TIME-LAPSE SEISMIC GEOMETRIC REPEATABILITY AND RESERVOIR MANAGEMENT OF FIELD X (DEEP OFFSHORE NIGER DELTA)

3D Time-lapse (or 4D) seismic data, images the changes in the reservoir and/or the overburden caused by production. The assurance in interpreting seismic changes depends on good seismic repeatability in areas unaffected by production, driving ever-greater control over seismic acquisition parameters, Phil Christie, Ed Kragh, Stephen Pickering (2004). It offers the possibility of identifying the inter-well distribution of bypassed and untapped oil, of monitoring displacement heterogeneity, and of detecting uneven pressure depletion away from wells. If obtained, these detailed observations could be used to increase ultimate recovery, reduce production costs, and prevent surprises such as unexpected early water breakthrough, Waggoner J.R, Western Geophysical EAME (1998).

Two repeatability metrics, normalized root-mean-square error and predictability, have complementary sensitivities to conditions bordering on causes of data mis-match and are useful for monitoring both our ability to repeat seismic data acquisition and to guide the processing of the data volumes. Phil Christie, Ed Kragh, Stephen Pickering (2004).

The aim of this project is to increase the understanding within the academia and the oil and gas industry in Nigeria, the correlation between geometrical and seismic repeatabilities, thereby enabling better informed 4D seismic survey design, potential cost savings from such fit-for-purpose designs and a reduced risk of a failed time-lapse seismic project using Field X as a case study.

To achieve this aim, the following objectives were arrived at;

• The geometrical repeatability, represented by the sum of the source and receiver errors will be evaluated.
• Seismic repeatability, using NRMS and Predictability will also be calculated.
• These calculations will be based on simulated and real seismic data.