The Coochilara Prospect is an anticlinal play in the Tenappera Trough of the Cooper Basin. Simple anticlinal closure defines the prospective structures at both lower Cretaceous and top of Permian levels. However, partially fault-sealed closure is required at the lower Patchawarra Formation and deeper Permian levels if potential accumulations of petroleum are to be large enough to be economic. Mapped maximum vertical closure is 120 feet at lower Patchawarra levels, while all closure on the pre-Permian sediments is fault-controlled. Coochilara has 2120 feet of Permian section which contains 1500 feet of prospective sediments of the Toolachee and Patchawarra Formations. A total Net Effective Pay of 170 feet is predicted for these formations. The Mooga Sandstone and Epsilon Formation are secondary objectives. The nearest wells to Coochilara are Dullingari 2, lying 9 km to the north, and Toolachee 2 which is 11 km south-west. Dullingari 2, located within the Burke-Dullingari Gas Field, has gas reserves in the Toolachee and Patchawarra Formations. Toolachee 2 is not a producing well, but is part of the Toolachee anticlinal trend which includes the Toolachee Gas Field. Producing wells in this field have encountered gas in formations all of which are early Permian in age. Major fault systems separate the Coochilara Prospect from the Burke-Dullingari Field to the north, and the Toolachee Field to the west and south. Correlation of the stratigraphic units from known ties to wells, to the prospect, are based on seismic reflection character and can be carried out at a high confidence level. The proposed well will provide information which may relate the stratigraphy of the prospect to that existing in either of the adjacent fields. The anticipated total depth of Coochilara 1 is 8900 feet, in pre-Permian sediments. Assuming a trap existence risk of 1, the maximum gas-in-place reserves are estimated to be 450 BCF. This well is proposed as part of the 1978 Independent Exploration Programme to be carried out on behalf of PASA. Delhi will be the operator. Ownership of any petroleum discovered will remain with the partners to the Toolachee area 50/30/10/10 Farmout agreement.