Abstract

Three years experiences of solids disposal using Slurry Fracture Injection (SFI) are reviewed Seven separate projects in Saskatchewan and Alberta have provided an experience base in waste management using SFI. and a regulatory framework is evolving. The article addresses the technological and regulatory environment necessary for the safety operation of SFI to give the best possible environmental security and resource protection in the long-term.

The regulatory agencies involved in permitting SFI of non-hazardous oilfield wastes must assure that there are no long-term effects related to potable water contamination or degradation. surface land use impairment. or loss of current or potential future natural resources. The hest way to achieve these goals is first to establish a flexible yet appropriate set of guidelines which guarantee that applicants have carried out appropriate site. reservoir. well. and SF! process operations planning before a permit is issued. Thereafter. the major regulatory tasks are to maintain audit control of waste volumes. enforce a minimum monitoring level which will give a high confidence of waste containment in the target zone. assure that any near-by resources are not being impaired. and that only the permitted wastes are being injected. At a minimum. stream volumes. bottom-hole pressures. well integrity demonstration. independent proof of containment. and regular auditing and reporting requirements are suggested Over-regulation is to be avoided to allow SFI to take place under the most effective operating conditions.

Introduction

Slurry Fracture Injection (SFI) for the deliberate disposal of large quantities of waste sand was first tried by Mobil Canada in Saskatchewan at the Celtic Pilot northeast of Lloydminster in the period 1988–1990. In the period 1993–1997, a number of SFI operations have been permitted in Alberta and Saskatchewan to dispose oily sand, "slops", and produced or waste water. The technology is now widely understood, and a regulatory framework is evolving in Alberta to permit SFI projects to proceed in an environmentally secure manner to meet the goals of the regulatory bodies as well as the goals of the oil companies.

To understand the need for regulatory control and enforcement, it is necessary to understand the basic technological aspects of SFI, the arguments levied to justify its environmental security, and the capabilities of monitoring and analysis. This article will address these issues in terms of the geological structures and the industrial practices of Western Canada. Then, recommendations for a specific approach to regulatory management will be made and justified.

OILFIELD WASTE STREAMS

Large volumes of non-hazardous oilfield wastes (NOW) are produced during oil and gas exploration, drilling, production, and refining. Table 1 describes some typical NOW streams generated during oil and gas development, although some of the refinery streams may have high levels of-metals and other compounds which may result in a hazardous classification. The two largest NOW streams in Canada are produced water and sand from cold production of heavy oil. Most produced water is filtered and injected into disposal formations at pressures below natural fracture pressure. Cold production involves letting sand enter the wellbore during heavy oil production to increase production efficiency1.

This content is only available via PDF.
You can access this article if you purchase or spend a download.