Issue 47

Z.-Y. Han et alii, Frattura ed Integrità Strutturale, 47 (2019) 74-81; DOI: 10.3221/IGF-ESIS.47.07 79 a) SL-1 b) SL-2 c) SL-3 Figure 7 : Rock sample fracturing curve. Figure 8: Curve of fracture pressure with stress difference. Influence of fracturing fluid displacement In comparisons of the experimental results of sample SL-3, SL-6, and SL-7, the following conclusion can be drawn that the fracture pressure increases as the displacement of the fracturing fluid increases, by changing the pumping displacement of the fracturing fluid while keeping other reference factors constant, as shown in Fig. 9. Similarly, there is no regularity in the initiation time with the change of displacement. From the point of view of fracture-forming ability, it is easier to form main fractures with larger displacement on the premise of well-developed shale bedding, as shown in Fig. 10. However, the effect of crack propagation in the formation of secondary seams under large displacement is not good. 13,44 10,5 8,6 0 2 4 6 8 10 12 14 16 0 2 4 6 8 10 Fracture pressure/MPa Stress difference/MPa