoic. This argued to use a single set of high and low case initial deposition estimates, calibrated with vitrinite reflectance, in source rock maturation modelling. Source rock maturation modelling in the kitchen area indicates hydrocarbon generation occurs in two phases separated by a phase of stable maturity during Hercynian exhumation. Maturation in the kitchen area is found to currently be in the condensate -- wet gas zone. Migration modelling shows that Paleozoic generation in the northern and northeastern portion of the basin primarily sourced the present-day hydrocarbon discoveries. High capillary entry pressures in overlying Fegaguira shales forced hydrocarbons generated in the Hot Shale member to migrate downward into porous Ordovician units. Subsequently, hydrocarbons laterally migrate up-dip into local traps, where they remain trapped wherever the overlying source rock is preserved during Hercynian exhumation. The Ordovician units acts as a reservoir, and as a carrier bed to source present-day accumulation in the Triassic TAGI unit. A newly identified petroleum system primarily hosts accumulations in lower shoreface Ordovician El Atchane deposits, overlain by the Fegaguira and Hot Shales. Simulated hydrocarbon accumulations and projection of shoreface deposits throughout the area of interest mark a sweet spot area with significant reservoir potential in structural traps. Recommendations are given to further investigate the potential of this system.

Knowledge of the state of stress is of significant importance to have a thorough understanding of subsurface geomechanics. The World Stress Map (WSM) is the main source of present-day stress data in Western Europe and indicates a regional NW-SE maximum horizontal stress (SH) trend for the Netherlands. However, for more local studies the WSM lacks the required resolution. Therefore, the first objective of this research is to expand the Dutch Stress Map (DSM) database in which SH orientations are collected. As such, a better understanding can be obtained of the horizontal stress field with depth and the SH orientations that deviate from the regional trend. In addition, this research aims to characterize the in-situ stress regimes with depth in the Groningen field, using different one-dimensional stress models. This research first highlights the importance of the stress state and indicates which in-situ stress information is currently lacking in the Netherlands. Moreover, it is shown how stress-induced borehole features serve as basis for the determination of horizontal stress directions. The datasets used to expand the DSM database are presented, after which an extensive analysis is performed on the collected SH orientations. Subsequently, the stress magnitudes are quantified by studying the sensitivity of the in-situ stress regime to different 1D stress models. Moreover, the workflow is described for developing a 3D geomechanical model, which can serve as basis for future studies. The research shows that the DSM database is expanded with 86 new boreholes across the Dutch on- and offshore regions. The analysis of the database indicates a dominant NW-SE SH orientation, both spatially and with depth. In most stratigraphic groups, the SH direction falls within the range of 315° ±22.5°, although a larger degree of variation is observed in the post-salt stratigraphies. On a local scale, two case studies show that SH orientations, which deviate from the regional NW-SE trend, can be related to the presence of a salt structure and a normal fault. The 1D in-situ stress models all indicate a normal faulting stress regime at reservoir depth (Rotliegend) and deeper. In the interval between the reservoir and Earth’s surface, no unambiguous stress regime is identified as the regime is more sensitive to the different boundary conditions applied.

In the northern part of the Netherlands, the exploitation of gas fields has been inducing small earthquakes, causing damage to existing buildings. With the aim of preventing consequences to people and structures, the VIIA Groningen project deals with CC2 and CC3 buildings retrofit and provides reinforcement measures when necessary. As part of the structural response assessment, after the NPR 9998 (2015), and eventual special cases from the latest NPR 9998 (2017), non-linear time history analyses (NLTH) are executed, comprising seismic ground response analysis (SRA). The propagation of seismic waves through a 1D soil column is highly dependent on the characteristics of the materials constituting the soil deposits. Hence, it is essential to correctly interpret the soil properties, in order to achieve realistic representations of the in-situ conditions. To interpret the soil layering at a particular site, the Cone Penetration Test (CPT) is commonly used in Groningen. It offers a quick, economical and reliable measurement of ground conditions. However, the CPT-based correlations used to estimate soil properties can constitute a source of uncertainty if not coupled with full-scale testing and laboratory measurements. The present thesis, thus, deals with the verification and the improvement of two CPT-based correlations used for soil interpretation in Gronigen specifically. The research study focuses on the mathematical models related to the plasticity index (PI) and the undrained shear strength (Su) of soft soils present in Groningen. A comprehensive database of factual data was compiled in order to group various test types and provide a best-estimate of soil properties for different soil types using geotechnical and stratigraphic considerations. Secondly, a statistical characterisation of data-sets was performed to obtain insight on the correlations performance in relation to the in-situ and laboratory measurements. Based on the outcomes of the statistical comparison, analytical and regression analyses were carried out with the scope of improving the correlation that was deemed to be inadequate. Additionally, a sensitivity analysis was executed to investigate the influence of three relevant soil properties on the seismic ground response from a typical soil profile from Groningen. The parameters assessed are: plasticity index (PI), undrained shear strength (Su), and shear wave velocity (Vs). Results indicate that, among the considered CPT-based correlations, the equation for PI from Cetin and Ozan (2009) is adequate in some cases. The geotechnical units sandy Clay and Loam show good correspondence with the factual data. On the other hand, the PI predicted with such relation tends to be lower than the laboratory measurements for the remaining soil units (e.g. clean Clay, silty Clay, OC Clay). Conversely, the PI behind the models implemented in the NPR 9998 (Bommer et al., 2017a) are in closer agreement to the factual data, however, the PI from some soil units can be further improved with the findings from the present research. For the interpretation of Su, the SHANSEP model from Ladd and Foott (1974) is frequently used. The available factual data showed a poor correspondence with the predicted Su values. Therefore, the SHANSEP model was further studied to calibrate its parameters for different soil types. From the available triaxial consolidated undrained laboratory tests, best-estimate of SHANSEP coefficients were obtained for the main soil types (clean, sandy, and silty Clay). New Su values were validated with the in-situ and laboratory measurements. In this context, it is confirmed that the dependency of Su on the overconsolidation ratio (OCR) is crucial. Moreover, the estimation of OCR from CPT measurements (following the Mayne, 2014, procedure) is found to be partially inaccurate within the SHANSEP framework and needs to be studied in more detail. Engineering aspects related to the topics of the research are discussed and considerations regarding the applicability of the new correlations are provided. Furthermore, the present study gives indications about the usefulness of a number of test types, suggesting direction for future soil investigations. In addition, look-uptables for PI and Su, based on the outcomes of the present research, are provided as part of the recommendations for implementation in the soil parameter interpretation for the Groningen region.

