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,
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 measure ...
, 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 analyzing
capillary pressure In fluid statics, capillary pressure () is the pressure between two immiscible fluids in a thin tube (see capillary action), resulting from the interactions of forces between the fluids and solid walls of the tube. Capillary pressure can serve as bo ...
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 In petroleum engineering, Lak wettability index, developed by Abouzar Mirzaei-Paiaman is a quantitative indicator to measure wettability of rocks from relative permeability data. This index is based on a combination of Craig's first rule. and mod ...
*
USBM wettability index
References
Petroleum engineering
{{fluiddynamics-stub