The Challenge of Precisely Positioning a 3D Seismic Survey

Abstract

The three-dimensional (3D) seismic survey is a relatively new technique used in the exploration and development of petroleum resources. It is well known that precise navigation (positioning) is required for the 3D seismic operation. However, it is not well understood why this high level of precision is required. In addition, few, if any, attempts have been made to discuss actual positioning achievements while performing a 3D seismic survey. This paper attempts to fill both these voids. In this paper, the 3D seismic survey is simply explained from basic principles and the position accuracy requirements are developed. State-of-the-art techniques and equipment are presented for positioning both the seismic vessel and the towed streamer containing an array of hydrophones. Results are presented for vessel positioning using the 450 MHz Syledis system in conjunction with a 2 MHz Argo system. A direct comparison of these two systems is given from data obtained during a 3D seismic survey. In addition, operational results are presented for the positioning of a towed hydrophone array. New techniques under development for positioning the seismic vessel and the towed hydrophone arrays are presented. The possible use of GPS technology for 3D seismic surveys is discussed and the system's impact for future work is evaluated.Conclusions are presented summarizing current 3D seismic accuracy requirements, the techniques and equipment required, results that can be expected, and what positioning technology can be expected in the future.