MIGRATION BEHAVIOR OF PETROLEUM-ASSOCIATED SHORT-CHAIN ORGANIC-ACIDS

In order to increase our understanding of the origin of the short-chain organic acids (SCA) found in oilfield waters, properties that influence the possible mechanisms for migration from source rock to reservoir have been examined .The preferential partition of SCA between a synthetic formation water, and a modified crude oil, has been measured and shows the dominance of water solubility. The flooding of a modified petroleum containing SCA through a water-saturated core of reservoir-type rock shows that the pore water has a great capacity for extracting the SCA from the migrating oil phase. These factors make long-distance transport of SCA (dissolved in oil) from source rock to reservoir improbable; also, focused water flow or diffusion processes are not considered realistic mechanisms for long distance transport. In situ sources of SCA are required, and hydrous pyrolysis of crude oil mixed with reservoir type minerals shows that significant amounts of SCA can be generated and that the emplaced petroleum could thus be the source of the SCA found in oilfield waters.