Air-Water Relative Permeability Studies of Pittsburgh and Pocahontas Coals

1974 ◽  
Vol 14 (06) ◽  
pp. 556-562 ◽  
Author(s):  
A.A. Reznik ◽  
M.K. Dabbous ◽  
P.F. Fulton ◽  
J.J. Taber
Keyword(s):  
Steady State ◽  
Water Saturation ◽  
Gas Permeability ◽  
Dynamic Properties ◽  
Flow Behavior ◽  
Phase Flow ◽  
Relative Permeabilities ◽  
Two Phase ◽  
Overburden Pressure ◽  
Experimental Apparatus

Abstract Air and water relative permeabilities have been measured for numerous samplesof Pittsburgh and Pocahontas coals. Tests were performed under steady<stateconditions for both drainage and imbibition cycles. Results indicate that theflow of gas is greatly reduced during the latter process, whereas duringdrainage it is largely undiminished over a wide water-saturation range. It isalso shown that imbibition saturation distributions obtained from liquid-waterimbibition as opposed to water-vapor adsorption produce gas permeability curvesof radically different character. The effective permeabilities to both gas andwater were significantly reduced with the application of overburden pressuresin the range of 0 to 1,000 psig, but the general shapes of the relativepermeability curves remained the same. Introduction Past studies of the spatial and dynamic properties of coal have been limited tosingle-phase flow. The present energy shortage has created renewed interest inthe in-situ combustion of coal to low-Btu gas. The infusion of water into coalseams appears to be effective in abating methane emissions from coal mines.Both these processes require a detailed understanding of two-phase (liquid andgas) flow behavior in coal beds. The purpose of this paper is to extend the work of Dabbous et al. to includethe two-phase flow data on Pittsburgh and Pocahontas coals for air-watersystems. The present data consist of air and water permeabilities measured asfunctions of saturation, saturation history, and overburden pressure. The experimental apparatus and cutting and mounting techniques employed in thisstudy are identical with those described in the first paper. We note, however, that the structural integrity of the samples was maintained during tests thatin some cases extended intermittently over a 6-month period. Measurement of Relative Permeabilities Almost all the effective and relative permeabilities to air and water weremeasured under approximately steady-state conditions by the stationary-phasemethod in which one of the fluids is immobilized within the sample by capillaryforces. However, in a series of runs conducted on a sample of Pittsburgh coal, gas and water relative permeabilities were determined by the Penn State method- that is, the fluids were flowed simultaneously until steady-state equilibriumwas established.

scholarly journals Modeling and Simulation of Flow and Formation Damage of Asphalt-Paved Roads

2013 ◽  
Vol 2013 ◽  
pp. 1-5
Author(s):  
M. H. Alawi ◽  
M. M. El-Qadi ◽  
M. A. El-Ameen
Keyword(s):  
Mathematical Modeling ◽  
Suspended Solids ◽  
Fine Particles ◽  
Water Saturation ◽  
Formation Damage ◽  
Phase Flow ◽  
Relative Permeabilities ◽  
Two Phase ◽  
Porous Asphalt ◽  
Porosity And Permeability

Porous asphalt is a standard asphalt built on aggregate storage bed which allows water to drain through it and reduces stormwater runoff. However, porosity of the porous asphalt and the storage bed may be effectively reduced due to trapping suspended solids from the water or from the asphalt damage. In this paper, we present mathematical modeling and numerical simulation of flow and damage of porous asphalt-paved roads. A mathematical model to describe the fine-particles transport carried by a two-phase flow in a porous medium is presented. The buoyancy, capillarity, and mixed relative permeabilities correlations to fit with the mixed-wet system are considered. Throughout this investigation, we monitor the changing of the fluids properties such as water saturation and solid properties such as porosity and permeability due to trapping the fine-particles.

scholarly journals Towards Relative Permeability Measurements in Tight Gas Formations

