OIL SHALE DEPOSITS

Gisborne Herald, Volume LXVIII, Issue 20525, 8 April 1941, Page 2

OIL SHALE DEPOSITS

f ‘.REPORT ON OREP.UKI } FURTHER DRILLING URGED ! 5 SCIENTISTS’ ESTIMATES i; i (! 'pf’cial to the HeraTd.) WELLINGTON, this day. >. The '-petrol shortage has again ?' brought into prominence the possibility of production from New ZcYt- • land's shale oil deposits. Those at Orcpuki, Southland, have been mined i and 14.0U0 tons treated, but Die works 5 were abandoned in 1903. Large-scale distillation tests show that on the average oil shale yields 43 gallons <>: : crude oil a ton, and also 2G.71b. of » ammonium sulphate. * The New Zealand Geological Survey has completed a report on the Orei puki deposits, and these investigations result in’a recommendation for further prospecting by drilling on sites ■, which have been, indicated. Because there is insufficient information for ; exact, estimates of the available oil « shale in the .Orcpuki area, the report < states 'that it is better to express l estimates in maximum and minimum figure:;, pending further prospecting. Four Areas Surveyed Four areas were surveyed closely. I outcrops being traced and estimates ;; made of probable thickness of the ! seams. These- methods suggest that p the total 1 probable maximum amount Of oil shale is .6,769,000 tons, but asfj sliming that, no extension of the shale f; , could be assumed without observed ‘ • outcrops, the report places the minimum quantity at 1,770.850 tons The wide limits between these estimates can, it is stated, only be reduced L 1 by prospecting the sites by drilling. ' ‘ The results o£ magnetic observations and geophysical surveys are given, and average crude oil production from Ordpuki is shown to be 38 gallonfe a ton, compared with a range of 48 to 160 from the New South Wales de- ! posits which are being worked. Cost of Production The most important factor in oil production from shale is that of mining, which the report estimates will cost 20s per ton at Orepuki, ,• v though- at Glen Davis, New South Wales, where conditions are superior, the cost is 15s per ton, and the actual , ... cost of' producing the oil, involving ■’ mining, retorting and refining, is 4.6 d a gallon. The New Zealand scientists suggest that Orepuki shale oil would cost 11.52 d a gallon to produce. “For purposes of discussion,” they state, “we may consider it possible to obtain a 33 per cent recovery from the shale bed by mining, then from the probable maximum in the field (6,000,000 tons) 2,000,000 tons may be obtained. If 35,000 tons were mined and' treated annually, it would represent a life of approximately 55 years for the industry. The modern treatment plant at Glen Davis, however is based oh the standard size of cracking unit with a capacity of 35,000 gallons daily, which is considered to . be the smallest possible economic unit. ‘ ' Such a iip.it,**usirig the Orepuki shale, ;/ would require 900 tons to be mined ahd'treated daily, which would mean 328,000 tons annually. On the estimated amount, of recoverable shale, these operations would mean a life of about six years.” Not Economical It would appear from the report that unless prospecting discloses considerably larger proved areas -of oil shale, the Orepuki deposit could not b,e economically worked. But the uncertainty regarding the estimates at present shows that a final conclusion at this stage is not justified. There are oil shale deposits also at Wakaia, Southland; Nevis Valley and Cambrians, Otago Central: Waihoa Valley, South Canterbury; Smoke-Ho Creek, near Blackball, on the West Coast; and at Pungaere Settlement. Northland.