CABLE-TOOL DRILLING

Cable-tool was the first method used to drill a bore hole and is still in use, particularly for shallow oil or gas wells in the Appalachian Basin.  The cable refers to the manila hemp rope used to suspend the wooden rods and the drilling tools in the earliest operations.  The manila line and wooden rods were eventually replaced by multiple-strand steel rope often called wire line or wire rope.

The cable (manila rope or wire line) pulls the string of tools up and down as brought about by a spring pole or a walking beam at the surface.  The heavy bit has a blunt chisel end which cracks, chips and smashes the rock by the repeated blows delivered in a measured or regular cadence.

When the objective was brine in the first half of the 1800's, small diameter cable-tool holes could have theoretically been drilled to about 1000 feet by this spring pole method, but the vast majority of those wells were of much less depth.  A handful of potable water wells around the world exceeded 2000 feet in those early days.  They usually took years and great luck to drill.  Oil wells in Oil Creek Valley generally ranged from 400 to 550 feet deep, but spring-pole drilling often stopped at about 200 feet and steam power took the wells the rest of the way, if it was available and affordable.

The first adequately documented spring-pole well in America was drilled by David and Joseph Ruffner beginning 1806 and completed January 15, 1808, on the bank of the Kanawha River near Charleston, West Virginia.  They reached a total depth of approximately 58 feet of which 40 feet was in bedrock.  It was a salt well.  The Ruffner brothers were the inventive pioneers of drilling in North America.  They even tubed the well with wooden pipe to prevent weaker salt water from mixing with the brine of their main pay zone.  Their feat spurred the salt industry and eventually led to spring-pole drilling for oil.

Percussion drilling is another name for cable-tool drilling.  It refers to the blows delivered to the rock by the bit.