Studying the effect of carbonatite heterogeneity on hydraulic fracture initiationby using finite element method

Analytic solution mainly used in fracturing initiation research for heterogeneous carbonatite has certain limitation. When fluid percolation exists in actual formation, fluid-solid coupling should be considered. Considering both the heterogeneity of rock mechanics and the coupling effect between fluid and solid deformation, stress field distribution around the borehole was established, and finite element method was used to study the hydraulic fracture initiation in heterogeneous carbonatite. It is shown that heterogeneity of elasticity modulus, poisson ratio and reservoir permeability affects fracturing initiation significantly. Meanwhile, the heterogeneity leads to multi-point fracture initiation near the wellbore. In the formation with weak interlayer, the location of fracture initiation is correlated with interlayer location. The results have a critical influence on the further improvement of optimization design of hydraulic fracturing.