# MATERIAL_PROPERTY¶

This section specifies material properties to be associated with the entire reservoir domain or with a region of it. See example below:

MATERIAL_PROPERTY formation
ID 1
CHARACTERISTIC_CURVES ch1
TORTUOSITY 1.d0
SOIL_COMPRESSIBILITY 4.35d-10 ! 1/Pa
SOIL_REFERENCE_PRESSURE 1.0D5
ROCK_DENSITY 2.350d3
SPECIFIC_HEAT 1.0d3
THERMAL_CONDUCTIVITY_DRY 1.541d0
THERMAL_CONDUCTIVITY_WET 1.541d0
/


The options supported within the MATERIAL_PROPERTY blocks are:

## ID¶

Goes under the MATERIAL_PROPERTY card.

Takes only one integer parameter, which defines the material id by which the material property object may be identified/linked. Most commonly, only one material is defined and associated with the entire reservoir domain, in this case this id must be assign to 1.

For PFLOTRAN advanced users, material ids can be assigned on a cell-by-cell basis to define material regions. Note that ID= 0 is reserved for inactive grid cells and cannot be used in this block. This material id must be entered or the code returns an error.

## CHARACTERISTIC_CURVES¶

Goes under the MATERIAL_PROPERTY card.

Takes only one argument, which is the name of the characteristic curves block to be associated with material. This defines a the set of saturation curves, and must be defined in the same input deck, directly or via an external file. Note that if SATNUM is found in GRDECL, CHARACTERISTIC_CURVES is not required. In this case, the characteristic curves are assigned on a cell-by-cell basis, where the SATNUM cell indexes refers to the order of the characteristic curves, as entered in the input deck.

## TORTUOSITY¶

Goes under the MATERIAL_PROPERTY card.

Takes only one argument, the tortuosity coefficient that corrects the molecular diffusion of the components in the fluid phases. Currently molecular diffusion of the components is accounted only in the GAS_WATER mode. If not entered the tortuosity defaults to 1, i.e. no correction of the molecular diffusion coefficients.

## SOIL_COMPRESSIBILITY¶

Goes under the MATERIAL_PROPERTY card.

Defines the compressibility coefficient of pore space to be entered in [1/Pa], see compressibility models in the theory guide. As is conventional in reservoir simulation, this coefficient reflects the expansivity of the pore space, rather than the compressibility of the rock grains.

Note the rock compressibility coefficients are specified in 1/Pa, not the 1/Bar units which may be assumed in some other simulator metric unit systems.

## SOIL_COMPRESSIBILITY_FUNCTION¶

Goes under the MATERIAL_PROPERTY card.

Used instead of “Rock Compressibility function”.

Take one argument that specifies the type of pore space compressibility function for which the options available are [LEIJNSE, BRAGFLO, QUADRATIC]. It defaults to the exponential LEIJNSE form. However, QUADRATIC may be used to match the compressibility form commonly used in reservoir simulation. See compressibility models in the theory guide.

## SOIL_REFERENCE_PRESSURE¶

Goes under the MATERIAL_PROPERTY card.

Used instead of “Rock reference pressure”.

Defines the reference pressure for the computation of rock compressibility effects, which can be assigned a constant value to be entered in [Pa], for example:

SOIL_REFERENCE_PRESSURE 1.0D5


The reference pressure will be computed internally as the maximum pressure resulting from the initialisation when selecting the INITIAL_PRESSURE option, e.g.

SOIL_REFERENCE_PRESSURE  INITIAL_PRESSURE


## ROCK_DENSITY¶

Goes under the MATERIAL_PROPERTY card.

Takes one argument, which defines the rock density of the material to be entered in [kg/m3].

## SPECIFIC_HEAT¶

Goes under the MATERIAL_PROPERTY card.

Takes one argument, which defines specific heat capacity of material to be entered in [J/(kg-K)]

## THERMAL_CONDUCTIVITY_DRY¶

Goes under the MATERIAL_PROPERTY card.

Takes one argument, which is the dry thermal conductivity of material to be entered in [W/(K-m)]. This is the thermal conductivity of the rock considered fully saturated with gas.

## THERMAL_CONDUCTIVITY_WET¶

Goes under the MATERIAL_PROPERTY card.

Takes one argument, the wet thermal conductivity of material to be entered in [W/(K-m)]. This is the thermal conductivity of the rock considered fully saturated with liquid. Note that liquid implies water and oil together. In general a grid block may contain both gas and liquid. The thermal conductivity of the rock partially saturated with liquid and gas is computed as follows:

$\lambda = \lambda_{\mbox{dry}} + S_{\mbox{liq}}^{1/2}\left( \lambda_{\mbox{wet}}- \lambda_{\mbox{dry}} \right)$

where the liquid saturation is equal to the sum of the oil and water saturation ($$S_{\mbox{liq}} =S_w + S_o$$ ).