ミクロスケ－ルからの現象解明に基づいた炭化水素資源の増進回収法の開発

An important aspect of any enhanced oil recovery (EOR) process is the effectiveness of process fluids in removing oil form the rock pores at the microscopic scale. Capillary and viscous forces govern phase trapping and mobilization of fluids in porous media. Understanding the role of pore-level mechanisms is essential to the design of EOR process in oil-fields. In present study, first, we observed the pore-scale mechanisms of surfactant flooding and water-alternated-gas (WAG) scheme by using the porous plates. Reduction in the interfacial tension between oil and water due to surfactant results in the enhancement of oil productivity. During this process, some fraction of oil tends to be in an emulsion state, which suggests that the snap-off mechanisms are changed with the reduction in surface tension. In WAG processes, injection of gas both before and after surfactant injection facilitates to bring surfactant to the interface between oil and water by blocking the paths of water break-through. Finally, the oil trapping process in water flooding was visualized in a three-dimensional packed bed of glass beads by means of X-ray CT scanning. Piston-like displacement in a pore-network scale is primary mechanism in oil trapping comparing with the snap-off at pore-throat.