Geologic Anaylsis of Primary and Secondary Tight Gas Sand Objectives Phase A&B

Finley (1982) listed geologic and engineering characteristics of over 30 blanket-geometry tight gas sandstones in a survey of 16 sedimentary basins. Emphasis was placed on defining elastic depositional systems and on using constituent facies as a method of evaluating the common features of stratigraphic units of different ages in diverse sedimentary and structural settings. Blanket-geometry tight gas sandstones considered suitable for future research by the Gas Research Institute were found to occur primarily within deltaic and barrier-strandplain depositional systems. An assessment of expected transferability of research results (extrapolation potential) was made between stratigraphic units, and more detailed study of six formations was recommended.

The Corcoran and Cozzette Sandstones of the Piceance Creek Basin and the Travis Peak Formation of the East Texas Basin and North Louisiana Salt Basin were recommended for research by the Gas Research Institute on blanket-geometry tight gas sandstones, and initial studies of depositional systems were begun. The Corcoran and Cozzette represent the barrier-strandplain system and contain barrier, offshore bar, and associated marginal-marine facies. Detailed studies of the Corcoran-Cozzette in Shire Gulch and Plateau Fields show shoreface sequences common to the lower parts of both units, and bay-lagoon and deltaic facies occur in the upper parts. The Travis Peak Formation represents a deltaic system, having a lower subdivision of progradational deltaic facies, a thick middle subdivision of braided alluvial deposits, and an upper subdivision of marginal marine deposits influenced by marine transgression. Sands greater than 50 ft thick are prominent in the middle subdivision in areas on the west flank of the Sabine Uplift. The Frontier Formation and the upper Almond Formation of the Greater Green River Basin and the Olmos Formation of the Maverick Basin are not recommended for further research, but should be considered when the need arises to test barrier, offshore bar, and possibly deltaic facies outside the two main research areas. The estimated gas resources associated with the Corcoran-Cozzette and the Travis Peak in Texas are 3.7 and 17.3 Tcf respectively. The Mancos "B" of the Piceance Creek Basin is not recommended for any additional research because its unique distribution of lithologies limits its extrapolation to a small group of shelf deposits, some of which have already been investigated. The extrapolation potential of the Travis Peak is largely to itself over a wide area of East Texas and North Louisiana. Extrapolation potential of the Corcoran and Cozzette extends to a large number of stratigraphic units, mostly within the Upper Cretaceous of the Rocky Mountain Region.