中江地区井壁失稳机理及对策研究

川西中江构造地层情况复杂，该区块多口井在钻井过程中都出现了严重的井壁失稳，这制约了对该区块的油气勘探开发速度。针对这一情况，文章对中江构造泥页岩的稳定性进行了大量的研究，并从失稳机理入手进行适合该区块钻井液体系的研究，在室内实验的基础上优选出了适合该地区地层钻进的钻井液体系--钾钙基聚磺防塌钻井液。通过现场试验，证明该钻井液体系能有效控制该区的井壁失稳，大幅度降低井下复杂情况的发生。

MECHANISM AND COUNTERMEASURES OF BOREHOLE INSTABILITY IN ZHONGJIANG AREA 1)

The stratigraphy is complicated in Zhongjiang structure of west Sichuan. The severe borehole instability happens in the drilling process for several wells of the block, which restricts the velocity of oil/gas exploration and development in the block. According to the situation, a lot of researches are conducted for the stability of shale rocks in Zhongjiang structure. Based on the mechanism of the instability, the drilling fluids are studied to meet the requirements of drilling in the block. With in-house experiments, the drilling fluids system fitting the area is optimized. It is poly-sulfaphane drilling fluid with instability control. By field tests, it is proved the drilling fluid can control the borehole instability effectively and decrease the complex cases happening during drilling.