Effects of water saturation on P-wave propagation in fractured coals: An experimental perspective

Jie Liu, Dameng Liu*, Yidong Cai, Quan Gan, Yanbin Yao

*Corresponding author for this work

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

Internal structure of coalbed methane (CBM) reservoirs can be evaluated through ultrasonic measurements. The compressional wave that propagates in a fractured coal reservoir may indicate the internal coal structure and fluid characteristics. The P-wave propagation was proposed to study the relations between petrophysical parameters (including water saturation, fractures, porosity and permeability) of coals and the P-wave velocity (Vu), using a KON-NM-4A ultrasonic velocity meter. In this study, the relations between VPs and water saturations were established: Type I is mainly controlled by capillary of developed seepage pores. The controlling factors on Type II and Type III are internal homogeneity of pores/fractures and developed micro-fractures, respectively. Micro-fractures density linearly correlates with the V-p due to the fracture volume and dispersion of P-wave; and micro-fractures of types C and D have a priority in V-p. For dry coals, no clear relation exists between porosity, permeability and the V-p. However, as for water-saturated coals, the correlation coefficients of porosity, permeability and Vp are slightly improved. The V-p of saturated coals could be predicted with the equation of V-p-saturated = 1.4952V(p)-dry-26.742 m/s. The relation between petrophysical parameters of coals and Vp under various water saturations can be used to evaluate the internal structure in fractured coals. Therefore, these relations have significant implications for coalbed methane (CBM) exploration. (C) 2017 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)94-103
Number of pages10
JournalJournal of Applied Geophysics
Volume144
Early online date8 Jul 2017
DOIs
Publication statusPublished - Sep 2017

Keywords

  • Water saturation
  • P-wave propagation
  • NMR
  • Fractured coals
  • RAY COMPUTED-TOMOGRAPHY
  • PERMEABILITY EVOLUTION
  • MECHANICAL-PROPERTIES
  • SEISMIC ATTENUATION
  • BASIN COALS
  • VELOCITY
  • FLUID
  • SANDSTONE
  • ROCKS
  • IMPACT

Cite this

Effects of water saturation on P-wave propagation in fractured coals : An experimental perspective. / Liu, Jie; Liu, Dameng; Cai, Yidong; Gan, Quan; Yao, Yanbin.

In: Journal of Applied Geophysics, Vol. 144, 09.2017, p. 94-103.

Research output: Contribution to journalArticle

@article{4f22ceb809bd4ebf851a5627f00a93b6,
title = "Effects of water saturation on P-wave propagation in fractured coals: An experimental perspective",
abstract = "Internal structure of coalbed methane (CBM) reservoirs can be evaluated through ultrasonic measurements. The compressional wave that propagates in a fractured coal reservoir may indicate the internal coal structure and fluid characteristics. The P-wave propagation was proposed to study the relations between petrophysical parameters (including water saturation, fractures, porosity and permeability) of coals and the P-wave velocity (Vu), using a KON-NM-4A ultrasonic velocity meter. In this study, the relations between VPs and water saturations were established: Type I is mainly controlled by capillary of developed seepage pores. The controlling factors on Type II and Type III are internal homogeneity of pores/fractures and developed micro-fractures, respectively. Micro-fractures density linearly correlates with the V-p due to the fracture volume and dispersion of P-wave; and micro-fractures of types C and D have a priority in V-p. For dry coals, no clear relation exists between porosity, permeability and the V-p. However, as for water-saturated coals, the correlation coefficients of porosity, permeability and Vp are slightly improved. The V-p of saturated coals could be predicted with the equation of V-p-saturated = 1.4952V(p)-dry-26.742 m/s. The relation between petrophysical parameters of coals and Vp under various water saturations can be used to evaluate the internal structure in fractured coals. Therefore, these relations have significant implications for coalbed methane (CBM) exploration. (C) 2017 Elsevier B.V. All rights reserved.",
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author = "Jie Liu and Dameng Liu and Yidong Cai and Quan Gan and Yanbin Yao",
note = "This research was funded by the National Natural Science Foundation of China (Grant No. 41602170), the Fundamental Research Funds for Central Universities (Grant No. 35832015136) and the Key Project of Coal-based Science and Technology in Shanxi Province-CBM accumulation model and reservoir evaluation in Shanxi province (Grant No. MQ2014-01).",
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T1 - Effects of water saturation on P-wave propagation in fractured coals

