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| Titel |
Lithological controls on matrix permeability of organic-rich shales: An experimental study |
| VerfasserIn |
Amin Ghanizadeh, Matus Gasparik, Alexandra Amann-Hildenbrand, Bernhard M. Krooss |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250072564
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| Zusammenfassung |
| Despite considerable gas-in-place (GIP) estimations for shale gas plays, these complex
heterogeneous reservoirs require innovative exploration and completion strategies to produce
natural gas economically. Economic gas flow rates in these reservoirs, which commonly have
permeability coefficients down to the nDarcy-range, are still technically difficult to achieve,
partially due to the poor understanding of the fluid transport processes within the fracture and
matrix systems of these lithotypes. This contribution will present results from an ongoing
laboratory study investigating the fluid transport properties in the matrix system of the
organic-rich shales, differing in pore network characteristics (porosity, pore size distribution),
mineralogy (calcite, clay, quartz), TOC content (3-14 %) and maturity (0.6-2.4
%Ro).
Single- and two-phase fluid flow experiments were conducted within the frame of the
GASH project (www.gas-shales.org). Gas (He, Ar, CH4) and water flow properties were
determined at effective stresses ranging between 8 and 37 MPa and temperatures of 25 and
45Ë C. The effects of different controlling factors/parameters on the conductivity were
analysed and will be discussed:
Influence of maturity on intrinsic permeability: Among the sample suite studied,
the lowest permeability coefficients in parallel and perpendicular directions were
measured at intermediate maturity levels (oil-window; 0.85 - 1.05 %Ro).
Poro-perm-relationship: The Klinkenberg-corrected gas
permeability coefficients increased significantly with porosity (4-16 %) ranging
between 4-
10-22 and 9.7-
10-17m2.
Anisotropy of permeability: Permeability coefficients measured parallel to
bedding were more than one order of magnitude higher than those measured
perpendicular to bedding. The permeability anisotropy appeared, furthermore, to
be controlled by the mineral composition.
Influence of permeating fluid on intrinsic permeability: Permeability coefficients
measured with He were consistently up to five times higher than those
measured with Ar and CH4 under similar experimental conditions. A substantial
discrepancy between Klinkenberg-corrected gas permeability coefficients and
water permeability coefficients (0.5-10-
10-21 m2) was observed for both
immature and overmature samples.
Influence of moisture on intrinsic permeability: Klinkenberg-corrected gas (He,
Ar, CH4) permeability coefficients measured on dried samples were about six
times higher than those measured on as-received sample (moisture content:
1.1%). |
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