Writing and Publications

U.S. Regulatory Considerations in the Application of Slurry Fracture Injection for Oil Field Waste Disposal

Sipple-Srinivasan , M ., Prepared for International Petroleum Environmental Conference (IPEC) '98 , Albuquerque, N.M., October 20-23, 1998

Abstract

The principal directive of the Federal Underground Injection Control (UIC) program, authorized by the Safe Drinking Water Act of 1974, is to protect underground sources of drinking water (USDWs) from contamination resulting from the injection of fluids into subsurface geologic formations. The UIC program regulates injection fluids in five classes of wells; Class II wells being for injection of fluids associated with the exploration and production of oil and gas. In 1988 the Environmental Protection Agency issued a regulatory determination stating that E&P wastes, being generally lower in toxicity than other wastes regulated under RCRA, should be exempt from RCRA Subtitle C regulations. Oil field wastes are consequently designated as non-hazardous material under Federal regulations and can be injected into Class II wells. Regulatory oversight for disposal into these wells has been delegated largely to individual States (Primacy States), with the USEPA administering the UIC program in the remaining States (Direct Implementation States).

Disposal of oil field waste into Class II wells through high pressure injection of slurried waste material into deep geologic formations has been successfully implemented in Alaska, the Gulf of Mexico, California, the North Sea, and Canada1-6. The method of Slurry Fracture Injection (SFIä) provides an environmentally sound and permanent disposal solution for terminal oilfield wastes where the alternative remedial options of landfills, road spreading, thermal treatment, and separation techniques fall short. Waste injection with this method results in minimal impact to surface land use, and reduced long-term liability to the operator. Current State regulations generally have some provision for new technologies to be approved. Injection pressures in SFI exceed the formation parting pressures and result in large volumes of waste material being deposited into disposal formations. Although individual State regulations vary, injecting above fracture pressure is often expressly prohibited. At issue is the security of proximal USDWs, and the containment of fractures, and consequently waste material, within the target formation. To minimize the potential for fracture propagation into confining zones adjacent to USDWs, an acceptable monitoring and analysis program capable of effectively tracking formation response to the SFI process must be designed.

For a complete copy of this article, click here to initiate download.