Neutron well logging using one source and two detectors; the apparent limestone porosity is calculated by computer from the ratio of the count rate of one detector to that of the other.
Related Terms 
COLD CRANKING SIMULATOR
An intermediate shear rate viscometer that predicts the ability of an oil to permit a satisfactory cranking speed to be developed in a cold engine. (CCS)

ACCELERATION
The rate of change of velocity, as a function of time. Expressed in m/s2.

ACCELERATION
The time rate of change of velocity; i.e., the derivative of velocity; with respect to time.

HORIZONTAL EARTH RATE
The rate at which the spin axis of a gyroscope must be tilted about the horizontal axi

FILTRATION (BETA) RATIO
The ratio of the number of particles greater than a given size in the influent fluid to the number of particles greater than the same size in the effluent fluid.

ADIABATIC EFFICIENCY
The ratio of actual work output of a heat engine to the ideal output.

FILTER LIFE TEST
A type of filter capacity test in which a clogging contaminant is added to the influent of a filter, under specified test conditions, to produce a given rise in pressure drop across the filter or until a specified reduction of flow is reached. Filter life may be expressed as test time required to reach terminal conditions at a specified contaminant addition rate.

BETARATIO (ßRATIO)
The ratio of the number of particles greater than a given size in the influent fluid to the number of particles greater than the same size in the effluent fluid, under specified test conditions (see 'MultiPass Test').

BULK MODULUS (OF ELASTICITY)
A ratio of normal stress to a change in volume. A term used in determining the compressibility of a fluid. Data for petroleum products can be found in the International Critical Tables.

LIQUID
Any substance that flows readily or changes in response to the smallest influence. More generally, any substance in which the force required to produce a deformation depends on the rate of deformation rather than on the magnitude of the deformation.
