The last big oil discoveries were … ... long ago!
From the OP site:
"
8 The last big ones
Most of the massive oil field discoveries in the world were made before the late 1980s. Since then, discoveries of huge fields have been negligible in terms of numbers. In fact, the only really big oil discovery in the last 30 years was the Kashagan field in the Kazakh section of the Caspian Sea. The field has a maximum production capacity of 380,000 bpd, which was hit in 2019. Its development has not been free from trouble, cost overruns, and delays, but it continues to contribute a substantial part of Kazakhstan’s oil output."