Initiation, propagation, closure and morphology of hydraulic fractures in sandstone cores

Hydraulic fracturing is an important technology for the development of unconventional gas such as tight sand gas. In this paper, a series of fracturing experiments were conducted on hollow cylindrical sandstone specimens with a diameter of 50 mm to investigate the initiation, propagation, and closure of hydraulic fractures. In addition, microscope and X-ray CT scanner were employed to observe the morphology of fractures in the surfaces and the internal structures of fractured specimens. The fracture widths were calculated based on the experimental monitoring of circumference by extensometer and CT scanning results. The results demonstrate the dominant role in width evolution of hydraulic fractures. The results can provide some basic data for the design in hydraulic fracturing of tight oil/gas reservoirs.