Re-evaluation of depositional models for the lower Permian Patchawarra Formation, Cooper Basin, South Australia: implications for petroleum exploration

2020 ◽  
Vol 60 (2) ◽  
pp. 794
Author(s):  
Carmine Wainman ◽  
Peter McCabe
Keyword(s):  
Cold Water ◽  
South Australia ◽  
Petroleum Exploration ◽  
Lower Permian ◽  
Time Intervals ◽  
Fine Grained ◽  
Coal Beds ◽  
Hyperpycnal Flows ◽  
Lenticular Bedding ◽  
Cooper Basin

The Late Carboniferous–Triassic Cooper Basin is Australia’s most prolific onshore petroleum province. The lower Permian Patchawarra Formation, which is up to 680 m thick and consists of up to 10% coal, is a major exploration target in the basin. Eighteen cores through the formation have been logged to re-evaluate the existing fluviolacustrine depositional model. The siliciclastics form fining- and coarsening-upward sequences that are 1–10 m thick. They are predominately fine-grained with abundant lenticular bedding, wavy bedding and thinly interlaminated siltstones and clays resembling varves. Granules and pebbles, interpreted as dropstones, are present throughout the formation. Coal beds are up to 60 m thick and rich in inertinite. Other than the coal beds, there is little evidence of the establishment of terrestrial conditions: roots are rare and there are no siliciclastic palaeosols. The siliciclastics are interpreted as the deposits of a large glaciolacustrine system, with the fining-upward successions deposited in subaqueous channels cut by hyperpycnal flows and the coarsening-upward successions deposited as overbank splays between those channels. Hyperpycnal flows may have resulted from sediment-laden cold water emanating from glacially-fed rivers, similar to those seen in many large glacial lakes in high latitudes and altitudes today. Much of the coal is interpreted as the accumulation of peats from floating mires that covered large parts of the glaciolacustrine system at certain time intervals. The high inertinite content of many coals is interpreted as the decay of organic matter within the floating mire. These new interpretations have the potential to enhance reservoir characterisation within the basin.

THE CAMBRIAN PALAEOGEOGRAPHY OF AUSTRALIA AND OPPORTUNITIES FOR PETROLEUM EXPLORATION

1982 ◽  
Vol 22 (1) ◽  
pp. 42 ◽  
Author(s):  
Peter J. Cook
Keyword(s):  
Continental Drift ◽  
Depositional Environments ◽  
Source Rocks ◽  
Petroleum Exploration ◽  
Time Intervals ◽  
Middle Cambrian ◽  
Reservoir Rocks ◽  
Essential Components ◽  
Potential Reservoir ◽  
Cooper Basin

As part of a larger project to re-evaluate the petroleum potential of Australia, it was considered necessary to produce a series of Cambrian palaeogeographic maps. This required the compilation and correlation of a large number of stratigraphic columns, the delineation of sedimentologlcally-significant time intervals, the production of data maps for these same time intervals, and the development of a Cambrian 'tectonic' map. This palaeogeographic study was not undertaken to establish precise exploration targets. However, it does provide new information on where many of the essential components are, what age they are, and why they are there, and as such is a valuable tool in the overall exploration and resource evaluation strategy.The six palaeogeographic maps finally produced illustrate events involving continental drift, tectonics, and climatic and sea-level variations, over a period of 70 million years. Together, these events produced marked changes in the palaeogeography and depositional environments, which in turn profoundly affected the type and distribution of sediments being deposited on and around the palaeo-continent during the Cambrian. Using the palaeogeographic maps and the data accumulated for the project, it is possible to demonstrate that organic-rich sediments, with the potential to be petroleum source rocks, were relatively common during the Cambrian, especially on the eastern cratonic margin during the Lower Cambrian (Officer and possible Amadeus Basins) and the Middle Cambrian (Georgina Basin). There may also be some suitable petroleum source rocks in the Ord Basin. Limestones and dolomites, some of which may constitute potential reservoir rocks, were deposited in a number of Cambrian intracratonic basins (Amadeus, Georgina Basins) and on the shelf (Cooper Basin). Cambrian sandstones in Australia are commonly poor reservoir rocks, but where they have been subjected to shore-line or shelf 'clean-up', for example during the Middle and Upper Cambrian on the northwest side of the craton (Bonaparte Gulf Basin), there may be some potential reservoir rocks. Some sandstones may also be present on the south side of the Cooper Basin. Fine-grained impermeable sediments (potential cap rocks) were deposited throughout the Cambrian, but evaporites were most common during the Early and lower Middle Cambrian. Synsedimentary tectonics may have produced structural and stratigraphlc traps, and a major phase of karsting occurred in the Cambrian. Therefore, the Cambrian of Australia is believed to have many of the prerequisites for the generation, migration and entrapment of hydrocarbons. Especially favourable areas for these features may lie to the southeast of the Georgina Basin and in the offshore region northwest of the Ord and Bonaparte Gulf Basins.

