ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1991.tb00304.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1991.tb00305.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1991.tb00306.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Book reviewed in this article:Lacustrine petroleum source rocks “Lacustrine petroleum source rocks”, edited by A. J. Fleet, K. Kelts and M. R. Tulbot.Regional studies The Andes “Geology of the Andes and its relation to hydrocarbon and mineral resources”, edited by G. E. Ericksen, M. T. Canas Pinochet and J. A. Reinemund.Regional studies North Greenland “Petroleum Geology of North Greenland”. Bull. Gronlands Geol. Unders. 158, edited by E G. C

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1991.tb00307.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1991.tb00308.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1991.tb00357.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Rayleigh‐Taylor instabilities occur when low‐density layers of viscous fluids are overlain by denser layers. Gravity overturn of such instabilities leads to the rise of the unstable light (source) fluid as diapirs (e.g. of salt) through the denser (overburden) layers (e.g. of clastic sediments). Lnteral extension or movements of faults in the bottom boundary at any stage during such gravity overturns are expected to have a great effect on the geometry, growth rate and location of onv salt structures.Two groups of material models, each consisting of three series, were used to study the effect of uniform extension. and the non‐uniform extension due to reactivation of pre‐existing basement faults. on gravity‐driven overturns at different stages. The overburden in a third group model consisted of a stiffer non‐Newtonian fluid. All the models were loose&scaled to an early stage of the North Sea. All the diapirs were upbuilt, because all the overburden was in place from the start.Pre‐extension/prefaulting model diapirs are essentially vertical, symmetrical and finger‐like with circular planforms and with isotropic lateral spacings predictable by Ramberg theory. When reactivated and deformed by Inter extension. these diapirs become inclined in profile, and develop elliptical planforms elongate in the direction of extension. Diapirs which rise in an tnstable sequence already thinned uniformly are only smaller, closer and slower.Post faulting model diapirs (in group 2 models) rise as asymmetric walls or rows of fingers, some above the, fault‐scarps in the basement. others above the fault blocks.Synextension model diapirs rise from a thinning source layer; some are inclined and osymmetric in profile; some hove circular planforms, while others are elliptical and elongate in the extension direction. Synfaulting diapirs which form during reactivation of extensional basement, faults. develop as inclined and asymmetric walls overhanging the fault scarps. Finger‐like diapirs separated from synfaulting walls occur in rows parallel to the faults, and have elliptical planforms elongate in the extension direction or. if located in local regimes of shallow compression, perpendicular to it,When the overburden was non‐Newtonian with a power law component n=8.1. diapirs of the source surfaced only along extensional faults in the overburden.The model results are used to comment on recent interpretations of how halokinesis and extension intera

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1991.tb00358.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Carboniferous sandstones occur in several basins in the north of Ireland, deposited predominantly in fluvio‐deltaic environments. The Carboniferous is thickest in the west of the region. Primary compositional variations are evident: in particular. the sandstones are more arkosic in the west. Variations in authigenic mineralogy also occur: sandstones in the west contain greater volumes of ciuthigenic quartz, and exhibit hairy/fibrous illite which is lacking in the east. The distribution of carbonate and sulphate cements is more irregular. and is related to the distribution of marine limestone and evaporite beds. Porosity in the sandstones is secondary after dissolution of carbonate and sulphate cements and. to a lesser degree, dissolution of unstable grains. Porosities are generally low (less than 5%) in the west, but sandstones there may he comparable with those in tight gas reservoirs elsewhere. Sandstones in the east exhibit very high porosities in boreholes. Kaolinite is a late phase occupying pore space in the upper parts of most successions. deposited by downward‐migrating meteoric fluids. possibly during Permian times. Late iron oxides in some sandstones were similarly precipitated during deep weathering below the sub‐Permian unconformity Sandstones exhibit very patchy bitumen residues in the west. demonstrating that oil has migrated through these

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1991.tb00359.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

The movement of fluids up growth faults is proposed to be periodic; when faults are active they can concentrate fluid flow, but when inactive, flow is restricted. Higher flow rates are predicted to be caused by fault‐zone permeabilities and fluid potentials increasing at shear stresses close to the shear strength of the rock. In this way, significant flow is confined to the most active sections of moving faults. Since fault activity is related to sediment accumulation rates, the volume of fluid flowing up faults should be greatest when accumulation rates are high.Periodic flow explains the evidence which indicates that faults can be both barriers and avenues of fluid migration. Evidence for growth faults being avenues of fluid migration is shown by fault‐zone mineralization. lowered fluid potentials. thermal anomalies, salinity anomalies. and isotope studies. In contrast, fault‐zone porosity studies. measured flow rates, high juxtaposed fluid potential differences, differential subsidence caused by groundwater production, and hydrocarbon accumulations, all suggest that growth fault zones are of low permeability.The flow of‐oil from large pore spaces into smaller, water‐filled pore spaces requires a large potential gradient. Therefore., faults which cut water‐wet sections with variable vertical permeability are usually poor conduits for oil. In contrast, in hydrocarbon‐saturated homogeneous rocks, such as mature shales. the vertical flow of migrating hydrocarbons may be concentrated by faults. The degree of concentration will depend on the permeability of t

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1991.tb00360.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

A modelling study aimed at providing a better understanding of the hydrocarbon accumulations on the SW flank of the Dead Sea graben in Israel has been performed. It considers the recent geochemical finding that the source rock of the hydrocarbon occurrences in the area is the Senonian bituminous chalk and marl, buried in the central Dead Sea graben. The study investigates the effect of the regional geological and hydrogeological conditions, associated with the physical properries of the rock and fluids, on the migration and types of hydrocarbon accumulations. The investigation was performed by means of a three‐phase, two‐dimensional, numerical reservoir simulator. Typical cross‐sections, through potential anticlinal hydrocarbon traps, were considered. The study analyses possible hydrodynamic flushing in the water‐flow direction, as well as counter‐current migration in a direction opposite to the potentiometric water gradients, from the Dead Sea graben upwards.In addition to conventional hydrodynamic traps. the study includes the case of downdip entrapment due to low permeability regions. It is concluded that: (i)from the hydrodynamic point of view, the easiest oil migration path is through Paleozoic — Triassic formations: (ii) the high water salinity of these beds facilitates the up‐structure oil flow in a direction opposite to the water current movement: (iii) the Jurassic beds are probably impregnated by oil and gas coming from Triassic strata through faults: (iv) undiscovered structural traps are likely to contain mostly gas; and (v) down‐faulted blocks adjacent to sealing faults. or to low‐permeable regions (including permeable faults), are po

ISSN:0141-6421    

DOI:10.1111/j.1747-5457.1991.tb00361.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY