Experiments For Initial Fracture Damage Control Mechanism

As an efficient method in old well stimulation,re-fracture technology is adopted worldwide.The core of re-fracturing technology is using temporary plugging agents to plug old fracture,forcing fracturing fluid to flow to non-fracturing formation.However,the common polymer temporary plugging agents are hardly dissolved completely,which will cause formation and fracture damage after fracturing job.Based on the requirements of old fracture non-damaging technology proposed by other scholar,this paper studied mechanism of formation and fracture damaged by polymer temporary plugging agents and old fracture non-damaging performance of Fuzzy ball temporary plugging fluid by laboratory experiments.This paper summarizes the reasons why polymer temporary plugging agents will cause formation and fracture damage.Because the polymer temporary plugging agents cannot be dissolved completely,the residue will cause formation damage.Meanwhile,the solid particulates and low molecular weight polymer also bring formation damage.The results show that Fuzzy ball temporary plugging fluid has less residue,higher solubility,easier gel-breaking,high permeability recovery and less formation damage compared with common polymer temporary plugging agents.All these advantages proved that Fuzzy ball temporary plugging fluid can meet the requirements of old fracture non-damaging technology.Meanwhile,filed application proved that Fuzzy ball temporary plugging fluid is a new kind of solid free temporary plugging fluid.