强抑制、抗高温防塌钻井液在董8井中的应用

董8井是中石化部署在准噶尔盆地的一口重点预探直井,完钻井深5 580 m,该井上部地层起下钻遇阻频繁,下部侏罗系煤层发育,且地层压力异常,施工中井壁失稳严重;三工河组存在高压盐水层及碳酸氢根流体污染,高密度下钻井液流变性不易调控。针对该井地质特点,通过室内研究,确定使用铝胺强抑制防塌钻井液体系和抗高温成膜防塌钻井液体系,现场应用结果表明,采用的钻井液体系解决了上部地层软泥岩缩径、砂岩段阻卡及侏罗系井壁失稳的难题,全井平均井径扩大率仅为7.02%,满足了施工的需要。

The use of drilling lfuid te of strong inhibition,anti-high temperature and anti-collapse in Well Dong-8

Well Dong-8 is an important exploratory vertical well placed in Junggar Basin by SINOPEC. Its total depth is 5 580 m. Tight hole was frequently met during tripping in the upper part of the well, and in the lower part, the Jurassic coalbeds were deposited. Moreover, the formation pressure was anomalous and wellbore instability was severe during drilling. The Sangonghe Formation has high-pressure saltwater layers and is contaminated by bicarbonate fluid, so the rheology of drilling fluid under high density is not easily controlled. In view of its geologic characteristics and through indoor studies, it was determined that the aluminum-amine strong inhibition and anti-sloughing drilling fluid system and high-temperature film forming anti-sloughing drilling fluid system are used. Field application results show that the drilling fluid systems used have overcome the difficulties of tight hole in the upper soft mudstone, sticking in sandstone section and instability of Jurassic wellbore. The average enlargement rate of the entire hole was only 7.02%, which was quite satisfactory.