DRILLING FLUIDS AND THEIR ENVIRONMENTAL MANAGEMENT: THE INTRODUCTION OF AN ESTER OXYGEN-BASED FLUID

Abstract

An oxygen-based fluid (OBF) containing fish oil ester was introduced in October 1998 for the extended reach drilling campaign on the Goodwyn Alpha platform.

The introduction involved multiple discussions with the West Australian Department of Minerals and Energy (WADME) and adherence to the risk-based approach from both WADME and the Woodside Energy Ltd (WEL) policies and standards for well engineering operations.

The WEL approach to the introduction of the fluid was to address the issues associated with the use and discharge of the ester.

The issues included the development of a fluid system which was optimal for extended reach wells, engineering solutions to minimise the amount of fluid discharged, and gaining a better understanding of the environmental impact of the fluid to local conditions.

To minimise the volume discharged, the platform was refurbished including an upgrade to state-of-the-art solids removal equipment and modifications to the fluid system to ensure double discharge barriers.

Baker Hughes Inteq conducted an extensive development program of the ester fluid system, involving more than 5,000 man hours of laboratory work.

In conjuction with Curtin University of Technology, ecotoxicity testing was conducted to determine the acute impact on local species on the North West Shelf. A closed- bottle anaerobic biodegradation test was developed by Geotechnical Services to compare biodegradation rates of different fluids.

By minimising the volume discharged and evaluating the impact of the discharge on the marine environment, WEL has demonstrated a comprehensive risk-based approach for the introduction of an OBF to WEL's platform and mobile drilling operations.