Full-waveform inversion (FWI) has become an enabling tool for 3D velocity-model building, especially in the shallow part of seismic image that is well probed by diving waves. Given FWI provides direct access to P-wave velocities, its application time-lapse (4D) studies obvious interest. Can 4D give fast small reservoir production-related velocity changes and compete with traditional time-shift results based on fully processed imaged reflection data? Also, what algorithmic developments may be...

Abstract A database of 109 earthquake focal mechanisms for Scandinavia and Svalbard has been compiled, comprising 29 new solutions. Stress directions extracted from these have calculated southeastern southwestern Norway, the Norwegian Sea Barents-Finnmark region. The principal horizontal stress is c. N45°W, indicates a clockwise rotation as one moves south to north, in accordance with trajectories that can be expected ridge push. data indicate southern Norway normal faulting regimes are more...

A comprehensive compilation of 112 earthquake focal mechanism solutions in Norway and adjacent areas has been completed, including 7 previously unpublished for recent earthquakes determined as part the NEONOR (Neotectonics Norway) project. Using method Gephart & Forsyth (1984), 97 on Norwegian mainland margin have inverted with respect to primary stress directions, which a regional basis best possible way could satisfy individual solutions. In doing this were divided into six zones...

Conventional marine seismic surveys typically mobilize a single vessel towing two airgun source arrays in front of spread ten or more streamers. The data acquired this way are narrow-azimuth and lack near offsets owing to the distance between sources streamers which can be range 100 200 m for inner cables up 500 outer cables. Several solutions, such as coil shooting (French, 1984; Ross, 2008) advanced multi-vessel operations (Mandroux et al., 2013), have been proposed deployed improve...

Variable-depth streamer acquisition is now widely used, achieving a bandwidth of more than 6 octaves (2.5 to 200 Hz) and excellent lateral resolution providing improved impedance reservoir analysis. This processing method based on towing the deep, using variable-depth profile optimized ensure receiver notch diversity at imaging stage deghosting that takes advantage diversity. For 4D monitors acquired with cables baseline consisting flat towed streamer, we must deal two issues. First,...

Time‐lapse (4D) seismic data at Ringhorne, Ringhorne East, Balder and Forseti in the Norwegian North Sea are used to monitor gas water movement within reservoirs improve reservoir simulation models, enabling cost‐effective field operations. The structural complexity of reservoirs, their proximity high‐impedance Cretaceous chalk, a modest predicted 4D signal required significant effort acquisition processing achieve successful final product. repeatability was significantly improved stage...

We have developed a time-lapse full-waveform inversion (4D FWI) workflow for permanent reservoir monitoring (PRM) data acquired over the relatively shallow, heavy-oil, Grane field in Norwegian North Sea. The was tested on elastic synthetic representing two vintages of PRM data, modeled with 4D changes velocity model derived from real modeling results, both overburden and at level. These could be recovered, albeit not as good resolution magnitude true effects. Application method to October...

Summary In this paper we present a new marine seismic acquisition technique initially developed to meet the imaging challenges of Loppa High in Norwegian Barents Sea. Two vessels operate tandem; one streamer vessel towing spread deep, densely spaced streamers, and source two or more sources. The is positioned on top spread. unique configuration facilitates zero-offset data. This, together with fact that both negative positive offsets are recorded, creates illumination density subsurface....

Time-lapse (4D) seismic data at Ringhorne, Ringhorne East, Balder and Forseti in the Norwegian North Sea are used to monitor water gas movement within reservoirs improve reservoir simulation models, enabling cost-effective field operations. The structural complexity of reservoirs, their proximity high-impedance Cretaceous chalk, a modest predicted 4D signal required significant effort acquisition processing achieve successful final product. repeatability was significantly improved stage...

Summary We present a new processing algorithm to co-datum two or more streamer datasets acquired with different cable shapes common depth. This method is applied early on in time-lapse sequence so that standard 4D co-processing, such as QCs and binning, can easily be performed. also show how we match the spectra of legacy baseline flat tow monitor data variable depth, they both have minimal ghost content. Applying this technique 2013 North Sea dataset several times without time lag, find...

Using highly repeatable permanent reservoir monitoring data from the Grane field in Norwegian North Sea we show 4D FWI results using with a seven-month acquisition interval between vintages. changes at level that correlate both injecting and producing wells. In addition, find good agreement comparing velocity differences to time-shifts time-strains fully processed imaged seismic reflection data. We discuss two methods used, potential limitations, further work. Overall, this case study...

PreviousNext No AccessSEG Technical Program Expanded Abstracts 2017Can variable-depth streamer be used for 4D purposes — with time-lapse conventional or variable depth acquisition?Authors: Patrick CharronEnrico ZamboniSalvador Pou PaloméAdeoye AdeyemiClaire GrubbErik HicksJean-Michel DépreyPatrick CharronTotal S.A.Search more papers by this author, Enrico ZamboniTotal Salvador PaloméTotal Adeoye AdeyemiTotal Claire GrubbCGGSearch Erik HicksCGGSearch and Jean-Michel DépreyCGGSearch...

Summary Leakage of oil and gas is associated with significant calcite cementation in the overburden Frigg Gamma Field. This makes seismic imaging field conventional streamer extremely challenging. Different approaches are tested: Source-over-cable acquisition, undershooting by ultrafar offset seismic, high resolution site survey imaging, improved depth Full Waveform Inversion (FWI) velocity model, diffraction PS processing OBC data. Combined, these have given a better understanding leakage...