ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00904.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Detailed subsurface studies of the northern part of the Suez Rift and adjacent areas indicate the superposition of two different episodes of deformation. During the earlier (Late Cretaceous) phase of deformation, folds with NE‐SW oriented axes were formed in northern Egypt as a result of convergence between Africa and Eurasia and the closure of the Neotethys. During the later (early Miocene) deformation., NW‐oriented normal faults were formed as a result of the opening of the Suez Rift.Borehole data have shown that a belt of NE en échelon folds with NE‐SW axes exists in the subsurface in the northernmost part of the rift, between Ayun Musa and the Sukhna‐1 well, soulth of Geble Ataqa. This fold belt represents the SW continuation of the en échelon folds exposed in the Mitla Pass, to the NE of the rift. Another pre‐rift structure is the offshore extension of the Wadi Araba structure as a SE‐facing monocline. This offshore structure also represents the continuation of the Geble Somar structure, on the eastern shoulder of the Suez Rift. The Geble Somar and Wadi Araba Structures represent the southernmost prerift folds in northern Egypt. Pre‐rift folds in the study area stood high above sea‐level during the Palaeocene and early Eocene. Upper Cretaceous and/or older rocks in the cores of these folds were later unconformably covered by middle Eocene rocks. The presence of Late Cretaceous folds should be taken into consideration when exploring for hydrocarbons in this part of the Suez Rift.Borehole data in NE Egypt also indicate the presence of Late Cretaceous folds underneath the almost flat‐laying Tertiary rocks in the northern part of the Eastern Desert. These folds are condidered to be potential hydrocarbon traps in this relatively p

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00905.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Subduction of the Tethys oceanic plate beneath the Lesser Caucasus island are in the Late Creataceous — Eocene produced conditions favourable for the generation and accumulation of hydrocarbons. Subduction of crust in the Transcaucasus Massif led to the formation of various types of trap. Also, geothermal gradients here were high, resulting in the generation of hydrocarbons in shallow‐water sediments on the margins of the Massif, and their accumulation in both sedimentary and volcaniclastic reservoirs (e.g. in the Samgori‐Patardzeuli and Muradkhanly fields).The geodynamic setting of the NW margins of the Pacific Ocean was similar in the Neogene to that of the Transcaucasus Massif. Oceanic crust was subducted during the Oligo‐Miocene, and a series of inter‐are rifts were formed. The principal oilfields of Japan, where accumulations are resrvoired in volcaniclastic strata (Neogene‐Pleistocene) are located here. A possible analogue is the rift located in the southern East Kuril Basin, where the occurrence of petroleum has been inferred. Lithological studies of the Komandorsky Islands, eastern Kamchatka, the Kuril Islands and western Sakhalin indicate that the distribution of the reservoirs depends on the stage of evolution of the rifts and adjacent

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00906.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Solid bitumens from the Seridhalivein, occurring in the Upper Cretaceous—Palaeocene Germav Formation, and five oils from different oilfields in SE Turkey, were investigated by a variety of organic geochemical methods. Based on biomarker distributions (pristane/phytane, carbon number preference (CPI), Norhopane/hopane, extended hopane distribution, pregnanes/regular steranes), a marine carbonate depositional environment is inferred for the source of these oils. The oils are “early mature‘, as indicated by their ethylcholestane 20S/20S + 20R ratios, and the 17α(H), 21β(H)‐bishomohopane 22S/22S + 22R ratios. Differences in relative abundance of some compounds typical of higher salinities in the depositional environment (docosane, pregnane) suggest different sources of facies variations within a common source. No aromatic sulfur compounds were detected in the oils.The solid bitumens were characterized by a high abundance of dibenzothiophenes, naphthalenes, phenanthrenes and their alkyl‐substituted homologues in the aromatic fractions, and an abundance of n‐alkanes in the saturate fraction. The high maturity of the solid bitumen (epi‐impsonite, R %equiv. ? 1.2) makes an interpretation on the origin of these substances difficult. An origin due to biodegradation of sulfur‐rich oil is excluded, since the alkane and aromatic fractions do not show signs of a severe microbial degradation. The absence of sulfur compounds in the oil extracts and the pyrolysis products of the asphaltene fraction show genetic differences between the oils and solid bitumens of SE Turkey. Pyrolysis of the asphaltenes from the bitumen extracts and of the unextracted bitumens produced sulfur compounds similar to those found in the

