The Last Interglacial Rhine estuary - Sedimentary architecture, chronostratigraphy, preservation and analogue potential (original) (raw)
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Dating reservoir filling — a case history from the North Sea
Marine and Petroleum Geology, 1999
Secondary petroleum inclusions in reservoir sandstones in the Frùy Field and the Rind Discovery are used in combination with burial history modelling, reservoir oils and core extracts to shed light on how and when these structures received their hydrocarbon charges. Analysis of normal alkane and biomarker distributions in these three data sets:¯uid inclusions, core extracts and drill stem tests (DSTs) provide information on the changes in organic facies and maturity of petroleum in the various reservoir strata over time. The geochemistry of core extracts and DST oils in Rind and Frùy reveal that the maturity of the Rind petroleum system is higher and also of slightly less anoxic facies compared to the oil present in the Frùy system. Biodegraded oil is found today in a small sub-compartment of the Frùy Field. Using the burial history of the Frùy and the assumption that biodegradation eectively comes to a halt at 70±808C, we tentatively conclude that the ®lling of this subcompartment and the biodegradation of the oil must have occurred earlier than 30±40 m.y.b.p. and before oil from the Upper Jurassic Draupne shales more recently homogeneously ®lled the main Frùy structure. At 30±40 m.y.b.p., the Frùy structure was at a depth of 1.5±2 km, compared to the present depth of 3.5±4 km, and it is more than likely that neither the Heather nor the Draupne Formations were mature in the paleo-drainage area of the ®eld at this time. Still, the stratigraphically deeper Dunlin Formation could have been mature and the geochemical signatures of the now biodegraded oil correlates with known signatures from the Dunlin Formation in this region. In the Rind Discovery, no¯uorescent petroleum inclusions are observed in Kfeldspar overgrowths. However, the number of inclusions in quartz and plagioclase is larger than that observed in the shallower Frùy Field. From the mean homogenization temperatures of the petroleum inclusions, which are close to the present reservoir temperature, ®lling of the Frùy Field and main Rind structure is suggested to have been a recent event. A presently dry compartment penetrated by well 25/2-15R2 in the Rind Discovery contains high residual oil saturations, indicating loss of oil from this structure either by direct cap rock leakage or displacement of oil by gas and subsequent cap rock leakage. Numerous petroleum and coexisting water inclusions were found in the presently dry overpressured structure and it is clear from measurements of homogenization temperatures that the water and the petroleum inclusions are not both saturated with respect to gas. Due to the lower solubility of hydrocarbon gas in water compared to in oil, it is more likely that water inclusions are closer to saturation than are the petroleum inclusions. Using the dierence in homogenization temperatures in these two systems and the burial history, we tentatively suggest that the cap rock leakage occurred later than 10 m.y.b.p. Such information on time for reservoir ®lling and seal failure, when used to calibrate basin modelling, should facilitate better models for understanding movement of hydrocarbon¯uids in basins. #
Earth-Science Reviews, 2019
Understanding of complex sedimentary records formed by transgressive systems is critical for hydrocarbon exploration and exploitation, and carbon capture and storage. This paper discusses the facies proportions and preservation of the Last Interglacial and Holocene transgressive systems tracts in the Netherlands and their applicability as a North Sea Basin analogue for the Early Jurassic Åre Formation in the Norwegian offshore. New and existing data from both (sub-)modern transgressive Rhine records were thoroughly reviewed from a sequence stratigraphic perspective, before volumetrics were calculated and longitudinal trends quantified at reservoir scale. Large differences between the Last Interglacial and Holocene transgressive systems were found: the volume of fluvial deposits is almost six times larger and the volume of organics nearly twenty times larger in the Holocene record than in the Last Interglacial record. In contrast, the volume of estuarine deposits in the Holocene record is only half of that of the Last Interglacial record. Remarkably, both records show similar averaged sediment-trapping rates of 8–9 km 3 /ka. Initial valley configuration and relative sea-level rise-rates during both transgressions were key controls on the volume and spatial arrangement of the transgressive deposits. Relative sea-level fall and river avulsion determined what amount of sediment was left preserved after completion of one interglacial-glacial cycle. Comparison of the Late Quaternary Rhine records with the Late Triassic to Early Jurassic Åre Formation in the Heidrun Field off mid-Norway, showed the potential of the (sub-)modern Rhine records as analogues for ancient stratigraphic records. Especially the transgressive Rhine sequence from the Last Interglacial provided remarkable similarities in facies proportions, preservability, autogenic processes and controlling forcings, ranging from metre-scale vertical-successions to kilometre-scale field-wide events for parts of the Åre Formation. The side-by-side availability of the truncated Last Interglacial and (still) fully preserved Holocene transgressive system proved to be an excellent natural laboratory to study the stratigraphic architecture and assess depositional trends and preservability over longer time scales (> 100 ka). It nevertheless demonstrates that no 'one-size-fits-all' analogue exists, but that various other analogues are needed to solve the complex puzzle which the Åre Formation resembles.
