Drilling in Environmentally Sensitive Marine Areas in Western Australia: The Wonnich Appraisal Drilling Program Setting an Industry Example
Authors: Stejskal I.V. 
Published: October 2008

Abstract
The oil and gas industry is of major economic importance to the state of Western Australia. The majority of our activities are offshore, some occurring in shallow marine areas adjacent to sensitive resources such as coral reefs and mangroves. One of the main issues for the oil and gas industry and for Apache Energy in particular is continued access to marine acreage. Increasing public concern about the environmental protection of the coastal and marine environment has resulted in increased focus on the various users resulting in more stringent operating conditions and greater scrutiny on the issue of access of proposals to some areas. This paper outlines the framework used by the Government of Western Australia to manage offshore oil and gas exploration and development in a manner that permits these activities to take place in environmentally sensitive locations while providing protection for these areas. The Wonnich appraisal drilling program is presented as an example. This program consisted of two wells from the same surface location located one kilometre away from an area of high conservation value. A quantitative environmental risk assessment approach, research and monitoring, and oceanographic modelling were used to obtain government approval. Environmental approval took nearly two years but was instrumental in influencing government policy and in establishing precedents for the oil and gas industry operating in shallow marine areas.

Introduction
The oil and gas industry is of major economic and strategic importance to the Australian economy and is one of the fastest growing resource sectors. Australia is at present 70-75% self sufficient in petroleum liquid including LPG and 100% in its natural gas. Petroleum exports alone earned Australia $A4.5 billion in the 1996 - 1997 financial year. In order to maintain the present production and self sufficiency levels into the next century, it is estimated that the industry will need to commit to an ongoing structured program of exploration and production activity over the next decade. It is expected that most of the ongoing production and new discoveries will be in the offshore areas of northern Western Australia (Fig. 1), extending to the Timor Sea. Continued access to offshore fields, including those located in shallow marine areas, is of crucial importance for the Australian oil and gas industry in general, and particularly for Apache Energy (Apache) which explores and operates predominantly in tropical shallow water areas adjacent to islands and coral reefs.

Brief History of the Oil and Gas Industry in Western Australia
The first discovery of crude oil in Western Australia, albeit uncommercial, was onshore at Rough Range, North West Cape, in 1953. The State's first commercial field was on Barrow Island, one of the largest offshore islands, some 140 km off the coast of Western Australia: production commenced in 1967. The exploration of the open waters of the North West Shelf began in earnest in 1968 and resulted in major discoveries at North Rankin and Goodwyn and numerous other structures. While Bass Strait on the southeastern seaboard was once the major producer of petroleum for Australia, the North West Shelf of Western Australia has become Australia's leading oil and gas province.