Petroleos Mexicanos drilled 296 wells during 1966 compared with 361 drilled during 1965. One hundred and fifty-three wells were classified as exploratory holes, of which 77 were new-field wildcats that resulted in the discovery of 18 new oil and gas fields, a discovery percentage of 23.4.

Exploration activities:
Twenty surface geological parties, 21 seismic crews, 4 gravity-meter parties, 1 magnetometer party: total, 46 exploratory crews (compared with 43 which operated during 1965).

Annual oil production:
135,021,016 bbls, an increase of 2.18% from 1965.

Annual gas production:
529,203,404 Mcf, an increase of 7.3% from 1965.

Reserves:
Proved reserves of oil and gas equivalent as of January 1, 1967: 5,356.961 × 10⁶ bbls.

Drilling activities:
Total wells drilled: 296 compared with 361 drilled in 1965. Exploratory wells, 153, and development wells, 143, compared with 139 exploratory holes and 222 development wells drilled in 1965.

Discovery methods:
15 new fields were located by seismology, 3 new fields by subsurface geology and seismology.