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1

Source rock geochemistry, petrography of reservoir horizons and origin of natural gas in the Devonian of the Lublin and Lviv basins (SE Poland and western Ukraine)

Radkovets N. Y., Kotarba M. J., Wójcik K.

Geological Quarterly

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2017

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Vol. 61, No. 3

569--589

EN

The Rock-Eval source rock characteristics, mineral composition and type-porosity of reservoir horizons, and origin of natural gas in the Devonian of the Lublin and Lviv basins are described. In the Lower Devonian, the TOC content ranges from 0.01 to 1.82 wt.% in the Lublin Basin, and from 0.01 to 0.45 wt.% in the Lviv Basin. Transformation of organic matter varies from immature in the Lochkovian (Lviv Basin) to mature and overmature in the Emsian (Lublin Basin). The organic matter contains mainly Type-II kerogen, and underwent primary and/or secondary oxidation processes. In the Middle Devonian, the TOC content varies from 0.00 to 1.63 wt.% in the Lublin Basin, and from 0.02 to 0.64 to 2.35 wt.% in the Lviv Basin. The organic matter contains mainly Type-II kerogen and is immature in the Givetian of the Lviv Basin and mature in the Eifelian of the Lviv Basin and in the Eifelian and Givetian in the Lublin Basin. In the Upper Devonian, the TOC content is from 0.02 to 2.62 wt.% in the Lublin Basin, and from 0.04 to 1.43 wt.% in the Lviv Basin. Type-II kerogen dominates in both basins. Organic matter is mature in the Upper Devonian in the Lublin Basin and in the Famennian of the Lviv Basin and overmature in the Frasnian of the Lviv Basin. The reservoir horizons in the Devonian of the Lublin and Lviv basins are developed in clastic, carbonate and sulphate rocks. Terrigenous rocks form several separate horizons in the Lower and Middle Devonian of the Lviv Basin, and in the Upper Devonian (Famennian) of the Lublin Basin. Their filtration properties relate to intergranular porosity, while the fracture space has subordinate significance. Carbonate rocks form thick saturated horizons in the Givetian in the Lviv Basin, and in the Eifelian, Givetian and Frasnian in the Lublin Basin. Their filtration properties are produced by fracture porosity. Sulphates and carbonate-sulphate rocks with fracture and cavern porosity play a role as reservoir horizons in the Middle Devonian of the Lublin Basin. The natural gas collected from the Upper Devonian of the Lublin Basin was generated mainly during low-temperature thermogenic processes, from Ordovician–Silurian Type-II kerogen. The gas from the Middle Devonian reservoirs of the Lviv Basin was produced from Ordovician–Silurian Type-II kerogen and partly from the Middle and Upper Devonian mixed Type-III/II kerogen with maturity from about 0.9 to 1.4%. Carbon dioxide was formed by both thermogenic and microbial processes. Molecular nitrogen was generated mainly through thermal transformation of organic matter and also from destruction of NH4-rich illite of the clayey facies of the Ordovician–Silurian strata.

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Genetic correlation of source rocks and natural gas in the Polish Outer Carpathians and Paleozoic–Mesozoic basement east of Kraków (southern Poland)

Kotarba M. J., Więcław D., Bilkiewicz E., Dziadzio P., Kowalski A.

