固井水泥石三轴力学试验的试样制备方法

固井水泥石力学性能直接关系到水泥环的长期密封效果。获取固井水泥石的力学性能参数主要通过三轴力学试验进行,有效制备试样对固井水泥石三轴力学试验研究乃至水泥环完整性分析至关重要。基于固井水泥石三轴力学试验试样的特殊性,设计探索了正方体水泥石养护成形后取心的正方体取心制样以及借助于模具一次养护成形制样等2种试样制备方法;研制了用于模具养护制样方法的?25.4 mm×50.8 mm小试样和?50.8 mm×101.6 mm大试样2套圆柱形水泥石养护模具;通过散点分布、均方根误差分析、标准差分析等对比研究了56组不同制样方法获取试样的力学试验数据,结果表明,小试样模具制样养护方法在数据可靠性、制样效率及成本等方面均优于其他方法,推荐作为固井水泥石三轴力学试验试样制备方法。

Sample preparation methods for triaxial mechanical test of cementing set cement

The mechanical property of cementing set cement has a direct influence on the long-term sealing effect of cement sheath. The mechanical property parameters of cementing set cement are measured mainly by means of triaxial mechanical test, and effective sample preparation is crucial to triaxial mechanical test study of cementing set cement and the integrity analysis of cement sheath. Considering the peculiarity of the samples for the triaxial mechanical test of cementing set cement, two sample preparation methods were designed and explored. One is prepared from the coring cube after the curing and shaping of cubic set cement, and the other is prepared through primary curing and shaping in a mould. Then, two sets of cylindrical set cement curing moulds used for mould curing based sample preparation method were developed, i.e., small sample ?25.4 mm×50.8 mm and large sample ?50.8 mm×101.6 mm. Finally, 56 sets of mechanical test data of the samples prepared using different methods were comparatively analyzed by virtue of scatter distribution, root-mean-square error (RMSE) analysis and standard deviation analysis. It is indicated that small sample mould based sample preparation and curing method is superior to the other methods in terms of data reliability, sample preparation efficiency and cost, so it is recommended to act as the sample preparation method for the triaxial mechanical test of cementing set cement.