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Wykorzystanie wielowariantowych modelowań przestrzennych do szacowania zasobów perspektywicznych złóż niekonwencjonalnych w centralnej części basenu lubelskiego

Papiernik B., Zając J., Michna M., Ząbek G., Machowski G., Kosakowski P., Poprawa P., Górecki W.

Prace Naukowe Instytutu Nafty i Gazu

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2016

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nr 209 wyd. konferencyjne

93--96

PL

W centralnej części basenu lubelskiego opracowano trójwymiarowy model utworów syluru, ordowiku i kambru. Model strukturalny obejmuje kompleksy pridolu – ludlowu, wenloku, landoweru, aszgilu, karadoku, lanwirnu, arenigu, tremadoku oraz kambru. Model strukturalny dowiązano do 76 odwiertów, a do jego opracowania wykorzystano archiwalne mapy miąższości i strukturalne oraz interpretację sejsmiki. W przestrzeni 3D wymodelowano zmienność refleksyjności witrynitu, co pozwoliło określić zasięg strefy okna gazowego, kondensatowego i ropnego. Modele zawartości węgla organicznego – współczesnej i pierwotnej, gęstości RHOB, oraz potencjału generacyjnego wyrażonego jako indeks wodorowy HI, pozwoliły oszacować bazowy model zasobów perspektywicznych z wykorzystaniem zmodyfikowanej metody Schmokera.

EN

In the presented study of central part of Lublin Basin 2D seismic, well data, laboratory measurements, well logs and results of 1D modelling in BasinMod were used as quantitative input for further Petrel based 3D modeling and resources assessment. Structural framework of the model comprises 9 surfaces (from the top of Silurian to the top of Cambrian), adjusted to stratigraphy of 76 wells. Modeled parameters involve vitrinite reflectance (Ro), present and original TOC, shale and brittle minerals volumes, RockEval S1 + S2 and HI parameters, bulk density (RHOB), porosity (PHI) and water saturation model. Models are based on laboratory data and well logs interpretation in 15 wells. Using reflectivity model oil, liquid and gas windows were established, and applying modified Schmoker method equations preliminary resources assessment for each window was completed.

2

Petroleum processes in the Palaeozoic - Mesozoic strata of the Grobla-Limanowa area (basement of the Polish Carpathians)

Wróbel M., Kosakowski P., Więcław D.

Geology, Geophysics and Environment

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2016

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Vol. 42, no. 2

185--206

EN

The geochemical characteristics of the Palaeozoic and Mesozoic strata of the basement of the Carpathian Foredeep depicted the Devonian and Carboniferous source rocks as the best source for hydrocarbon generation. Moreover, the Outer Carpathian sequence was geochemically characterized and proved capable of generating hydrocarbons. The oil-source rocks’ correlations indicated that the source of the condensate accumulated in the Łąkta field, while oil in the Grobla field. Maturity modelling identified Devonian source rocks as they reached a late phase of the “oil window” and, locally, even the “gas window”. The Carboniferous source rock was mature enough to start the generation processes. The generation started in the late Carboniferous, both in the Upper Silesian and Małopolska blocks. The main phase of the petroleum processes took place in late Neogene. The expulsion was observed only in the Devonian source rocks, and vertical migration by fault system in both blocks resulted in oil and gas accumulation in the Upper Jurassic carbonates and Upper Cretaceous sandstones. The petroleum modelling indicated the Devonian source for oil and gas fields in the study area. However oil-source rock correlation also suggests the presence of the Carpathian flysch source for hydrocarbons accumulated in the Łąkta field.

3

Origin and migration of oil from the Ukrainian Outer Carpathians to their Mesozoic basement: a case of Lopushna traps

Radkovets N. Y., Kotarba M., Koltun Y., Kowalski A., Kosakowski P., Więclaw D.

