页岩孔隙结构及页岩气开发特征研究-英文

Fracture‒Matrix Interaction
Field observation (preferential flow in a fracture network) of dye distribution in unsaturated fractured tuff at Yucca Mt.
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2006
2004
2000 2008
http://www.eia.gov/pub/oil_gas/natural_gas/analysis_publications/maps/maps.htm
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http://www .eia.gov/tod ayinenergy/ detail.cfm?i d=2170 Updated June 1, 2011
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height
Log mass imbibed
h φa (h ) = φp χ
β ν
1 Slope = = 0.5 2
Pore structure
Barnett Shale (7,219 ft)
pathways
Porosity: 5.5% k: nanodarcys (10-21 m2) Median pore dia.: 5 nm
• Gas deliverability from nanopores to well bore 5
Ewing and Horton (2002)
∂θ ∂ ∂θ = D ( θ ) ∂t ∂x ∂ x
High t 0.5 constant constant Low t 0.263 t -0.48 t -1.83
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• Affected the same way by pore connectivity:
elliptical to completely rounded
Where is the porosity?
angular
rectangular
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CH4 size: 0.375 nm
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http://www.transcanada.com/customerexpress/docs/presentations_general/2009_ North_American_Shale_Gas_Overview_NECA.pdf
(Spontaneous) Imbibition Test
• Rock sample epoxycoated along length → 1D flow • Imbibition rate monitored continuously over time
Balance
• Sample size (cm range) and shape • Different initial water contents • Tracer solution
Pore Structure and Hydrocarbon Recovery in Fractured Shales
(Max) Qinhong Hu 胡钦红 maxhu@uta.edu Department of Earth and Environmental Sciences University of Texas, Arlington
Pore Geometry and Topology
Total Porosity Isolated Porosity Connected Porosity
Edge Porosity
Infinite Cluster
Backbone
Dead Ends
Pore structure: shape, volume, size, sizedistribution, connectivity, a nd surface area 6
Sample dimension
1.33 cm L×1.76 cm W ×1.43 cm H (Vertical) 1.76 cm L×1.72 cm W ×1.32 cm H (Horizontal) 1.38 cm L×1.71 cm W ×1.72 cm H (Vertical) 1.73 cm L×1.73 cm W ×1.21 cm H (Horizontal) 1.35 cm L×1.79 cm W ×1.81 cm H (Vertical) 1.24 cm L×1.78 cm W ×1.32 cm H (Horizontal) 1.24 cm L×1.74 cm W ×1.67 cm H (Vertical) 1.74 cm L×1.72 cm W × 1.26 cm H (Horizontal) 1.37 cm L×1.74 cm W × 1.95 cm H (Vertical) 1.69 cm L×1.71 cm W ×1.36 cm H (Horizontal)
nanopore
0.375 nm
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Fluid Flow and Mass Transport in Stimulated Reservoir Volume
~3×106 m3 for one frac stage (Curtis et al., 2012) 12
http://www.transcanada.com/customerexpress/docs/presentations_general/ 2009_North_American_Shale_Gas_Overview_NECA.pdf
Percolation Theory
The mathematics of how macroscopic properties result from local (microscopic) connections
p is the local connection probability
percolation threshold 0.5 < pc < 0.66 (for 2D square lattice) p = 0.5
“Ant in a labyrinth”
p = 0.66
Solute in a pore system
↔
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Multiple Approaches to Studying Pore Structure
• • • • • • • • • • • • Imbibition with samples of different shapes Edge-accessible porosity Liquid and gas diffusion Mercury injection porosimetry N2 adsorption/desorption isotherms Vapor absorption Nuclear Magnetic Resonance Cryoporometry SEM imaging after Wood’s metal impregnation Microtomography (high-resolution, synchrotron) Focused Ion Beam/SEM imaging Small-Angle Neutron Scattering (SANS) Pore-scale network modeling 17
• • •
Slope = 0.5 at high p Slope = 0.26 at p=pc At intermediate p values, at some time or distance to the wetting front,
the slope transitions from 0.26 to 0.50
Rock milling in 1998
My work on fracture transport starts with this rock
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Intraparticle organic nanopores
Ar-ionbeam milling and fieldemissiongun SEM: resolve pores as small as 5 nm Loucks et al. (2009)
-3.0 -1.5 -0.5
Time (min) in log scale
0.5
1.5
2.5
3.5
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Imbibition Results for Barnett Shale Samples Depth 7,109 ft (2,167 m) 7,136 ft (2,175 m) 7,169 ft (2,185 m) 7,199 ft (2,194 m) 7,219 ft (2,200 m)
Pore-Scale Network: Simulation Results (Ewing of ISU)
• p is pore connectivity probability; pc ≈ 0.2488 is the percolation threshold for cubic lattice
Height/width
Imbibition slope
0.93 0.76 1.12 0.70 1.16 0.87 1.12 0.67 1.25 0.80
0.214 ±0.059 (N=3) 0.291 ±0.027 (N=3) 0.269 ±0.0045 (N=3) 0.216 ±0.040 (N=3) 0.273 ±0.050 (N=3) 0.357 ±0.006 (N=3) 0.284 ±0.062 (N=3) 0.282 ±0.047 (N=3) 0.306 ±0.019 (N=3) 0.264 ±0.046 (N=3) 20
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Low gas recovery factor 15-30% for Barnett Shale (King, 2012)
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Pore Structure and Low Hydrocarbon Production
RPSEA project: “Integrated • Amount of gas experimental and in place modeling approaches • Free vs. to studying the adsorbed gas fracture-matrix interaction in gas • Tortuous recovery from Barnett transport shale”
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Pore Connectivity and Diffusion • Same mathematics for diffusion and imbibition:
∂c ∂ ∂c = Ds (θ ) ∂t ∂x ∂x
Pore connectivity: Time-dependence: Distance to front Diffusion coefficient Distance-dependence: Diffusion coefficient
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Low Pore-Connectivity of Shale Samples
30 sec 5 min 2 hr 20 hr
Cumulative imbibition (mm) in log scale
0.0
-1.0
-2.0
Barnett Shale 2,166.8 m (7,109 ft) Rectangular prism (1.33 cm long × 1.76 cm wide × 1.43 cm tall)
13ቤተ መጻሕፍቲ ባይዱ
中海油以151亿美元收购加拿大Nexen公司, 并承担该公司约43亿美元债务
~1 m/yr movement (advection vs. diffusion ?)
LaFollette, R. 2010. Key Considerations for Hydraulic Fracturing of Gas Shales. Manager, Shale Gas Technology, BJ Services Company, September 9, 2010. www.pttc.org/aapg/lafollette.pdf