Lublin Basin Research Articles

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

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. Poorto 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.

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

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.

Ordovician–Silurian lithostratigraphy of the East European Craton in Poland

This paper deals with the lithostratigraphic correlation of the Ordovician–Silurian succession between the Baltic, Podlasie and Lublin basins, located on the SW slope of the East European Craton. The correlation is based on previous lithostratigraphic classifications, which are modified here to include the results of recent biostratigraphic and sedimentological work performed on several new wells. The authors propose to extend the Sasino Formation for the entire upper Darriwilian–lower Katian mudstone sheet that is traceable in all basins. It is recommended that the Jantar Bituminous Claystone Member (late Hirnantian–Aeronian) of the Paslek Formation be elevated to the rank of formation and the name Paslek Mudstone Formation be retained for the late Aeronian–Telychian, rhythmic alternations of black, laminated mudstones and greenish, bioturbated mudstones. Moreover, the authors suggest that the top of the Kociewie Formation (Sheinwoodian–Ludfordian) be placed at the upper boundary of the Reda Member (latest Ludfordian), which shows much wider lateral persistence than previously was thought.

Late Carboniferous thin-skinned deformation in the Lublin Basin, SE Poland: Results of combined seismic data interpretation, structural restoration and subsidence analysis

The aim of this study was to investigate the factors, which controlled the lateral change of structural style in the southeastern part of the Lublin Basin (Poland). Five selected seismic reflection profiles were interpreted with a focus on structural interpretation. Along the representative seismic reflection profile, a geological cross-section was constructed and restored. The structural model was supplemented/refined with core analysis to characterize the deformation mode affecting Silurian strata at a sub-seismic scale (i.e. below the seismic vertical resolution). Published palaeothickness maps were used to estimate the pre-deformation thickness of partly eroded Carboniferous rocks. The results of cross-section restoration were then compared to the subsidence modelling carried out for one deep well. The study revealed that during Late Carboniferous shortening, a thick layer of Silurian shales played the role of detachment level, above which brittle Devonian–Carboniferous strata were folded and thrust. The lateral extent of thin-skinned deformation was controlled by the presence of a step in the basement and the pinching out of the Silurian strata. In the northwestern part of the Lublin Basin, the Kock Fault Zone acted as a region of strain concentration, where Silurian shales were tectonically thickened, and shows a ductile style of deformation resembling the mushwad structures of the Appalachian fold-and-thrust belt.

Graptolite biostratigraphy and dating of the Ordovician–Silurian shale succession of the SW slope of the East European Craton

This paper deals with the graptolite biostratigraphy and age determination of the Ordovician and Silurian lithological successions of the Baltic, Podlasie and Lublin basins that existed during the early Palaeozoic on the SW slope of the East European Craton. The biostratigraphic research described was conducted on core material coming from old boreholes and cores from several new wells. Graptolite zones were identified and the chronostratigraphic succession was constrained, with the depths to the stratigraphic units, especially those considered prospective for petroleum, being determined in the individual borehole sections. Old local stratigraphic schemes of the Silurian used for many years in the Polish geological literature are correlated with the standard schemes. The most complete succession of graptolite zones, both in the Ordovician and the Silurian, is observed in the Baltic region. The number of stratigraphic gaps increases towards the east and southeast of the regions. The stratigraphic range of the Sasino Shale Formation decreases in this direction; in the Podlasie and Lublin regions, it comprises only the Katian Stage. The stratigraphic range of the Jantar Formation in the western part of the area spans not only the Rhuddanian but also part or the whole of the Aeronian. In the Podlasie and especially the Lublin regions, sedimentation of the Jantar Formation began in the latest Rhuddanian–Aeronian. A large stratigraphic gap, spanning part or the whole of the Llandovery and increasing eastwards, was documented in the Podlasie-Lublin region. The biostratigraphic research allowed a more precise constraint on the temporal and spatial extent of erosion of Pridoli deposits and the beginning of coarse-grained, siliciclastic sedimentation (Kociewie Formation) in the Baltic Basin.

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

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.