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00907.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The hard, resistant, generally cliff‐forming Pab Sandstone Formation of Maastrichtian age is well exposed in parts of the eastern Sulaiman Fold‐Belt. Thin‐section, XRD and SEM studies of 66 samples from seven outcrops extending 200 km along strike were made in order to assess the reservoir quality of this formation. Petrographic studies indicated that the sandstones, classified as quartz arenites (locally subarkose), are texturally and mineralogically mature. The proportion of potassium feldspar varied from trace to 16%, and this mineral was confined to certain stratigraphic zones. Alteration of feldspars to clay minerals was common, particularly in the south of the study area. Plagioclase, heavy minerals, and lithic fragments were present in minor amounts.Diagenetic kaolinite, illite and chlorite were common, with kaolinite being the most abundant. Quartz overgrowths constitute the dominant cement. The reservoir quality of the formation largely depends on the composition of the sandstone, and its susceptibility to chemical alteration. Most of the porosity (up to 16%) results from the dissolution of feldspar grains; dissolution was restricted to the south of the study area, and the feldspars in the north show little alteration and no dissolution.Reservoir potential has also been influenced by the substantial input of silica‐rich solutions that completely destroyed the primary porosity of the sandstone. The observed porosity is mostly secondary, commonly formed by dissolution of feldspar grains, and occasionally cement/matrix.The sequence of diagenetic events is, from oldest to youngest: formation of pyrite; formation of early‐stage calcite; formation of dolomite; silica cementation; formation of clays; precipitation of late‐stage calcite; feldspar dissolution; and formation of iron oxides. The textural and mineralogical maturity, coupled with local well‐developed secondary porosity, may make the Pab Sandstone Formation a good r

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00908.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Seismic modelling has been applied to define the porous carbonate intervals and lithologic boundaries resolved in the seismic section at the Løgumkloster‐ 1 Well, southern Jylland, Denmark, This well encountered a 14‐m thick, porous Zechstein carbonate interval (Ca‐2) with an oil show, but the well was plugged and abandoned.Band‐pass filtering and blocking of the acoustic‐impedance log in the time domain have been used to define a number of successive acoustic‐impedance models. The simplest of these, from which a synthetic seismogram correlates with the synthetic seismogram derived from the original acoustic‐impedance log, is assumed to define the maximum number of intervals resolved in the seismic section at the well location. As the well data was acquired in an area represented by a variable seismic reflection pattern, a new optimal seismic section CMP location was found, to optimise the correlation between the synthetic seismogram and the seismic section.Fifteen acoustic‐impedance intervals could be resolved in the seismic section at the Løgumkloster‐1 Well location, including the porous Ca‐2 carbonate interval. A close relationship was found between the Ca‐lb, Ca‐2 and Ca‐3 carbonate layers and lateral variations in the seismic reflection pattern, which indicates sign

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00909.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

The complex structure of sedimentary basins on the continental shelf of southern Vietnam, and the existence of various kinds of oil and gas traps, has been studied by seismic stratigraphy. Seismic stratigraphy has been used to investigate the sedimentary evolution of these basins: seismic sequences have been delineated, and potential oil and gas traps have been located.

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00910.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00911.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

Book reviewed in this article:“The Petroleum System from source to trap: AAPG Memoir 60”, edited by L. B. Magoon and W. G. Dow.“Evolution of the Tasman Sea Basin”, edited by G. J. van der Lingen et al.Geofluids: Origin, Migration and Evolution of Fluids in Sedimentary Basins. edited by J. Parnell.“Sedimentary organic matter: organic facies and palynofacies”. by

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1995.tb00912.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY