Abstract

Cuttings and other drilling waste injection through downhole fracturing started in the late 1980s and by the early 1990s, drill cuttings injection was being performed worldwide as an economically sound and environmentally safe long-term solution for drilling and production waste management. Although drill cuttings injection has become the preferred drilling waste management option in many parts of the world, each situation is different and the biggest hurdle in applying this technology for drilling and production waste management in some countries is waste injection permit application either because the regulatory agencies have not established any permitting requirements and application procedures or because the E&P operators are not familiar with the application process. Although different regions or countries have different permitting requirements, many of the requirements are essentially the same. This paper presents a review and analysis of worldwide drilling waste injection permitting requirements. Common permitting requirements are given with application procedure guidelines. The operators can use the guidelines to prepare their permitting application, while the regulatory agencies may use the review and guidelines as a reference for establishing or streamlining their own drill cuttings injection permit application requirements and procedures.

Introduction

Oil and gas exploration and production (E&P) operating companies are responsible for recycling, storing or disposing of drilling wastes in a safe and environmentally acceptable fashion, and in accordance with any regulation requirements. The principal waste product of the drilling process is oil-contaminated rock cuttings that result from the creation of the bore hole. These cuttings are a mixture of lithologies dependent upon the local stratigraphy and drilling muds. The drill cuttings are separated from the mixture of drill cuttings and drilling muds at the surface and are ultimately disposed of or, in some cases, recycled. Additional drilling wastes are oil-contaminated rainwater, wash water from flushing cuttings from shale shakers and any other non recyclable fluids. In response to increasing environmental concerns and legislative developments, these wastes must be managed in an environmentally friendly and economically sound manner. Current acceptable waste disposal schemes involve partial pre-treatment of both fluid and solid wastes to reduce the contamination before disposal. Tightening environmental legislation worldwide and operators' environmental policies are reducing options for disposal or are increasing discharge costs to the extent that discharge of drilling wastes may not be a future option.

Injection of oil-contaminated drill cuttings and associated wastes through hydraulic fracturing is attracting considerable attention as a cost-effective and environmentally friendly means of complying with environmental legislation and/or company policies concerning discharge of drilling waste. This is because:

  • Drill cuttings injection can achieve zero discharge.

  • There are no transportation risks or greenhouse gas emissions associated with transportation, as the generated wastes are processed and injected back into a subsurface formation at the location where they are generated.

  • There are no future clean-up liabilities once the disposal well is plugged.

  • The operator has total control over the waste management.

  • This waste management technology is not limited by location. It has been applied in many parts of the world and operational experience has proven that it is an environmentally safe long-term solution for E&P waste management.

  • It often has favorable economics.

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