Abstract

Colorado’s Wattenberg Field is a giant natural gas field by all measures. Discovered in 1970, it ranks as the seventh largest domestic U.S. natural gas field, with cumulative production exceeding 3.4 TCFE from six Cretaceous reservoirs including the Dakota, J, Codell, Niobrara, Hygiene (Shannon), and Terry (Sussex). The majority of Wattenberg’s production comes from two reservoir systems: the deeper J Sandstone and the shallower Codell/Niobrara sandstone and marlstone. The J and Codell/Niobrara reservoirs are blanket-like, laterally extensive sands and marls deposited under marine deltaic, sub-aqueous bar, bar-margin, shelf, and valley-fill processes. All reservoirs are classified as tight gas sands, exhibiting porosities of 9 to 20%+ and corresponding permeabilities below 0.1 md. Accordingly, hydraulic fracturing is necessary to extract commercial volumes from these tight reservoir packages.