APPLICATION OF TIME LAPSE (4-D) SEISMIC DATA IN LOCATING HYDROCARBON PROSPECTS IN UDAM FIELD, ONSHORE NIGER DELTA, NIGERIA

Abstract

Application of time-lapse seismic data in imaging the effect of production related changes and locating bypassed hydrocarbon prospects in Udam Field Onshore Niger delta has been undertaken. The study was carried out using suites of well logs, 3-D and time-lapse seismic data acquired at different vintages. The differences resulting from acquisition design and other non-production related variations were minimized between the surveys vie phase and time matching as well as shaping filter processes. The synthetic seismic model was derived to predict changes in the reservoir that basically result from gas injection. This production induced changes and other unknown hydrocarbon bearing intervals were revealed by the data slices created from the inverted base and monitor. The data slice of the inverted base along the HD reservoir intervals isolates the reservoir zones which are consistent with low values of instantaneous phase and frequency which are indication of hydrocarbon bearing sand. The produc tion induced changes and other unknown hydrocarbon bearing intervals away from the wells were successfully isolated using difference slice (Monitor- Base). The results showed very low instantaneous phase and frequency around the wells locations and hydrocarbon bearing sand intervals away from the current well positions. The difference slices showed anomalous increase in values of instantaneous phase and frequency at well locations which are indication of production related changes. The delineated sand beds in the southeastern and western parts of the field were believed to accommodate bypassed hydrocarbons.