SEISMIC SURVEYING 


Latest trends in seismic acquisition technology


 Global spending on seismic has reached 7 BUSD in 2011, and is expected to increase by ~30 per cent. This investment is a result of the need for more, better and cost-effective data, and the response of the seismic industry is strong, with innovative solutions being developed to meet this challenge. Eric de Graaff explains.


A


dvances in seismic technology have driven much of the improvement in our ability to explore for new oil


and gas, to develop fields more effectively and safely, and to monitor production. Some of these advances have followed an evolutionary path, like the ever increasing numbers of sensors and streamers, improved spatial sampling, and imaging and migration algorithms. Other approaches, like the switch from 2D to 3D, the introduction of Wide Azimuth surveys, and seabed technologies have more suddenly changed the landscape. Passive seismic has emerged as an effective tool to monitor fraccing and injection, and may evolve into a technique which is capable of monitoring more subtle changes in the reservoir reliably. Recently, a lot of focus has been put on


Fig. 1. Noise suppression and footprint removal.


ways to increase the bandwidth of the data, and some interesting ideas and approaches have been proposed. In addition, several technologies have been introduced that increase the cost-effectiveness of data acquisition.


Te quest for more densely sampled data is most evident in the onshore efforts, where the vision of a million channel system is rapidly becoming reality, through the introduction of low weight sensors and wireless communication. In offshore seismic acquisition, the towed


streamers can easily decrease the sensor spacing in inline direction, for instance in the Q implementation, but improved cross-line sampling is more difficult to achieve, leaving an asymmetrically sampled wavefield. Te emergence of wide azimuth


acquisition is an effective solution for this asymmetry, but the significant costs drive this acquisition to areas with very significant illumination challenges, for instance in pre-salt targets. Te use of ocean bottom nodes is opening up the way to achieve good sampling by dense shooting, but the cost effectiveness of this method would need an improvement by a factor 3-5 to become a mainstream alternative to towed seismic. Te search to increase the bandwidth of the data has seen the introduction of dual


Raw stack 11 IHSS


Noise suppressed


5D interpolated


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19