Geological Quarterly

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2016

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Vol. 60, No. 1

133--148

EN

Lopushna oil field has been discovered in Mesozoic-Paleogene strata of the platform basement under the Ukrainian Outer (Flysch) Carpathians. Oils from two main accumulations, occurring in the Upper Cretaceous sandstone and Upper Jurassic limestone reservoirs, have been analysed in order to identify their origin and relation to the known petroleum systems in the region of the Outer Carpathians and the basement of the Carpathian Foredeep. Results of geochemical investigations of oils, including biomarker and isotopic data, show a good correlation with oils, accumulated in the Carpathian flysch strata. Oils are low-sulphur and did not undergo significant degradation. They were generated from Type II or II/III kerogen, deposited in anoxic environments in clastic sediments. Generation occurred at the peak of “oil window”, probably in the temperature range of 122 to 126oC. The presence of oleanane indicates the Cretaceous or younger source rocks. Good correlation on biomarker and isotopic data with the organic matter dispersed in Oligocene Menilite Beds, occurring at the top of the Carpathian flysch succession, allowed authors to identify them as source rocks for oils of the Lopushna field, which thus can be regarded as an oil family of the Outer Carpathians. The migration distance for both Lopushna oils and oils accumulated in the Carpathian flysch strata was similar. A number of sub-vertical dislocations, on which the subsided flysch strata occur at the same depth level with the Jurassic and Cretaceous rocks of the platform, can be assumed as possible migration pathways from the mature source rocks of the Oligocene Menilite Beds of Boryslav-Pokuttya, Skyba or Krosno units to the Lopushna type traps, which suggests the possibility of existence of other hydrocarbon accumulations of this type. The Lopushna field so far is unique containing this type of oil found in the basement of the Ukrainian Carpathian Foredeep.

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1D modelling of hydrocarbon generation and expulsion from Oligocene Menilite source rocks in the San and Stryi rivers region (Polish and Ukrainian Carpathians)

Kosakowski P.

Geological Quarterly

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2013

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Vol. 57, No. 2

307–-324

EN

Based on geochemical data of the Oligocene Menilite Shales in the Boryslav–Pokuttya, Skole (Skyba), Silesian (Krosno) and Dukla units in the Carpathians, between Krosno and Styi towns, 1D modelling of generation and expulsion processes of hydrocarbons has been carried out. These strata are characterized by mostly high organic matter content, the total organic carbon (TOC) content reaching up to 26 wt.%. The highest hydrocarbon potential was recorded in the Boryslav–Pokuttya and Skole units. Organic matter in the Skole (Skyba) Unit is immature; in turn, in the Boryslav–Pokuttya, Silesian (Krosno) and Dukla units it is mature enough for generating hydrocarbons. Results of the modelling reveal that during the deposition of flysch in all the above mentioned Outer Carpathian units the Menilite source rocks did not reach a level of thermal maturity high enough to generate hydrocarbons. Conditions of hydrocarbon generation were obtained in the thrusting stage of the Outer Carpathians. In general, the process of hydrocarbon generation began at depths of less than 2 km in the Polish part, and about 4 km in the Ukrainian part. The kerogen transformation level reached from 10% to to complete transformation as in the Suche Rzeki IG 1 well.The results of the modelling of hydrocarbon generation and expulsion from the source rocks of all the units reveal that the highest maturity and the highest generation potential were obtained by the Menilite Shales in the Silesian and Dukla units.

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Gas generation in Carboniferous source rocks of the Variscan foreland basin : implications for a charge history of Rotliegend deposits with natural gases

Botor D., Papiernik B., Maćkowski T., Reicher B., Kosakowski P., Machowski G., Górecki W.

Annales Societatis Geologorum Poloniae

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2013

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Vol. 83, No. 4

353--383

EN

Numerical modelling of the Carboniferous–Permian petroleum system in the Polish Basin was carried out using PetroMod software. The Carboniferous source rocks contain organic matter mostly of a humic nature (gas-prone Type III kerogen). Subordinately, only in the Lower Carboniferous deposits, kerogen of algal marine origin and mixed Type II/III kerogen occur. The quantity of dispersed organic matter is variable, but usually below 2% TOC. In the Carboniferous section, a progressive increase in the maturity of organic matter with depth was observed, from approximately 0.5% Rr at the top of the Westphalian in marginal parts of the Carboniferous basin to over 5.0% Rr at the bottom of the Lower Carboniferous in the eastern Fore-Sudetic Homocline. The thermo- genic generation of hydrocarbons continued from the late Westphalian (eastern Fore-Sudetic Homocline and partly Pomerania) throughout the Mesozoic, up to the Late Cretaceous. The advancement of this process is va- riable in different parts of the Carboniferous basin, reaching up to 100% of kerogen transformation in the zones of maximum maturity of organic matter. However, the most intensive periods of gas generation and migration were the Late Triassic and the Late Jurassic. The most prospective areas are located NE of Poznań–Kalisz line and SW of Poznań.

