The rock breaking mechanism and application effect of pulse type controllable shock wave

Fracturing is an effective means of improving oil recovery in reservoirs, and controllable shock wave is a new type of fracturing technology. In this paper, firstly, combining a large-scale true tri-axial fracturing simulation experimental device with a pulse type controllable shock wave fracturing rock system, pulse type repetitive controllable shock wave induced rock fracturing experiments under tri-axial stress loading conditions is conducted. Then, the complexity of crack propagation and the direction of crack propagation are analyzed. Thirdly, the oilfield application effect of oil well stimulation is analyzed. Results show that: (a) The transverse seam breaks through the boundary in the form of multiple main seams and branch seams. The cracks are intricate and intertwined, with a high degree of complexity. (b) The optimal number of pulse type controllable shock waves for wells of 9NAN242-S264, 9NAN256-240, 9NAN234-S268, 9NAN234-S274, and 9NAN202-S288 are 36, 30, 30, 30, and 36, respectively. (c) Oilfield production operations were completed for 5 oil wells, with an average daily increase of 2.7 t of liquid and 2.6 t of oil per well in the initial stage after the measures were implemented.