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Siliciclastic shorelines and barrier island reservoirs (view source)
Revision as of 21:41, 12 August 2015
, 21:41, 12 August 2015→Shoreface sands form layer-cake geometries
Shoreface sands prograde by lateral accretion with a tendency to produce layer-cake tabular geometries. Depositional dead ends are rare within individual shoreface sandstones, and sweep efficiencies are generally high as a result; for example, Tyler and Ambrose (1986) described excellent continuity and efficient simple sweep in the Carlson shoreface reservoir of the North Markham-North City Bay field of Texas. The large size and excellent lateral continuity of shoreface reservoirs give a reasonable chance that these systems will be in contact with an aquifer (Table 29).
Shoreface sands prograde by lateral accretion with a tendency to produce layer-cake tabular geometries. Depositional dead ends are rare within individual shoreface sandstones, and sweep efficiencies are generally high as a result; for example, Tyler and Ambrose (1986) described excellent continuity and efficient simple sweep in the Carlson shoreface reservoir of the North Markham-North City Bay field of Texas. The large size and excellent lateral continuity of shoreface reservoirs give a reasonable chance that these systems will be in contact with an aquifer (Table 29).
{| class="wikitable"
|-
|+ {{table number|1}}Factors influencing connectivity and reservoir development in siliciclastic shorelines
and barrier island reservoirs.
|-
! Characteristic !! Favorable for Reservoir Development !! Unfavorable for Reservoir Development
|-
| Shoreface sandstones often show layer-cake tabular geometries || Excellent lateral continuity, high sweep efficiency, aquifers common ||
|-
| Shoreface sandstones commonly stack in parasequence sets || || Marine-flooding shales may create poor to no vertical connectivity between individual parasequences
|-
| Shoreface sandstones show upward-increasing permeability profiles || Favorable to high vertical sweep efficiencies ||
|-
| Poor vertical permeability at upper to lower shoreface boundaries (e.g., mica plating) || || Lower shoreface sediments may be poorly swept; horizontal wells may improve sweep in favorable circumstances
|-
| Extensive layer-parallel carbonate cements below flooding surfaces || || Poor vertical connectivity
|-
| Mud-filled interridge swales in strand-plain sandstones || || Can create barriers to vertical flow with compartmentalization
|-
| Common tidal and fluvial channel fills || || Permeability contrast with shore face or barrier island sandstones can result in bypassed oil
|-
|
Lagoonal sandstone bodies (washover fans and flood-tidal deltas) can be wholly or partially enclosed in mudstone || || Can form discrete hydraulic units or compartments with bypassed oil
|}
==Parasequences and parasequence sets==
==Parasequences and parasequence sets==