LOWER CAMBRIAN RELIEF SANDSTONE, EASTERN OFFICER BASIN, SOUTH AUSTRALIA: AN EXAMPLE OF ECONDARY POROSITY DEVELOPMENT

1990 ◽  
Vol 30 (1) ◽  
pp. 184
Author(s):  
Chris J. Gaughan ◽  
John K. Warren
Keyword(s):  
South Australia ◽  
Source Rocks ◽  
Reservoir Quality ◽  
The West ◽  
Potential Source ◽  
Lower Reservoir ◽  
Close Proximity ◽  
Porosity And Permeability ◽  
Fluvial Environments ◽  
Live Oil

Interest in the Relief Sandstone as a potential economic oil-bearing sandstone is supported by excellent reservoir quality (up to 26.6 per cent porosity and 4839 md permeability). Potential source rocks are found above, below and interfingering with the Relief Sandstone. There are several occurrences of live oil bleeding from vugs and fractures in a stratigraphically higher carbonate. Traces of oil in the Relief sands, and the presence of live oil in relatively close proximity, suggests that the Relief Sandstone could host an economic oil accumulation.The majority of the Relief Sandstone was deposited in aeolian or braided fluvial environments with some tidal to shallow marine deposition in the west. Distribution of reservoir-quality sands is bimodal. In the east, porosity and permeability for the most part is very poor to average. In the west, porosity and permeability is generally good to excellent. The bulk of the economic porosity is secondary, a result of dissolution of cement and matrix, with minor porosity from leaching of grains. The lower reservoir quality in the east is due to diagenesis associated with compaction and authigenic illite. In the west, the porosity and permeability are high and generally due to dissolution of clay cement and primary matrix. In some cases where the clay has undergone less dissolution, it remains as grain rims and still blocks pore throats. This significantly reduces permeability although the porosity may remain high.

A REVIEW OF RECENT GEOLOGICAL WORK IN THE OFFICER BASIN, SOUTH AUSTRALIA

1980 ◽  
Vol 20 (1) ◽  
pp. 209 ◽  
Author(s):  
G.M. Pitt ◽  
M.C. Benbow ◽  
Bridget C. Youngs
Keyword(s):  
South Australia ◽  
Source Rocks ◽  
Organic Carbon Content ◽  
Petroleum Potential ◽  
Geological Surveys ◽  
Potential Source ◽  
Potential Reservoir ◽  
Carbonate Sequence ◽  
Geological Work ◽  
Australian Department

The Officer Basin of South and Western Australia, in its broadest definition, contains a sequence of Late Proterozoic to pre-Permian strata with an unknown number of stratigraphic breaks. Recent investigations by the South Australian Department of Mines and Energy (SADME), which included helicopter-based geological surveys and stratigraphic drilling, have upgraded the petroleum potential of the basin.SADME Byilkaoora-1, drilled in the northeastern Officer Basin in 1979, contained hydrocarbon shows in the form of oil exuding from partly sealed vugs and fractures in argillaceous carbonates. Equivalent carbonates were intersected in SADME Marla-1A and 1B. Previously, in 1976, SADME Murnaroo-1 encountered shales and carbonates with moderate organic carbon content overlying a thick potential reservoir sandstone, while SADME Wilkinson-1, drilled in 1978, contained a carbonate sequence with marginally mature to mature oil-prone source rocks. Acritarchs extracted from the last mentioned carbonates indicate an Early Cambrian age.All ?Cambrian carbonate sequences recognised to date in the Officer Basin of South Australia are correlated with the Observatory Hill Beds, which are now considered to be the major potential source of petroleum in the eastern Officer Basin.

OIL GEOCHEMISTRY AND POTENTIAL SOURCE ROCKS OF THE OFFICER BASIN, SOUTH AUSTRALIA

1980 ◽  
Vol 20 (1) ◽  
pp. 68 ◽  
Author(s):  
D.M. McKirdy ◽  
A.J. Kantsler
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Carbonate Rocks ◽  
Depositional Environment ◽  
South Australia ◽  
Source Rocks ◽  
Potential Source ◽  
Playa Lake ◽  
Oil Source ◽  
Extractable Organic Matter

