New insights into the organic geochemistry of the Otway Basin

2020 ◽  
Vol 60 (2) ◽  
pp. 712
Author(s):  
Tony Hill ◽  
Betina Bendall ◽  
Andrew Murray
Keyword(s):  
Organic Geochemistry ◽  
South Australia ◽  
Hydrocarbon Production ◽  
Recent Success ◽  
Algal Organic Matter ◽  
Geochemical Analyses ◽  
Rock Eval ◽  
Lacustrine Facies ◽  
Low Sulfur ◽  
Paraffinic Oil

The Penola Trough of the Otway Basin in South Australia has enjoyed over 20 years of commercial hydrocarbon production from the sandstones of the Early Cretaceous Otway Group with 71.46 PJ sales gas and 65840 kL of condensate produced from five fields until production ceased in 2011. Recent success in Haselgrove 3, where a newly discovered deeper reservoir underlying depleted reservoirs of the Pretty Hill Formation flowed 25 MMscfd on test heralds a new phase of exploration and appraisal with a 2C Contingent Resource of 87 PJ assigned to the discovery. These hydrocarbons are considered to have been principally derived from lacustrine, floodplain and back swamp facies of the Pretty Hill Formation and lacustrine facies of the underlying Casterton Formation. The South Australia Department for Energy and Mining is currently investigating an unnamed Late Jurassic syn-rift sequence of interbedded metasediments, tuffaceous sediments and organically-rich shale, first identified as fractured basement in Sawpit 1, located on the northern flanks of the Penola Trough and which unconformably underlies the Casterton Formation. A low-sulfur medium-gravity paraffinic oil was recovered from drill stem tests from this well and subsequent total organic carbon and Rock-Eval analyses for the same unit in nearby Sawpit 2 identified a source rock containing algal organic matter and thought to be deposited in a deep anoxic lake setting. In this paper, we will present the preliminary results of detailed geochemical analyses of rocks and rock extracts from this previously unrecognised syn-rift sequence and discuss implications for hydrocarbon prospectivity in the deeper portions of the Penola Trough.

scholarly journals Age and paleoenvironment of the Nukhul Formation, Gulf of Suez, Egypt: Insights from palynology, palynofacies and organic geochemistry

GeoArabia ◽  
2013 ◽  
Vol 18 (4) ◽  
pp. 137-174
Author(s):  
Haytham El Atfy ◽  
Rainer Brocke ◽  
Dieter Uhl
Keyword(s):  
Nile Delta ◽  
Organic Geochemistry ◽  
Regional Scale ◽  
Tectonic Activity ◽  
Gulf Of Suez ◽  
Spores And Pollen ◽  
Shallow Marine ◽  
History Of ◽  
Geochemical Analyses ◽  
Rock Eval

ABSTRACT Palynological results of a detailed study carried out on 56 samples retrieved from two selected wells (GH 404-2A and SA-E6A) of the Hilal and Shoab Ali fields within the southern part of the Gulf of Suez, Egypt, are presented. This study is mainly focused on the poorly dated Nukhul Formation, for which very little information from palynology is available despite its importance from a petroleum viewpoint. The assemblages discovered in our study are moderately preserved and reveal a sparse but significant record of spores and pollen and dinoflagellates together with highly diverse fungi and algal taxa, e.g. Botryococcus and Pediastrum. A latest Oligocene–Early Miocene (Chattian–Aquitanian) age has been suggested for the Nukhul Formation, based on compiling palynostratigraphic and ecologic data obtained from palynomorphs that have previously been assumed to be representatives for this period on a regional scale. In addition, the Oligocene/Miocene Boundary (OMB) could be lithostratigraphically defined within the studied formation, most likely at the boundary between the lower Shoab Ali Member and upper Ghara Member. A fungal/algal ‘event’ within the interval from 11,370–11,430 ft in the GH 404-2A Well may be associated with a strong regressive phase. Such a regression was previously observed in the Nile Delta and other locations around the Red Sea province, and may be assigned to the global Mi-1 glaciation event at the OMB. However, not only glacial-driven eustacy but also tectonic activity related to the Gulf of Suez rifting may have contributed in forming such an event. Palynofacies investigations were carried out under both transmitted and fluorescence microscopy and the results were partly supplemented by existing organic geochemical analyses (GH 404-2A Well) involving Rock-Eval pyrolysis and total organic carbon (TOC) measurements. The analysis was used to interpret the depositional regime, paleoenvironment and thermal maturation history of the studied succession. These results support the temporary existence of shallow, pond- or lake-like aquatic habitats during deposition of the lower Shoab Ali Member that evolved into a shallow-marine environment with the onset of the deposition of upper Ghara Member of the Nukhul Formation.

