G. Pusch

Pyrolysis and combustion kinetics of crude oils, asphaltenes and resins in relation to thermal recovery processes

Abstract Knowledge of crude oil pyrolysis and combustion kinetics is necessary in oil production for thermal methods of enhanced oil recovery. During oil recovery by in situ combustion, a crude oil undergoes chemical changes (pyrolysis reaction) and physical changes (dilution by the cracking products, vapourization and condensation of some fractions). Both phenomena are important for oil production. This work aims at studying the effect of the oil composition, characterised on the basis of light hydrocarbon, resin and asphaltene contents, on the pyrolysis kinetics of the oil and combustion kinetics of the fuel, examined under idealised reservoir conditions. The results of these investigations show that the colloidal composition of oil as well as the transferability and heat transfer characteristics of the pyrolysis medium have a pronounced influence on the fuel formation and composition.

Dual surfactant systems for enhanced oil recovery at high salinities

Abstract Surfactants for the enhanced recovery of crude oil were studied with a model oil by means of phase experiments and core floods. As single surfactants, alkylphenol ether sulfonates have only a limited potential for enhanced oil recovery at high salinities. If the surfactant is made hydrophilic enough to dissolve in brine it is no longer able to form a microemulsion with the hydrocarbon. This problem may be solved by using dual surfactant systems consisting of alkane sulfonate and ether sulfonate. At high salinities these surfactant combinations dissolve in brine to form a homogeneous dispersion. Such mixtures are also cheaper than the ether sulfonate alone. Core floods with a model oil demonstrate the efficiency of these surfactant mixtures and their compatibility with a modified polyacrylamide polymer specially developed for high salinity reservoirs.

Mobilization and Banking of Residual Oil in High Salinity Reservoir Systems With the Use of Aqueous Surfactant Solutions of Ethoxylated Carboxymethylates

Highly saline reservoir brine and crude oil with ethoxylated carboxymethylates and cosolvents show a complicated phase behavior. Easily obtainable and well defined indicators are therefore required to characterize phase conditions, which prevail in displacement processes. The phase inversion temperature (PIT) has been investigated with respect to its ability to discern phase transformation in oil-brine-surfactant systems. PIT proved to be very sensitive to changes in salinity, ionic strength, water-oil ratio and surfactant concentration, which simultaneously are responsible for phase inversion of chemical systems in the porous medium. 18 refs.

Simulation of the interaction of fractures and intergranular type porosity for fluid flow predictions

Natural or artificial hydraulic fractures contribute strongly to fluid flow in reservoir systems with a low matrix permeability. In deterministic reservoir modeling concepts the geometry and structure of fracture flow networks is improperly considered.