Most new industries are first operated under manual control, and only as they mature do they start applying automatic controls and optimization. Fracking is no exception, and as it approaches maturity, it also is beginning to take advantage of automation. In this article, I will discuss some areas where automation could improve the safety of this industry, including methane recovery and operational reliability.
In the process of fracking, high-pressure water mixed with chemicals and sand is injected into layers of shale rocks deep under ground, which fracture under this pressure and release the gas and oil they contain. In 2005, Congress passed legislation prohibiting the federal government from regulating this industry and allowing it to not disclose what chemicals are being injected into the ground. This unregulated operation continued for a decade because of the argument that these processes were "proprietary," as they require unique machinery capable of driving the fluid down more than a mile, and also require a lot of science to calculate the exact mixtures of water, chemicals and sand required to crack the tiny fissures in the rock.
After many years, federal regulations are now being introduced, at least for the 100,000 fracking and regular oil and gas wells that are located on public lands. As of now, the states will still maintain jurisdiction over the wells drilled on private land. We do not accurately know their total number, but we do know that about one million unregulated wells have already been abandoned, and of those some 200,000 have never even been plugged.
See also: Controls for drilling oil and gas wells
One of the reasons why such large numbers are abandoned is the high depletion rate of their production. The "staying power" of these wells is short. In just the first year of operation, the production can drop 50% (see this report from Bloomberg Business). Therefore, in order to maintain or increase the total national production, the drilling of new wells is needed continuously.
Federal regulations that are just coming into effect cover several areas of fracking operation where protection of public safety is involved. Here and in future articles, I discuss these areas one at a time and also describe how process control and automation can and should be used to reach these goals. I particularly focus on the potential of automation for monitoring the types of toxic chemicals and their escape or leaking into ground and surface waters.
Are fracking fluids toxic?
Fracking fluids contain "proppants," such as sand, water and a large number of chemicals, that serve to keep the fractures in the shale open. In the past, the identity of these chemicals was not disclosed by their suppliers like Halliburton who considered that information proprietary (Figure 1).
Samples from well blowouts and fluid pits in Colorado, Wyoming and New Mexico have shown that the fracking fluids contain more than 100 different kinds of chemicals, some of them having adverse side effects including brain damage, birth defects and cancer. In other locations, heavy metals, salts (bromides, chlorides), acetone, radionuclide isotopes (strontium, barium), arsenic and volatile substances (methane, benzene, alcohol, toluene, phenol, ethylene glycol) were found in the fracking fluids.
Benzene causes cancer and bone marrow failure; lead damages the nervous system and causes brain disorders; ethylene glycol (antifreeze) can cause death; methanol is highly toxic; boric acid causes kidney damage; 2-butoxyethanol causes hemolysis (destruction of blood cells). Whatever chemicals the fracking fluids contain, they can end up in the ground water and the drinking water supplies through ground penetration or due to leaks in the piping or in the lining of the "frack ponds."
We have all heard arguments that "we put a lot worse stuff in our food, our yard and garden" than the fracking chemicals. This is true. Yet, we should still be more careful in protecting our drinking water supplies. The new federal regulations will require disclosure of the identity of the fracking chemicals and the methods used to prevent their release during fracking, storage in lined surface pits or disposal in ways such as injection into dry deep wells, which can and did cause minor earthquakes. Some consider this reinjection desirable to rebalance the underground pressures, because without that, ground movement (minor earthquakes) might result; others argue that it is this practice itself that can cause earthquakes.