Abstract
This paper compares the evolution of permeability with effective stress in propped fractures in shale for native CH 4 compared with that for sorbing CO 2 , slightly sorbing N 2 and non-sorbing He. We examine the response for laboratory experiments on artificial propped fractures in Green River Shale to explore mechanisms of proppant embedment and fracture diagenesis. Split cylindrical specimens sandwich a proppant bead-pack at a constant confining stress of 20 MPa and with varied pore pressure. Permeability and sorption characteristics are measured with the pulse transient method. To explore the effect of swelling and embedment on fracture surface geometry, we measure the evolution of conductivity characteristics for different proppant geometries (single layer vs. multilayer), gas saturation and specimen variation in order to simulate both production and enhanced gas recovery. The resulting morphology of embedment is measured by white light interferometry and characterized via surface roughness parameter of mean, maximum and root-mean-square amplitudes. For both strongly (CO 2 , CH 4 ) and slightly adsorptive gases (N 2 ), the permeability first decreases with an increase in gas pressure due to swelling before effective stress effects dominate above the Langmuir pressure threshold. CO 2 with its highest adsorption affinity produces the lowest permeability among these three gas permeants. Monolayer propped specimens show maximum swelling and lowered k/k 0 ratio and increased embedment recorded in the surface roughness relative to the multilayered specimens. Permeabilities measured for both injection and depletion cycles generally overlap and are repeatable with little hysteresis. This suggests the dominant role of reversible swelling over irreversible embedment. Gas permeant composition and related swelling have an important effect on the permeability evolution of shales.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1473-1485 |
| Number of pages | 13 |
| Journal | Rock Mechanics and Rock Engineering |
| Volume | 50 |
| Issue number | 6 |
| DOIs | |
| State | Published - Jun 1 2017 |
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All Science Journal Classification (ASJC) codes
- Civil and Structural Engineering
- Geotechnical Engineering and Engineering Geology
- Geology
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Permeability Evolution of Propped Artificial Fractures in Green River Shale. / Li, Xiang; Feng, Zijun; Han, Gang; Elsworth, Derek; Marone, Chris J.; Saffer, Demian; Cheon, Dae Sung.
In: Rock Mechanics and Rock Engineering, Vol. 50, No. 6, 01.06.2017, p. 1473-1485.Research output: Contribution to journal › Article
TY - JOUR
T1 - Permeability Evolution of Propped Artificial Fractures in Green River Shale
AU - Li, Xiang
AU - Feng, Zijun
AU - Han, Gang
AU - Elsworth, Derek
AU - Marone, Chris J.
AU - Saffer, Demian
AU - Cheon, Dae Sung
PY - 2017/6/1
Y1 - 2017/6/1
N2 - This paper compares the evolution of permeability with effective stress in propped fractures in shale for native CH 4 compared with that for sorbing CO 2 , slightly sorbing N 2 and non-sorbing He. We examine the response for laboratory experiments on artificial propped fractures in Green River Shale to explore mechanisms of proppant embedment and fracture diagenesis. Split cylindrical specimens sandwich a proppant bead-pack at a constant confining stress of 20 MPa and with varied pore pressure. Permeability and sorption characteristics are measured with the pulse transient method. To explore the effect of swelling and embedment on fracture surface geometry, we measure the evolution of conductivity characteristics for different proppant geometries (single layer vs. multilayer), gas saturation and specimen variation in order to simulate both production and enhanced gas recovery. The resulting morphology of embedment is measured by white light interferometry and characterized via surface roughness parameter of mean, maximum and root-mean-square amplitudes. For both strongly (CO 2 , CH 4 ) and slightly adsorptive gases (N 2 ), the permeability first decreases with an increase in gas pressure due to swelling before effective stress effects dominate above the Langmuir pressure threshold. CO 2 with its highest adsorption affinity produces the lowest permeability among these three gas permeants. Monolayer propped specimens show maximum swelling and lowered k/k 0 ratio and increased embedment recorded in the surface roughness relative to the multilayered specimens. Permeabilities measured for both injection and depletion cycles generally overlap and are repeatable with little hysteresis. This suggests the dominant role of reversible swelling over irreversible embedment. Gas permeant composition and related swelling have an important effect on the permeability evolution of shales.
AB - This paper compares the evolution of permeability with effective stress in propped fractures in shale for native CH 4 compared with that for sorbing CO 2 , slightly sorbing N 2 and non-sorbing He. We examine the response for laboratory experiments on artificial propped fractures in Green River Shale to explore mechanisms of proppant embedment and fracture diagenesis. Split cylindrical specimens sandwich a proppant bead-pack at a constant confining stress of 20 MPa and with varied pore pressure. Permeability and sorption characteristics are measured with the pulse transient method. To explore the effect of swelling and embedment on fracture surface geometry, we measure the evolution of conductivity characteristics for different proppant geometries (single layer vs. multilayer), gas saturation and specimen variation in order to simulate both production and enhanced gas recovery. The resulting morphology of embedment is measured by white light interferometry and characterized via surface roughness parameter of mean, maximum and root-mean-square amplitudes. For both strongly (CO 2 , CH 4 ) and slightly adsorptive gases (N 2 ), the permeability first decreases with an increase in gas pressure due to swelling before effective stress effects dominate above the Langmuir pressure threshold. CO 2 with its highest adsorption affinity produces the lowest permeability among these three gas permeants. Monolayer propped specimens show maximum swelling and lowered k/k 0 ratio and increased embedment recorded in the surface roughness relative to the multilayered specimens. Permeabilities measured for both injection and depletion cycles generally overlap and are repeatable with little hysteresis. This suggests the dominant role of reversible swelling over irreversible embedment. Gas permeant composition and related swelling have an important effect on the permeability evolution of shales.
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U2 - 10.1007/s00603-017-1186-2
DO - 10.1007/s00603-017-1186-2
M3 - Article
AN - SCOPUS:85013387672
VL - 50
SP - 1473
EP - 1485
JO - Rock Mechanics and Rock Engineering
JF - Rock Mechanics and Rock Engineering
SN - 0723-2632
IS - 6
ER -