Marko Cvetković

University of Zagreb Faculty of Mining Geology and Petroleum Engineering

In accordance with the Regulation on monitoring radiation levels in the environment (NN 40/2018) and data from the Action plan for radon for the period 2019-2024 (OG 118/2018), it is necessary to implement measures to protect workers in places where radon appears and to perform periodic measurements for worker protection. Measurements of radon conc...

The deep saline aquifer (DSA) Poljana in the Upper Pannonian Poljana Sandstones of Sava depression, the SW part of the Pannonian basin system, was identified as a potential CO2 storage object in previous works. Its boundaries have been redefined and its general model further developed, including the areal distribution of porosity based on analyses...

One of the most innovative and effective technologies developed in recent decades for reducing carbon dioxide emissions to the atmosphere is CCS (Carbon Capture & Storage). It consists of capture, transport and injection of CO 2 produced by energy production plants or other industries. The injection takes place in deep geological formations with th...

As natural gas reserves are generally decreasing there is a need to successfully characterize potential research objects using geophysical data. Presented is a study of amplitude vs. offset, attribute and artificial neural network analysis on a research area of a small gas field with one well with commercial accumulations and two wells with only ga...

Soil gas measurements of radon (222Rn), CO2, and hydrocarbon concentrations, as well as gamma-ray spectrometry, were conducted at two separate locations to estimate the measurement results for known locations of hydrocarbon accumulations in the subsurface and oil seepage on the surface. The aim of the study was to confirm the applicability of the m...

A small area covered by a seismic volume was selected for the analysis of using artificial neural networks for the purpose of lithology modelling in a stochastic approach to an otherwise deterministic method. Subsurface lithology was simplified to three categories (sandstone, marl and coal) in accordance with the general geological composition of t...

Every country with a history of petroleum exploration has acquired geological knowledge of its sedimentary basins and might therefore make use of a newly emerging resource-as there is the potential to decarbonise energy and industry sectors by geological storage of CO2. To reduce its greenhouse gas emissions and contribute to meeting the Paris agre...

Presented work focuses on the importance of unconformity that separates the Neogene infill from older Palaeozoic and Mesozoic rocks in the Croatian part of Pannonian Basin. Structure map of this horizon nearly represents the thickness map of the Neogene and Quaternary basin fill. Rock formations just below the unconformity are significantly weather...

The main source rock facies in the Croatian part of the Pannonian Basin belong to the Middle Miocene and lower part of the Upper Miocene. These rocks are mainly identified in deep exploration wells, whereas outcrops are rare. Here we report on three stratigraphically different source rock intervals, which were recently discovered at Dilj Mt on the...

Lithofacies definition in the subsurface is an important factor in modelling, regardless of the scale being on the reservoir or basin level. In areas with low exploration level, modelling of lithofacies distribution presents a complicated task as very few inputs are available. For this purpose, a case study in Požega Valley was selected with only o...

Nitrates present one of the most common groundwater contaminants in the world and one of the five major groups of contaminants in the study area. Gaussian simulation (GS) algorithm was used for determining the spatial distribution of average nitrate concentrations from 2010 to 2015 on 95 sampling points. Results indicate two main focus areas of nit...

Eastern part of the Drava Depression presents a relatively small part within the Croatian part of the Pannonian Basin. A confined part within the Eastern part of the Drava Depression with a working petroleum system but few hydrocarbon accumulations was selected for the evaluation of the remaining hydrocarbon potential. Four subsurface models were b...

The regular working method for well log correlation in the Neogene-Quaternary infill of the Croatian Pannonian Basin is based on visual identification of specific motifs that can be observed regionally through the sub-basins or depressions. This method is proven successful through exploration for petroleum accumulations in the aforementioned area b...

One of the initial steps for the building of a proper subsurface model for the basin analysis, after solving structural relations, is the determination of lithofacies distribution. This can be either performed as a general mixed lithology based on well log data from a large interval or with a properly-layered model. In the latter, a variogram analy...

