,86 



NAT URL 



[January 16, 1919 



over-estimated; if it be only possible it is well 

 worth investigation ; if it be absurd the import- 

 ance of the issue renders it necessary that it 

 should be seriously confuted. It must be 

 admitted that the history of scientific opinion 

 affords numerous instances of truths finally pre- 

 vailing against the hostility of accepted opinion. 

 It is perhaps not to be wondered at that in con- 

 sideration of its urgent needs the Government 

 should have resolved to put the matter to the 

 practical test. But it by no means follows that 

 a commercial supply of oil will be forthcoming, 

 in spite of the sanguine dreams and hopes of those 

 who have pronounced favourably on the project. 

 Petroleum is an unusually elusive substance, and 

 the records of its development teem with " wild- 

 cat " schemes, some of them successful, most of 

 them failures, but all of them graced with the 

 blessings of some sober expert. The very term 

 "wild-catting" is a recognised name in oil tech- 

 nology for exploratory drilling of a purely specu- 

 lative nature based on little or no evidence; the 

 present scheme comes definitely within the limits 

 of the term. 



It must be asserted at the outset that the 

 general public report of the whole project has 

 given an unduly optimistic account of the views 

 of men of science on the problem. The measure of 

 its success will be judged, as in any commercial 

 undertaking, by the returns. Nothing short of 

 the promised oil-fields would be an adequate 

 return. The bulk of informed geological opinion 

 — and the problem is essentially geological — is, to 

 say the least, sceptical. It will therefore be well 

 at this stage to sum up the evidence in order to 

 ascertain what justification there is for the posi- 

 tion of those numerous geologists who, in spite 

 of, or rather in consequence of, their knowledge 

 of the structure and geological history of the 

 country, have been in the past, and still remain, 

 unconvinced as to the likelihood of the existence 

 of large supplies of oil therein. 



Apart from a few exceptional cases, the oil- 

 fields of the world can be divided into two main 

 groups, those in rocks of Tertiary and Upper 

 Cretaceous age, and those of Palaeozoic age. 

 The former are situated along the trend of the 

 Tertiary geosynclinals ; they are usually affected 

 bv folding movements, sometimes intensely folded 

 and thrust, and generally show abundant surface 

 indications of their contained petroleum. A few 

 important exceptions occur, such as the Mexican 

 and Gulf States fields, where there is little fold- 

 ing, and surface evidence of the hydrocarbons is 

 often absent. These exceptions are in their struc- 

 tures more allied to the Palaeozoic fields. The 

 latter are largely confined to North America ; they 

 range in age from the Ordovician to the Carboai- 

 ferous ; folding is either absent or is of a gentle, 

 open nature, and the presence of surface indica- 

 tions of petroleum is exceptional. 



In Britain the Tertiaries would not be seriously 



considered as a possible source of petroleum in 



large quantities. Their extent is limited, their 



structures are in the main synclinal, and they have 



NO. 2568, VOL. I02] 



been riddled by wells in a search for water. 

 .Neither do the Mesozoic strata yield indications 

 of a more hopeful character. The claims of Dr. 

 Forbes Leslie of abundance of free oil in the 

 Jurassic strata near the Wash have been nega- 

 tived by the work of all other investigators. It 

 is to the Carboniferous system of the Palaeozoics 

 that niosi attention has been directed as the pos- 

 sible source of petroleum. The indications of this 

 material are too numerous to mention here in 

 detail. An excellent account of them will be found 

 in W. H. Dalton's paper on "The Oil Prospects 

 of the British Isles," 1 and a further summary is 

 contained in a recent publication by H.M. Geo- 

 logical Survey on " Lignites, Jets, Kimmeridge 

 Oil-shales, Mineral Oil, Cannel Coals, and Natural 

 Gas." 2 Most of these petroleum occurrences are 

 insignificant and ephemeral ; they range over the 

 whole gamut from solid asphalt to natural gas. 

 In a few cases, however, the supply of oil has 

 been sufficient to be exploitable on a small scale, 

 though only for a limited period. Thus at the 

 Riddings Colliery, Derbyshire, a yield of oil 

 averaging about 300 gallons a week was obtained 

 for some years, and was the primary cause of 

 the development of the Scotch oil-shale industry. 



Judging by what has been published on the 

 subject, it is to be presumed that the extensive 

 scheme which has been inaugurated is largely 

 based on the selection of suitable areas where 

 Carboniferous rocks with suitable structures 

 either outcrop or will be reached at convenient 

 depths. The initial test near Chesterfield is obvi- 

 ously based on this principle. The sandstones of 

 the Millstone Grit series and the porous horizons 

 of the Upper Carboniferous Limestone will be 

 available porous reservoir rocks, while the Coal 

 Measures and Pendleside Shales will be relied on 

 to constitute the overlying impervious strata 

 which are essential to prevent the oil from escap- 

 ing. The basis, then, of the project is simple. 

 It rests on the numerous small indications of 

 natural hydrocarbons the majority of which have 

 been located in the Carboniferous strata, and it 

 relies on the location of suitable geological struc- 

 tures for test-wells. Other formations will prob- 

 ably be tested, but presumably the main reliance 

 will be placed on the Carboniferous. 



Having now considered the guiding principles 

 of any search for free oil in this country, it 

 remains to discuss the possibilities of success. It 

 will be generally agreed that the bona-fide petrol- 

 eum indications are quite numerous, though they 

 are mainlv insignificant. Further, it will be con- 

 ceded that in many, if not in most, cases they 

 are examples of natural crude petroleum or 

 asphalt, as distinct from the products of destruc- 

 tive distillation from coal seams by local igneous 

 metamorphism, though examples of this action 

 are quite common. Moreover, it will be admitted 

 that there are suitable anticlinal structures for oil 

 concentration, and abundance of porous strata 



1 Journal of the Institution of Petroleum Technologists, vol. iv., No. 13, 

 p. 37, 1917. 



2 Mem. Geol. Survey. Special Reports on the Mineral R' 



