Bit Technology - Diamond Bits

Diamond Bits

Diamond core bits were introduced into the oilfield in the early 1920's and
were used to core extremely hard formations. These early diamond bits
were very expensive, costing about twenty times the price of the roller bits.
Since performance was barely economical for coring, very little
consideration was given to diamond bits as a drilling tool.
By the 1940's, a much improved technique had been developed for the
manufacture of diamond bits. The diamonds were cast in a matrix of
tungsten carbide powder bonded together with a copper and nickel binder.
This change permitted the use of more complex bit designs and diamond
setting patterns. These changes resulted in the improved performance of
diamond bits, and reduced the cost of the diamond bits as compared to
roller cone bits. However, they still were ten to fifteen times the cost of
roller bits, and therefore limited to a “last resort” item.
Regardless of reputation, many drilling engineers were attracted to
diamond bits because of the ability of being able to stay on the bottom and
drill for longer periods of time. During the late 1950's several major oil
companies began research programs on diamond bits, and these studies
provided a much better understanding of the mechanics of diamond bit
drilling and the influence of hydraulics on the penetration rate. This, plus
subsequent developments of more erosion resistant matrix materials, led to
performance levels in the 1970's which provided cost savings on a regular
basis.