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Polish shale formation evaluation based on chemical and isotope composition of natural gas

Janiga Marek

Prace Naukowe Instytutu Nafty i Gazu

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2024

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nr 241

1--115

EN

The relationship between the change of carbon isotope composition of gaseous hydrocarbons in natural gas and the increase of source rock organic matter thermal maturity are especially important in the petroleum geochemistry. The thermal maturity evaluation and interpretation based on the chemical and isotope compositions is commonly performed for natural gases conventional reservoirs, shales, coals, seeps and other geological habitats. The carbon isotope composition of individual hydrocarbons in gas samples provided by the compound specific isotope analysis (CSIA) can be used for interpretation and correlation purposes. On the basis of the δ¹³C value of methane, ethane and propane, the estimation of thermal transformation degree of the source rock (from which the gas was generated) can be made. In this work, organic geochemistry methods (chemical and isotope composition of gas and pyrolysis indices) are used for the shale petroleum system evaluation and to find the values of parameters determining the sweet spot. The case study of five exploration wells located in the north of Poland is presented and discussed. The work presents results of chemical/isotope composition analyses of natural gases and geochemical Rock-Eval analyses from five wells exploring the Silurian and the Ordovician shale formations. The statistical analyses were conducted with the use of the following: descriptive, correlation and liner regression. Using all the results as one statistical population, Pearson’s linear correlation coefficients of the gas isotope composition with the pyrolytic and molecular indices were calculated. Surprisingly, there are no high correlations between the pyrolytic indices and the isotope composition or the chemical indices. Moderate correlations are between maturity of the source organic matter (Tmax) and the isotope composition of carbon in methane (r = 0.63). The results of carbon isotope analyses clearly differentiate samples from each well, only L-1 and O-2 wells natural gases are quite similar. Methane, ethane and propane δ¹³C values are progressively higher in sequence L-1, O-2, K-1, B-1 and W-1. The thermal maturity of the source organic matter was assessed using Tang’s mathematical model including the share of biogenic methane. The thermal maturity corresponds mainly to the range from 0.9% (L-1 and O-2) to 1.5% (B-1 and W-1) vitrinite reflectance. Natural gas compositions shows mixing with the biogenic gas (below approximately 25%). A noticeable drift of methane towards negative values in all wells samples confirmed mixing with biogenic gas (with the use of the natural gas plot - Chung plot). Values of the isotope composition of ethane and propane were also skewed (especially in W-1 and B-1; a little less in O-2 and K-1 wells). This confirmed the occurrence of secondary cracking. The inversion of the isotope composition of carbon in methane, ethane and propane (the roll-over effect) does not occur in analysed gases. Usage of the diagram (δ¹³C-C₃ - δ¹³C-C₂) vs (δ¹³C-C₂ - δ¹³C-C₁) is considered to be the best way of presenting of the isotope data. For all samples, the difference between ethane and methane (δ¹³C-C₂ - δ¹³C-C₁) is constantly decreasing with an increase of thermal maturity. The propane and ethane difference (δ¹³C-C₃ - δ¹³C-C₂) is increasing at lower thermal maturities (to approximately 1,5% VRo), and decreasing with higher values of maturity. This suggests presence of the secondary cracking, resulting in the sweet spot occurrence. Using the hydrocarbon composition, molecular indices were calculated (C₁/C₂+₃, C₂/C₃, i-C₄/n-C₄ and i-C₅/n-C₅). These indices are a valuable source of information about natural gas, whose complete composition analyses can be affected by the manner of taking a sample and the type of well. Similarly to the isotope composition the samples plot progressively in sequence L-1 and O-2, K-1, B-1 and W-1. The main aim of this work was to establish the values of chemical and isotope composition parameters determining sweet spots. Using the composition of gases from W-1 well (the highest thermal maturity of the source organic matter) and the Barnett reference data, approximate values at which prospective levels can be expected were defined.

