Tectonic factors affecting coal bed methane distribution in the Donets basin

Донецький басейн є найбільшим вугледобувним регіоном України. Вугільні копальні Донбасу - серед найбільш небезпечних за газовим фактором у світі. Більшість шахт басейну працює у межах тектонічних блоків з широким розвитком зон малоамплітудної тектонічної порушеності зсувного генезису. Спеціальну увагу має бути приділено аналізу локальних структурно-тектонічних режимів, що впливають на розподіл метану і оцінку його ресурсів. Проникність вуглепородного масиву та варіації просторового розподілу метанових покладів зумовлені сучасним розподілом полів тектонічних напружень та насамперед локалізацією ділянок локального розтягу-стиску. Нашими дослідженнями встановлено, що так звані «солодкі ділянки» з видобутку метану просторово тяжіють до доменів з відносно великою проникністю, котрі розвиваються у межах секторів призсувного розтягу (дилатаційного розущільнення) в контурі зсувних зон.Донецкий бассейн является наибольшим угледобывающим регионом Украины. Угольные шахты Донбасса - среди наиболее опасных по газовому фактору в мире. Большинство шахт бассейна работает в пределах тектонических блоков с широким развитием зон малоамплитудной тектонической нарушенности сдвигового генезис. Специальное внимание должно быть уделено анализу локальных структурно-тектонических режимов, которые влияют на распределение метана и оценку его ресурсов. Проницаемость углепородного массива и вариации пространственного распределения метановых залежей обусловлены современным распределением полей тектонических напряжений и в первую очередь локализацией участков локального растяжения-сжатия. Нашими исследованиями установлено, что так называемые «сладкие участки» по добыче метана пространственно тяготеют к доменам с относительно большой проницаемостью, которые развиваются в пределах секторов присдвигового растяжения (дилатационного разуплотнения) в контуре зон сдвиговых зон

Maturation and isotopic changes of individual hydrocarbons in lignite lithotypes through diagenesis and early catagenesis

Maturation and isotopic changes of individual hydrocarbons in lignite lithotypes through diagenesis and early catagenesis were studied. The maturity ratios based on biomarkers and alkylaromatics which showed the best applicability were determined. Intensity of observed changes of maturity ratios decreases in the following order: mineral-rich coal > matrix coal > xylite-rich coal, indicating that mineral matter, which is dominated by clays in all lithotypes, plays an important role in the isomerisation of polycyclic biomarkers and aromatic compounds. Carbon isotopic signatures of n-C25 and n-C27 alkanes, as well as δ13C values of phenathrene and cadalene are very close in studied range of maturity, confirming that isotopic signatures are useful tracers for alteration products of biological molecules. Long-chain homologues of n-alkanes exhibit slight enrichment in 12C with increasing maturity, whereas almost no change is detected in δ13C of short-chain n-alkanes. Negligible enrichment in 13C of aromatic compounds is observed during maturation

Petrographical and biomarker study of lignite lithotypes and sublithotypes of xylite-rich coal (Kolubara Basin, Serbia)

Invited lectur

Ziyapaş kadın

Amédé Victor Guillemine'in Hizmet'te yayımlanan Ziyapaş Kadın adlı romanının ilk ve son tefrikalarıTefrikanın devamına rastlanmamış, tefrika yarım kalmıştır

Oceanic response to Pliensbachian and Toarcian magmatic events: Implications from an organic-rich basinal succession in the NW Tethys