Fracture pattern of the Lower Paleozoic sedimentary cover in the Lublin Basin of southeastern Poland derived from seismic attribute analysis and structural restoration

We have characterized Late Devonian fracture systems in the northeastern part of the Lublin Basin in Poland using two independent approaches: (1) seismic data conditioning and volumetric attribute analysis and (2) structural restoration, geomechanical modeling, and fracture modeling. The study area was subjected to reverse faulting in the basement and fault-related folding at the end of Devonian. These late Devonian structures were not overprinted by later deformation events. We have applied a set of structurally oriented filters and seismic attributes aimed at highlighting discontinuities to reduce the seismic noise and improved the fracture visibility on structural steering volume. The main faults cutting intra-Neoproterozoic and intra-Ordovician horizons are principal east–west-striking reverse faults and minor northwest–southeast-oriented normal faults. Based on analysis of the seismic-scale faults, we have carried out fracture modeling for strike-slip and compressional stress fields, with a northwest–southeast-oriented axis of maximum compression. We have correlated tentative strikes for tensile, shear, and closing-mode fractures for both stress regimes, with fault-likelihood attribute maps. The observed fracture system can have developed in the strike-slip stress regime, although cracks generated due to gas overpressure, or of pre-Devonian age, are not excluded. The final fracture model may be extrapolated into Silurian strata, but the results should be perceived as a general approximation of structural trends due to significant differences in mechanical properties of Silurian shales and underlying Ordovician carbonates. Improved model calibration could be achieved after inspection of scanner image logs. We believe that understanding the fracture distribution within the gas-bearing Silurian strata may contribute to effective planning and performing of hydraulic fracturing because part of these fracture planes may be reopened and provide new conduits for fluid flow.

Tectono-thermal Evolution of the Lower Paleozoic Petroleum Source Rocks in the Southern Lublin Trough: Implications for Shale Gas Exploration from Maturity Modelling

The Lower Paleozoic basins of eastern Poland have recently been the focus of intensive exploration for shale gas. In the Lublin Basin potential unconventional play is related to Lower Silurian source rocks. In order to assess petroleum charge history of these shale gas reservoirs, 1-D maturity modeling has been performed. In the Łopiennik IG-1 well, which is the only well that penetrated Lower Paleozoic strata in the study area, the uniform vitrinite reflectance values within the Paleozoic section are interpreted as being mainly the result of higher heat flow in the Late Carboniferous to Early Permian times and ~3500 m thick overburden eroded due to the Variscan inversion. Moreover, our model has been supported by zircon helium and apatite fission track dating. The Lower Paleozoic strata in the study area reached maximum temperature in the Late Carboniferous time. Accomplished tectono-thermal model allowed establishing that petroleum generation in the Lower Silurian source rocks developed mainly in the Devonian – Carboniferous period. Whereas, during Mesozoic burial, hydrocarbon generation processes did not develop again. This has negative influence on potential durability of shale gas reservoirs.

A record of Late Ordovician to Silurian oceanographic events on the margin of Baltica based on new carbon isotope data, elemental geochemistry, and biostratigraphy from two boreholes in central Poland

New stable isotope data from organic carbon (δ13Corg) and inorganic elemental geochemistry data have been generated from Upper Ordovician to Silurian strata in two boreholes in the Lublin Basin of Poland: Grabowiec-6 and Zwierzyniec-1. They have been integrated here with biostratigraphical data from graptolites, acritarchs, and chitinozoans. Faunal assemblages from Grabowiec-6 indicate that it spans from the Katian (clingani graptolite Biozone) to the Gorstian (scanicus graptolite Biozone); δ13Corg values from this section record the Sheinwoodian Ireviken Excursion, the Homerian Mulde Excursion, and a minor positive shift associated with the lower Ludfordian leintwardinensis Biozone. The second section, Zwierzyniec-1, spans the Sandbian through Gorstian (nilssoni Biozone); δ13Corg values record the Hirnantian carbon isotope excursion (HICE) and the Ireviken Excursion as well.Elemental geochemistry data is used to recognize subtle changes in provenance and lithology. Significant increases in the abundance of V and Mo are recognized in strata deposited above the Ireviken Excursion. The enrichment of these redox sensitive elements suggests that persistent regional anoxia and euxinia may be associated with the aftermath of these oceanographic disturbances. Some of these same trace elements, along with Fe2O3, and Pb are also abundant in strata coeval with, or just below the Ireviken and HICE excursions. This may have a causal link with malformed palynomorphs observed at these intervals by some workers, which are thought to reflect toxic levels of dissolved heavy metals in the world's oceans.

