Transforming ocean bottom seismic technology into an exploration tool

Abstract

It has been one of the enduring features of the oil and gas E&P industry that ocean bottom seismic (OBS) survey technology has yet to fulfil its potential. Ten years ago a similar observation was made (Berg, 2007). It was suggested then that towed-streamer surveys dominated the offshore survey market because the technology was wellestablished and inexpensive compared to ocean bottom techniques. The message was that an ocean bottom node (OBN) seismic acquisition could be ‘well worth the additional expense’. This was perhaps an unfortunate turn of phrase reinforcing an industry perception that seabed seismic was indeed a costly operation. In the intervening period, according to our best estimate, OBS surveys have in fact been slowly eroding the previous dollar value market share held by towed streamers, rising from around 4% in 2006 to approximately 15% in 2015 (see Table 1). It is also clear that the application of ocean bottom node systems rather than ocean bottom cable (OBC) is becoming the technology of choice for oil companies. More than 50% of OBS surveys now use some form of seabed node receivers (see Table 2). These have been developed over the years by a number of suppliers. Those OBC surveys that are being carried out are largely dependent on legacy systems with no similar record of recent innovation. We contend in this article that the technical case for node-based seabed seismic has been made in theory (See Ronen et al., 2009) and, in practice, judging by the increasing number of OBN surveys worldwide. It is also the case that in the current oil price crisis that oil companies for the foreseeable future are likely to concentrate their investment dollars on optimizing output from existing reservoirs in order to replenish reserves. This implies an increased role for OBS if the technology is offered at the right price point. We also believe that in a number of future exploration scenarios, e.g., complex geological settings in known oil provinces, OBN can be a more than viable alternative to towed-streamer solutions.