The Bächental bituminous marls (Bächentaler Bitumenmergel) belonging to the Sachrang Member of the Lower Jurassic Middle Allgäu Formation were investigated using a multidisciplinary approach to determine environmental controls on the formation of organic-rich deposits in a semi-restricted basin of the NW Tethys during the Early Jurassic. The marls are subdivided into three units on the basis of mineralogical composition, source-rock parameters, redox conditions, salinity variations, and diagenetic processes. Redox proxies (e.g., pristane/phytane ratio; aryl isoprenoids; bioturbation; ternary plot of iron, total organic carbon, and sulphur) indicate varying suboxic to euxinic conditions during deposition of the Bächental section. Redox variations were mainly controlled by sea-level fluctuations with the tectonically complex bathymetry of the Bächental basin determining watermass exchange with the Tethys Ocean. Accordingly, strongest anoxia and highest total organic carbon content (up to 13%) occur in the middle part of the profile (upper tenuicostatum and lower falciferum zones), coincident with an increase in surface-water productivity during a period of relative sea-level lowstand that induced salinity stratification in a stagnant basin setting. This level corresponds to the time interval of the lower Toarcian oceanic anoxic event (T-OAE). However, the absence of the widely observed lower Toarcian negative carbon isotope excursion in the study section questions its unrestricted use as a global chemostratigraphic marker. Stratigraphic correlation of the thermally immature Bächental bituminous marls with the Posidonia Shale of SW Germany on the basis of C27/C29 sterane ratio profiles and ammonite data suggests that deposition of organic matter-rich sediments in isolated basins in the Alpine realm commenced earlier (late Pliensbachian margaritatus Zone) than in regionally proximal epicontinental seas (early Toarcian tenuicostatum Zone). The late Pliensbachian onset of reducing conditions in the Bächental basin coincided with an influx of volcaniclastic detritus that was possibly connected to complex rifting processes of the Alpine Tethys and with a globally observed eruption-induced extinction event. The level of maximum organic matter accumulation in the Bächental basin corresponds to the main eruptive phase of the Karoo-Ferrar large igneous province (LIP), confirming its massive impact on global climate and oceanic conditions during the Early Jurassic. The Bächental marl succession is thus a record of the complex interaction of global (i.e., LIP) and local (e.g., redox and salinity variations, basin morphology) factors that caused reducing conditions and organic matter enrichment in the Bächental basin. These developments resulted in highly inhomogeneous environmental conditions in semi-restricted basins of the NW Tethyan domain during late Pliensbachian and early Toarcian time

NEW GEOCHEMICAL INSIGHTS INTO CENOZOIC SOURCE ROCKS IN AZERBAIJAN: IMPLICATIONS FOR PETROLEUM SYSTEMS IN THE SOUTH CASPIAN REGION

The Maikop Group and the Diatom Formation constitute the two main source rocks in the South Caspian Basin and onshore Azerbaijan where large-scale oil production began more than 150 years ago. However, the stratigraphic distribution of the source rocks and the vertical variation of source-rock parameters are still poorly understood. The aim of the present paper is therefore to investigate in high resolution the source-rock distribution in the Perekishkyul and Islamdag outcrop sections, located 25 km NW of Baku, which provide nearly complete middle Eocene and lower Oligocene to upper Miocene successions. Bulk geochemical parameters of 376 samples together with maceral, biomarker and isotope data were analysed. In addition, new Re/Os data provide independent age dating for the base of the Upper Maikop Formation (30.0 ± 1.0 Ma) and the paper shale within the Diatom Formation (7.2 ± 2.6 Ma). The presence of steradienes in high concentrations demonstrates the thermal immaturity of the studied successions, limiting the application of some biomarker ratios. Intervals with high TOC contents and containing kerogen Type II occur near the top of the middle Eocene succession. However, because of the low net thickness, these sediments are not considered to constitute significant hydrocarbon (HC) source rocks. The Maikop Group in the Islamdag section is 364 m thick and represents lower Oligocene (upper Solenovian) to middle Miocene (Kozakhurian) levels. Samples are characterized by moderately high TOC contents (∼1.8 wt.%) but low hydrogen index (HI) values (average ∼120 mgHC/gTOC) despite a dominance of aquatic organic matter (diatoms, methanotrophic archaea and sulphate-reducing bacteria). Rhenium-osmium chronology suggests low sedimentation rates (∼25 m/Ma), which may have had a negative impact on organic matter preservation. Terrigenous organic matter occurs in variable but typically low amounts. If mature, the Maikop Group sediments at Islamdag could generate about 2.5 tHC/m2. The Diatom Formation includes a 60 m thick paper shale interval with high TOC contents (average 4.35 wt.%) of kerogen Type II-I (HI up to 770 mgHC/gTOC). The source potential is higher (∼3 tHC/m2) than that of the Maikop Group. The organic matter is dominated by algal material including diatoms. High TOC/S ratios suggest deposition under reduced salinity conditions. Strictly anoxic conditions are indicated by the presence of biomarkers for archaea involved in methane cycling. For oil-source correlations and a better understanding of the petroleum system, it will be necessary to distinguish oil generated by the Maikop Group from that generated by the Diatom Formation. This study shows that these oils can be distinguished based on the distribution of specific biomarkers e.g. C30 steranes, C25 highly branched isoprenoids (HBIs), and the C25 isoprenoid pentamethylicosane (PMI)