Geological Quarterly

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2017

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Vol. 61, No. 4

795--824

EN

Natural gas-source rock correlations in the Polish Outer Carpathians and Paleozoic–Mesozoic basement in the Kraków–Brzesko–Nowy Sącz area (southern Poland) have been established. In the Dukla and Sub-Silesian units, mixed kerogen Type-II/III or III/II occurs. The organic matter is immature or low-mature. The Oligocene Menilite beds of the Silesian Unit are rich in TOC and contain gas-prone Type III kerogen of low maturity. In the Paleozoic–Mesozoic basement, the TOC content and residual hydrocarbon potential vary in the Middle and Upper Devonian strata, Mississippian carbonate and clastic facies and Middle Jurassic strata. The Paleozoic strata are capable of thermogenic hydrocarbon generation, while organic matter in the Middle Jurassic rocks is generally immature. Gaseous hydrocarbons accumulated both in the Silesian and Dukla units of the Polish Outer Carpathians and in the Mesozoic basement are genetically related to thermogenic and microbial processes. The Outer Carpathian natural gas was generated mainly from the Type-II/III kerogen of the Oligocene Menilite beds. The thermogenic gases from the Mesozoic basement were generated from Devonian and Mississippian (carbonate) Type-II and mixed II/III kerogens and probably from Silurian/Ordovician Type-II kerogen and Middle Jurassic Type-III/II kerogen occurring at more than 7 km depth. Microbial methane migrated into the Outer Carpathian flysch succession from the Miocene strata of the Carpathian Foredeep.

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Zależność między występowaniem minerałów kruszcowych a charakterystyką geochemiczną materii organicznej w łupku miedzionośnym obszaru złożowego KGHM Polska Miedź S.A.

Pieczonka J., Więcław D., Piestrzyński A., Kotarba M. J, Rożek R., Jedlecki R., Szarowski W., Włodarczyk M.

Biuletyn Państwowego Instytutu Geologicznego

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2017

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nr 468

9--27

PL

W pracy przedstawiono charakterystykę okruszcowania i materii organicznej, występujących w łupku miedzionośnym, w wybranych profilach w dowiązaniu do przestrzennego rozkładu mineralizacji kruszcowej oraz parametrów i wskaźników materii organicznej w łupku miedzionośnym obszaru złożowego KGHM Polska Miedź S.A. Próbki skał pobrano w polu górniczym Głogów Głęboki Przemysłowy (5 próbek), oraz w północnej części pola Sieroszowice (11 próbek). W obydwu lokalizacjach opróbowano strefy depresji, charakteryzujące się większą miąższością łupku oraz strefy skłonu elewacji z widocznym wyraźnie ścienieniem łupku i strefy elewacji, gdzie jego miąższość zwykle nie przekracza 0,1 m. Badaniami objęto poziom łupku miedzionośnego, gdyż w nim zachodzi najwięcej zmian oraz jego charakter decyduje o ilości i jakości okruszcowania, w dolnej i górnej części profili złoża. Stwierdzono istotne zależności występujące pomiędzy całkowitą zawartością węgla organicznego i wartościami wskaźników HI i HI/OI materii organicznej a ilością i jakością okruszcowania. Wskaźnik HI wyraźnie koreluje się z zawartością siarczków miedzi. Jednakże wartości HI poniżej 100 mogą wskazywać na jakościową zmianę okruszcowania, w kierunku siarczków z miedzią dwuwartościową np. kowelinu. Niskie wartości wskaźnika HI/OI odpowiadają próbkom pochodzącym ze strefy przejściowej, gdzie zawartość minerałów Cu jest zmienna.

EN

General characteristics of ore minerals and organic matter in selected areas of the KGHM PM S.A are discussed in the paper. For the study, 5 samples from the Industrial Głogów Głęboki field and 11 samples from the Sieroszowice mining field have been collected At both locations, sampling was carried out from three areas: (I) the depression zone characterized by a relatively high thickness of the Kupferschiefer, (II) the elevation slope with a pronounced decrease of thickness, and finally (III) from the elevation where the Kupferschiefer thickness usually does not exceed 0.1 m. Detailed studies have been carried out on samples from the Kupferchiefer, because this horizon heavily affects the quantity and quality of ore mineralization in other parts of the economic ore deposit. Important relationships between the TOC content, HI and HI/OI indices and the quantity and quality of minerals is discussed. The hydrogen index is well correlated with the quantity of copper sulphides; however, its values below 100 may show quality changes of copper sulphides from Cu+ to Cu2+ (covellite). A low value of the HI/OI index represents samples from the transition zone, were sulphide contents are variable.

