STOMP

Mechanical Properties Card Options (EOR)

Compressibility Options

Geologic media in STOMP-W is considered to be slightly compressible. Compressibility is considered to be an intrinsic property of a rock/soil type. Compressibility can be specified via three options:

Bulk Compressibility

Bulk compressibility is the change in the bulk rock volume with respect to change in pressure at constant temperature:

Bulk and pore compressibility can be related as:

Symbols

bulk compressibility, 1/Pa
pore compressibility, 1/Pa
total porosity
 bulk volume, m3
 aqueous liquid pressure, Pa
 temperature, K
Pore Compressibility

Pore compressibility is the change in pore volume with respect to change in pressure at constant temperature:

Bulk and pore compressibility can be related as:

Symbols

pore compressibility, 1/Pa
bulk compressibility, 1/Pa
total porosity
  pore volume, m3
 aqueous liquid pressure, Pa
  temperature, K
Specific Storage

Specific storage is the amount of water that a portion of an aquifer releases from storage, per unit mass or volume of aquifer, per unit change in hydraulic head, while remaining fully saturated.  Specific storage can be expressed in terms of water density, porosity, water compressibility, and bulk rock compressibility as:

and

Symbols

specific storage, 1/m
density of water, kg/m3
bulk compressibility, 1/Pa
 water compressibility, 1/Pa
 total porosity
 volume of water, m3
  aqueous liquid pressure, Pa
 temperature, K
 acceleration of gravity, m/s2

Specific storage is converted to bulk compressibility via the specified diffusive porosity and a standard compressibility of water. As with particle density, default values of specific storativity will be computed for null entries of both the specific storativity and its associated units.  Default specific storativity is computed from the diffusive porosity and a default value of 1.x10–7 1/Pa for the compressibility.

Sub-Options

Either or both of the following options can be used with any of the Compressibility Options.

IJK, JKI or KIJ Indexing

If IJK Indexing, JKI Indexing, or KIJ Indexing is specified as the Rock/Soil Name in the Rock/Soil Zonation Card, then this must also be specified as the Rock/Soil Name in the Mechanical Properties Card.

IJK Indexing

If the IJK Indexing option is specified in the Rock/Soil Zonation Card, then any or all of the mechanical properties parameters can be specified either as a single value that will be applied to each node in the domain, or in an external file with the values for every grid-cell ordered according to the IJK indexing scheme. Units shown in the input line will be applied to all parameters in the external file. 

JKI Indexing

If the JKI Indexing option is specified in the Rock/Soil Zonation Card, then any or all of the mechanical properties parameters can be specified either as a single value that will be applied to each node in the domain, or in an external file with the values for every grid-cell ordered according to the JKI indexing scheme. Units shown in the input line will be applied to all parameters in the external file. 

KIJ Indexing

If the KIJ Indexing option is specified in the Rock/Soil Zonation Card, then any or all of the mechanical properties parameters can be specified either as a single value that will be applied to each node in the domain, or in an external file with the values for every grid-cell ordered according to the KIJ indexing scheme. Units shown in the input line will be applied to all parameters in the external file. 

Equivalent Continuum Model

If the keyword '(ec),' appears in the rock/soil name specified in the Rock/Soil Zonation Card, additional inputs for fracture porosity, fracture spacing, fracture aperture, and fracture compressibility are required.  

Tortuosity Functions

Tortuosity functions are required for simulations that involve solute transport or diffusion of components through phases (e.g., water vapor diffusing through the gas phase or dissolved oil diffusing through the aqueous phase).  Tortuosities can be computed either as:

Constants

When choosing the constant option, specific input values for the tortuosity factor may be specified.

Millington and Quirk Model

Tortuosity can be specified using functions of the phase saturation and diffusive porosity according to the formulation of Millington and Quirk (1959):

Symbols

tortuosity
diffusive porosity
actual aqueous liquid saturation
Millington and Quirk Gas with Constant Aqueous

In this option the gas phase tortuosity is based on the formulation of Millington and Quirk (1959) and the aqueous tortuosity is specified by a constant tortuosity factor.

Marshall

Tortuosity can be specified using functions of the phase saturation and diffusive porosity according to the formulation of Marshall (1959):

Symbols

tortuosity
diffusive porosity
actual aqueous liquid saturation

References: 

Dandekar, A. Y., 2006. Petroleum Reservoir Rock and Fluid Properties. CRC Taylor & Francis, ISBN-13: 978-0-8493-3043-8.

Marshall, TJ. 1959. The diffusion of gases through porous media. J. Soil Sci., 10, 79–82.

Millington, RJ. and JP Quirk. 1959. Permeability of porous media. Nature 183:387-388.

STOMP User Guide Home

Modules