Model of fracture initiation of the refracturing deep wells

The fracture initiation of fractured ERW differ from those of the vertical and the conventional directional wells, the initiation mode is not only relative to the well trajectory (deviation and azimuth angle) but also the in-situ stress azimuth.

The mathematical model of the fracture initiation pressure is established,and according to the solution of the model,the conclusions can be drawn that if wellbore azimuth angle is different,the effects of vertical principal stress and minimum horizont.

Mechanism of hydraulically created fracture breakdown and propagation based on fractal method;

Mode Ⅰ crack propagation criterion of concrete and numerical simulation on complete process of cracking;

The main work of this paper are as follows:1、By utilizing I-II mixed mode Crack Propagation Criterion of concrete,2D arbitrarily crack propagation comes true by using APDL(ANSYS parameter design language).