East Breaks trap formation
| Exploring for Oil and Gas Traps | |
| |
| Series | Treatise in Petroleum Geology |
|---|---|
| Part | Critical elements of the petroleum system |
| Chapter | Sedimentary basin analysis |
| Author | John M. Armentrout |
| Link | Web page |
| Store | AAPG Store |
Minibasin structural-stratigraphic development
The structural/stratigraphic configuration of the East Breaks 160-161 minibasin formed well after Glob alt time. As discussed earlier, the High Island–East Breaks basin was a late Pliocene/early Pleistocene slope basin through which gravity flow sands flowed southward. Progradation overloaded the underlying salt and minibasins formed as a succession of southward-stepping growth-fault/salt-withdrawal sediment thicks (Figure 4-44).
Structural traps
Within these minibasins, structural traps of gravity-flow sandstones formed
- as fault-dependent closure at growth faults,
- as anticlinal closure formed by rollover into growth faults, or
- by postdepositional tilting of sandstones that shale-out upstructure due to syndepositional pinching-out against sea-floor valley margins.[1][2]
Stratigraphic traps
Pure stratigraphic traps occur where basinal sandstones completely bypassed updip areas subsequently filled by mud, providing both top seal and updip lateral seal.[1][3]
Timing of fault movement
Fault movement timing is critical for trap formation timing. Growth-fault rollover anti-clines develop by updip expansion and sediment entrapment on the downthrown side of the fault and consequent downdip sediment starvation and continued subsidence within the intraslope basin (see Figure 4-43 for geometries above the Trim A interval along fault A′). Thus, the updip trap for gravity-flow sandstone is the rollover into the fault, formed during the dynamic phase of fault movement.
Fault A′
In the East Breaks 160-161 minibasin, the fault splay fault A′ forms the northern boundary to the field (Figures 4-42 and 4-43). The dynamic phase of this fault is recorded by the wedge-shaped sediment thickening into the fault, deposited between pre-Hyal B (ca. 1.00 Ma) time and late Trim A (ca. 0.56 Ma) time (Figure 4-31). Its growth phase began about 1.20 Ma.[4][5] Sea-floor expression of this fault clearly indicates offset of Holocene sediments, showing that the fault is currently active (Figure 4-43).
See also
- East breaks petroleum system processes
- Geochemistry of two oils from east breaks
- Hydrocarbon generation model
- Hydrocarbon migration model
- Hydrocarbon accumulation model
- Critical moment (or Interval)
References
- ↑ 1.0 1.1 Bouma, A., H., 1982, Intraslope basins in northwest Gulf of Mexico: a key to ancient submarine canyons and fans: AAPG Memoir 34, p. 567–581.
- ↑ Kneller, B., 1995, Beyond the turbidite paradign: physical models for deposition of turbidites and their implications for reservoir prediction, in Hartley, A., J., Prosser, D., J., eds., Characterization of Deep Marine Clastic Systems: Geological Society, London, Special Publication 94, p. 31–49.
- ↑ Galloway, W., E., McGilvery, T., A., 1995, Facies of a submarine canyon fill reservoir complex, lower Wilcox Group (Paleocene), central Texas coastal plain, in Winn, R., D., Jr., Armentrout, J., M., eds., Turbidites and Associated Deep-Water Facies: WEPM Core Workshop 20, p. 1–23.
- ↑ Armentrout, J., M., Clement, J., F., 1990, Biostratigraphic calibration of depositional cycles: a case study in High Island–Galveston–East Breaks areas, offshore Texas: Proceedings, Gulf Coast Section SEPM 11th Annual Research Conference, p. 21–51.
- ↑ Armentrout, J., M., 1991, Paleontological constraints on depositional modeling: examples of integration of biostratigraphy and seismic stratigraphy, Pliocene–Pleistocene, Gulf of Mexico, in Weimer, P., Link, M., H., eds., Seismic Facies and Sedimentary Processes of Submarine Fans and Turbidite Systems: New York, Springer-Verlag, p. 137–170.
External links
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