SEISMIC INVESTIGATION OF THE MERRIMELIA FIELD

Abstract

The Merrimelia oil and gas field, 40 km north of Moomba in SA, is located on the central dome of the Gidgealpa-Merrimelia-Innamincka Trend within the Cooper/Eromanga Basins.

Geophysical studies have been instrumental in the investigation of the field since the discovery of commercial Permo-Triassic gas at Merrimelia- 5 in 1970 based on the results of the Merrimelia Seismic Survey. Subsequent seismic recorded during the 1980 Karawinnie Survey resulted in the location of Merrimelia-6 which, in 1981, discovered commercial oil in the Jurassic Namur Member and Hutton Sandstone, and Triassic gas, previously unknown.

To allow accurate mapping of the field's oil reserves, a detailed half kilometre grid was recorded during the 1981 Namooka Seismic Survey. The programme comprised 110 km of 24-fold Vibro- seis coverage. Interpretation of the seismic and well data has resulted in recognition of a complex stratigraphic component superimposed on the Merrimelia structural high. Considerable detailed seismic work has contributed to a better understanding of the seismic reflection sequence and hence improved geophysical prognoses.

Seismic studies of the Merrimelia field are continuing as further discoveries, most recently oil in the Triassic at Merrimelia-12 and gas in the Tirrawarra Sandstone at Merrimelia-13, are made in the field area.