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Habitat and hydrocarbon potential of the Mesozoic strata in the Kraków–Rzeszów area (SE Poland)

Kosakowski P., Więcław D., Kotarba M. J., Kowalski A.

Geological Quarterly

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2012

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Vol. 56, No 1

139-152

EN

The Mesozoic strata in the southeastern Poland were geochemically characterized to determine their hydrocarbon potential on the basis of 483 core samples from 36 boreholes. The Lower and Middle Triassic, Middle and Upper Jurassic, and Lower and Upper Cretaceous turned out to be highly variable. Middle Jurassic rocks represent the highest geochemical quality. Their total organic carbon (TOC) contents range between 0.0 and 17.0 wt.%, with a median of 0.89 wt.%. The highest TOC was observed in the rocks of the Tarnawa 1 borehole. In the remaining boreholes analysed the organic carbon contents were much lower and usually did not exceed 1 wt.%. Gas-prone Type-III kerogen with an admixture of Type-II kerogen is present in the study area. The lowest TOC values were observed in the Cretaceous rocks, where median values were 0.05 wt.% and 0.04 wt.% for Upper Cretaceous and Lower Cretaceous strata respectively. Low TOC contents were also observed in the Lower Triassic and Upper Jurassic strata. Accordingly, those horizons could not be regarded as effective source rocks. The petroleum potential of these stratigraphic horizons is additionally significantly reduced by low maturity, below the threshold for the generation of hydrocarbons. The Mesozoic organic matter was found to be generally immature, i.e. below 0.5% of vitrinite reflectance.

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Reservoir properties of the Palaeozoic–Mesozoic sedimentary cover in the Kraków–Lubaczów area (SE Poland)

Kosakowski P., Leśniak G., Krawiec J.

Annales Societatis Geologorum Poloniae

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2012

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Vol. 82, No. 1

51-–64

EN

During the 50-year-long intense petroleum exploration of the Palaeozoic–Mesozoic basement of the Carpathian Foredeep, more than 20 oil and gas accumulations have been discovered. The basic and most important oil-bearing levels in the Mesozoic section are Oxfordian carbonates and Cenomanian sandstones. The Nosówka, Zalesie, Trzebownisko–Krasne, Cetynia, Uszkowce and Lachowice hydrocarbon accumulations and numerous hydrocarbon shows have been found in the Palaeozoic horizons. This paper is focused on evaluation of reservoir properties of the entire Palaeozoic–Mesozoic basement of the Carpathian Foredeep and marginal part of the Outer Carpathians for finding new reservoir horizons. 558 rock samples from 51 wells in the Kraków–Lubaczów area were analysed. The well log results from 20 wells were additionally used for the assessment of petrophysical properties. The results of porosimetry measurements and well logs varied in all discussed Palaeozoic and Meso- zoic basement horizons of the Carpathian Foredeep. The best reservoir properties were estimated within the Jurassic–Lower Cretaceous carbonate complex. Despite great variability, the carbonate rocks display highest average porosity and good permeability values. The variability of reservoir properties is mostly a result of the character of the reservoir-porous-fracture space. Good reservoir properties were also estimated for the Upper Cretaceous carbonate rocks. However, in most of the analysed wells the potential reservoirs were watered. The Palaeozoic complex displays weaker reservoir properties and they mainly refer only to the Devonian–Lower Carboniferous horizon. The Lower Palaeozoic rocks display weak reservoir properties. Their potential is additio- nally lowered by negligible range of occurrence and a small thickness. Generally, the gas- and oil-bearing pro- perties of the analysed zone can be attributed only to the Jurassic–Cretaceous reservoir horizons. The remaining horizons, especially the Upper Palaeozoic complex, are only supplement to the reservoir potential of the area.

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Petroleum processes in the Palaeozoic and Mesozoic strata between Tarnów and Rzeszów (SE Poland) : 2-D modelling approach

Wróbel M., Kosakowski P., Krzywiec P.

