Geophysical Prospecting doi: 10.1111/j.1365-2478.2011.01036.x Full waveform inversion and distance separated simultaneous sweeping: a study with a land seismic data set Ren´ e- ´ Edouard Plessix 1∗ , Guido Baeten 1 , Jan Willem de Maag 1 , Fons ten Kroode 1 and Zhang Rujie 2 1 Shell Global Solutions International, Kesslerpark 1, 2288 GS, Rijswijk, The Netherlands, and 2 BGP international, Fanyang road, PB 072751, Zhuozhou city, P.R. China Received May 2011, revision accepted November 2011 ABSTRACT Dense, wide-aperture and broad frequency band acquisition improves seismic imag- ing and potentially allows the use of full waveform inversion for velocity model building. The cost of dense acquisitions however limits its applicability. Blended or simultaneous shooting could lead to a good compromise between cost and dense ac- quisition, although the cross-talk between simultaneous sweeps may reduce imaging capabilities. Onshore, a compromise is achieved with distance separated simultane- ous sweeping acquisition, because the shots are easily separated when the processing focuses on pre-critical reflected events. Full waveform inversion for velocity model building however relies on post-critical reflected, refracted and diving events. These events can interfere in a distance separated simultaneous sweeping acquisition. By using a single vibrator, single receiver data set recorded in Inner Mongolia, China, a distance separated simultaneous sweeping data set is created to study the robustness of full waveform inversion in this acquisition context. This data set is well suited for full waveform inversion since it contains frequencies down to 1.5 Hz and offsets up to 25 km. Full waveform inversion after a crude deblending of the distance separated simultaneous sweeping data set leads to a result very similar to the one obtained from the single vibrator, single receiver data set. The inversion of the blended data set gives a slightly less good result because of the cross-talk but it is still quite satisfactory. Key words: Simultaneous shooting, Full waveform inversion. 1 INTRODUCTION Seismic data acquired with active sources are the main source of information on the Earth’s subsurface in exploration geo- physics. The resolution and accuracy of the images derived from these active seismic source experiments notably depend on the source and receiver distribution, the frequency spec- trum and the signal-to-noise ratio. Over the past decades, thanks to equipment improvements, the signal-to-noise ra- tio has greatly increased. We went from zero-offset to dense ∗ E-mail: ReneEdouard.Plessix@shell.com long-offset and wide-azimuth data acquisition and the fre- quency spectrum of the data has been widened, with nowa- days frequencies down to almost 1 Hz (Plessix et al. 2010). With the increase of computer power, this leads to the de- velopment and the use of more accurate imaging techniques, for instance reverse-time migration and full waveform inver- sion in which the so-called two-way acoustic wave equation is solved (Baysal, Kosloff and Sherwood 1983; Lailly 1983; Tarantola 1984; Pratt et al. 1996; Virieux and Operto 2009). These dense data acquisitions are rather time consuming and expensive to record. Using a single source approach and waiting for the vanishing of the signal between shots should give the best data quality. It may however be unaffordable C  2012 European Association of Geoscientists & Engineers 1