Preliminary Report on an Investigation of the Bureau of Mines Regarding the Solubility of Natural Gas in Crude Oil

Abstract

Petroleum engineers generally are familiar with the investigations of Dowand Reistle, Beecher and Parkhurst, and Dow and Calkin, relative to thesolubility of natural gas in crude oil. Since the publication of the results ofthose investigations and the work of Mills and Heithecker little additionalknowledge on this interesting and important subject has appeared in thepetroleum engineering literature. The reports of Beecher and Parkhurst and Dow and Calkin agree substantially.The data from both investigations showed that, under the conditions of thetests, the solubility of natural gas in crude oil increased in directproportion to the pressure at which the gas was put into solution, and thesolubility decreased to a considerable extent with increased temperature. Thesefacts, and others relating to the changes in viscosity, surface tension andspecific gravity of the crude caused by the solution of gas in the oil, havebeen given due consideration in the petroleum industry, and the recognition ofthese facts has resulted in a great improvement in the technique of producingoil. However, in these first experiments, various grades and types of weatheredcrude oil were contacted at various pressures up to 500 lb. per sq. in. gagewith gases deficient to a considerable degree in the heavier hydrocarbons, ascompared with the gas that was originally in solution in the oil in its naturalunderground reservoir. The amount of dissolved gas that was liberated uponreducing the pressure to 1 atm. was measured. For these reasons, the completesignificance of the effect of dissolved gases in crude oil, as it occurs innature, cannot be determined directly from the data obtained under theconditions of the tests as described.