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Possible occurrences of transition zones and residual oil zones below oil-water contacts in mature oil fields, southeast Saskatchewan

Chengyu Yang and Hairuo Qing
Possible occurrences of transition zones and residual oil zones below oil-water contacts in mature oil fields, southeast Saskatchewan
Interpretation (Tulsa) (November 2016) 4 (4): T591-T612

Abstract

A transition zone (TZ) from oil to water formed by capillary force beneath traditionally defined producing oil-water contact (OWC) has been well-known for years. Recent research and production activities in the Permian Basin and the Williston Basin in United States suggests that a residual oil zone (ROZ) may exist below traditionally defined OWC under certain geologic and hydrodynamic conditions. If this ROZ is sufficiently thick and extensive, it may be economically recoverable using tertiary recovery techniques. We have investigated possible occurrences of TZ/ROZ in the Williston Basin, southeast Saskatchewan, using well-log interpretation based on Archie's equation. Out of 33 pools examined, we have evaluated three areas, the Bellegarde Tilston pool area, an unnamed Souris Valley pool, and the Rosebank Alida pool area, as possibly having thick (up to 47 m) low-oil-saturation TZ/ROZs below the OWCs. Evidence includes oil stains, core-based oil saturation, fluorescence on drill cuttings, and oil shows and sulfur water reported in drill stem tests. The oil in place within the possible TZ/ROZs is estimated to be approximately half the amount of the oil within their associated main pay zones. Tilted OWC and other findings may suggest that the identified oil-bearing zones are ROZs related to hydrodynamics. The hydrodynamic flows may also have created some other ROZs that still remain undiscovered.


ISSN: 2324-8858
EISSN: 2324-8866
Serial Title: Interpretation (Tulsa)
Serial Volume: 4
Serial Issue: 4
Title: Possible occurrences of transition zones and residual oil zones below oil-water contacts in mature oil fields, southeast Saskatchewan
Affiliation: University of Regina, Regina, SK, Canada
Pages: T591-T612
Published: 201611
Text Language: English
Publisher: Society of Exploration Geophysicists, Tulsa, OK, United States
References: 45
Accession Number: 2017-004719
Categories: Economic geology, geology of energy sources
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., 3 tables, sketch maps
N49°00'00" - N60°00'00", W110°00'00" - W101°19'60"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by Society of Exploration Geophysicists, Tulsa, OK, United States
Update Code: 201704
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