高密度油基钻井液在超深复杂探井中的应用

APPLICATION OF HIGH DENSITY OIL-BASE DRILLING FLUID IN KESHEN WELL 7 OF TARIM OILFIELD

随着勘探的深入,塔里木盆地库车坳陷深井、超深井、特殊井和复杂井不断增加,钻遇地层条件日益复杂,现有水基钻井液已无法满足日益复杂的钻井条件,尤其是在水平井、高温深井、储层保护等方面问题尤为突出。针对上述问题,通过分析研究,认为利用油基钻井液能够圆满解决上述困难。与水基钻井液相比,油基钻井液具有抗高温、抗盐钙侵、利于井壁稳定、降低钻头磨损、润滑性好、低失水和保护储层等多种优点,已成为高难度复杂井安全钻进的重要技术手段之一[1-4]。在塔里木盆地库车坳陷一口完钻井深8 000余米井底温度超过180℃预探井中,采用高密度油基钻井液顺利完成钻井作业,实钻密度达到2.39 g/cm3,HTHP滤失量小于5 mL,切力小于25 Pa,流变性能优良,钻穿膏盐层及储层段时未发生膏盐、CO2,H2S等损害现象,起下钻及下套管作业一次性完成,电测井眼十分规则,充分说明该钻井液体系适合本区块的高温深井勘探开发钻井作业需求。

Keshen well 7 is a exploratory test in the Kuche sag kelasu formation of Tarim oilfield,the drilled well depth is 8023m,bottomhole temperature is over 180℃,the well was drilled successfully by using high density oilbased drilling fluid.The mud density reached 2.39g/cm3,HTHP filter loss was less than 5ml,yield point was less than 25Pa,rheological properties was excellent,and when makeshift through gypsumsalt bed and reservoir section,reservoir hadn't been polluted,tripping and running casing were completed once,borehole was very regular.Application results proved that the drilling fluid was suitable for the drilling requirements of high temperature deep well in the block.