Key geological characteristics of the Saida-Tyr Platform along the eastern margin of the Levant Basin, offshore Lebanon:implications for hydrocarbon exploration

More than 60 trillion cubic feet (Tcf) of natural gas have been recently discovered in the Levant Basin (eastern Mediterranean region) offshore Cyprus, Egypt and Israel, Palestine. Un-explored areas, such as the Lebanese offshore, may yield additional discoveries. This contribution focuses the Saida-Tyr Platform (STP), an offshore geological feature adjacent to the southern Lebanese coastline – part of the eastern margin of the Levant Basin. First, an extensive synthesis of recent published research work, tackling crustal modeling, structural geology and stratigraphy will be presented. Then, a new local crustal model and the interpretation of seismic reflection specifically on the STP are discussed and emplaced in the context of the upcoming petroleum exploration activities in this region. Characteristic structural features form the limits of the STP which is believed to be an extension of the Arabian continent into the Levant Basin. Its westernmost limit consists of the extension of the crustal interface, previously termed “hinge zone”, where major plate-scale deformations are preferentially localized. The northward extension of this “hinge zone” beyond the STP can be mapped by means of major similar deformation structures (i.e. S-N-trending anticlines) and can be associated to the Levant Fracture System (LFS) – the northwestern border of the Arabian plate. The northern limit of the STP (i.e. the Saida Fault) is a typical E-W, presently active, structure that is inherited from an older, deeply rooted regional fault system, extending eastward throughout the Palmyra Basin. The STP is characterized by a variety of potential plays for hydrocarbon exploration. Jurassic and Cretaceous clastics and carbonates are believed to include reservoir plays, which could have been charged by deeper Mesozoic source rocks, and sealed by Upper Cretaceous marly layers. The edge of the Cretaceous carbonate platforms and potential carbonate buildups are well recognizable on seismic reflection profiles. The western and northern anticlinal structures bordering the STP are excellent targets for Oligo-Miocene biogenic gas charging systems. Based on integrating geodynamics, tectono-stratigraphic interpretations and petroleum systems analyses, such plays are well constrained and the exploration risk is therefore lowered

Lithofacies analysis and heterogeneity study of the subsurface Rhaetian-Pliensbachian sequence in SW Skåne and Denmark

The geological setting of Skåne is the outcome of successive phases of transtensional tectonics, block-faulting, subsidence, transpression and inversion focused around the Sorgenfrei-Tornquist Zone. The Höllviken Halfgraben is one of the major blocks in southwestern Skåne with a Rhaetian–Pliensbachian succession characterized by interbedding of arenaceous and argillaceous facies of local and regional extent. This study aims at analysing the heterogenous Rhaetian–Pliensbachian strata and is part of a major project focused on assessing the suitability of this succession for CO2 storage and/or geothermal energy production. Investigation of the lithofacies distribution has been done using Gamma Ray, Self Potential, Resistivity, Sonic, Neutron and Density data from 11 Swedish and Danish boreholes. Five boreholes have been selected for a northwest–southeast transect that is interpreted in a sequence stratigraphic approach supported with outcrop data from Kulla Gunnarstorp and Norra Albert, the Höllviken-2 core, and sidewall cores from the FFC-1 well. The study presents an eustatically controlled Rhaetian deposition and a tectonically controlled Hettangian–Pliensbachian deposition. A generally transgressive sequences dominate the Rhaetian–Pliensbachian succession. A distinctive similarity between the Rhaetian–Pliensbachian succession in southwestern Skåne and northwestern Skåne, though some differences in the relative sea level fluctuation occur during the Hettangian–Sinemurian owing to differential subsidence. Moreover, the Rhaetian–Pliensbachian succession in the Höllviken Halfgraben shows a dominance of fine-grained facies, and thus rendered less favorable conditions for geothermal water production. However, the succession is proved convenient for CO2 storage having adequate porosities (>20%), enough permeability (>100 mD), occurring at a depth of more than 800 m and sealed by tight claystone layers.Skåne har formats genom flera tektoniska och geologiska processer kopplade till en stor sprick- och rörelsezon – Sorgenfrei-Tornquistzonen. I sydvästra Skåne finns ett större förkastat block, Höllvikensänkan, med sedimentära lager från trias-juratiden. Denna lagerföljd karakteriseras av sandsten varvat med lersten som avsatts både lokalt och över större områden. Studien har fokuserat på analys av lagerföljden och är en del i ett större projekt för att utvärdera om bergrunden är lämplig för lagring av CO2 och/eller användas till geotermisk energiutvinning. Geofysisk data från elva svenska och danska borrhål, samt från fältdata, har använts för att göra en sådan utvärdering. Utifrån dessa data har en NV-SÖ sektion skapats och den har påvisat att det dåvarande havet i sydvästra Skåne var influerat av globala havsnivåförändringar i slutet av trias men att havsnivån i början av jura styrdes av lokala till regionala tektoniska rörelser. Bergrunden i det studerade tidsintervallet domineras av finkornigt material vilket gör att det är mindre gynnsamt för geotermisk energiproduktion. Däremot uppfyller bergrunden, på ett djup större än 800 m, kriterierna för att lagra CO2