PL

Skład chemiczny i izotopowy gazu zmienia się wraz termiczną dojrzałością źródłowej substancji organicznej. Suchy gaz biogeniczny o bardziej ujemnych wartościach δ¹³C przechodzi w gaz mokry okna ropnego, a następnie w suchy gaz okna gazowego o wartościach δ¹³C zbliżających się do zera. Dla gazów z formacji łupkowych zależności te są identyczne, a analizy składu chemicznego i izotopowego gazu z formacji łupkowych są wykorzystywane do typowania obszarów perspektywicznych tzw.: „sweet spots”. Celem pracy było znalezienie parametrów i ich wartości, na podstawie składu chemicznego i izotopowego, oznaczających prawdopodobne wystąpienie „sweet spot”. W tym celu wykorzystano wyniki analiz gazu z pięciu odwiertów poszukiwawczych z północy Polski. W pracy przedstawiono wyniki analiz składu chemicznego i izotopowego gazów ziemnych oraz wyniki analiz geochemicznych Rock-Eval z pięciu odwiertów eksplorujących formacje łupkowe syluru i ordowiku. Analizy statystyczne przeprowadzono z wykorzystaniem statystyki opisowej, korelacji i regresji liniowej. Wykorzystując wszystkie wyniki jako jedną populację statystyczną, obliczono współczynniki korelacji liniowej Pearsona dla składu izotopowego poszczególnych węglowodorów gazu ziemnego z parametrami pirolitycznymi i wskaźnikami wyliczonymi na podstawie składu chemicznego. Korelacje pomiędzy parametrami pirolitycznymi a składem izotopowym lub wskaźnikami chemicznymi nie są wysokie. Przykładowo umiarkowane korelacje występują pomiędzy dojrzałością termiczną źródłowej materii organicznej (Tmax) a składem izotopowym węgla w metanie (r = 0,63). Wyniki analiz składu izotopowego węgla wyraźnie różnicują próbki z każdego odwiertu (poza gazami z odwiertów L-1 i O-2). Wartości δ¹³C metanu, etanu i propanu są progresywnie wyższe w sekwencji L-1, O-2, K-1, B-1 i W-1. Dojrzałość termiczną źródłowej materii organicznej oceniono wykorzystując model matematyczny Tanga uwzględniający również udziału metanu biogenicznego. Dojrzałość termiczna odpowiada głównie zakresowi od 0,9% (L-1 i O-2) do 1,5% (B-1 i W-1) w skali refleksyjności witrynitu. Skład wszystkich gazów ziemnych wskazuje na mieszanie z gazem biogenicznym (udział biometanu w gazie poniżej około 25%). Odchylenie wartości δ¹³C metanu w kierunku bardziej ujemnych we wszystkich próbkach również potwierdziło mieszanie z gazem biogenicznym (graficzny model Chunga tzw.: „natural gas plot”). Także wartości składu izotopowego węgla etanu i propanu odbiegały od teoretycznych (zwłaszcza w odwiertach W-1 i B-1; nieco mniej w odwiertach O-2 i K-1). Potwierdza to występowanie wtórnego krakingu. W najbardziej produktywnych złożach gazu łupkowego występuje zwykle inwersja składu izotopowego węgla metanu, etanu i propanu (tzw.: „roll-over effect”). W analizowanych gazach zjawisko to nie wystąpiło, ale dostrzegalne są zmiany w różnicach (δ¹³C-C₃ - δ¹³C-C₂) i (δ¹³C-C₂ - δ¹³C-C₁). Wykorzystanie wykresu zestawiającego obydwie te różnice uznano za najlepszy sposób przedstawienia wyników przy omawianiu zjawiska wtórnego krakingu, który może prowadzić do inwersji składu izotopowego. Dla wszystkich próbek różnica między etanem i metanem (δ¹³C-C₂ - δ¹³C-C₁) stale maleje wraz ze wzrostem dojrzałości termicznej. Różnica propanu i etanu (δ¹³C-C₃ - δ¹³C-C₂) wzrasta przy niższych dojrzałościach termicznych (do około 1,5% VRo) i maleje przy wyższych wartościach termicznej dojrzałości. Wykorzystując wyniki analiz składu chemicznego gazów obliczono wskaźniki C₁/C₂+₃, C₂/C₃, i-C₄/n-C₄ oraz i-C₅/n-C). Wskaźniki te są cennym źródłem informacji o gazie ziemnym, pozwalając uniknąć wpływu sposobu poboru i rodzaj odwiertu na skład chemiczny gazu. Podobnie jak przy wynikach analiz składu izotopowego, próbki różnicują się i tworzą sekwencję L-1 i O-2, K-1, B-1 i W-1. Głównym celem pracy było wybranie parametrów/wskaźników i ich wartości determinujących strefy perspektywiczne w formacjach łupkowych. Wykorzystując skład gazów z odwiertu W-1 (najwyższa dojrzałość termiczna źródłowej materii organicznej) oraz dane referencyjne z formacji Barnett określono przybliżone wartości składu izotopowego metanu, etanu i propanu oraz wskaźników C₁/C₂+₃, i-C₄/n-C₄ i i-C₅/n-C₅ przy których można spodziewać się wystąpienia „sweet spots”.

2

Mapping a fracture network formed by hydraulic fracturing in a shale gas reservoir

Węglińska Elżbieta, Leśniak Andrzej, Pasternacki Andrzej, Wandycz Paweł

Geology, Geophysics and Environment

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2024

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Vol. 50, no. 3

213--230

EN

Microseismic monitoring is an important technique that can be used to identify fractures in rock mass. The aim of this article is to identify, on the basis of the location of microseismic events, structures formed by hydraulic fracturing in the Wysin-2H/2Hbis horizontal well from the Baltic Basin in northern Poland, and to compare the patterns of these structures with the direction of regional stresses. The authors proposed a novel multi-step workflow for finding these structures. To be able to delineate the structures from microseismic events with greater accuracy, a collapsing algorithm was used. Then, based on the Hierarchical Density-Based Spatial Clustering of Applications with Noise (HDBSCAN) clustering algorithm and the elongation coefficient of each cluster, probable fissures were identified and compared against the maximum horizontal stress direction. In addition, based on the 3D seismic data from the Wysin and the calculated geomechanical parameters in the monitoring well, the probability classes of brittleness indices in the LMR (λρ-μρ) parameter domain were determined. A comparative analysis was performed between the two variants of microseismic event location (before and after the collapsing procedure) and the estimated probability of a given class of brittleness index. The comparison of the event location with the 3D seismic data was used to validate the results before and after collapsing due to the high resolution of the seismic method. It is shown that the collapsed events appeared in more rigid regions, where more energy release is expected.

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Challenges to the Development of Unconventional Natural Gas – The Case of Shale Gas

Le Minh Thong, Tran Van Hiep, Do Huu Tung

Inżynieria Mineralna

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2023

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no. 2, vol. 1

113--120

EN

The world is undergoing a radical transition to a low-carbon economy and natural gas is considered an important bridge in the transition of energy in the world. The potential for natural gas, especially unconventional gas, is very large, which will significantly affect the future energy structure in all regions of the world. However, the conditions for developing these resources are different between regions and countries. The development of unconventional gas is now facing many challenges, even opposition because the problem of extracting unconventional gas is very complex and the total impact is unknown. Therefore, at present, the expansion of unconventional gas remains a question for countries that possess and desire to exploit these resources. This article will analyze the opportunity and challenges of unconventional gas relying on the development of shale gas in recently.

