Research Progress and Field Trail of a New Micro-Nano Oil-Displacement System Flooding Technology

Although polymer flooding technology has been widely applied. Yet the "entry profile inversion" phenomenon occurs inevitably in its later stage, which seriously affects the development effect. In recent years, the micro-nano oil-displacement system is a novel developed flooding system. The oil-displacement system consists of micro-nano particles and its carrier fluid. After coming into porous media, it shows the properties of "plugging large pore and leave the small one open" and the motion feature of "trapping, deformation, migration". In this paper, physicochemical properties, reservoir adaptability, oil displacement mechanism of micro-nano oil-displacement system in pore throat is explored by using macroscopic physical simulation and CT scanning technology. Furthermore, the typical field application case is analyzed. Results show that, micro-nano particles have good physicochemical performance and transport ability in porous media. According to the reservoir adaptability evaluation, the matching relationships between particle size and core permeability is obtained, to provide guidance for field application scheme. By using NMR andCT techniques, its micro percolation law in porous media and remaining oil distribution during displacement process is analyzed. During the experiment, micro-nano particles presents the motion feature of "migration, trapping, and deformation" in the core pore, which can realize deep fluid diversion and expand swept volume. From 3D macro experiment, the sweep volume can be further expanded by injecting MNS and adjusting well pattern structure after polymer flooding. The dual goals of expanding sweep volume and improving oil washing efficiency can be achieved by using binary composite system (MNS and petroleum sulfonate) and ternary composite system (MNS, alkali and petroleum sulfonate). Finally, the micro-nano oil-displacement system conformance control technology has been applied in different oilfields, which all obtained significant oil increment effect. By using the research methods of interdisciplinary innovative, the oil displacement mechanism and field application of micro-nano oil-displacement system is researched. The research results provide guidance for oil companies to enhance oil recovery significantly.