Drilling:
In 1971, Petroleos Mexicanos drilled 516 wells, 7 less than in 1970. Of the 516 wells, 129 were exploratory, and of the exploratory wells, 10 did not reach their objective because of mechanical failure. A total of 387 development wells also was drilled.

The total footage drilled during 1971 was 1,316,827 m (4,311,635 ft). Of this amount, 423,467 m (1,387,277 ft) was exploratory drilling, 6.2% more than in 1970. The average depth of the exploratory wells was 3,264 m (10,708 ft), 210 m (640 ft) more than in 1970. The average depth of the development wells was 2,358 m (7,708 ft).

The success of new-field wildcats increased from 18.8% in 1970 to 22.6% in 1971. The success of other types of exploratory wells increased from 28.3% in 1970 to 31.8% in 1971.

Exploratory activities:
(1) Exploratory parties: During 1971, 73 exploration parties were in operation. Of these, 27 did field mapping; 16, subsurface mapping; 23, seismic mapping; 5, gravity meter; 1, land magnetometer; and 1, combination magnetometer and gravity meter. (2) Exploratory wells: In 1971, 129 exploratory wells were drilled. Of these, 10 did not reach their objectives, because of mechanical failure. Of the 119 completions, 81 were new-field wildcats resulting in 8 oil wells and 9 gas wells for a 22.6% success. Of the dry holes, 41 were extension wells on producing structures and 7 were stratigraphic tests in new areas. Of the exploration wells which were not new-field wildcats 14 resulted in producing wells, for a 31.8% success.

Annual production of oil and gas:
The annual production of crude oil and condensate during 1971 was 177.3 million bbl. Daily liquid production was 485,681 bbl and daily gas production was 1,762.8 MMcf. Total annual gas production was 643,416 MMcf.

Reserves:
At year end, the reserves of oil and gas (thermal equivalent) reached 5,428.3 million bbl, a decrease of 139 million bbl from 1970.