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Life Cycle Assessment of unconventional hydrocarbons deposits of shale and tight gas production in Poland

Wójcik Monika, Gładysz Paweł, Kostowski Wojciech, Łodziński Krzysztof

Gaz, Woda i Technika Sanitarna

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2022

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Nr 10

16--22

EN

Shale and tight gas production create a potential threat to the environment. In Poland, no comprehensive guidelines for Life Cycle Assessment (LCA) have been prepared so far. The paper presents a proposal for Life Cycle Assessment (LCA) which can be used to assess the impact of production of unconventional hydrocarbons processes in Polish circumstances. It can be also a complement to environmental risk assessment. We used the methodology of Life Cycle Assessment (LCA) and estimated the environmental impact of shale and tight gas exploration and operation for several elements like: global warming, water consumption, human carcinogenic toxicity, terrestrial acidification, and others.

PL

Procesy poszukiwania i wydobycia gazu ze złóż niekonwencjonalnych typu shale (gaz z łupków) oraz tight (gaz zamknięty) stwarzają potencjalne zagrożenie dla środowiska. W Polsce nie zostały dotychczas opracowane kompleksowe wytyczne dotyczące oceny ryzyka środowiskowego oraz oceny cyklu życia (LCA) dla produktów takich jak shale i tight gas. W niniejszym artykule zaprezentowano analizę procesów poszukiwania i eksploatacji shale i tight gas przy użyciu metodyki oceny cyklu życia (LCA) dla warunków polskich. Może ona stanowić uzupełnienie analizy ryzyka środowiskowego. Metodyka oceny cyklu życia (LCA) została wykorzystana do szacowania wpływu procesów poszukiwania i eksploatacji shale i tight gas na elementy takie jak: globalne ocieplenie, zużycie wody, oddziaływanie rakotwórcze na człowieka, zakwaszenie gleb i inne.

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Termodynamika układów węglowodorowych w nanoporowych strukturach złożowych

Nagy Stanisław, Siemek Jakub

Wiadomości Naftowe i Gazownicze

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2020

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R. 23, Nr 7 (261)

4--11

PL

Gaz ziemny z łupków ze złóż niskoprzepuszczalnych piaskowcowych (typu ‘tight’) i łupkowych (typu ‘shale’) jest jednym z najważniejszych paliw kopalnych uznanych jako paliwo ‘przejściowe’ w okresie transformacji energetycznej. Niniejszy artykuł opisuje złożone zjawiska związane z wpływem rozmiarów kanałów porowych, adsorpcji i kapilarnej kondensacji w strukturach nanoporowych. Zjawiska towarzyszące układom nanoporowym powodują też zmianę położenia punktu krytycznego, co wpływa zasadniczo na przesunięcie równowagi fazowej. Omówiono zmodyfikowany dwufazowy model równowagowy dwufazowy w obszarze mikro i nanoporów. Pokazano przykłady zmiany krzywych nasycenia dla wybranego składu układu gazowo-kondensatowego.

EN

Unconventional natural gas from low-permeable sandstone (tight) and shale reservoirs is one of the most important fossil fuels recognized as ‘transient’ fuels during the energy transformation. This paper describes complex phenomena related to confining conditions adsorption and capillary condensation in nanopore structures. The phenomena associated with nanopore systems also cause a critical point to shift, which essentially move the phase equilibria. Paper discusses a modified two-phase equilibrium model in micro and nanopore systems. Examples of changes in phase envelope curves are presented in the selected composition of gas-condensate systems.

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Ewaluacja sweet spotów w polskich formacjach łupkowych w odniesieniu do wybranych parametrów geochemicznych

Matyasik Irena, Janiga Marek, Spunda Karol

Nafta-Gaz

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2020

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R. 76, nr 2

76--90

PL

W artykule skupiono się na parametrach geochemicznych kluczowych dla oceny potencjału węglowodorowego formacji łupkowych (zawartość substancji organicznej oraz jej termiczna dojrzałość i stopień transformacji). Przeprowadzono analizę porównawczą pomiarów gazu pozyskanego w procesie desorpcji rdzeni z analizą nasyceń uzyskanych z pirolizy Rock-Eval i określono procent zachowania wolnych węglowodorów przy obliczonej generacji w poziomach macierzystych. Zaobserwowano duże rozbieżności pomiędzy pomierzonymi wartościami refleksyjności macerałów witrynitopodobnych lub na zooklastach a obliczonymi wartościami VR z parametru Tmax. Oznacza to ograniczoną stosowalność i uniwersalność wzoru według Jarvie (Wüst, 2013). Opracowano, na podstawie dużej populacji próbek, nowy wzór przeliczeniowy. Dodatkowo w artykule przedstawiono wyniki analiz składu izotopowego. Stwierdzono duże zróżnicowanie wartości δ13C metanu, etanu i propanu pomiędzy odwiertami. Udział wyższych węglowodorów w składzie gazów jest bardzo wysoki, co może oznaczać termogeniczne pochodzenie gazu. Większość próbek to gaz związany z ropą naftową i gaz mieszany, jedna próbka to gaz związany z kondensatem (wykres według Petersa). Generacja gazu z obydwu odwiertów odpowiada zakresowi okna ropnego do początku okna gazowego (VR od około 0,6% do około 1,35%) (Peters et al., 2005). Dodatkowo, wykorzystując dane z eksperymentów degazacyjnych (ilości gazu całkowitego) oraz parametry pirolityczne otrzymywane z analiz Rock-Eval (Tmax i TOC), stwierdzono, że korelacja pomiędzy dojrzałością źródłowej substancji organicznej (określaną na podstawie Tmax) a ilościami gazu jest niewielka (r = 0,37 dla gazu całkowitego). Natomiast korelacja pomiędzy zawartością węgla organicznego (TOC) a ilościami gazu jest wysoka dla gazu całkowitego (r = 0,70).

