Publication Name: The Cooper & Eromanga Basins Australia
Authors: J.S. Rodda and T.G. Paspaliaris
Date Published: June 1989
Number of Pages: 23
Reference Type: Book Section
Abstract:
The Tirrawarra and Moorari Oil Fields, discovered in 1970 and 1971 respectively, are located in the SouthAustralian portion of the Cooper Basin, with the Tirrawarra Field being the largest onshore Permian oil field in
Australia. Primary oil production from the two Fields commenced during 1983 from the low permeability Tirrawarra Sandstone reservoir. Enhanced oil recovery (EOR) operations were initiated in February 1984 with a
pilot gas injection (miscible flood) project in the Tirrawarra Field, and later expanded to the Moorari Field in
September 1984, to arrest the decline in productivity of individual wells being observed in both Fields under
primary depletion.
Following the encouraging results of this pilot project, the expanded pilot stage of the planned EOR scheme was initiated, with additional injection wells being added to the Tirrawarra Field in October 1985. Significant development has since taken place in the Tirrawarra Field towards achieving inverted seven spot injection patterns. As at January 1989, gas was being injected into five wells in the Tirrawarra Field and into one well in the Moorari Field. Injection was initiated using a mixture of the Tirrawarra Satellite solution gas, and non-associated
Patchawarra Formation separator gas, to defer the high facility costs associated with the use of an alternative
injection gas. However, following the proven success of the EOR scheme, an ethane trunkline was constructed from the Moomba Plant to the Tirrawarra Satellite Station doting 1986, and since April1987 the ethane stream (88.5 per cent pure ethane) being produced from the top of the de-ethaniser in the Moomba Plant has been used as the injection fluid. An extensive radioactive tracer injection program was initiated, with the injection of various radioisotopes into the gas injection wells. A detailed sampling program from surrounding pattern producers is underway in order to closely monitor the paths of injection gas breakthrough via tracer detection and changing composition profiles.