New insights into the stratigraphy of the Otway Basin

2020 ◽  
Vol 60 (2) ◽  
pp. 691
Author(s):  
Betina Bendall ◽  
Anne Forbes ◽  
Dan Revie ◽  
Rami Eid ◽  
Shannon Herley ◽  
...  
Keyword(s):  
South Australia ◽  
Petroleum Exploration ◽  
Hydrocarbon Production ◽  
Sedimentary Sequences ◽  
Structural Relationships ◽  
Geochemical Variation ◽  
Complex Structural ◽  
Geochemical Analyses ◽  
Stratigraphic Nomenclature ◽  
The Antarctic

The Otway Basin is one of the best known and most actively explored of a series of Mesozoic basins formed along the southern coastline of Australia by the rifting of the Antarctic and Australian plates during the Cretaceous. The basin offers a diversity of play types, with at least three major sedimentary sequences forming conventional targets for petroleum exploration in the onshore basin. The Penola Trough in South Australia has enjoyed over 20 years of commercial hydrocarbon production from the sandstones of the Early Cretaceous Otway Group comprising the Crayfish Subgroup (Pretty Hill Formation and Katnook sandstones) and Eumeralla Formation (Windermere Sandstone Member). Lithostratigraphic characterisation and nomenclature for these sequences are poorly constrained, challenging correlation across the border into the potentially petroleum prospective Victorian Penola Trough region. The Geological Survey of Victoria (GSV), as part of the Victorian Gas Program, commissioned Chemostrat Australia to undertake an 11-well chemostratigraphic study of the Victorian Otway Basin. The South Australia Department for Energy and Mining, GSV and Chemostrat Australia are working collaboratively to develop a consistent, basin-wide schema for the stratigraphic nomenclature of the Otway Basin within a chemostratigraphic framework. Variability in the mineralogy and hence inorganic geochemistry of sediments reflects changes in provenance, lithic composition, facies changes, weathering and diagenesis. This geochemical variation enables the differentiation of apparently uniform sedimentary successions into unique sequences and packages, aiding in the resolution of complex structural relationships and facies changes. In this paper, we present the preliminary results of detailed geochemical analyses and interpretation of 15 wells from across the Otway Basin and the potential impacts on hydrocarbon prospectivity.

scholarly journals Geochemical Considerations from the Carboniferous Unconventional Petroleum System of SW Iberia

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 811
Author(s):  
Gabriel A. Barberes ◽  
Rui Pena dos Reis ◽  
Nuno L. Pimentel ◽  
André L. D. Spigolon ◽  
Paulo E. Fonseca ◽  
...  
Keyword(s):  
Random Distribution ◽  
Thermal Evolution ◽  
Organic Geochemistry ◽  
Black Shales ◽  
Petroleum System ◽  
Point Of View ◽  
Gas Reservoir ◽  
Thermal Maturation ◽  
Petrographic Analyses ◽  
Rock Eval

The Baixo Alentejo Flysch Group (BAFG) is an important stratigraphic unit that covers over half of the South Portuguese Zone (SPZ) depositional area, and it is composed by three main tectono-stratigraphic units: the Mértola, Mira, and Brejeira formations. All of these formations contain significant thicknesses of black shales and have several wide areas with 0.81 wt.%, 0.91 wt.%, and 0.72 wt.% average total organic carbon (TOC) (respectively) and thermal maturation values within gas zones (overmature). This paper is considering new data from classical methods of organic geochemistry characterization, such as TOC, Rock–Eval pyrolysis, and organic petrography, to evaluate the unconventional petroleum system from the SPZ. A total of 53 samples were collected. From the stratigraphical point of view, TOC values seem to have a random distribution. The Rock–Eval parameters point out high thermal maturation compatible with gas window (overmature zone). The samples are dominated by gas-prone extremely hydrogen-depleted type III/IV kerogen, which no longer has the potential to generate and expel hydrocarbons. The petrographic analyses positioned the thermal evolution of these samples into the end of catagenesis to metagenesis (wet to dry gas zone), with values predominantly higher than 2 %Ro (dry gas zone). The presence of thermogenic hydrocarbon fluids characterized by previous papers indicate that the BAFG from SPZ represents a senile unconventional petroleum system, working nowadays basically as a gas reservoir.