Annales Societatis Geologorum Poloniae

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2012

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Vol. 82, No. 1

81–-97

EN

Two-dimensional modelling of hydrocarbon generation, expulsion, migration and accumulation pro- cesses in SE Poland between Tarnów and Rzeszów was carried out for five source rock horizons, i.e. the Ordo- vician, Silurian, Middle Devonian–Lower Carboniferous carbonates, Lower Carboniferous clastics, and Middle Jurassic. Five cross-sections in the study area allowed the reconstruction of timing and range of petroleum processes. The best source rocks related to the Ordovician and Silurian shales and mudstones reached “oil window” maturity within the entire study area and locally also reached the “gas window”. Generation of hydro- carbons was observed from all five source rocks, but the Ordovician and Silurian source rocks generated two and three times more hydrocarbons than the Lower Carboniferous and Jurassic source rocks, respectively. Expulsion took place only in case of the Lower Palaeozoic source rocks, but the volume of expelled hydrocarbons differed across the area. Hydrocarbons migrated from the Ordovician and Silurian source rocks to the Upper Jurassic (carbonates) and Upper Cretaceous (sandstones) reservoirs or to the Upper Palaeozoic carbonates in connection with the emplacement of the Carpathian thrust belt during the Miocene. Faults formed main migration pathways and hydrocarbons accumulated in structural and stratigraphic traps, located in the vicinity of faults. In places, traps are associated with a deep Miocene erosion surface. The onset of hydrocarbon generation took place during the Neogene, mainly the Miocene, but in the north, generation and expulsion started earlier – at the end of the Mesozoic.

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Assessment of hydrocarbon potential of the Lower Palaeozoic strata in the Tarnogród–Stryi area (SE Poland and western Ukraine)

Więcław D., Kosakowski P., Kotarba M.J., Koltun Y. V., Kowalski A.

Annales Societatis Geologorum Poloniae

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2012

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Vol. 82, No. 1

65–-80

EN

Quantity, genetic type and maturity of organic matter dispersed in the Lower Palaeozoic sequence from the Lower Cambrian to Silurian strata of the Polish and Ukrainian parts of the Carpathian Foredeep basement in the Tarnogród–Stryi area were evaluated based on the results of geochemical analyses of 475 rock samples collected from 45 wells. The best source rocks were found in the Silurian strata where the present total organic carbon (TOC) content is up to 2.6 wt%. They occur in the vicinity of Wola Obszańska, where the median of the present and the initial total organic carbon (TOC) contents in the individual wells amount to 0.98 and 1.6 wt%, respectively. The Cambrian and Ordovician strata have a poorer hydrocarbon potential and their present TOC content never exceeds 1 wt%. In all of the investigated Lower Palaeozoic strata, organic matter is represented by the oil-prone Type-II kerogen deposited in anoxic or sub-oxic conditions. The maturity of source rocks ranges from early mature (the initial phase of the low-temperature thermogenic processes) in selected zones of the Silurian strata in the vicinity of Wola Obszańska, through the middle and the final phase of “oil window” in the Ordovician and Cambrian strata in the Polish part of the study area, to the overmature stage in the Ordovician strata in the south-eastern part of the study area (Ukraine).

10

Petroleum systems in the Palaeozoic–Mesozoic basement of the Polish and Ukrainian parts of the Carpathian Foredeep

Kotarba M. J., Więcław D., Kosakowski P., Wróbel M., Matyszkiewicz J., Buła Z., Krajewski M., Koltun Y. V., Tarkowski J.

Annales Societatis Geologorum Poloniae

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2011

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Vol. 81, No 3

487-522

EN

Comprehensive geochemical analyses (Rock-Eval pyrolysis, stable carbon isotopes, biomarkers and aromatic hydrocarbons and elemental composition of kerogen) provide an explanation of genetic relationships between dispersed organic matter in various source rock horizons of the Palaeozoic–Mesozoic basement in the Carpathian Foredeep and also the liquid (oils and condensates) and gaseous hydrocarbons accumulated in reservoirs in the area between Kraków and Ivano-Frankivs’k. The study region was divided into seven zones around oil, condensate and gas deposits for detailed determination of genetic oil – natural gas – source rock correlation. Based on source, reservoir, seal and overburden rocks, generation, expulsion, migration and accumulation of hydrocarbons and trap formation along with 1-D and 2-D modelling, two separated petroleum systems of the Palaeozoic–Mesozoic strata were established. One petroleum system occurs in the western part of the Małopolska Block, the second one in the eastern part of the Małopolska Block and western part of the Kokhanivka Zone (south-eastern Poland – western Ukraine). In addition, nine generation and expulsion areas were identified. The comparison of the two petroleum systems reveals that the western part of the Małopolska Block has considerably greater prospects for oil and gas exploration than the eastern part of the Małopolska Block and the western part of the Kokhanivka Zone.

