Further uses of SWIM
Shallow hazard identification and multiple removal throughout the seismic section are other benefits of using SWIM. It is a highly flexible solution that can be used on OBN data, such as PGS Optoseis.
Using SWIM With Non-GeoStreamer Data
SWIM imaging principles can also be applied to Ocean Bottom Sensor (OBS) surveys using reciprocity turning the traditional dense source grid of OBS surveys into a set of very dense ‘virtual’ receiver locations. By doing to so, the image and illumination of the subsurface can be enlarged to the area covered by the source grid.
Depth imaging slices in the shallow subsurface provided using primary reflections only (left) and using SWIM (right) for a deepwater PRM pilot in the Campos Basin, Brazil. Note the significant improvement in subsurface coverage using SWIM. Data: Petrobras
By invoking simplifying assumptions about the sea surface shape and its reflective properties, SWIM can also be applied to traditional hydrophone-only data.
Using Multiples to Remove Multiples Throughout the Section
SWIM enables the generation of detailed shallow overburden images that are a requirement for some data-driven 3D SRME multiple removal methods. Shallow imaging is vital for those 3-D surface related multiple modeling demultiple techniques that utilize a priori reflectivity information. Using SWIM enables a continuous shallow seismic reflectivity cube, facilitating the creation a more accurate 3-D multiple model.
Through improved shallow imaging in shallow-water scenarios SWIM allows for the prediction of multiples from not only the seafloor but also from layers below the seafloor (top image). This leads to the accurate removal of unwanted multiples deeper in the section. The left image highlights locations where shallow multiple energy is not predicted when using primary only imaging for the a priori reflectivity cube. A complete multiple image is shown on the right which is produced using SWIM to predict seafloor and near-surface multiples. Data: Wintershall.
Reducing Drilling Risk
Accurate imaging of the overburden using SWIM provides high resolution images suitable for shallow hazard work, helping to mitigate drilling risks. Channels and structures that can cause a borehole to collapse can be identified as well as shallow gas targets that could cause a blowout.