关键词: 核磁共振, 聚合物, 可视化, 驱油效率, 成像技术

Abstract:

Polymer flooding has been applying in oil fields of China in large scale.Therefore it is very important to reinforce the theoretical research of polymer flooding.Polymer behavior of various slug sizes have been inves-tigated visually by magnetic resonance imaging (MRI)techniques.The core samples we used consist of three parallel permeability zones that simulate the geological structure of real fields formation.The 3-D magnetic resonance images of polymer slug movement in the core have been acquired,and pore utilization ratio variations have been studied in 3-D before and after polymer flooding.Research results show that the recovery of high permeability zone increased furtherly during polymer slug injection,and the effect of polymer injection in medium and low permeability zones were observed only after certain quantity of polymer was injected.However,the recovery of low permeability zone has increased a lot during water injection after polymer slug.The recovery in high and medium permeability zones increased a little at the same time.The 3-D NMR images show that pore utilization ratio in core dramatically increased after polymer slug injection,and this increase was related to the distance from pores to the influx.In heterogeneous samples,as polymer solution being injected,oil-water mobility ratio was raised.Microscopic and macroscopic water flooding sweep efficiencies were increased simultaneously.Therefore oil displacement efficiency was improved.

Key words: nuclear magnetic resonance, polymer, visualization, oil displacement efficiency, imaging technique