The American Association of Petroleum Geologists, an international organization of over 30,000 earth scientists, supports scientifically designed, state-based environmental oversight of hydraulic fracturing treatments for those coalbed methane and other hydrocarbon wells that may occur near zones of potable water. Oversight must be based on the recognition that:
- Modern fracturing treatments have not been shown to damage the environment.
- Most hydraulic fracturing takes place in zones removed from drinking-water supplies.
- Although fracturing fluids vary widely, the commonly used ingredients are limited in toxicity and/or mobility in water.
The Association opposes blanket application of federally mandated controls, which create a time-consuming, onerous bureaucratic maze with little useful result. Federal legislation should be encouraged to provide for streamlined permitting of fracturing treatments.
Treatments carried out in isolation from fresh-water aquifers should be exempted entirely from Clean Water Act controls.
Permit procedures for fracturing within aquifer zones (mostly undertaken in support of methane production from coal beds) must be designed on a basin-by-basin and state-by-state basis. This permitting must bear in mind the wide variety of possible designs of safe fracture treatments, and the geologic relationships of reservoir beds and aquifers unique to each area.
Background
In 1999, the 11th Federal Circuit Court of Appeals seated in Atlanta issued a final ruling in the case of Legal Environmental Assistance Foundation (LEAF) v. Environmental Protection Agency, stating that the EPA must regulate hydraulic fracturing as an underground injection well [Underground Injection Control (UIC) Class II] under the Safe Drinking Water Act. Previously, the EPA had not regulated fracturing, since this process was not intended to inject fluids into formations, but rather to improve the properties of the reservoir. No state, up to now, has regulated fracturing as underground injection.
The decision did not differentiate between the coalbed methane wells that were the target of the suit, and all other oil and natural gas well fracturing, nor was it limited to one state, although it was specifically applied to Alabama.
Based on the appeals court ruling, the EPA threatened to remove Alabama's UIC supervisory role, since the state process did not cover fracturing programs.
On Jan. 19, 2000, the EPA published a final rule that allows the state to retain primacy of the Class II UIC program, if it regulates fracturing in compliance with the class. This implies, among other things, that federally certified drinking water will be used for fracturing. However, the extent to which these rules will be extended to other states and other fracturing treatments is unknown at present.
A legal response by LEAF also is still possible.
The details of this case will change during the coming months, but the general issue of the regulation of fracturing under the Safe Drinking Water Act is of substantial concern to the geological community.
Nature of Hydraulic Fracturing
Hydraulic fracturing is a process applied to boreholes to improve the ability of fluids (such as oil and gas) to flow to the hole and be recovered. The technique is often necessary to let the mineral owner or lessee produce hydrocarbons commercially.
Water (usually with additives) is pumped into the target reservoir rock at high pressure, causing the rock to fracture away from the hole. Sand or other grains, known as "proppant," are introduced in the fracture to keep it open, and help fluid to flow back to the hole. Nearly all of the injected fluid is then recovered during the time the well is flowed back to the surface. Some of the fluid coats the fractures, or is lost into the natural fracture network of the rock.
The fluids used in hydraulic fracturing vary from pure water to gummy gels. Pure "water-fracs" do not contain environmentally hazardous substances. Other frac treatments contain various substances to improve the fluid's flow characteristics and effectiveness in fracturing the rock formation. While some additives may not be suitable for treatments in active aquifers, most are not toxic. All fracture treatments are designed such that the fluids are limited to the hydrocarbon zone being treated.
Fracture treatments vary from small to large. Fluid volumes introduced range from a few hundred to over 100,000 gallons, and fractures may extend outward from the well for tens to over a thousand feet, and vertically over tens to hundreds of feet. The amount of unrecovered fluid is typically 10 to 50 percent of what was introduced, usually less than 30 percent.
Very few cases of lost fracturing fluid showing up in other wells have been reported. The Alabama case rested entirely on one or two claims of slight contamination in wells that have always yielded low-quality water. These wells were producing water directly from the coal seam that was the target of fracturing for coalbed methane production. Water wells in this area typically produce methane as an unwanted and potentially dangerous byproduct, regardless of hydraulic fracturing.
Geologic Controls on Environmental Hazard
Given the limited extent of fracturing due to hydraulic treatments, any application of these treatments more than a few hundred feet vertically separated from aquifers does not pose a threat to potable water. The effects of fracturing in the vicinity of aquifers depends on the interrelationship of the aquifers and the target gas reservoirs, the size of the fracturing treatments applied and the fluid content of the treatments. All of these factors vary for each geologic unit in each sedimentary basin.
Because of this local variability, any necessary regulations must be designed not at the national level, but in the individual states. The state regulatory authorities have the necessary knowledge of the local geology, environmental concerns and engineering practices.
Given the extremely small risk of environmental degradation attributable to hydraulic fracturing, and the economic necessity of these treatments for commercial hydrocarbon production, any regulation and permitting that may be required should be as streamlined as possible. In the case of coalbed methane production, where large numbers of wells may be drilled and produced, a state agency should produce blanket regulations based on best current practices in the region.
Permitting of wells following a blanket regulation should be a simple one-hour process.
Summary
Hydraulic fracturing of wells involves injection of a small volume of fluids, most of which is immediately recovered. Very little environmental damage, even in shallow coalbed methane areas, has ever been documented. Because of this, the federal and state governments should consider revising only legislation and regulation related to significant fresh-water aquifers. Any new regulations, preferably at the state level, should provide a streamlined oversight of fracture stimulation operations within aquifer zones.
Reading
This information was prepared and reviewed by certain scientific members of the Energy Minerals Division and by the Governmental Affairs Committee of the Division for Professional Affairs. Both are divisions of the American Association of Petroleum Geologists.