Experimental investigation of Daqing Oilfield mudstone’s creep characteristic under different water contents

In order to analyze mechanism of casing damage, the uniaxial compression experiment and creep experiment of interbedded mudstone samples from Sanan development area of Daqing Oilfield under different water contents were carried out. The changes of the mudstone’s mechanical parameters and creep characteristics with the increment of water saturation were studied. The results indicate that the rock strength and elastic modulus decrease rapidly with the increment of water content, at the same time, the creep strain and creep strain rate of steady state increase with the increment of water content, and also the steady state creep strain rate is enhanced with the increment of deviatoric stress. Through the creep characteristic curves, a non-linear creep constitutive equation of mudstone considering the change of water contents is established, which will be used in future numerical analysis.