Origin of the secondary REE-minerals at the Paratoo copper deposit near Yunta, South Australia

2006 ◽  
Vol 70 (6) ◽  
pp. 609-627 ◽  
Author(s):  
J. Brugger ◽  
J. Ogierman ◽  
A. Pring ◽  
H. Waldron ◽  
U. Kolitsch
Keyword(s):  
Base Metal ◽  
South Australia ◽  
Copper Deposit ◽  
Rock Interaction ◽  
Widespread Occurrence ◽  
Fe Oxide ◽  
Left Behind ◽  
Copper Gold ◽  
Geochemical Analyses ◽  
Light Rare Earth Elements

AbstractThe Paratoo copper deposit, located in the Neoproterozoic to Cambrian Adelaide Geosyncline, South Australia, produced around 360 tons of Cu between 1888 and 1967 from oxidized ores. The deposit is located in the core of a breached, doubly plunging anticline, near a zone of disruption containing brecciated Adelaidean sedimentary rocks and dolerite (‘Paratoo Diapir’), and hosted in dolomitic shales of the Neoproterozoic Burra Formation. Near the surface, the mineralization resides mainly in deeply weathered quartz-magnetite-sulphide (pyrite, chalcopyrite) veins (⩽10 cm wide). At depth, drill cores reveal disseminated magnetite, pyrite, chalcopyrite, copper sulphide and native copper associated with extensive potassic alteration. K-Na-rich fluids also affected the dolerite in the ‘Paratoo diapir’, resulting in the precipitation of K-feldspar, dravite and K-bearing chabazite-Na. The most likely scenario for the genesis of the Paratoo deposit involves circulation of basinal fluids, focusing into the ‘Paratoo Diapir’, and ore precipitation through neutralization by fluid-rock interaction with the dolomitic shales hosting the mineralization.The Paratoo deposit is deeply weathered, with malachite and chrysocolla (± tenorite and cuprite) containing the bulk of the copper recovered from the shallow workings. A diverse assemblage of secondary REE-bearing carbonate minerals, including the new species decrespignyite-(Y) and paratooite-(La), is associated with the weathered base metal and magnetite ores. Whole-rock geochemical analyses of fresh and mineralized host rock and of vein material reveals that the mineralization is associated with a strong, albeit highly variable, enrichment in light rare earth elements (LREE). This association indicates that REE and base metals were introduced by the same hydrothermal fluid. The strong negative Ce anomaly found in secondary REE minerals and mineralized rock samples suggests an upgrade of the REE contents in the weathering zone, insoluble Ce4+ being left behind.The Fe-oxide-REE-base metal association at Paratoo is also characteristic of the giant Mesoproterozoic Fe oxide copper gold deposit of Olympic Dam, located 350 km to the NW. A similar association is found in the Palaeozoic deposits of the Mt Painter Inlier, 300 km to the NNE. The widespread occurrence of this elemental association in the Province probably reflects the geochemistry of the basement, which contains numerous Mesoproterozoic granites enriched in REE and U.

Organic geochemistry (Rock-Eval) and maturation rank of the Garumnian coal in the Central Pyrenees (Spain)

Fuel ◽  
2000 ◽  
Vol 79 (5) ◽  
pp. 505-513 ◽  
Author(s):  
M. Garcia-Vallès ◽  
M. Vendrell-Saz ◽  
T. Pradell-Cara
Keyword(s):  
Organic Geochemistry ◽  
Rock Eval ◽  
Central Pyrenees

scholarly journals Organic geochemistry and mineralogical characterization of the Paleocene Ranikot Formation shales in selected areas of Southern Indus Basin Pakistan.

