Summary
The Rigzone Newsletter quoted a report by Dave Michaels of McClatchy-Tribune Information Services of June 5 on proposed legislation that would increase the cost of drilling shale gas wells in the Barnett trend of the Forth Worth basin. Environmental groups are lobbying the Democratic Congress to make new regulations that would affect the hydraulic fracture completion technique now in use. Without hydraulic fracturing followed by proppant insertion, Barnett shale wells and those in other shale plays would be marginal or even non-commercial. The current technique is exempt from the federal Safe Drinking Water Act. Next week, Democratic lawmakers will introduce legislation which will require companies to report chemicals used in the injection water that is fundamental to the process. Residents in rural areas near Forth Worth have worried that oil field chemicals could invade their potable water wells. An Environmental Protection Agency study of 2004 found no threat to drinking water.
Analysis
Most, if not all potable water aquifers exist at relatively shallow depths. The Texas Railroad Commission is keenly aware of the need to protect near-surface water aquifers. They have the necessary information to locate and identify such formations. The commission publishes regulations which insure that surface casing strings are set at satisfactory depths. Further, all surface strings must be cemented back to the surface. If cement returns are not seen in the cellar, a “top job” is performed to fill waterever void space remains between hole and casing. This effectively isolates and seals off the potable water formations. The Commission exerts extra vigilance in populated areas. Formations which contain the shale gas are deep. Several thousand feet of sediments separate the shoe of the surface pipe from the pay zone which will be fractured. Once the well is fractured, it is backflowed to the surface and most of the fracturing fluid is recovered in steel tanks. Remaining fracture fluid is then produced with the gas where it is separated as part of the gas gathering process. Thus the chance of fracture chemicals seeping into potable sands is remote. The Texas Railroad Commission, famously, sets the standards for drilling and completion practices around the country. Both the Corporation Commission in Oklahoma, the Division of Oil and Gas in California and other state regulatory bodies are equally vigilant. All of them have a common interest in protecting the public from any and all hazards posed by the drilling and completion of oil and gas wells. In Texas and in other states, strict regulations govern the abandonment of wells which no longer produce. Companies must follow prescribed abandonment rules and the Railroad Commission has the right to witness such abandonments. The Commission imposes a time limit on temporarily abandoned wells. The logic being that over time, casings and tubing strings deteriorate allowing potential contamination. It is true that no system of regulation is perfect. Just as blow outs, fires and crown accidents have caused oil field disasters, incidents of pollution have been recorded. Most such incidents in the past involved livestock sickened by drinking contaminated water from an improperly abandoned earthen pit. Farmers and ranchers are quick to seek redress when this happens and usually get it quickly. Nowadays, oil and gas companies have safety inspectors who visit well sites looking for improper practices that could lead to surface pollution. Abandoned well sites are carefully surveyed to make certain that they are non-polluting. When all of these safeguards are taken into consideration, it is questionable what, if any, impact new federal legislation would have other than add expense to the production of crude oil and natural gas.Coalbed methane is another story and, as a rule, different regulations are in force. Here the problem is that the coalbed seams are often submerged or drowned by fresh potable water at shallow depths. The gas wells have to be de-watered before commercial gas production can begin. This process can take weeks and sometimes months. Problems arising from de-watering should not be confused with potential chemical contamination.
