Preparation and application of self-emulsifying curing agent for CO2 high-pressure corrosion-resistant resin cement

In order to solve the problem that oily epoxy resin is not easy to disperse in a cement slurry system and its application is limited due to low stability, a new self-emulsifying curing agent ETB for oilfield cement slurry was prepared by using bisphenol F-type glycidyl ether (BPF), tetraethylenepentamine (TEP) and epoxypropyl tri-methyl ammonium chloride (EPTAC) in three steps. The optimized synthesis conditions are n (TEP): n (BPF)= 2.6:1, 65 degrees C addition reaction for 4 h, n (EPTAC): n (TEP)= 1:1, and 75 degrees C for 2 h end-capping reaction. Finally, 20% glacial acetic acid is added for 30 min salt reaction to obtain the self-emulsifying curing agent ETB. The target product was obtained through Fourier transform infrared spectroscopy and nuclear magnetic resonance analysis. The stability shows that BPF resin lotion is uniform and stable compared to other lotions, with an average particle size of 580.9 nm. The application study of ETB emulsified BPF resin lotion shows that when the dosage is 6.0%, the fluidity index n of the resin cement slurry system is 0.887, the consistency coefficient K is 0.178 Pa.sn, the rheological property is good, the high-temperature and high-pressure water loss can be controlled within 50 mL, and the 48 h compressive strength increases by 36.05% compared with the blank cement paste. The high-pressure CO2 corrosion experiment shows that the penetration growth rate of resin cement stone is -0.168%, which is much lower than the 455.6% of blank cement stone. Before and after corrosion, the compressive strength decline rate of blank cement stone is 25.07%, while the decline rate of resin cement stone is only 2.18%, indicating that resin cement stone has good corrosion resistance. TG-DTG and SEM were used to analyze the corrosion resistance mechanism: the BPF resin lotion was crosslinked and solidified in the cement slurry to form a film, and was tightly filled inside to form a three-dimensional network structure, thus improving the corrosion resistance.

Automated summary

By using a specific curing agent ETB, the problem of dispersion and stability for oily epoxy resin in cement slurry system has been successfully solved. The application of the emulsified curing agent ETB in oilfield cement slurry system shows good rheological performance, resistance to high temperature and high pressure water loss, and corrosion resistance.