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Prof. Tomislav Malvić
University of Zagreb - Faculty of Mining, Geology and Petroleum Engineering

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Research Keywords & Expertise

0 Croatia
0 Terminology
0 interpolation
0 GEOMATHEMATICS
0 regional geology

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Croatia
interpolation
GEOMATHEMATICS

Honors and Awards

Golden medal at the exhibition INOVA 2017 (the best scientific innovation)

For co-authoring of the work Calculation of thermal maturity of rocks in depth, the Northern Croatia

Croatian Association of Innovators


Publons - annual award for top 1 percent reviewers (in cross-field), 9/2018-9/2019

Publons (Clarivate Analytics)


Silver medal on Arca 2019 exhibition

Computer measurement and numerical calculation of the carbonate rocks thermal maturity, case study Brač-1 beta well (Authors: Tomislav Malvić, Kristina Andrić, Josipa Velić, Željko Andreić, Josipa Pavičić)

Union of Croatian innovators




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Short Biography

(9/1995): Graduated geology on the Faculty of Mining, Geology and Petroleum Engineering in Zagreb and started to work as researching and teaching assistant. (8/2002): Joined to Team for geological development in Development Department in INA-Naftaplin as the specialist for geostatistics. He was responsible for statistical, geostatistical and stochastical analyses applied on the oil and gas fields geological model (in development stage). From 8/2005 he was promoted in expert and from 2007 in advisor of director in Development Dept. with analyses of geomathematics applied on hydrocarbon reservoirs. Internal reviewer of studies on reserves. From 2007/2008 - visiting lecturer on the Faculty. In the 2009 - research associate. In the 2013 - higher researcher associate->senior researcher as well as Assoc. Prof. From 2016 - tenure track, and from 2018 as Full Professor. Publons annual award, numerous awards of the Croatian Geol. Soc., Croatian innovation exhibition, several recognitions.

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Conference
Zagreb
Date: 2 October 2020
Conference organizer :
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Tomislav Malvić
Project

Project Goal: Selection of algorithms for efficiently interpolation

Starting Date:17 July 2020

Current Stage: Ongoing

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Project

Project Goal: Lead the university team of geologists and mathematicians

Starting Date:01 September 2019

Current Stage: Finished

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Journal article
Published: 12 June 2021 in Energies
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Small possible hydrocarbon gas reservoirs were analysed in the Bjelovar Subdepression in Northern Croatia. This area includes the Neogene–Quaternary, mostly clastics, sequences, reaching 3000+ metres in the deepest part. The shallow south-eastern part of the Drava Depression contains a subdepression characterised with several, mostly small, discovered hydrocarbon fields, where the majority are located on the northern subdepression margin. The reason is the large distance from the main depressional migration pathways and main, deep, mature source rock depocenters. However, two promising unconventional targets were discovered inside the subdepression and both were proven by drilling. The first are source rocks of Badenian, of kerogen type III in early catagenesis, where partially inefficient expulsion probably kept significant gas volumes trapped in the source rock during primary migration. Such structures are the Western Bjelovar (or Rovišće) and the Eastern Bjelovar (or Velika Ciglena) Synclines. The second promising unconventional reservoir consists of “tight” clastic lithofacies of mostly Lower Pontian located on the north-eastern margin of the subdepression. These are fine-grained sandstones with frequent alternations in siltites, silty and clayey sandstones. They are located on secondary migration pathways, but were never evaluated as regional reservoirs, although numerous drilling tests showed gas “pockets”.

ACS Style

Tomislav Malvić; Uroš Barudžija; Borivoje Pašić; Josip Ivšinović. Small Unconventional Hydrocarbon Gas Reservoirs as Challenging Energy Sources, Case Study from Northern Croatia. Energies 2021, 14, 3503 .

AMA Style

Tomislav Malvić, Uroš Barudžija, Borivoje Pašić, Josip Ivšinović. Small Unconventional Hydrocarbon Gas Reservoirs as Challenging Energy Sources, Case Study from Northern Croatia. Energies. 2021; 14 (12):3503.

Chicago/Turabian Style

Tomislav Malvić; Uroš Barudžija; Borivoje Pašić; Josip Ivšinović. 2021. "Small Unconventional Hydrocarbon Gas Reservoirs as Challenging Energy Sources, Case Study from Northern Croatia." Energies 14, no. 12: 3503.

