Steady, fully developed gas−particle flow in a vertical riser is analyzed. The model consists of axial momentum balances for the gas and particle phases, a radial momentum balance for the particle phase, and Poisson's equation for the electric field. Each particle carries a prescribed charge. Consequently, a radially varying electric field develops spontaneously, and this drives an electrophoretic flux of particles toward the wall. This is balanced by a diffusive particle flux. At steady state, these fluxes balance and produce a radially nonuniform particle volume fraction distribution. This, in turn, affects the axial momentum balance. The model captures important qualitative features of riser flows:  core−annular particle distribution, annular particle downflow at low riser gas velocities, and annular upflow at high gas velocities. Furthermore, the model accurately depicts results on riser flows reported by Bader et al.

With the ever growing demand for energy in the world, the need for timely and accurate data from oil fields to allow proper decision making becomes very crucial. Recent evolution in oil field technologies has made a great revolution in the oil and gas industry all over the world, leading to the emerging development of intelligent fields (I-Fields) 1-4 . The integration of I-Field technologies, whether downhole or at surface, coupled with communication networks along with sophisticated simulation and monitoring applications has led to significant advancements not only in monitoring and control capabilities, but rather also in decision making processes 5 . Therefore, the overall system upgrade has resulted in an enhancement of the field surveillance, which will lead to higher levels of oil production in these assets as a consequence of Saudi Aramco's development strategy for these fields.