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

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.

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.

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.

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.