Lithofacies definition in the subsurface is an important factor in modelling, regardless of the scale being on the reservoir or basin level. In areas with low exploration level, modelling of lithofacies distribution presents a complicated task as very few inputs are available. For this purpose, a case study in Požega Valley was selected with only o...

Well logs from selected well within the Sava Depression, Pannonian Basin were selected for testing the applicability of standard deviation curve trends as a general outliner for sedimentation trends, well log marker position and enhancing correlation possibility. These logs consisted of classic electric well log measurements which include self pote...

Exploration of the Croatian Northern Adriatic and Southern Dalmatia Pliocene, Pleistocene and Holocene deposits in (coastline) offshore had been is reviewed. It was way to describe existing lithostratigraphic units in Croatian the Po River sediments and to determine such units in the depositional area of the Neretva River. Both systems have been in...

A preliminary assessment of the capacity of regional geological storage in the western part of the Sava Depression was based on data obtained from several deep exploration wells. The Poljana Sandstones represent a regional deep sandstone body, in most parts saturated with water, with promising underground facilities for the storage of CO₂ in the st...

The volume calculation of geological structures is one of the primary goals of interest when dealing with exploration or production of oil and gas in general. Most of those calculations are done using advanced software packages but still the mathematical workflow (equations) has to be used and understood for the initial volume calculation process....

Bacterial methane is a dominant hydrocarbon component in the Northern Croatia’s Adriatic offshore proven hydrocarbon reservoirs. As onshore reserves are declining the potential of shallow gas accumulation, analogue to the Adriatic ones, are being tested. A part of the Lonja Formation (Pliocene Pleistocene and Holocene), the Ravneš Member (Early Pli...

Exploration of Pliocene, Pleistocene and Holocene deposits in of the Croatian Northern Adriatic and Southern Dalmatia (coastline) offshore is presented in this paper. It was a way to describe the existing lithostratigraphic units in Croatian Po River sediments and to determine such units in the depositional area of Neretva River. Both systems have...

The aim of research was the accurate digitalization and subsurface modelling of the legacy data, namely paper-based geological maps. The research area covers approximately 1053 km 2 and is located in the Croatian part of the Pannonian Basin System, the Sava Depression, i.e. in the region of the Stružec Oil Field. Data input for the structural analy...

Coastal parts of Croatia are dominated by the SW-verging Dinaric foldbelt, to the west and SW of which is the Adriatic Basin (the stable foreland). In both areas, the stratigraphic column is dominated by a thick carbonate succession ranging from Carboniferous to Miocene. Four megasequences have been identified: (i) a pre-platform succession ranging...

In the evaluation of the initial hydrocarbon prospectively of the entire Lonja Formation (approximate Pliocene, Pleistocene and Holocene sequence), the Lower Pliocene Ravneš Member was used as analogy. In this member we tested the possibility of the HC generation based on biogenic reactions. This member bears large volumes of coal and organic rich...

We present two examples of describing low permeability Neogene clastic lithofacies to outline unconventional hydrocarbon lithofacies. Both examples were selected from the Drava Depression, the largest macrostructure of the Pannonian Basin System located in Croatia. The first example is the Beničanci Field, the largest Croatian hydrocarbon reservoir...

An accurate time to depth conversion between seismic and well data (velocity modeling) is often a challenge in those hydrocarbon fields which were developed in the second part of the 20th century due to the quantity and quality of well logs. The problem is also apparent in the regional explorations where well data are scarce or spatially far apart....

Data from selected Lower Pontian sandstone reservoir in the Kloštar Field, situated in the Sava Depression (Northern Croatia), were used for mapping with Sequential Indicator Simulations rather than using a classical approach. Such approaches offer better insight in distribution of geological variables or zonal uncertainties in the cases with large...

Introduction E-log markers are by default derived from well logs. The oldest approach considers defining markers using only electric logs (E- logs) such as spontaneous potential (SP) and resistivity (R). The newer approaches for defining markers also rely on newer well logs such as gamma ray, compensated neutron and others. Those are all focused ma...

The lithostratigraphic division and correlation is one of the most common stratigraphic divisions. It is strictly connected with lithological content of the rocks or deposits. Sometimes lithostratigraphic units, especially in rank of formations and members, can be approximately correlated with particular chronostratigraphic units in range of stages...

