In the San Joaquin Valley of California (Rogers, 1917), it has been found 

 that the surface waters and the normal underground waters, of meteoric origin, 

 outside of the petroleum fields, are rich in sulphate; whereas, in the petroleum 

 fields, the concentration in sulphate of the waters decreases in depth and is 

 practically absent in the field waters. The sulphides and hydrogen sulphide 

 appear near the level where the sulphate commences to decrease, and they exist 

 among the numerous waters located above petroleum beds. The quantity of 

 sulphides in the deep waters is obviously directly proportional to the quantity of 

 sulphate in the water located just above. 



In the anticline of Polasna-Krasnokamsk also, the hydrogen sulphide has 

 no distribution. The concentration of H 2 S is particularly high in the top beds 

 and is strong in the suboil beds, but it is extremely weak in the edge waters. 



In some deposits there is the almost total absence of sulphates and, at the 

 same time, complete absence of H 2 S. This fact indicates that the reduction of 

 sulphates was made a long time ago, that it was made completely, and that it 

 is now arrested. This fact implies, in consequence, the existence of a bed in 

 which water and petroleum are found in an enclosed hydrostatic system (no 

 movement of fluids) . 



In some other instances of absence of SO4, H 2 S is present. It is admitted 

 that H 2 S proceeds from an ancient reduction of sulphate and that it is stored 

 in the deposit as other gases are stored. But it can just as well be thought that 

 a reduction of sulphates is in progress, which, in consequence, necessitates a 

 relatively weak introduction of foreign water in the water deposit, such that the 

 phenomenon of reduction can be produced in a complete or almost complete 

 manner. This, in particular, could be an explanation of the water deposits of 

 Rumania and California. 



In West Texas, waters saturated with calcium sulphate, contain large 

 quantities of H 2 S. The reduction of S0 4 to H 2 S no doubt occurred in a foreign 

 water that later penetrated the deposit. 



Hydrogen sulphide can exist in large quantities due to its high solubility. 

 The quantity of S, S 2 03, and SO3 ions is generally small. Where there is a 

 reduction of S0 4 , there is also an increase in the content of carbonic gas (C0 2 ) 

 in the petroleum deposits, an increase in the content of C0 3 combined with 

 water; and an increase of free C0 2 . The reduction of S0 4 very often seems to 

 cause a decrease of CO3 content of the waters by the precipitation of CaCOs. 



Nitric and Nitrous Ions (NO,, NO ; ) 



The nitric and nitrous ions (N0 2 , NO3) of connate water have been the 

 object of very few determinations, except in Illinois. 



A few measurements executed outside of Illinois give only the concentration 

 of several milligrams, rarely of ten milligrams. It is evident that the pressure 



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