Year

1980

Degree Name

Doctor of Philosophy

Department

Department of Geology

Abstract

The highly populated and industrialised areas of New South Wales are the "have nots" with respect to natural gas reserves but are one of the largest markets for natural gas in Australia. Natural gas supplies are brought to these areas by a 1300 km long pipeline from the Cooper Basin in the northeast corner of South Australia. The expanding natural gas market in New South Wales will require, in the next decades, guaranteed supplies even in the event of insufficient deliverability through the Moomba-Sydney Pipeline or cut-off of the pipeline. Subsurface storage of natural gas in natural reservoirs near the market area offers one solution for guaranteeing supplies to this increasing market.

Petroleum exploration wells drilled between 1910 and 1973 in the Sydney Basin near Sydney tested the petroleum potential of the Permian Nowra Sandstone, Muree Sandstone and Snapper Point Formation. The present petrological, wireline log, structural and reservoir engineering study of water-bearing arenites in these formations resulted in the delineation of seven potential natural reservoirs near Sydney, suitable for storage and retrieval of natural gas. The structures of these reservoirs include both faulted and unfaulted gently folded anticlines, and an irregular dome. The areal extent and vertical closure range from 1 to 45 km2 and 15 to 225 m respectively. The cap rocks to the seven reservoirs are Permian impermeable arenites, siltstone, claystone and shale beds of the Berry Formation, Mulbring Siltstone, Wandrawandian Siltstone, and Snapper Point Formation.

In spite of the growth of authigenic quartz, calcite, and siderite which has considerably reduced the primary intergranular porosity, the quantitative evaluation of wireline logs indicates the remaining average porosity for potential reservoirs in the Nowra and Muree Sandstone to be from 5.5 - 12.2 percent and from 5.4 - 6.8 percent in the Snapper ~oint Formation. Permeabilities to dry nitrogen gas for the Nowra and Muree Sandstone range from 1.0 to 23.4 millidarcies and for the Snapper Point Formation from 1.5 to 98.5 millidarcies.

A total potential storage capacity for the seven reservoirs is estimated to be 21 342 x 106m3 of natural gas.

Dural South Nowra Sandstone reservoir 8 878 x 10 6m3 of natural gas

East Maitland Muree Sandstone reservoir 4 994 x 10 6m3 of natural gas

Kurrajong Heights Snapper Point Formation reservoir 4 730 x 106m3 of natural gas

Kurrajong Heights Berry Formation - Nowra Sandstone 1 546 x 106m3 of natural gas reservoir

Mulgoa Nowra Sandstone reservoir 922 x 106m3 of natural gas

Stockyard Mountain Snapper Point Formation reservoir 180 x 106m3 of natural gas

Woronora Nowra Sandstone reservoir 92 x 106m3 of natural gas

Their respective deliverability potential ranges from 0.041 0.256 x 106m3 of natural gas per day per well.

The potential storage reservoirs delineated in this study are favourably situated to the New South Wales gas markets of Sydney Metropolitan Area (Dural South, Mulgoa and Kurrajong , Heights); Wollongong - Port Kembla and the South Coast (Woronora and Stockyard Mountain); and Newcastle - Hunter Valley (East Maitland). These reservoirs are also favourably situated relative to the existing pipelines: Moomba - Sydney (Wilton, 'City Gate'); Wilton, 'City Gate' - Wollongong, as well as to the proposed gas pipeline from Wilton, 'City Gate' to Newcastle.

Apart from their primary function as natural gas storage reservoirs for peak shaving and security of supply, they could also be used for storing gas manufactured. from coal.

Of the three alternatives (duplication of Moomba - Sydney gas pipeline, building of liquid natural gas plants or development of subsurface gas storage) for adequate supply of gas to the New South Wales market, it would appear that the development of subsurface storage in natural reservoirs would be by far the most economically viable.

Comments

Accompanying map can be consulted with the print copy of the thesis in the Archives Collection, call no. is 552.009944/1

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