实验分析泥岩水化膨胀应力与力学参数之间的关系

在钻井的过程中,泥页岩地层一旦与水基钻井液接触后,便会发生水化膨胀作用,在地层压力和上覆岩层压力的约束下产生膨胀应力,岩石强度降低,井壁稳定性下降。因此,研究水化膨胀作用与力学参数之间的关系是研究泥岩井壁稳定的关键内容之一。基于泥页岩的水化作用机理,通过室内实验分析了水基钻井液中的离子类型及其浓度对水化膨胀应力的影响,并且测量了岩样水化后的力学参数。实验结果表明泥岩水化膨胀应力与离子类型和浓度有关;水化后泥岩的含水量越大,产生的线膨胀应力越大,力学参数越小;线膨胀应力与泥岩水化后的力学参数之间具有较好的指数递减关系。

Experiment Study on Relationship between Swelling Pressure and Mechanical ParametersXU Liqun LIU Houbin MENG Yingfeng

Wellbore instability in mudstone formation often occurs when mudstone contacts with the water based drilling fluid. Therefore, the research on the influence of mudstone hydration on rock strength is one of key contents in the study of the wellbore stability of mudstone formation. This laboratory experiment measured swelling pressure in different ion types and contents. Moreover,axial compressive tests were performed to investigate the impact of water content on compressive strength of mudstone. The results show that the ion types and the content had an influence on the swelling pressure of mudstone. In addition, it is shown that the swelling pressure increased with the water content increasing, however, mechanical parameters decreased with the water content increasing. Also, results show that there was a good exponential decay relationship between the swelling pressure and mechanical parameters.