Synthesis and Properties of an Early-Strength Retarder Based on AMPS

With the increase in the depth of oil and gas exploitation, the temperature gradient in the long cementing section becomes increasingly larger. To ensure the safe pumping of cement slurries, a large amount of oil well cement retarder needs to be added, resulting in problems such as super-retardation and slow strength development of the cement slurries in the low-temperature section at the wellhead, which in turn seriously affecting the quality and safety of cementing operations. To deal with these problems, a high-temperature resistant and early-strength type retarder AMND was synthesized with four monomers, namely AMPS, MA, NVP and DEAA, based on the adsorption theory. The molecular structure and performance of the retarder were tested by methods such as infrared spectroscopy, thermal stability testing, gel permeation chromatography analysis and high temperature and high pressure thickening. The test results show that: 1) the retarder AMND has excellent thickening performance at high temperatures; the thickening time of the cement slurry can reach 316 minutes at 150℃, 2) AMND has excellent setting control performance, as well as low temperature sensitivity and dosage sensitivity. It can adjust the thickening time in different temperature ranges, which is beneficial to the safe pumping of the cement slurry at the well site, 3) it has little impact on the mechanical development of the set cement. At a circulating temperature of 150℃ and a curing temperature of 60℃, the strengths of the set cement at 1 day, 2 days, and 3 days can reach 6.34 MPa, 8.24 MPa, and 14.66 MPa respectively, satisfying the strength requirements for cementing operations. The conclusion is that this retarder can alleviate the super-retardation phenomenon in the low-temperature condition, achieve retardation at high bottom hole temperatures, and does not affect the development of the strength of the cement at the wellhead. It has successfully mitigated the super-retardation or non-setting problems in wells with large temperature differences and long cementing sections, and has a very good application prospect.