Proppant control in an lpg frac system

Abstract

An apparatus for supplying proppant is disclosed, comprising a vessel and a level monitor. The vessel has an interior containing a mixture of proppant and liquid, an inlet for supplying proppant to the interior, and an outlet for supplying the mixture of proppant and liquid from the interior of the vessel. The level monitor is associated with the vessel for monitoring at least a level of liquid and has a discriminator for discriminating between the level of liquid and a level of proppant in the mixture of proppant and liquid. A method of supplying proppant is also disclosed. A vessel is provided at least partially filled with a mixture of proppant and liquid and having a level of liquid and a level of proppant. The level of liquid in the mixture of proppant and liquid is monitored. The mixture of proppant and liquid is supplied from the vessel through an outlet in the vessel.

1 . An apparatus for supplying proppant comprising:
 a vessel having an interior containing a mixture of proppant and liquid, an inlet for supplying proppant to the interior, and an outlet for supplying the mixture of proppant and liquid from the interior of the vessel; and   a level monitor associated with the vessel for monitoring at least a level of liquid and having a discriminator for discriminating between the level of liquid and a level of proppant in the mixture of proppant and liquid.   
   
   
       2 . The apparatus of  claim 1  in which the discriminator comprises a sheath having an upper end, a lower end, at least an opening at or near the lower end for allowing liquid in the interior to flow into the sheath and at least restricting the flow of proppant into the sheath, and an equalization vent. 
   
   
       3 . The apparatus of  claim 2  in which the sheath is straight along a sheath length. 
   
   
       4 . The apparatus of  claim 2  in which the sheath spans an upper end of the interior to a lower end of the interior. 
   
   
       5 . The apparatus of  claim 2  in which the level monitor is configured to use time domain reflectometry to determine the level of liquid within the sheath. 
   
   
       6 . The apparatus of  claim 2  in which the opening comprises at least one slot. 
   
   
       7 . The apparatus of  claim 2  in which the opening comprises a proppant screen. 
   
   
       8 . The apparatus of  claim 1  in which the level monitor is located at least partially outside the interior of the vessel. 
   
   
       9 . The apparatus of  claim 1  in which the vessel further comprises a liquid inlet for supplying liquid to the interior of the vessel. 
   
   
       10 . The apparatus of  claim 1  in which the vessel comprises a positive-pressure vessel. 
   
   
       11 . The apparatus of  claim 10  in which the liquid comprises liquefied petroleum gas. 
   
   
       12 . The apparatus of  claim 1  in which the outlet is connected to supply proppant into a pressurized stream of fluid. 
   
   
       13 . The apparatus of  claim 1  in which the mixture of proppant and liquid is a mixture of proppant wetted with liquid. 
   
   
       14 . The apparatus of  claim 1  in which the level monitor is configured to monitor both the level of liquid and the level of proppant. 
   
   
       15 . A method of supplying proppant comprising:
 providing a vessel at least partially filled with a mixture of proppant and liquid and having a level of liquid and a level of proppant;   monitoring the level of liquid in the mixture of proppant and liquid; and   supplying the mixture of proppant and liquid from the vessel through an outlet in the vessel.   
   
   
       16 . The method of  claim 15  in which monitoring further comprises monitoring the level of liquid within a sheath in the vessel, the sheath having at least an opening at or near a lower end of the sheath for allowing liquid to flow into the sheath and at least restricting the flow of proppant into the sheath, and an equalization vent. 
   
   
       17 . The method of  claim 16  in which the sheath spans from an upper end of the vessel to a lower end of the vessel. 
   
   
       18 . The method of  claim 16  in which the opening comprises a proppant screen. 
   
   
       19 . The method of  claim 16  in which monitoring further comprising monitoring using time domain reflectometry. 
   
   
       20 . The method of  claim 15  in which the vessel is pressurized. 
   
   
       21 . The method of  claim 20  in which the liquid comprises liquefied petroleum gas. 
   
   
       22 . The method of  claim 20  in which the mixture of proppant and liquid is supplied from the vessel to a pressurized stream of fluid. 
   
   
       23 . The method of  claim 15  in which liquid is supplied into the vessel from an inlet in the vessel. 
   
   
       24 . The method of  claim 23  further comprising controlling the supply of liquid into the vessel based on the level of liquid in the vessel. 
   
   
       25 . The method of  claim 15  in which the mixture of proppant and liquid is a mixture of proppant wetted with liquid. 
   
   
       26 . The method of  claim 15  further comprising monitoring a level of proppant in the vessel. 
   
   
       27 . An apparatus for supplying proppant comprising:
 a pressure vessel having an interior containing a mixture of proppant and liquid, an inlet for supplying proppant to the interior, and an outlet at or near a base of the interior for supplying the mixture of proppant and liquid from the interior of the pressure vessel; and   a level monitor associated with the pressure vessel for monitoring at least a level of liquid of the mixture of proppant and liquid.   
   
   
       28 . The apparatus of  claim 27  in which the liquid comprises liquefied gas.