ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00410.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.tb00411.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The general concept of petroleum formation by biogenic mechanisms has been firmly entrenched for a long time, but there has been no accumulation of convincing experimental evidence in support of this belief. If, on the other hand, a juvenile origin is considered, rigorous mathematical and experimental treatments are possible. This is done here. The mathematical foundation of the juvenile petroleum model is drawn from the model that has quantitatively explained the formation of the atmosphere, the oceans, and surficial carbonaceous matter by outgassing of the Earth. Experimental data for the abundance of juvenile precursors of petroleum — H2, CO, alcohols and hydrocarbons — are obtained from diamond carriers which crystallized in the upper mantle 3.1 billion years ago. The correlation that exists world‐wide between the distribution of petroleum accumulations and regions that have experienced diastrophism is interpreted as demonstrating a direct relationship between plate tectonics and channels of precursor outflow from the upper mantle to crustal traps. The conversion of precursors to petroleum is assigned to maturation processes. The theoretical coefficient of juvenile petroleum production is compared with coefficients of petroleum accumulation derived from published data on 78 giant petroleum accumulations. Agreement is found in all cases. The various “proofs” of a biological origin for petroleum are examined and found to be inconclusive. It is concluded that recognition of a mainly juvenile origin has been clouded by traces of biologically‐derived compounds and fossils that are merely intrinsic to the sedimentary nature of “source rock” and reservoirs. Limitations of the juvenile petroleum model and its possible value for petroleum exploratio

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00412.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Maps of pressure measurements and fluid distribution are important tools in deciphering the geology of complex reservoirs. To understand the original entrapment and present‐day distribution of hydrocarbons in the Salina Pool of Portachuelo Field, NW Peru, we used pressure and production data, in conjunction with a detailed analysis of how the pool is put together structurally and stratigraphically. In Portachuelo up to 45 Lower Eocene (Salina) sands, which can be oil‐, gas‐, or water‐bearing in different wells, have been offset by a veritable maze of normal faults. To reconstruct this jig‐saw puzzle we used “composite” electric logs that provided a close approximation of the Salina sequence prior to faulting.The Salina Pool of Portachuelo offers a challenging place to hunt for commercial oil in a 490‐m sequence of multiple thin (2–10 m) sands within small fault‐blocks. In this search it is helpful to consider the pool as a fluid system in which the reservoir geometry, defined by both stratigraphy and structure, is only one major element; the other two elements are the fluid content of the system and its internal energy, as reflected in the reservoir pressure.Because of the remarkable complexity of the reservoir geometry, it was the present‐day distribution of fluids and pressures that eventually provided the key to the pool's history of entrapment. Only after fluid and pressure variations were interpreted in terms of the structural evolution did it become clear that Portachuelo's oil originally accumulated in a well‐defined anticline. This simple distribution was destroyed by faulting, which thinned and collapsed the anticlinal crest while raising the flanks. Gas, because of its higher mobility, was more widely redistri

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00413.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Formational water characterization denotes a chloride‐calcium type in the S1S2A2class. It indicates a hydrodynamic zone unfavourable for hydrocarbon preservation in the eastern block of the field. These waters have an index of base exchange (IBE) greater than 0.129, indicating connate oil reservoir waters, migrating with oil from the oil source‐beds at the southern parts of the field through connected openings and fault planes.The entrapment of oil took place at the crestal parts of the folded structure to the west and NW of the field. The water moved down‐dip along the eastern flank, creating capillary pressure, forcing the oil to accumulate in subcapillary pores at the top‐most parts of the upper pay‐zone. The latter section became oil‐wet. The oil wettability led to entrapment of a quantity of oil in the subcapillary pores that was then left behind during oil production operations, necessitating secondary recovery methods.The occurrence of more lighter constituents in crudes of the upper pay‐zone than in the lower one is due to fractionation and differentiation dur