Multi-scale 3D characterisation of porosity and organic matter in shales with variable TOC content and thermal maturity: Examples from the Lublin and Baltic Basins, Poland and Lithuania

Understanding the distribution of pores and organic matter with varying organic matter concentrations and maturity is essential to understanding fluid flow in shale systems. Analysis of samples with low, medium, and high total organic carbon (TOC) and varying maturities (gas-mature and oil-mature) enables the impact of both organic matter concentrations and thermal maturation on organic matter porosity to be examined. Three gas-mature samples of varying TOC (Lublin Basin) and one oil-mature sample (Baltic Basin), both with similar mineral compositions, were selected from the same formation. Samples were imaged in 3D over four orders of magnitudes (pixel sizes from 44μm to 5nm). A combination of X-ray computed tomography (XCT) and Focus Ion Beam Scanning Electron Microscopy (FIB-SEM) enabled the morphologic and topological characteristics of minerals, organic matter and pores to be imaged and quantified.In the studied samples, organic matter primarily has two geometries: lamellar masses (length: 1–100μm, thickness: 0.5–2.0μm) and discrete spheroidal particles (0.5–20.0μm). Organic matter forms an inter-connected network where it exceeds a concentration between 6 and 18wt%.Different pore types have different diameters and total pore volumes: inter-mineral pores (0.2μm, 10–94%), organic interface pores (0.2μm, 2–77%), intra-organic pores (0.05μm, 1–40%) and intra-mineral pores (0.05μm diameter, 1–2% of total porosity). The major pore system in the studied shales is composed of inter-mineral pores which occur between clay mineral grains. TOC concentration influences the total volume of organic matter-related pores while maturity controls the presence of intra-organic pores. The study improves the understanding of the relationship of organic matter concentrations, maturity and pore systems in shales. This study characterises porosity and organic matter distributions in 3D; it also improves the understanding of the relationship of organic matter concentrations, maturity and pore systems in shales.

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)

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 NH 4 -rich illite of the clayey facies of the Ordovician–Silurian strata

Thermal methods implementation in analysis of fine-grained rocks containing organic matter

The thermal methods, including TG and DSC techniques, were implemented to determine the composition of the fine-grained rocks with dispersed organic matter. The analyses were carried out in inert and oxidising atmosphere. The analysed samples represented Palaeozoic siltstones, shales, claystones and mudstones from Baltic Basin, Lublin Basin and Upper Silesian Coal Basin (Poland). There was detected the presence of some minerals as: clay minerals, muscovite, quartz, calcite, dolomite and pyrite. A comparison of the reactions occurring in an oxidising and inert atmosphere can give a solution to the problem of some effects overlapping, such as distinguishing pyrite decomposition from organic matter combustion. The analysis of DSC curves of heated rocks under oxidative atmosphere allows to determine the temperature regions of the organic matter combustion and to conclude on its maturity level. There was also found a strong correlation between the mass loss resulted from organic matter combustion, and the mass loss as a result of pyrolysis.

Feasibility Analysis of Groundwater Abstraction for Gas Shale Fracturing in the Lublin Basin (Eastern Poland) / Ocena Możliwości Poboru Wód Podziemnych Do Szczelinowania Łupków Gazonośnych W Basenie Lubelskim (Wschodnia Polska)