EN

The article focuses on the geochemical parameters of key importance to the assessment of the hydrocarbon potential of shale formations (the content of organic matter and its thermal maturity and degree of transformation). A comparative analysis of the measurements of gas obtained in the process of core desorption with the analysis of saturations obtained from Rock-Eval pyrolysis was performed. Percentage of retained free hydrocarbons in source levels at the calculated generation was determined. Large discrepancies were observed between the measured reflectance values of vitrinite-like macerals or on zooclasts and the calculated VR values from the Tmax parameter. This means limited applicability and universality of Jarvie formula (Wüst, 2013). A new conversion formula was calculated based on a large sample population. Additionally, the article presents the results of isotopic composition analyzes. Large differences in the δ13C methane, ethane and propane values were stated between the wells. The content of higher hydrocarbons in the gas composition is very high, which may indicate thermogenic origin. Most samples are oil-related gas and mixed gas, one sample is condensate related gas (Peters chart). The gas generation from both wells corresponds to the range of the oil window to the beginning of the gas window (VR from about 0.6 to about 1.35%) (Peters et al., 2005). In addition, using data from degasification experiments (total gas quantities) and pyrolysis parameters obtained from Rock Eval analyzes (Tmax and TOC), it was found that the correlation between the maturity of the source organic matter (determined on the basis of Tmax) and the amounts of gas is small (r = 0.37 for total gas). In contrast, the correlation between the organic carbon content (TOC) and the amounts of gas is high for total gas (r = 0.70).

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Lower Paleozoic oil and gas shale in the Baltic-Podlasie-Lublin Basin (central and eastern Europe) - a review

Poprawa Paweł

Geological Quarterly

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2020

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Vol. 64, No. 3

515--566

EN

In the Baltic-Podlasie-Lublin Basin, four potential lower Paleozoic shale reservoirs are identified: the Piaśnica, Sasino and Jantar formations, as well as the Mingajny shale. These units were diachronously deposited during the starved stages of Caledonian foredeep basin development, in the course of rising or high eustatic sea level. Across most of the basin, the shale formations analysed are saturated with light oil and condensate, and they are buried to depths of 2300-3500 m. The shale reservoirs reach the wet gas window at burial depths of 2800-4000 m, while dry gas accumulations occur at depths exceeding 3500-5000 m, except in the Biłgoraj-Narol Zone. The shale analysed might be generally classified as a moderate to low quality, and locally high quality, unconventional reservoir. Within the shale net pay zones, the average TOC content is 2-5 wt.% TOC. The exceptions are the Piaśnica Formation, for which this is 5-12 wt.%, and the Mingajny shale, which is TOC-lean (1.4-1.7 wt.%). The thickness of the shale net pay intervals in the most favourable locations, mainly on the Łeba Elevation, generally reaches 20 m, and locally exceeds 35 m. The shale reservoirs are saturated with hydrocarbons of good quality. Their permeability is low to moderate, often in the range of 150-200 mD, while total porosity average per borehole is commonly exceeds 6 %, reaching up to 10% at maximum, which might be considered as moderate to good. The clay minerals content is moderate to high (30-50%), and geomechanical characteristics of the shale formations are intermediate between brittle and ductile. No overpressure occurs in the basin, except for a dry gas zone in the SW Baltic Basin. In the Biłgoraj-Narol Zone, and to a lesser degree also in the Lublin region, pronounced tectonic deformation significantly limits shale gas/oil potential. Among 66 exploration boreholes drilled in the basin so far, only 5 were lateral boreholes with representative production test results. Hydrocarbon flow from the best boreholes was low to moderate, equal to 11.2 to 15.6 thousand m3/day for gas, and 157 bbl/day (~21.4 ton/day) for oil. There is, however, high potential to improve production flow rates, connected with the fracturing of two net pay intervals at one time, as well as with significant technological progress in the exploitation of shale basins during the last 5 years. Commercially viable production might be achieved for a single borehole with estimated ultimate recovery exceeding 30-50 thousand tons of oil, or 60-90 million m3 of gas.

8

Toxicological evaluation of thermal treatment of drilling waste from shale gas exploration in Poland

Drzewicz Przemysław, Nałęcz-Jawecki Grzegorz, Drobniewska Agata, Zgadzaj Anna, Smoliński Adam, Krzan Marcel, Starzycka Anita

Ecological Chemistry and Engineering. S

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2019

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Vol. 26, nr 1

45--57

EN

The oil containing drilling waste is a worldwide environmental problem associated with oil and gas exploration. In Poland, the problem of the drilling waste has become important since starting of shale gas exploration. The results of thermal treatment of drilling waste from shale gas exploration are presented. It has been shown that organic content vaporized completely at temperature up to 500 °C. The main problem is high content of chloride, sulfate, sodium, potassium, magnesium in the waste and its water leachate. Toxicity tests confirmed that high salinity of the samples pose important risk for environment. Due to the high content of barium, the drilling waste may be utilized in production of cement with high chemical and heat resistance and opaque to X-ray. Thermal treatment process is a viable option for remediation of the drilling waste; however, the product of the process needs further treatment in order to remove its high salinity.

