Study On High-temperature Resistance Controllable Gel Plugging Technology

Well leakage is one of the complicated conditions that seriously affect the normal drilling process.The particle size distribution of conventional leakage plugging materials is unreasonable,which makes it difficult to enter the leakage channel.After entering the leakage channel,there is no strong viscous resistance,and it is easy to be diluted by formation water,and the plugging success rate is very low.Compared with traditional plugging materials,gel plugging agent has strong deformation ability and viscous resistance,high gelling strength,obvious plugging effect and easy plugging,so it has a broad development prospect.However,conventional gel plugging agent has poor temperature and salt resistance,poor pumpability,and is easy to be diluted by bottomhole fluid.Under high temperature conditions,gel forming time is short and pressure bearing capacity is low,which seriously affects the success rate of gel plugging.In view of the shortcomings and shortcomings of the gel,this paper prepared the anti-high temperature and controllable gel plugging agent by selecting the self-made master agent of anti-high temperature hydrophobic polymerization and combining with hydrolytic polyacrylamide,and by designing a double gel cross-linking system to enhance the gel strength and control the gel gelling time.The preparation conditions of anti-high temperature controllable gel plugging agent were optimized.The effects of the amount of main polymerization agent,the ratio of crosslinking agent and the amount of the additive on the gelation time were analyzed by orthogonal experiment.Through single factor experiment,the influence of the ratio and dosage of polymer master agent on the initial viscosity,gelation time and gel strength of the gel was further analyzed.Finally,the optimal preparation condition range of the anti-high temperature controllable gel plugging agent was obtained.The anti-dilution,temperature resistance and salt resistance properties of anti-high temperature controllable gel plugging agent after gelation were studied.The effects of the gel's glue ratio,shear rate,formation temperature and shear time on the dilution degree were investigated.The effect of heating time on the overall strength of the gel was studied at 120?.The effect of different saline concentration on gel strength was studied to evaluate the salt resistance of gel.In this paper,the sealing performance of anti-high temperature controllable gel plugging agent in porous and fractured simulated formation is systematically evaluated.The effect of pore size,formation temperature and pressure mode on plugging performance of high temperature controllable gel plugging agent was investigated in permeability formation plugging experiment.In the plugging experiment of fractured formation,the plugging effect of different plugging materials on fractured strata with different widths was investigated by means of the combination of gel and inert materials.Two sets of plugging formulas for fractures of 3mm and below were obtained,and the amount of gel was optimized.The gel breaking experiment,acid solubility experiment and reservoir damage experiment were carried out.The self-plugging ability of gel plugging agent and inert material was investigated by adding glue breaker and acidifying fluid,which is beneficial to plugging plugging after plugging of reservoir.Using the core displacement experiment to investigate the damage of broken glue to the reservoir,the damage rate to the high permeability formation is low,which is beneficial to protect the reservoir.