Journal article
Published: 19 May 2021 in Hydrology
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Floods are defined by maximum water levels or flow of high-water waves. Here, we defined the deterministic method for the calculation of the probability of a high discharge event, named as the Probability Of Success (POS). The POS method previously developed for petroleum subsurface systems has been modified for the surface hydrological system with the purpose of flood prediction. The case study of this research is the small basin of Kašina Stream on Medvednica Mt. (NW Croatia). The data are obtained upstream from the hydrological station Gornja Kašina. The POS model is defined by four categories. Each geological category is described with accompanied events and probabilities. Floods are defined by four categories: total precipitation, total water flow, basement, and maximal water capacity in soil. The categories total precipitation and basement were divided into two sub-categories each: quantity and duration; porosity and soil depth. Data are collected for a hydrometeorological event, namely an intensive convective storm on 24–25 July 2020, when Zagreb was locally hit by heavy urban floods. The presented probability method yielded a probability of 1.76% that such an event could happen to the station. However, the flooding was not recorded. A comparison of the real event and the predicted probability supported the adequacy and applicability of the method, showing it has high reliability. The presented probability model could be easily applied, with small modifications, to the entire area of Northern Croatia for the prediction of small basin flooding events.

ACS Style

Vedran Sudar; Tomislav Malvić; Tatjana Vujnović; Josip Ivšinović. Modeling of the Geological Probability Procedure for the Prediction of High Flows in Small Streams, Case Study of Medvednica Mt., Croatia. Hydrology 2021, 8, 83 .

AMA Style

Vedran Sudar, Tomislav Malvić, Tatjana Vujnović, Josip Ivšinović. Modeling of the Geological Probability Procedure for the Prediction of High Flows in Small Streams, Case Study of Medvednica Mt., Croatia. Hydrology. 2021; 8 (2):83.

Chicago/Turabian Style

Vedran Sudar; Tomislav Malvić; Tatjana Vujnović; Josip Ivšinović. 2021. "Modeling of the Geological Probability Procedure for the Prediction of High Flows in Small Streams, Case Study of Medvednica Mt., Croatia." Hydrology 8, no. 2: 83.

Research article
Published: 05 February 2021 in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects
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Within the field of geological analysis of subsurface data, some input may be scarce and include a small set of data. Such a data set is under-sampled and mapping algorithms result in uncertain outcomes. It then becomes necessary to obtain a reliable statistical data set of individual geological variables. The possibility of applying the bootstrap method on variables that are relevant in the exploitation and production of hydrocarbons, specifically the porosity and total cost of disposal formation water variables, was analyzed. The case study was carried out on the data of reservoir “K”, field “B” located in the Western Sava Depression, Northern Croatia. The results highlight the appropriateness of applying the bootstrap method as a tool for defining uncertainty intervals on each sampled location. It is also dependent on resampling data set sizes, which is shown in three examples. The determination of uncertainty intervals for both studied variables gives crucial information for future development projects involving mature hydrocarbon reservoirs, and can be further applied in all similar Upper Miocene proven sandstone reservoirs in Northern Croatia. The porosity of the “K” reservoir is 0.2182 to 0.2506 at a resampling size of 2000, while the cost of disposal formation water value for field “B” is 2.31 to 2.69 USD/m3 at a resampling size of 1000.

ACS Style

Josip Ivšinović; Maria Alzira Pimenta Dinis; Tomislav Malvić; Dubravka Pleše. Application of the bootstrap method in low-sampled Upper Miocene sandstone hydrocarbon reservoirs: a case study. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects 2021, 1 -15.

AMA Style

Josip Ivšinović, Maria Alzira Pimenta Dinis, Tomislav Malvić, Dubravka Pleše. Application of the bootstrap method in low-sampled Upper Miocene sandstone hydrocarbon reservoirs: a case study. Energy Sources, Part A: Recovery, Utilization, and Environmental Effects. 2021; ():1-15.

Chicago/Turabian Style

Josip Ivšinović; Maria Alzira Pimenta Dinis; Tomislav Malvić; Dubravka Pleše. 2021. "Application of the bootstrap method in low-sampled Upper Miocene sandstone hydrocarbon reservoirs: a case study." Energy Sources, Part A: Recovery, Utilization, and Environmental Effects , no. : 1-15.

Preprint
Published: 06 November 2020
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In deep geological analysis of data, these are input data that are few and include a small set of data. In a small set of case data, it is necessary to obtain reliable data of individual geological variables from this type of data. The paper analyzes the possibility of applying the bootstrap method on variables that are important in the exploration and production of hydrocarbons. The variables analyzed were the following: porosity and total costs of disposal formation water. The case study was made on the data of reservoir "K", field "B" located in the western part of the Sava Depression. The analysis of the results showed the possibility of applying the bootstrap method in the analysis of deep geological data with the application of three different sizes of resampling dataset.

