Print this pageLacustrine Deposits Examined as a Sratigraphic Control on 
Migration
and Compartmentalization
in Eolian Reservoirs
The Cedar Mesa Sandstone was deposited in an ancient sand
dune sea and is an exhumed stratum that has been a host for petroleum migration
and accumulation. The Sandstone consists of interbedded
and intertonguing eolian,
fluvial, pedogenic and lacustrine
strata. The focus of the research conducted is the small scale lacustrine, and associated pedogenic,
lithologies that formed when the water table was high
or when floods filled the interdune areas of the
ancient desert. These lacustrine and pedogenic zones are one example of barriers that will
affect the compartmentalization and migration of petroleum in a dune deposited
reservoir type. The geometric distribution of groups of ponds stacked within
sandstones is predictable using outcrop observations and wind direction to
reconstruct the dune topography. Lacustrine deposits
surveyed run parallel to the long axis of dunes in the interdune
areas and are found between beds where petroleum has migrated and where it has
not. Two end member types of lacustrine deposits were
recognized. Deposits containing dolomite, limestone and dolomitized
sandstone are interpreted as deposits of freshwater ponds fed by groundwater.
Deposits containing numerous shale beds were repeatedly inundated from
stream
floodwaters. Many lacustrine deposits contain both
shale and limestone and are interpreted to have formed in episodically flooded
groundwater fed ponds. The Cedar Mesa's interbedded lacustrine lithologies, their
thicknesses, and associated dune interaction zones are compared to better
understand how these depositional features may inhibit or enhance production of
eolian type reservoirs once they are buried and
matured.