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Siliciclastic shorelines and barrier island reservoirs (view source)
Revision as of 21:35, 12 August 2015
, 21:35, 12 August 2015→Back-barrier environments
==Back-barrier environments==
==Back-barrier environments==
Background deposition within the lagoon behind the barrier island is generally mud, but with some sand bodies present. These include washover fans and flood-tidal deltas ([[Figure 192]]). Washover fans form when storms pitch sand over the barrier bar into the lagoonal area. Flood-tidal deltas develop as a result of the tidal movement of sand through an inlet into the lagoon. These lagoonal sand bodies are characterized by a pinch-out geometry into the lagoonal shales. The shales interfinger with the sandstones, commonly enveloping the sandstones and sometimes isolating them as discrete hydraulic units.
Background deposition within the lagoon behind the barrier island is generally mud, but with some sand bodies present. These include washover fans and flood-tidal deltas ([[:File:M91FG192.JPG|Figure 7]]). Washover fans form when storms pitch sand over the barrier bar into the lagoonal area. Flood-tidal deltas develop as a result of the tidal movement of sand through an inlet into the lagoon. These lagoonal sand bodies are characterized by a pinch-out geometry into the lagoonal shales. The shales interfinger with the sandstones, commonly enveloping the sandstones and sometimes isolating them as discrete hydraulic units.
Washover sandstone complexes may be rather patchy and laterally heterogeneous. Production from washover sandstones in the Glasscock reservoir of the West Ranch field in Texas is described by Galloway (1986). Waterflooding has proceeded irregularly with injected water preferentially flowing along the washover channels. As a result, the Glasscock reservoir has the lowest projected recovery factor (38%) of all the major intervals in the West Ranch field.
Washover sandstone complexes may be rather patchy and laterally heterogeneous. Production from washover sandstones in the Glasscock reservoir of the West Ranch field in Texas is described by Galloway (1986). Waterflooding has proceeded irregularly with injected water preferentially flowing along the washover channels. As a result, the Glasscock reservoir has the lowest projected recovery factor (38%) of all the major intervals in the West Ranch field.