The Influence of an Interlayer on Dual Hydraulic Fractures Propagation

Abstract

Multi-cluster hydraulic fracturing of long-range horizontal wells is an approach for enhancing the productivity of low-permeability shale reservoirs. In this study, RFPA-Petrol (rock failure process analysis on petroleum problems) is applied for modeling hydraulic fracture propagation in multilayered formations. RFPA-Petrol based on coupled hydraulic-mechanical-damage (HMD) modeling was first tested by modeling a laboratory scale experiment on a physical (cement) model with a single completion. The modeling demonstrated the capability of RFPA-Petrol for simulating hydraulic fracture propagation. Then, we used RFPA-Petrol to investigate how the difference in material properties between oil-bearing layers and interlayers and the fracturing fluid properties influence the propagation of dual fractures in multilayered laboratory-scale models. In this case, the models with geological discontinuities in the vertical direction are strongly heterogeneous and RFPA-Petrol simulations successfully modeled the fracture configurations.

TOUGH-RFPA: Coupled thermal-hydraulic-mechanical Rock Failure Process Analysis with application to deep geothermal wells

“…Its mechanical behavior is modeled by an elastic damage constitutive law, and the residual strain/deformation upon unloading is not considered [56][57][58].…”

“…• Mechanical damage of an element can be initiated based on the Mohr-Coulomb failure criterion combined with a maximum tensile stress criterion [56][57][58].…”

“…• The fluid flow in the porous and fractured media is governed by Darcy's law. The hydraulic behavior responds to changes in the stress field by considering effective stress and by porosity and permeability variation [41,[56][57][58].…”

“…The permeability of an element varies as a function of the porosity during elastic deformation, increases according to a strain-dependent law when the element is damaged and obeys the assumption of pipe laminar flow after failure [56][57][58].…”

“…When an element exceeds its strength, we can consider the degradation of Young's modulus to be physically manifested as the development of fractures [66]. Thus, we assume that a damaged element can conceptually be represented hydraulically as a unit of rock containing three orthogonal fractures with smooth parallel sides [56,58].…”