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The AAPG/Datapages Combined Publications Database

AAPG Bulletin


Volume: 68 (1984)

Issue: 12. (December)

First Page: 1924

Last Page: 1925

Title: Consideration of Possible Productive Zones Within Gatesburg and Postsdam Formations, Northwest Pennsylvania: ABSTRACT

Author(s): Marc A. Miller, Bruce A. Bennett, Gary G. Lash


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A recently drilled Cambrian test well in Waterford Township, Pennsylvania, penetrated Precambrian basement at a total depth of 7,342 ft (2,238 m). The well site was determined on the basis of structural contour mapping of the top of the Queenston Shale. This work has lead to the definition of a conspicuous structural high (anticline, horst-block?) characterized by about 250 ft (76 m) of relief. The steeply inclined southeast limb of the structure may control gas production within the younger Paleozoic formations and ultimately in older formations (e.g., Cambrian Gatesburg and Potsdam). Interpretation of structure, lithologic characteristics, and log analysis reveals two target formations--the Gatesburg Sandstone and the Potsdam Sandstone. The upper sandy section of the Gatesburg Sands one, a clean, yellowish-white quartzarenite of Late Cambrian age was penetrated at a depth of 6,280 ft (1,914 m) and was found to be water saturated between 6,340 and 6,370 ft (1,932 and 1,942 m). The productive zone is targeted between 6,415 and 6,447 ft (1,955 and 1,965 m) and contains approximately 13 ft (4 m) of pay that averages 8% porosity. Silica is the dominant cementing agent. The Potsdam Sandstone was encountered at a depth of 7,143 ft (2,177 m), just below a dolomitic interval of the lower Gatesburg. The productive zone ranges from 7,250 to 7,294 ft (2,210 to 2,223 m) and is characterized by 10 ft (3 m) of sand that averages 7% porosity. Calcite is the dominant cementing agent within the target zone.

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