The injection of waste water from petroleum extraction or gas extraction is not new in Drenthe. And injecting water into an empty gas field can certainly cause problems. That is, in a nutshell, what was heard during the well-attended information evening of Stop Afvalwater Schoonebeek (SAS).
About a hundred Schoonebeekers came to listen at ‘t Aole Gemientehoes.
It is meant as a counterpoint. Because at the information evening at the beginning of February of the Nederlandse Aardolie Maatschappij (NAM) and the Ministry of Economic Affairs and Climate (EZK), according to SAS, it was mainly explained why the injection of the waste water from oil extraction in an empty gas field under Schoonebeek is the best option.
So action group Stop Afvalwater Schoonebeek had gathered a number of experts who cracked critical notes about wastewater injection.
Earth scientist Sam Gerrits gets straight to the point. In Texas (US) between 1916 and 1926 in the Goose Creek field it became clear that mining can lead to subsidence and earthquakes. Gerrits shows two cards. In 1916 a narrow river can still be seen, in 1926 that stream was swallowed up in a larger delta. “Because of subsidence. The oil and gas extraction companies have known this for a hundred years.”
According to Gerrits, water was first injected into the Wilmington oil field (US) around 1950. “In 1961 there was a big earthquake caused by that water injection.”
Former NAM and Shell inspector Gerrit Wigger also argues that water injection, such as that which is to take place in an empty natural gas field at a depth of three kilometers below Schoonebeek, is not harmless. A very technical story follows, but according to Wiggers, wastewater was already being put into empty gas fields in the 1990s via three wells in Schoonebeek, Dalen and Coevorden. “There was even a whole program set up for it.”
“The NAM also does not know what happens to that water in the deep subsurface. There was an earthquake in the Dalerveld, possibly due to the water injection.” According to Wiggers, nothing has been done with the experience gained at that time and the mistakes that were made. Excellent material for doing better now, says Wiggers.
Wigger argues for the reuse of the water in the oil field. But if you still want to inject it into an empty gas field: “Gas can be compressed, water cannot. If you inject water into an almost empty gas field from above under high pressure, that gas field ‘erods’. Hollow spaces, salt creep (salt that liquid wants to go to the cavities), so subsidence or earthquakes are to be expected.”
According to Wigger, injecting from above has another disadvantage: it will ‘rain’ in the gas field. The water takes the salt crystals with it on its way down. Where the salt crystals disappear, the ‘pores’ in the rock become larger, with the risk of soil movement. “If you still want to inject, do it at the bottom of a gas field. Below the gas-water contact.”
Henk Steggink of Stop Afvalwater Twente (SAT) calls on the Schoonebekers to be critical of the information from the NAM. Steggink lists a whole series of things that were presented differently by NAM than they were in practice. “The wastewater would be injected at three kilometers into empty gas fields, which was more than one kilometer away.”
“The Germans have been doing this for years, said the NAM. True, but they feed the waste water back into the oil field and not into an empty gas field.”
“The NAM always talks about a very small amount of my building aids, a few per mille. But they only count the anti-rust agents and not the other chemicals. If you do that, you arrive at 7 percent of chemistry that goes with the soil in.”
Steggink lists a number of problems with eleven old gas extraction wells that were used for water injection. From a pit where half of the iron pipes have corroded away to a pit where there has been a leak for four years. According to the NAM, it did not leak, says Steggink, because the cement layer around the outer tube was still intact. “In the end, two wells remained that are usable.”
Jenneke Ensink of SAS is satisfied with the turnout. She is proud of the “group of volunteers who manage to draw a full house without a bag of money from EZK and NAM”. According to her, there were also Schoonebekers in the room who actually do not have much against the plans of the NAM, but “whose eyes have opened tonight”.
On May 16, SAS will hold a second information evening, which will include director Reinder Hoekstra of the Drenthe Environmental Federation. Hoekstra questions oil extraction. He also questions NAM’s plan to use electric boilers on green energy to generate steam for oil extraction. The NAM wants this to get rid of natural gas and CO2 emissions. “But then you start extracting fossil fuel with sustainable green electricity,” says Henk Vredeveld of SAS.