4D Monitoring Using Gravity and Gravity Gradients

IG-6 4-D MONITORING USING GRAVITY AND GRAVITY GRADIENTS E.K. BIEGERT 1 and S. WITTE 2 Introduction 1 1 Shell International Exploration and Production Inc. 3737 Bellaire Boulevard Houston TX 77025 USA 2 Shell International Exploration and Production B.V. Gas-Fluid contacts within reservoirs have the potential to create large density contrasts that may produce gravity anomalies detectable by suitable sensitive gravimeters and gradiometers. In a time-lapse or 4-D mode these sensors may act either directly as monitors of reservoir performance or can be used as "triggers" to aid in choosing when an expensive 4-D seismic "snapshot" might be required. Gravity has