Equipment Specs

Cable Tool Drill

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Antique Cable Drilling Rig
A cable tool drill, also known as a percussion drill, is a machine that uses repeated penetration to bore holes into materials such as rock, soil, and cement. The cable tool drill has been around for as long as 4,000 years, and was traditionally used for drilling brine holes. It later became useful in oil drilling, operating on the first modern wells in North America.


[edit] History

Cable tools likely originated from a form of bamboo drill used in China more than 4,000 years ago. Used for drilling brine, the bamboo drill could bore up to depths of 3,000 feet (914 m). Although a form of cable drill was invented early on, and was used on projects well into the 1800s, the cable tool drill as we know it today was invented in 1825.[1]

Early cable drills were made of manila hemp rope, and that is, in fact, where the cable drill derives its name. The rope suspended wooden drill rods and drill tools to hoist the string of the tool up and down a spring pole or walking beam. The drill bit, which consisted of a blunt chiseled tip, would repeatedly chip away to expose a hole.

From the 1800s onwards, the manila rope was replaced with multiple-strand steel rope. The new improvements were the result of the growing brine-drilling industry in the U.S. The nature of brine-drilling required tools that could bore circular holes to a depth of 1,000 feet (305 m).

The drilling of the first spring pole well in the U.S. was initiated in 1806 by two brothers, David and Joseph Ruffner. The spring pole well, which was located off the bank of the Kanawha River in Charleston, West Virginia, took three years to complete, with the Ruffner brothers and crew drilling about 58 feet (18 m) deep—40 feet (12.2 m) of which consisted of bedrock.[2]

[edit] Oil Drilling

The success of the cable tool for brine drilling made it an obvious solution for oil drilling. The first commercial oil well in North America took place in Petroila, Ontario in 1885. Operating on a cable tool drill rig, it consisted of an 82-foot (25-m) high wooden derrick mounted on several huge timber logs. The legs of the derrick measured two by 12 inches (5.1 by 30.1 cm), and were positioned to form a right angle. Horizontal girts and diagonal struts were bolted to the legs of the derrick, and three cable reels were wound using steel cable up and down the crown block shives. Of the cables used, one was for drilling the line, one was for the bailer, and the last was for the hoisting and lowering of the casing. Power for these lines was generated by a steam engine located in close proximity to the derrick.

The derrick was positioned closely to a bailer, an apparatus used to bail out the cuttings and water debris produced by the drill. In addition, it used a Sampson post mounted on a platform with the derrick. The post lay horizontally and was attached by a hinge to a walking beam. The walking beam was used to hold a clamping device that dipped the drill. The drill bit, consisting simply of a steel weight with a point, was hoisted above the well by a cable.

On the end of the walking beam was a band wheel that had to be cranked in order to turn the wheel. When this action was complete, it would subsequently raise and lower a pitman, rocking the beam up and down in a “teeter-totter” motion, hence raising and lowering the drill. The constant repetition of this movement resulted in the penetration of the steel drill bit into the formation, thus producing a hole.[3]

[edit] Features

The cable tool features the following components:

  • A drilling cable for lifting and turning tools, as well as controlling the motion of the tools
  • A swivel socket to connect the cable to the tools and enable the cable to unwind
  • A drill stem that provides weight and guides the bit in the direction of the desired drilling
  • A drill bit that is responsible for penetrating and crushing rock
  • A driving case, where the force of the clamp is provided. A casing is a calf wheel mounted inside a derrick and used to operate a traveling block.
  • A drill rig might also comprise a drilling jar that keeps the tools from jamming together.
  • Another additional feature is a shock absorber, which rebounds the tools off the rock when it finishes striking the rock surface.

[edit] How it Works

Prior to the machine’s operation, the drill is synchronized with the gravitational fall of the other tools to ensure that when it strikes the rock, it will be powerful enough to chip away rock cuttings. Synchronizing the speed of the engine with the fall of the tools helps ensure that the driller is getting the most out of the cable tool drill.

When the synchronization is complete, the process begins by driving the casing to the top of the drill stem, a hammering action provided by the drive clamps. The clamp’s surface acts as a hammer face, allowing the case to use it as a weight. When the casing is lowered, the bit is inserted and water is ejected to create slurry to make it easier to remove the cuttings. At this point, the drilling ceases and the bailer is inserted to remove the cuttings, water, and any other debris that has built up. Different types of bailers are suitable for different applications. For example, the dart valve bailer is best for the collection of well-mixed cuttings.

The driller continues this process until the desired depth of hole has been reached. From day to day, the driller positions the cable line and begins hoisting and lowering the line so that it goes as far as it can. At points throughout the drilling, the driller will slacken the line to allow the drill to extend further down the hole. [4]

[edit] Advantages and Disadvantages

There are several advantages and disadvantages associated with this tool. On the side of advantages, it is cheap, easy for a single person to use, and it operates with good fuel efficiency. It has been criticized, however, for not being the most productive tool for drilling, as it is more effective for some formations than others.[5]

[edit] Common Manufacturers/Brands

[edit] References

  1. Drilling History. NTL World. 2008-10-12.
  2. Cable Drilling. Petroleum History Org. 2008-10-12.
  3. Cable. Lloydminster Heavy Oil. 2008-10-12.
  4. Drilling Methods. Well Drilling school. 2008-10-20.
  5. Drilling Methods. Well Drilling school. 2008-10-20.