John Carll: Petroleum Geologist

HEYER, JEFFREY F., Cross Timbers Oil Company, Fort Worth, TX

The collection of accurate well data was initiated by a committee of five men in 1868. A questionnaire was sent to all operators in Venango County requesting the depth and thickness of the Venango sandstones. Other information such as the quality of the oil bearing rock and the color of the oil was also requested. The committee started out as a private venture funded by subscription. Unfortunately, most subscribers lost interest and the information was given to John Carll. One hundred and thirty-four well records were collected. The oldest well record published is from the Phillips Well Number 2 drilled in 1861 on Tarr Farm near Oil Creek. In 1874, Carll joined the Second Geological Survey of Pennsylvania and used the well data in his geologic studies of the subsurface oil horizons.Se eral field sessions were spent running topographic surveys because the elevations provided by the operators were incorrect.

The well data also suggests the operators knew little about subsurface geology. Carll recognized correlation problems early in his investigation, so in 1875, he published two stratigraphic columns.

After reviewing and correcting the well data, Carll constructed three cross sections and then drew structure maps on the top and the bottom of the first and third Venango sandstones. The structure maps were published in 1875 and represent the first attempt to illustrate the dip of the producing sands in Pennsylvania.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)