ACS Style

Josip Ivšinović; Tomislav Malvić; Dubravka Pleše. Application of the Bootstrap Method in Data Analysis of Upper Miocene Sandstone Reservoirs of the Western Part of the Sava Depression. 2020, 1 .

AMA Style

Josip Ivšinović, Tomislav Malvić, Dubravka Pleše. Application of the Bootstrap Method in Data Analysis of Upper Miocene Sandstone Reservoirs of the Western Part of the Sava Depression. . 2020; ():1.

Chicago/Turabian Style

Josip Ivšinović; Tomislav Malvić; Dubravka Pleše. 2020. "Application of the Bootstrap Method in Data Analysis of Upper Miocene Sandstone Reservoirs of the Western Part of the Sava Depression." , no. : 1.

Original paper
Published: 23 July 2020 in Arabian Journal of Geosciences
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Geological probability calculation was applied to the Northern Croatian Neogene deposits in the western Sava Depression. Structures “A” and “B” (with sandstone hydrocarbon reservoirs inside the Kloštar Ivanić Formation, Upper Miocene) were analyzed using two different Probability of Success (POS) methodologies. The classical POS approach showed that, in such play and wider areas of selected two structures, the probability for discovering the new HC reservoirs is 42.18%. This is valid for minimum of 500,000 m3 of geological reserves. The modified POS approach has been used for calculation of waterflooding efficiency in selected structures “A” and “B.” The probability value of 56.25% indicates that future flooding would result in increased recovery.

ACS Style

Josip Ivšinović; Tomislav Malvić; Josipa Velić; Jasenka Sremac. Geological Probability of Success (POS), case study in the Late Miocene structures of the western part of the Sava Depression, Croatia. Arabian Journal of Geosciences 2020, 13, 1 -12.

AMA Style

Josip Ivšinović, Tomislav Malvić, Josipa Velić, Jasenka Sremac. Geological Probability of Success (POS), case study in the Late Miocene structures of the western part of the Sava Depression, Croatia. Arabian Journal of Geosciences. 2020; 13 (15):1-12.

Chicago/Turabian Style

Josip Ivšinović; Tomislav Malvić; Josipa Velić; Jasenka Sremac. 2020. "Geological Probability of Success (POS), case study in the Late Miocene structures of the western part of the Sava Depression, Croatia." Arabian Journal of Geosciences 13, no. 15: 1-12.

Journal article
Published: 29 June 2020 in Processes
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The basic principles of geological risk calculation through probability of success (PoS) are mostly applied to numerical estimation of additional hydrocarbon existence in proven reservoirs or potential hydrocarbon discoveries in selected geological regional subsurface volumes. It can be adapted and validated for a comprehensive input dataset collected in the selected petroleum province, by dividing up geological events into several probability categories and classes. Such methodology has been widely developed in the last decades in the Croatian subsurface—mostly in the Croatian Pannonian Basin System (CPBS). Through the adaptation of geological categories, it was also applied in hybrid, i.e., stochastic, models developed in the CPBS (Drava Depression), mostly for inclusion of porosity values. As the robustness of this methodology is very high, it was also modified to estimate the influence of water-flooding in increasing oil recovery in some proven Neogene sandstone reservoirs in the CPBS (Sava Depression). This new modification is presented to be applied to geological risk calculation, intending to assess the safety of geological environment storage in deep wells, where spent nuclear fuel (SPN) would be disposed, a subject of great importance. The conceptual study encompassed the magmatic and metamorphic rocks in the pre-Neogene basement of the CPBS, intended to be used for such purpose. Regionally distributed lithologies are considered for nuclear waste disposal purpose, in order to detect the safest ones, considering petrophysical values, water saturation, recent weathering and tectonic activity.

ACS Style

Tomislav Malvić; Maria Alzira Pimenta Dinis; Josipa Velić; Jasenka Sremac; Josip Ivšinović; Marija Bošnjak; Uroš Barudžija; Želimir Veinović; Hélder Fernando Pedrosa E Sousa. Geological Risk Calculation through Probability of Success (PoS), Applied to Radioactive Waste Disposal in Deep Wells: A Conceptual Study in the Pre-Neogene Basement in the Northern Croatia. Processes 2020, 8, 755 .

AMA Style

Tomislav Malvić, Maria Alzira Pimenta Dinis, Josipa Velić, Jasenka Sremac, Josip Ivšinović, Marija Bošnjak, Uroš Barudžija, Želimir Veinović, Hélder Fernando Pedrosa E Sousa. Geological Risk Calculation through Probability of Success (PoS), Applied to Radioactive Waste Disposal in Deep Wells: A Conceptual Study in the Pre-Neogene Basement in the Northern Croatia. Processes. 2020; 8 (7):755.

