THE USE OF GAS ISOTOPES IN DETERMINING THE SOURCE OF SOME GIPPSLAND BASIN OILS

1984 ◽  
Vol 24 (1) ◽  
pp. 217
Author(s):  
B. J. Burns A. T. James ◽  
J.K. Emmett
Keyword(s):  
Late Cretaceous ◽  
Isotopic Separation ◽  
Gippsland Basin ◽  
Paraffinic Oil ◽  
Gas Isotopes

The technique of determining the level of maturity of a gas by using the isotopic separation between its hydrocarbon components has been applied to gases flashed from undersaturated Gippsland Basin oils. The results suggest that the Gippsland Basin oils have been generated at an LOM of 11-12. Fluviatile shales of Late Cretaceous age at depths of around 3900 m are interpreted as being the source for much of the paraffinic oil discovered to date.

A NEW MODEL FOR THE MID-CRETACEOUS STRUCTURAL HISTORY OF THE NORTHERN GIPPSLAND BASIN

1991 ◽  
Vol 31 (1) ◽  
pp. 143 ◽  
Author(s):  
D.C. Lowry ◽  
I.M. Longley
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Second Phase ◽  
Northern Flank ◽  
Tectonic History ◽  
Structural History ◽  
Intermittent Compression ◽  
History Of ◽  
Transfer Faults ◽  
Gippsland Basin

The tectonic history of the northern flank of the offshore Gippsland Basin can be divided into three phases:an Early Cretaceous rift phase (120-98 Ma) with deposition of the Strzelecki Group and extension in a northeast-southwest direction.a mid-Cretaceous phase (98-80 Ma) with deposition of the Golden Beach Group and extension in a northwest- southeast direction anda Late Cretaceous to Tertiary sag phase with intermittent compression or wrenching.Previous workers have described the first and third phases. This paper argues for a distinctive second phase with extension at right angles to the first phase. The complex Cretaceous structure in the Kipper-Hammerhead area is interpreted in terms of a model in which transfer faults of the first phase became domino faults of the second phase.

GIPPSLAND'S OLD AND NEW OIL

1977 ◽  
Vol 17 (2) ◽  
pp. 47
Author(s):  
B.R. Brown
Keyword(s):  
Late Cretaceous ◽  
Oil And Gas ◽  
Sediment Supply ◽  
Associated Gas ◽  
Fine Grained ◽  
Early Oligocene ◽  
Gas Fields ◽  
Potential Traps ◽  
Gippsland Basin ◽  
Western Portion

The Gippsland Basin, initiated in the late Cretaceous, accumulated as much as 4,500 m. (15,000 feet) of sediment before the first major structural movement in the early Eocene, when faulted anticlinal structures and pronounced regional westerly dip were developed in the Latrobe Group.Over the next 13 m.y. of the Eocene, sediment supply was reduced and much of it trapped in the western portion of the basin. On the eastern marine edge of the basin the Tuna-Flounder Channel was cut and filled over a period of 4 m.y. Subsequent erosion, sometimes severe, particularly in the Marlin area, created the significant unconformity on top of the Latrobe Group reservoir sediments. Much of that surface was covered with fine-grained marine sediment of early Oligocene age, leaving only a few high-standing areas unsealed for a further period of 25 m.y. until the mid-Miocene.Later structural movements, in the mid-Miocene (10 m.y.B.P.), were largely vertical with some anticlinal warping. New potential traps were created then and some older structures rejuvenated. Following the latter period of anticlinal growth, a major marine channel system was formed by erosion 9 m.y.B.P. and subsequently engulfed by rapid deposition of prograded wedges of sediment on the continental margin.Oil and gas have been formed from land-derived organic matter deposited in the Latrobe Group during late Cretaceous to Eocene times (100.37 m.y.). Subsequently the oil and gas accumulations have developed their distinctive geographical distribution with the major oil fields buried deeper than the major gas fields. It appears that oil has migrated and been trapped at intervals over the last 60 m.y. under varying overburdens from about 100 m. to about 2,000 m. as indicated by the saturation pressures of the crude oils. Migration of oil into the Kingfish and Halibut fields apparently took place no later than 10 to 24 m.y.B.P. Gas migration into Marlin and associated gas fields took place later. There is evidence that oil and gas is forming at present, leading to the conclusion that both old and new oil exist in the basin.

