The decision whether to continue petroleum exploration of a sedimentary basin when only marginally attractive oil and gas discoveries have been made is a difficult one, which can be assisted by the application of an appropriate fluid flow model. The pertinency of the Tóth‐Freeze‐Witherspoon model has been proved in the western Canada sedimentary basin and is now applied to the less explored Surat basin. The Surat basin consists of a narrow north trending trough filled with Paleozoic strata overlain by a thick, broad cover of Mesozoic sedimentary rocks, the whole forming a topographic feature bounded on the north and east by the Great Dividing Range and drained toward the southwest by the Darling River system. Hydraulic head maps and cross sections indicate that hydrocarbon accumulations are associated with quasistagnant portions of discharge areas in which flow is vertical with respect to the bedding, the result being increased salinity of the formation waters caused by membrane filtration and consequently conditions more favorable for the disaccommodation and subsequent accumulation of hydrocarbons. Although the detailed delineation of favorable areas in the Surat basin is difficult with the data presently available, the concepts and approach applied in this paper may be of value to those seeking hydrocarbon accumulations in sedimentary basins throughout the world.