2020 ◽  
Vol 146 ◽  
pp. 05001
Author(s):  
Denis Dzhafarov ◽  
Benjamin Nicot
Keyword(s):  
Steady State ◽  
Relative Permeability ◽  
Water Saturation ◽  
Gas Permeability ◽  
Tight Gas ◽  
Two Phase ◽  
Pressure Step ◽  
Injection Ratio ◽  
Insight Into ◽  
Good Agreement

Relative permeability is a concept used to convey the reduction in flow capability due to the presence of multiple fluids. Relative permeability governs the multiphase flow, therefore it has a significant importance in understanding the reservoir behavior. These parameters are routinely measured on conventional rocks, however their measurement becomes quite challenging for low permeability rocks such as tight gas formations. This study demonstrates a methodology for relative permeability measurements on tight gas samples. The gas permeability has been measured by the Step Decay method and two different techniques have been used to vary the saturations: steady state flooding and vapor desorption. Series of steady-state gas/water simultaneous injection have been performed on a tight gas sample. After stabilization at each injection ratio, NMR T2, NMR Saturation profile and low pressure Step Decay gas permeability have been measured. In parallel, progressive desaturation by vapor desorption technique has been performed on twin plugs. After stabilization at each relative humidity level the NMR T2 and Step Decay gas permeability have been measured in order to compare and validate the two approaches. The techniques were used to gain insight into the tight gas two phase relative permeability of extremely low petrophysical properties (K<100 nD, phi < 5 pu) of tight gas samples of Pyrophyllite outcrop. The two methods show quite good agreement. Both methods demonstrate significant permeability degradation at water saturation higher than irreducible. NMR T2 measurements for both methods indicates bimodal T2-distributions, and desaturation first occurs on low T2 signal (small pores). Comparison of humidity drying and steady-state desaturation technique has shown a 12-18 su difference between critical water saturation (Swc) measured in gas/water steady-state injection and irreducible saturation (Swirr) measured by vapor desorption.

scholarly journals Steady-State Two-Phase Flow in Porous Media: Laboratory Validation of Flow-Dependent Relative Permeability Scaling

2020 ◽  
Vol 146 ◽  
pp. 03002
Author(s):  
Marios S. Valavanides ◽  
Matthieu Mascle ◽  
Souhail Youssef ◽  
Olga Vizika
Keyword(s):  
Porous Media ◽  
Steady State ◽  
Relative Permeability ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Flow In Porous Media ◽  
Phase Flow ◽  
Relative Permeabilities ◽  
Two Phase ◽  
Local Flow

The phenomenology of steady-state two-phase flow in porous media is recorded in SCAL relative permeability diagrams. Conventionally, relative permeabilities are considered to be functions of saturation. Yet, this has been put into challenge by theoretical, numerical and laboratory studies that have revealed a significant dependency on the flow rates. These studies suggest that relative permeability models should include the functional dependence on flow intensities. Just recently a general form of dependence has been inferred, based on extensive simulations with the DeProF model for steady-state two-phase flows in pore networks. The simulations revealed a systematic dependence of the relative permeabilities on the local flow rate intensities that can be described analytically by a universal scaling functional form of the actual independent variables of the process, namely, the capillary number, Ca, and the flow rate ratio, r. In this work, we present the preliminary results of a systematic laboratory study using a high throughput core-flood experimentation setup, whereby SCAL measurements have been taken on a sandstone core across different flow conditions -spanning 6 orders of magnitude on Ca and r. The scope is to provide a preliminary proof-of-concept, to assess the applicability of the model and validate its specificity. The proposed scaling opens new possibilities in improving SCAL protocols and other important applications, e.g. field scale simulators.

