摘要:

Substantial published and unpublished data contradict accepted laws of organic metamorphism. Significant amounts of C15+hydrocarbons and kerogen with significant generation potential exist in sediments which have been buried at high temperatures for long periods of geologic time. Graphite formation and greenschist metamorphism do not occur at model‐predicted burial times and temperatures. Maturation levels for sediments with long (up to 240 million years) burial times are much lower than expected, and conversely, higher than expected for sediments with short (2 million years) burial times. The threshold of intense petroleum generation is not detectable in Plio‐Miocene sediments at minimum temperatures of 160° C.Literature examination reveals that the only solid documentation of time as a controlling parameter in organic metamorphism is in the works of Karweil (1955), Lopatin (1971) and Connan (1974). Scrutiny of these authors' study areas reveals that all have had moderate to extreme paleogeothermal gradients from incipient and aborted rifting, extrusive and intrusive igneous activity, hydrothermal activity, orogenesis and/or uplift and erosion. Levels of organic metamorphism attributed to geologic time by the above authors are better explained by high paleogeothermal gradients resulting from major geologic activity.Mean vitrinite reflectance (RO) data have been compiled from different sedimentary basins currently at or near maximum geothermal gradients with sediment burial times ranging from 2–240 million years. The ROdata from these basins show a strong correlation (r = 0.97) of increase in R, with increase in temperature. These same data show no correlation of increasing Ro with increasing burial times for any temperature interval. R, data from sedimentary basins affected by high‐temperature geothermal systems with heating times of only 1,000–10,000 years overlie R, data from these petroleum‐bearing sedimentary basins with burial (heating) times of 2–240 million years.Contrary to accepted thought, there is no evidence from the natural system that petroleum generation‐maturation reactions have first‐order reaction kinetics. By contrast, a substantial body of evidence from petroleum generation‐maturation laboratory studies carried out in closed water‐ wet systems show that these reactions are characterized by multiple‐order reaction kinetics.Geologically older sediments clearly tend to be more organically mature than younger sediments at the same burial temperatures. However, this correlation ismorea reflection that older sediments have had a greater chance of being affected by a major geologic event with an accompanying high heat flow. The major conclusions of this paper are that: (1) geologic time has no observable effect on organic metamorphism; (2) vitrinite reflectance can be used as an absolute paleogeothermorneter; and (3) the accepted models of organic metamorphism at the very least n

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00260.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Source rock abundance through geological time cannot be measured in absolute quantitative terms. The source rocks of giant fields, which are known in most cases, can serve as an appropriate yardstick for a percentage allocation of source rocks to geological time intervals, based on ultimately recoverable reserves. This yardstick is used to relate source rock percentages per time interval to in situ reserves and resources of oil and gas worldwide, both conventional and unconventional. Necessary corrections are made. On this basis it appears that the Cretaceous is the most important oil‐generating period (49%), while the Tertiary is the most important gas‐generating period (76%). For total hydrocarbons in terms of oil equivalents, the most important hydrocarbon‐generating intervals are the Tertiary (69%), followed by the Cretaceous (25%), the Jurassic (4%) and the Triassic to Paleozoic (2%). The percentages refer to source‐rock age and not to time of generation. All estimates have to be regarded with much caution. They represent an approach to the problem rather than a solution. Major uncertainties still exist. It must be stressed that the problem of source rock abundance should be seen in a wider hydrocarbon habitat context, especially in the light of retention. The important role of bacterial gas and gas hydrates is emp

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00261.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Analyses of recent carbonate sediments of a wide variety of textural types reveal organic carbon content of 0.98–5.23 wt.% which are well above the 0.3 wt.% minimum requirement for carbonate sediments to be considered potential source deposits.The organic facies consist dominantly of autochthonous marine organic matter, both particulate and dissolved, which is highly pyrolysis‐degradable. Under the correct conditions of burial, temperature and probably catalysis (despite the general absence of clays), commercially‐significant hydrocarbons would be generated and would accumulate as petroleum in those rocks that possess the necessary effective porosity.This concept of the origin of petroleum in carbonate rocks affords an explanation for the exceptionally rich petroleum accumulations in porous carbonate rocks; it is also consistent with the stratigraphic habitats of most hydrocarbon pools in carbonate petroliferous prov