4

Pochodzenie i zagrożenia siarkowodorem i wysokociśnieniowym gazem ziemnym w złożu kopalń rud miedzi Polkowice-Sieroszowice i Rudna – wstępne badania izotopowe i mineralogiczne

Kotarba M. J., Bilkiewicz E., Manecki M., Pawlik W., Ciesielczyk A., Selerowicz T.

Biuletyn Państwowego Instytutu Geologicznego

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2017

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nr 469

9--33

PL

Wyniki badań składu cząsteczkowego i izotopowego (13C/12C w CH4, C2H6, C3H8, iC4H10, nC4H10 i CO2, 2H/1H w CH4 i 15N/14N w N2) dwóch próbek gazu ziemnego występującego w utworach wapienia cechsztyńskiego (Ca1) kopalni Rudna porównano z gazem ziemnym akumulowanym w utworach karbonu, czerwonego spągowca i wapienia cechsztyńskiego (Ca1) monokliny przedsudeckiej oraz gazu wytworzonego podczas pirolizy wodnej z kopalnej materii organicznej utworów dolomitu głównego (Ca2). Badany gaz ziemny charakteryzuje się normalnym składem izotopowym w układzie metan–etan–propan, co świadczy o tym, że powstał w jednej fazie generowania z tej samej skały macierzystej, zawierającej kerogen mieszanego typu II/III, prawdopodobnie w obrębie utworów karbońskich. Na podstawie badań mineralogicznych i izotopowych 13C/12C 12 próbek węglanowych i 34S/35S 14 próbek siarczanowych, pobranych w strefie głębokości eksploatacji rud miedzi od 900 do ok. 1200 m ZG Polkowice-Sieroszowice i Rudna w zakresie współczesnych temperatur od 35 do 45°C, wykazano, że w dwóch próbkach węglanów i w dwóch próbkach siarczanów pobranych z jednego rdzenia zachodzą procesy mikrobialnej redukcji anhydrytu dolnego (Ad1) cyklu PZ1 prowadzące do powstawania siarkowodoru.

EN

Composition of natural gas from the Zechstein Limestone (Ca1) strata of Rudna mine has been compared with the natural gas from Carboniferous, Rotliegend strata of the Fore-Sudetic Monocline and with gas generated from the organic matter of the Main Dolomite during hydrous pyrolysis experiments. The gas from Rudna mine is characterized by the normal methane–ethane–propane isotopic system which indicates formation in one stage from a single source rock probably of the Carboniferous age containing kerogen of mixed II/III type. Generation of the hydrogen sulphide resulted from the microbial sulphate reduction processes of the basal anhydrite has been proven by mineralogical and isotopic 13C/12C analyses of 12 carbonate and 34S/35S analyses of 14 sulphate samples. These samples were collected in the mine at the depth of about 900–1200 m at temperature range of 35–45°C and two samples of carbonates were taken from one core.

5

Potencjał generowania ropy i gazu dolnopaleozoicznych formacji łupkowych w świetle badań pirolizy wodnej

Więcław D., Kotarba M. J., Romanowski T.