The aim of this study is to reduce the risk of the ongoing Geothermal exploration effort in Geneva Basin by estimating the influence of the natural fracture on the reservoir properties. A Discrete Fracture Network (DFN) was generated to resemble the fracture network in the Lower Cretaceous carbonate reservoir. The DFN modelling approach is using a novel workflow that is based on a geomechanical forward modelling simulation approach. Two 2D seismic lines and well data, including interpreted fractures using Borehole Image (BHI) log, were used to prepare the model inputs. Some results were derived from the fracture data that were also used to prepare the model inputs. In general, the fracture data have fairly constant orientation along the Lower Cretaceous interval. In this study the fractures are assumed to be formed under a single tectonic regime. However, when partitioning the fractures in different stratigraphic formations, a change in the direction of the fractures with depth is observed. This observation could be explained by the variation in rock's stiffness between different stratigraphic formations. Two techniques were used to model the subsurface fracture network: paleo-tectonic stress inversion and fracture network forward modelling techniques. The modelled DFN resembles the fractures geometry at the well location whereas away from the well the model is constrained by the subsurface fault geometry and far-field tectonic stress. Moreover, the modelled DFN consists of multiple 2 meters thick layers where each layer include a layer-bound fracture network. One of the main limitations of this approach is that it can not consider multiple tectonic regimes to simulate the fracture network. In addition, this approach requires large computational power.

Society relies on large amounts of energy to progress and allow for a high standard of living. The recent severe climate changes require advanced technologies related to cleaner energy resources. One such technology beneficial for accelerating this current energy transition is geothermal energy. This type of energy is often found in fractured and karstified carbonate aquifers. Understanding the reservoir properties and reducing the risks of such subsurface-related activities is vital. This thesis attempts to understand the complex fractured carbonate reservoirs better and improve the numerical simulation capabilities toward large-scale uncertainty quantification.@en

Natural fractures in subsurface rocks are a source of heterogeneity that impacts flow and transport behaviour. The presence of fracture discontinuities needs to be modelled explicitly due to observed deviations from the continuum assumption of porous media. The departures are due to both individual properties (such as aperture, infill, and roughness) and global network properties (such as topological summary and length distribution). Understanding flow patterns due to effects of rock fractures networks is essential formany applications such as exploiting hydrocarbons, geothermal heat extraction, subsurface nuclear waste storage, and water aquifer development. Assessing the impact of fractures in modelling studies requires fracture network data which is difficult to sample from seismic data (due to image resolution issues) and borehole data (owing to sparse sampling). Outcrop analogue data provide a means to sample networkswhile honouring both spatial position and topological relationships.@en

Responsibly using the subsurface for geo-energy extraction or storage requires an accurate understanding of the static and dynamic behaviour of the targeted reservoirs. While mostly dependent on intrinsic rock properties (e.g. porosity and permeability), this behaviour is also believed to be significantly impacted by the presence of natural fractures. For example, depending on their opening, connectivity, intensity or cement infill, natural fractures can both channel or inhibit fluid flow, thereby causing significant local flow heterogeneities which can both increase or decrease geo-energy production values. Therefore, assessing the possible characteristics of natural fractures has become an integral component in complex reservoir studies. @en

In 2020, as the world Energy demand keeps on rising (International Energy Agency (IEA), 2019), and with the global climate warming a reality (The Organisation for Economic Co-operation and Development (OECD), 2020), reducing our societal impact on Earth is of utmost importance. Energy and Climate have always been intrinsically related. Therefore, solving the Energy-Climate problem is a challenge where not one but several solutions should come together. Part of this global solution is the potential of geothermal resources. Geothermal energy is a renewable energy resource which has large potential to reduce the dependency on fossil fuels. Within the several uses of geothermal resources, a promising technique is titled Enhanced Geothermal Systems. More than renewable, this method has the potential to be sustainable. EGS consists of an originally low permeability reservoir rock that is artificially enhanced. The enhancement can be achieved by different stimulation techniques, such as mechanical, chemical, thermal or a combination of all. This thesis focuses on the mechanical EGS stimulation, where opening of existing fractures and creation of new ones is achieved by injecting a pressurized fluid in the reservoir rock formation. Such a process results in propagating a hydraulic fracture. The complexity of the EGS technique stands in predicting the hydraulic fracture propagation phenomena. EGS research and development is part of the GEMex goals. The GEMex project is a collaboration between Mexican institutions and the European Commission, dedicated to the development of non-conventional geothermal techniques. The Acoculco geothermal field, located in Puebla, is foreseen as a potential EGS. Because this field has been explored with two geothermal wells, and because an analogue exhumed system is available nearby, in the LasMinas area, this systemconstitutes a great research site for developing knowledge on EGS. @en