Marine Technology Reporter Blogs - cgg

During the production phase of a reservoir, natural phenomenon, such as movement of fluids, changes in pressure and stress in and around reservoirs occur. In high-pressure reservoirs, pressure depletion during production is associated with compaction within the reservoir causing stretching or extensional stresses in the overburden and underlying formation. This causes variation in velocities and formation thickness, which can be observed as 4D time shifts between successive vintages. Tracking the movements of fluids due to production, for example, gives valuable information about the depletion of a field, and can indicate areas of bypassed oil or gas.

Reverse time migration (RTM) is a powerful imaging tool. It has the ability to account for rapid spatial variations in the velocity model and to utilize all wavefront information, producing superior images of the most complex structures. This is why RTM is frequently used to interpret salt structures in regions known to have complex salt geometries like the Gulf of Mexico. With the application of recent advancements such as Vector Offset Output and 3D angle gathers, the imaging capability of RTM is enhanced even further. RTM is a pre-stack two-way wave equation depth migration, recognized as being able to produce superior pre-salt images compared to other migration algorithms such as Kirchhoff, control beam migration (CBM) or one-way wave equation migration.

Airborne geophysical surveying is a process of measuring the variation in several key physical or geochemical parameters of the Earth. The most important parameters measured are conductivity, magnetic susceptibility, density, and radioactive element concentration. Any change in the Earth's near-surface that causes a measurable change in these parameters presents a potential application for airborne geophysics. Since 2000 CGG has been offering high-end airborne survey capability through the global merger of the leading airborne geophysical survey companies, which then joined the CGG group in 2013. CGG’s new time-domain electromagnetic solution maps shallow to deep geology in one pass.