一种新型抗高温降滤失剂的研究和应用

通过将4-乙烯基吡啶（VP）、N，N-二甲基丙烯酰胺（DMAA）、2-丙烯酰胺-2-甲基丙磺酸（AMPS）、N-乙烯基己内酰胺（NVCL）以过硫酸铵和亚硫酸氢钠作为氧化还原体系进行自由基共聚反应，合成了抗温达260℃的一种新型降滤失剂（PDANV）。通过设计正交实验确定了最优合成条件为:n_DMAA:n_AMPS:n_NVCL:n_VP=6:2:1:1，反应温度为60℃，反应时间为2 h，引发剂质量分数为单体总质量（20%）的0.5%，并利用傅里叶红外光谱（FT-IR）和核磁共振光谱（1H NMR）进一步确定了产物的分子结构。热重分析（TGA）显示PDANV热分解温度在301℃以后，表明其具有良好的热稳定性。同时，将PDANV应用于水基钻井液中，进一步评价其对水基钻井液流变和滤失性能的影响。结果显示，当PDANV加量为2.0%时，水基钻井液的滤失量仅为4.4 mL，260℃老化后滤失量为6.0 mL，高温高压滤失量为24 mL（150℃），同时抗盐至饱和，抗钙20000 mg/L。此外，通过对黏土的粒径分析、SEM分析和Zeta电位分析以及不同浓度的PDANV对黏土颗粒的吸附量的测量，进一步揭示了PDANV在水基钻井液中的降滤失机理。 

Research and Application of a Novel High Temperature Filter Loss Reducer

A novel filter loss reducer PDANV has been developed with monomers such as 4-vinyl pyridine (VP), N, N-dimethyl acrylamide (DMAA), 2-acrylamide-2-methyl propane sulfonic acid (AMPS) and n-vinyl caprolactam (NVCL) through radical polymerization. Ammonium persulfate-sodium bisulfite is used as the redox initiator. The synthesized filter loss reducer can be used at temperatures as high as 260℃. The optimum polymerization conditions as determined by orthogonal experiment are as follows:nDMAA:nAMPS:nNVCL:nVP=6:2:1:1, reaction temperature 60℃, reaction time 2 h, mass of initiator is 0.5% of the total mass of the monomers (20%). The molecular structure of the polymerization product is determined with FT-IR and 1HNMR. TGA result shows that PDANV degrades at 301℃, indicating that it has very good thermal stability. Evaluation of PDANV in a water base drilling fluid shows that, at 2% concentration of PDANV, the filter loss of the drilling fluids is only 4.4 mL, and 6.0 mL after aging the drilling fluid at 260℃. The HTHP filter loss of the same drilling fluid is 24 mL. PDANV is resistant to salt contamination to saturation and calcium contamination to 20,000 mg/L. Analysis clay particle distribution, SEM analysis, Zeta potential analysis, as well as adsorption quantities of PDANV at different concentrations on clay particles further reveal the mechanisms of filter loss reduction of PDANV in water base drilling fluids.