There would be several ways to drill into such reservoirs, and obviously, if near-vertical penetration from a surface location upon the actual producing-formation outcrop occurs, a large amount of gross pay will be encountered. Thus, the question becomes, “Will a suitable trap be found?” Fault traps appear possible, as shown in the images.
Additionally, pressures indicate faults may exist:
“Although the overlying Codell-Niobrara reservoirs are overpressured, the Muddy (J) Sandstone is underpressured. An original formation pressure of 2,750 psi was reported by Higley and others (2003). The depth of the Muddy (J) Sandstone is about 7,000 ft, so the formation is clearly underpressured, because the pressure-depth ratio is less than the hydrostatic gradient of 0.433 psi/ft that characterizes fresh water.
. . .
A [test-version] numerical flow model . . . (Belitz and Bredehoeft, 1988) . . . also showed that the Dakota J interval must be hydraulically isolated from recharge areas along the Front Range of Colorado where rocks of Dakota age crop out. Hoeger (1968) noted that although the Dakota Group crops out at relatively high elevations along the Front Range, those outcroppings seem to have little influence as a high-potential water source on the regional hydrodynamic environment of the J system in the Denver Basin, and he conjectured that regional flow barriers, possibly faults or a facies trend of low transmissibility, must be present to provide that isolation.”