High Quality and Efficient Seismic Acquisition for Frontier Deepwater Areas

摘要

The trend towards frontier deepwater (FDW) exploration plays around the world creates new challengesrnfor seismic data acquisition, processing and interpretation. Technical challenges focus on the need forrnhigh-quality seismic data to allow good understanding of geology from seafloor to target - so as well asrnproviding an image of the drilling targets, the seismic survey is must deliver reliable information aboutrnthe overburden to mitigate drilling surprises. In addition, economic challenges reflect the need to acquirerndata over large areas in a cost-effective manner, but without compromising data quality.rnThis paper reviews a new class of marine seismic technology that aims to address these previouslyrncontradictory demands. The technology is based on multimeasurement streamers that combine traditionalrnhydrophone (pressure) measurements of the seismic wavefield with densely spaced accelerometer measurementsrnthat derive the wavefield gradient in vertical and horizontal directions. These measurements arerncombined to perform dense seismic wavefield reconstruction. The results provide greater detail of thernseismic wavefield between the streamers and build a true 3D representation of the seismic wavefield thatrnis equally and finely sampled in all directions.rnIn the context of FDW exploration, this offers two main benefits. The first relates to the ability torngenerate high-resolution earth models of the overburden, where fine-scale isometric subsurface characterizationrncan help define safe and efficient well trajectories. This offers protection against noise and otherrnartefacts in the seismic data, which, despite the typical characteristics of ultra-deepwater environments,rnmay otherwise introduce interpretational uncertainty. It also mitigates inaccuracies and bias in the shallowrnvelocity model impacting the deeper earth model construction.rnSecondly, the ability to accurately reconstruct the seismic wavefield between streamers presentsrnoptions for acquiring data faster, more cost effectively, and with less operational and environmentalrnexposure. For example, using two- and three-boat operations to double or triple subsurface coverage withrna single recording vessel. A selection of examples using real and modelled data will be used to illustraternboth these key aspects.rnSuccessful seismic imaging for FDW means understanding the pathway to the target reservoir as muchrnas the target itself. A broad technology portfolio is required to provide integrated workflows, andrnmultimeasurement seismic acquisition can be a key component in the solution; addressing aspects ofrnenhanced resolution, wavefield sampling, and 3D deghosting, whilst also providing options to acquire datarnmore efficiently without compromising quality.