Abstract Natural gas extraction from shale rock necessitates hydraulic fracturing of rocks, which involves large amounts of fracture fluids made of 90.5% of water. The authors focus on feasibility of groundwater abstraction for the purpose of applying fracture fluids in wells of the Lublin Basin - area of perspective unconventional gas exploitation from the Ordovician and the Silurian shales. These data refer to the expected specific capacity of wells abstracting groundwater from main useful aquifers. Specific capacity of a well (q) belongs to high-certainty empirical parameters, characterizing water-bearing capacity of rocks at a regional scale. The spatial evaluation of q was based on respective data coming from 7 sheets of the Hydrogeological Map of Poland (scale 1:200,000) covering research area. Specific capacity q was calculated for wells abstracting water from the Upper Cretaceous, Tertiary and Quaternary aquifers in areas presented on particular sheets of the map. Authors determined the variability distribution and the cumulative probability plots of q values, indicating a range which corresponded to a sum of standard deviation (SD) above and below median (X̄), i.e. X̄ ± 1SD. On the total the interval included 68.2% of data. The results reveal that 0.6 ≤ q ≤ 40 m3h-1 per 1 meter of drawdown for the Upper Cretaceous rocks in the eastern part of the area, and 1.1 ≤ q ≤ 110 m3h-1 per 1 meter in the western part, being a result of more intense fracturing and fissuring. Owing to the scarcity of data, q values of wells screened at the Tertiary and Quaternary aquifers are given jointly for the whole area: 0.8 ≤ q ≤ 20 and 1.0 ≤ q ≤ 10 m3h-1 per 1 meter, respectively. The obtained specific capacities are high. When the wells are properly designed, their discharges may reach about ca. 100 m3h-1.

Tournaisian 40Ar/39Ar age for alkaline basalts from the Lublin Basin (SE Poland)

The main aim of this study is to define precisely the age of the alkaline basalts occurring within the lowermost part of Carboniferous succession in the northeastern part of LublinBasin(drill core Parczew IG-7 and IG-9; SE Poland). The new, whole-rocks 40 Ar/ 39 Ar data constrain the age of volcanic activity and emplacement of alkaline basalts to the Late Tournaisian (348 ± 0.8 Ma) with possible prolongation to the Middle Visean (338.5 ± 0.7 Ma). The younger age is however of evidently poorer quality than the older one. The new data caused to correlate the volcanic processes occurring within theLublinBasin with alkaline intrusions drilled inNE Poland inside the Paleozoic cover of the East European Platform. They also correspond to the volcanoclastic levels defined in different parts of the Trans European Suture Zone inPoland.

Serpukhovian (Early Carboniferous) Rugosa (Anthozoa) from the Lublin Basin, eastern Poland

Sixteen rugose coral species, two known previously, nine new, three left in open nomenclature, and two identified as affinis , are described from the early Serpukhovian strata of the Lublin area, eastern Poland. Rugose corals of that age here are described for the first time from Poland. New genera include Birkenmajerites , Chelmia and Occulogermen . New species include: Axisvacuus tenerus , Birkenmajerites primus , Chelmia radiata , Nervophyllum lukoviensis , Occulogermen luciae , Rotiphyllum plumeum , ? Sochkineophyllum symmetricum , Zaphrentites rotiphylloides and, Zaphrufimia anceps . A brief analysis of the taphonomy, possible relationships and geographical connections of the corals described here to rugose coral faunas from adjacent areas also is included.

Assessment of disposable groundwater resources for hydraulic fracturing of gas shales in the Lublin Basin (eastern Poland)