2021 ◽  
Author(s):  
Hussain Asghar ◽  
◽  
Saeed Abbas ◽  
Muhammad S. Khan ◽  
Samina Jahandad ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Organic Geochemistry ◽  
Vitrinite Reflectance ◽  
Xrd Analysis ◽  
Indus Basin ◽  
Gas Chromatography Mass Spectrometry ◽  
Mineralogical Characterization ◽  
Type Iv ◽  
Rock Eval

Southern Indus Basin is one of the promising regions in Pakistan as a commercially producing oil and gas perspective. The current research presents the geochemical characterization of the Ranikot Formation shales from Southern Indus Basin based on total organic carbon (TOC), Rock-Eval (RE) pyrolysis, organic petrography, gas chromatography-mass spectrometry (GC-MS), and x-ray diffraction (XRD) analyses. The average TOC of Ranikot shale is 4.6 wt. %, indicating very good hydrocarbon potential. Types III/IV kerogens were identified in Ranikot shale. The maceral data also suggest that the Type of kerogen present in Ranikot shale is dominantly Types II-III, with the minor occurrence of Type IV. The vitrinite reflectance, pyrolysis Tmax and methylphenanthrene indices values specify immature levels of the shales. The normal alkane data reflect that marine macrophyte, algae, and land plants were contributed to the organic matter of Ranikot shales. Dibenzothiophene/phenanthrene ratio (0.11), phytane/n-C18 ratio (0.53), pyrite, and glauconite elucidate that the depositional environment of the Ranikot shale is marine. The XRD analysis of the shale from the Ranikot Formation revealed that it is brittle shale and dominated by 39.5 to 50.9 wt. % quartz. The present study, integration with the US EIA report demarcated the Ranikot Formation influential horizon as a shale gas resource.

scholarly journals Backtracking to Parent Maceral from Produced Bitumen with Raman Spectroscopy

Minerals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 679
Author(s):  
Seyedalireza Khatibi ◽  
Arash Abarghani ◽  
Kouqi Liu ◽  
Alexandra Guedes ◽  
Bruno Valentim ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Organic Matter ◽  
Vitrinite Reflectance ◽  
Thermal Maturity ◽  
Maturity Level ◽  
Production Potential ◽  
Hydrocarbon Production ◽  
Solid Bitumen ◽  
Rock Eval ◽  
Oil Gas

In order to assess a source rock for economical exploitation purposes, many parameters should be considered; regarding the geochemical aspects, the most important ones are the amount of organic matter (OM) and its quality. Quality refers to the thermal maturity level and the type of OM from which it was formed. The origin of the OM affects the ability of the deposited OM between sediments to generate oil, gas, or both with particular potential after going through thermal maturation. Vitrinite reflectance and programmed pyrolysis (for instance, Rock-Eval) are common methods for evaluating the thermal maturity of the OM and its potential to generate petroleum, but they do not provide us with answers to what extent solid bitumen is oil-prone or gas-prone, as they are bulk geochemical methods. In the present study, Raman spectroscopy (RS), as a powerful tool for studying carbonaceous materials and organic matter, was conducted on shale and coal samples and their individual macerals to show the potential of this technique in kerogen typing and to reveal the parent maceral of the examined bitumen. The proposed methodology, by exhibiting the chemical structure of different organic matters as a major secondary product in unconventional reservoirs, can also detect the behavior of solid bitumen and its hydrocarbon production potential for more accurate petroleum system evaluation.

scholarly journals Petrography, Palynology, and Organic Geochemistry of Neogene Paralic Coal, Mukah,Sarawak, Malaysia: Implications For Paleomires, and Peat-Forming Conditions

2021 ◽  
Author(s):  
Nor Syazwani Zainal Abidin ◽  
Khairul Azlan Mustapha ◽  
Wan Hasiah Abdullah ◽  
Zainey Konjing
Keyword(s):  
Organic Geochemistry ◽  
Coal Seams ◽  
Lowland Forest ◽  
Sequence Stratigraphic ◽  
Peat Deposits ◽  
Biomass Loss ◽  
The Rich ◽  
Wet Climate ◽  
Geochemical Analyses ◽  
Water Saturated

Abstract The eight coal seams of Neogene paralic coals from Mukah coalfield, Sarawak, Malaysia, were investigated using petrographical, palynological, and organic geochemical analyses to describe coal-forming vegetation, conditions during peat development and precursor mires, and their associations in a sequence-stratigraphic context. The petrographic data of the coals implies the existence of oxygen-deficient and water-saturated conditions in the precursor mires. The condition of low mire oxidation was followed by biomass loss from the mires. The Mukah coals are suggested to be deposited in freshwater peat swamps, and the rich preservation of angiosperm pollens indicates that the organic matter in dense and lowland forest vegetation was mostly terrigenous. The overwhelming presence of Casuarina and Calamus types, suggesting the paleomires were closely linked to Kerapah/Kerangas peat forest and marginally bordered by rattan and supported by the biomarker data. Rheotrophic–ombrotrophic mires were temporarily formed because of water table fluctuations, which strongly depend on ever-wet climate changes and syn-depositional tectonic during the Neogene, resulting in balanced to high peat accumulation and preservation. A maximum thickness of 35m of peat deposits that formed between 10,000 and 175,000 years ago is suggested. The coals are proposed to be influenced by transgressive to initial highstand cycles within the paralic setting.

