Control system and apparatus for delivery of a non-aqueous fracturing fluid

Abstract

A system is described that provides for proppant to be blended into a liquefied gas fluid stream with an eductor to produce a proppant slurry which is effectively controlled by the use of a control valve system and associated PLC controller. This system ensures allowing for operation of the system at various static pressures and keeps the proppant completely fluidized throughout the fracing operation.

What is claimed is: 
     
         1 . A system for controlling proppant concentration in a fracturing fluid that is utilized in stimulation of an underground, comprising:
 providing a proppant reservoir having a proppant or proppant slurry therein and disposed in a position to supply the proppant or proppant slurry to an eductor;   providing an eductor to receive a motive fluid flow of liquefied gas at pressure between 150 and 450 psig, wherein the eductor is disposed below the proppant reservoir and forms a fracturing fluid containing proppant at the outlet of the eductor upon receiving the proppant or proppant slurry from the proppant reservoir; and   providing a proppant control valve disposed between the proppant reservoir and the eductor, wherein the pad pressure in the proppant reservoir is varied from about −30 to 40 psi to attain a concentration range from about 0.1 to 10 lbs/gal of proppant in the fracturing fluid.   
     
     
         2 . The system of  claim 1 , further comprising a concentration meter downstream of the eductor, wherein the concentration meter can be selected from among a Corolis meter, a nuclear densitometer, and a magnetic flow meter. 
     
     
         3 . The system of  claim 1 , further comprising a computer in communication with the concentration meter, wherein the computer receives a reading from the concentration meter, compares it to a set value, and varying the opening of the proppant control valve to attain the desired concentration. 
     
     
         4 . The system of  claim 1 , further comprising a programmable logic controler for varying the pad pressure and the opening of the proppant control valve in the system. 
     
     
         5 . The system of  claim 1 , wherein the system does not include an augur to meter the proppant or propprant slurry into the motive flow of liquefied gas. 
     
     
         6 . The system of  claim 1 , further comprising a bypass line providing a potion of the motive fluid flow of liquefied gas that is combined with the fracturing fluid downstream of the eductor. 
     
     
         7 . The system of  claim 1 , further comprising a liquid addition line in communication with the lower part of the proppant reservoir, wherein the liquid added promotes a liquid-solid suspension of proppant in the slurry. 
     
     
         8 . The system of  claim 1 , further comprising a liquid addition line in communication with the upper part of the proppant reservoir, wherein a liquid cap is provided above the proppant medium therein. 
     
     
         9 . The system of  claim 1 , further comprising a vapor addition line in communication with the upper part of the proppant reservoir, wherein the vapor is utilized to vary the pad pressure in the proppant reservoir. 
     
     
         10 . The system of  claim 1 , further comprising a pressure relief valve control valve disposed on the upper part of the proppant reservoir to relieve excess pressure stored in the head space of the proppant reservoir. 
     
     
         11 . The system of  claim 1 , wherein the proppant reservoir is disposed in a vertically oriented position.