Reservoir quality in relation to facies, burial history, and oil migration: A review
- Petroscan I.P. Consultants, Calgary, Alberta (Canada)
The diagenetic make-up and, in consequence, the ultimate reservoir quality of a sand body depends on depositional facies, as well as on burial history, diagenetic fluid chemistry and timing of oil migration. A regional subsurface study in the Maracaibo Basin, Venezuela along a northwest-southeast transect in the Urdaneta, Lagunillas and Barua-Motatan fields reveal that depositional facies of the reservoir sandstones range from mainly fluvial (Urdaneta) to deltaic-coastal marine in Lagunillas, and typically sublittoral in the Barua-Motatan area. Factors such as granulometry, development of early pore-lining chlorite (in marginal marine facies), infiltrated grain-coating clays (fluvial B-6 sands), and proximity of reservoirs to the post-Eocene unconformity, have preserved, enhanced or otherwise influenced reservoir quality. Data on authigenic mineralogy, vitrinite reflectance and burial history indicate a progressively greater subsidence from northwest to southeast. As a result, diagenetic grade is immature in Urdaneta where porosity/permeability values are the highest. In contrast, the Barua-Motatan field in the southeast is typified by a higher grade of diagenesis, varied authigenic mineralogy, and severe deterioration of reservoir quality. Similarly, degree of compaction progressively increases from northwest to southeast. Timing of oil migration have parallelly contributed to systematic regional variation in reservoir quality. An early migration in Urdaneta has been favorable to preservation of original porosity. In contrast, late migration during Upper Miocene, in the Barua-Motatan field, indirectly permitted abundant silicification and consequent destruction of virtually all primary porosity. Thus both pre- and post-depositional parameters are important constraints which should be considered while evaluating quality of siliciclastic reservoirs.
- OSTI ID:
- 5941927
- Report Number(s):
- CONF-930306--
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 77:2; ISSN 0149-1423; ISSN AABUD2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
CLAYS
CONSTRAINTS
DEVELOPING COUNTRIES
DIAGENESIS
DOCUMENT TYPES
GEOLOGIC DEPOSITS
HYDROCARBONS
LATIN AMERICA
MACERALS
MIGRATION
MINERAL RESOURCES
MINERALOGY
ORGANIC COMPOUNDS
PERMEABILITY
PETROLEUM DEPOSITS
POROSITY
PRODUCTIVITY
RESERVOIR ROCK
RESOURCES
REVIEWS
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SOUTH AMERICA
VENEZUELA
VITRINITE