The Property Evaluation Of Profile Control System Of Low Permeability Reservoir For Changyanggou Oil Field

The micro-nano particles sol is a new profile control agent for low permeability reservoir.The experimental study on single micro-nano particles sol profile control and displacement is carried out to design the injection parameter of micro-nano particles sol according to the geological situation of Changyanggou oil field. In order to enhance the displacement efficiency of micro-nano particles sol furthermore, the alternating injection experimental study on the system between micro-nano particles sol and surfactant is carried out. Compared with different experimental schemes, the optimum injection pattern is determined.Micro-nano particles sol is an unstable system under normal pressure and temperature.Before preparing micro-nano particles sol is light yellow viscous liquid. It is milk white liquid with fabric-like matter which may deposit in the bottom of the container after standing for a while. The interfacial tension of micro-nano particles sol with the concentration of 0.5%is reached 10-3m N/m and can remain stable for a long period of time. The core permeability of 150, 60, 30×10-3μm2 are made effective plugging effect by micro-nano particles sol with the concentration of 0.5% and 0.8%. However, when the concentration is 0.8% the plug intensity is so strong that micro-nano particles sol will access and block low permeability layer to hinder remaining oil displacement during injection process. Therefore, the micro-nano particles sol system with the concentration of 0.5% is chosen to block high permeability layer. It was shown that micro-nano particles sol have a good synergistic effect with surfactant and reduce the interfacial tension between system and crude oil sharply. At the same time gathering function of micro-nano particles sol have blocking effect on the rock pore throat to react on adjusting entry profile. More injection rounds result in the relatively low injection pressure because the injection pressure was increased step by step. The micro-nano particles sol rarely access to medium and low permeability layers in order to prevent the medium and low permeability reservoir from the damage. This method is in favor of surfactants access to medium and low permeability layers so that enhancing oil recovery furthermore. The more injection slug of the system of micro-nano particles sol and surfactant,the more injection rounds, the higher enhanced oil recovery, the better displacement efficiency. The recommended injection pattern is alternate injected 0.075 PV micro-nano particles sol and betaine for three times and then 0.05PVmicro-nano particles sol.