低密度钻井液在沈289井的应用

The Application of a Low-density Drilling Fluid in Well Shen 289

沈289井是大民屯凹陷前进-东胜堡西侧潜山带沈34-沈119东块上的一口预探井,三开实施欠平衡钻井技术。由于潜山油层压力系数仅为0.93,因此必须使用超低密度钻井液。选用了水包油中空玻璃微珠钻井液,对其配方进行了优选并评价了其性能。该钻井液密度可以达到0.83 g/cm3,抗温可达150℃。通过应用该钻井液,该井三开施工中一直处于点火燃烧状态,发现了良好的油气显示,为重新认识和评价潜山构造提供了重要依据,而且钻井速度大大提高。指出,该钻井液适用于在井壁比较稳定的地层实施的欠平衡钻井,同时中空玻璃微珠随着水眼喷射剪切和钻具的研磨会发生破碎,使钻井液密度逐步上升的问题尚待解决。

Well Shen 289 is an exploration well located on a buried hill structure,of which the third interval was drilled using under-balanced drilling technology,that is,a low density mud had to be used because of the low formation pressure(pressure gradient 0.93) in the buried hill reservoir.An oil in water(O/W) emulsion treated with hollow glass beads with a density as low as 0.83 g/cm3 was selected.This mud had a temperature stability of 150 ℃.Very good oil shows were found during the drilling in the third interval.The use of the light mud presented a new understanding and evaluation of the buried hill structure and rate of penetration was thus greatly increased.It is pointed out that this technology is suited for use in stable formations.