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John F. Carll: The First Petroleum Geologist and Engineer

Jul 16, 2007 | Posted in Essays, People

2nd Sand Map

Second Sand Map

John Franklin Carll was born in Bushwick, New York, now Brooklyn, on May 7, 1828. Carll moved to Venango County, Pennsylvania in 1864. He settled in Pleasantville and began following the oil industry diligently, becoming familiar with drilling and production methods, making careful observations of the different rock layers penetrated in drilling, and collecting records on numerous wells. Eventually, because of his extensive knowledge of the various subsurface formations in the areas around Oil City, and his general habit of close observation, he soon received widespread acknowledgment in the Oil Region as a geologist. Local oilmen eagerly sought his advice on where and to what depth they should drill.

As his prominence in Pleasantville and the oil fields of Venango County increased, he had the opportunity to serve both the profession and his community. In the fall of 1868, he joined a committee of oilmen who attempted to gather more detailed information about drilling in Venango County. The committee tried to ascertain the degree of dip and the dip direction of the producing rocks and their relationships between the various producing areas. This occurred at a time when the fledgling industry first realized that the oil-bearing rocks differed between the Oil Creek area and other producing areas. For example, they were startled to find that the Fourth Sand of the Pleasantville area was actually at a higher elevation than the Third Sand along the Oil Creek Valley. One committee member, E. O. Nettleton, ended up doing most of the work alone, determining well elevations and collecting well records during 1868 and 1869. He left Venango County and turned all of his accumulated data over to Carll. Carll had little immediate use for the records, but held on to them. They soon proved most valuable.

An Act of the Pennsylvania Legislature in May 1874 ordered a Second Geological Survey of Pennsylvania to further the work begun during the First Survey of 1836-1841. J. Peter Lesley was appointed Director. Lesley appointed John Carll in charge of the Geological Survey in the oil districts of Western Pennsylvania.

Carll published his first report for the Survey, Report I, in 1875, only one year after his appointment. Before joining the Survey, he realized that many of the oil-bearing sandstones of the Oil City area persisted throughout the Region, and had already made great strides in defining the stratigraphic and lithologic characters of the “Venango Oil Sand Group”. Carll’s first volume was slim but contained an enormous amount of information concerning the oil sands throughout northwestern Pennsylvania. Probably the most important aspect of this report was Carll’s pioneering subsurface mapping. Carll stressed the importance of subsurface geologic structure in the oil fields and presented the first structure maps of subsurface formations published in North America.

Carll’s second report, Report II, was published in 1877. It was a compendium of well logs for 1,654 wells throughout northwestern Pennsylvania, as well as precisely surveyed elevations along the railroad lines. Many of the well records were those collected by the committee he belonged to in Pleasantville in 1868 and 1869, records given to him by E. O. Nettleton.

Many geological historians consider Carll’s third report (Report III) published in 1880, his magnum opus and one of the most remarkable books on early petroleum geology and engineering ever written. It included the surface and subsurface geology of the oil regions in Butler, Clarion, McKean, Venango and Warren counties in Pennsylvania. Also included were lucid, detailed descriptions and illustrations of a standard drilling rig and tools of the time and equally clear descriptions of drilling, “shooting” and production methods.

Carll published his fourth volume, Report 14, in 1883. It contained 685 well records and a thorough geological survey of Warren County including detailed geology by township. Carll’s final report, Report 15, was published in 1890. Carll recognized early in his career the necessity of keeping accurate driller’s records and devoted considerable energy attempting to convince the producers of the wisdom of this practice. Carll’s persistence in time paid dividends. The well records he collected for his seven published reports are used by geologists today in the old Pennsylvania Oil Region where the relative lack of modern drilling has otherwise limited the data.

Carll left the Pennsylvania Survey in 1888. Carll’s immense legacy of published reports based on his work with the Survey had little influence on the oil industry of the day. It would take almost 40 years to rediscover much of what he tried to tell oilmen during his short tenure with the Survey.

John Carll’s scientific methods and insistence on obtaining and retaining the best quality and most complete information resulted in many geological and engineering innovations that are still in use today. He was the first person to suggest collecting drill cuttings as a way of correlating them from well to well. He also invented the strip log. A strip log is a graphic representation of the rocks penetrated in the well bore combined with a description at various levels of the lithology, mineralogy, fossils and any other characteristics of note. Strip logs are still used today. He also was able to demonstrate the correlation of some subsurface strata with rock formations exposed at the surface.

Carll may have been the first to realize that the reservoir rocks in the prolific Bradford field in McKean County were not the same as those in Venango County. Drillers familiar with Venango County’s three producing sands used the same terminology in the Bradford field assuming the sand rocks were the same. Carll published a statement in 1876, early in the production history of the Bradford field, saying the Bradford producing sand, its third sand, was 1,000 ft. below the Oil Creek third sand. Facts revealed later proved Carll was close in his estimate.

Carll’s hypothesis on the geological origins of the reservoir sandstones of the Oil Region has been substantiated by more recent geological investigations. Carll was correct in theorizing in Venango County the major oil sandstones were deposited primarily as beaches, offshore barrier bars, spits, tidal bars and other shallow marine accumulations.

In a discussion about the importance of water in oil reservoirs in 1880, Carll was way ahead of his time. He stated, “The flooding of an oil district is generally viewed as a great calamity, yet it may be questioned whether a larger amount of oil cannot be drawn from the oil rocks in that way than by any other, for it is certain that all the oil cannot be drawn from the reservoir without the admission of something to take its place.” He had discovered a very important fact about reservoir rocks. That fact is you cannot have empty spaces between the sand grains. Something has to occupy those spaces be it oil, gas, water or some other fluid.

A genius and visionary in his time, Carll was largely ignored by the industry he sought to educate and improve. Though he inaugurated many of the subsurface geological methods employed today, they only came in to general use after a forty-year hiatus. Carll died in 1904 and was buried by his family in Flushing, New York. J. P. Lesley, the Director of the Second Survey, without equivocation made the statement in 1883 that John Carll created the Geology of Petroleum. Today, oil historians agree with Lesley and recognize John Carll as the man who nearly alone invented petroleum geology and petroleum engineering. The Society of Petroleum Engineers has been honoring Carll annually since 1957 by awarding the John Franklin Carll Award to a member whose outstanding technical and/or professional achievements have advanced petroleum engineering or the application of engineering principles to petroleum development and recovery.

Abstracted with permission from…

"John A. Harper, 2001, John F. Carll - The First Petroleum Geologist and Engineer." The Oilfield Journal, Winter 2001-2002, pages 2-14. The Colonel, Inc.

Courtesy of Friends of Drake Well, Inc., membership association supporting the Drake Well Museum; the Oilfield Journal publication is a benefit of membership. The complete article is available in the Oilfield Journal for sale in Museum Store at Drake Well.