Geochemical and petrographic characterization of Campanian–Lower Maastrichtian calcareous petroleum source rocks of Hasbayya, South Lebanon

International audienceSantonian–Paleocene marls and fine grained carbonates have been sampled in Hasbayya locality, south Lebanon, in order to evaluate their organic matter (OM) content, petroleum source rock potential, and assess their depositional environment. Methods included total organic carbon (TOC), total inorganic carbon (TIC), total sulphur (TS), Rock-Eval pyrolysis, organic and inorganic petrography, X-ray fluorescence (XRF), gas chromatography–mass spectrometry (GC–MS) and Curie-point-pyrolysis-gas chromatography–mass spectrometry (CP-Py-GC–MS). TOC, Rock-Eval, and vitrinite reflectance (VRr) results reveal excellent immature petroleum source rocks within the Campanian–lower Maastrichtian interval with TOC up to 11.6 wt%, hydrogen index (HI) up to 872 mg/gTOC, Tmax up to 433 °C and VRr average of 0.36%. Biomarker ratios and maceral analysis suggest a marine depositional environment with a dominance of algal as well as submicroscopic OM. Original sediment composition and redox sensitive geochemical parameters suggest deposition of the OM rich intervals under an oxygen minimum zone (OMZ) that was emplaced and controlled by primary productivity and nutrient supply. Pyrolysate composition shows an important content of organic sulphur compounds (thiophenes) increasing with TOC and thus indicating the presence of Type II and Type IIS kerogen in the analysed sample set, which is consistent with the presence of immature solid bitumen in the Hasbayya region.The data produced in this study, coupled with regional correlations, allow us to construct a conceptual depositional model for the Upper Cretaceous OM rich rocks of the eastern Mediterranean suggesting deposition under a productivity belt localized along the inner and outer shelf leading to a decrease in source rock quality and a shift in kerogen type toward the deeper parts of the Levant Basin

Key geological characteristics of the Saida-Tyr Platform along the eastern margin of the Levant Basin, offshore Lebanon: implications for hydrocarbon exploration

More than 60 trillion cubic feet (Tcf) of natural gas have been recently discovered in the Levant Basin (eastern Mediterranean region) offshore Cyprus, Egypt and Israel, Palestine. Un-explored areas, such as the Lebanese offshore, may yield additional discoveries. This contribution focuses the Saida-Tyr Platform (STP), an offshore geological feature adjacent to the southern Lebanese coastline – part of the eastern margin of the Levant Basin. First, an extensive synthesis of recent published research work, tackling crustal modeling, structural geology and stratigraphy will be presented. Then, a new local crustal model and the interpretation of seismic reflection specifically on the STP are discussed and emplaced in the context of the upcoming petroleum exploration activities in this region. Characteristic structural features form the limits of the STP which is believed to be an extension of the Arabian continent into the Levant Basin. Its westernmost limit consists of the extension of the crustal interface, previously termed “hinge zone”, where major plate-scale deformations are preferentially localized. The northward extension of this “hinge zone” beyond the STP can be mapped by means of major similar deformation structures (i.e. S-N-trending anticlines) and can be associated to the Levant Fracture System (LFS) – the northwestern border of the Arabian plate. The northern limit of the STP (i.e. the Saida Fault) is a typical E-W, presently active, structure that is inherited from an older, deeply rooted regional fault system, extending eastward throughout the Palmyra Basin. The STP is characterized by a variety of potential plays for hydrocarbon exploration. Jurassic and Cretaceous clastics and carbonates are believed to include reservoir plays, which could have been charged by deeper Mesozoic source rocks, and sealed by Upper Cretaceous marly layers. The edge of the Cretaceous carbonate platforms and potential carbonate buildups are well recognizable on seismic reflection profiles. The western and northern anticlinal structures bordering the STP are excellent targets for Oligo-Miocene biogenic gas charging systems. Based on integrating geodynamics, tectono-stratigraphic interpretations and petroleum systems analyses, such plays are well constrained and the exploration risk is therefore lowered

