Analysis of the Causes of High Fracturing Pressure in the Kuqa Piedmont Reservoir Based on Stress-Strain Curves

ABSTRACT: The reservoir in front of Kuqa Mountain has the typical characteristics of ultra-high temperature and high-pressure. The fracture pressure is often high during the fracturing construction process, and even the formation cannot be fractured. The GCTS-1500 high-temperature and high-pressure rock mechanics rheometer was used to carry out the triaxial compression experiment under high confining pressure, analyze the differences of mechanical parameters between different wells, and establish a quantitative evaluation model of brittle plasticity based on the rock deformation curve under high stress conditions, to clarify the differences in rock strength and brittle plastic characteristics between refractory wells and normal fracturing wells, and explain the causes of high fracture pressure in refractory wells. Rock strength and fracture energy of Bozi 19 well are the highest, and the reservoir rock strength reaches 425.91MPa, which makes it difficult to rupture during fracturing. The reservoir rock strength has strong anisotropic characteristics, and the overall coring angle shows the vertical direction of > 90°>45°>0°. The elastic anisotropy of rock is strong, the elastic modulus of rock increases nonlinearly with the increase of coring angle. This experiment is of great significance for understanding the causes of high fracture pressure in ultra-deep fracturing.