Abstract

Chevron and three partners began developing the East Ardmore structure near Ardmore, Oklahoma in 1974-75. The discovery well and first offset both produced gas from the Mississippian Goddard sands. The drilling program was abruptly halted when a zero sand well was drilled less than one mile from the producing wells, thus a structural prospect became a stratigraphic problem. A study of the Goddard sand on nearby Caddo Anticline was conducted to determine the sedimentary environment of the Goddard. These data were then used by analogy to help determine the Goddard sand distribution on the East Ardmore structure.

The sand study was used to help interpret the "3-D" seismic survey that was shot in an attempt to seismically map the Goddard sand distribution at Ardmore. The results of the "3-D" survey will be briefly discussed and data will be shown to explain the selection of the Chevron City of Ardmore 3-#1 drill site. The results of the study are summarized below:

A. The Goddard sands are marine and relatively discontinuous.

B. The Goddard sand interval at Caddo probably represents a submarine or barrier bar. The sands were carried by currents and collected as a sand shadow on the lee side of growing structures. The sands were subsequently winnowed of clay and silt.

C. Truncation of the upper part of the Caney shale on local structures indicates early structural growth.

D. The "3-D" seismic survey at E. Ardmore supports the idea that the Goddard sands are discontinuous and erratic.