LUO Litao, LIAO Guangzhi, ZHANG Yu, LIU Xiaolei, WANG Yingying, ZHANG Lin
Suspended particles in injected water can seriously plug the reservoir, which makes it hard for the water to be injected and the oil to be produced. In order to solve this problem, the plugging of a reservoir caused by suspended particles should be studied. In this paper, a core plugging experiment is designed, where 3 sizes and 5 concentrations of suspended particles are considered. The ratio of the diameter of the suspended particle to the throat diameter is defined as the compatibility. The ratio of the effluent concentration to the injection concentration is defined as the relative concentration. It is shown that when the throat diameter of the core is 0.94 μm and the water permeability of the core is 0.137～0.235×10-3 μm2, the permeability decreases and the plugging occurs after suspended particles are injected. When the particle compatibility<0.777, the relative concentration>0, a part of suspended particles can go through the core, the form of plugging is penetrable; when the particle compatibility>0.777, the relative concentration is 0, the suspended particles can not go through the core, the form of plugging is a shallow plugging; The particle compatibility 0.777 is the critical value from penetrable plugging to shallow plugging. Under an appropriate particle compatibility value, the pore volume and the plugging degree have a good linear relationship. It is suggested that the concentration should be low, the particle size should be in a limited range and the particle compatibility should be far below the critical value.
