The Barnett Shale Play of North Texas: Current Issues
Kent A. Bowker
Bowker Petroleum, LLC, The Woodlands, TX
Many Barnett workers have an incorrect understanding of the Barnett reservoir of the Fort Worth Basin. No one has a complete understanding of exactly how this nonconventional reservoir actually works, but we have enough understanding to know that many of the ideas held by some Barnett workers are incorrect. For example, the Barnett is naturally fractured, but only a tiny fraction of these fractures are open. In fact, areas that have the most natural fractures, i.e., areas near faulting, have the lowest production. The huge concentration of gas in place is what makes the Barnett successful, along with the rock's mechanical properties. Structural folds are detrimental to Barnett production. Many Barnett workers believe that the Barnett south of Fort Worth is not overpressured (it is widely agreed that the Barnett has a pore-pressure gradient of 0.52 psi/ft in the “core” area of the field north of Fort Worth). The geologic history of the gas-saturated area to the south is nearly identical to the “core” area, implying the pressure regimes should also be similar. In addition, measuring the pore pressure in shale is difficult and not enough pressure data has been collected in the southern area to definitively determine the pore-pressure gradient there. Limestone beds within the Barnett are the result of submarine debris flows. The core area of Newark East field is not a sweetspot, it is just the first area that Mitchell Energy started drilling. One man is solely responsible for the success of the Barnett play: George P. Mitchell.