GEOCHEMICAL TOOLS FOR EVALUATING PETROLEUM GENERATION IN MIDDLE PROTEROZOIC SEDIMENTS OF THE McARTHUR BASIN, NORTHERN TERRITORY, AUSTRALIA

1994 ◽  
Vol 34 (1) ◽  
pp. 692 ◽  
Author(s):  
Roger E. Summons ◽  
Dennis Taylor ◽  
Christopher J. Boreham
Keyword(s):  
Vitrinite Reflectance ◽  
Land Plant ◽  
Source Rocks ◽  
Hydrocarbon Generation ◽  
Strongly Correlated ◽  
Petroleum Potential ◽  
Petroleum Generation ◽  
Early Palaeozoic ◽  
Geochemical Analyses ◽  
Rock Eval

Maturation parameters based on aromatic hydrocarbons, and particularly the methyl-phenanthrene index (MPI-1), are powerful indicators which can be used to define the oil window in Proterozoic and Early Palaeozoic petroleum source rocks and to compare maturities and detect migration in very old oils . The conventional vitrinite reflectance yardstick for maturity is not readily translated to these ancient sediments because they predate the evolution of the land plant precursors to vitrinite. While whole-rock geochemical tools such as Rock-Eval and TOC are useful for evaluation of petroleum potential, they can be imprecise when applied to maturity assessments.In this study, we carried out a range of detailed geochemical analyses on McArthur Basin boreholes penetrating the Roper Group source rocks. We determined the depth profiles for hydrocarbon generation based on Rock-Eval analysis of whole-rock, solvent-extracted rock, kerogen elemental H/C ratio and pyrolysis GC. Although we found that Hydrogen Index (HI) and the Tmax parameter were strongly correlated with other maturation indicators, they were not sufficiently sensitive nor were they universally applicable. Maturation measurements based on saturated biomarkers were not useful either because of the low abundance of these compounds in most Roper Group bitumens and oils.

scholarly journals Pre-Messinian Deposits of the Mediterranean Ridge: Biostratigraphic and Geochemical Evidence from the Olimpi Mud Volcano Field

Water ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1367
Author(s):  
Anastasios Nikitas ◽  
Maria V. Triantaphyllou ◽  
Grigoris Rousakis ◽  
Ioannis Panagiotopoulos ◽  
Nikolaos Pasadakis ◽  
...  
Keyword(s):  
Organic Matter ◽  
Oil And Gas ◽  
Mud Volcano ◽  
Mud Volcanoes ◽  
Mediterranean Ridge ◽  
The Mediterranean ◽  
Geochemical Analyses ◽  
Mediterranean Ridge Accretionary Complex ◽  
Rock Eval ◽  
Gas Potential

This study presents the results derived from micropaleontological and organic geochemical analyses of mud breccia samples obtained (through gravity coring) from five mud volcanoes (Gelendzhik, Heraklion, Moscow, Milano, Leipzig) located at the Olimpi mud volcano field on the Mediterranean Ridge accretionary complex. A thorough calcareous nannofossil semi-quantitative analysis was performed to determine the biostratigraphic assignment of the deep-seated source strata. Mudstone/shale clasts of different stratigraphic levels were identified and assigned to the Miocene nannofossil biozones CNM10, CNM8–9, CNM7, CNM6–7, and Oligocene CNO4/CNO5. A single mudstone clast from the Gelendzhik plateau, assigned to the biozone CNM10, demonstrated unique micropaleontological and geochemical characteristics, suggesting a sapropelic origin. Subsequently, the total organic carbon (TOC) content and thermal maturity of the collected mud breccias was evaluated using the Rock-Eval pyrolysis technique, and their oil and gas potential was estimated. The pyrolyzed sediments were both organic rich and organic poor (TOC >0.5% or <0.5%, respectively), with their organic matter showing characteristics of the type III kerogen that consists of adequate hydrogen to be gas generative, but insufficient hydrogen to be oil prone. However, the organic matter of the late Serravallian (CNM10) sapropelic mudstone was found to consist of a mixed type II/III kerogen, implying an oil-prone source rock.

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