Time-lapse (4D) seismic is a tried and tested method to monitor fluid changes in a producing reservoir, but its effectiveness and reliability depend on the quality and repeatability of the surveys. It still has significant limitations when applied on land for monitoring some deep reservoirs (depth >1000 m) where production rates are low and many other factors are unfavorable for effective 4D acquisition, processing, and interpretation. Modern high-density, wide-azimuth, and multi-component data-acquisition techniques have resulted in a step change in reservoir imaging and fluid prediction; however, the absence of a baseline or equivalent data set hinders the utility of such good data for inferring reservoir changes and locating remaining or bypassed hydrocarbons.