GEOMETRY OF RESERVOIR TRENDS IN THE EPSILON FORMATION SANDS, SOUTHERN COOPER BASIN, SOUTH AUSTRALIA

1992 ◽  
Vol 32 (1) ◽  
pp. 339 ◽  
Author(s):  
W. A. Fairburn
Keyword(s):  
Gamma Ray ◽  
Facies Analysis ◽  
South Australia ◽  
Lower Permian ◽  
Isopach Maps ◽  
Continuous Sheet ◽  
Channel Deposits ◽  
Sand Bodies ◽  
Selection Of ◽  
Cooper Basin

Sandstone reservoirs within the Lower Permian Epsilon Formation, despite being gas productive in several fields in the Cooper Basin of South Australia, in particular Big Lake and Moomba, have proved to be elusive targets for exploration. This is mainly due to the distribution pattern of these sands, which differs markedly from that of the thicker and laterally extensive fluvial sands which are prevalent in the Toolachee and Patchawarra formations. As a consequence, there has been some acceptance that the distribution of Epsilon Formation reservoirs are unpredictable.Log correlation studies of the Epsilon Formation, in conjunction with sand trend mapping, have identified sands which are either laterally continuous ('sheet' sands) or laterally discontinuous ('ribbon' sands).Core facies analysis supports the interpretation that the 'sheet' sands are lake shore strandline deposits whereas the 'ribbon' sands are distributary channel deposits of prograding delta systems.Based on the inferred depositional models, and with the aid of detailed isopach maps, it has been possible to project reservoir trends of the channel sands and prepare sand maps, at varying gamma-ray cutoffs, of the shoreface sands.An understanding of the geometry of the various sand bodies has clarified the prospectivity of the Epsilon Formation and facilitated the selection of development well locations throughout the Southern Cooper Bas

SEISMIC AVO STUDIES ASSIST IN THE MAPPING OF A PERMIAN GAS SAND AT KERNA FIELD, COOPER BASIN

1991 ◽  
Vol 31 (1) ◽  
pp. 244
Author(s):  
J. Pinchin ◽  
A.B. Mitchell
Keyword(s):  
South Australia ◽  
Flood Plain ◽  
Seismic Facies ◽  
Gas Field ◽  
Seismic Modelling ◽  
Coal Beds ◽  
South Central ◽  
Amplitude Versus Offset ◽  
Modelling Studies ◽  
Cooper Basin

Kerna is a gas field within the south-central part of the Cooper Basin, 12 km southwest of the Dullingari Field and adjacent to the border of South Australia and Queensland. The trap is a domal anticline containing gas structurally trapped within the Early Permian Patchawarra Formation. The overlying Permian Epsilon Formation, above intervening shale, also contains gas, which may be stratigraphically trapped or restricted by permeability barriers around the southern and western flanks of the field.Seismic reflection amplitudes can be used to map the extent of the Epsilon gas sand. Seismic modelling studies show that the gas sand displays an amplitude-versus-offset (AVO) effect which distinguishes the gas sand from a wet sand or from a coal reflection at the same stratigraphic level. The spatial distribution of the AVO anomalies, and of the overall seismic stack response, has been mapped across the field. The interpreted 'seismic facies' map shows a meander belt across a coal swamp dominated flood plain. The distribution of AVO anomalies within and around this meander belt shows the likely occurrence of gas-bearing sandstones.This study has implications for other areas of the Cooper Basin where adequate separation between coal beds and gas sands allows the AVO effect of the latter to be observed. These AVO effects can then be used as a direct indicator of gas in stratigraphic and structural traps.

PALYNOLOGIC CONTRIBUTIONS TO PETROLEUM EXPLORATION IN THE PERMIAN FORMATIONS OF THE COOPER BASIN, AUSTRALIA

1969 ◽  
Vol 9 (1) ◽  
pp. 79
Author(s):  
R. J. Paten
Keyword(s):  
Petroleum Exploration ◽  
Upper Permian ◽  
Lower Permian ◽  
Hydrocarbon Accumulation ◽  
Early Permian ◽  
Sufficient Data ◽  
Spores And Pollen ◽  
Eastern Australia ◽  
Biostratigraphic Subdivision ◽  
Cooper Basin

