Technologies and Mathematical Modeling of Fines-Assisted Oil and Gas Recovery
Doctor of Philosophy (Ph.D.) 2012
Australian School of Petroleum
The University of Adelaide
This is a PhD thesis by publication. It includes seven published/accepted for publication journal papers and two submitted papers in academic peer reviewed journals. The content of the thesis is also published in ten full volume technical papers of Society of Petroleum Engineering (SPE).
The thesis develops a theory for single and two-phase flow in porous media accounting for mobilization, migration, and straining of the natural reservoir fines.
This phenomenon has been widely reported in laboratory studies and also well history data. The existing mathematical model, widely used in petroleum reservoir simulation, does not agree with laboratory observations. It contains phenomenological empirical constants which cannot be predicted theoretically.
The new closed system of governing equations, proposed in the current thesis, is free of the above mentioned shortcomings. The proposed system contains a new theoretical function describing the rock capacity to liberate fines so-called maximum retention function. This function is based on the micro scale conditions of mechanical equilibrium of fine particles in the porous space. The mechanical equilibrium
condition is a torque balance of drag, lifting, electrostatic, gravity, and capillary forces. The maximum retention function is derived for both single-phase and twophase flows in porous media. The comparison between the modified particle detachment model and the maximum retention function and laboratory and well data has shown a good agreement, which validates the model.
An exact analytical solution for single-phase flow in porous media with alternating velocity accounting for fines lifting has been derived, allowing for mathematical description of a laboratory test on the suspension injection into reservoir cores with alternating velocities. Good agreement between the laboratory test results and the mathematical modeling predictions validates the theory developed.
Both analytical and numerical models for two-phase flow with induced fines migration have been developed. In reservoir scale approximation, the equivalence between the fines assisted water-flood and adsorption-free polymer flood has been investigated. It allows using the existing commercial simulators to model low salinity water-flood. The results of the modeling allow proposing a new technologically effective and economical method for improved sweep efficiency by fines assisted water-flooding.
Moreover, modeling of low salinity water injection shows that permeability reduction due to induced fines migration can slow down the encroaching water in oil/gas reservoir under strong water support. It decreases water production during pressure depletion of oil/gas reservoirs and improves the recovery. Also, a small volume injection of low salinity water can be used to reduce the water conning problem in oil/gas wells and prolong the wells production life.