油基钻井液用超支化乳化剂的制备与评价

Preparation and Evaluation of Hyperbranched Emulsifiers for Oil-Based Drilling Fluids

为了提高油基钻井液的乳化稳定性能,以妥尔油脂肪酸、二聚酸、椰油酸甲酯、二乙醇胺、二乙烯三胺、白油等为原料,将脂肪酸上的羧基与多胺的氨基通过脱水反应形成酰胺键,由此产生的多酰胺中心节点将多个脂肪酸分子连接起来,形成功能化的超支化酰胺聚合物,再与白油等复配形成具有“海葵”效应的超支化主乳化剂;以妥尔油脂肪酸、油酸、油酸甲酯、三乙醇胺为原料,制备了辅乳化剂。通过测定固定主辅乳质量比例为4∶1,总加质量为4%,油水体积比为80∶20时的乳状液的微观形态、粒径大小、界面张力、润湿性和稳定性,在4种乳化剂中优选出乳化稳定性能最好的乳化剂。进一步研究乳化剂加量、油水比、温度和密度对所配油基钻井液的影响。结果表明,具有超支化酰胺聚合物的主乳化剂和辅乳化剂复配的乳状液为球形形态,且分布均匀,互不聚集,平均粒径为≤4.5μm,界面张力为≤0.4 mN/m,接触角为≤40°,破乳电压≥400 V;配制的油基钻井液在90~180℃、油水体积比为75∶25~85∶15、密度1.1~1.9 g/cm 3的条件下,老化后流变性能稳定,破乳电压≥800 V,高温高压滤失量≤3 mL,可满足海上高温深井、大位移水平井等复杂井的作业需求。

In order to improve the emulsifying stability of oil-based drilling fluids,tall oil fatty acids,dimeric acids,methyl cocoate,diethanolamine,diethylenetriamine,white oil,etc.are used as raw materials.The carboxyl groups on the fatty acids will form amide bonds with the amino groups of the polyamines through dehydration reactions.The resulting polyamide center nodes connect multiple fatty acid molecules to form functionalized hyperbranched amide polymers,which are then compounded with white oil to form a hyperbranched main emulsifier with a"sea anemone"effect;A co emulsifier was prepared using Tall oil fatty acid,oleic acid,methyl oleate,and triethanolamine as raw materials.By measuring the microstructure,particle size,interfacial tension,wettability,and stability of the emulsion with a fixed main auxiliary emulsion ratio of 4∶1,a total dosage of 4%,and an oil-water ratio of 80:20,the best emulsifier with the best emulsion stability performance was selected among the four emulsifiers.Further study the effects of emulsifier dosage,oil-water ratio,temperature,and density on the formulated oil-based drilling fluid.The results showed that the emulsion composed of main emulsifier and auxiliary emulsifier with hyperbranched amide polymer was spherical in shape,evenly distributed,non aggregating,with an average particle size of≤4.5μm,interface tension of≤0.4 mN/m,contact angle of≤40°,and demulsification voltage of≥400 V;The prepared oil-based drilling fluid has stable rheological properties after aging under conditions of 90~180℃,oil-water ratio of 75∶25~85∶15,and density of 1.1~1.9 g/cm 3.The demulsification voltage is≥800 V,and the high-temperature and high-pressure filtration loss is≤3 mL.It can meet the operational requirements of complex wells such as offshore high-temperature deep wells and large displacement horizontal wells.