viii, a, 5 Pratt and Smith: Petroleum Resources 365 



However, the petroliferous shale and interbedded sandstones 

 make up the larger part of at least 50 meters thickness in some 

 places, and probably approach this aggregate thickness on an 

 average. Even with the low petroleum content specified, these 

 beds would store up a volume of oil which assumes commercial 

 proportions. Distributed throughout the shale, the oil could 

 hardly be recovered in any quantity by ordinary methods, but 

 if the saturation is great enough to cause an accumulation in 

 the interbedded sandstones commercial exploitation should be 

 possible. If the lenses of sandstone in the Bacau stage which 

 are not exposed at the surface and consequently have not been 

 broken open by erosion are saturated, the usual absence of oil 

 in the sandstones along the outcrops of the petroliferous beds 

 must be attributed to the rapid volatilization of the light oil 

 from the surface of the porous materials. 



The pore space in the interbedded sandstones is an important 

 factor in this connection. Much of the coarser grained sand- 

 stone is so poorly consolidated that the actual pore space in the 

 beds as they occur cannot be determined. A sample of the 

 harder fine-grained sandstones taken from the vicinity of the 

 Ajus petroleum seep contains 11 per cent of pore space. Prob- 

 ably the coarser sandstones are more porous. 



Earlier examinations of Bondoc Peninsula have led to the 

 published statement by two independent observers that the sur- 

 face showing of oil is as favorable as those in other fields which 

 have become large producers after development. It may now 

 be added that the oil is associated with certain zones in an 

 extensive series of shale and sandstone, and that the geologic 

 structure is locally suitable for the accumulation of whatever 

 petroleum is present. 



A definite estimate of the quantity of petroleum available 

 in this field, based solely on the data recorded in this report, 

 in advance of any exploration is not justified. It would be a 

 simple matter to estimate the thickness and area of the sands 

 in the Bacau stage which could be reached by the drill in 

 structurally favorable regions and to calculate the quantity of 

 petroleum contained in these sands on the basis of their porosity 

 as stated above, but the figure so obtained would have little 

 real significance. The present knowledge of the field, however, 

 does afford a basis for the belief that properly located wells 

 could be made to yield at least small individual productions 

 from the Bacau stage of the Vigo shale. From the thinness of 

 the sandstone beds and the alternation of sandstone and shale 



122679 5 



