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A Modified Numerical Model for Production-Induced Stress in Refracturing Gas Well

  • H. X. Xu
  • Z. W. Wang
  • M. Zhang
Conference paper
Part of the Springer Series in Geomechanics and Geoengineering book series (SSGG)

Abstract

Technical key points of deflection refracturing are the selections of the most reasonable refracturing time and parameters, based on the changes of original geostresses. Production-induced stress due to pore pressure change is one of the dominant factors influencing geostress reorientation; however, displacement discontinuity of the fracture surface has hardly been considered in numerical models for production-induced stress both at home and abroad; also the solution procedures of the present models are relatively complicated, and the convergences are relatively poor. In this paper, based on poroelasticity theory and seepage mechanics, a modified fluid–structure interaction model for production-induced stress in refracturing gas well was established and solved by the hybrid method of displacement discontinuity method (DDM) and finite difference method (FDM), and then the distribution characteristics of the production-induced stress with time and space were obtained. Calculations indicate that decreasing range of maximum horizontal principal stress is greater than that of minimum horizontal principal stress due to pore pressure reduction, and this is a major factor leading to stress reorientation. The higher the production time and production pressure drop are and the smaller the original horizontal stress difference is, the easier it will be to form stress reorientation area. Meanwhile, shear stress around the fracture increases due to the fluid–structure interaction during production, which helps increase the complexities of new fractures. The new numerical model for production-induced stress takes discontinuous displacement of the fracture section into consideration. In addition, the calculation method is simple and has satisfactory convergence. The study results have certain significance to improve the success rate of refracturing in oil gas well by providing scientific guidance for well and layer selection and construction time selection.

Keywords

Refracturing gas well Production-induced stress Stress reorientation DDM FDM 

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Copyright information

© Springer Nature Singapore Pte Ltd. 2019

Authors and Affiliations

  1. 1.CCDC Changqing Down Hole Technology CompanyXi’anChina

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