HRS 3D data — a fundamental change in site survey geohazard interpretation
Despite improvements in acquisition, processing and interpretation techniques over the last 30 years, it appears that our ability to unambiguously identify the presence of shallow gas has not improved at the same rate. The industry sets high standards and has endeavoured to raise these standards by issuing up-to-date guidelines for conducting drilling hazard site surveys. The most recent advances have been in the acquisition of HRS 3D and pseudo 3D data. Over the last three years, we have successfully acquired and processed nine HRS 3D datasets in the North Sea. There is an expected improvement in the quality of the data due to the enhanced horizontal resolution and the understanding of the geology which can be derived from the 3D perspective. However, what we did not expect to see was the degree to which anomalies indicative of the presence of shallow gas can be identified on the HRS 3D data but cannot be interpreted from the HRS 2D data. We believe that in certain situations this fundamentally alters the approach we should take in assessing shallow gas hazards from HRS 2D data alone.