Ammonium hydrolyzed polyacrylonitrile (NH4-HPAN) is a drilling fluid additive usually used in drilling fluids. However, NH4-HPAN and cement slurry have poor chemical compatibility. When they come into contact with each other, cement slurry can be contaminated, which damages the cementing quality and causes downhole emergency. This paper studies the effects of NH4-HPAN on the properties of cement slurry, such as thickening time, rheological properties, and compressive strength. This paper combines atomic absorption spectrophotometer, zeta probe potentiostat, and environmental scanning electron microscope (ESEM) to explore the NH4-HPAN contamination mechanism in cement slurry. The experimental results show that NH4-HPAN decreases the zeta potential of cement slurry and reduces the electrical property of cement particle surfaces, which causes particles agglomeration. Moreover, NH4-HPAN reacts with cement slurry to generate a netlike cross-linked structure that changes the microstructure of cement slurry and agglomerates cement particles to increase the movement resistance of cement particles. Finally, the rheological properties and thickening time of cement slurry are deteriorated, and the netlike cross-linked structure is adsorbed on the cement particles surfaces, which reduces the rate of hydration reaction and decreases the compressive strength of cement stone. They seriously endanger the safety operation and cementing quality.
|Number of pages||6|
|Journal||Journal of Materials in Civil Engineering|
|Publication status||Published - 1 Sep 2017|
- Ammonium hydrolyzed polyacrylonitrile (NH4-HPAN)
- Cement slurry
- Cementing displacement
- Compressive strength