Well No.4 (CSO-4)

 oil field, historic landmark, memorial plaque, oil/gas well

The first commercial oil producing well west of Pennsylvia and eventually the longest producing oil well in the world (1876-1989)
In 1875 Charles Mentry, an experienced Pennsylvania oil driller, leased the Baker and Beale claim at Pico Springs (henceforth called Mentryville) and put together a partnership with Denton C. Scott and John G. Baker. (Baker would later sell out to Christopher Leaming.) Mentry put down the first well with a spring-pole drill and got a good flow of oil. The partnership also drilled two other wells.
In February of 1876, Sanford Lyon (a minority owner of the Beale and Baker claim) drilled a 170 foot well near the three Mentry wells. In June or July of 1876, the Mentry partnership sold out their interests (the Pico Spring lease from Beale and Baker) to the newly formed California Star Oil Works Company of San Francisco headed by Demetrius G. Scofield. CSOW also bought out the claims of Pico, Wiley, Gelcich, and Lyon. This became the nucleus of the new company, which Scofield had organized with the backing of his firm of Frederick B. Taylor and Company. Mentry was hired as the superintendent, a position he held until his death in 1900. CSOW obtained permission to drill on the Pico lease from Beale and Baker.
In July 1876, Mentry started this well, CSO-4, with a crude, human powered drilling devise called a spring pole. (In August 1877 it was deepened to 610 feet using the first steam engine in the canyon.)
From California Star Oil records, written by Mr. Mentry:
"CSO-4: Commenced drilling August 1876, Completed drilling Sept. 26, 1876. Caved badly at 270'. First oil at 250' in shale. Tubed and pumped at 370', producing 25 barrels daily for some time. In August 1877, commenced to deepen well. At 560' the well was flowing 70 barrels daily, and was still flowing in April 1879 when it was rigged for pumping. In 1885 it was deepened from 610 to 1,030' but it is thought the only good attained was in consequence of cleaning it out."
Initial production in 1875, at depth of 370 feet was 25 barrels per day.
Maximum production, at 560 feet, was 70 barrels per day.
The well eventually reach a maximum depth of 1,400 feet.
The final productivty CSO-4 was just one barrel per day in 1989, after a world record of 113 years of production. In February 1990, CSO-4 was officially capped and abandoned. So as to not affect the well's status as a National Historic Landmark, Chevron received special permission to leave pipes on the surface at the wellhead, although the pumping equipment was all removed.

The black and white photo by Carleton E. Watkins shows CSO-4 on 26 June 1877.
The color photo shows CSO-4 132 years later, on 26 June 2009.