Engineering geophysics is helping to manage uncertainty in project risk reduction
The hydrocarbon exploration sector has long appreciated that geophysics can help manage significant uncertainty associated with exploration deep in the world’s sedimentary basins. With shelf and deepwater drilling running into tens to hundreds of millions of dollars, few developers would likely be comfortable with a drill-it-and-see approach.
Some of the success of this sector has arisen from the accelerated integration of geological, geophysical and engineering disciplines leading to better and more cost-effective investigation strategies: better data, better decisions and, ultimately, improved risk reduction.
As engineering geophysicists, our discipline has an equivalent role to play in helping geotechnical engineers better manage uncertainty associated with more modest depths.
“There is a need to accelerate the transfer of exploration technologies to the geotechnical sector and to make available some of the significant recent R&D advances from the academic sector”
Traditionally, site characterisation has relied upon preexisting site records, geotechnical drilling, sampling and laboratory analyses. Geological variation frequently does not conform to a regular prescribed borehole programme.
Modern geophysical techniques appropriately phased as part of an integrated investigation (usually early) can interpolate between invasive sampling
locations, but, critically, can also be used to optimise the design and increase the value from an intrusive investigation programme.
Early-phase geophysics could allow a wider spacing of subsurface investigations to be adopted where ground conditions appear to be relatively uniform, and provide justification for more closely spaced, targeted intrusive investigations where ground conditions are indicated to be complex and critical.
Often an integrated geophysical and geotechnical programme will provide significant additional site characterisation information at no greater cost and in less time than a traditional “boreholes only” programme.
There is a need to accelerate the transfer of exploration technologies to the geotechnical sector and to make available some of the significant recent R&D advances from the academic sector.
Of course, it would be preferred if these were components of a two-way process and it is believed that there is enthusiasm within the geotechnical community to understand the state-of-the-art in shallow geophysical investigation. The recent Near Surface conference in Paris showcased a number of advances in near surface investigation with technical sessions dedicated to civil and geotechnical engineering, geohazards, glacial environments, waste storage and hydrogeological problems.
As with the oil and gas sector parallel, in the challenging field of shallow geotechnical investigations, we might all need to be multidisciplinary explorationists to some degree - with a common focus on managing subsurface uncertainty and effectively reducing project risk.