Determination of permeability-compaction relationship from interpretation of permeability-stress data for shales from eastern and northern Canada

Katsube, T J; Coyner, Karl B.

doi:10.4095/193867

Cited by 7 publications

(8 citation statements)

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“…Although a detailed discussion of the permeability±stress dependence is not within the scope of this paper, it can be mentioned that the permeability decreases by up to two orders of magnitude upon an increase of effective stress from 7 to 45 MPa. The stepwise permeability reduction could be expressed by two different exponential curves similar to the results reported by Katsube & Coyner (1994) and Katsube & Williamson (1997) for mudrocks from the Beaufort MacKenzie Basin, North-west Territories, Canada. Porosity determined by mercury porosimetry again revealed systematic differences between the two mudrock sample sets.…”

Section: Mineralogy and Geochemistrysupporting

confidence: 75%

Molecular transport of methane, ethane and nitrogen and the influence of diffusion on the chemical and isotopic composition of natural gas accumulations

Schloemer¹,

Krooss²

2004

Geofluids

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Laboratory experiments have been performed to determine diffusion coef®cients of natural gas components (methane, ethane and nitrogen) and isotope fractionation effects under simulated in situ pressure (up to 45 MPa effective stress) and temperature conditions (50±2008C) in water-saturated pelitic and coarse-grained rocks. Effective diffusion coef®-cients of molecular nitrogen (0.39 Â 10 À11 to 21.6 Â 10 À11 m 2 sec À1 at 908C) are higher than those for methane (0.18 Â 10 À11 to 18.2 Â 10 À11 m 2 sec À1 at 908C). Diffusive¯ux rates expressed in mass units are generally higher for N 2 than for CH 4 . Both methane and (to a lesser extent) nitrogen diffusion coef®cients decrease with increasing total organic carbon (TOC) content of the rock samples because of sorption processes on the organic matter. This effect decreases with increasing temperature. Effective diffusion coef®cients increase upon a temperature increase from 50 to 2008C by a factor of four. Effective diffusion coef®cients and steady-state diffusive¯ux decrease with effective stress. Stationary diffusive¯uxes drop by 50±70% for methane and 45±62% for nitrogen while effective diffusion coef®cients are reduced by 38% (CH 4 ) and 32±48% (N 2 ), respectively. Isotope fractionation coef®cients of diffusive transport are higher for methane (À1.56 and À2.77%) than for ethane (À0.84 and À1.62%). Application of the experimental results to geological systems show that diffusive transport has only a low transport ef®ciency. Signi®cant depletion of natural gas reservoirs by molecular diffusion is only expected in cases of very poor caprock qualities (in terms of thickness and/ or porosity) and over extended periods of geological time. Under these circumstances, the chemical and isotopic composition of a gas reservoir will change and maturity estimates based on these parameters may be deceptive. To account for these potential effects, nomograms have been developed to estimate diffusive losses and apply maturity corrections.

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Section: Mineralogy and Geochemistrysupporting

confidence: 75%

Molecular transport of methane, ethane and nitrogen and the influence of diffusion on the chemical and isotopic composition of natural gas accumulations

Schloemer¹,

Krooss²

2004

Geofluids

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“…This characteristic of permeability behaviour was reported by several authors for clay bearing rocks (Katsube & Coyner 1994;Dewhurst et al 1998;Faulkner & Rutter 1998;Kwon et al 2004), demonstrating that pressure cycling recovers depressurization (expansion) damage and returns the permeability-effective pressure behaviour to its state at the depth corresponding to the maximum pressure applied.…”

Section: Sensitivity Of Permeability To Confining Pressurementioning

confidence: 73%

Microstructural controls on the pressure-dependent permeability of Whitby mudstone

