The Uppermost Ablasserdam Member and Delft Sandstone Member are of high interest for geothermal energy extraction. The stratigraphy, sedimentology, and depositional environment of these members have been studied by different researchers over time. However, due to the lack of physical and extensive logging data within the West Netherlands Basin, there is still uncertainty about their depositional environment and how these sandstone bodies are vertically and laterally connected. Without this data, determining the depositional environment is challenging, and so is developing an optimized reservoir model.

This study performs a sedimentological analysis on the core, sidewall cores, and plugs, together with an investigation of the wireline logs of the DEL-GT wells. The main goal behind this is to determine the different lithofacies types and facies associations and interpret this while considering the limitations of the available data.

The Uppermost Ablasserdam Member and Delft Sandstone Member show characteristics of a fluvio-deltaic system and is located in an upper to lower delta plain environment. With observed facies associations of multi-stacked fluvial to distributary channels, single fluvial channels, crevasse splays, levees, overbank fines, and paleosols. The wireline logs help determine the vertical distribution of the facies, which showed a trend and lateral heterogeneous distribution between the wells. Thus, I could not correlate the wells to each other due to the lack of clear markers and indications that certain sandbodies are connected. Hence, more research on this is needed.

The wireline logs did show a trend from more sand-prone deposits to more silt-prone deposits, which can be related to the the different allogenic and autogenic controls. The controls likely influencing the depositional patterns are the tectonic activity and eustatic sea level change. In combination with climate change affecting the sediment supply and discharge rate, which influences the autocyclic controls of the channels.

This study is based on physical data from the first 80m interval of the one dimension DEL-GT-01 and side wall cores from DEL-GT-02-S2 wells. This brings an uncertainty in determining the lithofacies types and facies associations. Broader research must be done not only on the lithofacies types and facies associations but also on the lateral and vertical distribution. This will help determine the determine the limits of the reservoir.

Moreover, this study brings attention to the importance of extensive core and wireline log data collection.This data will reduce uncertainty for the reservoir model and increase the efficiency of the project and other future projects. It is also highly advised that all the findings and data should be open and free to use for future projects to reduce the uncertainties within the reservoir model.

Alluvial deposits in the subsurface are essential for geo-energy production and storage in many regions worldwide. Accurate correlation and characterisation of alluvial stratigraphy requires an understanding of how river channels were spatially deposited, and which geomorphological processes acted upon them. This doctoral dissertation the potential of orbital forced cyclic climate control on fluvial systems and its application to reservoir characterisation and subsurface correlation. It discusses the correlation between cyclic arrangements of floodplain strata and corresponding sandstone occurrence based on an analogue outcrop study. Subsequently the methods and concepts are applied on two subsurface case studies where correlation and characterisation of the reservoir is attempted. @en

High-level waste can be radiotoxic for thousands of years and should be carefully handled to prevent accidents. The research for geological disposal of radioactive waste focuses on the construction and durability of a geologic disposal facility in Dutch clays or salts. One of the challenges is assessing these host rocks’ capability to retard radionuclides and prevent them from entering the biosphere. This research focuses on disposal in clay. Because of clay’s low permeability, water movements are slow, and radionuclides transport is expected to occur predominantly by diffusion. The Peize and Waalre formations, situated on the interface between brackish and salt groundwater, serve as a natural analogue for targeted deeper, poorly indurated host rocks. The known disparity in chlorine levels between the aquifers adjacent to these clays qualify these formations for NaCl-tracer research. A cutting sampling study determined the conductivity of these clays’ porewater. Combining this with a one-dimensional modelling study, the saline history of this formation has been simulated. NaCl gradients were demonstrated at different drilling locations. The most manifested gradient is attempted to fit in the one-dimensional model. The model results suggest that this gradient originates from adjacent aquifer salinity, the clays’ physical properties and the difference in hydraulic head. The observed salinity discrepancy between aquifers and ion concentration gradient in the firstWaalre Clay confirm the assumption that the member can be a natural analogue. Uncertainty on the continuity of the total system prohibits concluding that diffusion-dominated transport in Dutch poorly indurated clays can be assumed. The best fitting scenario this research found fitting the empirical Waalre clay salinity curve is combined transport by diffusion and advection. The finding of diffusion-advection transport implies that the Waalre clay shows more complexity than initially expected.

