Results of recent seismic acquisition trials and near surface correction comparisons in the Cooper and Eromanga Basins

Abstract

The economic constraints brought about by low oil prices make it necessary to maximise the structural and stratigraphic resolution of our seismic data while still being subject to these economic constraints. Thus, whenever any new technology or procedures become available, the cost impact of any parameter changes must be carefully considered against the potential technical benefits achieved. This paper reviews some of the acquisition trials carried out during 1989?1994 and discusses the impact of those trials on the current acquisition parameters utilised in the Cooper and Eromanga Basins. The modification to parameters and procedures brought about by these trials has seen the productivity of seismic crews increase from 1.36 km/chg hr in 1988 to over 1.85 km/chg hr during 1992?1994. Thus, average monthly production in excess of 400 km/crew month in 1988 has increased to 550?600 km during the last few years, with the remarkable totals of 651 km and 665 km achieved in July 1993 and March 1995 respectively. The main acquisition parameters analysed include group interval/receiver array length and source effort. The opportunity to use 60,000 lb vibrators is considered to have given a 10?15 Hz increase in bandwidth at the high frequency end. This means that the previously perceived 65 Hz ceiling, which was considered to be caused by high transmission losses in the shallow section (Q = 25), is no longer restricting the bandwidth. Further investigations into static control techniques have demonstrated that the refraction method has been unable to match the results gained from upholes, whereas subsequent upholes drilled to check residual static profiles generally add confidence to the use of residual statics tied to upholes.