基于H-J-C模型的水化页岩破碎有限元分析

针对页岩地层钻井过程中钻井液对页岩水化作用的问题,提出了基于H-J-C模型的页岩含水饱和度与钻头破岩效率对应关系研究方法,开展了页岩含水饱和度对页岩力学特性影响规律的室内实验。通过室内实验研究发现:页岩含水饱和度对页岩强度、弹性/剪切模量、泊松比等宏观力学参数影响较大,得到不同饱和度工况下水化页岩力学参数值。借助LS-DYNA有限元软件,基于页岩破坏的H-J-C模型,利用室内实验得到的水化页岩的力学参数,模拟了钻头破碎页岩的动态过程。对水化页岩的应力变化、破碎形态、破碎效率进行了研究。结果表明:随着页岩含水饱和度增加,页岩强度降低,钻头破碎岩石的效率增加,当页岩含水饱和度从0.05增加到0.4时,钻头破碎岩石的效率增加了3.3倍。

Hydratable shale breaking finite element analysis based on H-J-C model

Aim at the problem of drilling fluid for the shale hydration during drilling shale, the research methods of corresponding relationship between shale water saturation and rock breaking efficiency based on the HJC model was proposed, and laboratory experiments was carried out, which studied the influence of water saturation on the shale mechanical properties. Through laboratory research, we found that shale water saturation had a big impact on the macroscopic mechanical properties of shale strength, elastic/shear modulus, Poisson"s ratio, and shale hydration mechanical parameters were obtained at the same time. With LS-DYNA finite element software and HJC models for shale damage, using the mechanical parameters obtained by laboratory experiments, the dynamic process of the drill crushing shale was simulated. Stress, broken form, crushing efficiency of shale hydration was studied, the results showed that: with the increase of shale water saturation, shale strength decreased, but the efficiency of drill crushing rock d; when shale water saturation increased from 0.05 to 0.4, the drill rock crushing efficiency increased by 3.3-fold.