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Assessment of fluid contacts and compartmentalization in sandstone reservoirs using fluid inclusions; an example from the Magnus oil field, North Sea

S. A. Barclay, R. H. Worden, J. Parnell, D. L. Hall and S. M. Sterner
Assessment of fluid contacts and compartmentalization in sandstone reservoirs using fluid inclusions; an example from the Magnus oil field, North Sea
AAPG Bulletin (April 2000) 84 (4): 489-504

Abstract

Location of an oil-water contact is crucial for estimating reserves and for designing production strategies. Identifying hydrodynamic barriers or baffles is also important for optimizing both recovery and flow rates. In some oil fields, identifying fluid contacts and barriers is not always possible using conventional wireline and formation testing methods. We have used a novel technique, fluid inclusion stratigraphy (FIS), to tackle these problems in the Upper Jurassic Magnus oil field in the North Sea. This technique involves systematic cleaning and crushing of small quantities of a large number of drill-cuttings or core samples followed by mass spectrometry without prior GC (gas chromatography) separation. The quantity and specific types of petroleum fluid trapped in pores in mineral grains are determined and the stratigraphic and spatial pattern of organic compounds constructed. For this case study, these data were integrated with quantitative mineralogical data derived from gamma-ray, density, sonic, and neutron porosity logs, together with electrical resistivity. The conventional resistivity data resulted in ambiguity concerning the oil-water transition zone in both wells; interpreting the resistivity logs was locally hampered by vertical changes in reservoir lithology. The FIS data suggested more complex transition zones (locally variable water saturations in the transition zone controlled by shales and dolomites) and petroleum extending deeper than suggested by the resistivity log (possibly due to lack of sensitivity of the latter to low petroleum saturations in water-wet reservoirs). The FIS data also suggested the presence of potential stratigraphic (shale) and diagenetic (dolomite) barriers or baffles to fluid flow within the reservoir, illustrated by changes in abundance and composition of petroleum-bearing inclusions.


ISSN: 0149-1423
EISSN: 1558-9153
Coden: AABUD2
Serial Title: AAPG Bulletin
Serial Volume: 84
Serial Issue: 4
Title: Assessment of fluid contacts and compartmentalization in sandstone reservoirs using fluid inclusions; an example from the Magnus oil field, North Sea
Affiliation: Queen's University, School of Geosciences, Belfast, United Kingdom
Pages: 489-504
Published: 200004
Text Language: English
Publisher: American Association of Petroleum Geologists, Tulsa, OK, United States
References: 26
Accession Number: 2000-034553
Categories: Economic geology, geology of energy sources
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. 2 tables, sect., sketch map
N51°00'00" - N61°10'00", W04°00'00" - E11°00'00"
Secondary Affiliation: 3Fluid Inclusion Technologies, USA, United StatesUniversity of Aberdeen, Department of Geology and Petroleum Geology, GBR, United Kingdom
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by American Association of Petroleum Geologists, Tulsa, OK, United States
Update Code: 200011
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