摘 要：在钻井工程中，钻遇地层的75%以上是泥页岩地层，而由它引起的井眼不稳定问题超过了90%。总结井壁稳定性研究现状，了解页岩膨胀机理，从钻井液的不同pH值和不同矿化度两个性能的角度分析对泥页岩的抑制能力。由于井壁稳定问题是一个复杂的世界性难题，它涉及到多学科领域，受多种主、客观因素的影响，所以本文在不考虑力学和温度压力效应的情况下仅从化学角度对苏北区块地层的井壁稳定性问题作一简单探讨。由于泥页岩中含有水敏性黏土矿物，与钻井液接触时，泥页岩与钻井液相互作用，产生水化膨胀。通过页岩膨胀实验得出不同矿化度和不同pH值对页岩膨胀的抑制效果，总结实验结果，得出氢氧根明显促进泥页岩中粘土水化分散。氯化钠和氯化钾都是随着浓度的增加而对页岩的抑制性增强。浓度在2%-10%氯化钙溶液的页岩膨胀量差别不大，但随着浓度的进一步增大抑制性会有明显的提高。
关键词：井壁稳定性；页岩膨胀；钻井液性能；pH值；矿化度
Abstract：In drilling engineering, 75% of the drilled formation is a shale formation, wellbore instability problems caused by it are more than 90%. Summary the research status of the wellbore stability ,and shale expansion mechanism,from the perspective of drilling fluids of different pH values and different degree of mineralization analysis the shale inhibition.Wellbore stability problems is a complex worldwide problem,it involves a multidisciplinary field and influenced by a variety of main objective factors,so this paper without considering mechanics and temperature and pressure effect ,only considering chemical ,take a simple discussion about the wellbore stability from the Angle of northern jiangsu province. Due to shale contains water-sensitive clay minerals and when it contacts with drilling fluids, shale and drilling fluids interact and lead to hydration expansion. Through the shale inflation experiment, it indicates that the effect of different salinities and different pH value on the shale inhibitory. The experimental results obtained hydroxide was the promotion of hydration of shale clay dispersion. The higher the concentration of sodium chloride and potassium chloride,the stronger inhibition of shale. Concentration of 2% -10% calcium chloride solution of shale expansion is not very different, but as the concentration further increased, suppression will be significantly improved.
Key words: wellbore stability; Shale expansion; fluid property; pH value; mineralization degree
