Today the main geophysical exploration method used in the oil and gas industry, and the state of the art, is 3D seismic.
The use of advanced seismic techniques makes it possible to map the geological structure of the earth’s subsurface three-dimensionally, down to depths of 5,000–6,000 metres. Seismic exploration involves generating sound waves and picking up the echoes reflected by the subterranean layers of rock.
“Oil and natural gas are hydrocarbons formed from organic substances by biological, chemical and physical processes in the course of the Earth’s history. They migrate from the source rock and, under the right conditions, accumulate in the tiny pores of subterranean reservoirs.”
Kurt Sonnleitner, Chief Technical Officer, RAG
The differing densities and acoustic properties of underground rock strata make it possible to locate potential oil- or gas-bearing formations. The signals (seismic waves) emitted by special vehicles, known as vibrators, are reflected by the layers of rock and detected by arrays of receivers (geophones), usually with diameters of about 15 centimetres, on the surface. Seismic campaigns normally last for between four and eight months. Powerful computers at RAG headquarters use the data acquired in this way to generate images similar to ultrasound scans. It takes several months to process the raw data accumulated from millions of seismic traces. The results are then subjected to structural and stratigraphic interpretation by RAG’s geologists and geophysicists, enabling our experts to draw conclusions about the probability that oil or gas accumulations have been identified. However, proof of the presence of hydrocarbons can only come from a well.