The upper Carboniferous in the southern North Sea, especially the Westphalian B and lower Westphalian C stage is characterized by the deposited cyclothems that are a series of coarsening-upward fluvial sediments cycles. These cyclothems are often coal-bearing and no more than 15 m. Studying the fluvial cyclicity has a good potential for improved stratigraphy because the cyclothems show cyclic signals and provide a possible way of high-resolution correlation. An integrated approach using multiple approaches to come to a solid outcome also enables improving the stratigraphy. The previous studies mainly focused on large-scale stratigraphy with a vertical resolution of a few hundred meters. This study has analyzed the fluvial cyclicity and constructed an improved stratigraphic framework of Westphalian B and lower Westphalian C to better understand the sedimentary system. An integrated approach including lithostratigraphy, biostratigraphy and Integrated Predictive Error Filter Analysis (INPEFA) is applied to the series. Six intermediate-scale biozones with a thickness of tens of meters to around 150 m are applied. Six intermediate-scale units named stratigraphic packages were recognized by INPEFA curves of the gamma-ray log. The correlations of the biozones and the stratigraphic packages are consistent with each other, and the offset between the boundaries of these two zonations is generally between 2-15 m. Individual intermediate-scale units have a highly variable thickness and the standard deviation of one unit can be up to 42 m. Constrained by the biozones and INPEFA stratigraphic packages, four main coal seams are correlated and their lateral extent can reach 15 km. The small-scale cyclothems that range from 7 to 15 m can be extracted by INPEFA of potassium content log, referring to the small-scale INPEFA cyclicity. The cyclothems and the corresponding INPEFA cycles are thicker and better developed in the southern area. The average thickness of small-scale cycles is 12 m and these cycles are related to obliquity with a duration of approximately 35 kyr. The duration of Westphalian B calculated by the number and the time span of obliquity-scale cycles is nearly 1.2 Myr. No long-period, 100 & 400 kyr eccentricity cycles were recognized in this study.

The use of wireline facies associations can alleviate core data shortage during facies prediction by providing a more extensive input dataset. Wintershall has assigned wireline facies associations directly on cored and un-cored wells in the Carboniferous of the Sothern North Sea. Conducting facies prediction using these wireline facies associations as an input can help with tapping into the remaining exploration and development potential of the area. However, the accuracy of this input must be evaluated using core data before machine learning algorithms are applied. This was quantified as 71% for 9 cored wells, where the background floodplain and braided channel facies had the highest accuracies of 88% and 81% respectively, and the mouth bars and marine shales facies could not be adequately validated due to their insufficient core sampling. Consequently, when using wireline facies associations for training facies prediction algorithms, this input’s intrinsic uncertainty should be accounted for while examining the outputs, especially for facies that are not sufficiently validated by cores. Applying facies prediction with Support Vector Machine (SVM), Multilayer Perceptron Neural Network (MLP) and Recurrent Neural Network (RNN), showed that RNN can achieve the highest overall accuracy of 80.9%, due to the highest F1 scores for braided channel (0.88), point bars (0.60) and coal (0.53). The class imbalance problem is apparent for this dataset where the majority classes of background floodplain, braided channel, point bar and coal, are more predicted than the minority classes of crevasse splay sands, mouth bars, and marine shale. Applying RNN on the Westphalian A, B and C separately served as a form of imbalance correcting technique that increased the F1 scores of underrepresented facies. Future work can further refine the results by exploring imbalance correcting techniques through under-sampling the background floodplain and over-sampling the crevasse splay, mouth bar and marine shale facies.

