Effect of poly(AMPS/DMAA/IA/SSS) intercalated Mg/Al layered double hydroxides on reducing fluid loss at 240? and improving early strength of oil well cement

Fluid loss agent (FLA) was adopted to reduce the fluid loss of cement paste to ensure the safety of cementing construction. With the increase of exploration depth, FLA applied at high temperatures has been urgently required. To meet the cementing requirements at 240 ?, the FLA with organic/inorganic intercalated micro-structure was prepared. Anionic polymer FLA (ADIS) was comprised of 2-acrylamido-2-methylpropane sulfonic Acid (AMPS), N, N-dimethylacrylamide (DMAA), Itaconic acid (IA) and Sodium p-styrene sulfonate (SSS). The organic-inorganic hybrid FLA (MgAl-ADIS-LDH) was prepared via intercalating ADIS into Mg/Al hydrotalcite (MgAl-NO3-LDH) interlayers. The intercalated microstructure was observed by SEM, TG results exhibited that the intercalation of polymer ADIS in MgAl-NO3-LDH enhanced the thermal stability of overall FLA. When applied in cement, the cement with MgAl-ADIS-LDH showed a small water loss of 36 mL at 240 ?. Moreover, the structure avoided the decrease in the compressive strength of hardened cement resulted from traditional polymer FLA. Compared with the cement contains 1.6% bwoc ADIS, the compressive strength of specimen with MgAl-ADIS-LDH increased by 20.5% after cured for 3 days.