Retarder design for long open-hole well cementing through the interfacial adsorption

Abstract

In the long open-hole section well-cementing, cementing fluids frequently lose their effectiveness because of high temperature and slow development of the strength of the top cement slurry. In the present study, this problem has been addressed with the high temperature polymer retarder (HTX-1) based on interfacial adsorption because the cement slurries can be characterized as colloidal suspensions. The HTX-1 was characterized through Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and thermogravimetric analysis (TGA). Then, the performance of the HTX-1in the cement slurry was evaluated in our laboratory. It was found that the molecular structure of the designed HTX-1 by FTIR and MNR spectroscopy contain the characteristic functional groups of the four monomers. The HTX-1 has only 4.5% mass loss when the temperature is less than 332 ℃. The concentration sensitivity coefficient of the HTX-1 is in the range of 0.48～1.73, and the maximum temperature sensitivity coefficient of the HTX-1 is 6.2%. The 24 h compressive strength of the top cement column at temperatures between 60 ℃ and 100 ℃ is at least 10.6 MPa. This experimental investigation shows that the new retarder has high temperature resistance, low sensitivity and wide application range of temperature. The thickening time of cement slurry can be adjusted while meeting the required strength of top section in deeper wells through changing addition amount of the HTX-1.