Oil shows observed in Cambrian Observatory Hill Beds, intersected during recent stratigraphic drilling of SADME Byilkaoora-1 in the Officer Basin, indicate that oil has been generated within the basin. Shows vary in character from "light" oils exuding from fractures through to heavy viscous bitumen in vugs in carbonate rocks of a playa-lake sequence.The oils are immature and belong to two primary genetic families with some oils severely biodegraded. The less altered oils are rich in the C13 - C25 and C30 acyclic isoprenoid alkanes. Source beds within the evaporitic sequence contain 0.5 - 1.0% total organic carbon and yield up to 1900 ppm solvent-extractable organic matter. Oil-source rock correlations indicate that the oils originated within those facies drilled; this represents the first reported examples of non-marine Cambrian petroleum. The main precursor organisms were benthonic algae and various bacteria.Studies of organic matter in Cambrian strata from five other stratigraphic wells in the basin reveal regional variations in hydrocarbon source potential that relate to differences in precursor microbiota and/or depositional environment and regional maturation. Micritic carbonates of marine sabkha origin, located along the southeast margin of the basin, are rated as marginally mature to mature and good to prolific sources of oil. Further north and adjacent to the Musgrave Block, Cambrian siltstones and shales have low organic carbon values and hydrocarbon yields, and at best are only marginally mature. Varieties of organic matter recognised during petrographic studies of carbonates in the Officer Basin include lamellar alginite (alginite B) and "balls" of bitumen with reflectance in the range 0.2 to 1.4%.

SEQUENCE STRATIGRAPHY OF THE EASTERN OFFICER AND ARROWIE BASINS: A FRAMEWORK FOR CAMBRIAN OIL SEARCH

1991 ◽  
Vol 31 (1) ◽  
pp. 177 ◽  
Author(s):  
D. I. Gravestock ◽  
J.E. Hibburt
Keyword(s):  
Carbonate Reservoir ◽  
Source Rocks ◽  
Tectonic Activity ◽  
Reservoir Quality ◽  
Organic Carbon Content ◽  
The North ◽  
Subaerial Exposure ◽  
Potential Source ◽  
Shelf Slope ◽  
Playa Lake

The Early Cambrian eastern Officer and Arrowie Basins share a common sequence stratigraphic framework despite their contrasting settings. The Arrowie Basin was initially a shallow marine shelf between two land masses with moderate to abrupt shelf-ramp and shelf-slope profiles deepening to the north and south. Tectonic activity subsequently restricted open marine access to the north resulting in evaporite and red bed deposition. In the eastern Officer Basin epeiric sea sediments had open marine access only to the northeast. The palaeoslope was low and surrounding land supplied abundant siliciclastics. Following marine withdrawal alkaline playa lake and evaporitic mudflat deposits spread across the hinterland. Potential source rocks in the Arrowie Basin are thick transgressive and early high-stand deposits of the lowest three sequences. Organic carbon content may be highest (on slender evidence) where marine circulation was restricted. Carbonate reservoir quality on the shelf depends on subaerial exposure during marine lowstands. Prograding highstand sands, carbonate grainstones, and syntectonic channel deposits have untested reservoir potential. In the eastern Officer Basin potential source rocks are thin but widespread. Oil has been generated in the playa lake sediments. Fluvial, aeolian and shoreline sandstones, and those interbedded with carbonates, have excellent reservoir characteristics. The interbedded sands are thin but may be grouped near sequence boundaries. Lowstand carbonate breccias have generally unpredictable reservoir quality. Major differences in source and reservoir bed distribution between these basins, which share the same cycles of relative sea level change, are: palaeoslope, proximity to open marine conditions, duration of subaerial exposure and availability of terrigenous clastics.

PROSPECTIVITY AND EXPLORATION HISTORY OF THE BARROW SUB-BASIN, WESTERN AUSTRALIA

1997 ◽  
Vol 37 (1) ◽  
pp. 117 ◽  
Author(s):  
P.W. Baillie ◽  
E.P. Jacobson
Keyword(s):  
Lower Cretaceous ◽  
Source Rocks ◽  
Reservoir Quality ◽  
Liquid Hydrocarbons ◽  
Reservoir Rocks ◽  
Long Period ◽  
Porosity And Permeability ◽  
History Of ◽  
Hydrocarbon Reserves

The Carnarvon Basin is Australia's leading producer of both liquid hydrocarbons and gas. Most oil production to date has come from the Barrow Sub-basin. The success of the Sub-basin is due to a fortuitous combination of good Mesozoic source rocks which have been generating over a long period of time, Lower Cretaceous reservoir rocks with excellent porosity and permeability, and a thick and effective regional seal.A feature of Barrow Sub-basin fields is that they generally produce far more petroleum than is initially estimated and booked, a result of the excellent reservoir quality of the principal producing reservoirs.Structural traps immediately below the regional seal (the 'top Barrow play') have been the most successful play to date. Analysis of 'new' and 'old' play concepts show that the Sub-basin has potential for significant additional hydrocarbon reserves.

