Study On The Development And Mechanism Of Temporary Plugging Pill For High-Temperature Resistance Solidify Elastic Nanocomposite Gel

Well leakage is one of the most common complex issues during the process of downhole operation.Especially for the fractured formation,the serious leakage often occurs,which not only restricts the process of exploration and development but also could cause huge economic loss.At present,the most widely applied plugging agent is the one with rigid plugging material,while recently there isn’t any breakthrough in the technology innovation.Possessing the dual properties of the liquid viscosity and solid hardness,polymer gel is recognized in the field of fracture temporary plugging.Owing to the problems of poor temperature resistance and mechanical properties and insufficient gel strength,general polymer gel cannot guarantee the requirement of temporary plugging for the high temperature fracture formation.However,nanocomposite gel exhibiting both high strength,high toughness and high thermal stability have been prepared in an efficient and straightforward way via interlayer interact between the nanomaterial(sodium montmorillonite)and polymer.The nanocomposite gel properties of modulus,toughness and tensile strength can be improved.Aimed at the problems of the fracture temporary plugging under high temperature,based on the principle of solution intercalation method,this paper developed an elastic high-temperature resistant nanocomposite gel,evaluated the rheological property of the gelant solution,studied the temporary plugging pill thermal stability,working mechanism and application performance of this system.Main achievements and understanding are as follows:(1)Developed the elastic high-temperature resistant nanocomposite gel,whose temperature resistance is up to 160℃,stability of more than 10 days,adjustable gelation time of 1 to 10 hours.(2)The addition of Na-montmorillonite has huge influence on the rheological properties of the nanocomposite gelant solution,and the characteristics of pseudo plastic fluid are presented.(3)By adding Na-montmorillonite,the thermal stability of the nanocomposite gel can be significantly enhanced.The large number of hydroxyl(-OH)in Na-montmorillonite react with the water molecules and form hydrogen bonds,so that the content of bound water is increased.As the bond energy of Si-O is greater than that of C-C and C-O,the temperature-resistant property of the nanocomposite gel is further improved.(4)The addition of Na-montmorillonite enhances the mechanical and viscoelastic properties of the nanocomposite gel.With the increase of the content of Na-Montmorillonite,the microstructure of the nanocomposite gel becomes denser,and the mechanical and viscoelastic properties of the nanocomposite gel are further improved that under the same strain of 50%,the stress increased from 7.2kPa to 90.6kPa.In addition,the elasticity modulus is higher than the viscosity modulus,so that the nanocomposite gel possesses great elastic performance.(5)With the increase of fracture width,the breakthrough pressure of the nanocomposite gel gradually decreases.When the fracture width is 0.031cm,its bearing capacity is up to 12MPa,indicating a great potential in the field of fluid loss prevention and plugging of the micro-fractured formations.(6)Results of the permeability recovery test showed that for the fracture width within 0.031～0.167cm,the permeability recovery rate is higher than 85%.The research results in this paper provide theoretical basis and technical reserve for temporary plugging of high temperature fracture formation,which has certain guiding significance and practical application value.