基于疏水缔合聚合物的新型钻井液封堵剂

A new type plugging agent for drilling fluid based on hydrophobic associative polymer

针对常规封堵剂难以对非均质渗透性储层实现有效封堵的难题,基于疏水缔合聚合物的缔合理论,采用共溶剂聚合法,经分子结构优化设计,合成了新型的丙烯酰胺(AM)/十八烷基二甲基烯丙基氯化铵(C18DMAAC)/丙烯酸钠(AANa)疏水缔合共聚物(HMP),采用红外光谱、元素分析和凝胶色谱表征和测定了HMP的分子结构和分子量,并对其作为钻井液封堵剂的可行性进行了探讨。结果表明,新型疏水缔合聚合物HMP的重均分子量小于10万,对钻井液的流变性能影响小,当HMP分子中疏水单体C18DMAAC摩尔含量达到0.66%,且HMP在钻井液中的质量浓度达到0.6%后,其具有优良的封堵性能,在高温高压条件下可以实现对石英砂床和不同渗透率岩心的有效封堵,且形成的封堵层薄而致密;粒度分布测定结果表明,HMP将钻井液体系的粒度分布范围拓宽至几微米到几百微米,并能显著增大体系的平均粒径,这是其具有优良封堵性能的主要原因。

In view of the problem that conventional plugging agent cannot realize effective plugging to heterogeneous permeablereservoirs, based on the association theory of hydrophobic associative polymers and using the method of polycondensation in a solventand through molecular structure optimization design, a new type of hydrophobic associative polymer （HMP） was synthesized ofacrylamide （AM）/octadecyl dimethyl allyl ammonium chloride （C18DMAAC）/acrylic acid sodium （AANa）. The infrared spectrum,element analysis and gel chromatography were used to represent and measure the molecular structure and molecular weight of HMP,and it’s feasibility of being the drilling fluid plugging agent was discussed in this paper. Results show that the weight-average molecularweight of the new type of hydrophobic associative polymer （HMP） was less than 100 000, which had small influence on the rheologicalproperties of drilling fluid. When molar content in hydrophobic monomer C18DMAAC in HMP molecules was up to 0.66% and the massconcentration of HMP in drilling fluid was up to 0.6%, then it would have excellent sealing performance, and can realize effective sealingof quartz sand bed and cores of different permeability under the condition of high temperature and high pressure and the resulting sealinglayer was thin and tight. Results of particle size distribution measurement show that HMP broadens the scope of particle size distributionof drilling fluid system to a few microns to a few hundred microns, and can significantly increase the average particle size of the system.This is the main reason for its good sealing performance.