Chicago/Turabian Style

Tomislav Malvić; Maria Alzira Pimenta Dinis; Josipa Velić; Jasenka Sremac; Josip Ivšinović; Marija Bošnjak; Uroš Barudžija; Želimir Veinović; Hélder Fernando Pedrosa E Sousa. 2020. "Geological Risk Calculation through Probability of Success (PoS), Applied to Radioactive Waste Disposal in Deep Wells: A Conceptual Study in the Pre-Neogene Basement in the Northern Croatia." Processes 8, no. 7: 755.

Preprint
Published: 26 May 2020
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The basic principles of geological risk calculation through Probability of Success (PoS) are mostly applied for numerical estimation of additional hydrocarbon existence in proven reservoirs or potential hydrocarbon discoveries in selected geological regional subsurface volume. It can be tailored and validated for a comprehensive input dataset collected in the selected petroleum province, adapted by dividing up geological events into several probability categories and classes. The most applied categories are (existence of) reservoir rocks, traps and isolators, source rocks, migration pathways and preservation conditions for hydrocarbons The methodology results in unique probability values as multiplication of independent statistical events, which can also be applied in the assessment of a potential hydrocarbon discovery of desired minimal volume and its value in any virtual currency like risk-neutral dollars. Such methodology has been extensively developed in the last decades in the Croatian subsurface, mostly in the Croatian part of the Pannonian Basin System (CPBS). Through the adaptation of geological categories, it was also applied in hybrid, i.e., stochastical, models developed in the CPBS (Drava Depression). Stochastically estimation of porosity was already applied. As the robustness of this methodology is very high, it was also modified to estimate the influence of water-flooding in increasing oil recovery in some proven Neogene sandstone reservoirs in the CPBS (Sava Depression). This new modification is being presented to be applied to geological risk calculation, intending to assess the safety of geological environment in deep wells, where depleted radioactive fuel would be disposed, a subject of great importance. The case study encompassed the magmatic and metamorphic rocks in the pre-Neogene basement of the CPBS. For disposal purpose, these are regionally lithologies considered as to be the safest ones considering petrophysical values, water saturation, recent weathering and tectonic activity.

ACS Style

Tomislav Malvić; Maria Alzira Pimenta Dinis; Josipa Velić; Jasenka Sremac; Josip Ivšinović; Marija Bošnjak; Uroš Barudžija; Želimir Veinović; Hélder Fernando Pedrosa E Sousa. Geological Risk Calculation through Probability of Success (PoS), Applied to Radioactive Waste Disposal in Deep Wells: A Case Study in the Pre-neogene Basement in the Northern Croatia. 2020, 1 .

AMA Style

Tomislav Malvić, Maria Alzira Pimenta Dinis, Josipa Velić, Jasenka Sremac, Josip Ivšinović, Marija Bošnjak, Uroš Barudžija, Želimir Veinović, Hélder Fernando Pedrosa E Sousa. Geological Risk Calculation through Probability of Success (PoS), Applied to Radioactive Waste Disposal in Deep Wells: A Case Study in the Pre-neogene Basement in the Northern Croatia. . 2020; ():1.

Chicago/Turabian Style

Tomislav Malvić; Maria Alzira Pimenta Dinis; Josipa Velić; Jasenka Sremac; Josip Ivšinović; Marija Bošnjak; Uroš Barudžija; Želimir Veinović; Hélder Fernando Pedrosa E Sousa. 2020. "Geological Risk Calculation through Probability of Success (PoS), Applied to Radioactive Waste Disposal in Deep Wells: A Case Study in the Pre-neogene Basement in the Northern Croatia." , no. : 1.

Journal article
Published: 15 May 2020 in Geosciences
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Geomathematics is extremely important in geosciences, particularly in the geology. The key for any geomathematical analysis is the definition of a typical model to be applied for further prognosis, either through deterministic or stochastic approaches. The selection of the appropriate procedure is presented in this paper. Two different geomathematical subfield datasets were used in subsurface geological mapping and palaeontology and different biostatistics applications, representing important geomathematical subfields in the Croatian geology. The different subsurface interpolation methods tested, validated and recommended for application were used to obtain the best possible outcome in reservoir modelling, in the cases with small datasets. Cross-validation may be chosen as the main selection criteria, applied to the Croatian part of the Pannonian Basin System (CPBS). Recent advances in biostatistics applied in palaeontology and case studies from Croatia are also presented, where biometric studies are of significant importance in fossil biota. Data, methods and problems in geosciences are vast subjects, and address a wide spectrum of fundamental science. Because geology includes subsurface and surface geology, and very different datasets regarding variable and number of data, we have chosen here two representative case study groups with original samples from Northern Croatia. Subsurface mapping has been presented on limited petrophysical datasets from the Northern Croatian, Miocene, hydrocarbon reservoirs. Biostatistics have been presented on very different samples, allowing us to achieve paleoenvironmental reconstructions of the size of relevant fossils, such as dinosaurs or other species and their paleoenvironments. All examples highlight examples of the valuable application of geomathematical tools in geology. The results, cautiously validated and correlated with other, non-numerical (indicator, categorical) geological knowledge, are of enormous assistance in creating better geological models.

