SATURATION Laboratory procedures for liquid saturation 



fall into one of two general methods: (1) the 

 retort method, whereby both oil and water are driven from the crushed core 

 by heat; and (2) the extraction method, whereby the liquids are removed from 

 the sample by solvents. Both methods have their advantages and disadvantages. 

 Speed and simplicity favor the retorting of samples, but a higher degree of 

 accuracy and reliability for at least one of the liquids in the core is evident in 

 the use of extraction methods. 



Retort Method 



One of the principal advantages of the retort method of saturation deter- 

 mination is the fact that both oil and water are recovered simultaneously in a 

 single operation. Retorts vary in capacity, heat application, and condensing 

 methods. Capacities range from approximately 35 to 150 cubic centimeters in 

 volume with vapor outlets at the top as in the familiar cast-iron mercury retort, 

 or at the bottom as in the Ruska or Keltner type. They may be gas-fired or 

 heated electrically. Condensation is obtained by circulation of cold water, or 

 immersion in an ice bath or dry ice-kerosene mixture. There are so many 

 adaptations of retorts, and all appear to serve their intended purpose in a 

 satisfactory manner. The larger capacity — from 100 to 150 cubic centimeters 

 in volume — is considered more accurate as the larger volume of sample in- 

 creases accuracy, particularly when cores of low or spotty saturation are analyz- 

 ed. In all retort methods, corrections for loss and hold-up of liquids are applied, 

 and steps are taken to distinguish between interstitial water and water of crystal- 

 lization. 



Extraction Method 



Extraction methods which can be done quite accurately, usually consist of 

 analyzing the sample for water, and measuring the total loss in weight on 

 extraction and drying. The quantity of oil present is calculated by subtracting 

 the weight of water from the total loss in weight. The following methods are 

 approved for the determination of water. 



Stark-Dean Distillation 



This procedure is similar to the sandard A.S.T.M. method of determining 

 water in petroleum products. A crushed sample of the core is transferred to a 

 porous thimble and weighed. The sample is renuxed with toluene, xylene, or 

 other liquid immiscible with water and boiled at 120 to 150C. The water is 

 caught in a calibrated glass trap. After all the water has been removed from 

 the sample, about 2 hours of refluxing, its volume is read, and the thimble 



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