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Diatoms in oil and gas exploration
Abstract
Introduction Diatoms constitute an important rock-forming microfossil group. They evolved rapidly during the Cenozoic, and unlike other microfossils, diatoms are found in marine, brackish, and lacustrine sediments, and are thus useful for age dating and correlating sediments that accumulated in a variety of environments. Their fossil assemblages are reflective of the environments in which they lived, and their recovery in wells and outcrops can provide information on paleochemistry and paleobathymetry. They are most useful to the oil and gas industry in age dating and correlating rocks that lack or have poor recovery of calcareous microfossils, such as “cold-water” Tertiary marine rocks, and sediments that accumulated in lacustrine basins and in brackish-water settings. Age dating and correlation of sedimentary rocks are important for hydrocarbon exploration in order to understand the geologic history of a basin as it relates to formation of source rocks, reservoirs, structures, and seals. The timing of expulsion of oil and gas is a critical factor in determining the prospect potential of a basin for hydrocarbon, and necessitates an understanding of the geochronology of events. The ability to correlate subsurface rocks is a prerequisite to mapping the distribution of reservoir facies and the interpretation of sequence stratigraphy. Environmental data pertaining to paleobathymetry and paleochemistry provide important information on the geologic history of a basin and predictability of reservoir distribution. For example, shales that are barren of calcareous microfossils may have accumulated in deep water, beneath the carbonate compensation depth, or in brackish or freshwater.
... Many workers have attributed diatoms as major contributors to crude oil deposits (Ehrenberg, 1839 ;Whitney, 1865Whitney, , 1867Anderson, 1926 ;Tolman, 1927 ;Hanna, 1928 ;Levorsen and Berry, 1967 ;Hunt, 1979Hunt, , 1996North, 1985 ;Mertz, 1989 ;Aoyagi and Omokawa, 1992 ;Holba et al., 1998a, b ;Gelin et al., 1999 ;Breger, 2001 ;Johnson and Grimm, 2001 ;Gurgey, 2003 ;Krebs, 1999 ;Krebs et al., 2011 ) , but the overall total contribution of diatoms to worldwide petroleum reserves has not been estimated (Ramachandra et al., 2009 ) . Keeping in mind that approximately half of the crude oil deposits have been utilized (Guliyev et al., 2001 ;Fortman et al., 2008 ) , we need to work out an overall guesstimate of total worldwide petroleum deposits continuing natural contributed by diatoms. ...
... Diatom biostratigraphy is used to identify the potential source rocks for petroleum deposits (Krebs, 1999 ;Krebs et al., 2011 ) , but sometimes it is not feasible as silica cell walls of diatoms are prone to dissolution (Koning et al., 1997 ;Lončarić et al., 2007 ) . Preservation of diatom frustules in sediments depends on rapid burial, lack of prolonged exposure to alkaline (pH > 7) pore waters, and absence of post-burial temperatures in excess of 35 °C (Calvert, 1974 ) . ...
Crude oil or petroleum is derived from natural sources which are in the form of organic matter deposited along with the sediments in sedimentary basins from geological past (Hunt, 1863; Hunt et al., 2002; Kvenvolden, 2008). Living organisms of various kinds contribute to production of hydrocarbons as a normal part of their existence in which algae are thought to be one of the principal contributors to production of petroleum (Whitmore, 1944; Oakwood, 1946). They are also considered to yield a large percentage of organic compounds more closely analogous to petroleum as identified through chemical structure of kerogen; therefore, abiogenic origin of petroleum has not been accepted by modern geologists. Brongersma-Sanders (1951) emphasized the impressive local development of abundant plankton in areas of upwelled nutrient-rich ocean waters. It seems that both geologically and geochemically aquatic plant and animal life offer the most likely source material for the bulk of our hydrocarbon reserves.
... Since diatoms are photosynthetic, they synthesize food in the form of carotenoids, specially fucoxanthin and lipids. They are important crude oil reservoirs, and geologists believe that 30% of the world's crude oil comes from diatoms (Krebs et al. 2010). On the other set, agriculturalists believe that diatoms make ten times more oil per hectare than the oil seeds (Hu et al. 2008), with theoretically calculated values reaching 200 times (Sheehan et al. 1998;Hu et al. 2008). ...
The sudden outbreak of Covid-19 has shut down the planet and human activities along with a huge loss of lives. There is, thus, a serious concern in monitoring routinely new microscopic species and their influence on our environment at different trophic levels. Our oceans are reservoirs of a wide variety of both plant and animal life. About 50% of it is constituted by phytoplanktons, of which diatoms constitute a dominant part in productive waters. Besides being the reservoir of food stored in the form of oil, diatoms are rich in antioxidants like carotenoids (fucoxanthins) and sulfated polysaccharides, which have antiviral properties. They are often found in assemblages with other planktons, including bacteria, fungi, and viruses, of which bacteria are the most common. Such pathogenic planktons in their phycosphere community may bring sudden mortality, resulting in changes in carbon biomass and community. It may trigger either eruption of diatom blooms, new species, phenotypic plasticity, or extinction of existing ones. This review discusses the fate of diatom assemblages and their morphological plasticity dependent on their phycosphere influenced by environmental and anthropogenic factors and why regular monitoring of diatom assemblages and metabolites they produce is necessary for the healthy environment around us in a post-Covid environment.
