Abstract: A system of monitoring the fluid contents of a petroleum reservoir, wherein a reservoir model is employed to predict the fluid flow in the reservoir, includes a check on the reservoir model by comparison of synthetic seismograms with the observed seismic data. If the synthetic output predicted by the model agrees with the observed seismic data, then it is assumed that the reservoir is being properly worked. If not then the reservoir model, in particular its reservoir description, is updated until it predicts the observed seismic response. The seismic survey may be periodically repeated during the productive life of the reservoir and the technique used to update the reservoir model so as to ensure that the revised reservoir description predicts the observed changes in the seismic data and hence reflects the current status of fluid saturations. Implementation of this invention results in more efficient reservoir management.

Abstract: A processing method is disclosed for marine seismic surveying which utilizes two vertically spaced marine streamers each having a plurality of seismic detectors contained therein. A seismic energy source positioned at or near the surface of a body of water is utilized to generate seismic waves which propagate into earth formations below the water and reflect back up to be detected at each streamer. Seismic waves also reflect from the water/air interface back down toward the streamers and must be separated from the upgoing seismic waves to enhance the accuracy of the resultant trace. The seismic waves detected at two selected vertically displaced seismic detectors are combined to form a sum signal which is then combined with a scaled time integral of a difference signal to form a resultant signal which preserves either the upgoing or downgoing seismic waves.

Abstract: A marine seismic reflection prospecting system attenuates coherent noise through reinforcement of primary reflection data by the addition of corrected ghost reflection data. The system includes a seismic energy source, a detector, a wavefield separator, a time-shift element, and an element for generating an output signal representative of an additive linear combination of time-aligned primary and ghost signal components. The system's output is suitable for further pre-stack processing, e.g., NMO correction.