Study on Effect of Rock Interface on Hydraulic Fracture in W9 Offshore Gas Field

Abstract

Abstract In-situ principal stresses in ZH formation of W9 offshore gas field are measured by Kaiser effect method, and the horizontal minimum stress profile is interpreted by logging information. Static Young’s modulus and Poisson’s ratio of rock are measured by tri-axial loading experimental system, and cohesion and internal friction angle of rock are calculated by empirical formula based on logging data. Failure mode discrimination equation of hydraulic fracture at the rock interface is established applying stress analysis of hydraulic fracture tips at rock interface combined with tensile failure criterion and shear failure criterion. In-situ stresses and strength parameters in ZH formation are used to calculate and analyze the control effect of interface on hydraulic fracture propagation. The calculation results show it is necessary to control fracture height growth in ZH formation of W9 offshore gas field, which is of great significance on guiding the optimization of fracturing parameters in this field.