To produce accurate 3D fluvial architecture models, it is important to understand the influence of internally generated autogenic controls versus externally generated allogenic controls. When studying a fluvial system, autogenic controls such as river meandering and avulsions generally dominate over 103-104 years. Allogenic controls such as climate change and tectonics dominate more at time scales of 105-106 years. A dominant control is astronomical climate change that may produce cyclical fluvial sedimentary successions. The resulting alluvial architecture of autogenic and of allogenic forcing is highly different and it is expected to largely influence geothermal flow through fluvial reservoirs. The aim of this research is to depict the impact of allogenic (cyclical) versus autogenic (non-cyclical) fluvial sedimentation on geothermal flow. Process-imitating and stochastic based modelling software Flumy is used to generate fluvial facies models where either hypothetical cyclical forcing or hypothetical non-cyclical forcing was the dominant force. These models are subsequently tested for geothermal flow using DARTS (Delft Advanced Terra Simulator). We find that the Flumy numerical model can be used to produce hypothetical cyclical and hypothetical non-cyclical alluvial architecture. The main difference between the architectures is the shape of the sand bodies. The cyclical model has overall thicker, laterally wider sand bodies. The non-cyclical model has thinner, less wide, but more often connecting sand bodies. Geothermal flow modelling shows that matching N/G in the cyclical and non-cyclical model in the 20-40 % N/G range gives similar pressures at a constant, fixed water rate. This points to the hypothesis that, at comparable N/G, the well connectivity must also be similar. The non-cyclical model breakthrough times in the 20-30 % N/G range are generally equal or slower, compared to the cyclical model. This gives credence to the hypothesis that the cyclical model has overall equal or slower flow paths between the well connections in the geothermal doublet. The difference in flow path hypothesis can be properly tested through visualizing 3D streamlines and is a recommendation for the future.

The rising demand for clean energy has drawn the attention for more geological research to low enthalpy geothermal applications in the Netherlands. A multi-scale reservoir characterization is carried out with the aim to understand the geothermal reservoir potential of the Triassic Main Buntsandstein (RBM) in the Tilburg area. Seismic data, well logs and petrophysical data are used to evaluate the reservoir architecture, stratigraphy, and quality of the potential Main Buntsandstein geothermal aquifer. It was found that the study area is located within a horst- and graben system bounded by normal faults where the top boundary of the RBM is located at depths of 1900 – 2100 m for the horsts and 3300 – 3500 m for the grabens. The horsts and grabens range from circa 3000 to 4000 meters in width. Well log correlations and thickness maps at RBM scale suggest thicknesses of the Subgroup from ca. 160 to 220 meter. The thickness of the Main Buntsandstein generally decreases on the horsts and increases towards the grabens, suggesting higher temperatures of up to 100° C and thicker sand units in the grabens. Thickness generally decreases on the horsts and increases towards the graben suggesting faults were active at time of deposition and better geothermal potential in the grabens due to greater depths and thicker RBM unit. The core analysis of the study showed that the potential Main Buntsandstein reservoir is composed of a variation of sand- and mudstones interlayers, which were deposited on a large fluvial-fan system terminating in a playa-lake environment towards the basin center. Four different facies associations were distinguished within the cores of wells AND-06, KWK-01, SPC-01 and WWN-01-S2. Optimal reservoir connectivity is, according to the facies architecture model, expected in the Lower Volpriehausen and Detfurth Sandstone Members due to the presence of stacked amalgamated fluvial fan sandstone facies. It appeared that aquifer quality does not correlate with increasing depth or stratigraphic position, although the Volpriehausen- and Detfurth Claystone Members display significant poorer reservoir properties. These members, which can be correlated at well distance due to its widespread deposition as playa-lake sediments, are likely to act as a baffle to flow in the subsurface. Best reservoir potential, considering petrophysical measurements on porosity and permeability, is within the fluvial fan sandstones of all facies associations whereas the fine grained cross bedded sandstones show best reservoir quality of all encountered lithofacies. The data showed highly variable measurements where highest mean values for the porosity (11 %) and permeability (105 mD) are encountered in the Lower Detfurth Sandstone Member of well HVB-01. It turned out that northern located wells of Tilburg (AND-06, KWK-01, WWN-01-S2 and SPC-01) showed considerable poor reservoir potential with mean values of below 10% and 10 mD for the porosity and permeability. The southern wells, however, appear to have generally higher reservoir properties compared to the northern wells suggesting better geothermal potential in the area south of Tilburg.

