Gas saturated coal failure envelope establishment through single core multistage triaxial loading tests

Long Fan, Shimin Liu

Research output: Contribution to conferencePaper

Abstract

Coal properties may behavior in a different way under in situ reservoir conditions from other traditional reservoirs because of the combined effects of effective stress and sorbing-gas induced matrix property changes.Multistage triaxial testing can generate a full failure envelope using a single plug core, especially for the test when there is insufficient number of cores to run the standard triaxial tests. In this paper, a series of multistage triaxial compression testes of gas saturated coal cores were conducted based on ISRM standard procedures to determine the mechanical properties of reservoir coal formations as a function of confining stress and gas pressure.Coal strength deterioration due to phase-dependent gas adsorption was investigated.It demonstrated that coal strength with adsorbing gas injection had a positive correlation with confining stress; coalspecimen showed plasticization under a higher confining stress condition; anthracite coal has a strong adsorption effect on CO2 and the free gas phase CO2 adsorption can cause a dramatic peak strength deterioration; coal strength deterioration was exacerbated with respect to gas pressure. However, as the gas was in subcritical phase, gas density increasing induced hardening effect may be dominant; supercritical CO2 led to a strong softening on coal skeleton and resulted in a plasticization of coal under a quite small confining stress condition.

Original languageEnglish (US)
StatePublished - Jan 1 2019
Event53rd U.S. Rock Mechanics/Geomechanics Symposium - Brooklyn, United States
Duration: Jun 23 2019Jun 26 2019

Conference

Conference53rd U.S. Rock Mechanics/Geomechanics Symposium
CountryUnited States
CityBrooklyn
Period6/23/196/26/19

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All Science Journal Classification (ASJC) codes

  • Geochemistry and Petrology
  • Geophysics

Cite this

Fan, L., & Liu, S. (2019). Gas saturated coal failure envelope establishment through single core multistage triaxial loading tests. Paper presented at 53rd U.S. Rock Mechanics/Geomechanics Symposium, Brooklyn, United States.