US Examples

Only four examples of shallow, basin margin gas accumulations are described here. They are major plays that are fairly well documented in the literature. None of these four are in Cretaceous units and all are outside of the Rocky Mountains (Leads: Figure 3)

ANADARKO BASIN--NORTHEASTERN MARGIN

The giant Hugoton Gas Field in southwestern Kansas is one of the largest in North America. Nonassociated thermogenic gas is produced from Permian clastics and carbonates. As described in the “Ideas” section of this website, the Hugoton Gas Field is the archetype for thermogenic gas that has migrated up to shallow depths on the basin margin. The Kansas Geological Survey has an ongoing study of the accumulation (www.kgs.ukans.edu/Hugoton/).

The trap is complex, including a stratigraphic pinch out to the north and west, local fluid compartments controlled by faults, and a possible hydrodynamic component. Depths are generally 2000-3000 ft. More than 23 TCF has been produced from an area of over 4100 sq mi.

The Hugoton Gas Field was discovered in the 1920’s and the initial production was locally consumed. Subsequent development supported a pipeline infrastructure to the upper Midwest. During the 1980’s, state authorized in-fill drilling greatly increased production.

MICHIGAN BASIN--NORTHERN MARGIN

On the northern margin of the Michigan Basin, natural gas is produced from fractured Antrim Shale (Devonian). This area in the northern part of Michigan’s Lower Peninsula is the archetype for late generation biogenic gas. The gas was generated in the relatively recent geologic past and is in young ground water that is flowing down the basin margin, away from subcrops beneath glacial drift. The Gas Research/Technology Institute has funded several studies by University of Michigan people (www.gastechnology.org, Report GRI-97/0127).

Attempts to extend the play to other margins of the basin have met with only limited success. The western margin seems to show the best potentials.

ILLINOIS BASIN--EASTERN MARGIN

The New Albany Shale in the Illinois Basin is similar to the Antrim. On the eastern basin margin in western Indiana, biogenic gas has been produced in a setting similar to the Michigan play. The late generation biogenic gas has large amounts of co-produced water. The Gas Research/Technology Institute has also funded research in the Illinois Basin (Walters and others, 2000, GasTips).

APPALACHIAN BASIN--NORTHWESTERN MARGIN

Shallow gas has been produced from the historic Lake Shore Fields located on the northwestern basin margin. The gas is either biogenic or migrated thermogenic gas. The hosting rocks are silty and sandy beds in black shales (Devonian/Mississippian) with low thermal maturity (Milici, 1993). These accumulations have not received much modern attention. Most of the exploration activity has been directed toward thermogenic gas in the basin center.