Preparation of A 240 ℃ Cement Slurry Filter Loss Reducer Prepared through Thermal Initiation Polymerization

A terpolymer cement slurry filter loss reducer HTFLA-A is developed to deal with the poor thermal stability of the cement slurry filter loss reducers presently in use. HTFLA-A is designed and synthesized through high temperature thermally induced polymerization instead of the conventional water solution initiation polymerization. HTFLA-A works normally at temperatures up to 240 ℃. The optimal synthesis condition of HTFLA-A is: mass ratio of water to the monomers is 1:1, reaction temperature is 150 ℃, pH of the reaction system is 9, and the reaction time is 32 h. The molecular structure of HTFLA-A is characterized with FT-IR, DSC/TGA and NMR. The results of the study show that the final synthesis product HTFLA-A is the expected product. Weight loss on heating of HTFLA-A at 439 ℃ is only 23.80%. The reason for this low weight loss on heating is because in the high temperature synthesis, the unstable structures in the monomer molecules and the by-products of the synthesis process are all removed from the final product, thus improving the high temperature stability of the target product. Performance evaluation of HTFLA-A shows that at a concentration of 1.2%, HTFLA-A can control the API filtration rate of a cement slurry to below 50 mL at test condition of 180-240 ℃ and 6.9 MPa.