#5 - EM Surveys - Are they just a commodity?

How many consulting companies or facility owners in Alberta are getting geophysical surveys conducted for their projects based solely on price? Or worst, having some junior employee with no real professional training or oversight collect data at a site because its cheap?

Let's review what an EM survey is and why its use without consultation with a professional might put your company at risk for unprofessional practice. For the purpose of this blog, the term geoscientist means a registered professional with a scope of practice that includes near-surface geophysics. I will also use the term geophysicist.

Why we use EM Surveys

EM or terrain conductivity surveys are commonly used in western Canada to map contamination resulting from the development, operation, or closure of hydrocarbon leases. Hydrocarbons from a well make money, water does not. At most well sites, fluid pumped to surface is some combination of hydrocarbons and salt water. This water is commonly called 'produced water'.

As an energy company looking to make it, handling and transporting produced water isn't going to make senior management nor the shareholders very happy. The best thing is to separate the produced water from the hydrocarbons at site and get rid of it. In the early years, produced water was separated on site and piped into ponds (flare pits or sumps) constructed on site or even through a pipe run out the backside of the lease. Later, small diameter pipelines from several wells would send the water to injection wells. This was acceptable as the water was re-introduced into the formation keeping the formation pressures high enough to promote further extraction of the hydrocarbons. These salt water pipes are known to fail, and releases are common. Produced water is never completely free of hydrocarbons, so often finding inorganic impact also means the possibility of hydrocarbon impacts.

How an EM Survey works

EM surveys work on the principle of electromagnetic induction. The instrument itself contains a battery, some electronics and two coils. A transmitter coil at the front and a receiving coil at the back. An electrical current is generated and is sent to the transmitting coil at the front. We know an electrical current generates a magnetic field that is 90 degrees to the direction of the current. If you can remember high school or first year physics, you may recall these lessons in electricity. A magnetic field will create (or induce) a secondary electrical field with any conductive body it interacts with. In this case, consider salt impacted soil as the conductive element. This secondary electrical field now within the conductive body creates its own magnetic field, which in turns, induces an electrical current in the receiving coil at the back of the instrument. That current is read by the instrument and voila! A terrain conductivity measurement is created.

The Geonics family of EM instruments are ubiquitous. Early models of the EM31 were first introduced around 1980 and they have been in use ever since. Current models are simple to use and require little training. The resulting data downloaded from these instruments are also in a simply X, Y, Z format (eastings, northings, terrain conductivity value). This data is easy to import into a contouring package and images like the one presented above are simple to produce. And since most environmental practitioners have looked at EM survey results since their very first project, may feel qualified to review and interpret the results. The offshoot of this is that many believe that there is little need to involve a Geoscientist/Geophysicist as part of this workflow.

For many then, EM surveys are simply a commodity in which the lowest bidder gets the work because regardless of the operator, the resulting data set should be similar. Thus, the work is awarded based on availability and costs. In essence, the EM survey is merely a commodity to be bought at the lowest possible price.

However....

In December 2008, APEGA released a short document entitled "Use of Geophysical Instruments in Near-Surface Investigations". The document describes in detail what activities in which a geophysicist (geoscientist) is required, may possibly not be required, and is not required. Below is a screen capture of the table from the document.

To summarize the table, any geophysics that is mapping anything below the water table, or mapping of any geological features is required to have a geophysicist consult on the project. Investigations in the vadose zone (unsaturated soils) or directly related to soils (think agricultural applications) and utility locating do not require a geophysicist.

The document concludes with the following warning concerning the "Required" column:

A person who considers undertaking any of these activities is strongly encouraged to involve a geophysicist. Choosing not to involve a geophysicist and being found to have performed the work in an unskilled manner could result in action being taken against such a person under the Engineering, Geological and Geophysical Professions Act or under another professional regulatory act where he person is register under such an act.

Jeneric cautions environmental practitioners that direct geophysical work and interpreting the results without at least consultation with a registered professional does put them and their companies at risk of unprofessional practice. While rare, professional malpractice has been known to occur.

Like many things in life, one gets what one pays for. Understand what your geophysical consultant or vendor is bringing to your project. A professional geophysicist with many years of expertise in western Canada, combined with a trained team of operators that collect a suitably dense grid of measurements should collect quality data resulting in a quality report. The report should also be signed with a professional stamp and a permit to practice stamp.

A well done geophysical survey brings value to the project, and protects the owner and consultant. So, the next time you need a geophysics survey, ask yourself and your team if it is worth the risk to treat these surveys as a commodity and look for the lowest price or is it worth paying a bit more for a better product that supports your project goals. If an EM survey is still just a commodity, don't be surprised if you didn't get what you wanted when the report arrives.