An international company asked us to revisit our technical due diligence on an oil field acquisition opportunity offshore China, which was previously considered too small to be commercially viable. Our client had access to additional data and technical work carried out by the operator, which increased the GRV making the asset viable.
Our client had updated their depth map of the oil field based on new work by the operator which used velocities from pre-stack depth migration (PSDM) seismic data, where the TWT had been adjusted to account for fault shadow effects. There was also an additional horizontal well which provided addition depth control. Our client was now keen to proceed with the acquisition and our challenge was to provide an additional technical perspective on the validity of this work.
Our approach was to go back to the basics of seismic interpretation and depth conversion. We noted the well data showed an increased velocity with depth, which hadn’t been factored in appropriately into the depth conversion.
We also noted some anomalous velocities had been introduced to the PSDM around the edges of the field, and this changed the TWT image. We later found out that these had been manually introduced, without the proper controls.
As a result, our views did not materially change from our earlier evaluation and it also meant that our client should re-consider their plans to proceed with the acquisition.
While this due diligence exercise was ongoing, the results of another appraisal well became available. It confirmed the issues we had noted with the PSDM and velocities and the estimated field size reverted to the smaller range we had carried earlier.
As a result, our client did not proceed with the acquisition.Back to previous page