Failure Patterns and Mechanisms of Hydraulic Fracture Propagation Behavior in the Presence of Naturally Cemented Fractures

Abstract

In this study, we use the extended finite element method (XFEM) with a consideration of junction enrichment functions to investigate the mechanics of hydraulic fractures related to naturally cemented fractures. In the proposed numerical model, the lubrication equation is adopted to describe the fluid flow within fractures. The fluid-solid coupling systems of the hydraulic fracturing problem are solved using the Newton-Raphson method. The energy release rate criterion is used to determine the cross/arrest behavior between a hydraulic fracture (HF) and a cemented natural fracture (NF). The failure patterns and mechanisms of crack propagation at the intersection of natural fractures are discussed. Simulation results show that after crossing an NF, the failure mode along the cemented NF path may change from the tensile regime to the shear or mixed-mode regime. When an advancing HF kinks back toward the matrix, the failure mode may gradually switch back to the tensile-dominated regime. Key factors, including the length of the upper/lower portion of the cemented NF, horizontal stress anisotropy, and the intersection angle of the crack propagation are investigated in detail. An uncemented or partially cemented NF will form a more complex fracture network than a cemented NF. This study provides insight into the formation mechanism of fracture networks in formations that contain cemented NF.

Complex Fracture Closure Pressure Analysis During Shut-in: A Numerical Study

“…Our investigation aims at the formation with fully cemented natural fractures. Our previous investigation show that the reservoir with an uncemented or partially cemented natural fracture have stronger formatiom capcity of complex fracture than a cemented natural fracture (Wang et al, 2018a;Wang et al, 2021a). Thus, the pressure decline response during hydraulic fracturing of cemented natural fracture is different from that of uncemented or partially cemented natural fractures.…”

“…Based on the signal processing approach, Eltaleb et al (2021) proposed a novel methodology for DFIT analysis in geothermal reservoirs, which is independent of rock mechnical properties and fracture geometry. Wang et al (2021b) anaylzed the characteristic of pressure decline in fractured horizontal wells, and build up a new model which can quantitatively estimate closure stress and average pore pressure. This model can also infer the uniformity of proppant distribution in the hydraulic fractures.…”

Numerical Investigation of Fracture Morphology Characteristics in Heterogeneous Reservoirs

“…Hydraulic fracture growth depends on the shear slip of natural fractures or Processes 2022, 10, 2604 2 of 18 bedding planes with different cement strengths, which is documented by both numerical results and tri-axial hydraulic fracturing experiments [25,26]. A study demonstrates that after intersecting hydraulic fractures, failure modes within cemented natural fractures may change from tensile regime to mixed-mode or shear regime in heterogeneous reservoirs [27]. Wan et al [28] found that the interaction between large-size natural fractures and hydraulic fractures facilitates the formation of complex fracture meshes through laboratory experiments.…”

Phase Field Modeling of Multiple Fracture Growth in Natural Fractured Reservoirs

“…[17] considered the effect of different natural fracture angels and different wellbore spacing on the expansion path of hydraulic fractures. [18] used the extended finite element method (XFEM) to investigate the damage patterns and fracture propagation mechanisms at the intersection of hydraulic fracture and natural fracture. [19] used the finite discrete element method (FDEM) to investigate the basic laws of shear and tensile damage of natural fractures under the disturbing stresses of hydraulic fractures.…”