1. FORCE abstract for “"New opportunities for monitoring the dynamic processes in the reservoir"”
Seismic to simulator workflow for time-lapse fluid predictions
Stig-Arne Kristoffersen, Ødegaard Norge A/S
Dave Davies Odegaard UK Ltd.
Klaus Bolding Rasmussen Ødegaard A/S
A circular workflow unites seismic surveys through seismic inversion with modelling of the
subsurface (static and dynamic) from the reservoir simulator such that acoustic
impedance and Poisson’s ratio derived from the seismic data and reservoir simulator are
directly comparable and interpretable in relation to rock properties and saturation.
Seismic inversion techniques provide calibrated difference volumes for time-lapse 3D and
allow legacy datasets to be used with maximum effectiveness. Pre-stack inversion
furthermore allows time-lapse quantified lithology and fluid predictions to be carried out.
This approach leads to fast, in-expensive and high quality 4D results, which utilize all
datasets acquired, and promises compression of the cycle time for 4D studies.
Using a new implementation of Ødegaard’s seismic inversion algorithm that includes the
4D expectations as a soft constraint all vintages of seismic data and all angle/offset
stacks of each vintage are inverted simultaneously. This enhances the signal-to-noise
ratio of the 4D observations and the resolution can also be demonstrated to increase with
the number of time-lapse surveys submitted to the inversion algorithm. The direct output
of the seismic inversion process is acoustic impedance, Poisson’s ratio and density,
which can be used to predict lithology and fluids and evaluate changes in saturation.
The saturation chances may be compared to the reservoir simulator predictions. A rock
properties model is developed and used to convert matrix, porosity, saturation and
pressure information from the reservoir simulator to acoustic impedance and Poisson’s
ratio.
Production
Data
Prior model
for changes
Dynamic
Model
Rock Physics
model
Changes in
Acoustic Impedance
Poisson’s ratio
ISIS
Seismic Simultaneous
Inversion
Rock Physics
model
Reservoir
Simulator
Changes in
Acoustic Impedance
Poisson’s ratio
Changes
in Saturation
and Pressure
Seismic 1
Seismic 2
Seismic 3
Changes
in Saturation
and Pressure
Static Model
Base Elastic Time/Depth Information
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