Many reports of formation-water analyses show determinations for only carbonate, bicarbonate, sulfate, chloride, calcium, magnesium, and sodium ions. An attempt to utilize these analyses has been made by using the methods of Palmer, Sulin, Schoeller, and Chebotarev to classify some waters from carbonate and other types of formations. The purpose of this study is to determine whether these methods effectively classify waters associated with petroleum formation and whether this information can be used in exploration or the identification of formations.

It was found that the more extensive water-classification methods of Sulin and Schoeller better classify waters associated with petroleum formation than the methods of Palmer and Chebotarev. In this study, waters that were classified by Sulin's method as chloride-calcium

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or chloride-magnesium gave a positive index of base exchange when classified by Schoeller's method. Waters known to be in contact with petroleum were classified by Sulin's method and were found to be of the chloride-calcium, chloride-magnesium, and bicarbonate-sodium types, but not of the sulfate-sodium type.

It was concluded from the study that classification of the above types of data from water analyses would not be positively indicative of petroleum, but might have some application as an aid in exploration. Water classification could, in some instances, be used to identify formations, analyses for organic and minor constituents dissolved in waters associated with petroleum formation will add to the value of data from water analyses. It was found that unless extreme care is used in obtaining water samples for classification or formation identification, contaminated samples will give erroneous results.

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