9

Multipurpose usage of magnetic proppants during shale gas exploitation

Bogacki Jan, Zawadzki Jarosław

Ecological Chemistry and Engineering. S

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2019

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Vol. 26, nr 1

37--44

EN

Magnetic material may be added to proppant, as the magnetic marker allows to determine the range and efficiency of hydraulic fracturing. However, magnetic proppant may be also used in flowback fluid treatment and monitoring of environmental pollution. As a result of shale gas hydraulic fracturing, large volume of flowback fluid is created. Flow back fluid have similar properties to fracturing fluid, but it is potentially enriched with large amount of salts and organic compounds leached from shale. Magnetic proppant may serve as a heterogeneous catalyst during organic pollutants decomposition. Additionally, in case of leakage and consequently the fracturing fluid pollution, magnetic proppant is placed into the soil environment. It can be detected using magnetometric methods. This article discusses the above-mentioned issues based on the knowledge and experience of the authors and the literature review.

10

Unconventional hydrocarbon prospects in Ordovician and Silurian mudrocks of the East European Craton (Poland) : Insight from three-dimensional modelling of total organic carbon and thermal maturity

Papiernik Bartosz, Botor Dariusz, Golonka Jan, Porębski Szczepan J.

Annales Societatis Geologorum Poloniae

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2019

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Vol. 89, No. 4

511-- 533

EN

Three-dimensional, structural and parametric numerical modelling was applied to unravel the unconventional hydrocarbon potential of a W-dipping, Lower Palaeozoic mudrock succession, which subcrops for some 700 km in the Baltic, Podlasie and Lublin basins across the SW margin of East European Craton in Poland. Input data comprised structural and thickness maps of Ordovician and Silurian strata and the results of thermal maturity (mean vitrinite-equivalent reflectance, % Ro) and total organic carbon (TOC, % wt.) modelling. A new, spatial interpretation of vitrinite-reflectance variability indicates that the regional, W-increasing thermal maturity pattern breaks into a series of domains, bounded by abrupt maturity variations. In total, 14 tectono-thermal domains were recognised and their boundaries traced to known and inferred faults, mostly of NW‒SE and NE‒SW orientations. On the basis of a combination of thermal maturity and total organic carbon levels (0.6% > Ro<2.4%, and TOC >1.5% wt.), good-quality, unconventional reservoirs can be expected in the Sasino Formation (Caradoc) and Jantar Formation (early Llandovery) in the central and western Baltic Basin. The Jantar Formation also is likely to be prospective in the western Podlasie Basin. Marginal-quality reservoirs may occur in the Sasino and Jantar formations within the Podlasie and Lublin basins and in the Pasłęk Formation (late Llandovery) across all basins. Poor- to moderate-quality, unconventional reservoirs could be present in the Pelplin Formation (Wenlock) in the Lublin and southern Podlasie basins. In spite of a considerable hydrocarbon loss during multiphase basin inversion, the Ordovician and Silurian mudrocks still contain huge quantities of dispersed gas. Successful exploitation of it would require the adoption of advanced fracking methods.Lower Palaeozoic, shale gas, shale oil, Baltic Basin, Lublin-Podlasie Basin, total organic carbon, thermal maturity, structural-parametric model.

11

Thermal history of Lower Palaeozoic rocks from the East European Platform margin of Poland based on K-Ar age dating and illite-smectite palaeothermometry - 481 – 509

Kowalska Sylwia, Wójtowicz Artur, Hałas Stanisław, Wemmer Klaus, Mikołajewski Zbigniew, Buniak Arkadiusz

Annales Societatis Geologorum Poloniae

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2019

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Vol. 89, No. 4

481--509

EN

Large-scale shale gas prospecting in the Polish part of the East European Platform did not discover large reserves of this resources. The article presents new research indicating that one of the reasons for the lack of shale gas relates to the thermal history of the Lower Palaeozoic rocks. Illite-smectite palaeothermometry was used to reconstruct the history of the platform and determine the maximum temperatures to which these rocks were subjected. The age of illitisation was also constrained using the K-Ar method. This method allowed precise dating of the maximum age of thermal transformations due to the deposition of numerous pyroclastic horizons (K-bentonite) throughout the entire geological profile from the Cambrian to the Silurian. Isotopic dating was made on over 53 samples of Lower Palaeozoic bentonites and low-grade metamorphic clays. These results were supplemented by analysis of the degree of thermal (smectite to illite) transformation in the profiles of 37 deep boreholes. 11 zones could be distinguished with different tectonic histories within the Polish part of the East European Platform edge. Maximum heating occurred in this region at about 320–340 Ma, corresponding to the Early Carboniferous or the turn of the Early and Late Carboniferous, phase A of the Variscan orogeny, known as the Sudetian phase. In the southern part of study area, the maximum of thermodiagenesis is slightly younger – 270–290 Ma, which responds to the Early Permian, the Asturian phase, the last phase of the Variscan orogeny. This means that the generation of hydrocarbons occurred before significant Mesozoic exhumation of the Polish part of the East European Platform, which led to the escape of a considerable amount of the gas generated. The study also presents the results of an interlaboratory comparison of illite age dating using the K-Ar and Ar-Ar methods. The comparison was conducted to find out what realistic error should be considered when interpreting geological K-Ar dating results.

12

Reconstruction of initial thickness and geometry of the Lower Palaeozoic strata in the Podlasie and Baltic basins, East European Craton

Barmuta Jan, Barmuta Maria, Golonka Jan, Papiernik Bartosz

Annales Societatis Geologorum Poloniae

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2019

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Vol. 89, No. 4

471--480

EN

The aim of this study was to use the structural restoration technique to verify the correctness of the structural and palaeothickness maps created during the BLUE GAS Project. On the basis of well data as well as refined structural and palaeothickness maps of Cambrian, Ordovician, Silurian, Devonian, Carboniferous, Permian, Triassic, Jurassic and Cretaceous horizons, a cross-section running across the Baltic Basin, the Mazury High and the Podlasie Basin was created. During the restoration process, the effects of compaction and fault activity were removed sequentially. The amount of erosion was estimated on the basis of the corrected palaeothickness maps. The resulting restoration is geologically reasonable and therefore both the structural and palaeothickness maps should be regarded as reliable. The reconstruction also allowed reproduction of the initial geometry and thickness of the Cambrian–Devonian strata and the recognition of three main episodes in the evolution of the sedimentary cover of this part of the East European Craton. The first episode was related to the deposition of the Lower Palaeozoic (up to the Lower Devonian) sedimentary complex on the relatively flat surface of the East European Craton edge. During the second episode, lasting most probably to the Permian, the Baltic and Podlasie Basins subsided significantly. The amount of subsidence was much higher in the Podlasie Basin. The third episode is related to the deposition of the almost flat-lying Mesozoic–Cainozoic complex.

