4 CONTENTS. 
Classification of the oil-field waters—Continued. 
Distribution and significance of the constituents—Continued. p a ge. 
Other constituents. 47 
Total mineral solids. 47 
Organic and volatile matter. 47 
Criteria for comparison. 48 
Proposed classification. 49 
Composition of the oil-field waters.1. 53 
Description of the types. 53 
General comparison. 53 
Surface water. 55 
Normal ground water. 58 
Shallow water wells. 58 
Oil wells (top water). 58 
Modified ground water. 64 
Altered ground water. 67 . 
Reversed type. 67 
Brine. 71 
Mixed type. 75 
Relations of the types.-_ 77 
Vertical relations.^. 78 
Areal relations. 86 
Variation in chloride. 86 
Relations of the mixed type. 88 
Chemical relations between water and the hydrocarbons. 93 
Alteration of waters by the hydrocarbons. 93 
Nature of alterations. 93 
Reduction of sulphate. 93 
Formation of carbonate. 98 
Production of gases. 100 
Alteration of hydrocarbons by water. 102 
Solubility of petroleum constituents in water. 105 
Value of water analyses to the oil operator. 109 
Summary of conclusions. 113 
Index. 117 
ILLUSTRATIONS. 
Page. 
Figure 1. Diagram showing circulation or stagnation of the water in open and 
closed sand lenses before and after the lenses are penetrated by 
wells. 14 
2. Graphic representation of analysis 31, showing method of deducing 
the properties of a water from its composition.* 39 
3. Diagram illustrating relation of oil-field waters of the meteoric and 
connate types, and their alteration as the oil zone is approached.. 51 
4. Chart showing chemical relations of the oil-field waters. 54 
5. Variation in chemical character of waters from different depths, 
showing alterations by hydrocarbons. 79 
6 . Diagram showing increase in salinity of waters in the northern part 
of the Midway field with distance from the outcrop. 88 
7. Diagram showdng gradation between waters of the mixed type in the 
western part of the Midway-Sunset field and the brines that occur 
at the same general horizon in the deeper territory to the east... 91 