Stratal dip and azimuth data from dipmeter logs recorded at wells in the western Drava Depression (northern Croatia) were analysed in order to assist with subsurface structural interpretations. The dipmeter data came from the Miocene Moslavacka gora, Ivanic-Grad and Kloštar Ivanic Formations at wells Virovitica-3, Rezovacke Krcevine-1 istok, Rezova...

The main hydrocarbon reservoirs in the Croatian part of Pannonian Basin (CPBS) are discovered in sandstones of Upper Pannonian and Lower Pontian (i.e. Upper Miocene) ages (1st reservoir lithofacies). The other two reservoir lithofacies are Badenian coarse-grained clastites (2nd lithofacies) and Pre-Neogene carbonates, magmatites and metamorphites (...

Successful artificial neural network analyses of the lithology data – prediction of either sandstones or shale were obtained. These were performed in the youngest (Pliocene, Pleistocene and Holocene) sediments in Sava Depression, Croatian part of the Pannonian Basin, and the input data was based on well log curves (spontaneous potential, shallow an...

Approximately 104 x 106 m3 of oil (39 fields), 6.93 x 106 m3 of condensate (11 fields), and 64.92 x 109 m3 of gas (52 fields), were recovered in the Croatian part of the Pannonian Basin System during 64 years of exploitation (1941– 2005). The production peak was attained between 1980–1989, when exploitation began in 12 new fi elds. Based on their c...

Successful artificial neural network analyses of the lithology data - prediction of either sandstones or shale were obtained. These were performed in the youngest (Pliocene, Pleistocene and Holocene) sediments in Sava Depression, Croatian part of the Pannonian Basin, and the input data was based on well log curves (spontaneous potential, shallow an...

The Kloštar Oil and Gas Field lies approximately 35 km east of Zagreb in the Sava Depression, near the SW margin of the Pannonian Basin. According to detailed palinspastic reconstruction, based on well log data, the Miocene de- posits are up to 1600 m thick and transgressive over Paleozoic magmatites and metamorphites. Oil reservoirs are within Mio...

Three examples of the use of neural networks in analyses of geologic data from hydrocarbon reservoirs are presented. All networks are trained with data originating from clastic reservoirs of Neogene age located in the Croatian part of the Pannonian Basin. Training always included similar reservoir variables, i.e. electric logs (resistivity, spontan...

Approximately 104 x 106 m3 of oil from 39 fields, 6.93 x 106 m3 of condensate (11 fields) and 64.92 x 109 m3 of gas (52 fields) were recovered in the Croatian part of the Pannonian basin during 63 years of exploitation (1941–2004). The total production peak was attained in 1980–1989, when exploitation began in 12 new fields. The longest production...

There is large set of hydrocarbon fields and reservoirs that had been geostatistically analysed in the Croatian part of Pannonian Basin, i.e. in the Sava or Drava Depressions. Analyses had been done by programs Variowin 2.21 TM (freeware), Landmark TM application RC 2 , Surfer 8.0 TM , 3DField TM , RC 2 and Petrel TM . In the western part of the Sa...

The Geomathematical Dictionary was published by the Croatian Geologi-cal Society in Zagreb in 2008. Its format is A5, it has 74 pages, ISBN 978-953-95130-4-5. T. Malvić, M. Cvetković and D. Balić processed 103 geomathematical terms in their terminological dictionary. The dictionary's language and idea are clear, and concepts and terms in alphabetic...

The Klostar oil field is situated in the northern part of the Sava Depression within the Croatian part of the Pannonian Basin. The major petroleum reserves are confined to Miocene sandstones that comprise two production units: the Lower Pontian I sandstone series and the Upper Pannonian II sandstone series. We used well logs from two wells through...

Approximately 110x106 m3 of oil (100x106 tons) had been recovered from 38 fields in the Croatian part of the Pannonian basin during more than 60 years of exploitation (1941-2003). Based on their cumulative production, number of reservoirs, average porosity and permeability, obtained recovery and depositional characteristics of reservoir rocks, the...