Synthesis and evaluation of a new type of oil-well cement temperature-resistant retarder

The retarder citric acid used in oil well cement has the disadvantages of sensitive dosage and low early strength. In order to overcome this disadvantage, citric acid was used as chelating agent, metal nitrate and ethylene glycol were selected as reactant materials, and an orthogonal test was used to synthesize a new metal chelate-type retarder in this paper. The experimental results show that the optimum conditions for MCR synthesis are: mass ratio of Ca/Al/Fe nitrates of 14:3:1, reaction temperature of 60 degrees C, and reaction time of 12 h. MCR is temperature resistant, and can easily control the thickening time and has less impact on the compressive strength of cement slurry. The 7 days strength of cement slurry with MCR exceeded 22 MPa, which also meets the construction requirements. In addition, combined X-ray diffraction and thermogravimetric analyses to elucidate the retardation mechanism of MCR show that MCR effectively inhibits the formation and growth of Ca(OH)(2) crystals in the early stage of cement hydration.