Abstract: Apparatus and method are provided for loading a cell for testing crush-resistance of a proppant or other granular material. The apparatus includes a rod valve and one or two screens selected to allow proppant to pluviate into the cell. Stress may be applied to the cell and the amount of proppant crushed by the stress may be measured. Measurements may be repeated to produce mean and variance values. Screen sizes may be varied to select sizes to minimize variance of measurements.

Abstract: A cell assembly for determining the conductivity and permability of proppants in simulated subterranean formations comprising a plurality of vertically stacked cell units interconnected such that upon application of a compressive force the compressive force is transmitted equally throughout each of the cell units. Each of the cell units comprises a cell body member having a passageway extending therethrough; a lower piston connected to the cell body member such that one end thereof extends a selected distance into a lower portion of the passageway and an opposed second end extends outwardly therefrom for reciprocal movement within a cell body member of a second cell unit placed therebelow; and an upper piston member positionable in an upper portion of the passageway for reciprocal movement therein in response to force directed thereon, the upper piston member functioning as the lower piston member for a cell unit disposed thereabove.

Abstract: Integratable circuit arrangement for delaying pulse-shaped signals. A differential amplifier circuit is composed of a first current source connected to a zero potential, of an emitter-coupled transistor pair and of two resistors. The two collectors of the transistor pair are respectively connected to the zero potential via a further current source and are connected to one another via a capacitor. A further transistor introduced into both collector lines of the transistor pair delays pulse-shaped signals that are applied at the bases of the transistor pair and the further transistor in a defined allocation to one another, delaying the signals as a function of the current flowing in the coupled emitters of the transistor pair and as a function of the voltage appearing across the capacitor.

Abstract: A cell assembly for determining the conductivity and permeability of proppants in simulated subterranean formations comprising a plurality of vertically stacked cell units interconnected such that upon application of a compressive force the compressive force is transmitted equally throughout each of the cell units. Each of the cell units comprises a cell body member having a passageway extending therethrough; a lower piston connected to the cell body member such that one end thereof extends a selected distance into a lower portion of the passageway and an opposed second end extends outwardly therefrom for reciprocal movement within a cell body member of a second cell unit placed therebelow; and an upper piston member positionable in an upper portion of the passageway for reciprocal movement therein in response to force directed thereon, the upper piston member functioning as the lower piston member for a cell unit disposed thereabove.

Abstract: A cell assembly for determining the conductivity and permeability of proppants in simulated subterranean formations comprising a plurality of vertically stacked cell units interconnected such that upon application of a compressive force the compressive force is transmitted equally throughout each of the cell units. Each of the cell units comprises a cell body member having a passageway extending therethrough; a lower piston connected to the cell body member such that one end thereof extends a selected distance into a lower portion of the passageway and an opposed second end extends outwardly therefrom for reciprocal movement within a cell body member of a second cell unit placed therebelow; and an upper piston member positionable in an upper portion of the passageway for reciprocal movement therein in response to force directed thereon, the upper piston member functioning as the lower piston member for a cell unit disposed thereabove.