No abstract

Summary Studies on the application of transition-metal catalysts for heavy-oil or bitumen in-situ upgrading were conducted in the absence of a porous medium, mainly measuring the characteristics of heavy oil in reaction with metal ions at static conditions with the help of a magnetic stirrer. Metal species in ionic form are not soluble in oil phase. Therefore, metal particles, as inhomogeneous catalysts, are considered in this paper. Furthermore, dynamic tests in porous media are needed to clarify the injection possibility of the metal particles and their effect on in-situ upgrading of heavy oil. Injection of metal particles may deteriorate the recovery process by damaging porous media because of attractive forces such as van der Waals and electrostatic forces between particles and porous rock. A better understanding of these forces and their importance in the retention of particles is required. In this paper, the catalysis effect of pure nanometer-sized nickel during steam-injection application was compared with that of an industrial catalyst such as micron-sized Raney nickel. The changes in the viscosity, refractive index, and asphaltene content were measured after each test to analyze the catalysis effects. Nickel nanoparticles showed a better catalysis compared with Raney nickel. The approximate optimum concentration of the catalysts was determined. Then, the catalysis effect of nickel nanoparticles was studied in the presence of sandpack as a porous medium. The results showed accelerated catalysis in presence of the sands. Also, nickel nanoparticles improved the oil recovery factor. The next phase of this paper studies the injectivity and transport of nickel particles. The injected suspension was stabilized by use of xanthan gum polymer and ultrasonication. The effect of solution pH, which controls the magnitude of the repulsive electrostatic forces, was clarified. Stabilization of the metal particles’ suspension was studied at different pH values through zeta-potential measurements. Also, the zeta potential of the recovered suspensions was studied to confirm the stability of the suspension during travel through the porous medium. Depending on the size, particles carry different charges and have different settling velocities. Therefore, the stabilization pH and dispersant concentration were different from one sample to another. The results of the injectivity tests confirmed the lower retention and better injectivity of nanoparticles in comparison with micron-sized particles.

Conventional (steam injection) and unconventional (electrical/electromagnetic heating) heavy oil/bitumen recovery methods require a high amount of energy. The efficiency of these methods can be increased by improving the energy transfer to the oil for viscosity reduction. It has recently been shown that micron-sized metal particles improve the efficiency of some ex-situ processes such as coal liquefaction and pyrolysis, heavy oil upgrading, oil shale recovery, and heavy oil viscosity reduction. This idea, with some modifications, can be applied to reduce the energy input of the aforementioned recovery methods for more economical heavy oil/bitumen production. The major contribution of the metal particles is expected to improve viscosity reduction by reducing the amount of the required energy. The objective of this work is to clarify the mechanics of additional viscosity reduction using nano-size metals during thermal applications through a series of experiments. In the absence of electromagnetic fields, exothermic chemical reactions and thermal conductivity enhancement are the two important functions of metals to cause a reduction of oil viscosity. Two sets of experiments were conducted to investigate these mechanisms. Different metal types including iron, nickel and copper with different sizes and their different compounds were selected. The viscosity of oil samples, mixed with these particles, was measured. The tests were repeated at different temperatures. Also, the effect of the metal particles on heat transfer enhancement was examined. Nano-sized particles were found to have a remarkable effect on heat transfer through heavy oil. The experiments provided a good understanding of the ongoing mechanisms that would lead to a viscosity reduction by the addition of metal particles. The concentration, type, and size of the particles were found to be highly critical on viscosity reduction. The optimal values of these parameters were identified. The results and observations are expected to be useful in further studies and applications as to the efficiency improvement of the thermal applications for heavy-oil/bitumen recovery.

No abstract

Studies on the application of transition metal particles for heavy oil or bitumen up-grading were conducted in the absence of a porous medium, mainly measuring the characteristics of heavy-oil in reaction with metal ions at surface conditions. Dynamic tests on porous media are needed to clarify the injection possibility of the metal particles and their effect on in-situ recovery and up-grading heavy oil. Injection of metal particles may deteriorate the recovery process by damaging porous media due to attractive forces such as van der Waals and electrostatic forces between particles and porous rock. A better understanding of these forces and their importance in the retention of particles is required.In this paper, the injectivity and transport of nickel particles was studied. The injected suspension was stabilized using Xanthan gum polymer and ultrasonication. The effect of the solution pH, which controls the magnitude of the repulsive electrostatic forces, was clarified. Stabilization of the metal particles suspension was studied at different pH values through zeta potential measurements. Also, the zeta potential of the recovered suspensions was studied to confirm the stability of the suspension during travel through the porous medium. Depending on the size and type, particles carry different charges. Therefore, the stabilization pH and dispersant concentration was different from one sample to another. The results of the injectivity tests confirmed the lower retention of nanoparticles in comparison with micron-sized particles.A steam simulation process was applied in the presence and absence of metal particles, and heavy-oil recoveries were monitored. Higher recovery was achieved when nickel nanoparticles were used. The changes in asphaltene content and the viscosity of the heavy oil confirm the catalytic effect of the nickel nanoparticles on the in-situ upgrading of heavy-oil.