An amphoteric polymer sulfonate drilling fluid was designed for use in Kenkyak to drill the sub-salt reservoirs characteristic of high pressure and high temperature. Field application showed that this high density mud had good rheology, and slat formation drilling was done successfully. Down hole troubles pre-viously encountered were greatly minimized. Average percent borehole overcut was only 5.62%. Highest drag encountered during POOH was less than 10 tons. In drilling Well Kenkyak-8102, drilling fluid theol-ogy was greatly optimized and was lower than that of the mud used in the adjacent well 235. Marsh funnel viscosity of a mud with a density of 1.95 g/cm<'3> can be kept between 70 and 90 sec.%为解决肯基亚克盐下油田压力高、温度高、矿化度高、密度高等钻井液技术问题,在对该地层特性、岩性和储层特点进行研究的基础上,研发出了适合该区域的两性离子聚磺盐水钻井液.现场应用表明,该钻井液较好地解决了高密度盐水钻井液流变性、盐层井壁稳定、漏喷同层和高密度盐水钻井液的防卡等问题,实现了全井无事故及复杂情况的记录;井径规则,平均井径扩大率为5.62%;润滑防卡措施效果明显,起钻最大提升阻力不超过10t,无任何阻卡情况.肯基亚克8102井钻井液的流变性得到明显优化,流变参数显著降低,与未采用该技术的邻井235井相比,表观黏度降低42%,塑性黏度降低40%,动切力降低46%,静切力降低58%,可将密度为1.95 g/cm<'3>的钻井液的黏度维持为70～90 s.
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