ABSTRACT

A chenier is an elongated sand body representing the remains of a stranded beach, that grades both landward and seaward into gulf bottom sand and silt and marsh deposits.

The recent cheniers are composed of, from top to bottom; first, highly organic silt or clay; next, an oxidized, limonitic, fine to medium grain sand with irregular patches of organic material composed primarily of decayed roots, third, strongly oxidized, limonitic sand and shelly sand with ripple marks, cross bedding, cut and fill structure and thin clay laminae, and fourth, a unit of shell beds alternating with silty sand. The units are separated vertically by diastemic breaks and would probably form separate reservoirs within each sandy unit. Both along trend and transversely, these units grade into highly organic silty clay and massive clay. Because of these facies changes, these sand bodies have the potential of becoming excellent stratigraphic traps for hydrocarbons.

Effective porosity and permeability is basically parallel to the trend of the chenier rather than to the dip which would be the normal dip direction in the Gulf Coast.