... Diatoms besides biofilming the ML that enhances the sinking of pollutants in the water bodies fix almost 25% of global CO 2 32 . They meet 30% of world's needs for crude oil, due to lipid rich bodies in their cells 33 . Furthermore, diatoms are nature's freely available silica which has wide applications in forensics, and material science [34][35][36] . ...
Abstract In the present study, embellishment or beautification of diatoms on substrates like plastics, polydimethylsiloxane, graphite, glass plate, and titanium dioxide, triggered by exopolysaccharides was examined under laboratory conditions. Exopolysaccharides are secreted mainly by primary colonisers, bacteria, which is succeeded by secondary colonisers i.e. diatoms. Both diatom (Nitzschia sp.4) and bacteria (Bacillus subtilis) were exposed with substrates separately for 30 days. Diatoms adhere on substrates strongly, not only because of surface roughness of different substrates but also the nanoporous architecture of diatoms which enhanced their embellishment. This study attempted to identify the substrates that adhere to diatoms strongly and was mainly analyzed by scanning electron microscope and further the observations are well supported by math work software (MATLAB). The variation of diatom’s binding on different substrates is due to the influence of marine litters on diatom population in ocean beds where they undergo slow degradation releasing macro, micro and nanoparticles besides radicals and ions causing cell death. Therefore a proof-of-concept model is developed to successfully deliver a message concerning benefit of using different diatom species.
... In gas and oil exploration, diatom analysis sometimes becomes a critical procedure for age dating and correlating rocks especially if those rocks are of poor preservation for calcareous microfossils or lacustrine sediments. Diatoms may be more than help- ful in understating the paleoenvironmental events of the basin with higher resolution biostratigraphy, an important task in evaluating basin hydrocarbons potential and to study the reservoir distribution (Krebs, Gladenkov, & Jones 2010). ...
... This material can be processed by relatively simple means to remove organic or calcareous matter and then used in many industries, e.g., as fine abrasives and filtration material (Smol and Stoermer 2010). Fossil diatoms are also important as stratigraphical markers, e.g., for oil exploration (Krebs et al. 2010). ...
The diatoms (Bacillariophyta) are the most species-rich group of autotrophic algae, found in fresh, brackish, and marine waters worldwide, and also in damp terrestrial habitats. They are well represented in marine phytoplankton and may account for 20% of global photosynthetic carbon fixation. However, the vast majority of the estimated 100,000 species are benthic, living attached to surfaces or gliding over sediments using a unique organelle, the raphe system. Flagellate cells are absent, except in the sperm of some lineages. Diatoms possess a similar photosynthetic apparatus to that present in several other stramenopile lineages (with fucoxanthin and chlorophyll c as the principal accessory pigments) but are easily recognized by the unique construction and composition of their cell wall, which is usually strongly silicified and consists of two overlapping halves (thecae); these in turn consist of a larger end piece (valve) and a series of narrow strips (girdle bands). Expansion of the cell occurs by sliding apart of the thecae and addition of new bands to the inner, overlapped theca. At cell division, each daughter cell inherits one of the thecae of the parent and forms a new theca internally. Hence, because the silicified wall is inelastic, average cell size usually declines during vegetative growth and has to be restored through expansion of a special cell, the auxospore, usually after sexual reproduction. A few diatoms have lost their plastids and are osmotrophic. Classification has traditionally relied on details of valve structure. There is a rich fossil record.
... This material can be processed by relatively simple means to remove organic or calcareous matter and then used in many industries, e.g., as fine abrasives and filtration material (Smol and Stoermer 2010). Fossil diatoms are also important as stratigraphical markers, e.g., for oil exploration (Krebs et al. 2010). ...
The diatoms (Bacillariophyta) are the most species-rich group of autotrophic algae, found in fresh, brackish, and marine waters worldwide, and also in damp terrestrial habitats. They are well represented in marine phytoplankton and may account for 20% of global photosynthetic carbon fixation. However, the vast majority of the estimated 100,000 species are benthic, living attached to surfaces or gliding over sediments using a unique organelle, the raphe system. Flagellate cells are absent, except in the sperm of some lineages. Diatoms possess a similar photosynthetic apparatus to that present in several other stramenopile lineages (with fucoxanthin and chlorophyll c as the principal accessory pigments) but are easily recognized by the unique construction and composition of their cell wall, which is usually strongly silicified and consists of two overlapping halves (thecae); these in turn consist of a larger end piece (valve) and a series of narrow strips (girdle bands). Expansion of the cell occurs by sliding apart of the thecae and addition of new bands to the inner, overlapped theca. At cell division, each daughter cell inherits one of the thecae of the parent and forms a new theca internally. Hence, because the silicified wall is inelastic, average cell size usually declines during vegetative growth and has to be restored through expansion of a special cell, the auxospore, usually after sexual reproduction. A few diatoms have lost their plastids and are osmotrophic. Classification has traditionally relied on details of valve structure. There is a rich fossil record.
