Tilted fault blocks, with Middle and Lower Jurassic reservoir intervals, below the late Kimmerian unconformity are the main exploration targets in the northern North Sea. The 34/10 Delta is one of the biggest structures on the unconformity level. Because of poor subunconformity seismic data quality on early records, Jurassic reservoir intervals could not be positively identified. On seismic data collected in 1974, high-dip events below the late Kimmerian unconformity were identified as Jurassic events. These data, reprocessed in 1976, were used in the final mapping before the first well was drilled in 1978. A prospect evaluation based on regional geology and analogies with similar structures in the region gave high hopes for the 34/10 Delta prospect. The 34/10 Del a structure was declared commercial in 1980. Recoverable reserves are estimated to be 0.24 10⁹ cu m (1.5 10⁹ bbl) of oil.