Study on dynamic and static elastic moduli of shale oil by different loading methods

Abstract

Experiments on the dynamic and static elastic parameters under distinct loading conditions help clarify the effects of loading rate and strain amplitude on dynamic and static elastic moduli, and gain further insight into the moduli. Significant scientific guidance are provided for fracturing transformation of oil shale reservoirs. AutoLab 1500, servo-controlled triaxial equipment with ultrasonic transducers, is used in an elastic parameter test on shale oil samples. The test concludes that the loading rate moves the dynamic elastic modulus little, with a maximum change rate of 0.8%, while it significantly affects the static elastic modulus by 31.7% at most. In the loading or unloading phase, the larger the initial differential stress (or strain), the higher the dynamic Young's modulus. The static elastic modulus, on the other hand, presents a significant negative correlation with the stress amplitude. To be specific, the smaller the strain amplitude, the higher the measured modulus; the larger the strain amplitude, the smaller the modulus. Given the loading rate, the smaller the differential stress, the smaller the difference between the dynamic and static elastic moduli. This study can provide a reference base for fracturing construction in oil shale.

Keywords

• Shale oil
• Stress cycles
• Dynamic and static elastic moduli
• Rock mechanics
• Elastic parameters