Print this pageOther Effects of Shale on Structure
| Salt dome effect | Where large bodies of shale have been carried up on
the flanks of rising salt domes, the shale can
substantially change the resultant structure as the shale
dewaters. The dips in beds abutting the shale flatten
with time, consequently reducing petroleum trapping
capacity. The structure contour map below of the Weeks
Island dome, Iberia Parish, Louisiana, shows this effect.
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| Down-to-the-coast faults | Late dewatering of shale may also substatially
influence the shapes of other Gulf Coast sutructures. The
figure below illustrates a down-to-the-coast fault
structure in Texas in which the upthrown block is now
deeper than the downthrown block because the shale in the
upthrown block has shrunk. The cross section below from
San Salvador and La Blanca fields, Hidalgo County, Texas,
shows this effect.
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| Differential compaction model | The figure below demonstrates the mathematical basis
of upthrown-now-deeper-than-downthrown situations
resulting from shale compaction and increase in sand
thickness in the original downthrown side of a fault.
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Table of Contents |
Table of
Examples of Shale Domes  |