STUDIES ON PETROLEUM GEOLOGY AND GEOCHEMISTRY, MIDDLE PROTEROZOIC, McARTHUR BASIN NORTHERN AUSTRALIA I: PETROLEUM POTENTIAL

1988 ◽  
Vol 28 (1) ◽  
pp. 283 ◽  
Author(s):  
J- Jackson ◽  
I. P. Sweet ◽  
T. G. Powell
Keyword(s):  
Source Rocks ◽  
Coarse Grained ◽  
Hydrocarbon Generation ◽  
Petroleum Potential ◽  
Potential Source ◽  
Quartz Arenite ◽  
Abundant Evidence ◽  
Potential Reservoir ◽  
Fluvial Environments ◽  
Middle Proterozoic

Mature, rich, potential source beds and adjacent potential reservoir beds exist in the Middle Proterozoic sequence (1400-1800 Ma) of the McArthur Basin. The McArthur and Nathan Groups consist mainly of evaporitic and stromatolitic cherty dolostones interbedded with dolomitic siltstone and shale. They were deposited in interfingering marginal marine, lacustrine and fluvial environments. Lacustrine dolomitic siltstones form potential source beds, while potential reservoirs include vuggy brecciated carbonates associated with penecontemporaneous faulting and rare coarse-grained clastics. In contrast, the younger Roper Group consists of quartz arenite, siltstone and shale that occur in more uniform facies deposited in a stable marine setting. Both source and reservoir units are laterally extensive (over 200 km).Five potential source rocks at various stages of maturity have been discovered. Two of these source rocks, the lacustrine Barney Creek Formation in the McArthur Group and the marine Velkerri Formation in the Roper Group, compare favourably in thickness and potential with rich demonstrated source rocks in major oil-producing provinces. There is abundant evidence of migration of hydrocarbons at many stratigraphic levels. The geology and reservoir characteristics of the sediments in combination with the distribution of potential source beds, timing of hydrocarbon generation, evidence for migration and chances of preservation have been used to rank the prospectivity of the various stratigraphic units in different parts of the basin.

The Lower Triassic Caley Member: depositional facies, reservoir quality and seismic expression

2018 ◽  
Vol 58 (2) ◽  
pp. 878 ◽  
Author(s):  
Jack Woodward ◽  
Jon Minken ◽  
Melissa Thompson ◽  
Margarita Kongawoin ◽  
Laurence Hansen ◽  
...  
Keyword(s):  
Seismic Data ◽  
Lower Triassic ◽  
Source Rocks ◽  
Geochemical Data ◽  
Reservoir Quality ◽  
Depositional Facies ◽  
Efficient System ◽  
Delta Plain ◽  
Porosity And Permeability ◽  
Thin Reservoir

Recent exploration success in the Lower Keraudren Formation of the Bedout sub-basin has resulted in the emergence of the Caley Member reservoirs (Thompson et al. 2018). The interplay of several unique characteristics at this stratigraphic level are favourable for the generation, trapping and deliverability of hydrocarbons. These unique characteristics include, the preservation of porosity and permeability at depths greater than 4000 m, an organic-rich delta-plain lagoon mudstone source rock interbedded with the reservoir and the presence of a thick hemi-pelagic shale. This proximity of the mature source rocks and reservoir quality units combined with a thick overlying shale has created a highly efficient system for trapping hydrocarbons. Seismic data is a key tool to help unlock this play. Seismic imaging of a relatively thin reservoir at a depth below 4000 m has proved challenging. Quadrant has undertaken several stages of reprocessing and conducted multiple seismic inversions to better image and predict the reservoir. Integration and interpretation of geophysical, geological and geochemical data of this recently discovered reservoir has increased Quadrant’s understanding of the potential of the under-explored Bedout sub-basin.

THE BASIC TYPES OF SECONDARY CHANGES IN RESERVOIR ROCKS IN THE TERRITORY OF THE WEST SIBERIA PLATE

2015 ◽  
pp. 26-30
Author(s):  
A. V. Podnebesnykh ◽  
S. V. Kuznetsov ◽  
V. P. Ovchinnikov
Keyword(s):  
Oil Recovery ◽  
West Siberia ◽  
Recovery Factor ◽  
Change Processes ◽  
The West ◽  
Reservoir Rocks ◽  
Tectonically Active ◽  
Porosity And Permeability ◽  
Active Zones ◽  
Regional Character

On the example of the group of fields in the West Siberia North the basic types of secondary changes in reservoir rocks are reviewed. Some of the most common types of such changes in the West Siberian plate territory include the processes of zeolitization, carbonation and leaching. These processes have, as a rule, a regional character of distribution and are confined to the tectonically active zones of the earth's crust. Due to formation of different mineral paragenesises the secondary processes differently affect the reservoir rocks porosity and permeability: thus, zeolitization and carbonization promote to reducing the porosity and permeability and leaching improvement. All this, ultimately leads to a change of the oil recovery factor and hydrocarbons production levels. Study and taking into account of the reservoir rocks secondary change processes can considerably influence on placement of operating well stock and on planning of geological and technological actions.

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