Amphoteric retarder for long-standing cementing: Preparation, properties and working mechanism

Abstract

Amphoteric retarder (AIDA) was prepared by radical copolymerization of 2-acrylamido-2-methyl propane sulfonic acid (AMPS), itaconic acid (IA), 2-(Methacryloyloxy) ethyltrimethylammonium chloride (DMC) and methyl allyl polyethenoxy ether (TPEG). The characteristics of AIDA were verified by FTIR and 1HNMR. In addition, the performances of AIDA in cement slurry including thickening time, compressive strength developments, and adaptability to long standing cementing with lager temperature differences were investigated. The results indicated that AIDA possessed excellent temperature-resistance (180 °C) and good adaptability to long standing cementing with larger temperature differences of 90 °C. Finally, the retarding mechanism of AIDA was revealed through transverse relaxation time (T2) distribution, XRD tests, and adsorption behavior of AIDA on cement particles. The results demonstrated that the stronger retarding effect of AIDA originated from the dual adsorption of AIDA on cement particles compared with AMPS-IA copolymer (PAI). AIDA outperformed PAI in its adaptability to long-term cementing, which was responsible to (a): the adsorbed amount of AIDA at higher temperature is higher than that of lower temperatures, therefore, AIDA has a stronger retarding effect at higher temperature and weaker retarding effect at lower temperature. (b) Compared to PAI, the adsorption strength of AIDA is weaker and easy to de-adsorb, so both the retarding effect and the hydration reaction of cement are realized. Thus, the super-retarding phenomenon of cement slurry containing AIDA is effectively prevented.