钻井液用核壳式自解堵暂堵剂JZD的合成与性能评价OA

Conventional temporary plugging agents often cause secondary formation damage such as blocking of pore throats in reservoir formations and reduced permeability etc.due to incomplete gel-breaking,delayed unplugging or residues that are difficult to remove,severely restricting the recovery enhancement of oil and gas reservoirs.Developing novel temporary plugging materials with both efficient plugging capacity and self-unplugging capability has become a core research direction and a new idea for technical breakthroughs in the field of oil and gas reservoir protection.Based on the Stöber method,a core-shell self-unplugging temporary plugging agent for drilling fluids was successfully developed using modified poly(butylene adipate-co-terephthalate)as the core and silica as the shell.With core-shell synergistical mechanism,the core of this temporary plugging agent ensures plugging strength,while the shell,with its smart responsive groups,achieves the goal of"strong plugging in the early stage and fast unplugging in the later stage",thus resolving the contradiction of plugging and unplugging.The chemical structure,micromorphology and thermal stability of this temporary plugging agent was systematically characterized using Fourier transform infrared(FT-IR)spectroscopy,field emission scanning electron microscopy(FE-SEM)and simultaneous thermogravimetric-differential thermal analysis(TG-DTA).The results of the characterization show that the temporary plugging agent developed has an obvious core-shell structure.At 120℃and a salinity of 150,000 mg/L,the rate of degradation of the temporary plugging agent reaches 33.62%in 15 days,and it is completely degraded in 36 days,which can meet the requirements of medium-and long-term safe operation.Meanwhile,the temporary plugging agent is well compatible with drilling fluids,it functions normally at temperatures up to 130℃,and is resistant to 25%NaCl environment.Plugging capacity test results show that the plugging depth of sand-bed reduced from 8.5 cm to 1.3 cm as the amount of the temporary plugging agent increases,the plugging efficiency reaches 89.32%,and the percent recovery of permeability is 95.45%,demonstrating both excellent plugging capacity and reservoir protection performance.