In 1990, the 44/21a-6 well was drilled in the Southern North Sea. Core material was taken from the Westphalian A/B part of the core. Some of this core material was recently obtained by the TU Delft via the North Sea Core Initiative. Since the Westphalian A/B in the Pennine Basin is fluvio-deltaic in origin, it is highly variable both vertically and laterally. In this thesis we set out to develop a method to extrapolate facies found in the core material to recognize if these are
present in other locations in the well. This means that core material is correlated to the well log. This correlation is then extended over the rest of the well. Two investigation targets were chosen, the first facies is channel base facies, consisting of very coarse sandstone, the second a swamp facies. This firstly requires a detailed core log, and a short study of the well log data. The core log is interpreted in order to try to establish some form of elektrofacies. The well data is then formatted and different principal component analyses (PCA’s) are performed in order to differentiate the facies from their surroundings. For both analyses more than 90% of the variance was explained by the first two component axes, making them reliable. Both target facies require different data sets in order to distinguish them from their surroundings. The swamp facies
becomes easily visible from the third principal component axis, while the channel base sand is harder to differentiate, being recognizable from a point cloud in a principal component plot. In total 40 coals were found to be present over the researched well interval, starting underneath the Zechstein formation, from 12800 to 13800 ft. No other similar channel base coarse sands
were found over the interval apart from the one in the cored material. Overall, it seems that the basics for this method of detection and extrapolation is quite reliable and better than using the original log data, although it does need some further development and improvement.

Accurately predicting the subsurface architecture is essential in finding potential reservoirs for subsurface engineering purposes. The architecture of the deposits is determined by both autogenic (internal) and allogenic (external) controls on the fluvial system and its deposition of sediments. However, the extents to which each of the two controls have an influence and how they interact in fluvial systems, is not sufficiently known for predicting the architecture of the deposits. Allogenic astronomical cycles have a trend which can be extracted from the deposits, leaving autogenic variability. This thesis means to find the lateral and vertical persistency of externally-driven floodplain deposits and their relation to the fluvial sands. Photogrammetry panels of the Early Eocene Willwood Formation (Bighorn Basin, USA) have been interpreted, a formation in which previous studies have found a pattern matching precession, one of the astronomical cycles. The formation consists of two floodplain facies in successions, together with a sandstone channel facies. Previous researches focused on the floodplain successions stratigraphically and only limited on the sandstones; this thesis means to find the lateral and vertical persistency of the floodplain successions and how these sandstones relate to the successions. The two floodplain facies, overbank deposits and heterolitics, form successions with an average thickness of 6.9m and standard deviation of 1.3m, measured over a maximum distance of 3.0km parallel and 2.8km perpendicular to the paleoflow direction. The longer the distance along which the successions are measured, the larger the range and standard deviation of an individual succession is and the more the average thickness converges to the average thickness of 6.9m. The average thickness over the 28 successions indicates a cyclicity period of 20.9kyr, matching precession cyclicity. The sandstones are subdivided into two classes based on their thickness: minor and major. The minor sands are observed to occur in the heterolitics layer of the floodplain successions. The average major sandbody thickness is 14.0m with a standard deviation of 3.9m, based on 13 bodies. Though most being multistory, it is thicker than results from previous research in the area. Opposed to the minor sands, there is not sufficient data and information on the major sands to confirm a depositional model. For the floodplain successions steps have been made to predict their behavior; once there is sufficient data to determine the role of the sandstones, prediction of the full alluvial architecture is enabled.

