After eight years in Buffalo and a couple of years in Idaho, my parents moved back to Wyoming at the end of 1970. They lived in Big Piney, a tiny cowtown with a lot of oil field activity around. There were some oil fields south by LaBarge which were more than a few decades old at that time.
Exploration wells had revealed the existence of a lot of tight sand formations containing natural gas shows in Sublette County, but the sands lacked permeability. The federal government proposed the Wagon Wheel project, which would have set off underground nuclear explosions to fracture the sands. This galvanized a well-organized opposition, to understate the firestorm of NIMBY rage, and the project did not happen in Wyoming. One nuclear fracturing (“frac”) job was tried in Colorado, rendering the gas, I am told, too radioactive to produce.
It was a standard practice for well operators to stimulate additional production by hydraulic fracturing (“frac-ing”) of the producing formation(s). I worked on a workover rig south of Big Piney in the winter of 1971, taking a hiatus from college. We were pulling the pumping rod and downhole pumps out of each well, setting a plug, shooting holes in the casing in a shallower formation (still 6,000 feet deep), and then “frac-ing” the new formation to stimulate a flow of gas. It worked pretty well. Several massive Halliburton pump trucks would be hooked to tanks of water mixed with gels, solvents and sand, and the mixture would be pumped under thousands of pounds of pressure into the formation. The pressure would force cracks in the rock and the sand would prop the cracks open. Sometimes marble-sized rocks were pumped into the cracks.
When the tanks were empty, the trucks would rig down and go back to Rock Springs. The next day we would swab out all of the water and oil and crud (rust, sand, oil residues) and hook the well up to produce gas. Then we would move the rig to the next well.
The Wyoming Oil and Gas Commission regulates this practice on state and private minerals; the Bureau of Land Management regulates it on federal minerals. It is required that the well be fully cased and that the casing be cemented at the surface and at every known water- bearing formation. In coalbed wells, the casing must be cemented from top to bottom with no gaps. The cement is logged using a gamma ray device that is run up and down the well bore. Great precautions are taken to assure that the fracture fluids remain in the target formation. (If there is gas in a formation, that is because there are relatively impermeable formations above and below it, so the frac fluids should remain in the target formation.) Frac-ing is expensive, so there are some incentives to do it correctly.
If there is an old well and the casing has rusted through, oil or gas can leak out. Operators will check to make sure the well bore is intact before spending money on a frac job. The regulators may require a mechanical integrity test before allowing a frac.
These precautions make it unlikely that a frac job will cause frac fluids to escape from the target formation, usually several thousand feet deep. Modern frac jobs involve high-tech equipment, including computers. If there is a leak somewhere, the equipment will immediately detect the drop in pressure. It is impossible for frac fluids to escape from a 5,000 to 8,000 foot deep formation and get into someone’s domestic water well 200 or 400 or 900 feet deep, unless there is another well bore nearby that was abandoned and not plugged. Even then, the frac operator will likely notice the excursion due to pressure changes. There are anecdotal reports of such events, but the industry trade groups maintain that there is no proven event of such contamination.
The new trend in the oil and gas business is to drill 6,000 to 7,000 feet down into impermeable shales, drill horizontal legs using new technology, and then perform large frac jobs in stages involving thousands of barrels of water per stage. The Bakken shale in North Dakota has new wells, after fracs, making 700 to 1300 barrels of oil per day. There are shales in Texas, Pennsylvania and elsewhere which are being developed using frac technology, frequently to produce gas.
Several environmental groups are trying to pass laws to have the EPA regulate frac-ing. They complain that the service companies conceal the identity of the gelling agents (the same gum as in chewing gum) and chemicals which stabilize the gel in high temperatures and high pressures, that the frac mixtures could contaminate domestic water supplies, and that the industry regulators are allowing operators to run wild. There was a piece on National Public Radio Science Friday in early January containing a lot of heat and very little enlightenment. There are many companies which try to keep their trade secrets from each other; this is not equivalent to concealing hazards from anyone.
I do not think that any of these complaints are well founded. A frac job can cost hundreds of thousands of dollars; most people won’t waste that kind of money without checking things out very carefully first.
If EPA were to put a moratorium on frac-ing while it spent several years developing new rules, this would kill the domestic oil and gas drilling industry.