11

Habitat and hydrocarbon potential of the Palaeozoic source rocks in the Kraków–Rzeszów area (SE Poland)

Więcław D., Kotarba M. J., Kowalski A., Kosakowski P.

Annales Societatis Geologorum Poloniae

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2011

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Vol. 81, No 3

375-394

EN

The quantity, genetic type and maturity of organic matter dispersed in Ordovician, Silurian, Devonian and Lower Carboniferous strata in the basement of the Carpathian Foredeep between Kraków and Rzeszów were determined based on the results of organic geochemical analyses of 600 rock samples collected from 44 wells. The best source rocks were found in the Silurian strata where the total organic carbon (TOC) content is up to 6.6 wt% and the median value equals ca. 1.5 wt%. The median values of the initial organic carbon contents in individual wells vary from 1.2 to 3.5 wt%. The Ordovician, Lower Devonian and clastic facies of the Lower Carboniferous strata can be considered as an additional source of hydrocarbons with the median TOC values of 0.27, 0.56 and 0.53 wt%, respectively. The Middle and Upper Devonian strata as well as the carbonate facies of the Lower Carboniferous strata have much lower quantities of organic carbon, although in these strata levels with elevated TOC contents were observed. In the Lower Palaeozoic and Lower Devonian strata, the oil-prone, low-sulphur Type II kerogen is present, whereas in the younger divisions presence of the gas-prone Type III kerogen is visible. In the Lower Carboniferous clastics gas-prone kerogen dominates. The Silurian and clastic facies of the Lower Carboniferous strata have been deposited in the normal marine conditions, whereas the Ordovician, Devonian and carbonate facies of the Lower Carboniferous strata usually experienced reducing conditions. The source rocks are mostly at the initial and middle phase of the low-temperature thermogenic processes. Locally, immature (in the Lower Carboniferous carbonates in the vicinity of Łąkta gas-condensate field) or late-mature (in the Middle and Upper Devonian strata in the area of Grobla–Pławowice oil field) source rocks were observed.

12

Evaluation of hydrocarbon potential of the autochthonous Miocene strata in the NW part of the Ukrainian Carpathian Foredeep

Kotarba M. J., Więcław D., Kosakowski P., Koltun Y. V., Kowalski A.

Annales Societatis Geologorum Poloniae

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2011

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Vol. 81, No 3

395-407

EN

The quantity, genetic type, maturity and hydrocarbon potential of dispersed organic matter were determined for the complete sequence of the autochthonous Miocene ranging from the Lower Badenian Sandy-Calcareous Series to the Lower Sarmatian Upper Dashava Formation of the Bilche-Volytsia Unit. Geochemical analyses were conducted on 78 core samples collected from 11 wells in the Ukrainian Carpathian Foredeep between the Ukrainian-Polish state border and the Stryi River. The most favourable source-rock parameters characterize the Upper Badenian Kosiv Formation where the highest TOC contents, from 0.44 to 2.01 wt% (median 0.76 wt%), were found. Only slightly lower values were obtained for the Lower and the Upper Dashava formations – from 0.01 to 1.45 wt% (median 0.72 wt%) and from 0.62 to 0.77 wt% (median 0.71 wt%), respectively. In the Lower Badenian Sandy-Calcareous Series, the Lower Badenian Baraniv beds, and the Upper Badenian Tyras Formation, the TOC content is lower and varies from 0.00 to 0.77 wt%. Immature type III (terrestrial) kerogen dominates the analysed sections of the Kosiv and Dashava formations. Marine organic matter was detected sporadically, and only in the Upper Badenian Kosiv Formation in the vicinity of Kokhanivka, and in the Upper Badenian Kosiv and Tyras formations.

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Burial and thermal history and hydrocarbon generation modelling of the Lower Palaeozoic source rocks in the Kraków–Rzeszów area (SE Poland)

Kosakowski P., Wróbel M.

