Electro Seismic Survey Redefining Below Ground Exploration

In the pursuit of emissions reductions from combusting coal bed methane (CBM) and coal mine methane (CMM) under the UNFCCC clean development mechanism one needs a robust tool to locate the methane gas underground.

Finding such gas, was once a hit and miss affair, characterised by EITG South African Director of Operations Simon Baillieu, as a ‘visit to the casino’

Since environmentalists have become aware of practices such as ‘fracking’ and allegations of contamination of aquifers simply dropping a well without robust information has become increasingly unwise.

Recently EITG identified a tool that uses electro seismic technology simplifying the process of data gathering. The resulting processed data provides higher resolution and more detailed results. A suitable analogy is that of an MRI versus an X-ray. Sophisticated software and superior signal data replaces much of the effort that was previously involved in the investigative process whilst also achieving improved results.

The field data collection system consists of a trailer based rig with a weight drop machine. The sensor array is two probes located immediately adjacent to the rig. This simplified approach requires less staff of lower qualification to operate. Data collected can be batched or immediately emailed via cellular data connection to base for processing. A large area can be surveyed quickly and cost effectively. Inserting the small light weight rig via helicopter or small tractor means minimal impact on the environment. Further, the procedure is unobtrusive with such a small environmental footprint, in most jurisdictions no formal consent from authorities is required to perform the survey. Surveys can be completed in sensitive areas with little or no environmental impact.

The resulting data is processed on computers using complex software algorithms that can finger print the underlying strata. These algorithms are highly configurable and can ‘learn’, further enhancing the results while all data processing is completed off site.

The underlying concept has been known since the 1950s and scientifically documented in the 1960s. It was and is still widely used for building foundation work in some countries and for locating water just below ground. Recent breakthroughs by engineers have enhanced the technology and it now provides data at depths up to 6km

The output provides 3D models that identify primary and secondary permeability of rock structures, the later via identifying horizontal fractures up to an angle of 30 degrees. The technology is so sensitive that it can be used to distinguish between fresh and saline aquifers.

As such this is an ideal tool for location likely sources of CBM and CMM in underground structures.

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2 Responses to Electro Seismic Survey Redefining Below Ground Exploration

  1. This seems a very bland & vague description of a geophysical technique. What is it exactly? is it seismic (sound waves) or EM (radio waves)? Electro-seismic does not make sense. In my experience, using geophysics for CBM delineation has delivered very little thus far. I am very sceptical of the claims above.

    • eitg says:

      The underlying concept has been known since the 1950 and scientifically documented in the 1960s. It was and is still widely used for building foundation work in some countries and for locating water just below ground. Recent breakthroughs have enhanced the technology and it now provides data at depths up to 6km.

      Work in Australia, Africa and the USA have proven the tool for use in identifying structures that potentially hold gas and differentiating them from other structures such as aquifers. Substantial mining operators are using the tool to meet exploration and environmental objectives.

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