f Time-lapse seismic provides key constraints to dynamic models

Time-lapse seismic is one of the few technologies that provides a full-field areal picture of what is happening in the subsurface and is routinely used to update static and dynamic models. This is a mature technology in some parts of the world (marine + high porosity) and progress is continually made in more difficult areas (on-shore, HPHT, near infrastructure, lower porosity). Under the right conditions, time-lapse seismic is a proven method to detect and image differences due to changed fluid saturation and pore pressure inside the reservoir and deformations such as those related to reservoir compaction outside the reservoir. This capability often provides information on: (i) the progress of an injected fluid front, (ii) the ingress of an aquifer, (iii) the expansion of a gas cap, (iv) gas evolved due to depletion below bubble point, and (v) the distribution of reservoir compaction. The areal and vertical resolution of this information is typically at the scale of tens of meters. This technology addresses important uncertainties in our knowledge of reservoir connectivity and heterogeneity.