Abstract:Waterflooding,an effective means for improving oil recovery,are used in many oil fields all over the world. The waterflooding effect greatly depends on the monitoring of waterflooding. The possibility of seismically monitoring the waterflooding in thin interbed reservoir is analysed by making forward modeling with the use of Gassmann equation. Analysis result says that sand porosity is a key to successful or failing monitoring of waterflooding,higher sandstone porosity leading to better seismic monitoring of waterflooding. The modeling analysis of different sand-shale interbeds shows that when the porosity and total thickness of sandstone are high enough,it is possible for us to achieve seismic monitoring of waterflooding. The authors found from seismic responds that in the case of constant porosity,waterflooding uplifts reflection legs,and that the uplift amount has much to do with the total thickness of sand layers in interbedded series but has nothing to do with the total thickness of the interbedded series,bigger thickness of waterflooded sand layerscausing more obvious uplift of reflection legs,with abno}'}nal amplitude in this case. Thaws,the forward modeling result helps reservoir engineer to determine waterfloodin} extent and to know qualitatively or quantitatively the location,advancedirectiori and advance velocity of waterfront.