Mckernan

Mecklenburgh²,

Rutter³

et al. 2017

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A combination of permeability and ultrasonic velocity measurements allied with image analysis is used to distinguish the primary microstructural controls on effective-pressure dependent permeability. Permeabilities of cylindrical samples of Whitby Mudstone were measured using the oscillating pore pressure method at confining pressures ranging between 30-95 MPa and pore pressures ranging between 1-80 MPa. The permeability-effective pressure relationship is empirically described using a modified effective pressure law in terms of confining pressure, pore pressure and a Klinkenberg effect. Measured permeability ranges between 3×10 -21 m 2 and 2 ×10 -19 m 2 (3 and 200 nd), and decreases by ~1 order of magnitude across the applied effective pressure range. Permeability is shown to be less sensitive to changes in pore pressure than changes in confining pressure, yielding permeability effective pressure coefficients ( ) between 0.42 and 0.97. Based on a pore-conductivity model which considers the measured changes in acoustic wave velocity and pore volume with pressure, the observed loss of permeability with increasing effective pressure is attributed dominantly to the progressive closure of bedding-parallel, crack-like pores associated with grain boundaries.Despite only constituting a fraction of the total porosity, these pores form an interconnected network that significantly enhances permeability at low effective pressures.The pre-publication reference is: Mckernan, R., Mecklenburgh, J., Rutter, E. H. and Taylor Progress in understanding fluid transport properties of mudstones is currently hindered by a scarcity of published experimental data. However, the ongoing expansion of the hydrocarbon industry into low-permeability unconventional resources is driving the demand for research and development in this field. Even when hydraulic fracture treatment is used to enhance production, flow of hydrocarbons into the fractures will be controlled ultimately by the microporous, low permeability matrix. Furthermore, during reservoir production pore-fluid pressure is progressively reduced, which acts to increase the in-situ Terzaghi effective pressure (defined as overburden pressure minus pore pressure), thereby decreasing permeability. The evolution of permeability of the matrix therefore determines the prediction of long-term production, which must take into account the effects of flow regime, multiphase flow, sorption effects, permeability anisotropy and, most importantly, the pressuredependence of permeability.Laboratory measurements of permeability of intact mudstone samples performed under reservoir conditions has yielded values between 10 -22 m 2 and 10 -12 m 2 (0.1 nD and 1 D) for flow both parallel and normal to layering (Morrow et al.

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“…at higher pressures (Katsube & Coyner, 1994) by the transient technique (Brace et al, 1968), using the following equation (Katsube et al, 1991a):…”

Section: Theory and Experimental Programsmentioning

confidence: 99%

“…~np, dnp, q~ ....... and o = nano-pore porosity, nano-pore mode, maximum nano-pore partial porosity and standard deviation (based on log of pore-size, d; . k0 permeability at atmospheric pressure extrapolated from measurements at higher pressures (Katsube & Coyner, 1994). F and % formation factor and apparent tortuosity (Katsube et al, 1991a).…”

Section: B a S I C C H A R A C T E R I S T I C S O F S H A L E Smentioning

confidence: 99%

Effects of diagenesis on shale nano-pore structure and implications for sealing capacity

Katsube

Williamson

1994

Clay miner.

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A B S T R A C T:The effect of diagenesis on shale petrophysical characteristics is being investigated as part of a study on shale sealing capacity because of its significance for modelling hydrocarbon charge histories of sedimentary basins. Results to date indicate that diagenesis (degree of cementation and dissolution) significantly affects porosity and inter-connectivity of the nano-pores (0.3~0 nm), the pores constituting the main pore-throats for tight shales. Diagenesis causes tight shale permeabilities to vary over a range exceeding an order of magnitude (113 21 -6 x 10 2o m 2) and porosities to vary between 1 and 12%. In addition, diagenesis significantly influences shale nano-pore resistance to collapse during compaction and burial, mainly at depth > 2-3 km, affecting hydrocarbon trapping, overpressure and sealing capacities. Dissolution tends to delay the timing of excess pressure pulses, while cementation has a reverse effect. The significance of diagenesis is reduced at shallower depths.

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Determination of permeability-compaction relationship from interpretation of permeability-stress data for shales from eastern and northern Canada

Cited by 7 publications

References 0 publications

Molecular transport of methane, ethane and nitrogen and the influence of diffusion on the chemical and isotopic composition of natural gas accumulations

Molecular transport of methane, ethane and nitrogen and the influence of diffusion on the chemical and isotopic composition of natural gas accumulations

Microstructural controls on the pressure-dependent permeability of Whitby mudstone

Effects of diagenesis on shale nano-pore structure and implications for sealing capacity

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