NUMERICAL SIMULATION OF HYDRAULIC FRACTURE PROPAGATION IN NATURALLY FRACTURE FORMATIONS USING COHESIVE ELEMENTS

An integrated cohesive model is presented to analyze hydraulic fracturing jobs in the presence of pre-existing natural fractures. Differences of fracture properties along existing fractures may affect the hydraulic fracture propagation and results in a reduction of final geometry. Activation of natural fractures during fracturing treatment improves the effectiveness of the stimulation tremendously. Cohesive zone model (CZM) approach is used to model both hydraulic and natural fractures using the two-dimensional finite element model. Semicircular bending test (SCBT) was used to determine cohesive parameters that were used as a benchmark to simulate cases when rock properties are stronger than natural fracture and vice-versa. Numerical simulation was carried out to represent the hydraulic fractures' growth in a plane strain reservoir. We found the cases when propagation of the hydraulic fracture will be arrested or will be continued by the presence of a natural fracture based on fracture properties of the rock, magnitude and direction of principal rock stresses, and the angle between fractures.