Experimental study on pressure-decreasing performance and mechanism of nanoparticles in low permeability reservoir

摘要

The use of nanoparticles for low-permeability reservoirs is a cutting-edge frontier technology in oil field development. By investigating the optimization of nanoparticles and the implantation scheme, we have achieved the goal of using nanoparticles efficiently and economically. In this study, we tested the basic properties of nanoparticles Finally, we selected an ideal nanoparticle to conduct further experiments and innovatively applied micro-tubes to simulate the core pores by simplifying the model structure. The effects of the nanoparticle injection rate and pore size on the pressure reduction were studied and verified by core-flooding experiments. The experimental results showed that the pressure-decreasing ability of the nanoparticles exhibited greatly pressure-decreasing efficiency, initially an increasing trend and followed by a decrease with an increase in the injection rate. The hydrophobic nanoparticles adsorb on the surface of the rock pores, which fills the rough surfaces in the rock pores and forms a stable hydrophobic surface film. This nanofilm improves the roughness of the rock pore surface and replaces the hydration layer formed by the injection of water so that the surface of the pore wall is transformed from a hydrophilic to a hydrophobic state, which improves the core wettability, avoids hydration expansion, reduces interfacial tension, improves the pore diameter and results in a decrease in the flow resistance. This study has significant impact of nanoparticles on effective and economic development in low permeability reservoirs, which could solve to high injection pressure problem during water injecting to supplement energy.