Construction And Plugging Mechanism Of Interpenetrating Polymer Networks Plugging Agent

Elastic particle is an important current profile control and water plugging agent,which is widely used in major oil fields.The plugging matching difficulty between elastic particle plugging agents and formation is great,and the elastic particles are easy to suffer shearing,which are poor in temperature resistance,and have weak crack plugging strength.With regard to the above-mentioned problems,the interpenetrating network polymer system was constructed and the interpenetrating network polymer plugging agent suitable for the plugging porous and cracks was prepared.Based on this,he injection and migration laws of elastic particle plugging agents in pore throats and cracks are clarified,the plugging mechanism and regulation mechanism are clarified,and plugging regulation methods are proposed.An interpenetrating network polymerization system was constructed based on the synergistic composite properties of interpenetrating network polymers.Besides,the fractional step and synchronization methods were utilized to prepare frame-like particles/PAM and cross-linked polymer resin/PAM interpenetrating network polymers.The particle size of the prepared plugging agent was made more uniform by uniformly shearing the polymer and pre-coating the particle dispersing protective agent.The microstructure of the interpenetrating network polymer was evaluated by scanning electron microscope,projection electron microscope,stereomicroscope,etc.The interpenetrating network structure was determined,and the factors affecting its strength were analyzed.The performance was evaluated using the indices of viscoelasticity,volume swell multiples,and plugging rate.The results showed that the interpenetrating network polymer was mainly elastic with temperature resistance of up to 150°C and the plugging rate of over 98%,the strength was less affected by salt,and it had better resistance to shear.Based on the change of particle injection pressure curve and migration depth,the plugging matching coefficient of elastic particles and formation pore throat was determined to be 0.21-1.10,and the plugging matching coefficient of them and fracture opening to be 0.49-0.95.An experimental method was established to characterize the elastic deformation ability of elastic particles,and an equivalent relationship formula for the conversion of plugging matching coefficients of elastic particles,rigid particles,and formation pore throat was proposed as?_T=?_G/K_a.Thus,the plugging matching technical chart for elastic particles plugging fractures was established.The visual sand-filling model and transparent reducer pipe model were used to study the migration and plugging process of particles in the pore throat.The experiments showed that the vortex at the front end of the pore throat caused by the reduction in diameter was not conducive to the bridge plugging.The influences of the viscosity and flow velocity of the carrier liquid on bridge plugging had both favorable and unfavorable sides.The formation of the effective plugging of the pore throat was mainly the filter cake plugging formed at the front end of the pore throat,and the fracture depended on the filling degree of particles in the fracture formed based on aggregation settlement and bridge plugging.CT scanning technology was used to study the plugging regulation behavior of interpenetrating network polymer particles on heterogeneous reservoirs.The results showed that the interpenetrating network polymer particles were plugging the large pore channels in high and low permeability,but the number of large pore channels in high permeability was significantly larger than that in low permeability,thus producing a good plugging regulation effect and achieving the purpose of improving the recovery efficiency.The results of double-tube parallel flooding experiments showed that the regulation could increase the recovery factor of the heterogeneous layer with and without interlayers by 26.7%and 17.0%,respectively.For heterogeneous porous media,when the permeability range was>5 and the plugging radius was?0.5 m,a good plugging regulation effect could be guaranteed.For heterogeneous fractures,when the fracture opening range was>2,the purpose of plugging large fractures and protecting small fractures could be achieved.Based on the swelling characteristics of the interpenetrating network polymer particles,a calculation method for pore throat plugging regulation was proposed.For fractures,the bridge plugging method using rigid particles in the pre-slug sections and elastic particles in the post-slug multi-level sections was used to achieve high-strength and effective plugging.Interpenetrating network polymer plugging agents can also be used in technical fields such as reservoir protection,fracturing steering,and drilling anti-leakage.The research methods on the plugging matching of particles,pore throats,and fractures can also provide technical support for the application in the above fields.