The Paleocene-Eocene Thermal Maximum (PETM) was a time of relatively abrupt climate change with intensive atmospheric greenhouse warming of 5 - 8˚C and is regarded as quasi-analogous for the modern anthropogenically-induced global warming. It therefore attracted considerable attention from geologists over the last decades. The PETM occurred 56 million years ago and is characterized by a sharp negative δ13C isotope excursion which has been observed in terrestrial and marine sediment records the world over. The PETM global warming led to a significant alteration in regional climate and to an enhanced hydrologic cycle which triggered an increase in weathering and sediment discharge from catchments to basins.
The sedimentary, biotic, and climatic responses to the PETM have been studied intensely on the American and European continents. However, detailed analyses of the impact to the PETM on the Asian continent remain rare. Here, a detailed analysis of the sedimentary and climatic response to the PETM in the Hengyang Basin, Hunan Province, China, is presented. High-resolution isotope measurements of pedogenic carbonate nodules reveal the characteristic isotope excursion of the PETM and strongly improve the previous low-resolution isotope series. Pedogenic features and clay types of PETM floodplain deposits indicate oxic conditions and a climate with pronounced seasonality in which intensive dry periods alternated with wet seasons. Grain size analysis of the paleosols support the hypothesis of coarsening deposits as a response to the PETM even though the coarsening is not strongly pronounced. Sediment bypassing and a depleted regolith in coarse material is suggested as the main reasons for the only minor pronounced coarsening in the PETM units. A generalized PETM model, which was simulated in PaCMod, a spatially lumped numerical model developed at the University of Delft, Netherlands, predicts an increase in net precipitation and erosion in the catchment area during the PETM. As a result, the simulated water discharge increases and lead to increased bedload and suspend load transport within the river system. These modelled results are correlative with the geological findings in the Hengyang basin. The Chinese terrestrial PETM record studied here corroborates the global continental impact of the greenhouse warming event through a shift towards pronounced aridity alternating with intensified wet seasons resulting in an oxic floodplain environment with a minor coarsening in grain size.

Every year the second years of the bachelor Applied Earth Science have a geological fieldwork in Southern France. To supervise the students after a day in the field the idea is to collect a 3D model database of the outcrops in the field. This is done by photogrammetry and the open-source program MicMac.
In this report an acquisition protocol and an automatic method for processing the images is developed. Students only need to collect images of their outcrop (following the given acquisition method) and upload them to the server. Some test cases are tested in this report and these results are given. The written workflow works on most test cases, except test cases made with a drone. The problems which arose were the right scale of the 3D models and sparse data at the boundaries of the outcrops. Although the workflow works in most cases, there are several adjustments to do in the future, like to make it more robust, find a method to create the right scales and to display all 3D models in one map.