Prace Naukowe Instytutu Nafty i Gazu

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2016

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nr 209 wyd. konferencyjne

455--458

PL

W celu wyznaczenia potencjału generowania ropy i gazu utworów syluru i ordowiku bogatych w materię organiczną (potencjalne „sweet spoty”) wykonano eksperymenty pirolizy wodnej w temperaturach 330 i 355°C w czasie 72 godz. próbek pobranych z odwiertów: B3 (landower), L-3H (landower) i L-1 (karadok) w regionie pomorskim oraz w celach porównawczych z powierzchniowych odsłonięć utworów wenloku w wąwozie Prągowiec i landoweru we wsi Bardo w Górach Świętokrzyskich. Wykonano również eksperymenty w temperaturach 380 i 400°C w czasie 72 godz. próbek z odwiertów B-1 (landower i karadok) i W-1 (landower i karadok) (region pomorski). Najwyższym potencjałem ropotwórczym (do 217,4 mg ropy/g TOC) charakteryzuje się niskodojrzała materia organiczna rozproszona w utworach landoweru w profilu odwiertu B3. Najwyższą wydajność węglowodorów gazowych (56,7 mg HC/g TOC) uzyskano z próbki B-1 (landower) podczas eksperymentu prowadzonego w warunkach 400°C/72 h.

EN

For determination of oil and gas generation potential of organic-rich Silurian and Ordovician strata (potential „sweet spots”), series of hydrous pyrolysis experiments were performed at temperatures 330 and 355°C for 72 hours using core samples from: B3 (Llandovery), L-3H (Llandovery), L-1 (Caradocian) from Baltic region, and outcrop samples: Bardo (Llandovery), Prągowiec (Wenlock) in Holy Cross Mountains. High temperature experiments in 380 and 400°C for 72 hours were also performed using core samples from wells B-1 (Llandovery and Caradocian) and W-1 (Llandovery and Caradocian) containing high mature organic matter. The highest oil yield (217.4 mg/g TOC) was obtained from low-mature organic matter in B3 sample (Llandovery) in 355°C/72h. The highest gaseous hydrocarbons yield (56.7 mg HC/g TOC) was recorded for B-1 (Llandovery) sample in experiment conducted at 400°C/72 h.

6

Wyniki powierzchniowych badań geochemicznych w rejonie odwiertów ukierunkowanych na poszukiwanie i udostępnienie gazu ze złóż niekonwencjonalnych

Sechman H., Dzieniewicz M., Kotarba M. J., Guzy P., Konieczyńska M., Lipińska O.

Przegląd Górniczy

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2015

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T. 71, nr 10

68--80

PL

W przypadku poszukiwania i eksploatacji gazu ziemnego ze złóż niekonwencjonalnych kontrowersję budzi możliwość pojawienia się zagrożeń dla środowiska. Jednym z nich może być niekontrolowana migracja gazu (głównie metanu) do strefy przypowierzchniowej i atmosfery na skutek np. nieszczelności odwiertu. W ocenie szczelności odwiertów najskuteczniejsze są powierzchniowe metody geochemiczne realizowane w wariancie gazu wolnego. Generalnie polegają one na zassaniu z niewielkiej głębokości mieszaniny gazu wypełniającego wolne przestrzenie w środowisku skalnym i określeniu w nich stężeń metanu i jego lekkich homologów, gazowych alkenów i dwutlenku węgla. W wybranych próbkach o podwyższonych stężeniach węglowodorów i dwutlenku węgla określono również skład izotopowy. W artykule przedstawiono wyniki powierzchniowych badań geochemicznych na obszarze jednego z zakładów prowadzących roboty geologiczne polegające na poszukiwaniu i rozpoznawaniu niekonwencjonalnych złóż węglowodorów metodą otworową z zastosowaniem szczelinowania hydraulicznego. Wyniki wykonanych badań wykazały obecność anomalnych stężeń metanu i dwutlenku węgla, a także podwyższonych stężeń wyższych od metanu alkanów i alkenów gazowych. Maksymalne stężenia metanu, sumy alkanów C2-C5, sumy alkenów C2-C4 i dwutlenku węgla wynosiły odpowiednio: 35,4 % obj., 99,4 ppm, 1,2 ppm i 19,7 % obj. Wyniki badań izotopowych wykazały, że metan i dwutlenek węgla są głównie pochodzenia mikrobialnego. Powstały one współcześnie podczas fermentacji mikrobialnej. Badania te wykazały, że na pewno nie jest to gaz termogeniczny związany z utworami syluru. Procesy fermentacji mikrobialnej mogą być intensyfikowane pod geomembraną izolującą środowisko gruntowo-wodne od atmosfery. Poza efektami współczesnych procesów mikrobialnych, w rejonie badań zarejestrowano w powietrzu gruntowym także naturalne podwyższone mikrostężenia alkanów C2-C5 świadczące o przenikaniu odzłożowym, prawdopodobnie z pokładów węgla w utworach górnego karbonu. Obecność tych gazów w strefie przypowierzchniowej może być rezultatem naruszenia, w czasie wiercenia, ciągłości utworów zawierających naturalne nagromadzenia węglowodorów w utworach karbonu. Geomembrana zaś powoduje zatrzymywanie migrujących składników alkanowych doprowadzając w konsekwencji do wzrostu ich stężeń.