T2 - An experimental perspective

AU - Liu, Jie

AU - Liu, Dameng

AU - Cai, Yidong

AU - Gan, Quan

AU - Yao, Yanbin

N1 - This research was funded by the National Natural Science Foundation of China (Grant No. 41602170), the Fundamental Research Funds for Central Universities (Grant No. 35832015136) and the Key Project of Coal-based Science and Technology in Shanxi Province-CBM accumulation model and reservoir evaluation in Shanxi province (Grant No. MQ2014-01).

PY - 2017/9

Y1 - 2017/9

N2 - Internal structure of coalbed methane (CBM) reservoirs can be evaluated through ultrasonic measurements. The compressional wave that propagates in a fractured coal reservoir may indicate the internal coal structure and fluid characteristics. The P-wave propagation was proposed to study the relations between petrophysical parameters (including water saturation, fractures, porosity and permeability) of coals and the P-wave velocity (Vu), using a KON-NM-4A ultrasonic velocity meter. In this study, the relations between VPs and water saturations were established: Type I is mainly controlled by capillary of developed seepage pores. The controlling factors on Type II and Type III are internal homogeneity of pores/fractures and developed micro-fractures, respectively. Micro-fractures density linearly correlates with the V-p due to the fracture volume and dispersion of P-wave; and micro-fractures of types C and D have a priority in V-p. For dry coals, no clear relation exists between porosity, permeability and the V-p. However, as for water-saturated coals, the correlation coefficients of porosity, permeability and Vp are slightly improved. The V-p of saturated coals could be predicted with the equation of V-p-saturated = 1.4952V(p)-dry-26.742 m/s. The relation between petrophysical parameters of coals and Vp under various water saturations can be used to evaluate the internal structure in fractured coals. Therefore, these relations have significant implications for coalbed methane (CBM) exploration. (C) 2017 Elsevier B.V. All rights reserved.

AB - Internal structure of coalbed methane (CBM) reservoirs can be evaluated through ultrasonic measurements. The compressional wave that propagates in a fractured coal reservoir may indicate the internal coal structure and fluid characteristics. The P-wave propagation was proposed to study the relations between petrophysical parameters (including water saturation, fractures, porosity and permeability) of coals and the P-wave velocity (Vu), using a KON-NM-4A ultrasonic velocity meter. In this study, the relations between VPs and water saturations were established: Type I is mainly controlled by capillary of developed seepage pores. The controlling factors on Type II and Type III are internal homogeneity of pores/fractures and developed micro-fractures, respectively. Micro-fractures density linearly correlates with the V-p due to the fracture volume and dispersion of P-wave; and micro-fractures of types C and D have a priority in V-p. For dry coals, no clear relation exists between porosity, permeability and the V-p. However, as for water-saturated coals, the correlation coefficients of porosity, permeability and Vp are slightly improved. The V-p of saturated coals could be predicted with the equation of V-p-saturated = 1.4952V(p)-dry-26.742 m/s. The relation between petrophysical parameters of coals and Vp under various water saturations can be used to evaluate the internal structure in fractured coals. Therefore, these relations have significant implications for coalbed methane (CBM) exploration. (C) 2017 Elsevier B.V. All rights reserved.

KW - Water saturation

KW - P-wave propagation

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KW - Fractured coals

KW - RAY COMPUTED-TOMOGRAPHY

KW - PERMEABILITY EVOLUTION

KW - MECHANICAL-PROPERTIES

KW - SEISMIC ATTENUATION

KW - BASIN COALS

KW - VELOCITY

KW - FLUID

KW - SANDSTONE

KW - ROCKS

KW - IMPACT

U2 - 10.1016/j.jappgeo.2017.07.001

DO - 10.1016/j.jappgeo.2017.07.001

M3 - Article

VL - 144

SP - 94

EP - 103

JO - Journal of Applied Geophysics

JF - Journal of Applied Geophysics

SN - 0926-9851

ER -