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Understanding the subsurface is critical to the needs of the E&P industry for minimising risk and maximising subsurface recovery.

S-Cube launches in 2015 to advance data-driven automated earth model building (FWI) from raw exploration seismic data.

Its inception comes at a point when wave equation PDE constrained optimisation becomes computationally feasible in 3D and proven with field demonstrations utilising data from ocean bottom seismic experiments.

The first major anisotropic application of FWI takes place optimising a velocity model with a shallow gas accumulation using a data feed from a North Sea ocean-bottom seismic survey.

The left column shows the existing model with a manually inserted low velocity zone to approximate the gas accumulation. The right column shows the iterated model optimised by fitting predicted to observed data automatically capturing the gas charged interbedded layers and faults in the low velocity zone.

Vertical slice through existing model

Vertical slice through existing model

Vertical slice through iterated model

Vertical slice through iterated model

Aerial view through existing model

Aerial view through existing model

Aerial view through iterated model

Aerial view through iterated model

What happens if we eliminate the low velocity zone from the starting model completely? The gas cloud is detected but the model iterates to a local minimum from which it cannot recover. 

Vertical view through model without any evidence of low-velocity zone

Vertical view through model without any evidence of low-velocity zone

Vertical slice through intermediate model without AWI

Vertical slice through intermediate model without AWI

Vertical slice through final model without AWI

Vertical slice through final model without AWI

Aerial view through model without any evidence of low-velocity zone

Aerial view through model without any evidence of low-velocity zone

Aerial view through intermediate model without AWI

Aerial view through intermediate model without AWI

Aerial view through final model without AWI

Aerial view through final model without AWI

The wider applicability of the technique is still limited at this stage given reliance on a-priori knowledge of the target, i.e. an accurate starting model. S-Cube formed to specifically solve this through restructuring of the optimisation cost function.

S-Cube reformulates the cost function of PDE constrained velocity optimisation with matching filters to overcome cycle skipping.

S-Cube formulates Adaptive Waveform Inversion (AWITMusing a convolutional filter mapping the observed data to the forward modelled data and varies the model to send the non zero lag filter coefficients to zero. 

This solves a long standing theoretical problem in waveform inversion and AWITM wins industry breakthrough award at the EAGE 2015.

Repeating the previous example with the AWITM cost function changing nothing else gives successful recovery of the gas cloud. At which point conventional FWI can be applied to return to the previously obtained global minimum result.

Vertical view through model without any evidence of low-velocity zone

Vertical view through model without any evidence of low-velocity zone

Vertical view through intermediate model with AWI

Vertical view through intermediate model with AWI

Vertical view through intermediate model with AWI

Vertical view through intermediate model with AWI

Vertical view through intermediate model with AWI

Vertical view through intermediate model with AWI

Vertical view through intermediate model with AWI

Vertical view through intermediate model with AWI

Aerial view through model without any evidence of low-velocity zone

Aerial view through model without any evidence of low-velocity zone

Aerial view through intermediate model with AWI

Aerial view through intermediate model with AWI

Aerial view through intermediate model with AWI

Aerial view through intermediate model with AWI

Aerial view through intermediate model with AWI

Aerial view through intermediate model with AWI

Aerial view through intermediate model with AWI

Aerial view through intermediate model with AWI

Vertical view through final model with AWI

Vertical view through final model with AWI

Vertical view through tomography model

Vertical view through tomography model

Aerial view through final model with AWI

Aerial view through final model with AWI

Aerial view through tomography model

Aerial view through tomography model

S-Cube signs AWITM software licensing contracts with Equinor and Woodside.

The application of AWITM directly leads to pre drill prediction of gas bearing formation offshore Myanmar. The prediction confirmed by sonic log when subsequently drilled. 

Vertical slice through featureless starting model

Vertical slice through featureless starting model

Vertical slice through XWI with AWI model

Vertical slice through XWI with AWI model

Increased reflection sensitivity = Deeper model updates

Reflection Waveform Inversion (RWI) specifically targeting the deepest penetrating energy in the survey is added to the XWITM toolkit.

Starting model

Starting model

Stage 1 - AWI

Stage 1 - AWI

Stage 2 - RWI

Stage 2 - RWI

Final XWI model

Final XWI model

FWI only model

FWI only model

On the left is the final result using XWITM toolkit which had the closest agreement with true model out of all industry contestants. On the right is the equivalent result using FWI by itself with spurious velocity values below diving wave zone.

In 2018 S-Cube develops and launches the XWITM Pay As You Go cloud user model hosted on AWS 

S-Cube is on a journey. It's not yet reached its destination but currently has an industry leading product and with AWS it is positioned for accelerated growth.
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