Uses

The principal uses of the diamond core drill in the 1800's and early 1900's were in prospecting, mining and quarrying such as for coal in Pennsylvania, copper and iron in the Michigan and Minnesota ranges, gold in the Rand, etc.  One unusual use was for holes needed for blasting out the treacherous Hell Gate Reef which had posed a great danger for ships navigating New York Harbor (Edson, 1926).

The first commercial use of diamond core drilling for oil happened in 1916 and began to replace other rotary core methods such as the adamantine drag-type coring tool and the calyx toothed coring bit.  By the 1920's diamond core bits and drilling bits were in general use in the United States and were being used to drill into the limestone reservoirs of high pressure wells in the Tampico Basin in Mexico.

Petroleum geologists made considerable use of portable diamond core outfits to drill key bed holes, also called strat holes.  The recovered core allowed the stratigraphy to be studied in detail.  The tops of key beds were used for structural mapping which was part of the process to select a location for oil drilling.  This was in the late 1920's and 1930's before electrical well logging services and seismograph methods were generally available.

The Mid-continent, Gulf Coast and California were the main regions employing diamond core operations for oil in the U.S. in those years.  In the older eastern fields, such as the Bradford field on the Pennsylvania-New York border, diamond coring was carried out for water-flooding operations.

Diamond core of a hard sandstone.  The core has been sawed in half for examination purposes.  This 15 1/2 cm. core slab shows faint paper-thin lines of shale intercalated through the sandstone.  The value of a diamond bit is its ability to cut out whole cores with little damage to the retrieved core formation.  Cores like this are excellent for studying the characteristics of the rock.

These diamond cores of a reef formation from a New York well are being studied by Jorge Valdes-Latapia (left) and Samuel T. Pees.  The core has been cut into quarters for laboratory purposes.