ACS Style

Tomislav Malvić; Marija Bošnjak; Josipa Velić; Jasenka Sremac; Josip Ivšinović; Maria Alzira Pimenta Dinis; Uroš Barudžija. Recent Advances in Geomathematics in Croatia: Examples from Subsurface Geological Mapping and Biostatistics. Geosciences 2020, 10, 188 .

AMA Style

Tomislav Malvić, Marija Bošnjak, Josipa Velić, Jasenka Sremac, Josip Ivšinović, Maria Alzira Pimenta Dinis, Uroš Barudžija. Recent Advances in Geomathematics in Croatia: Examples from Subsurface Geological Mapping and Biostatistics. Geosciences. 2020; 10 (5):188.

Chicago/Turabian Style

Tomislav Malvić; Marija Bošnjak; Josipa Velić; Jasenka Sremac; Josip Ivšinović; Maria Alzira Pimenta Dinis; Uroš Barudžija. 2020. "Recent Advances in Geomathematics in Croatia: Examples from Subsurface Geological Mapping and Biostatistics." Geosciences 10, no. 5: 188.

Preprint
Published: 27 April 2020
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Geomathematics is extremely important in geosciences, particularly in the geology. The key for any geomathematical analysis is the definition of a typical model to be applied for further prognosis, either through deterministical or stochastical approaches. The selection of the appropriate procedure is presented in this paper. Two different geomathematical subfield datasets were used in subsurface geological mapping and palaeontology and different biostatistics applications, representing important geomathematical subfields in the Croatian geology. The different subsurface interpolation methods, tested, validated and recommended for application, were used to obtain the best possible outcome in reservoir modelling, in the cases with small datasets. Cross-validation may be selected as the main selection criteria, applied to the Croatian part of the Pannonian Basin System (abbr. CPBS). Recent advances in biostatistics applied in palaeontology and case studies from Croatia are also presented, where biometric studies are of significant importance in fossil biota. Data, methods and problems in geosciences is a vast subject, and address a wide spectrum of fundamental science. Because geology includes subsurface and surface geology, and very different datasets regarding variable and number of data, here are chosen two representative case study groups with original samples from Northern Croatia. Subsurface mapping has been presented on limited petrophysical datasets from the Northern Croatian, Miocene, hydrocarbon reservoirs. Biostatistics has been presented on very different samples, allowing to achieve paleoenvironmental reconstructions of size of relevant fossils, as dinosaurs or other species and their paleoenvironments. All examples highlight examples of the valuable application of geomathematical tools in geology. The results, cautiously validated and correlated with other, non-numerical (indicator, categorical) geological knowledge, are of enormous assistance in creating better geological models.

ACS Style

Tomislav Malvić; Marija Bošnjak; Josipa Velić; Jasenka Sremac; Josip Ivšinović; Maria Alzira Pimenta Dinis; Uroš Barudžija. Recent Advances in Geomathematics: Croatian Examples from Subsurface Geological Mapping and Biostatistics. 2020, 1 .

AMA Style

Tomislav Malvić, Marija Bošnjak, Josipa Velić, Jasenka Sremac, Josip Ivšinović, Maria Alzira Pimenta Dinis, Uroš Barudžija. Recent Advances in Geomathematics: Croatian Examples from Subsurface Geological Mapping and Biostatistics. . 2020; ():1.

Chicago/Turabian Style

Tomislav Malvić; Marija Bošnjak; Josipa Velić; Jasenka Sremac; Josip Ivšinović; Maria Alzira Pimenta Dinis; Uroš Barudžija. 2020. "Recent Advances in Geomathematics: Croatian Examples from Subsurface Geological Mapping and Biostatistics." , no. : 1.