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00414.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Mineral‐free kerogen concentrates have been fractionated into their components by the use of differential and sequential gravity separation methods. The density of each component within a kerogen depends upon its chemical composition which is a function of the original organic matter and its level of organic maturation.The mineral‐free kerogen concentrates were analysed for the elements carbon, hydrogen and oxygen and these results, combined with visual kerogen examination, allowed estimations of kerogen type and degree of maturation to be made.The separation procedure also allows the composition of the sedimentary organic matter to be assessed and thus, with the knowledge of the level of maturity and the possible convertibility of each component into fluid hydrocarbons, a more accurate assessment of the hydrocarbon potential of the kerogen can be obtained.The quantity of unproductive carbon can be identified by density separation, and the different types of amorphous kerogen can also be identified and separated by means of this method. The oil‐prone amorphous kerogens have lower specific gravities than the amorphous gas‐prone m

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00415.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A study of the surface and subsurface geology of the Zagros mountain belt reveals that, from the viewpoint of tectonic fabrics and the cause of diastrophism, the Zagros geosyncline can be divided into NW and SE segments. The NW segment was formed by orogenic compression and the SE segment primarily by epeirogenic uplifts. Movements of Infra‐Cambrian (Hormuz) salt at the base of the sedimentary column in the SE Zagros contributed to the epeirogenesis. Faults in the SE Zagros are of a normal type, whereas in the NW Zagros they are dominantly thrust. Seismic data indicate that movement of salt is the cause of many of the earthquake shocks in the SE Zagros.Hydrocarbons in the SSE Zagros either escaped through fractures within exposed reservoirs or migrated while epeirogeny was proceeding to be trapped in the western flank of the Oman high in the extreme SE portion of the Zagros bel

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00416.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The concentration, type and thermal maturity of organic matter from the Imo Shale, Nkporo Shale and the upper parts of the Nkalagu Formation which were penetrated by the Akukwa‐2 well are presented. The organic carbon content ranged from 0.4–3.5%. The kerogens from the various formations were of the humic and mixed varieties. Evidence from independent thermal maturity parameters (namely, average vitrinite reflectance (R0%), Tmaxand transformation ratio from Rock‐Eval, n‐alkanes distribution pattern, and hopane “fingerprint”) combined to locate the top of the ‘oil window’ within the Nkporo Shale at a depth of approximately 2,000 m from the surface. This corresponds to a threshold temperature ofcirca 65°C.Sedimentary organic matter which is favourable for both gas and oil generation is therefore probably abundant in the Anambra basin. Hydrocarbon reservoirs are possibly located at relatively shallow depths where accumulations of heavy oils may

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00417.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The results reported here are from a series of simple experiments designed to test the hypothesis that algal material associated with modern carbonate ooids is capable of regeneration after prolonged periods of desiccation. Although they do not provide any positive proof of this, they do show evidence for the generation of methane gas associated with ooids, as well as possible evidence for the consumption of methane by sulphate reducing bacteria. The implication is that the ooids themselves provide a suitable anaerobic environment in which methanogenic bacteria can live. These results are in line with the conclusions of Ferguson and Ibe (1981), that there is some process acting within the individual ooids which allows the formation of hydrocarbons in an otherwise aerobic marine environment.

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00418.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Book reviewed in this article:“An Introduction to the Physics and Chemistry of Petroleum”, by R. R. F. Kinghorn.“Quantitative Stratigraphic Correlation”, edited by J. M. Cubitt and R. A. Reyment.“Arctic Geology and Geophysics”, edited by A. F. Embry and H. R. Balkwill.Mountain Building Processes“, Ed. K. J. Hsii.“European Energy Prospects to the year 1990” by George Ray and Colin Robinson.“Petroleum geology of the SE North Sea and the adjacent onshore areas”, Proceedings of a Conference held in the Hague in November 1982 by the Royal Geological and Mining Society of the Netherlands; edited by J. P. H. Kraasschieter and T. J. A. Reijers.“The Variscan fold belt in the British Isles”, edited by P. L. Hancock.“Energy for our World—Energy, Society, Environment”, Digest of the World Energ

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1983.tb00419.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY