Time-Lapse Dual-Source and Hexa-Source OBS Imaging for the Edvard Grieg Field

Following the conventional 50 x 25m dual-source acquisition of the 2022 monitor survey over the Edvard Grieg field, a 1.8 by 8km area to the north of the field was acquired again with a denser hexa-source (six source array) configuration. Shot interval was reduced to 1.7 seconds resulting in the subsequent shot energy (N+1) directly overlying the target reservoir interval. Iterative Source Separation with Priors (ISSP) technology was deployed to evaluate whether the primary signal could be successfully recovered and deliver comparable 4D results and metrics to the production dual source 4D configuration. 4D differences were generated with the conventional 2016 baseline survey and attribute extractions at the target reservoir interval showed good replication of the key 4D signal event and low NRMS values through the overburden and at target depth, <7%. Due to the denser shot spacing (25 x 25 m) and closer to point source configuration of the hexa-source gun layout, some uplift to 3D image was also observed in the signal content at frequencies above 90Hz, providing some additional benefits for the shallow event resolution above 800ms.