EN

The exploration for and production of natural gas from unconventional deposits raises many controversies concerning the environmental hazard. One of such threats can be an uncontrolled escape of gas (mostly methane) to the near-surface zone and to the atmosphere caused by e.g. leaking wells. In the evaluation of well tightness, the most effective are surface geochemical methods applying the free gas mode. The principle of these methods is the proper sampling of gases filling the open spaces in soils at shallow depths and determination of concentrations of methane and its gaseous homologues, gaseous alkenes and carbon dioxide. In samples showing increased concentrations of hydrocarbons and carbon dioxide, stable isotopes’ composition is analyzed, as well. The following paper presents the results of surface geochemical survey in the area where exploration for unconventional gas deposits is currently run with the fracking method. The results indicate the presence of anomalous concentrations of methane and carbon dioxide together with the increased contents of higher gaseous alkanes and alkenes. Maximum concentrations of the analyzed components are: methane – 35.4 vol.%, total alkanes C2-C5 – 99.4 ppm, total alkenes C2-C4 – 1.2 ppm and carbon dioxide – 19.7 vol.%. The results of stable isotope analyses reveal that methane and carbon dioxide were generated mostly during the recent microbial fermentation and preclude their thermogenic origin related to Silurian formations. Microbial fermentation can be intensified if it proceeds beneath a geomembrane, which isolates the soil and aquatic environment from the atmosphere. Apart from recent microbial reaction, the analyses indicate the increased microconcentrations of alkanes C2-C5, which documents the migration of gases from deep accumulations, presumably from coal seams hosted in Upper Carboniferous formations. The presence of these gases in the near-surface zone may result from the disruption of Carboniferous rocks hosting natural hydrocarbon accumulations during the drillings. The geomembrane restrains the migrating gaseous alkanes and raises their concentrations.

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Origin and maturity of oils in the Ukrainian Carpathians and their Mesozoic basement

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

Geological Quarterly

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2012

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Vol. 56, No 1

158-168

EN

Geochemical characteristics of 25 oils collected from Skiba Unit of the Outer Carpathians, Boryslav-Pokuttya Unit of the Carpathian Foredeep and their Mesozoic basement in the western Ukraine are presented in the paper. The first recognised oil family consists of almost all oils accumulated in the flysch sequence of the Outer Carpathians and the Carpathian Foredeep which have very similar geochemical characteristics. These oils were generated from Type II or II/III kerogen deposited in clastic sediments. They are low-sulphur and migrated short distances. Slight biodegradation processes are visible only in oils accumulated in shallow deposits in the Skiba Unit. Their source rocks are the Oligocene Menilite Shales from the Boryslav-Pokuttya Unit. Oils from the Kokhanivka and Orkhovychi deposits (the Mesozoic basement of the Carpathian Foredeep) constitute the second family. These oils are extremely heavy, high-sulphur and were generated from high-sulphur Type IIS kerogen deposited in the carbonate environment. The most probable source rocks for these oils are the Upper Jurassic strata. Oil collected from the Vola Blazhivska deposit (the Boryslav-Pokuttya Unit) shows intermediate parameters between the oil families described above. It is characterized by the presence of oleanane and high sulphur content. It was generated from the Menilite Shales containing high-sulphur kerogen. All oils were generated at an early stage or the peak of oil window.