Journal article
Published: 23 March 2020 in Stats
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Interpolation is a procedure that depends on the spatial and/or statistical properties of the analysed variable(s). It is a particularly challenging task for small datasets, such as in those with less than 20 points of data. This problem is common in subsurface geological mapping, i.e., in cases where the data is taken solely from wells. Successful solutions of such mapping problems depend on interpolation methods designed primarily for small datasets and the datasets themselves. Here, we compare two methods, Inverse Distance Weighting and the Modified Shepard’s Method, and apply them to three variables (porosity, permeability, and thickness) measured in the Neogene sandstone hydrocarbon reservoirs (northern Croatia). The results show that cross-validation itself will not provide appropriate map selection, but, in combination with geometrical features, it can help experts eliminate the solutions with low-probable structures/shapes. The Golden Software licensed program Surfer 15 was used for the interpolations in this study.

ACS Style

Tomislav Malvić; Josip Ivšinović; Josipa Velić; Jasenka Sremac; Uroš Barudžija. Application of the Modified Shepard’s Method (MSM): A Case Study with the Interpolation of Neogene Reservoir Variables in Northern Croatia. Stats 2020, 3, 68 -83.

AMA Style

Tomislav Malvić, Josip Ivšinović, Josipa Velić, Jasenka Sremac, Uroš Barudžija. Application of the Modified Shepard’s Method (MSM): A Case Study with the Interpolation of Neogene Reservoir Variables in Northern Croatia. Stats. 2020; 3 (1):68-83.

Chicago/Turabian Style

Tomislav Malvić; Josip Ivšinović; Josipa Velić; Jasenka Sremac; Uroš Barudžija. 2020. "Application of the Modified Shepard’s Method (MSM): A Case Study with the Interpolation of Neogene Reservoir Variables in Northern Croatia." Stats 3, no. 1: 68-83.

Journal article
Published: 29 February 2020 in Geosciences
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Morphometric analysis of Holocene pebbles from Sava River gravel in NW Croatia revealed shape distributions as observed along a 30 km long watercourse. Limestones, dolomites, and sandstones were identified as the major (>4%) and effusive magmatics in this alluvial aquifer system in Zagreb, with cherts and tuffs as minor pebble lithologies (up to 4%). Their distributions mainly indicate distant Alpine provenance for carbonate pebbles (limestone and dolomite) and local input for sandstones and minor lithotypes, laterally from the Samoborska Gora and Medvednica mountain. Carbonates are predominantly disc- and sphere-shaped, implying distant sources. Scattered distributions of pebble shapes (sphere, disc, blade, and rod) for sandstones and minor lithotypes possibly indicate multiple sources, some of them probably local. The tentatively interpreted “original sedimentary environments” for the main pebble lithotypes (calculated from their flatness ratios) possibly indicate that they are predominantly lake beach pebbles, followed by moraine and riverbed pebbles. However, these results should be strongly questioned.

ACS Style

Uroš Barudžija; Josipa Velić; Tomislav Malvić; Neven Trenc; Nikolina Matovinović Božinović. Morphometric Characteristics, Shapes and Provenance of Holocene Pebbles from the Sava River Gravels (Zagreb, Croatia). Geosciences 2020, 10, 92 .

AMA Style

Uroš Barudžija, Josipa Velić, Tomislav Malvić, Neven Trenc, Nikolina Matovinović Božinović. Morphometric Characteristics, Shapes and Provenance of Holocene Pebbles from the Sava River Gravels (Zagreb, Croatia). Geosciences. 2020; 10 (3):92.

Chicago/Turabian Style

Uroš Barudžija; Josipa Velić; Tomislav Malvić; Neven Trenc; Nikolina Matovinović Božinović. 2020. "Morphometric Characteristics, Shapes and Provenance of Holocene Pebbles from the Sava River Gravels (Zagreb, Croatia)." Geosciences 10, no. 3: 92.

Preprint
Published: 30 January 2020
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Morphometric analysis of Holocene pebbles from the Sava River gravels, in Zagreb alluvial aquifer system (NW Croatia), revealed distribution of their shapes along 30 km long observed watercourse. Limestones, dolomites and sandstones are determined as major (> 4%), and effusive magmatics, cherts and tuffs as minor lithotypes of the pebbles (up to 4%). Their distributions indicate mainly distant Alpine provenance for carbonate (limestones and dolomites) pebbles and local input for sandstones and minor lithotypes, laterally from the Samoborska gora and Medvednica Mts. Carbonates have predominately disc and sphere shapes, implying also their mainly distant sources. Scattered distributions of pebble shapes (sphere, disc, blade and rod) for sandstones and minor lithotypes indicate multiple sources, some of them probably local. Original sedimentary environments for main pebble lithotypes are tentatively interpreted from their flatness ratios, indicating predominant lake shore environments, followed by moraine and riverbed.

