Short note: GPU accelerated 3D wave propagation and continuous coil shooting

Introduction

Throughout the history of reflection seismology, particularly since the large scale inception of 3D surveys, there has been a simultaneous desire to both improve acquisition geometries and also to reduce survey cost. At first glance these goals appear to be contradictory, and for the most case they are; however, this short note postulates that recent innovations in simultaneous source acquisition and in coil shooting could lead toward these stipulations.

Areas that exhibit complex salt geology, such as the North sea, the western Gulf of Mexico and offshore West Africa, are extremely petroleum-rich making the production of detailed, high resolution 3D images of these areas key in understanding and appraising such fields. Over the last 10 years there has been a proliferation of survey techniques that differ from or augment the usual single source streamer towed cable geometry. Methods such as multiple azimuth surveys (MAZ) (Manning, 2007) and wide azimuth surveys (WATS) (Verwest and Lin, 2007) are common. When compared to equivalent, traditional narrow azimuth surveys these images exhibit better illumination, more consistent amplitudes along reflectors and sub-salt coherency. However, whilst these methods improve image illumination they also greatly increase the cost the survey.

More recently, coil shooting has gained interest as a technique of acquiring more azimuth rich data without increasing survey costs as much as MAZ and WATS. It has been shown with synthetic data that over complex geologies coil shooting can provide more illumination and fill in gaps in 3D angle gathers (Buia (2009); Moldoveanu and Kapoor (2009)). Also recently the concept of simultaneous shooting (Aaron and Fromyr (2009); Ayeni and Biondi (2009); Tang and Biondi (2009)) within surveys has gained momentum, since this technqiue reduces acquisition time, which is generally considered to be 80% of a survey's cost. The problem with the latter technique is that when cable towed streamers acquire simultaneously shot data, the waves recorded tend to be conical, rather than spherical, due to the motion of the source vessel. This gives reduced angular illumination compared to an equivalent, conventionally shot survey. We suggest that combining continuous shooting with coil shooting will help to both reduce acquisition costs and fill in illumination holes seen in 3D angle gathers.

Short note: GPU accelerated 3D wave propagation and continuous coil shooting