In
petroleum engineering, TEM (true effective mobility), also called TEM-function developed by
Abouzar Mirzaei-Paiaman, is a criterion to characterize dynamic two-phase flow characteristics of rocks (or dynamic rock quality).
TEM is a function of
relative permeability
In multiphase flow in porous media, the relative permeability of a phase is a dimensionless measure of the effective permeability of that phase. It is the ratio of the effective permeability of that phase to the absolute permeability. It can be ...
,
porosity
Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measur ...
, absolute
permeability and fluid
viscosity
The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water.
Viscosity quantifies the inte ...
, and can be determined for each fluid phase separately. TEM-function has been derived from
Darcy's law
Darcy's law is an equation that describes the flow of a fluid through a porous medium. The law was formulated by Henry Darcy based on results of experiments on the flow of water through beds of sand, forming the basis of hydrogeology, a branch of ...
for multiphase flow.
:
in which
is the absolute permeability,
is the relative permeability, φ is the porosity, and μ is the fluid viscosity.
Rocks with better fluid dynamics (i.e., experiencing a lower pressure drop in conducting a fluid phase) have higher TEM versus saturation curves. Rocks with lower TEM versus saturation curves resemble low quality systems.
TEM-function in analyzing relative permeability data is analogous with
Leverett J-function
In petroleum engineering, the Leverett ''J''-function is a dimensionless function of water saturation describing the capillary pressure,
:J(S_w) = \frac
where S_w is the water saturation measured as a fraction, p_c is the capillary pressure ( ...
in analyzing
capillary pressure data. Furthermore, TEM-function in two-phase flow systems is an extension of RQI (rock quality index) for single-phase systems.
Also, TEM-function can be used for averaging relative permeability curves (for each fluid phase separately, i.e., water, oil, gas, ).
:
See also
*
Lak wettability index
*
USBM wettability index
References
Petroleum engineering
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