Growing interest has been expressed the last decades regarding the Late Cenozoic, gas-bearing sediments of Southern North Sea Basin. Comprising the shallow subsurface of the Dutch offshore sector, these sediments have
been deposited by Eridanos fluvio-deltaic system, draining the Fennoscandian and Baltic shield through the present Baltic Sea. Three successful producing fields - A12-FA (2007), F02a-B-Pliocene (2009) and B13-FA (2011)- and
five under development have triggered the conduction of several studies in the offshore area. However the deltaic environment has been characterized as highly complex owing to its influence by the onset of Northern Hemisphere
Glaciation and thus the processes that governed the system have not become entirely understood. Enhanced cooling followed by the waxing and waning of the glaciers during warmer periods had an immediate impact on sediment
supply, accommodation space and mineralogical input. Although the sediments have been studied in terms of chrono-biostratigraphy, no systematic investigation with respect to the three main aforementioned factors as well
as the regional sequence stratigraphy and its link to the reservoir deposits has been made up to date. Therefore, this study employed sequence stratigraphy as a method to examine Eridanos conditions of deposition, investigate the
interplay between accommodation space and sediment supply and explore the nature of the gas-bearing reservoir sediments. The adopted methodology is comprised of two basic pillars, observation and interpretation. The first
records as clearly as possible the observations arise from the sequence analysis while the second extracts the meaningful information and interprets it in terms of temporal and spatial concepts. Using 2D seismic and well log data the basic observations were the stratal terminations, stacking patterns, seismic facies and the shoreline trajectory.
Seismic and well log interpretation showed that the delta experienced multiple events of sea level fall which forced the shoreline to regress basinward and caused sediment erosion or non-deposition. These events are bounded
by nine time-significant surfaces of subaerial unconformities which constitute the depositional sequences. Normal regression comprised the dominant depositional trend, combined with aggrading-prograding patterns, leading to
characteristic alternations of highstand and lowstand system tracts. Three main depositional environments which correspond to open marine turbidites (submarine lobes), delta front and delta top were identified from well logs,
core descriptions and the seismic facies analysis. The study suggests that the shallow gas is located in the alternations of silty-sandstones and claystones of the delta plain which comprise the vertical stacking of parasequence
topsets within the highstand- lowstand system tracts. Reconstruction of the relative sea level changes and sedimentation rates was made based on a technique introduced by this study. It uses the average thickness of each seismic
unit in order to interpolate time between the three known absolute ages obtained by the literature. The graphs showed that the accommodation space was generated by a low rate of sea level rise while sedimentation rates were
increasing over time. However the scarcity of time constrains in combination with the uncertainty in the estimation of seismic volumes resulted in a low resolution outcome. A comparison between the findings of this study and
those of the existing literature was made. The overall depositional trends and conditions seem to be in accordance with the other surveys. Nonetheless the proposed interplay between accommodation and supply can be assigned as
local since the examined area is limited compare to areas studied in literature. Limitations are traced in the quality of the 2D seismic data hampering the observation regarding the relation between the reflectors and the surfaces.
Consequently, the study offers an insight into the conditions under which the gas-bearing deltaic sediments were deposited and tries to place them in the established sequence stratigraphic framework. Also it provides information
regarding the distribution of the deltaic environments and identification of the reservoir rocks within each setting. The resulting interpretation can be used for prediction of the reservoir formations since the genetically-related
packages where they were identified are distributed in a predictable manner within a sedimentary basin.

There is an increased need for modelling the Dutch overburden to improve the prediction of earthquakes and subsidence due to the extraction of hydrocarbons. Depending on the surface location, the subsidence model of the NAM can under or over predict the amount of subsidence by 4 to 5 cm. This is around 15 % of the current maximum subsidence of 30 cm. The underlying assumption of the NAM subsidence model is that the reservoir, and the overburden above it, behave the same and thus have the same elastic parameters. The purpose of this research is to obtain a better understanding of the role overburden heterogeneities play in man induced subsidence. The main research question is: To what extent do overburden heterogeneities affect subsidence caused by reservoir depletion? Followed by the hypothesis: The heterogeneities of the overburden affect subsidence and should therefore be incorporated.
The results show that modelling the overburden as multi-layered, rather than as one homogeneous layer, leads to a difference of 0.75 cm. This is greater than the measurement error of the InSAR data, which is used to determine the subsidence of the Groningen field, and is significant when compared to the current discrepancy of 4 to 5 cm. Elastic parameters have been calculated from acoustic well data for geological units around the Groningen area. The calculated values differ from the values used by the NAM. When the calculated values are used for the Upper North Sea and Lower North Sea groups, the difference with the reference model is up to 2 cm for a reservoir radius of 3 km and 0.87 cm for a Groningen scale reservoir. The results suggest that the heterogeneities of the overburden affect subsidence significantly enough to warrant further investigation. Due to the fact that the obtained results are for horizontal layers, there is much potential for more complex overburden geology e.g. salt structures and non-horizontal layers.