Streszczenie W pracy dokonano prognozy zasobów wód podziemnych do wykorzystania w celu szczelinowania łupków gazonośnych w obszarze Basenu Lubelskiego w 2030 r. Jest to przydatne właścicielom koncesji na eksploatację gazu do planowania wielkości i harmonogramu wydobycia. W celu określe- nia dyspozycyjnych zasobów wód opracowano model bilansu wodno-gospodarczego, do którego jako podstawowe dane wejściowe wykorzystano dane z bilansu i prognozy zasobów wód podziemnych dla 2030 r. w dorzeczu Wisły. W modelu uwzględniono specyficzne czynniki determinujące wielkość zasobów wody na obszarach perspektywicznej eksploatacji gazu: zmniejszenie zasilania wód pod- ziemnych w wyniku zmian klimatu, nierejestrowany pobór wody w gospodarstwach indywidualnych, zapotrzebowanie na wodę związane z rozwojem górnictwa gazu łupkowego i stopnień zwrotu do obiegu hydrologicznego wody, wykorzystanej do szczelinowania. W celu uwzględnienia niepewności stopnia oddziaływania tych czynników w 2030 r., model wykonano dla dwóch scenariuszy: umiar- kowanie rygorystycznego ekologicznie i rygorystycznego ekologicznie, zakładającego duże skutki zmian klimatu i radykalne zwiększenie zapotrzebowania na wodę. Zasoby dyspozycyjne wód okreś- lono dla wydzielonych 12 stref bilansowych, zgodnych obszarowo z Jednolitymi Częściami Wód Podziemnych lub ich fragmentami znajdującymi się w obszarze badań. Prognoza dotyczy zasobów wód podziemnych bez stratygraficznego rozdziału na poziomy wodonośne. Zasoby wyniosą dla scenariusza I od 1 072 735 do 79 458 310 m3/rok w zależności od strefy. Dla scenariusza II odpo- wiednio od 733 285 do 49 103 085 m3/rok. Dla właścicieli koncesji na eksploatację gazu istotne są względne wartości zasobów wyrażone na jednostkę powierzchni, które wyniosą dla scenariusza I od 10 132 do 32 300 m3/(rok-km2) w zależności od strefy i dla scenariusza II od 5 212 do 24 200 m3/(rok-km2). Model bilansowy pozwala stwierdzić, że prognozowane na 2030 r. zasoby dyspozycyjne wód podziemnych w strefach bilansowych Basenu Lubelskiego są duże, więc rozwój górnictwa gazu łupkowego nie powinien wpłynąć negatywnie na stan ilościowy wód w tym obszarze.

Carboniferous tetrapod footprints from the Lublin Basin, SE Poland

Evidence of tetrapod footprints is scarce in the Carboniferous rocks of Europe and only a dozen sites have been found. Here is presented the first description of the Carboniferous tetrapod traces collected from the Bogdanka Coal Mine, Lublin Basin, south-eastern Poland. The footprints occur in reddish, white-gray sandstone or black-brown siltstone-mudstone, fluvial and lacustrine in origin, of the Westphalian A and B (about 315 and 310 Ma, lower-middle Pennsylvanian) of the Lublin Formation. Based on the study of 19 specimens (isolated and usually poorly preserved manus or pes imprints), I discern two distinct types of tetrapod footprints and also problematic traces (or scratches) made by swimming tetrapods. Footprints are assigned to the two ichnotaxa: Batrachichnus–Limnopus plexus and aff. Pseudobradypus isp. Traces described as Tetrapoda indet. A–C represent poorly preserved footprints, which are similar to the ichnogenera Ichniotherium, Dimetropus and Attenosaurus. The described trace fossils were produced by small amphibians (temnospondyls) and medium-sized amniotes (reptiliomorphs and reptiles). The tetrapod ichnofauna from the Bogdanka Coal Mine is similar in composition to Pennsylvanian ichnofaunas from Europe and North America.

Carboniferous coarsening-upward and non-gradational cyclothems in the Lublin Basin (SE Poland): palaeoclimatic implications

Abstract The paper presents the characteristics of profiles consisting of coarsening-upward and non-gradational cyclothems that correspond to parasequences in the Visean, Serpukhovian and Bashkirian sections of the Lublin Basin in SE Poland. The accompanying single fining-upward cyclothems are also described. Six types of cyclothems are distinguished. The most complete types of coarsening-upward cyclothems Ic, Id and incomplete IIc and IId have been identified. The least complete are non-gradational cyclothems IIIc and IIId. The cyclothems developed within the oscillating environments of shallow carbonate and clay shelf, and in shallow-water deltas. The lowstand systems tract (LST) deposits are composed of fining-upward cyclothems, rarely of coarsening-upward IId and non-gradational IIId. Within the transgressive systems tract (TST), type IIc is dominant, and the quantity of Ic and non-gradational cyclothem IIIc is moderate. The maximum flooding surface (MFS) usually occurs within coarsening-upward cyclothems IIc. The highstand systems tract (HST) consists of similar types of cyclothems as the TST, but their quantity is less. Relative sea-level fluctuations during the Carboniferous deposition in the Lublin Basin are associated with sea-level changes generated by glacial episodes in Gondwana. The relative sea-level fluctations also affected both erosional processes related to the successive relative sea-level lowstands and the formation of stratigraphic gaps. The influence of glacio-eustatic fluctuations was modified by local factors such as the supply of sedimentary material, subsidence rate and local tectonics.

