Assessment of Hydraulic Fracturing in Tightreservoirforco2 Geological Storage
Fracture initiation and propagation could occur if the CO 2 pressure exceeds the closure stress by CO 2 injection in
tight reservoir. Propagation of hydraulic fracturing in the vertical direction is unfavorable as it imposes leakage risk, while
propagation in the horizontal direction could be favorableas it will make the increase of the CO 2 injectivity and storage
capacity. The existence of fractures could also be beneficial as it will mitigate a sharp pressure increase by CO 2
injection.This paper presents the assessment of CO 2 storage capacity considering geomechanics through hydraulic fracturing
in tight reservoir.Hydraulic fracture propagation simulations were performed to evaluate the effects of the brittleness on
fracture propagation behavior by CO 2 injection. The used model implements a multiple planar fracture approach with mixed
mode, the fracture crossing criterion used to predict whether the hydraulic fracture will cross the natural fracture in the
model. This criterion and the amount of storable CO 2 volumes were compared for fracture modes of opening and mixed in
various brittleness index. As a result, Young’s modulus is the more sensitive factor than Poisson’s ratio on fracture crossing
angles. With larger brittleness index, the CO 2 storage capacity was calculated to be larger because fracture crossing occurred
easily.It can be helpful for safety assessment of CO 2 storage projects.
Index Terms: CO 2 storage capacity, Hydraulic fracturing, Brittleness index, Sliding mode, Tight reservoir.