8

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.

9

Carbon isotope stratigraphy of the basal Zechstein (Lopingian) strata in Northern Poland and its global correlation

Peryt T. M., Durakiewicz T., Kotarba M. J., Oszczepalski S., Peryt D.

Geological Quarterly

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2012

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Vol. 56, No 2

285-298

EN

The Kupferschiefer (T1) records a period of basin-wide euxinic conditions, and is thus considered an excellent time-marker in the Zechstein (Lopingian) basin. Previous studies indicated that both the Kupferschiefer and Marl Slate and the overlying Zechstein Limestone (Magnesian Limestone) show remarkable changes in carbon isotopic composition towards higher 131313131313

10

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).

11

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.

12

Origin of natural gases in the autochthonous Miocene strata of the Polish Carpathian Foredeep

Kotarba M. J.

Annales Societatis Geologorum Poloniae

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2011

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Vol. 81, No 3

409-424

EN

Methane concentrations in natural gases accumulated in the autochthonous Miocene strata of the Polish Carpathian Foredeep (between Kraków and Przemyśl) usually exceeded 90 vol%. Methane and part of the ethane were generated during microbial reduction of carbon dioxide in the marine environment, mainly during the sedimentation of Miocene clays and muds. It is possible that this microbial process has continued even recently. Higher light hydrocarbons (mainly propane, butanes and pentanes) were generated during the diagenesis and the initial stage of the low-temperature thermogenic process. Very small changes in the values of geochemical hydrocarbon indices and stable isotope ratios of methane, ethane and propane with depth are evidence for similar gas generation conditions within the whole Badenian and Lower Sarmatian successions. Only in a few natural gas accumulations within the Upper Badenian and Lower Sarmatian reservoirs are thermogenic gases or thermogenic components present, both generated from mixed, type III/II kerogen. These thermogenic gases, now accumulated mainly in the bottom part of Miocene strata, probably resulted from thermogenic processes in the Palaeozoic– Mesozoic basement and then migrated to the Miocene strata along the fault zones. The presence of low hydrogen concentrations (from 0.00 to 0.26 vol%) within the Miocene strata is related to recent microbial processes. Carbon dioxide and nitrogen, which are common minor constituents, were generated in both microbial and low-temperature thermogenic processes. However, CO2 has also undergone secondary processes, mainly dissolution in water during migration. Hydrogen sulphide, which occurs in natural gases of Lower Badenian strata, was most probably generated during microbial sulphate reduction of the Lower Badenian gypsum and anhydrites.

13

Origin of natural gases in the autochthonous Miocene strata of the Ukrainian Carpathian Foredeep and its Mesozoic basement

Kotarba M. J., Koltun Y. V.

Annales Societatis Geologorum Poloniae

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2011

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Vol. 81, No 3

425-441

EN

Methane concentrations in natural gases accumulated in the Lower and Upper Badenian and Lower Sarmatian reservoirs of the Bilche-Volytsia Unit in the western part of the Ukrainian Carpathian Foredeep usually exceed 96 vol%. Methane was generated by microbial reduction of carbon dioxide in the marine environment. Microbial methane and ethane were produced mainly during sedimentation of Miocene clays and muds. It is possible that this microbial process continues today. Higher light hydrocarbons (ethane in part, and mainly propane, butanes and pentanes) were generated during the diagenesis and the initial stage of the low-temperature, thermogenic processes from Type III and III/II kerogen deposited in Miocene strata and/or Middle and Upper Jurassic basement rocks. Limited variations in the values of geochemical hydrocarbon indices and stable isotope ratios of methane, ethane and propane with the depth indicate similar gas generation conditions within the whole Miocene succession. The microbial gases (methane and partly ethane) generated during microbial processes within the Miocene strata later migrated to the Upper Jurassic and the Upper Cretaceous (Cenomanian) reservoirs of the Mesozoic basement, and to the bottommost Lower Badenian reservoirs of the analysed Letnia, Orkhovychi, Rudky and Vereshchytsia fields. The low hydrogen concentrations within the Miocene strata as well as within the Upper Jurassic and the Upper Cretaceous (Cenomanian) reservoirs of the Mesozoic basement, and within the bottommost Lower Badenian reservoirs are also related to microbial processes. Carbon dioxide and nitrogen, which are common minor constituents, were generated by both microbial and low-temperature thermogenic processes. Moreover, CO2 also underwent secondary processes, mainly dissolution in water, during migration. At least part of the nitrogen accumulated in the Rudky field, which is remarkably high in N2 (96.9 vol%), is probably of atmospheric origin and was introduced to the reservoir by secondary recovery methods.

