Total drilling activity in North America in 1968 amounted to 37,444 wells and 169,232,679 ft of hole compared with 38,183 wells (FOOTNOTE 4) and 162,924,271 ft⁴ of hole reported in 1967. This represents a decrease of 2% in number of wells but an increase of 4% in total footage drilled. Canada and Mexico showed increases in both total wells and footage. The United States experienced a decline in the number of wells drilled but an increase in drilled footage.

Exploratory drilling in Canada and Mexico showed increases in both wells and footage, whereas in the United States, the number of wells declined and total footage increased. Actual figures for exploratory wells, with corresponding 1967 values in parentheses, are: Canada, 1,609 wells (1,448) and 7,543,693 ft (6,420,367); Mexico, 138 wells (135) and 1,331,996 ft (1,295,160); United States, 8,879 wells (9,059) and 50,958,038 ft (49,124,222). A total of 1,785 exploratory wells out of a total of 10,626 were found to be capable of hydrocarbon production. This gives a North American "success ratio" of about 1:6 (16.8%) compared with 1:5 (19.4%) in 1967. Canadian exploration success was stable at 28.2%, the same as in 1967. Mexican exploratory discoveries resulted in an increase in success pe centage from 23.7 in 1967 to 27.5 in 1968. In the United States, the percentage of successful exploratory wells decreased from 17.6 in 1967 to 14.6 in 1968. This is the lowest success percentage since these statistics were first compiled in 1946.

The continued downturn in exploratory drilling and discovery ratio in the United States must, however, be weighed against the fact that 2 of the discovery wells found fields on Alaska's north slope which, in terms of our total hydrocarbon reserves, will possibly be more significant than any other discoveries in the history of this survey. Reserve estimates made by the committee indicate that, excluding the 2 discoveries on Alaska's north slope, the United States exploration effort found somewhat less than 1 billion bbl of oil and just under 6 trillion cu ft of gas. These volumes are approximately the same as in 1967 and were found with fewer, but deeper, exploratory wells.

The determination of whether the industry in the United States during 1968 experienced one of its worst years (based on "success percentage") or one of its best (based on volume of hydrocarbons found) must be left to individual judgment.