oa 4·0 SEISMIC: A POWERFUL NEW TECHNOLOGY FOR MONITORING STEAM MOVEMENTS IN DURI FIELD· CENTRAL SUMATRA

Repetitive (4-0) seismic surveys are able to monitor reservoir changes due to steam injection in Duri Field. Maps of reflection anomalies from the base of the injection interval show the spatial distribution in the 4-0 pattern can be made from seismic anomalies calibrated with the help of core and well temperature measurements. Some of the Duri oil reservoirs have minor gas saturation before steam injection due to pressure depletion, After steam injection, a high velocity annulus attributable to fluid pressures exceeding bubble point pressure is observed on themonitor data sets. Subsequent movement of this pressure front indicates areas of greatest permeability and is potential predictor of later thermal and steam front movements.