Research into shale gas extraction in North Brabant
Water companies are playing an active part in the ongoing discussions about shale gas extraction in the Netherlands; underground activities of this kind could have significant consequences for the availability of good drinking water. KWR has been conducting research, with and for the water companies, into the impact of shale gas extraction. Thus Brabant Water had KWR research what the impact would be in its own region, which contains not only the Boxtel and Haren shale gas “sweet spots”, but also 43 deep wells, 33 of which are abandoned. The research shows that any possible shale gas extraction would require extremely thorough monitoring to protect the quality of drinking water sources.
Are we going to drill for shale gas? The question is the subject of extensive discussions in the Netherlands, in which the drinking water companies are assuming their responsibilities and taking an active part. Any shale gas drilling would after all take place in the same underground where the companies abstract groundwater to produce drinking water. KWR is therefore conducting research, for instance, into the risks that shale gas extraction presents to the water provision, and into the requirements that possible drilling operations would in any event have to meet to ensure that drinking water sources – today and into the future – are not affected. This research, which is taking place within the water sector’s joint research programme (BTO), helps the water companies indicate the risks involved to the government, and advise it on the requirements that need in any event to be attached to any possible shale gas extraction licences. KWR is also part of the “Shale Gas and Water” basic research programme of the Netherlands Organisation for Scientific Research (NWO), together with various universities, research institutes and water companies.
“You want to keep shale gas extraction far away from existing wells”
Effective monitoring of old and new wells
Brabant possibly has extractable quantities of underground shale gas, particularly in the so-called “sweet spots” of Boxtel and Haren. Brabant Water therefore had KWR study the specific impact of possible damages caused by gas extraction in its region. What would happen, for example, with the region’s current 43 (“old”) wells, which were drilled for coal and hydrocarbon exploration? Many of these wells have since been closed and abandoned. Within the water sector there is no clear idea as to whether the wells currently represent a groundwater contamination risk, and whether shale gas extraction might bring with it new risks. KWR’s research shows that the current risk is small: if the use of the subsurface remains unchanged, the probability of the movement of gasses or liquids is small. But new activities in the deep subsurface in the vicinity of the sealed wells would increase the risk. “That’s why you want to keep shale gas extraction far away from the existing wells,” says KWR researcher Gijsbert Cirkel. “Say, at a distance of one kilometre, both on the surface and deep underground. Also, for both the old and new wells, you’ll need standard monitoring of the drilled-through aquifer systems that contribute to the drinking water supply. You’ll then be able to signal any contamination in good time.”
Water demand in North Brabant
“This research gives us the arguments with which to press the Ministry of Economic Affairs to include good monitoring as part of any possible shale gas extraction licence,” says Hans Bousema, Senior Advisor, Strategy & Policy at Brabant Water. “But another aspect of shale gas extraction concerns us: What will happen to the demand for water, and what waste streams will be created? Shale gas operations require water, which then becomes wastewater. What will this mean for the availability of clean water in our region?” Scenario analyses show that, in the first 16 years, up to 1.35 million m³ of water would be required annually for drilling and (slick water) fracking for large-scale shale gas extraction in North Brabant. Over the subsequent 17 years, the figure would still be about 0.58 million m³ per year.
“The research gives us the arguments with which to press for good monitoring”
Keep a close eye on wastewater
Shale gas extraction also produces large quantities of wastewater, which is probably too saline to discharge into surface water or for WWTPs. Depending on the technique employed and the starting assumptions, the volume could exceed 35 million m3 over the entire production period. This wastewater also includes the so-called “formation water”, which rises through the ground during shale gas extraction operations. Under current regulations, this water may not be injected into the deep underground, so that the only options are extensive reuse and treatment. “But a residual stream always remains,” says Cirkel. “It could possibly be transported to the sea and discharged. The question, however, is whether that would be ecologically desirable.” There are still a few snags when it comes to the right treatment of the resulting wastewater – even if all the procedures are properly followed without incident. “Because of its composition, the released wastewater constitutes a possible threat to the environment and to groundwater and surface water, and thus to drinking water production,” says Bousema. “In the event of shale gas extraction, it is therefore important that a close eye be kept on how the operator deals with this waste stream. Leaks into the ground could be very damaging. On this front, too, shale gas extraction demands good monitoring.”
© 2018 KWR Watercycle Research Institute
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