14

Microbial gas system and prospectives of hydrocarbon exploration in Miocene strata of the Polish and Ukrainian Carpathian Foredeep

Kotarba M. J., Peryt T. M., Koltun Y. V.

Annales Societatis Geologorum Poloniae

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2011

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Vol. 81, No 3

523-548

EN

Molecular composition of natural gases accumulated in autochthonous Miocene strata of the Polish and Ukrainian Carpathian Foredeep is dominated by methane, which usually constitutes over 98 vol%. Methane was generated by the carbon dioxide reduction pathway of microbial processes. Ethane was generated both during microbial and thermogenic processes ("oil window") and propane at the initial stage of the low-temperature thermogenic processes, and also by the microbial processes. The rhythmic and cyclic deposition of Miocene clays and sands as well as the vigorous generation of microbial methane caused that the gas produced in claystone beds was accumulated in the overlaying sandstones, and capped, in turn, by the succeeding claystones. Such generation and accumulation system of microbial gases gave rise to the formation of multi-horizontal gas fields. Analysis of the distribution of immature humic dispersed organic matter in the Upper Badenian and Lower Sarmatian sequences indicates that it is practically homogeneous. A migration range of microbial gases was insignificant and locations of their accumulations would depend only on the existence of proper type of traps (compactional anticlines situated above basement uplifts, sealed by the Carpathian Overthrust and/or by faults; stratigraphic pinching out and stratigraphic traps related to unconformities). Another situation is encountered in the south, beneath the Carpathian Overthrust. The thickness of the autochthonous Miocene strata in this area is more than 1,500 metres. Geochemical studies reveal that from a depth of 2,500 metres starts the process of low-temperature thermogenic hydrocarbon generation (“oil window”). At greater depths, more than 7,500 metres, within the autochthonous Lower Miocene basin only the high-temperature methane ("gas window") could be produced and accumulated.

15

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.

16

Geology and petroleum geochemistry of Miocene strata in the Polish and Ukrainian Carpathian Foredeep and its Palaeozoic–Mesozoic basement

Kotarba M. J., Peryt T. M.

Annales Societatis Geologorum Poloniae

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2011

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Vol. 81, No 3

211-220

EN

This thematic issue of Annales Societatis Geologorum Poloniae contains a set of papers presenting results of a special research project entitled "Petroleum exploration prospectives and hydrocarbon potential of the Miocene strata and Mesozoic–Palaeozoic basement in the borderland area of Poland and Ukraine", led by research teams from the AGH University of Science and Technology in Kraków and the Polish Geological Institute – National Research Institute in Warsaw. The objective of this paper is determination of the geological and geochemical conditions, 1-D and 2-D modelling of petroleum processes and petroleum systems and their influence on the prospectives of hydrocarbon exploration of the Miocene strata in the Polish and Ukrainian Carpathian Foredeep and its Palaeozoic–Mesozoic basement. In particular, a coherent model of geological structure of the area, based both on the synthesis of the earlier published data and on new results of palynological studies of the Upper Precambrian and Lower Palaeozoic, is given. New data on microfacies of the Upper Jurassic and Lower Cretaceous strata and on sedimentology, geochemistry and micropalaeontology of the Middle Miocene rocks are presented.