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00262.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Paradoxical as it may seem, Kuwait is part of one of the least explored oil‐producing regions on Earth. Contrary to common misconceptions, it has yet to complete the exploration of its hydrocarbon resources.Due to various factors, a few local and scanty regional studies of the petroleum geology of Kuwait have now been completed by various establishments. Regional studies were based mainly on unevenly distributed and widely spaced control points. They invariably recommended further studies.It stands to reason that future regional studies should adopt an alternative approach, or otherwise end‐up with similar conclusi

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00263.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Plate tectonics continues to dominate geological thinking; the main object of this paper is to explain salt movements due to halokinesis in terms of plate kinematics. A term “halokinematics” is proposed by the author to define disturbances ofsaltflo w caused by continuous indirect geologic events which might be a consequence of plate kinematics. Salt rocks constitute the caprock ofdetrital Upper Triassic reservoirs in the NCzone of Algeria whereas eruptive rocks, mainly basalts andspilites, constitute the cap‐rock of the lowermost series to the SE. The absence of Cretaceous formations to the SW of the Pre‐Atlas zone may be mainly attributed to the presence of salt domes.The study of paleotectonic events on the Epihercynian and African platforms, the wide distribution of spilites in the lowermost series of Triassic detritals and the discovery of flysch facies in the Tellian Atlas may support the existence of two interplates, the Saharan and Atlassic plates. However, detailed geological and geophysical studies would be necessary to confirm this

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00264.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The Chanco embayment lies 300 km SSW of Santiago, Chile. The sequence within this basin above the metamorphic basement is: Chanco Formation (very clean sandstone), Quiriquina Formation (glauconitic sancistone, rich in organic matter), and Navidad Group (a very good caprock). This section thus contains reservoir, source and caprocks, and is therefore very promising for petroleum investigations. The offshore C‐1 well yielded salt‐water with gas shows, andtwo wells drilled onshore yielded flows of gas. The C‐1 well lies on a gently‐dipping EW‐striking anticlinal structure, the presence of which makes the area very pr

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00265.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The paleogeography postulated from the distribution of Permian and Triassic sedimentary rocks in the Middle East is shown and related to the paleostructure of the region. The Middle East region as defined here includes the Arabian Peninsula, Iran, Iraq, SE Turkey, Syria, Lebanon, Jordan, West Jordan, and the Sinai Peninsula. Within the limits of the area included in this study, a relatively stable pre‐Late Triassic tectonic regime can be recognized and distinguished from a succession of diastrophic events of the Late Triassic epoch, which caused marked changes in the types and distribution of facies.Excluding NE Iran, the Middle East was stable from Late Cambrian to Middle Triassic times, as it formed a part of the Arabian Massif and much of the Middle East Platform, which is a broad shelf bordering the positive Afro‐Arabian Massif to the NE and east. The sediments of this plarform have undergone no strong deformation and have been subjected only to epeirogenic movements which interrupted sedimentation locally or regionally. However, from Upper Permian through Middle Triassic times, the predominant facies on this shelf was carbonates which unconformably overlie the non‐marine or extremely shallow marine elastics of the Lower Permian or older strata in most of the region.Upper Triassic strata in the area are markedly different in facies from older beds because of the movement of blocks in Turkey and northern and eastern Iraq and Iran related to the enlargement and broadening of the Tethys. Asa result, much of northern and eastern Iran were separated from the area to the south and west, which continued to be a shelf flanking the Afro‐Arabian Massif. Consequently, three major structural elements existed in the region: the Arabian Shelf, the Tethyan rift zone and the Paleo‐Tethy

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00266.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00267.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Book reviewed in this article:“The Geology of Offshore Ireland and West Britain” by D. Naylor and P. M. Shannon.“Geophysics in the Affairs of Man” by C. C. Bates, T. F. Gaskell and R. B. Rice.“The Cambridge Encyclopedia of Earth Sciences”, edited by D. G. Smith.“Continental and Oceanic Rifts” edited by G. Palmason.“Developments in Geophysical Exploration Methods – 4”, edited by A. A. Fitch.“Banco de Piedras”, by A. R. Martinez.“Continental Carbonate Sedimentation and Pedogenesis—Late Cretaceous and Early Tertiary of Southern France” by P. Freyett and B. H. Purser.“World Energy Supply”; by Manfred Grathwohl translated by M. Brewer.“Computer applications in Geology III”, Geological Society Miscellaneous Paper No. 15.“A Geological Time Scale” by W. B. Harlandet al.“Petroleum Geology for

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00268.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00269.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY