Antrim shale fractured reservoirs: Their potential throughout the Michigan Basin

Antrim shale gas production grew from 0.4 Bcf in 1987 to 156 Bcf in 1994, causing record gas production in Michigan. Recent industry activity suggests the play will continue to expand. The GRI Hydrocarbon Model contains an Antrim resource base description that was developed in 1991. It was based on industry activity through 1990 and only covered the northern extent of the Antrim surrounding the current play. Significant technological improvements since then have resulted in projected near-term production lagging actual production by one to two years. Even so, the 1996 Edition of the GRI Baseline Projection predicts Antrim production will reach 1 Tcf by the year 2015. Given the 1996 projection results, a reassessment of the potential for producing gas from Antrim shale-type fractured reservoirs was initiated. The analysis identified general geological characteristics that appear to contribute to successful wells and extrapolated them to the rest of the Michigan Basin. Data used included production and well data through 1995, GRI-funded studies, and proprietary studies and data on the Antrim and deeper formations significant to gas origin and thermal maturity. Initial results suggest four {open_quotes}Resource Areas{close_quotes} based on comparison to the existing play using the following geological factors: (1) extent andmore » thicknesses of the Lachine and Norwood organic shales; (2) regional structural expression of potential fracturing; (3) total depth relating to probability of open fractures; and (4) probability of biogenic gas contribution.« less