From 1959, when Permian spores and pollen were first identified from Delhi-Santos wells in the Cooper basin until 1967, appreciation of the palynologic succession was impeded by problems associated with the severe carbonization of the microfossils. By 1966, sufficient data had been accumulated for the elucidation of the broad palynologic framework. The Merrimelia Formation was identified as early Permian (palynologic unit Plb of Evans), the Lower and Middle Members of the Gidgealpa Formation as Lower Permian (units Plc-P3a) and the Upper Member of the Formation as Upper Permian (units P3b-P4). Breaks in the microfloral succession were noted above the Merrimelia Formation and between the Middle and Upper Members of the Gidgealpa Formation corresponding with observed litho-stratigraphic hiatuses.Well-preserved microfloras were recovered from four wells in late 1967 and early 1968, and produced a dramatic advance in knowledge of the Permian biostratigraphy. It became possible to relate the microfloral succession to the Permian palynologic stages proposed by Evans (1967), for eastern Australia. The Merrimelia Formation was referred to stage 2, while stages 3, 4 and 5 were recognised within the Gidgealpa Formation. In addition, two units of apparently short duration were recognised in each of stages 4 and 5. A six-fold biostratigraphic subdivision of the entire Permian sequence was thus possible.Palynology is finding wide application to problems encountered in current drilling and stratigraphic investigations. It has shown particular value when applied to those problems associated with the mid-Gidgealpa Formation disconformity, which is an important feature relative to hydrocarbon accumulation in the Gidgealpa Field.

A SHORT HISTORY OF PALEONTOLOGY IN TURKEY, PART I: FROM THE NINETEENTH CENTURY TO THE COLLAPSE OF OTTOMAN TURKEY

2021 ◽  
Vol 40 (1) ◽  
pp. 158-201
Author(s):  
VOLKAN SARIGÜL
Keyword(s):  
Nineteenth Century ◽  
Petroleum Exploration ◽  
Stratigraphic Analysis ◽  
Coal Beds ◽  
Geological Processes ◽  
Natural History Collection ◽  
History Of ◽  
Ottoman Turkey ◽  
The Rich ◽  
Military Engineering

ABSTRACT Modern paleontology in Turkey appeared in the early nineteenth century, together with the first modern geological studies. The fossils collected in these studies were initially used to establish biostratigraphy and to make the first geological maps of the country. Paleontologists were involved in these studies from the beginning; the earliest identifications of new animal and plant taxa from Turkey occurred in the same century along with the detailed descriptions of the rich and diverse Turkish fossil record. Aside from the academic studies, some paleontologists also took part in the economic side by contributing to stratigraphic analysis of coal beds or participating in petroleum exploration. All these pioneering works on the geology and paleontology of Turkey were done by foreigners; however, the outcomes of this newly introduced science were quickly appreciated by Ottoman Turkey. During the middle of the nineteenth century, the first text mentioning geological processes was written by the head scholar of the Imperial School of Military Engineering, while the first geology classes began to be taught under the Imperial Medical School in Istanbul, in which the first natural history collection was also established. Unfortunately, not a single original study in paleontology was produced by Ottoman citizens, with the notable exception of an Austrian immigrant of Hungarian descent, possibly because of a lack of a real interest in earth sciences.

Exploring for stratigraphic traps in the Patchawarra Formation, Cooper Basin: an integrated seismic methodology

2018 ◽  
Vol 58 (2) ◽  
pp. 779
Author(s):  
Alexandra Bennett
Keyword(s):  
Complex Geometry ◽  
Imaging Techniques ◽  
South Australia ◽  
Seismic Interpretation ◽  
Seismic Survey ◽  
3D Seismic ◽  
Seismic Resolution ◽  
Seismic Reflectivity ◽  
Seismic Area ◽  
Cooper Basin

The Patchawarra Formation is characterised by Permian aged fluvial sediments. The conventional hydrocarbon play lies within fluvial sandstones, attributed to point bar deposits and splays, that are typically overlain by floodbank deposits of shales, mudstones and coals. The nature of the deposition of these sands has resulted in the discovery of stratigraphic traps across the Western Flank of the Cooper Basin, South Australia. Various seismic techniques are being used to search for and identify these traps. High seismic reflectivity of the coals with the low reflectivity of the relatively thin sands, often below seismic resolution, masks a reservoir response. These factors, combined with complex geometry of these reservoirs, prove a difficult play to image and interpret. Standard seismic interpretation has proven challenging when attempting to map fluvial sands. Active project examples within a 196 km2 3D seismic survey detail an evolving seismic interpretation methodology, which is being used to improve the delineation of potential stratigraphic traps. This involves an integration of seismic processing, package mapping, seismic attributes and imaging techniques. The integrated seismic interpretation methodology has proven to be a successful approach in the discovery of stratigraphic and structural-stratigraphic combination traps in parts of the Cooper Basin and is being used to extend the play northwards into the 3D seismic area discussed.

scholarly journals Reservoir quality and its controlling diagenetic factors in the Bentiu Formation, Northeastern Muglad Basin, Sudan