Annales Societatis Geologorum Poloniae

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2011

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Vol. 81, No 3

459-471

EN

Burial history, thermal maturity and timing of hydrocarbon generation were modelled for the Ordovician and Silurian source rocks in the basement of the Carpathian Foredeep. 1-D modelling was carried out for wells located in the area between Kraków and Rzeszów cities (SE Poland). The following wells were modelled: Będzienica 2, Hermanowa 1, Nawsie 1, Nosówka 2 and 12, Pilzno 40, and Zawada 8K. The Ordovician and Silurian source rocks, containing oil-prone Type-II kerogen, are generally immature showing less than 0.5% reflectance of vitrinite-like macerals (Ro), in most of the Kraków–Rzeszów area and only in the eastern part the organic matter is early mature, reaching 0.7% equivalent Ro. The highest thermal maturity is found in the eastern part of the study area, near Rzeszów city, where the Lower Palaeozoic strata are buried to the greatest depth. Maturity modelling shows that the source rocks reached the initial phase of the “oil window” only in the eastern part of the area, whereas they are immature in the larger, western portion of the area. In addition, modelling indicates that the onset of petroleum generation started in the late Miocene, after the Outer Carpathian overthrust phase. The generation processes in the eastern part of the analysed area reached the main and late generation phase. The generated hydrocarbons were mostly expelled from the source rocks. In the western part of the study area the generation process has not been initialized.

14

1-D modelling of the hydrocarbon generation history of the Jurassic source rocks in the Tarnogród–Stryi area (SE Poland – western Ukraine)

Kosakowski P., Wróbel M., Koltun Y. V.

Annales Societatis Geologorum Poloniae

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2011

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Vol. 81, No 3

473-485

EN

Reconstruction of burial and thermal history was modelled for the Mesozoic strata in the basement of the Polish and Ukrainian parts of the Carpathian Foredeep and in the marginal part of the Outer Carpathians. The 1-D modelling was carried out in profiles of the wells located in the area between Tarnogród and Stryi towns. In the Polish part, the modelling were performed in the profiles of the Księżpol 15, Lubliniec 9, Markowice 2 and Opaka 1 wells, and in the Ukrainian part in the profiles of the Chornokuntsi 1, Korolyn 6, Mosty 2, Podiltsi 1 and Voloshcha 1 wells. The geochemical characteristics of the Mesozoic stratigraphical horizons revealed that the best features of source rocks were present in the Middle Jurassic strata in the Polish part of the study area and in the Middle and Upper Jurassic strata in the Ukrainian part. Within these strata, the horizons of source rocks were distinguished and their quantitative evaluations were characterized. For these horizons, reconstruction of processes for hydrocarbon generation and expulsion were performed. The source rocks in the Polish part reached maturity only in the initial phase of “oil window”. However, the maturity achieved towards the end of the Upper Jurassic was insufficient to exceed the 10% threshold of the transformation degree for hydrocarbon generation. Therefore, the amount of generated hydrocarbons was minimal. Slightly higher maturity of organic matter in the Ukrainian part resulted in exceeding the thresholds of kerogen transformation and the initiation of hydrocarbon generation and expulsion processes. The process began after the deposition of thicker Miocene formations and developed even up to the main phase of the "oil window". The amount of the generated hydrocarbons reached ca. 150 mg/g TOC with an insignificant volume of expulsion.

15

Potencjał naftowy utworów jurajskich podłoża Karpat i zapadliska przedkarpackiego w rejonie Lwów-Sambor-Stryj (SW Ukraina)

Więcław D., Kotarba M. J., Kosakowski P., Koltun Y. V., Dudok I.

Prace Naukowe Instytutu Nafty i Gazu

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2010

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nr 170 wyd. konferencyjne

669--673

PL

Geochemiczna charakterystyka macierzystości utworów jurajskich w ukraińskiej części mezozoicznego podłoża zapadliska przedkarpackiego została wykonana w oparciu o wyniki badań 182 próbek pobranych z profili 12 odwiertów. Najbogatsze w materię organiczną są utwory jury środkowej, gdzie mediana TOC wynosi 0,72% wag. Utwory jury górnej są znacznie uboższe w węgiel organiczny (mediana TOC wynosi 0,11% wag). Utwory jury dolnej są całkowicie płonne (TOC poniżej 0,2% wag.). Potencjał węglowodorowy utworów środkowo- i górnojurajskich jest generalnie niski i zwykle nie przekracza 1 mg HC/g skały. W utworach jury środkowej dominuje gazotwórczy kerogen III typu. W węglanach górnojurajskich obserwuje się lokalnie zwiększony udział ropotwórczego kerogenu II typu. Dojrzałość utworów jury środkowej odpowiada początkowej i środkowej fazie generowania węglowodorów termogenicznych w„oknie ropnym", a górnej jury — przejściu z fazy generowania węglowodorów mikrobialnych do fazy „okna ropnego".