PETROLEUM OCCURRENCE IN THE GIPPSLAND BASIN AND ITS RELATIONSHIP TO RANK AND ORGANIC MATTER TYPE

1984 ◽  
Vol 24 (1) ◽  
pp. 196 ◽  
Author(s):  
G. C. S Smith ◽  
A. C. Cook
Keyword(s):  
Organic Matter ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Late Eocene ◽  
Generative Capacity ◽  
Near Surface ◽  
Metamorphic History ◽  
Downhole Temperature ◽  
Gippsland Basin ◽  
Sediment Age

Coal rank, sediment age and downhole temperature data indicate that the rates of burial and palaeothermal gradients in the Gippsland Basin have varied both areally and with time over the Late Cretaceous to Recent period. The generation and occurrence of petroleum are controlled mainly by the burial metamorphic history. The inshore areas are gas prone because the Late Cainozoic burial meta-morphism is moderate and overprints an earlier phase of substantial burial metamorphism in the Late Cretaceous-Early Tertiary. The areas offshore in the Central Deep are oil prone because the earlier burial metamorphism was minor and the burial metamorphism during the last 20 Ma has been rapid and substantial.Vitrinite reflectance values (R̅vmax) vary from about 0.2 per cent at near-surface depths to over 1.2 per cent in the Upper Cretaceous sediments at depths of about 4 km and more. Exinite reflectance values (R̅emax) are about 0.05 per cent at near-surface depths increasing gradually to only 0.15 per cent at 3 km. Significant exinite metamorphism is evident at depths between 3 and 4 km, with major exinite metamorphism at 4-5 km and more at the base of the Upper Cretaceous sequence.The proportion of organic matter and its specific generative capacity increases up through the Latrobe Group. The Late Cretaceous to Early Eocene organic matter consists of orthohydrous vitrinite and diverse inertinite and is distinct from the Middle to Late Eocene coaly matter which consists of perhydrous vitrinite and minor amounts of inertinite. The Oligocene to Miocene organic matter is dominated by perhydrous vitrinites and is inertinite-poor. The overall proportion of exinite is roughly constant up through the Upper Cretaceous to Miocene terrestrial sequences although some forms of alginite are more common in the Eocene to Miocene sediments. Petrographic and geologic evidence suggests that much of the petroleum probably is generated from vitrinite in addition to exinite at low coal ranks (R̅vmax 0.4-0.8 per cent) and low burial depths (2-4 km).

GEOLOGIC EVOLUTION AND HYDROCARBON HABITAT GIPPSLAND BASIN

1972 ◽  
Vol 12 (1) ◽  
pp. 132 ◽  
Author(s):  
J. Barry Hocking
Keyword(s):  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Meteoric Water ◽  
Oil And Gas ◽  
Basin Evolution ◽  
Fold Belt ◽  
Apparent Lack ◽  
Northern Flank ◽  
Southeastern Australia ◽  
Gippsland Basin

The Gippsland Basin of southeastern Australia is a post-orogenic, continental margin type of basin of Upper Cretaceous-Cainozoic age.Gippsland Basin evolution can be traced back to the establishment of the Strzelecki Basin, or ancestral Gippsland Basin, during the Jurassic. Gippsland Basin sedimentation commenced in the middle to late Cretaceous and is represented as a gross transgressive-regressive cycle consisting of the continental Latrobe Valley Group (Upper Cretaceous to Eocene or Miocene), the marine Seaspray Group (Oligocene to Pliocene or Recent), and finally the continental Sale Group (Pliocene to Recent).The hydrocarbons of the Gippsland Shelf petroleum province were generated within the Latrobe Valley Group and are trapped in porous fluvio-deltaic sandstones of the Latrobe. At Lakes Entrance, however, oil and gas are present in a marginal sandy facies of the Lakes Entrance Formation (Seaspray Group).The buried Strzelecki Basin has played a fundamental role in the development and distribution of the Cainozoic fold belt in the northern Gippsland Basin. The Gippsland Shelf hydrocarbon accumulations fall within this belt and are primarily structural traps. The apparent lack of structural accumulations onshore in Gippsland is largely due to a Plio-Pleistocene episode of cratonic uplift that was accompanied by basinward tilting of structures and meteoric water influx.The non-commercial Lakes Entrance field, located on the stable northern flank of the basin, is a stratigraphic trap and may serve as a guide for future exploration.

A NEW PLAY IN THE GIPPSLAND BASIN

1987 ◽  
Vol 27 (1) ◽  
pp. 164 ◽  
Author(s):  
David C. Lowry
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Before Present ◽  
Angular Unconformity ◽  
Seismic Sections ◽  
Gippsland Basin

Explorers of the Cippsland Basin have generally assumed that the prospective Latrobe Group (Late Cretaceous to Eocene) is separated from the Strzelecki Group (Early Cretaceous) by an angular unconformity dated at about 100 million years before present (Ma). Thus all sub-unconformity traps seen on seismic sections have been assumed to be developed in the unprospective Strzelecki Group. Evidence from seismic sections and wells indicates that this unconformity should be dated at about 80 Ma. The beds deposited between 80 and 100 Ma are part of the Late Cretaceous Latrobe Group and have the potential for both reservoirs and intraformational seals.This new sub-unconformity play can be pursued in areas transitional between the Central Deep and the flanking platforms. On the platforms the prospective beds are absent because of truncation while in the Central Deep they are beyond the reach of the drill.

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