13

Petroleum generation and expulsion in the Lower Palaeozoic petroleum source rocks at the SW margin of the East European Craton (Poland)

Bator Dariusz, Golonka Jan, Zając Justyna, Papiernik Bartosz, Guzy Piotr

Annales Societatis Geologorum Poloniae

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2019

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Vol. 89, No. 2

153--174

EN

In this work, 1-D numerical modelling of petroleum generation and expulsion processes in the Upper Ordovician and Lower Silurian source rocks was carried out in over sixty wells along the SW margin of the East European Craton (EEC) in Poland. Lower Palaeozoic sediments were subjected to rapid burial in the Palaeozoic and then were uplifted in several phases, but with the predominance of the late Variscan tectonic inversion. The thermal maturity of organic matter in the Lower Palaeozoic strata indicates the advancement of the generation processes from the phase of low-temperature thermogenic processes in the NE part of the Baltic and Podlasie-Lublin basins to the overmature stage along the zone adjacent to the Teisseyre-Tornquist Zone (TTZ). The results of modelling of generation and expulsion show that these processes took place mainly in the Devonian and Carboniferous periods and in the westernmost part (along the TTZ), even in the latest Silurian. The hydrocarbon expulsion took place with a small - delay after generation. During the Mesozoic and Cainozoic, generation processes practically were not resumed or intensified. Nevertheless, it was found that zones with an increased shale gas potential can occur only in a relatively narrow belt on the SW slope of the EEC, parallel to the edge of the TTZ. The most promising seem to be Caradocian, Llandovery and the Wenlock between the Lębork IG-1 and Kościerzyna IG-1 wells in the Baltic Basin, and the Wenlock source rocks in the Podlasie-Lublin Basin between the Okuniew IG-1, Łopiennik IG-1 and Narol IG-1 wells. Most of the hydrocarbons were subjected to expulsion and possible migration. As a result, there was a large dispersion of the hydrocarbons generated. The chance of preservation of these hydrocarbons in the source rocks is small.

14

Methodology and results of digital mapping and 3D modelling of the Lower Palaeozoic strata on the East European Craton, Poland

Papiernik Bartosz, Michna Michał

Annales Societatis Geologorum Poloniae

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2019

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Vol. 89, No. 4

405--427

EN

The paper presents a multi-phase and multi-stage methodology of 3D structural-parametric modelling and mapping that has been applied during implementation of the GAZGEOLMOD project. The core of the applied processing workflows is a 3D geological model constructed in Petrel, which functions as a spatial database for all kinds of geological models. The first phase of the workflow comprised an extended process of database project building that was very intensive at the beginning of the project and continued to its end. The second phase of processing consisted of a complex process of mapping and structural modelling that is performed in 8 stages, allowing for iterative improvements of model resolution. During the realization of stages 1 to 7, processing was run independently for the Baltic (BB), Podlasie (PB) and Lublin Basins (LB). The workflow included the following stages: (1) unification and digitization of published and on file analogue and digital, structural maps; (2) preliminary reinterpretation, including adjustment to stratigraphy data acquired from archives; (3) adjusting the maps to the primary results of seismic interpretation, mainly from archival data; (4) digitization and gridding of pre-existing palaeothickness maps and updates of them with data from boreholes completed after 2009; the reinterpretation of the palaeothickness maps into contemporary thickness maps; (5) elaboration of the primary structural 3D models for the three basins; (6) increasing of the stratigraphic resolution of models up to the rank of the geological epoch for Ordovician–Silurian strata; (7) conversion of basin-scale structural models into a 2D grid, and their merging into platform-scale surfaces, resulting in 45 structural and thickness maps; finally, they were adjusted to the results of seismic interpretation and sedimentological studies, obtained in the project; and (8) completion of the resulting structural models for each of the basins and for the entire Polish part of the East European Craton in several different versions. In the third phase of processing, parametric models of vitrinite reflectance (Ro) and Total Organic Carbon (TOC) were estimated.

15

Burial and thermal history of the Lower Palaeozoic petroleum source rocks at the SW margin of the East European Craton (Poland)

Botor Dariusz, Golonka Jan, Anczkiewicz Anneta A., Dunkl István, Papiernik Bartosz, Zając Justyna, Guzy Piotr

Annales Societatis Geologorum Poloniae

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2019

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Vol. 89, No. 2

121--152

EN

Thermal maturity modelling was carried out in over sixty wells along the SW margin of the East European Craton (EEC). The burial and thermal history modelling of the EEC, using thermochronological data, allowed the construction of burial history maps showing its geological development in the Phanerozoic. These results have proved that the Ordovician and Silurian source rocks occurring at the SW margin of the EEC reached a maximum palaeotemperature in the Palaeozoic, mainly during Devonian-Carboniferous time and at the latest during the Silurian in the most westerly part of this margin, along the Teisseyre-Tornquist Zone. In Mesozoic and Cainozoic time, the Ordovician and Silurian strata generally were subjected to cooling or to very minor heating, certainly below the Variscan level. The maximum burial and maximum temperature of the Ediacaran-Lower Palaeozoic strata were reached during the Early Carboniferous in the Baltic Basin and during the Late Carboniferous in the Lublin area, and even in the Early Permian in the SE corner of the Lublin Basin. Thus, the main period of maturation of organic matter and hydrocarbon generation in the Ordovician and Silurian source rocks was in the Late Palaeozoic (mainly Devonian-Carboniferous) and in the westernmost zone along the Teisseyre-Tornquist line at the end of the Silurian.

