time-Lapse (4D) Seismic

Time-lapse, or 4D seismic, is a technique used in geophysics to monitor changes in the subsurface over time by comparing seismic surveys conducted at different times over the same area. The "fourth dimension" refers to time, with the first three dimensions being the spatial coordinates (X, Y, Z) of traditional 3D seismic data. 

4D seismic is primarily used in reservoir management to track the movement of fluids, such as oil, gas, or water, within a reservoir as production progresses. By detecting changes in the seismic response between different survey times, geoscientists can identify areas where hydrocarbons are being drained, where fluid fronts are moving, or where reservoir pressure is changing. This information is crucial for optimizing production strategies, enhancing recovery, and managing reservoirs more effectively.

The key benefits of 4D seismic include the ability to make more informed decisions about well placement, injection strategies, and production management, ultimately leading to more efficient and sustainable hydrocarbon recovery. It also helps in identifying bypassed reserves, assessing the effectiveness of enhanced recovery techniques, and reducing the risk of drilling non-productive wells.