一种固井用腐植酸-AMPS/DMAM/FA接枝共聚物降失水剂

采用自由基聚合法将AMPS、N，N-二甲基丙烯酰胺（DMAM）、反丁烯二酸（FA）进行接枝共聚，在AMPS∶DMAM∶FA为1∶0.38∶0.08，单体总量与腐值酸钠的质量比为1∶0.2、引发温度为60℃，单体溶液的pH为7的条件下，合成了一种抗高温油井水泥降失水剂G85L，为黑色黏稠液体，固含量为20%。通过单体残留分析与红外表征证明了合成产物为接枝共聚物，并通过热重分析证明该产品抗温达265℃。参考API RP 10B-2 2013进行实验，评价了该产品在水泥浆中的各项性能，结果表明，该产品不仅在中低温有较好的控制失水能力，当加量为4%时可以将API失水量降至40 mL，而且在高温条件下也具有较强的控制失水能力，200℃下失水量可以控制在50 mL以内，并且对水泥浆的稠化时间、抗压强度无副作用，与多种水泥浆体系配伍性好，是一种普适性优良的抗高温产品。 

AMPS/DMAM/FA-A Graft Copolymer Humic Acid Fluid Loss Reducer for Well Cementing

A high temperature cement slurry fluid loss reducer, G85L, was synthesized with 2-acrylamido-2-methyl propane sulfonic acid (AMPS), N,N-dimethylacrylamide (DMAM) and fumaric acid (FA) through radical polymerization under the following conditions:AMPS:DMAM:FA=1:0.38:0.08, mass ratio of total monomers to sodium humate=1:0.2, initiation temperature 60℃, and pH (of the monomer solution)=7. G85L was a viscous black liquid containing 20% solids. Analysis of the residual monomers and IR characterization showed that the synthesized product was a graft copolymer, and thermogravimetric analysis indicted that the property of the G85L remained stable at 265℃. Filtration experiment (done in accordance with API RP 10B-2 2013) demonstrated that addition of 4%G85L reduced filter loss of cement slurry to 40 mL at low temperatures, and to less than 50 mL at 200℃. No evidences of side effect of G85L on the thickening time and compressive strength of cement slurry have been observed during experiments. G85L shows good compatibility with many cement slurry formulations and is a universal high temperature filter loss reducer for cement slurries.