Clay Minerals, 2000
The Tarbert Formation on a north±south oriented structure along the eastern flank of the Viking Graben has been studied. The reservoir in the two wells studied is buried ~100 m deeper in the northern than in the southern well. The present reservoir temperature is ~130°C. The reservoir quality is good, but due to extensive illitization of kaolin, the northern well shows lower permeability values than the southern well, for similar porosity values. The initial composition of the analysed samples in the two wells is very similar. There are no significant differences in total clay content and both wells contain K-feldspars and kaolin. However, the diagenetic alteration is more advanced in the deeper well. Total porosity is about the same in both wells but, due to illitization, the ratio of micro- vs. macro-porosity is higher in the deeper well. Petroleum emplacement in the structure occurred in two phases: oil emplacement predates, whereas gas emplacement postdates, most of the quartz c...
Proceedings 76th EAGE Conference and Exhibition 2014, 2014
Millions of barrels of hydrocarbon are produced daily from sandstone reservoir intervals in deep-water settings from petroliferous basins such as the North Sea, Niger Delta etc. These sandstones are commonly believed to have been deposited by gravity-flow processes inform of large, deep-water channel-lobe systems and low-stand fans; however, detailed investigation reveals unusual geometries that are difficult to unravel by normal depositional processes. It is believed that, the sandstones have been subject to subsurface remobilization and injection that significantly modified their geometries. Early Tertiary sandstones in the South Viking Graben, Outer Moray Firth and East Shetland Platform in the North Sea (Alba, Balder, Chestnut, Kraken, Mariner, Volund etc) show evidence of such modifications from seismic, wireline logs and core data (Lonergan et al. 2000). Products of these post-depositional processes are recognized from the Cretaceous to Pliocene intervals in the study area. They include remobilized sands, sand injectites and sand extrudites embedded in mud-rich successions. Evidences show the Cenozoic Northern North Sea underwent basin-scale remobilization and injection in a scale that has not been previous documented in the North Sea or any other basin in the world. We observe an exclusive stratigraphic overlay of these unconventional sandstones and if the sands are connected; could have impacted hydrocarbon prospectivity in the basin. Therefore, there is need to incorporate them into the current Cenozoic stratigraphic framework and geologic models at the early stages of exploration; to ascertain to what degree they may have influenced fluid flow in the basin. We propose a multiple phase emplacement through the interval.