ACS Style

Uroš Barudžija; Josipa Velić; Tomislav Malvić; Neven Trenc; Nikolina Matovinović Božinović. Morphometric Characteristics, Shapes and Provenance of Holocene Pebbles from the Sava River Gravels (Zagreb, Croatia). 2020, 1 .

AMA Style

Uroš Barudžija, Josipa Velić, Tomislav Malvić, Neven Trenc, Nikolina Matovinović Božinović. Morphometric Characteristics, Shapes and Provenance of Holocene Pebbles from the Sava River Gravels (Zagreb, Croatia). . 2020; ():1.

Chicago/Turabian Style

Uroš Barudžija; Josipa Velić; Tomislav Malvić; Neven Trenc; Nikolina Matovinović Božinović. 2020. "Morphometric Characteristics, Shapes and Provenance of Holocene Pebbles from the Sava River Gravels (Zagreb, Croatia)." , no. : 1.

Journal article
Published: 21 January 2020 in Sustainability
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The authors analyse the process of water re-injection in the hydrocarbon reservoirs/fields in the Upper Miocene sandstone reservoirs, located in the western part of the Sava Depression (Croatia). Namely, this is the “A” field with “L” reservoir that currently produces hydrocarbons using a secondary recovery method, i.e., water injection (in fact, re-injection of the field waters). Three regional reservoir variables were analysed: Porosity, permeability and injected water volumes. The quantity of data was small for porosity reservoir “L” and included 25 points; for permeability and injected volumes of water, 10 points each were measured. This study defined selection of mapping algorithms among methods designed for small datasets (fewer than 20 points). Namely, those are inverse distance weighting and nearest and natural neighbourhood. Results were tested using cross-validation and isoline shape recognition, and the inverse distance weighting method is described as the most appropriate approach for mapping permeability and injected volumes in reservoir “L”. Obtained maps made possible the application of the modified geological probability calculation as a tool for prediction of success for future injection (with probability of 0.56). Consequently, it was possible to plan future injection more efficiently, with smaller injected volumes and higher hydrocarbon recovery. Prevention of useless injection, decreasing number of injection wells, saving energy and funds invested in such processes lead to lower environmental impact during the hydrocarbon production.

ACS Style

Tomislav Malvić; Josip Ivšinović; Josipa Velić; Jasenka Sremac; Uroš Barudžija. Increasing Efficiency of Field Water Re-Injection during Water-Flooding in Mature Hydrocarbon Reservoirs: A Case Study from the Sava Depression, Northern Croatia. Sustainability 2020, 12, 786 .

AMA Style

Tomislav Malvić, Josip Ivšinović, Josipa Velić, Jasenka Sremac, Uroš Barudžija. Increasing Efficiency of Field Water Re-Injection during Water-Flooding in Mature Hydrocarbon Reservoirs: A Case Study from the Sava Depression, Northern Croatia. Sustainability. 2020; 12 (3):786.

Chicago/Turabian Style

Tomislav Malvić; Josip Ivšinović; Josipa Velić; Jasenka Sremac; Uroš Barudžija. 2020. "Increasing Efficiency of Field Water Re-Injection during Water-Flooding in Mature Hydrocarbon Reservoirs: A Case Study from the Sava Depression, Northern Croatia." Sustainability 12, no. 3: 786.

Journal article
Published: 01 January 2020 in Mining of Mineral Deposits
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ACS Style

Josip Ivšinović; Tomislav Malvić. Application of the Radial Basis Function interpolation method in selected reservoirs of the Croatian part of the Pannonian Basin System. Mining of Mineral Deposits 2020, 14, 37 -42.

AMA Style

Josip Ivšinović, Tomislav Malvić. Application of the Radial Basis Function interpolation method in selected reservoirs of the Croatian part of the Pannonian Basin System. Mining of Mineral Deposits. 2020; 14 (3):37-42.

Chicago/Turabian Style

Josip Ivšinović; Tomislav Malvić. 2020. "Application of the Radial Basis Function interpolation method in selected reservoirs of the Croatian part of the Pannonian Basin System." Mining of Mineral Deposits 14, no. 3: 37-42.

Preprint
Published: 10 December 2019
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Interpolation is procedure that depends on spatial and/or statistical properties of analysed variable(s). It is special challenging task for data that included low number of samples, like dataset with less than 20 data. This problem is especially emphasized in the subsurface geological mapping, i.e. in the cases where data are taken solely from wells. Successful solutions of such mapping problems ask for knowledge about interpolation methods designed primarily for small datasets and dataset itself. Here are compared two methods, namely Inverse Distance Weighting and Modified Shepard’s Method, applied for three variables (porosity, permeability, thickness) measured in the Neogene sandstone hydrocarbon reservoirs (Northern Croatia). The results showed that pure cross-validation is not enough condition for appropriate map selection, but also geometrical features need to be considered, for datasets with less than 20 points.

