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Antrim Shale Natural Gas Play in Michigan: 30 years later, A Retrospective


The modern phase of natural gas production from the Antrim Shale in Michigan began in 1986 and peaked at nearly 200,000,000 MCF per year in 1998. Cumulative production through the end of 2014 was 3,390,577,266 MCF (nearly 3.4 trillion cubic feet) of natural gas. With over 11,000 producing wells completed over the past thirty years, the Antrim shale of Michigan is one of the most extensively drilled and longest-lived of the U.S. shale gas plays. After thirty years of developmental history it is useful to examine the past history of the play and speculate as to the future development that may be likely.

After the play production peaked in 1998, the average annual production decline has been around 4.5 percent. Development began on 40 acre unit spacing and progressed to 80 and 160 acre well spacing. Commercial development has been limited to a broad swath across the northern portion of the State of Michigan. It is limited up dip by the truncated erosional edge of the formation subcropping beneath the Glacial Drift and down dip by high salinity formational brine that inhibits growth of methanogenic bacteria that generated the biogenic gas.

Several areas of exploration have been attempted in other regions of the MichiganBbasin but have failed to yield commercial production to date. Limited tests in the basin center to explore the oil window have been likewise unproductive. Although some horizontal wells have been completed, most of the play was developed using vertical wells.