Diatoms, a unique group of algae colonising a wide range of aquatic habitats and contributing to human well-being in many ways. We list and summarise these services using the classification of the Millennium Ecosystem Assessment (MEA), i.e. supporting, regulating, provisioning and cultural services. The most relevant supporting services are photosynthesis and primary production, as well as sediment formation. They also play a key role in nutrient cycling and habitat provisioning and serve as food for many organisms. Regulating services as oxygen production, climate control or sediment stabilisation are difficult to discuss without diatoms. Many provisioning services, directly used by humans, can be obtained from diatoms. These are tangible products such as medicines and immunostimulants but direct technologies such as wastewater treatment, micro- and nanotechnologies were also developed using diatoms. Studying of the past, present, and future linked to diatoms as a tool for palaeolimnology, ecological status assessment of waters and climate modelling is essential. Finally, the impressive morphology and ornaments of diatom frustules make them one of the most spectacular microorganisms, inspiring artists or providing a number of educational opportunities. Therefore, protecting aquatic habitats they inhabit is not simply a nature conservation issue but the key for human well-being in the future.
The often widespread occurrence of diatoms in the marine sediments of the North Sea Palaeogene has long been recognised. They occur in abundance through a number of intervals where calcareous microfossils are absent (due to palaeoenvironmental conditions and subsequent dissolution). However, poor preservation has previously impeded the taxonomic identification of these diatom assemblages, with most specimens occurring as pyritised inner moulds (steinkerns). This study has involved the first detailed description of these assemblages, which was achieved through the use of electron microscopy combined with comparisons with well-preserved specimens, and a survey of original species descriptions held in the Natural History Museum. These techniques have enabled the identification of a total of 79 species, 40 of which have not previously been formally described in pyritised form. Material analysed in this study (including samples from exploration wells and coeval onshore sections around the North Sea Basin) has led to the recognition of a number of diatom events which broadly form three major assemblages through the North Sea Palaeocene sequence. The lowermost is the most diverse, occurring within the volcaniclastic Sele and Balder formations and their onshore equivalents around the Paleocene/Eocene boundary interval. The relationship of abundant diatomaceous deposits to vulcanicity during this interval is discussed, together with other factors (including increased nutrient levels) encouraging the proliferation of diatoms. A later, less diverse assemblage in the mid Eocene includes more cosmopolitan species; above this is a distinctive Oligocene to mid Miocene assemblage. The state of preservation of diatom assemblages varies markedly around the North Sea Basin; this has been discussed and microprobe analyses conducted. A number of taxonomic revisions of previously published species (both pyritised and non-pyritised) have also been carried out, including translations of descriptions into English (and their emendment where necessary). A new genus, Cylindrospira (consisting of two species, C. simsi and C. homanni) is described which has no living representatives, but has features found in both extinct and extant genera. It is palaeoenvironmentally significant, occurring in a brackish facies of the Fur Formation diatomite, age-equivalent to one of the main diatomaceous intervals in the North Sea. Prior to this study, only fully marine diatoms had been documented from the Paleocene. Existing microfossil zonation schemes for the North Sea Palaeogene have been refined, by integrating diatom events with those of stratigraphically well-defined fossil groups such as foraminifera and silicoflagellates. This has ebabled their correlation with other sections, and an improved understanding of palaeocirculation changes through the North Sea Palaeogene.
In the Western US, 12 obligate freshwater species of Actinocyclus Ehrenberg are restricted to the early and middle Miocene. Maximum diversity (11 species) was attained during the early middle Miocene, before the appearance of obligate lacustrine genera of the gamily Thalassiosiraceae. Fossil lacustrine Actinocyclus spp. are found elwhere in the world and may have geologic ranges that differ in detail, but which are generally similar to those in the Western US. -from Authors
Organic-rich hemipelagic shales of the lower Monterey Formation in the Salinas basin of central California record intervals of enhanced productivity and accumulation of fine-grained biogenic and clastic sediment under dysaerobic to anoxic conditions during the late early Miocene and early middle Miocene. These deposits are good potential oil source rocks, and consist primarily of (1) pelagic components (biogenic carbonate and silica, and marine organic matter), (2) fine-grained siliciclastic material transported mainly by sediment gravity processes, and (3) an associated assemblage of diagenetic phases. A paragenetic sequence is described. Although conventional geochemical maturity measures suggest that these source rocks have not entered the main oil window, relatively early hydrocarbon generation is well documented from Monterey shales, and these rocks are likely a significant source of much Salinas basin oil.
