抗高温低密度水包油钻井液在梨深1井的应用

The Application of a High Temperature Low Density Oil-in-Water Drilling Fluid in Well Lishen-1

针对梨深1井目的层营城组和沙河子组地层压力梯度较低（为0.94-0.98）,选用了低密度水包油钻井液进行欠平衡钻进,密度为0.89-0.91 g/cm3。该井从井深3 799.33 m点火成功,到井深4 368.5 m完钻,实现全井段边喷边钻,共发现13个气层,厚度为26 m,最高气流量达3 326 m3/h。水包油钻井液具有井底负压值波动小、高温稳定性强、密度可调范围广、防塌和润滑效果好,对油气层污染小等优点。在温度达到160℃,油水比高达70∶30的情况下,没有出现油水分层现象。该井欠平衡钻进868.5 m、泥页岩浸泡69 d,没有发生井壁垮塌现象,平均井径扩大率为9.3%,达到了负压钻井的目的。

The target zones of Well Lishen-1,Yingcheng Formation and Shahezi Formation,both have low formation pressure gradient(0.94～0.98).A low density(0.89～0.91 g/cm3) oil-in-water drilling fluid was chosen to drill the reservoir in underbalanced mode.This paper discusses the formulation optimization and maintenance of the high temperature low density oil-in-water drilling fluid.Using this fluid,the bottom hole pressure was not fluctuating in a wide range.At high temperature of 160 ℃,and oil/water ratio of 70∶30,the oil was still well emulsified in water.The shale formation in this well had been rinsed for 69 d,and no borehole sloughing and caving were observed.Hole diameter enlargement was only 9.3%.The well was successfully fired at well depth of 3,799.33 m and completed at well depth of 4,368.5 m.The well was drilled while blowout.Thirteen gas zones(totally 26 m in thickness) were found,with the highest production rate of 3,326 m3/h.