次氯酸钠催化交联的非水解聚丙烯酰胺微凝胶的研制

Preparation of Aqueous Microgel on Non-Hydrolyzed Polyacrylamide Catalytically Crosslinked by Sodium Hypochlorite

在次氯酸钠作用下水溶液中非水解聚丙烯酰胺的酰胺基经由异氰酸酯基转变为氨基 ,后二种基团反应生成二价碳酰二胺基 ,将聚合物分子交联而形成水基凝胶。将次氯酸钠用量与使一半酰胺基转变为氨基所需的次氯酸钠量之比定为交联度。实验微凝胶由 6 g/LPAM水溶液形成的凝胶稀释而成。配液用水有清水 (自来水 )、盐水 (2g/LNaCl水溶液 )和高矿化水 (矿化度 80 g/L ,含Ca2 + 、Mg2 + 各 1g/L)。用红外光谱表征了交联聚合物的结构。当PAM浓度为 2 g/L ,交联度为 11.4 %时 ,在宽剪切速率范围内清水微凝胶的粘度低于而盐水微凝胶的粘度则高于相应的 2 g/LHPAM溶液 ,高矿化水微凝胶 7s-1下的粘度 ,2 0℃时略低于而 4 5℃和 6 0℃时则高于清水微凝胶。在渗透率～ 1μm2 的填砂模型上 ,注入～ 0 .3PV的PAM浓度 1.0～ 3.0 g/L、交联度 11.4 %的微凝胶 ,在水驱基础上清水微凝胶提高采收率的幅度随PAM浓度增大而增大 (17.6 %～ 2 4 .2 %) ,盐水微凝胶在PAM浓度为 1.5 g/L时提高采收率的幅度最大 (2 5 .3%)。用于驱油的PAM微凝胶的最佳交联度为 11.4 %,PAM浓度为 2 .0 g/L时粘度为 2 1.0mPa·s ,在水驱基础上提高采收率 2 2 .3%。图 4表 3参 5。

The amide groups of non hydrolyzed PAM in aqueous solution are changed through isocyanate to amino groups at the presence of NaClO and the later 2 groups react to form bivalent carbamide group and thus crosslink PAM molecules and convert the solution to gel. The degree of crosslinking, D c, is determined as ratio of hypochlorite added to that needed to change half of all amide groups to amino groups. The experimental microgel is prepared by diluting 6 g/L gelled PAM solution in fresh and salt (2 g/L NaCl solution) water and in brine of TSD= 80 g/L and containing 1 g/L Ca 2+ and 1 g/L Mg 2+ . The structure of the crosslinked polymer is identified by IR. With PAM concentration 2 g/L and D c 11.4% the microgel in fresh water has viscosity lower and the microgel in salt waer - higher than coresponding 2 g/L HPAM solutions do in wide shear rate range; the viscosity of microgel in brine at 7 s -1 is slightly lower at 20℃ and higher at 45℃ and 60℃ than that in salt water. On sand packs of permeability ～1 μm 2 after water flood, injecting ～0.3 PV of microgel of PAM concentration 1-3 g/L and D c 11.4% leads to enhancement in oil recovery increased with increasing PAM concentraton in the case of the microgel in fresh water and to maximal enhancement at PAM concentration 1.5 g/L in the case of the microgel in salt water. For microgel in salt water to be used in EOR, the optimal D c is of 11.4%, the viscosity is of 21.0 mPa·s when PAM concentration being of 2 g/L and enhancement in oil recovery of 22.3% is observed with the microgel.