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Titolo:
THE RELATIONSHIP BETWEEN PETROLEUM EMPLACEMENT AND CARBONATE RESERVOIR QUALITY - EXAMPLES FROM ABU-DHABI AND THE AMU DARYA BASIN
Autore:
NEILSON JE; OXTOBY NH; SIMMONS MD; SIMPSON IR; FORTUNATOVA NK;
Indirizzi:
CARBONATE RESERVOIRS LTD,11 CAIRN CRESCENT ABERDEEN AB15 9TW SCOTLAND BP RES SUNBURY TW16 7LN MIDDX ENGLAND BP EXPLORAT & PROD UXBRIDGE UB8 1PD MIDDX ENGLAND VNIGNI MOSCOW 105819 RUSSIA
Titolo Testata:
Marine and petroleum geology
fascicolo: 1, volume: 15, anno: 1998,
pagine: 57 - 72
SICI:
0264-8172(1998)15:1<57:TRBPEA>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
FLUID INCLUSIONS; CALCIUM-CARBONATE; SOUTHERN ENGLAND; MIDDLE-EAST; CEMENTS; MICROPOROSITY; DIAGENESIS; MIGRATION; LIMESTONE; MINERALS;
Keywords:
CARBONATES; RESERVOIR QUALITY; DIAGENESIS; PETROLEUM; ABU DHABI; AMU DARYA; THAMAMA GROUP;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
42
Recensione:
Indirizzi per estratti:
Citazione:
J.E. Neilson et al., "THE RELATIONSHIP BETWEEN PETROLEUM EMPLACEMENT AND CARBONATE RESERVOIR QUALITY - EXAMPLES FROM ABU-DHABI AND THE AMU DARYA BASIN", Marine and petroleum geology, 15(1), 1998, pp. 57-72

Abstract

The relative importance of petroleum emplacement in inhibiting diagenetic processes and preserving porosity and permeability in Lower Cretaceous, Thamama Group (Kharaib Formation) carbonate reservoirs of Abu Dhabi, UAE, and in Callovian-Kimmeridgian carbonate reservoirs of the Amu Darya Basin in Uzbekistan and Turkmenistan, has been evaluated by combining geologic, petrophysical and geochemical data. When petroleum emplacement is synchronous with and prior to significant burial cementation in carbonates, primary petroleum inclusions are trapped in the cements. The process appears to be characrerised by steep intra-field porosity-depth trends within a more gradual regional decline in porosity with depth. This has profound implications for the prediction of porosity in carbonate reservoirs. Reservoir quality is better in grainstones and packstones compared to adjacent wackestones and lime mudstonesin the Kharaib Formation because of preserved macroporosity (intergranular, vuggy, mouldic); the pore system in the finer units is dominated by micropores. These features indicate a primary textural control onporosity and permeability. Within the grainstones and packstones, macroporosity is variably filled by late equant sparry calcite cements. Porosity and permeability variations in grainstones and packstones at areservoir scale are therefore controlled by the variation in amount of equant sparry calcite cement. This in turn depends on the timing of the precipitation of this cement relative to petroleum emplacement, asshown by fluid inclusion data. Where petroleum emplacement has occurred relatively early, at migration foci, prior to significant burial cementation by equant sparry calcite, reservoir duality is preserved. Where it has occurred after significant burial cementation, reservoir quality has been destroyed. In the Amu Darya sequences, primary macroporosity is commonly preserved down to depths of 11,000 ft (3.5 km) with differences in the porosity and permeability characteristics of grainstones being controlled by variations in the amount of early, probably freshwater, cement and the extent of associated dissolution. Small volumes of burial cements do occur, but they do not contain petroleum inclusions. Consequently, there is no firm evidence that petroleum emplacement has inhibited diagenesis in this area. This part of the study has shown that it is not always possible to obtain conclusive evidence from the diagenesis to pin down the processes responsible for the preservation of reservoir quality and that petroleum filling may not alwaysbe the primary cause. The relationships documented here show that the'race for space' between diagenetic waters and petroleum is a major control on reservoir quality in the Thamama Group carbonate reservoirs,but is not so important for the Jurassic carbonates in the Amu Darya basin. (C) 1998 Elsevier Science Ltd. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 01/12/20 alle ore 06:56:48