1,720,957 research outputs found
Doublet deployment strategies for geothermal Hot Sedimentary Aquifer exploitation: Application to the Lower Cretaceous Nieuwerkerk Formation in the West Netherlands Basin
No full textHuge amounts of heat are stored in sedimentary aquifers in the Dutch subsurface. The amount of heat would be sufficient to provide our national heat demand for decades without any greenhouse gas emissions. Exploitation of this type of resource started some 10 years ago in the Netherlands. In 2016, 16 geothermal doublet systems had been installed that produce geothermal heat, and each year 2 to 3 new systems are realised. A doublet system consists of a production well that extracts hot formation water from kilometer deep aquifers. After the heat is extracted from the water in heat exchangers, the cooled water is reinjected into the same aquifer at approximately 1 to 1.5 km distance from the production well. Most of the current Dutch doublet systems provide heat for the horticulture sector. These systems have an average net energy production of approximately 10 MWth and therefore hundreds of additional systems are required to significant amounts of our heat consumption with geothermal energy. This PhD thesis investigated doublet system design and deployment strategies to optimise exploitation and increase the possible number of doublet systems exploiting the same aquifer. Based on detailed geological models, subsurface flow simulations are used to evaluate parameters such as required injector-producer distance, the preferred orientation of a well pair with respect to geological trends and required doublet distance to avoid negative interference. Based on the results, regional doublet deployment strategies can be developed to make optimal use of geothermal heat from sedimentary resources
The influence of fluvial reservoir architecture on geothermal energy production in Hot Sedimentary Aquifers
No full textCurrently six geothermal doublets are realized in the WNB. Five of these doublets target the same Lower Cretaceous fluvial sandstone interval, the Nieuwerkerk Formation. About 40 exploration licences are granted. Many of them also have sandstones in the same fluvial interval, the Nieuwerkerk Formation as a target. To successfully and efficiently produce geothermal energy from this fluvial sandstone interval, the distribution and internal architecture of the sandstone bodies must be better understood.Fluvial sandstone reservoirs are composed of stacked meander belts and floodplain fines. Net-to-gross, orientation and stacking pattern of the channel belts is of major importance for the connectivity between the injection and production wells in fluvial sandstone reservoirsApplied Geolog
Static reservoir architecture modelling of the TAGS, Algeria
No full textThis project investigated the occurrence of compartmentalization by claystone interbeds and its impact on connectivity in the fluvial units of the Triassic Argilo-Gréseux Supérieur (TAGS) formation in the Toual field, Algeria. The TAGS is located in a N-S oriented anticline, with faults part of a flower structure acting as hydrocarbon migration paths, and consists of two distinct formations based on facies. The fluvial TAGS Sandy, which consists of 4 different units, has compartmentalization in especially the meander deposited Sandy 2 and Sandy 4 units whilst Sandy 1 and 3, deposited coastal sabkha and by a braided river system respectively, show excellent connectivity. The coastal sabkha Upper TAGS, consisting of 7 units, shows excellent connectivity for Upper 1, 3, 5 and 7 in its sheet sands except for the deltaic deposited Upper 2 which is highly compartmentalized. The Upper 4 and 6 claystones might act as additional hydrocarbon seals to the overlying Liassic evaporites. A conceptual static reservoir model was created in Petrel to learn more about the size, shape and spatial distribution of the compartments. This was done by creating correlation panels parallel and perpendicular to the SW-NE orientation of the TAGS channel belt. Stratigraphic interpretation based on gamma ray, density and sonic logs as well as core photographs was used to divide the TAGS formation into separate units which were linked by reoccurring claystone intervals. This provided an insight into local fluvial channel belt shifts, mean sea level change and humidity levels. A 3D model was created of these units which was consequently used to estimate the Gas Initially In Place (GIIP) volume.Applied GeologyGeoscience & EngineeringCivil Engineering and Geoscience
Study of the Lower Cretaceous sands in the Van den Bosch Geothermal energy concession
No full textGoal of this project was to get a better understanding of the producing formations in the two doublets in the Van den Bosch Geothermal energy concession in Bleiswijk. It can be concluded based on the GR logs in VDB-04, the lithologs, End Of Well reports, a Biostrat log in VDB-04 and the seismic interpretation that the first doublet (VDB-01 & VDB-02) produces from a combination of the Rijswijk Member and another aggradational stacked sand formation. The second doublet (VDB-03 & VDB-04) produces from the Delft Sandstone. It is expected that producer and injector in each doublet have good communication and interference between the doublets is absent because the reservoirs are separated by the Rodenrijs Shale and production pressures and rates are constant for years. A regional well log correlation based on Maximum Flooding Surfaces is carried out to put the interpretation of the reservoir sands into a regional context with the surrounding oil fields. Using seismic interpretation the thickness and lateral extension of the Rijswijk and Delft reservoirs is determined. With these interpretations a static model is built of the reservoirs of the two doublets. In the second part of the project, field data from the past four years of production is analysed. The data consists of production rates, pump pressures and a well test in VDB-01. Using a Monte Carlo simulation ranges of the average permeability are calculated. The ranges of the average permeability are 200-500 mD in the Rijswijk and 300-600 in the Delft Sandstone. The main uncertainties in these estimated ranges are the Flowing Bottom Hole Pressure (FBHP) calculations, the skin and the thickness of the formation. In a history match exercise, production is simulated in a Dynamic model in Eclipse 100. The tuning parameter is the average horizontal permeability. In addition the influence on the simulation results of the vertical permeability, the skin and the fluvial shape factors is investigated. Resulting ranges of the average horizontal permeability are similar to those calculated with the radial inflow Monte Carlo simulation: 100-300 mD for the Rijswijk and 300-400 mD for the Delft Sandstone. Simulations show that the vertical permeability has a large influence on the reservoir performance and is therefore an important uncertainty. An initial estimation of the Rijswijk kvertical is 70% of Khorizontal and 22/386*khorizontal in the Delft Sandstone. This is based on earlier studies. Especially in the Rijswijk situation, the estimate may be too large. If the vertical permeability decreases, the horizontal permeability should increase to compensate in the history match. In that case the average permeability range approaches the results from the radial inflow equation analysis more. The well test was plagued by wellbore effects and a too short build-up period. Therefore no reliable parameters could be derived and compared to the radial inflow analysis and history match results. However the analysis showed that a well performed well test could give insight in skin, average permeability and flow boundaries.Petroleum EngineeringGeoscience & EngineeringCivil Engineering and Geoscience
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Reservoir modelling of Lower Cretaceous West Netherland Basin aquifers for geothermal energy production
No full textReservoir EngineeringApplied Geolog
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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