16

Rock physics modelling for determination of effective elastic properties of the lower Paleozoic shale formation, North Poland

Wawrzyniak-Guz Kamila

Acta Geophysica

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2019

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Vol. 67, no. 6

1967--1989

EN

This paper presents an application of rock physics templates constructed with the use of the granular effective medium theory and the shale model to estimate the elastic properties of the Silurian and Ordovician shale formations from the Baltic Basic, Poland. The author uses available logging data from three nearby wells and their petrophysical interpretation to distinguish various lithologies and to determine average matrix mineral composition of each lithology group, essential in further rock physics modelling. Anisotropy estimation and investigation of the relation between various petrophysical parameters precede the rock physics modelling. The logging data cross-plotted in Vp/Vs/ ratio–acoustic impedance domain reveals distinct compaction trend for shales, which is not followed by shales with increased organic matter and calcareous deposits. These two lithology groups present own trends, which are related to increasing kerogen and carbonate minerals contents, respectively. The trends are the subject of rock physics modelling. Granular effective medium rock physics templates are constructed for each lithology group. The rock physics analyses reveal that the elastic properties of strongly compacted shales, including shales with organic matter, might be successfully described by the lower modified Hashin–Shtrikman bound, which is useful in compaction trend modelling. Marly deposits can be modelled in a similar way to shales. The upper modified Hashin– Shtrikman bound provides a better template for carbonates as it models the cementation process. The shale model provides independent rock physics template for shales. Comparison of these two approaches shows that the granular effective medium method better describes the elastic properties of the analysed formations. The paper includes also the proposition of the final rock physics template constructed for the Silurian and the Ordovician formation from the Baltic Basin that can contribute to a better understanding of the elastic properties of the lower Paleozoic shale plays in Poland.

17

Estimation of the quality factor based on the microseismicity recordings from Northern Poland

Wandycz Paweł, Święch Eryk, Eisner Leo, Pasternacki Andrzej, Wcisło Miłosz, Maćkowski Tomasz

Acta Geophysica

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2019

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Vol. 67, no. 6

2005--2014

EN

We use the peak frequency method to estimate effective P- and S-wave quality factors (QP and QS) based on the recorded waveforms of microseismic events. We analyze downhole datasets recorded during the hydraulic stimulation of the two unconventional gas reservoirs located in the northern part of Poland. The effective attenuation is lower in the deeper reservoir consistent with higher compaction. In both cases, we observe high QS values relative to QP which is consistent with attenuation coefficients of saturated reservoirs.

18

Baseline groundwater monitoring for shale gas extraction: definition of baseline conditions and recommendations from a real site (Wysin, Northern Poland)

Montcoudiol N., Banks D., Isherwood C., Gunning A., Burnside N.

Acta Geophysica

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2019

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Vol. 67, no. 1

365--384

EN

Public concerns have been raised regarding the use of hydraulic fracturing for shale gas extraction and its potential impact on the environment. The absence of baseline monitoring data in the US experience has been identified as a major issue. Here, results from a 6-month groundwater baseline monitoring study near an active shale gas pad in northern Poland are presented. The data collected in dedicated boreholes include groundwater samples analysed for inorganic constituents, dissolved gases and stables isotopes (δ2H and δ18O) and downhole temperature and conductivity measurements at 15-min intervals. A robust statistical analysis combined with an estimation of data uncertainty helps to identify spatial and temporal variability within the datasets. As a result, baseline conditions are defined using confidence intervals around the mean on a per-well basis and these will serve for future reference for this site. The groundwater chemical composition is similar to regional background levels and typical of Quaternary aquifers in the region. It is also consistent with previous baseline monitoring carried out by the Polish Geological Institute. Only manganese and bromide occur in groundwater at concentrations above Polish drinking water standards. Based on this work, the paper provides some recommendations for future baseline monitoring and identifies areas for future research such as use of statistics for high-frequency datasets.

19

Origin and significance of early-diagenetic calcite concretions and barite from Silurian black shales in the East European Craton, Poland

Bojanowski Maciej J., Kędzior Artur, Porębski Szczepan J., Radzikowska Magdalena

Acta Geologica Polonica

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2019

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Vol. 69, no. 3

403--430

EN

The Silurian Pelplin Formation is a part of a thick, mud-prone distal fill of the Caledonian foredeep, which stretches along the western margin of the East European Craton. The Pelplin Formation consists of organic carbon-rich mudstones that have recently been the target of intensive investigations, as they represent a potential source of shale gas. The Pelplin mudstones host numerous calcite concretions containing authigenic pyrite and barite. Mineralogical and petrographic examination (XRD, optical microscopy, cathodoluminoscopy, SEM-EDS) and stable isotope analyses (δ13Corg, δ13C and δ18O of carbonates, δ34S and δ18O of barite) were carried out in order to understand the diagenetic conditions that led to precipitation of this carbonate-sulfide-sulfate paragenesis and to see if the concretions can enhance the understanding of sedimentary settings in the Baltic and Lublin basins during the Silurian. Barite formed during early diagenesis before and during the concretionary growth due to a deceleration of sedimentation during increased primary productivity. The main stages of concretionary growth took place in yet uncompacted sediments shortly after their deposition in the sulfate reduction zone. This precompactional cementation led to preferential preservation of original sedimentary structures, faunal assemblages and earlydiagenetic barite, which have been mostly lost in the surrounding mudstones during burial. These components allowed for the reconstruction of important paleoenvironmental conditions in the Baltic and Lublin basins, such as depth, proximity to the detrital orogenic source and marine primary productivity. Investigation of the concretions also enabled estimation of the magnitude of mechanical compaction of the mudstones and calculation of original sedimentation rates. Moreover, it showed that biogenic methane was produced at an earlydiagenetic stage, whereas thermogenic hydrocarbons migrated through the Pelplin Formation during deep burial.

