Research On High Temperature Fracturing Temporary Plugging Agents

Repeated fracturing is an important means of increasing production in low permeability reservoirs.One of the key techniques for repeated fracturing is the fracturing temporary plugging agent.High quality plugging agent has strong adhesion to the rock surface,can quickly form an effective filter cake,has a high breakthrough pressure gradient,and can automatically release the plugging after the fracturing construction is completed.The low permeability reservoir of Shengli Oilfield has a large buried depth and high oil layer temperature.Therefore,the dissolution time of the temporary plugging agent required in water should be 4 h-12 h.In response to these requirements,the paper proposed a method for preparing a temporary plugging agent by polymerizing acrylamide in aqueous solution of amino acid polymer,focusing on the optimization of polymerization conditions,initiator dosage,monomer type,functional additives,reaction temperature and solid content,and established a synthetic process for different performance temporary plugging agents.The medium-grained temporary plugging agent prepared at 90 °C has a dissolution time of 5 h in 120 °C water,and its adhesion performance is good while the residue content is less than 5%.Physical simulation experiments show that the particles with a particle size of 5 mm-8 mm synthesized at 60 °C-90 °C can form a high blocking capacity after a short water absorption,so that the pressure at the injection end rises to about 8 MPa-16 MPa.However,due to the softening and deformation of the particles,the plugging ability of the temporary plugging agent particles at 120 °C is significantly lower than that at 80 °C.Combining particles of different particle sizes can improve the plugging effect.When the temperature rises,the softening and dissolution rate of the temporary plugging agent will be accelerated,the onset time will be shortened,and the plugging effect will be weakened.At this time,the plugging effect should be enhanced by increasing the ratio of temporary plugging agent particles of large particle size and adjusting the temporary plugging agent type.The research of the thesis has guiding significance for the development of high temperature temporary plugging agent.