疏水改性低分子量阳离子聚丙烯酰胺抑制剂的制备及性能评价

Synthesis and Performance Evaluation of Hydrophobically Modified Low Molecular Weight Cationic Poly(acrylamide) Shale Inhibitor

针对现有阳离子类抑制剂与钻井液配伍性、抑制性较差的不足,本文以丙烯酰胺、甲基丙烯酰氧乙基三甲基氯化铵、丙烯酸十八酯为原料,以乙醇和乙酸丁酯的混合物作溶剂,采用沉淀聚合法,制备出了疏水改性低分子量阳离子聚丙烯酰胺BJX-1页岩抑制剂。通过研究不同反应条件对BJX-1分子量的影响规律,得出溶剂组成对BJX-1分子量影响最大,可通过调节溶剂组成实现BJX-1分子量的控制。当分子量为1.45×10~5g/mol^1.87×10~5g/mol时,BJX-1的抑制性最好,页岩岩屑120℃热滚回收率约为78%;增加BJX-1中疏水结构单元含量至2%~4%时,可进一步提高BJX-1抑制性,使页岩岩屑120℃热滚回收率高于90%;此时的最佳反应条件为:以乙醇和乙酸丁酯按体积比90∶10~100∶0组成的混合物作为溶剂,引发剂质量分数为0.1%,单体质量分数为3%,在80℃下反应7h。通过对比研究发现,当加量为1%时,BJX-1所对应的页岩岩屑120℃热滚回收率分别比常用小分子阳离子化合物JA-1和高分子量阳离子聚合物DY-1高27.85%和50.06%。BJX-1更能提高钻井液的综合流变性能,使钻井液流变性更加稳定,而且具有优良的高温高压降滤失性。

In order to overcome the low shale inhibition property and poor compatibility of the present cationic shale inhibitors,a low molecular weight cationic poly （acrylamide） with hydrophobic modification structures,i.e.,BJX-1,was prepared by precipitation polymerization in ethanol/butyl acetate mixtures.Acrylamide,methacryloxyethyl trimethylammonium chloride,and octadecyl acrylate were selected as the monomers.The factors,such as solvent composition,temperature,initiator concentration,which influence the molecular weight of BJX-1 were studied;the results show that the molecular weight of BJX-1 is significantly influenced by solvent composition,thus the molecular weight of BJX-1 can be adjusted by changing solvent composition;the best shale inhibition result can be achieved by keeping the molecular weight of BJX-1 at 1.45 × 105g/mol～ 1.87 × 105g/mol,the rolling recovery of shale cuttings at 120℃ is about 78%.The rolling recovery of shale cuttings at 120 ℃ could be more than 90% when increases the content of hydrophobic units in BJX-1 to 2～4%.The optimum reaction conditions are：Vethanol ∶ V butyl acetate =90∶10～ 100∶0,0.1% of initiator,3% of monomer,reaction temperature is 80℃,reaction time is 7h.A comparative study on the performances of BJX-1 and the present cationic shale inhibitors in drilling fluids was conducted,the results show that when keep the shale inhibitor addition at 1%,the rolling recovery of shale cuttings at 120℃ of BJX-1 is 27.85% and 50.06% more than the most commonly used cationic compound JA-1 and cationic polymer DY-1.The results indicate that BJX-1 can improve the rheological properties of drilling fluid and make the rheological properties of drilling fluid more stable;BJX-1 can also show good HTHP fluid loss control capability.