以季戊四醇为支化剂合成低黏度高切力钻井液提切剂

针对目前水基钻井液常用的提切剂普遍存在黏度增加幅度大于切力增加幅度的缺点，以季戊四醇为支化剂，硝酸铈铵为引发剂，引发丙烯酰胺、2-丙烯酰胺-2-甲基丙磺酸与4-乙烯基-1-（3-磺丙基）吡啶内嗡盐（4-VPPS）共聚，合成出低黏度高切力钻井液用提切剂PAAVP，并考察了合成条件对该聚合物黏度和切力的影响。聚合体系中引入季戊四醇后其表观黏度降低，动塑比提高，优选季戊四醇加量为单体质量的2.5%～3.0%。4-VPPS有利于提高聚合物抗温抗盐性，优选在聚合单体中占比为6%～10%。引发剂加量为单体质量的0.0275%～0.03%。按照推荐配比合成出的聚合物PAAVP的1%水溶液表观黏度为27 mPa·s，动塑比为1.45 Pa/mPa·s。PAAVP溶液在150℃热滚后仍能保持74%的黏度和54%的动塑比值，比常规提切处理剂黄原胶具有更好的抗温性。PAAVP在5% NaCl溶液中能保持91%的黏度和85%的动塑比值，作为钻井液低黏提切剂有较大的应用潜力。

A Drilling Fluid Gelling Agent Synthesized with Pentaerythritol as Branching Agent

When using gelling agents to increase the gel strengths of water base drilling fluids, it was found that the increase of gel strengths was generally smaller than the increase of viscosity. A low viscosity high gel strength additive PAAVP has been developed to deal with this problem. PAAVP was prepared by the copolymerization of acrylamide (AM), 2-acrylamide-2-methylpropane sulfonic acid (AMPS) and 4-vinyl-1-(3-sulfopropyl) pyridinium salt (4-VPPS) using pentaerythritol as branching agent and cerium ammonium nitrate as initiator. The effects of copolymerization conditions on the viscosity and gel strengths of PAAVP was studied. Introduction of pentaerythritol into the copolymerization system reduced its apparent viscosity and increased its ratio of yield point to plastic viscosity (YP/PV). The optimum concentration of pentaerythritol was determined to be 2.5%-3.0% (mass) of the monomers for the copolymerization. 4-VPPS is beneficial to the thermal stability and salt resistance of the final product, and its concentration in the copolymerization system was 6%-10% (mass) of the monomers. The concentration of the initiator was 0.0275%-0.03% (mass) of the monomers. 1% water solution of the PAAVP produced in accordance with the recommended mass ratio of reactants had apparent viscosity of 27 mPa·s and YP/PV value of 1.45 Pa/mPa·s. The solution, after hot rolling at 150℃, still had 74% of its original apparent viscosity and 54% of its original YP/PV value, showing better thermal stability than xanthan gum. PAAVP dissolved in 5% NaCl solution had 91% of its original apparent viscosity and 85% of its original YP/PV value, demonstrating potential for future application.