Braided-river and hyperconcentrated-flow deposits from the Carboniferous of the Lublin Basin (SE Poland) – a sedimentological study of core data

Abstract Fining-upwards cyclothems found in five boreholes in the Carboniferous (Lower Bashkirian) of the Lublin Basin were analysed sedimentologically. It was established that the cyclothems represent fluvial deposits, and the lithofacies were grouped into lithofacies associations. Most lithofacies associations represent three types of sand-bed braided rivers: (1) high-energy, (2) deep and (3) distal sheetflood-affected. Other associations represent hyperconcentrated flows. Both coarse-grained (type I) and fine-grained (types IIa and IIb) occur among the fining-upward cyclothems. The formation of most thick cyclothems was related mainly to allocyclic factors, i.e. a decrease in the river’s gradient. The thickest fining-upward cyclothems are characteristic of hyperconcentrated flows and braided-river channels. The aggradation ratios were commonly high. During the early Namurian C and early Westphalian A (Early Bashkirian), the eastern part of the Lublin Basin was located close to the source area. The sedimentary succession developed due to a transition from high-energy braidedrivers and hyperconcentrated flows to lower-energy braided rivers, controlled by a rise of the regional base level.

Europe Gears Up for the Shale Gale

The European shale gas revolution is still in its infancy and though its commercial potential could rival that of North America, significant challenges lie ahead. France has put a moratorium on shale gas activity while a comprehensive study into its environmental impact is being carried out, and its National Assembly has voted in favor of a ban on hydraulic fracturing. The potential for shale gas production in Europe is undoubted, as consultancy IHS CERA estimates that Europe’s total shale gas in place could be 6,115 Tcf. Among the key challenges that will determine the ultimate productivity in Europe is a regulatory environment that is currently ill-suited to unconventional gas, the company said. “Regulations designed for traditional exploration and production in Amsterdam. “We expect Europe to be a significant part of future activity.” Poland Leads the Way Poland plays host to Europe’s largest known reserves of shale gas. Leasing activity in the country’s three main basins—the Baltic Basin, the Podlasie Basin in the east, and the Lublin Basin to the south—is well under way. The country is keen to push forward with shale gas production as it looks to break away from its reliance on Russian gas supplies. The US Energy Information Administration (EIA) estimates that Poland has 792 Tcf of risked shale gas in place, with 514 Tcf in the Baltic Basin, 222 Tcf in the Lublin Basin, and the remainder in the Podlasie Basin. Chevron and ExxonMobil have been joined by a large number of smaller players such as DPV Service, Cuadrilla, EUR Energy, and Mazovia Energy in securing acreage across the country. Talisman is carrying out seismic acquisition on con-cessions in the Baltic Basin and it is on track to spud its first two shale gas wells in the fourth quarter of this year, the company said. It moved into the Polish plays through a farm-in arrangement with San Leon Energy for a 60% interest in San Leon’s three concessions. Talisman is committed to drilling a minimum of three wells—Gdansk-W, Braniewo-S, and Szczawno—which cover 600,000 acres. Three optional wells with horizontal sections will be drilled after a successful first phase of testing. San Leon is also engaged in a five-year exploration and development program on its two concessions, Nowa Sol and Wschowa in the Permian Basin South. Both concessions are on trend with prolific Rotliegendes gas and Zechstein oil production. Nexen recently entered into an agreement with Marathon to jointly explore 10 concessions in Poland’s Paleozoic shale play and it says it will pump USD 100 million into shale-related activities. Nexen will acquire a 40% working interest in the concessions, which encompass more than 2 million acres. Marathon is acquiring 2D seismic this year and plans to drill one or two wells in the fourth quarter and potentially seven or eight wells during 2012.