Exploratory drilling showed a significant increase over the 1955 totals, 1,099 tests in 1956 compared with 876 exploratory tests in 1955. Development drilling in 1956 was about on a par with 1955 activity, a total of 6,560 in 1956 compared with 6,604 in 1955. Although fracturing still plays a key role in exploration, there is a definite trend toward emphasizing stratigraphic traps rather than structure. This line of thinking has been most successful in finding new reserves in the Anadarko basin of northwestern Oklahoma. Seismic activity decreased slightly when compared with the previous year. Secondary recovery and production from the unallocated or “stripper” oil fields accounts for more than half the state’s oil production.