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yousif M. Makeen ◽  
Xuanlong Shan ◽  
Mutari Lawal ◽  
Habeeb A. Ayinla ◽  
Siyuan Su ◽  
...  
Keyword(s):  
Clay Content ◽  
Petroleum Exploration ◽  
Reservoir Quality ◽  
Burial Depth ◽  
Petroleum Reservoir ◽  
Fine Grained ◽  
Porosity And Permeability ◽  
Negative Role ◽  
Crevasse Splay ◽  
Channel Deposits

AbstractThe Abu Gabra and Bentiu formations are widely distributed within the interior Muglad Basin. Recently, much attention has been paid to study, evaluate and characterize the Abu Gabra Formation as a proven reservoir in Muglad Basin. However, few studies have been documented on the Bentiu Formation which is the main oil/gas reservoir within the basin. Therefore, 33 core samples of the Great Moga and Keyi oilfields (NE Muglad Basin) were selected to characterize the Bentiu Formation reservoir using sedimentological and petrophysical analyses. The aim of the study is to de-risk exploration activities and improve success rate. Compositional and textural analyses revealed two main facies groups: coarse to-medium grained sandstone (braided channel deposits) and fine grained sandstone (floodplain and crevasse splay channel deposits). The coarse to-medium grained sandstone has porosity and permeability values within the range of 19.6% to 32.0% and 1825.6 mD to 8358.0 mD respectively. On the other hand, the fine grained clay-rich facies displays poor reservoir quality as indicated by porosity and permeability ranging from 1.0 to 6.0% and 2.5 to 10.0 mD respectively. A number of varied processes were identified controlling the reservoir quality of the studies samples. Porosity and permeability were enhanced by the dissolution of feldspars and micas, while presence of detrital clays, kaolinite precipitation, iron oxides precipitation, siderite, quartz overgrowths and pyrite cement played negative role on the reservoir quality. Intensity of the observed quartz overgrowth increases with burial depth. At great depths, a variability in grain contact types are recorded suggesting conditions of moderate to-high compactions. Furthermore, scanning electron microscopy revealed presence of micropores which have the tendency of affecting the fluid flow properties in the Bentiu Formation sandstone. These evidences indicate that the Bentiu Formation petroleum reservoir quality is primarily inhibited by grain size, total clay content, compaction and cementation. Thus, special attention should be paid to these inhibiting factors to reduce risk in petroleum exploration within the area.

A petrographic study of the Rotliegendes Sandstone reservoir (Lower Permian) in the Rough Gas Field

Clay Minerals ◽  
1986 ◽  
Vol 21 (4) ◽  
pp. 459-477 ◽  
Author(s):  
M. W. Goodchild ◽  
J. H. McD. Whitaker
Keyword(s):  
Sedimentary Facies ◽  
Mineral Dissolution ◽  
Lower Permian ◽  
Secondary Porosity ◽  
Gas Field ◽  
Thin Sections ◽  
Fine Grained ◽  
Groundwater Movement ◽  
Marked Variability ◽  
Sandstone Reservoir

AbstractThe diagenetic history of the Rotliegendes Sandstone reservoir in the Rough Gas Field was studied using thin-sections, XRD analyses and SEM. The Rotliegendes comprises a sequence of fine-grained fluvial sheet-flood sandstones and coarse, gravelly, low-sinuosity channel sandstones, with thin aeolian interbeds, overlain by a sequence of aeolian dune and interdune sandstones. Early, environmentally-related diagnesis (eogenesis) shows a marked variability with sedimentary facies. Within aeolian sandstones, poikilotopic anhydrite and fine, rhombic dolomite are preserved. Fluvially-derived sandstones typically contain infiltrated detrital clays and early authigenic mixed-layer clays, together with coarse, framework-displacive dolomite. Feldspars show varying degrees of alteration within all facies. These eogenetic features reflect patterns of groundwater movement during the Rotliegendes and early Zechstein. Mineral dissolution and precipitation were controlled by the chemistry of the groundwaters. Burial diagenetic (mesogenetic) features are superimposed on eogenetic cements. Authigenic clays have been converted to illitic clays. In addition, mesogenetic chlorite has formed and quartz and strongly ferroan dolomite cements are recognized. These minerals may be related to clay diagenesis within the underlying Carboniferous Coal Measures. Early, framework-supporting anyhdrite, and both phases of dolomite, have been partially dissolved, creating secondary porosity. This is attributed to the action of acidic porewaters, generated by the maturation of organic material within the Carboniferous. Post-dissolution kaolinite, gypsum and minor pyrite infill secondary pores. Gas emplacement from the Late Cretaceous onwards effectively halted further diagenetic reactions.

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