DEVELOPMENT OF THE WOODADA GAS FIELD

Abstract

The Woodada gas field was discovered in May 1980, when the Woodada 1 well flowed gas at a rate of seven million cubic feet per day from a carbonate unit within the Carynginia Formation of the onshore northern Perth Basin. Appraisal and development drilling has resulted in a total of 11 wells, of which seven have produced sales gas.

The reservoir is estimated to have contained initially at least forty four billion cubic feet of gas-in-place in the developed part. There is a prospective area to the south with similar potential.

The Woodada field is a combination structural/strati- graphic trap, where an up-dip lithology change effecting a permeability barrier seals the reservoir across a north plunging anticline. Porosity within the reservoir is secondary, with natural fractures often contributing to the production mechanism. The presence of fractures has required special attention to drilling and completion techniques. Gas production is significantly enhanced by acidization.

Pressure responses measured in or between wells combined with more than two years of production history have demonstrated that there is moveable gas in the fine voids of the matrix rock, as well as in the better developed secondary porosity system. Even where there is no substantial porosity in a well bore, it has been possible to achieve commercial production rates by acid stimulation.