Physico-Chemical Formulation of Surfactant-Oil-Water Systems

Since the creation of FIRP Lab., we have been improving upon the quantification of characteristic parameters of the components of a surfactant-oil-water system: equivalent salinity, oil EACN, characteristic parameter of surfactants. New methods of evaluation of these parameters have been developed. Specific studies have dealt with the effect of alcohols and temperature. Coupled effets of composition parameters and formulation variables have been interpreted. The EACN is now available for a large number of polar and terpenic oils.

Complex Systems - Surfactant Mixtures - Fractionning and Segregation
This topic has been carried out in concerted R&D with other teams at University of Pau – France (Lab. des Fluides Complexes) where fractionning has been interpreted and University of Zulia-Venezuela (Lab. de Petroquímica y Surfactantes) where analytical HPLC-HPSEC methods have been developed. The approach consists in understanding how to mix surfactants (a very comon practice) in the whole system to attain a specific property at interface. A particularly interesting case is when the surfactants are sensitive to pH as with carboxylic acids or amines. Recent studies have dealt with ionic and nonionic surfactants whose change of formulation by dilution allows to solve the problem of keeping constant the optimum condition after injection.

New additives, “Lipophilic Linkers”, Extended Surfactants
We pioneered in this topic 20 years ago with our colleagues at University of Pau – France in our work to boost the solubilization of polar oils in microemulsions for a major pharmaceutical transnational company. We introduced the concepts of Lipophilic Linker and then of Extended Surfactant. Recently we have been synthesizing different extended surfactant species, particularly with sugar head groups. The properties of these surfactants are now characterized and they are used in several applications involving conventional and polar oils, particularly natural products.

Emulsion Properties
In the past 25 años we have carried out many project to develop a relationship between the emulsion properties (type, drop size, stability, viscosity) and the physicochemical formulation, as well as the emulsification protocol. A systematic 2D map representation was found which is quite general and allows predictions to be carried out on most system. The effet of the drop size and distribution on the viscosity has been studied, particularly in bimodal cases..

Formation and Inversion of Emulsions
This is a R&D area quite developed in FIRP Lab. Various projects have allowed a quite complete understanding of the many effects (formulation, composition, stirring energy and time, phase viscosity, addition protocol) which are relevant in determining the conditions and mechanisms of the different types of inversion (transtitional, catastrophic and combined). Characteristic of standard and dynamic inversion cases were interpreted and maped in a systematic way, and a valuable know-how has emerged as far as industrial applications are concerned.

Mini- or Nanoemulsions – Spontaneous Emulsification – Phase Transition
Mini or nanoemulsions are emulsions, that is diphasic systems, with extremely small droplets, which give them their translucid aspect and high viscosity. Such systems have many applications in foods, pharmaceuticals, cosmetics, paints, cutting oils, etc ... Miniemulsions are often stabilized entropically and may be produced with a low energy level by phase transition involving some kind of inversion. This kind of emulsion is not generally prepared by brute force, but by phase transition through a formulation or temperature change, catastrophic or combined inversion, or mixed composition/transition transition. Some of Lab. FIRP group have worked with research centers in Spain, Japan and France.

Rheology and stirring of dispersed systems – Relationship with formulation – Emulsified transport.
Emulsions are dispersed systems with perculiar rheology, whose fine-tuning is often crucial as far as applications are concerned. Since the early 1980’s, we have been working on the relationship between formulation, composition and protocol with emulsions properties, particularly their rheology and its application to emulsified transport of heavy crude oils.

Foams
FIRP Lab. foam R&D team was created in the mid-1980’s. Several early projects were dedicated to separation methods by foaming, and more recently we have tried to relate the formulation to the foaminess and foam persistence with some succes. Some work have been dedicated to foam rheology issues. A high pressure (200 atm) high temperature (120 °C) column equipment was developed with CITEC-ULA to test foaming drilling fluids formation and stability for our industrial partners.

Membranes and related Processes
This R&D group is dealing with the separation on different kinds of membranes: solid, liquid, inorganic and organic membranes, multiple emulsion and electrodialysis. In the last decade the flow of emulsion on membrane has been studied, and recently the emulsion production on membrane has been understood. Applications have been developed in waste flows from petroleum and other industries like milk processing. Membranes have been used too to separate lignin from black liquors.

Lignin and wood extract: Characterization and recovery
FIRP Lab lignin team characterizes the black liquor from pulp plants, and has dealt with the separation and use of lignin. This group has been working in association with the Laboratory of Petrochemistry and Surfactants at University of Zulia (Maracaibo) which is involved in the chemical modification of lignin, and with the Wood department from North Carolina State University in USA. Our group has dealt with the deinking of paper, the separation of fibers, and the characteristics of wood extracts.

Petroleum Applications
This area is one of the major R&D effort of FIRP Lab. in the last 25 years, both in dedicated time and real world projects. It has also been a major source of contracts and financial support of our Lab. through services, training and formation activities. The main subject matters have been:.

• Enhanced Oil Recovery by ASP. This is the first research-development topic in which FIRP researchers have been involved since its genesis in 1975-1980. This R&D area has never been abandoned in spite of unfavorable economic conditions in the 1980-1990’s. With the regain of interest in the past decade, we have been working with several companies in Venezuela and abroad. In the past 3 years we started again to realize some fundamental research work. We have currently two of our staff members carrying out doctoral dissertations dedicated to unsolved practical problems. The first one deals with a method to eliminate the variation of optimum formulation when the injected fluid is diluted in the reservoir. The second one is about non-newtonian rheology to improve the sweep efficiency after the surfactant slug. Thanks to the contribution of CITEC-ULA we have developed a spinning drop tensiometer to measure ultralow tensions.  Our Lab. has currently half a dozen of such aparatus to offer a quick service to our partners.

• Heavy Crude Oil Emulsions, with about 30 R&D projects for INTEVEP and other PDVSA subsidiaries since 1980. Our research programs with PDVSA have been dealing with physicochemical formulation, surfactant mixtures which are insensitive to temperature, activation of acids present in crude oils, formation of gels with nonionic surfactants, stabilization of emulsions, and rheology of dispersed systems. In recent years we have been working with transnational companies on emulsified transport, and formulation of fuel emulsions, particularly with heavy residual cuts.

• Asphalt Emulsions. Studies have been dedicated to the heteroflocculation of cationic asphalt emulsions on granulated material, both from the fundamental and practical points of view. We have built a pilot plant to produce 2 tons/h of asphalt emulsions in order to provide a unique-in-Venezuela real-world service to our industrial partners, which are small regional companies.

• Drilling Fluids. We have developed for our industrial partners formulations for drilling-related fluids, such as spacers, formation damage recovery cleaners, and filter cake removers, with a variety of systems including microemulsions which are able to unplug wells and considerably increase their production.

• Deshydration. Our researchers pionnered in the application of the concept of optimum formulation to the attainment of a proper dehydration formulation more than 25 years ago. We have been working on quantifying formulation concepts to optimize demulsifiers with respect to each crude oil through 3 doctoral dissertations in the past 10 years. We have developed with CITEC-ULA an electrostatic dehydration equipment that allows bottle testing of formulations in 15 minutes instead of hours. We provide counselling, services and training for several small companies in Venezuela.

• Suspemulsion. In the past 5 years we have been working on suspemulsions, i.e. emulsions stabilized with solid particles and surfactants. There are many petroleum and non-petroleum applications, but the general understanding is rather uncertain and it is currently difficult to forecast the simultaneous effect of a change in formulation on the particle behavior and the emulsion stability. Consequently the issues are still quite empirical.