Monitoring of Oil/Water Fronts by Direct Measurement

K. N. B. Dunlop, G. A. King, E. A. Breitenbach

Direct measurement of the position of reservoir fluids during production has great potential for improving recovery. It provides advance warning of changes in production behavior that may be used to prolong well life or to place new wells more effectively. A monitoring technique that locates moving reservoir fluids by taking the difference between successive seismic surveys is described.

Field measurements are provided by repeated surface seismic reflection surveys of limited extent. The seismic measurements are processed to minimize noise and to derive the difference between successive surveys. All acoustic, production, and reservoir data are then integrated by reservoir simulation to define fluid interfaces and volumes. The simulation model provides improved performance predictions.

Knowledge of fluid movement in the reservoir is a key to enhanced production management and determines the quality of performance predictions. Currently, wells provide most of the data available during production. However, fluid breakthrough at a well usually signals a decline in its production rate. Reliable advance knowledge of the locations of fluid interfaces away from wells would allow remedial actions to be taken, extending their economic life. This paper describes a monitoring technique using repeated seismic surveys which allows detection of saturation change at locations distant from wells. The seismic process has been validated in a field under waterflood. The results of the field trial are discussed and presented.

AAPG Search and Discovery Article #91022©1989 AAPG Annual Convention, April 23-26, 1989, San Antonio, Texas.