17

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.

18

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".

19

Ocena intensywności wtórnych procesów w złożach ropy naftowej mezozoicznego podłoża zapadliska przedkarpackiego na podstawie analizy lekkich węglowodorów ciekłych

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

Prace Naukowe Instytutu Nafty i Gazu

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2010

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nr 170 wyd. konferencyjne

663--667

PL

Na podstawie analizy chromatograficznej surowej ropy naftowej ustalono skład i dystrybucję węglowodorów w zakresie CS-C30 ze szczególnym uwzględnieniem analizy związków zawierających od 5 do 9 atomów węgla w cząsteczce. Analizą objęto ropę naftową z akumulacji w utworach jury i kredy mezozoicznego podłoża zapadliska przedkarpackiego: Pławowice, Grobla, Tarnów (jura), Jastrząbka Stara, Góra Ropczycka i Brzezówka oraz przypływu w odwiercie Opaka-1. Największą intensywność procesów frakcyjnego odparowania węglowodorów stwierdzono w ropie pochodzącej z akumulacji Góry Ropczyckiej. W ropie pobranej ze złoża Brzezówka procesy te miały ograniczony zasięg. Ropa ze złóż Pławowice i Jastrząbka Stara jest częściowo zbiodegradowana. Skład węglowodorów ropy naftowej ze złóż Grobla i Tarnów (jura) oraz z przypływu w odwiercie Opaka-1 nie wykazuje oddziaływania procesów wtórnych.

EN

The composition and distribution of hydrocarbons (HC) were determined in the range of C5-C30 based on the results of chromatographic analysis of crude oil. Special attention was paid to components containing from 5 to 9 carbon atoms in a molecule. Analysis was made for oils accumulated in the Upper Jurassic and Cretaceous strata of the Mesozic basement of the Carpathian Foredeep in Pławowice, Grobla, Tamów (Jurassic), Jastrząbka Stara, Góra Ropczycka and Brzezówka accumulations, and oil inflow in the Opaka-1 well. The highest intensity of the fractional evaporating process was affirmed in oil taken from the Góra Ropczycka deposit. In oil collected from Brzezówka deposit these processes had a limited range. Oils from Pławowice and Jastrząbka Stara deposits were partly biodegraded. Hydrocarbon composition of oils taken from Grobla and Tarnów (Jurassic) deposits and from inflow in Opaka-1 well did not show presence of any secondary processes.

20

Origin of oils accumulated in the Middle Cambrian reservoirs of the Polish part of the Baltic region

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

Geological Quarterly

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2010

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Vol. 54, No 2

205-216

EN

We have examined 21 samples of crude oils accumulated in the Middle Cambrian sandstone reservoirs from the Polish part of the Baltic region. All the crude oils have similar parameters and indices, which suggests generation from the same source rock. Evaporative fractionation and biodegradation processes were detected in oil collected from the B4-N1/01 borehole. All crude oils have high gravities and low-sulphur contents, less than 0.3 wt.%, which suggests that their source rock contained low-sulphur kerogen deposited in a clastic environment. A low asphaltenes content (below 0.3 wt.%) and high saturate/aromatic hydrocarbon ratios indicate long migration distances or high thermal maturities. The longest migration distance was probably attained by oils from the arnowiec and B16 deposits. The biomarker data indicate an algal origin for the source organic matter deposited under conditions of clastic sedimentation. The stable carbon isotope data support this observation. The maturity of the oils analysed varies from ca. 0.75 to ca. 1.05% on the vitrinite reflectance scale. Unlike the B6, B16, Dbki and arnowiec accumulations, oils from the B3 and B4 accumulations reveal the lowest maturity.