Origins of hydrocarbons in the Geneva Basin: insights from oil, gas and source rock organic geochemistry

International audienceAn extensive subsurface investigation evaluating the geothermal energy resources and underground thermal energy storage potential is being carried out in the southwestern part of the Swiss Molasse Basin around the Geneva Canton. Among this process, the evaluation of the petroleum source-rock type and potential is an important step to understand the petroleum system responsible of some oil and gas shows at surface and subsurface. This study provides a first appraisal of the risk to encounter possible undesired occurrence of hydrocarbons in the subsurface of the Geneva Basin. Upon the numerous source-rocks mentioned in the petroleum systems of the North Alpine Foreland Basin, the marine Type II Toarcian shales (Lias) and the terrigenous Type III Carboniferous coals and shales have been sampled from wells and characterized with Rock–Eval pyrolysis and GC–MS analysis. The Toarcian shales (known as the Posidonia shales) are showing a dominant Type II organic matter composition with a Type III component in the Jura region and the south of the basin. Its thermal maturity (~ 0.7 VRr%) shows that this source-rock currently generates hydrocarbons at depth. The Carboniferous coals and shales show a dominant Type III organic matter with slight marine to lacustrine component, in the wet gas window below the Geneva Basin. Two bitumen samples retrieved at surface (Roulave stream) and in a shallow borehole (Satigny) are heavily biodegraded. Relative abundance of regular steranes of the Roulave bitumen indicates an origin from a marine Type II organic matter. The source of the Satigny bitumen is supposedly the same even though a deeper source-rock, such as the lacustrine Permian shales expelling oil in the Jura region, can’t be discarded. The oil-prone Toarcian shales in the oil window are the most likely source of this bitumen. A gas pocket encountered in the shallow well of Satigny (Geneva Canton), was investigated for molecular and stable isotopic gas composition. The analyses indicated that the gas is made of a mixture of microbial (very low δ13C1) and thermogenic gas. The isotopic composition of ethane and propane suggests a thermogenic origin from an overmature Type II source-rock (> 1.6 VRr%) or from a terrigenous Type III source at a maturity of ~ 1.2 VRr%. The Carboniferous seems to be the only source-rock satisfying these constraints at depth. The petroleum potential of the marine Toarcian shales below the Geneva Basin remains nevertheless limited given the limited thickness of the source-rock across the area and does not pose a high risk for geothermal exploration. A higher risk is assigned to Permian and Carboniferous source-rocks at depth where they reached gas window maturity and generated large amount of gas below sealing Triassic evaporites. The large amount of faults and fractures cross-cutting the entire stratigraphic succession in the basin certainly serve as preferential migration pathways for gas, explaining its presence in shallow stratigraphic levels such as at Satigny

Integrated 3D forward stratigraphic and petroleum system modeling of the Levant Basin, Eastern Mediterranean

International audienceThe Eastern Mediterranean Levant Basin is a proven hydrocarbon province with recent major gas discoveries. To date, no exploration wells targeted its northern part, in particular the Lebanese offshore. The present study assesses the tectono‐stratigraphic evolution and related petroleum systems of the northern Levant Basin via an integrated approach that combines stratigraphic forward modeling and petroleum systems/basin modeling based on the previous published work. Stratigraphic modeling results provide a best‐fit realisation of the basin‐scale sedimentary filling, from the post‐rift Upper Jurassic until the Pliocene. Simulation results suggest dominant eastern marginal and Arabian Plate sources for Cenozoic siliciclastic sediments and a significant contribution from the southern Nilotic source mostly from Lower Oligocene to Lower Miocene. Basin modeling results suggest the presence of a working thermogenic petroleum system with mature source rocks localised in the deeper offshore. The generated hydrocarbons migrated through the deep basin within Jurassic and Cretaceous permeable layers towards the Latakia Ridge in the north and the Levant margin and offshore topographic highs. Furthermore, the basin model indicates a possibly significant influence of salt deposition during Messinian salinity crisis on formation fluids. Ultimately, the proposed integrated workflow provides a powerful tool for the assessment of petroleum systems in underexplored areas