Chemical Movement in Micellar Flooding: Determination of Sulfonates and Polymers by Liquid Chromatography

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc. Abstract Now liquid chromatographic procedures, column solvent systems and equipment used to determine petroleum and/or synthetic sulfonates and water-soluble polymers in micellar fluids are described. These new procedures are used to determine sulfonate and/or polymer in formulations and in core test effluent polymer in formulations and in core test effluent fluids. Procedures developed have been or will be automated. With automation about two man hours are required to perform 100 sulfonate analyses in a 24-hour period. Analyses have shown that monosulfonated fractions of sulfonates are usually selectively lost (adsorbed) in laboratory core tests. Introduction Micellar flooding is one of several improved oil recovery techniques currently being studied by the petroleum industry. By nature it is a complicated multiple fluid bank, chemical process. A typical tertiary micellar flooding process includes injecting a micellar fluid and following it with a mobility-control drive fluid. Most micellar fluids currently used by the industry contain brine, cosurfactants, and petroleum or synthetic sulfonates. Frequently, chemical tracers, water-soluble polymer, and/or solubilized hydrocarbons may also be present. Mobility-control drive fluids typically contain water-soluble polymers (polyacryla-mides or Xanthan gum biopolymers) dissolved in fresh water. Chemical tracers, biocides, and oxygen scavengers may also be present. As these fluid banks (micellar and mobility control) propagate through cores in lab testing, or through reservoirs in field testing, they are retained and mix with one another and with in-place brine and oil. The propagation and mixing behavior of these fluid banks is studied by collecting samples of injected/produced fluids and analyzing these samples for chemical content. Analyses of produced fluids are compared to injected fluids to study adsorption, interaction, and propagation properties of the chemicals in a propagation properties of the chemicals in a given micellar flooding process. Chemical costs make up a significant portion of the total cost of a micellar portion of the total cost of a micellar flooding process. Chemicals showing low adsorption in a reservoir environment (actual or simulated) are the most desirable chemicals for micellar flooding. Analyses used to determine the specific components in micellar fluids must be accurate, specific for adsorbed components, and relatively free from interference from other materials present in the samples.