Simulation of Two-Phase Flow in Reservoir Rocks Using a Lattice Boltzmann Method

SPE Journal ◽  
2010 ◽  
Vol 15 (04) ◽  
pp. 917-927 ◽  
Author(s):  
Thomas Ramstad ◽  
Pål-Eric Øren ◽  
Stig Bakke
Keyword(s):  
Steady State ◽  
Capillary Pressure ◽  
Relative Permeability ◽  
Lattice Boltzmann ◽  
Two Phase Flow ◽  
Constitutive Relations ◽  
Phase Flow ◽  
Relative Permeabilities ◽  
Two Phase ◽  
Rock Microstructure

Summary We present results from simulations of two-phase flow directly on digitized rock-microstructure images of porous media using a lattice Boltzmann (LB) method. The implemented method is performed on a D3Q19 lattice with fluid/fluid and fluid/solid interaction rules to handle interfacial tension and wetting properties. We demonstrate that the model accurately reproduces capillary and wetting effects in pores with a noncircular shape. The model is applied to study viscous coupling effects for two-phase concurrent annular flow in circular tubes. Simulated relative permeabilities for this case agree with analytical predictions and show that the nonwetting-phase relative permeability might greatly exceed unity when the wetting phase is less viscous than the nonwetting phase. Two-phase LB simulations are performed on microstructure images derived from X-ray microtomography and process-based reconstructions of Bentheimer sandstone. By imposing a flow regulator to control the capillary number of the flow, the LB model can closely mimic typical experimental setups, such as centrifuge capillary pressure and unsteady- and steady-state relative permeability measurements. Computed drainage capillary pressure curves are found to be in excellent agreement with experimental data. Simulated steady-state relative permeabilities at typical capillary numbers in the vicinity of 10−5 are in fair agreement with measured data. The simulations accurately reproduce the wetting-phase relative permeability but tend to underpredict the nonwetting-phase relative permeability at high wetting-phase saturations. We explain this by pointing to percolation threshold effects of the samples. For higher capillary numbers, we correctly observe increased relative permeability for the nonwetting phase caused by mobilization and flow of trapped fluid. It is concluded that the LB model is a powerful and promising tool for deriving physically meaningful constitutive relations directly from rock-microstructure images.

Optic Imaging of Two-Phase-Flow Behavior in 1D Nanoscale Channels

SPE Journal ◽  
2014 ◽  
Vol 19 (05) ◽  
pp. 793-802 ◽  
Author(s):  
Qihua Wu ◽  
Baojun Bai ◽  
Yinfa Ma ◽  
Jeong Tae Ok ◽  
Keith B. Neeves ◽  
...  
Keyword(s):  
Fluid Flow ◽  
Shale Gas ◽  
Two Phase Flow ◽  
Water Saturation ◽  
Flow Behavior ◽  
Gas Production ◽  
Production Optimization ◽  
Phase Flow ◽  
Two Phase ◽  
Small Pore

Summary Gas in tight sand and shale exists in underground reservoirs with microdarcy (µd) or even nanodarcy (nd) permeability ranges; these reservoirs are characterized by small pore throats and crack-like interconnections between pores. The size of the pore throats in shale may differ from the size of the saturating-fluid molecules by only slightly more than one order of magnitude. The physics of fluid flow in these rocks, with measured permeability in the nanodarcy range, is poorly understood. Knowing the fluid-flow behavior in the nanorange channels is of major importance for stimulation design, gas-production optimization, and calculations of the relative permeability of gas in tight shale-gas systems. In this work, a laboratory-on-chip approach for direct visualization of the fluid-flow behavior in nanochannels was developed with an advanced epi-fluorescence microscopy method combined with a nanofluidic chip. Displacements of two-phase flow in 100-nm-depth slit-like channels were reported. Specifically, the two-phase gas-slip effect was investigated. Under experimental conditions, the gas-slippage factor increased as the water saturation increased. The two-phase flow mechanism in 1D nanoscale slit-like channels was proposed and proved by the flow-pattern images. The results are crucial for permeability measurement and understanding fluid-flow behavior for unconventional shale-gas systems with nanoscale pores.

Sign in / Sign up

Export Citation Format

Share Document