20

A possible application of rotary-percussion drilling method in shale gas wells in the Podlasie Basin region

Śliwa T., Korzec M., Jaszczur M., Sapińska-Śliwa A., Gajdosz A., Kruszewski M.

Technika Poszukiwań Geologicznych

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2018

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R. 57, nr 2

197--222

EN

The following work presents investigation of possible drilling of overburden rocks, right above the gas reservoir, in shale rock formations with potential application of rotary-percussion drilling method in Podlasie Basin region. Extensive description of lithology of shale rocks together with their age, maturity of the organic matter and thickness of particular layers have been presented. Due to different thickness of formations, the depths of layers are not indicated, as it would be too big of approximation. Variously scaled and averaged thickness of particular formation layers was given in order to maintain maximum transparency of the paper. It should be noted that the formation rocks of the Devonian as well as Carboniferous period do not occur in all profiles of the Paleozoic period of the Podlasie Basin but only in the south-western part of the basin. Locally occurring (i.e. on the south-eastern border of the Podlasie basin) layers of the Devonian and Carboniferous period were omitted. A stratigraphic profile with preserved proportions between the average thicknesses of particular formation layers was constructed and presented in latter part of the research paper. The research carried out in this paper was complemented with estimates of Polish shale gas resources. The Baltic Basin region is by far most prospective area for shale gas exploitation when it comes to documented as well as undocumented resources. The areas of Podlasie as well as Lublin Basins are second and third most rich areas of this resource. Percussion-rotary drilling method enables for much higher penetration rates using similar weight on bit and rotational speed as in standard rotary drilling method. Following papers answers questions such as: under what conditions application of percussion-rotary technique is possible or what drilling fluids are the most suitable for such method. The percussion-rotary drilling method not only guarantees faster drilling but also leaves borehole much more straight and without unnecessary dog legs. Drilling rig and down hole equipment used for percussion-rotary drilling method takes much less space in comparison with standard rotary rigs for deep drilling and could be potentially implemented for drilling shale gas wells in Podlasie Basin region.

PL

Poniższa praca przedstawia badania nad potencjalnym wykorzystaniem metody udarowo-obrotowej w celu wiercenia formacji skalnych występujących tuż nad pokładami złóż gazu łupkowego w rejonie basenu podlaskiego. W poniższym artykule została przeprowadzona analiza skał łupkowych wraz z ich wiekiem, dojrzałością materii organicznej oraz miąższością poszczególnych warstw. Na skutek dość zróżnicowanej miąższości formacji skalnych, głębokość zalegania warstw nie została określona z powodu dużego błędu przy uśrednieniu ich wartości. Wyskalowane oraz uśrednione miąższości zostały przedstawiono w celu utrzymania spójności i przejrzystości pracy. Należy nadmienić, że formacje skalne z okresu dewońskiego oraz karbońskiego nie występują we wszystkich profilach z okresu paleozoiku basenu podlaskiego, a jedynie w jego południowo-zachodnich częściach. Pominięto lokalnie występujące (tj. na południowo-wschodniej granicy) warstwy dewońskie oraz karbońskie. Profil litostratygraficzny z zachowanymi proporcjami pomiędzy średnimi miąższościami poszczególnych warstw skalnych został skonstruowany oraz przedstawiony w końcowej części pracy. Badania w poniższym artykule zostały dodatkowo uzupełnione danymi szacunkowymi zasobów gazu łupkowego na terenie Polski. Obszar basenu bałtyckiego jest obecnie najbardziej lukratywny pod względem wydobycia gazu ze skał łupkowych z powodu dużej ilości udokumentowanych oraz jeszcze nierozpoznanych złóż tego surowca. Obszary basenu podlaskiego oraz lubelskiego są drugie oraz trzecie w kolejności pod względem ilości zasobów gazu łupkowego na terenie Polski. Metoda udarowo-obrotowa pozwala na dużo szybsze zwiercanie formacji skalnych przy użyciu podobnych parametrów mechanicznych takich jak nacisk na świder i prędkość obrotowa niż przy standardowym procesie wiercenia metodą obrotową. Poniższy artykuł odpowiada na pytania takie jak: w jakich warunkach możliwe jest wiercenie metodą udarowo-obrotową oraz jakie rodzaje płuczek wiertniczych są najbardziej odpowiednie do wiercenia taką techniką. Metoda udarowo-obrotowa zapewnia nie tylko dużo większy postęp wiertniczy, ale również dużo mniejsze odchylenia od osi otworu oraz zapobiega nagłym zmianom kierunku podczas procesu wiercenia. Wiertnica oraz osprzęt zapuszczany do otworu stosowany podczas wiercenia metodą udarowo-obrotową zajmuje znacznie dużo mniej miejsca w porównaniu z głębokimi wierceniami konwencjonalnymi metodami. Dzięki wspomnianym zaletom metoda udarowo-obrotowa może zostać potencjalnie wykorzystana przy wierceniu otworów za gazem łupkowym w obszarze basenu podlaskiego.