To establish and improve recovery efficiencies of acidic crude oils with alkaline agents this project includes studies on displacement dynamics, chemical transport, emulsion flow, and interfacial tensions. Displacement tests to date of Wilmington oil-field cores with alkali at reservoir temperature and rate show low tertiarY oil recoveries. Application of a simplified chemical oil displacement model for the caustic process reveals the importance of establishing mobility control. Caustic movement in Wilmington reservoir sands is influenced by a reversible adsorption component and an irreversible dissolution contribution. The importance of each of these transport mechanisms for slug design is outlined. New cation exchange capacity data are presented for the Wilmington sands, and the use of these data to design effective preflush slugs is enunciated. Progress to date on modeling dilute stable emulsions flow in porous media with filtration theory is summarized. Extension of this theory to describe secondary emulsion flooding is described.

To establish and improve recovery efficiencies of acidic crude oils with alkaline agents this work includes studies on displacement dynamics and modeling, chemical transport, and emulsion flow and displacement. An equilibrium chemical displacement model is presented. The unique feature of this theory is that the chemistry of the acid hydrolysis to produce in-situ surfactants is rigorously included. Calculations with the model reveal delayed and reduced tertiary oil recovery for adverse mobility ratios, and the critical importance of quantifying alkali rock interactions. Design of alkaline floods based only on properties of the fluid phases, such as interfacial tension, interfacial viscosity, or emulsion stability, can be obviated by the paramount role of rock-chemical reactions.

The type and amounts of clays and clay minerals present in typical oil producing formations, which may be candidates for application of enhanced recovery methods, are evaluated. After identification of the clay minerals present, tests are run on the extracted clay fractions to determine their cation exchange capacities, surface areas and chemical loss characteristics. Flood tests are run on extracted cores and then on native oil-bearing core samples to evaluate the magnitude of chemical loss and to note the change in flow characteristics as different fluids, which might be used in enhanced recovery operation, are flowed through the core.

This study evaluates the type and amounts of clays and clay minerals present in typical oil-producing formations that may be candidates for application of EOR methods. After identification of the clay minerals present, tests are run on the extracted clay fractions to determine cation-exchange capacities (CEC's), surface areas, and chemical-loss characteristics. Flood tests are run on core samples to evaluate the magnitude of chemical loss and to note the change in flow characteristics while different fluids, which might be used in EOR operations, are flowed through the core. This background material is used to test predictive equations developed for screening reservoirs for EOR applications and for optimizing process variables. Techniques to counter the effects of rock/fluid interactions are considered.