Calibration of a Weak 4D Seismic Signal for Fluid Pressure Assessement

Time lapse (4D) seismic monitoring technology is now a proven tool to monitor fluid movement and/or pressure changes and to distinguish between drained and undrained portions of a reservoir. Its ultimate goal is to quantitatively improve reservoir models, particularly their predictive capability.

Calibrating the 4D signal at the well with information obtained from production data is essential for it to be used quantitatively. In this paper, we present the application of a model-based inversion method to estimate the changes of elastic parameters in the reservoir due to production at the well.

The scheme used in the study is based on the observation that the production flow is driven by the “dynamic properties”. of layers, and therefore a layered model should be used to parameterize the inversion. To discriminate between possible physical phenomena connected with production (depletion or injection), we also need to use a petroelastic model.

We present results on a real data example on a 4D calibration of a turbidites field. The methodology was applied for a standard case and, more originally, to help interpreting an unexpected weak 4D signature.