EN

Geochemical source-rock characteristics of the Jurassic strata in the basement of the Ukrainian part of the Carpathian Foreland was based on Rock-Eval results of 182 samples collected from 12 wells. The richest in organic matter are the Middle Jurassic strata, where TOC median equals 0.72 wt%. The Upper Jurassic carbonates are much poorer in organic carbon (TOC median equals 0.11 wt%). The Lower Jurassic strata are totally barren (TOC below 0.2 wt%). The hydrocarbon potential of the Middle and Upper 7urassic strata is generally low and usually do not exceed 1 mg HC/g rock. In the Middle Jurassic strata gas-prone Type III kerogen dominate. In the Upper Jurassic carbonates locally increased share of the oil-prone Type II kerogen is observed. Maturity of the Middle Jurassic strata responds to the initial and middle phase of the "oil window", and the Upper Jurassic rocks — transition between microbial hydrocarbon generation phase and "oil window".

16

Hydrocarbon generation/expulsion modelling of the lower Paleozoic potential source rocks in the Gryfice and Kolobrzeg blocks (NW Poland)

Wróbel M., Kosakowski P., Poprawa P.

Geological Quarterly

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2010

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Vol. 54, No 2

183-196

EN

The lower Paleozoic source rocks in the offshore part of the Gryfice and Kolobrzeg blocks (NW Poland) were studied through geochemical data and numerical modelling. The geochemical study revealed a presence of effective source rocks in Caradocian strata, but with low hydrocarbon potential. The remaining lower Paleozoic source rock horizons were not documented by core samples. The timing of hydrocarbon generation and expulsion was modelled for the K1-1/86 and L2-1/87 boreholes located in the Gryfice and Kolobrzeg blocks, respectively. 1-D and 2-D modelling indicated that in the Kolobrzeg Block the onset of petroleum generation occurred at the end of the Silurian and the beginning of the Devonian. Source rocks in the Gryfice Block reached the early stage of oil generation at the beginning of the Permian and generation processes were completed by the end of the Triassic. Migration of hydrocarbons from source rocks began in the Carboniferous in both the Gryfice and Kolobrzeg blocks and lasted to the end of the Mesozoic. During hydrocarbon migration, an intensive dispersion process was observed, caused by leaking along the fault planes. The modelling revealed that hydrocarbons may have accumulated in Devonian reservoirs. The lack of any discovered accumulations could be the result of hydrocarbon dispersion caused by tectonic deformation and intense vertical fault block movements.

17

Hydrocarbon generation and expulsion modelling of the lower Paleozoic source rocks in the Polish part of the Baltic region

Wróbel M., Kosakowski P., Poprawa P.

Geological Quarterly

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2010

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Vol. 54, No 2

241-256

EN

The burial history, thermal maturity, and timing of hydrocarbon generation of four source rock successions were modelled: the Middle Cambrian, the Upper Cambrian-Tremadocian, the Upper Ordovician (Caradocian) and the lower Silurian (Llandovery and Wenlock). The 1-D modelling was carried out in profiles of eight boreholes throughout the western Baltic region. Four selected boreholes are located offshore: A8-1/83, A23-1/88, B6-1/82 and B4-2A/02, and four onshore: Bialogóra 3, Dbki 3, Leba 8 and arnowiec IG 1. The thermal maturity of source rocks is the highest in the deeper buried western part of the basin and decreases from the west to the east and north-east towards the basin margins. The lower Paleozoic source rocks contain oil-prone Type-II kerogen. The modelling indicated that the onset of petroleum generation from the lower Paleozoic source rocks occurred from the Early Devonian through the early Carboniferous period. The peak of hydrocarbon generation took place from the Late Devonian to the Tournaisian. The majority of hydrocarbons generated were expelled during the latest Early Devonian and Carboniferous, and oil has not been expelled from source rock only in the eastern offshore part of the basin.

18

Habitat and hydrocarbon potential of the lower Paleozoic source rocks in the Polish part of the Baltic region

Kowalski A., Więcław D., Grotek I., Kotarba M. J., Kosakowski P.

