Study on preparation and plugging effect of sawdust gel particle in fractured reservoir

In order to solve the problem of conventional preformed particle gel (PPG) with relatively high cost and poor strength and shearing resistance, a preformed sawdust gel particle (S-PPG) with a more superior performance than PPG was presented. A series of S-PPG with different mass ratio of sawdust particles to gelling liquid were prepared with free radical polymerization. It makes acrylic acid and acrylamide as polymerization monomers, N,N′-methylene bisacrylamide as crosslinking agent, ammonium persulfate as initiator and sawdust particles as enhancer. In general, enhancer content was less than 1%, but the content of enhancer in this work was increased by about 20–30%. The microscopic morphology, swelling property, viscoelasticity, yield stress, creep-recovery characteristics and shearing resistance of S-PPG in the formation water had been studied. The plugging behavior of S-PPG was studied using core flooding test. The results indicated that the swelling ratio of S-PPG (1:5) in the formation water was 8. S-PPG showed better viscoelasticity properties, shearing resistance and higher yield stresses than PPG. Moreover, the plugging rate of the plugging system with 3000 mg/L S-PPG (1:5) improved from 85.1% to 90.5% in fracture core compared with PPG. S-PPG (1:3) improved the plugging rate from 85.1% to 91.9%. The research results provide an alternative plugging material in fractured reservoirs.