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128423 - Numerical Study of Fracture Network Evolution.pdf (6.08 MB)

Numerical study of fracture network evolution during nitrogen fracturing processes in shale reservoirs

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posted on 2023-05-19, 21:25 authored by Zhang, XX, Wang, J, Gao, F, Xiaolin WangXiaolin Wang
This paper develops a numerical model to study fracture network evolution during the nitrogen fracturing process in shale reservoirs. This model considers the differences of incompressible and compressible fluids, shear and tensile failure modes, shale heterogeneity, and the strength and permeability of both shale matrix and bedding planes through the coupling of mechanical-seepage-damage during fracturing fluid injection. The results show that nitrogen fracturing has a lower breakdown pressure and larger seepage zone than hydraulic fracturing under the same injection pressure. Tensile failure was identified as the major reason for the initiation and propagation of fractures. Ignoring the effect of bedding planes, the fracture initiation pressure, breakdown pressure, and fracturing effectiveness reached their maxima when the stress ratio is 1. Under the same strength ratio, the propagation path of the fractures was controlled by the stronger effect that was casused by the bedding angle and stress ratio. With increasing the strength ratio, the fracture number and shearing of the bedding plane increased significantly and the failure pattern changed from tensile-only mode to tensile-shear mode. These analyses indicated that the fracture network of bedding shale was typically induced by the combined impacts of stress ratio, bedding angle and strength ratio.

History

Publication title

Energies

Volume

11

Issue

10

Article number

2503

Number

2503

Pagination

1-22

ISSN

1996-1073

Department/School

School of Engineering

Publisher

MDPI AG

Place of publication

Switzerland

Rights statement

Copyright 2018 the authors. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

Repository Status

  • Open

Socio-economic Objectives

Oil and gas extraction

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