Preparation And Performance Evaluation Of Organic Nano Plugging Agent

Due to the national energy strategy requirements,shale gas mining is becoming more and more important.In order to safely drill the required formation during the water-based drilling fluid drilling process,nano-scale particles are needed for effective sealing.Based on the research background,this paper finds that there are micro-particles in the water-based drilling fluid,and there are no nano-scale particles,and the inorganic nano-materials have the disadvantages of easy agglomeration and poor sealing effect.Based on the above problems,this thesis takes organic polymer nanoparticles as the research object,and studies it from three aspects:preparation,performance evaluation and micro-blocking simulation.The main research contents are as follows:First,in the preparation of polymer nanoparticles,using methyl methacrylate(MMA),hydroxyethyl methacrylate(HEMA)as the reaction monomer,potassium persulfate as the initiator,based on the principle of emulsion polymerization,preparation A polymer nanoparticle plugging agent was produced and the product was recorded as DG1.The optimum reaction conditions were as follows:initiating dose:0.5%(percentage of total monomer mass),stirring rate:150 r/min,optimum ratio of reactive monomers:HEMA:MMA=3:1,reaction monomer concentration:20%,emulsifier ratio:4:1(mass ratio),65?constant temperature water bath for 4 h.Secondly,in the aspect of plugging performance evaluation,this paper uses the artificial mud cake with the same permeability as the shale formation as the simulated stratum,and evaluates the plugging performance by testing the change of the permeability of the mud cake before and after sealing at a certain temperature and pressure..Adding 3%DG1 to the sulfonated drilling fluid,the rate of permeability reduction of the mud cake reached 63.4%,the plugging effect was good,and the effect on the viscosity of the drilling fluid was not significant.Third,the plugging experiment was simulated with PFC2D software.The plugging process under various conditions was simulated.When the concentration of the plugged particles reached 4%,the plugging effect was the best and remained unchanged,which was confirmed by the previous plugging experiment results,which provided a support for the subsequent micro-blocking simulation study.Good foundation.