Viscosity differential fracturing for enhanced application of amendments to ground and groundwater

Abstract

Viscosity Differential Fracturing uses pneumatic and hydraulic fracturing techniques and a viscosity differential to achieve greater networking, higher amendment loading rates and more controlled propagation. Pneumatic fracturing is applied first in order to create a dense network of small fractures. This is followed by a hydraulic component using a viscosity adjusted fluid. This material can be injected into these fractures at a significant flow rate and extend/expand these fractures while filling them with the fluid. The significant advantage of VDF versus traditional hydraulic fracturing is that the density of fractures created by the initial gas process leads to an overall greater density of fractures emplaced within the subsurface coupled with the ability to emplace a greater mass of material (e.g. proppants, sand, reactants).

1 . A system for viscosity differential fracturing of ground comprising:
 a pneumatic fracturing component; a hydraulic injection component, including a mixture of water and a suspending or thickening agent at a concentration between about 1 and about 50 mg/L, and a non-reactive or reactive material at a concentration between about 0.1 and 30 pounds per gallon; and downhole injection tooling.   
     
     
         2 . The system of  claim 1 , wherein the pneumatic fracturing component includes a high-pressure/high-flow module, an injection control manifold module, a digital flowmeter module, a pressure monitoring module, and a transducer/data-logger monitoring module. 
     
     
         3 . The system of  claim 1 , wherein the hydraulic injection component includes a mobile mixing and injection plant further comprising a re-circulation batch tank with a load-cell weighing module, an automated dry material hopper/feed screw module, a progressive cavity pump, a digital flowmeter module, a pressure monitoring module, and a transducer/data-logger monitoring module. 
     
     
         4 . The system of  claim 1 , wherein the suspending or thickening agent comprises guar. 
     
     
         5 . The system of  claim 1 , wherein the non-reactive or reactive material comprises an about 1% to about 80% solids mixture. 
     
     
         6 . The system of  claim 1 , wherein the downhole injection tooling includes an injection assembly further comprising a plurality of pneumatic packers and a pipe including a plurality of slots. 
     
     
         7 . The system of  claim 1 , wherein the downhole injection tooling includes an injection assembly further comprising a nozzle including a plurality of openings. 
     
     
         8 . The system of  claim 1 , wherein the downhole injection tooling includes an injection assembly further comprising a spring-loaded nozzle. 
     
     
         9 . The system of  claim 1 , wherein the system creates a dense fracture network with a radius of influence of at least about 12 feet and with at least about 2 orders of magnitude increase in subsurface flow rates. 
     
     
         10 . A system for viscosity differential fracturing of ground comprising:
 a pneumatic fracturing component, including a high-pressure/high-flow module, an injection control manifold module, a digital flowmeter module, a pressure monitoring module, and a transducer/data-logger monitoring module; a hydraulic injection component, including a mobile mixing and injection plant further comprising a re-circulation batch tank with a load-cell weighing module, an automated dry material hopper/feed screw module, a progressive cavity pump, a digital flowmeter module, a pressure monitoring module, and a transducer/data-logger monitoring module; and   downhole injection tooling, including an injection assembly further comprising a plurality of pneumatic packers and a pipe including a plurality of slots, wherein the system creates a dense fracture network with a radius of influence of about 12 to 15 feet and with about 2 to about 3 order of magnitude increase in subsurface flow rates.   
     
     
         11 . A system for viscosity differential fracturing of ground comprising:
 a pneumatic fracturing component, including a high-pressure/high-flow module, an injection control manifold module, a digital flowmeter module, a pressure monitoring module, and a transducer/data-logger monitoring module; a hydraulic injection component, including a mobile mixing and injection plant further comprising a re-circulation batch tank with a load-cell weighing module, an automated dry material hopper/feed screw module, a progressive cavity pump, a digital flowmeter module, a pressure monitoring module, and a transducer/data-logger monitoring module; and   downhole injection tooling, including an injection assembly further comprising a spring-loaded nozzle, wherein the system creates a dense fracture network with a radius of influence of about 12 to 15 feet and with about 2 to about 3 order of magnitude increase in subsurface flow rates.   
     
     
         12 . A method of using a system for viscosity differential fracturing of ground comprising the steps of:
 pneumatic fracturing for about 5 to about 15 seconds using a low-viscosity fluid; and hydraulic fracturing using a fluid of greater viscosity than the low-viscosity fluid.   
     
     
         13 . The method of  claim 12 , wherein the pneumatic fracturing step comprises the use of gas. 
     
     
         14 . The method of  claim 13 , wherein the pneumatic fracturing step comprises the use of nitrogen gas. 
     
     
         15 . The method of  claim 14 , wherein the initial nitrogen gas pressure is between about 350 to about 405 pounds per square inch. 
     
     
         16 . The method of  claim 14 , wherein the maintenance nitrogen gas pressure is at least about 50 pounds per square inch, but not more than about 500 per square inch. 
     
     
         17 . The method of  claim 16 , wherein the maintenance nitrogen gas pressure is between about 200 to about 370 pounds per square inch. 
     
     
         18 . The method of  claim 14 , wherein the initial nitrogen gas flow rate is at least about 250 standard cubic feet per minute, but not more than 2,400 standard cubic feet per minute. 
     
     
         19 . The method of  claim 18 , wherein the initial nitrogen gas flow rate is between about 1,500 to about 2,400 standard cubic feet per minute. 
     
     
         20 . The method of  claim 12 , wherein the hydraulic fracturing step comprises the use of water. 
     
     
         21 . The method of  claim 12 , wherein the hydraulic fracturing step comprises the use of a proppant slurry of water, guar, and sand. 
     
     
         22 . The method of  claim 21 , wherein the proppant slurry pressure is at least about 20 pounds per square inch, but not more than 500 pounds per square inch. 
     
     
         23 . The method of  claim 22 , wherein the proppant slurry pressure is between about 80 to about 190 pounds per square inch. 
     
     
         24 . The method of  claim 21 , wherein the proppant can be injected at a flowrate of at least about 5 gallons per minute, but not more than about 25 gallons per minute. 
     
     
         25 . The method of  claim 12 , wherein the method comprises cycling between the pneumatic fracturing step and the hydraulic fracturing step through at least one cycle. 
     
     
         26 . The method of  claim 25 , wherein the method comprises cycling between the pneumatic fracturing step and the hydraulic fracturing step for a plurality of cycles. 
     
     
         27 . The method of  claim 25 , wherein the cycling step is electronically programmable by a computer program. 
     
     
         28 . The method of  claim 26 , wherein the cycling step is electronically controlled by a computer program.