Geological Quarterly

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2010

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Vol. 54, No 2

159-182

EN

The quantity, genetic type and maturity of organic matter dispersed in the Lower Cambrian to the uppermost part of the Silurian (Pridoli) sequence of the Polish part of the Baltic region was determined based on the results of geochemical analyses of a total of 1377 rock samples collected from 38 onshore and offshore boreholes. The best source rocks were found in the Upper Cambrian-Tremadocian succession where present and initial total organic carbon (TOC) contents are up to ca. 18 and 20 wt.%, respectively. Caradocian (Ordovician) strata can be considered as an additional source of hydrocarbons. In the individual boreholes median present and initial TOC contents vary from 0.5 to 3.3 wt.% and from 1 to 6 wt.%, respectively. The Llandovery (Silurian) strata reveal moderate and locally high hydrocarbon potential of the source rocks. The present TOC content reaches locally 10 wt.% (usually 1-2 wt.%). Another source of hydrocarbons can be clayey intercalations within the Middle Cambrian strata. Their organic matter content rarely exceeds 1 wt.%, being often a result of advanced organic matter transformation. In all lower Paleozoic strata investigated from the Polish part of the Baltic region oil-prone, low-sulphur Type-II kerogen occurs, deposited in anoxic or sub-oxic conditions. The maturity of all source rocks changes from the initial phase of the low-temperature thermogenic processes in the northeastern part to the overmature stage in the southwestern part of the study area.

19

Burial and thermal history of the Polish part of the Baltic region

Wróbel M., Kosakowski P., Poprawa P.

Geological Quarterly

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2010

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Vol. 54, No 2

131-142

EN

The burial history and thermal evolution of the western part of the Baltic region was reconstructed by means of 1-D modelling for eight boreholes penetrating the lower Paleozoic succession. The Neoproterozoic rifting presumably caused elevation of heat flow, while Cambrian to Mid Ordovician post-rift thermal sag of the Baltica passive margin led to systematic decrease of heat flow with time. Development of the Late Ordovician to Silurian flexural foredeep of the Caledonide collision zone was associated with intensive subsidence, a high rate of sediment deposition and rapid burial of the Upper Cambrian and/or Tremadocian, Upper Ordovician and lower Silurian source rocks, presumably sufficient for the early stage of oil generation. After post-Caledonian Early Devonian uplift, the western Baltic region was subject to Early Devonian to early Carboniferous subsidence and deposition, leading to further burial of the source rocks. Together with elevated heat flow, characteristic of the Variscan broad foreland, this caused further source rocks maturation and hydrocarbon generation. Late- to post-Variscan uplift and erosion (late Carboniferous to late Permian) resulted in complete removal of the Middle Devonian to lower Carboniferous strata and development of the major regional unconformity. During late Permian to Cretaceous time the western part of the Baltic region constituted an eastern flank of the Polish Trough, with the main phases of subsidence and burial during late Permian-Early Triassic time, related to rifting in the Polish Trough, and during Late Cretaceous time, related to the compressional regime. Maturity profiles in boreholes from the vicinity of the studied boreholes indicate the presence of a late Mesozoic (Late Cretaceous?) positive thermal event, causing further maturation of the source rock.

20

2-D modelling of petroleum processes of the lower Paleozoic strata in the Polish part of the Baltic region

Wróbel M., Kosakowski P.

Geological Quarterly

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2010

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Vol. 54, No 2

257-266

EN

2-D modelling of hydrocarbon generation, expulsion, migration and accumulation processes was carried out for the four (Middle Cambrian, Upper Cambrian-Tremadocian, Caradocian and Llandovery) source rock horizons. The petroleum potential of these source rocks is different, the highest being observed in the Upper Cambrian-Tremadocian horizon and the lowest in the Middle Cambrian one. The maturity of organic matter within these source units increases from the north-east to the south-west of the Polish part of Baltic region. The petroleum generation from these source rocks was highest in the Darlowo and Slupsk blocks as well as in the onshore part of the Leba Block. Expulsion took place mainly from the Upper Cambrian-Tremadocian source rocks and these rocks sourced almost all hydrocarbons accumulated within the Middle Cambrian sandstone reservoirs. Migration of hydrocarbons proceeded along fault zones. Almost all petroleum processes in the study area took place between the end of the Pridoli and the end of the Carboniferous. Moreover, during the Permian and the Mesozoic, part of the hydrocarbons remigrated within the reservoir. This process changed the setting and the volume of hydrocarbon accumulations. It was caused by the tectonic rebuilding of the basin and, in most cases, it led to the modification of accumulation range or to the dispersion of hydrocarbons.