Relatively well-preserved diatoms, often cemented together as silica aggregates and mainly composed of opal-A, are present in Upper Oligocene sediments at burial depths down to about 1500 m in the northern North Sea. The taxon Paralia thybergii dominates, but Stephanopyxis spp., Coscinodiscus spp. and sponge spicules are also commonly present. The diatom flora indicates a nearshore environment and a shallow marine northern North Sea basin at that time. The silica facies interfinger with glauconitic facies to the west, as seen in well 34/7-1, and this also suggests shallow marine conditions and sediment starvation. A structural high located between 60 and 61°N restricts the extensive biogenic silica deposits to the northern part of the North Sea. Seismic mapping shows that a basin with water depths up to at least 800 m existed in the northernmost North Sea-Møre Basin area in mid-Oligocene time. The basin was bounded by shallow shelf areas in the east and southwest. The Late Oligocene basin configuration caused upwelling when the wind came from a southerly direction. Preservation of the siliceous sediments indicates highly productive surface waters, in a shallow basin with starved clastic sedimentation in the northern North Sea with wind-driven upwelling in a north-south direction.
Traces of basic explosive volcanic activity are widespread in the lower Tertiary of North Sea wells, stretching 1000 km north to south and 300 km west to east. Volcanic ashes and minute glass debris are included in the sedimentary section, often associated with diatoms; their preservation varies with the conditions of deposition. Several phases can be distinguished. The acme of the major one occurs during the most regressive period of the Lower Tertiary, immediately preceding the uppermost Palaeocene-Lower Eocene transgression. It forms an excellent time marker, associated with a seismic horizon plotted over most of the North Sea. The Danish and north German outcrops seem contemporaneous with this phase. An earlier episode probably in lowermost Thanetian, is now known in the Halibut Horst and Forties areas and in a few wells of the Viking Graben.
Graphic correlation, based on a Cartesian coordinate system, is a tool which is used to derive precise, consistent, and highly resolved biostratigraphic correlations among wells and/or measured outcrop sections thereby reducing technical risk in hydrocarbon exploration. Non-paleontological data may also be correlated using this method. A database of fossil ranges, the composite standard, is created by graphic correlation. Graphic correlation and composite standard construction are readily handled by computer software. Large quantities of biostratigraphic data can be compiled, organized, retrieved, and applied to future correlation studies. The enhanced resolution of this method facilitates recognition of unconformities and condensed sections, resulting in interpretations well suited for sequence stratigraphic basin studies. Used in conjunction with log and seismic data, this technique improves the explorationist’s ability to identify and exploit subtle stratigraphic traps. It can also facilitate recognition of ancestral structural features masked by unconformities and overlying flat lying beds.
The technique is a mainstay in Amoco’s approach to biostratigraphy. It is a powerful tool for evaluating and interpreting paleontological data generated in-house as well as that acquired from vendors, through data trades, in acreage bid round data packages purchased from foreign governments, and from the literature. This method does not replace traditional paleontological techniques; it is a tool for data handling and display designed to enhance traditional methods.
Paleogene and Neogene stratigraphic schemes of Sakhalin are characterized. The schemes comprise from 11 to 12 regional stages and up to 50 formations. A calendar of various geological events (tectonic, volcanic, sedimentation, climatic, biotic, and others) is compiled on that basis. In particular, stages of different scale changes in marine biotic assemblages are revealed and discriminated into major (15-17 Ma long) or subordinate and minor (2.0 and 0.3-1 Ma long). Several phases of the tectonic and volcanic activation, as well as periods of warming and cooling are distinguished. The analysis of geological events shows that many of them are synchronous to a certain extent, though it does not always happen that their causes and effects are understandable.
This article presents the Oligocene and lower Miocene diatom zonation for the North Pacific. The data obtained in Leg 145 of the Oceanic Drilling Program (ODP) allowed a subdivision of Oligocene and lower Miocene deposits of the subarctic Pacific into seven zones. In addition, the correlation between diatom assemblages from the Komandorskie and Japanese Islands and the high southern latitudes enabled the first recognition of a lower Oligocene zone in the North Pacific (the Rhizosolenia oligocaenica Zone with the lower and upper boundaries at the levels of 33.7 and 30.2 Ma, respectively). Diatom assemblages from more than 20 sections of middle-high latitudes of the Pacific region (Kamchatka, Sakhalin, Japan, and other areas) are correlated with the suggested zonation. Copyright © 1998 by MAEe cyrillic signK Hayκa/Interperiodica Publishing.