Stratigraphy and Sedimentology of the Smackover Formation, Southwest Alabama

The Smackover Formation is a highly productive producer of hydrocarbons throughout the United States Gulf Coast region. More than four million barrels of oil and five billion cubic feet of gas have been produced from the Smackover Formation in the Barnett Field in southwest Alabama. Paleohighs formed during the Paleozoic and salt tectonic relief features control sediment distribution of the Smackover Formation in southwest Alabama. The Smackover in Barnett Field is entirely dolomitized, but the carbonate texture at the time of deposition is still visible in thin section. The Smackover carbonates in Barnett Field were deposited in the near-shore area of a carbonate ramp environment. The Smackover may be divided into three lithologic facies in this area; an ooid grainstone, oncolite packstone, and algal mudstone. Smackover deposition is interpreted to represent a period of eustatic sea level rise. Modern interpretations suggest the Smackover may have been deposited in three sequences. The Smackover in Barnett Field appears to represent a single stratigraphic sequence. The distribution of the three Smackover facies in Barnett Field suggests the formation was deposited during a sea level highstand following a rapid sea level rise. Accommodation of Smackover sediment led to a relative shallowing of the near-shore environment. The shallowing caused a prograding infilling pattern into the basin. The Smackover facies correlate to characteristic porosity and permeability values making the ability to predict the occurrence of a single facies vital to petroleum exploration