Abstract：Before ninetieth last century the major oilfields in China were discovered using low-fold large-cell-size 3Dseismic or even 2Dseismic acquired by recording systems with the capacity of several hundred channels.Obviously these kinds of seismic data could neither satisfy the needs of reservoir monitoring nor be used as the baseline survey of the time lapse seismic.The reservoir monitoring and remaining oil prediction for these oilfields thus becomes a difficult subject.A heavy oilfield in Northeast China was chosen for the seismic reservoir monitoring study with no baseline survey available.Production of this oilfield started in 1997,and two monitor seismic surveys were acquired in 2009and 2011respectively.Obvious time lapse seismic difference which reflecting the reservoir change in the time period of two observations can be evaluated from the final processed results. But the reservoir changes before 2009could not be estimated.To solve the reservoir monitoring problem,reservoir structural interpretation and depositional interpretation of the 2009seismic,integrated reservoir modeling of seismic and well logs as well as reservoir simulation were carried out.And final 3.5Dseismic interpretation based on these studies gives us the reservoir monitoring results before 2009.Combining the 3.5Dseismic results and the time lapse seismic between 2009and 2011, reservoir changes was evaluated and remaining oil was predicted in despite of no baseline seismic measurement.The prediction is verified by the temperature measurement and production information in the field.