ACS Style

Tomislav Malvić; Josip Ivšinović; Josipa Velić; Jasenka Sremac; Uroš Barudžija. Application of Modified Shepard's Method (MSM) case study with interpolation of Neogene reservoirs variables in the Northern Croatia. 2019, 1 .

AMA Style

Tomislav Malvić, Josip Ivšinović, Josipa Velić, Jasenka Sremac, Uroš Barudžija. Application of Modified Shepard's Method (MSM) case study with interpolation of Neogene reservoirs variables in the Northern Croatia. . 2019; ():1.

Chicago/Turabian Style

Tomislav Malvić; Josip Ivšinović; Josipa Velić; Jasenka Sremac; Uroš Barudžija. 2019. "Application of Modified Shepard's Method (MSM) case study with interpolation of Neogene reservoirs variables in the Northern Croatia." , no. : 1.

Journal article
Published: 05 May 2019 in Geosciences
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The interpolation of small datasets is challenging problem regarding the selection of interpolation methods and type of datasets. Here, for such analysis, the analysed data was taken in two hydrocarbon fields (“A” and “B”), located in the western part of the Sava Depression (in Northern Croatia). The selected reservoirs “L” (in the “A” Field) and “K” (“B”) are of Lower Pontian (Upper Miocene) age and belong to the Kloštar-Ivanić Formation. Due to strong tectonics, there are numerous tectonic blocks, each sampled with only a few wells. We selected two variables for interpolation—reservoirs permeabilities and injected volumes of field water. The following interpolation methods are described, compared and applied: Nearest Neighbourhood, Natural Neighbour (for the first time in the Sava Depression) and Inverse Distance Weighting. The last one has been recommended as the most appropriate in this study. Also, the presented research can be repeated in similar clastic environments at the same level hydrocarbon of exploration.

ACS Style

Tomislav Malvić; Josip Ivšinović; Josipa Velić; Rajna Rajić. Interpolation of Small Datasets in the Sandstone Hydrocarbon Reservoirs, Case Study of the Sava Depression, Croatia. Geosciences 2019, 9, 201 .

AMA Style

Tomislav Malvić, Josip Ivšinović, Josipa Velić, Rajna Rajić. Interpolation of Small Datasets in the Sandstone Hydrocarbon Reservoirs, Case Study of the Sava Depression, Croatia. Geosciences. 2019; 9 (5):201.

Chicago/Turabian Style

Tomislav Malvić; Josip Ivšinović; Josipa Velić; Rajna Rajić. 2019. "Interpolation of Small Datasets in the Sandstone Hydrocarbon Reservoirs, Case Study of the Sava Depression, Croatia." Geosciences 9, no. 5: 201.

Journal article
Published: 11 January 2019 in Geosciences
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The semivariogram and the ordinary kriging analyses of porosity data from the Sava Depression (Northern Croatia), are presented relative to the Croatian part of the Pannonian Basin system. The data are taken from hydrocarbon reservoirs of the Lower Pontian (Upper Miocene) age, which belong to the Kloštar Ivanić Formation. The original datasets had been jack-knifed with the purpose of re-sampling and calculating the more reliable semivariograms. The results showed that such improvements can assist in the interpolation of more reliable maps. Both sets, made by the original and re-sampled data, need to be compared using geological recognition of isoline’s shapes (such as “bull-eye” or “butterfly” effects) as well as cross-validation results. This comparison made it possible to select the most appropriate porosity interpolation.

ACS Style

Tomislav Malvić; Josip Ivšinović; Josipa Velić; Rajna Rajić. Kriging with a Small Number of Data Points Supported by Jack-Knifing, a Case Study in the Sava Depression (Northern Croatia). Geosciences 2019, 9, 36 .

AMA Style

Tomislav Malvić, Josip Ivšinović, Josipa Velić, Rajna Rajić. Kriging with a Small Number of Data Points Supported by Jack-Knifing, a Case Study in the Sava Depression (Northern Croatia). Geosciences. 2019; 9 (1):36.

Chicago/Turabian Style

Tomislav Malvić; Josip Ivšinović; Josipa Velić; Rajna Rajić. 2019. "Kriging with a Small Number of Data Points Supported by Jack-Knifing, a Case Study in the Sava Depression (Northern Croatia)." Geosciences 9, no. 1: 36.