U.S. Gulf Coast geopressured brines studied to date contain small amounts of C6+ hydrocarbons which are primarily aromatic in nature. They range from benzene to substituted anthracenes. In addition, the brines contain a variety of ions and light, C1 to C6, aliphatic hydrocarbons. The primarily aromatic hydrocarbon mixture was collected at −78.5°C and is referred to as a “cryocondensate.” It contains at least 95 different compounds and, from the carbon isotropic ratios, appears to be of terrestrial plant origin. For the only U.S. DOE geopressured energy design well studied for an extended period of time, i.e., the Glady’s McCall well, the concentration of the cryocondensate in the brine was observed to increase prior to the onset of oil production. It is postulated that the change in the brine cryocondensate concentration as a function of the cumulative brine volume produced from the wells results from an extraction of additional aromatic components from oil migrating into the production zone from adjacent shale. When sufficient oil has migrated, it is produced along with the brine.

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