Oil-in-water emulsion drilling fluid is an important low-density water base drilling fluid and is widely used in drilling low-pressure reservoirs.To enhance the high temperature stability of the oil-in-water emulsion drilling fluid in deep well drilling,a sulfonated betaine with varied carbon chains was synthesized in laboratory and used in formulating emulsion drilling fluid after measuringthe change of its surface characteristics.Experimental results showed that the drilling fluid formulated had excellent rheology and good emulsion stability.After hot rolling at 180-210 ℃ for 16 hours,the viscosity and gel strengths of the drilling fluid were maintained in reasonable ranges.HTHP filter loss was less than 20 mL,satisfying the basic requirements as an emulsion drilling fluid.No oil separation and emulsification were found of the drilling fluid.The drilling fluid was resistant to contamination caused by 15％ water,15％ diesel oil,15％ drilled cuttings,or by 2％ salt,respectively,indicating that it was able to satisfy the needs for deep low pressure reservoir drilling.%水包油乳化钻井液作为一种重要的低密度水基钻井液体系,在低压油气层钻探中有着较为广泛的应用,针对目前该体系在深部地层使用过程中出现的抗温能力不足的问题,室内通过一步反应合成了不同碳链数的磺基甜菜碱,测定了其在高温处理后的表面性能变化情况,并将其引入水包油乳化钻井液中.实验结果表明,配制得到的钻井液性能良好,乳化稳定性好,在经过180～210℃热滚动16h后,体系黏度、切力仍处于合理范围,高温高压滤失量均小于20mL,满足基本要求;体系稳定性较好,无析油破乳现象发生;且具备一定的抗污染能力,抗水污染达15％,抗柴油污染达I5％,抗钻屑污染达15％,抗盐污染达2％,因而能够满足深部低压油气层钻井的要求.
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