Preliminary laboratory study on initiation and propagation of hydraulic fractures in granite using X-ray computed tomography

Hydraulic fracturing tests were performed on small cylindrical granite samples with diameter of 30 mm, applying two different injection schemes of continuous and cyclic injection for comparison. The initiation and propagation of hydraulic fractures with increasing number of cycles was investigated using X-ray Computed Tomography (CT). Both of intergranular and intragranular fractures were observed. Moreover, we pointed out two methods that can help improving quality of CT images of granite samples obtained from scanning under external pressures. One is using the engineering plastic cell instead of steel cell to weaken the metal artifact, and another is applying KI solution instead of tap water to enhance fractures inside the sample.