Organic facies and systems tracts: Implications for source rock preservation and prediction
- Univ. of Utrecht (Netherlands)
Sequence stratigraphy is concerned with making predictions about reservoirs ahead of the drill, however, little attention has been paid to the configuration of organic-rich facies of source rock quality. We suggest that preservation of source rock type facies in clastic systems is mutually exclusive and time successive. The main database is a collection of cores and other samples through the Holocene Rhone delta. The early Holocene Transgressive Systems Tract (TST) contains five levels of channelization. The most significant peat bed is located immediately landward of the shoreline of maximum transgression (SMT). The Highstand Systems Tract (HST) consists of two parasequences, containing mostly laterally continuous strandplain complexes without peat. In addition to sufficient accommodation space, an important control on formation of fresh-water peats and organic-rich shelf muds is availability of river-induced nutrients. Peat quality, however, is best without riverine clastics. In a delta plain, a balance between these two controls may be reached when river-fed nutrients are trapped there indirectly. The potential for such a condition arises in a TST setting. On the shelf, eutrophication of marine habitats is also controlled by river-fed nutrients, but excess river clastics are detrimental to marine source rock quality. A balance between these two controls may be reached in HST settings where fine-grained riverine clastics are forced onto the shelf rather than in the delta plain. In this case, nutrient supply to the shelf results in large quantities of marine biomass. This biomass becomes sufficiently concentrated due to moderate fine-grained riverine sedimentation which guarantees burial and preservation. Thus, varying river-water and nutrient supply in TST and HST settings seems to control large-scale preservation patterns of both continental and marine organics. This hypothesis suggests further potential for using sequence stratigraphy for source rock occurrence.
- OSTI ID:
- 6916405
- Report Number(s):
- CONF-9310237-; CODEN: AABUD2
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Vol. 77:9; Conference: American Association of Petroleum Geologists (AAPG) mid-continent section meeting, Amarillo, TX (United States), 10-12 Oct 1993; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
03 NATURAL GAS
EUTROPHICATION
CONTROL
ORGANIC MATTER
PRESERVATION
SEDIMENTATION
SOURCE ROCKS
DEPOSITION
FORECASTING
FRESH WATER
HYPOTHESIS
NUTRIENTS
PEAT
RESERVOIR ROCK
RIVER DELTAS
SEAWATER
STRATIGRAPHY
COASTAL REGIONS
ENERGY SOURCES
FOSSIL FUELS
FUELS
GEOLOGY
HYDROGEN COMPOUNDS
MATTER
OXYGEN COMPOUNDS
WATER
020200* - Petroleum- Reserves
Geology
& Exploration
030200 - Natural Gas- Reserves
Geology
& Exploration