»Late Jurassic« petroleum geology of the Dutch Central North Sea Graben
Geologische Rundschau, 1989
With 10 figures Zusammenfassung Die Sedimente des Callov bis zum Ryazan (oberer Mitteljura bis unterste Kreide, hier als ,~Oberjura~, bezeichnet) des zentralen niederliindischen Nordsee-Grabens, der den Zentralgraben und die Scruff-Gruppe nmfai~t, stellen mehrere potentielle ErdSlspeichergesteine dar. In jeder dieser beiden Gruppen sowie im Karbon und yon der Obertrias bis zur Unterkreide existieren Speichergesteine. Die strukturelle Entwicklung des Gebietes wird anhand mehrere Profile verarlschaulicht. Aui~erdem schien eine Untergliederulitg in Plattform, Zwischenplattform, ~iuf~erer sowie inlierer Graben sinnvolI. Die komplexe Entwicklungsgeschichte, die durch Kiftingphasen, Wrench-Tektoliik, Halokinese und Strukturinversion bestimmt wurde, hat die Paliiogeographie und die resultierende Sandsteinbildung intensiv beeinflut~t. Eine Aiizahl ausgew'dhlter Darstellungen der Geschichte der Sedimentiiberlagerung dienen als Beispiele fiir den Zusammenhang zwischen den strukturell bestimmten Untergruppen und dem Kohlenwasserstoffpotential des Untersuchungsgebietes.
Marine and Petroleum Geology, 2000
An extensive mineralogical and geochemical database has been compiled to evaluate the relationship between diagenesis and provenance of the Lower/Middle Jurassic sandstones from the Haltenbanken (Mid-Norway) and north Viking Graben. The data from the Haltenbanken area, from burial depths between 2.1 and 4.5 km relative to sea¯oor (RSF), show a reduction in Kfeldspar and kaolin, and a sharp increase in illite content in sandstones which are presently located at depths greater than 3.7 km RSF (120±1408C). However, there is little change in the bulk K/Al molar ratio with depth, which suggests that potassium has been conserved during the precipitation of illite and dissolution of K-feldspar. The K/Al molar ratios in most of the deeply buried Haltenbanken sandstones are greater than 1/4, which corresponds to the molar ratio in illite. This indicates that excess K-feldspar is present, which is con®rmed by petrographic observations. By contrast, deeply buried sandstones from the north Viking Graben are mostly characterised by the absence of K-feldspar, a K/Al molar ratio lower than illite and varying amounts of kaolin. This suggests that the amount of K-feldspar present at the onset of illitization (of kaolin) was lower in the north Viking Graben sandstones than in the Haltenbanken area. The degree of illitization of kaolin is higher in the Haltenbanken reservoirs as compared to the north Viking Graben, and this may be directly related to the higher K-feldspar content in the Haltenbanken sandstones. The survival of kaolin below 3.7 km RSF depth, in most of the plagioclase rich and K-feldspar poor sandstones from the north Viking Graben, therefore indicates that illitization of kaolin requires a local presence of K-feldspar in the sandstones.
Development of a mid-Holocene estuarine basin, Rhine-Meuse mouth area, offshore the Netherlands
A proper understanding of coastal development during periods of rapid sea-level rise is a prerequisite for the prediction of future coastal response to the expected acceleration in sea-level rise. However, the development of back-barrier basins, especially in river-mouth areas, during such periods is still not well understood. Here we show the response of back-barrier basins adjacent to the Rhine-Meuse river-mouth area, The Netherlands during the mid Holocene. A combination of high-resolution seismic data and cores was used to describe and explain late-Weichselian to early Holocene terrestrial and mid-Holocene back-barrier sequences. Along with dating and micropalaeontological analyses, these descriptions and explanations form the basis of a reconstruction of river-mouth and adjacent basin behaviour under conditions of rapid SLR. The nearby presence of the Rhine-Meuse estuary had a significant influence on the development of the adjacent back-barrier basin and especially its tidal channels. The back-barrier channels started to fill in between 8.3-7.4 ka BP due to decreasing rates of both sea-level rise and tidal-amplitude increase. During this time the Rhine relocated its mouth to the study area and the increased sediment delivery contributed to tidal-prism decrease and channel infill. Close to the Rhine-Meuse river mouth the back-barrier channels lay embedded in thick clayey, estuarine deposits and lateral migration of the tidal channels was limited. At greater distances, lateral migration rates increased as the thickness of cohesive back-barrier deposits decreases. The spatial pattern and stratigraphic setting of the northern channel fills suggests an episode of barrier overstepping between 7.5 and 6.6 ka BP. The mode and spatial limits of this overstepping are still not understood.