Classifications

• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
  • E21B43/25—Methods for stimulating production
  • E21B43/26—Methods for stimulating production by forming crevices or fractures
  • E21B43/2605—Methods for stimulating production by forming crevices or fractures using gas or liquefied gas
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
  • E21B43/25—Methods for stimulating production
  • E21B43/26—Methods for stimulating production by forming crevices or fractures
  • E21B43/2607—Surface equipment specially adapted for fracturing operations

Definitions

• an apparatus for the supply of inert gas at a well site comprising one or more pressure vessels containing liquefied inert gas, a heat exchanger, one or more units of fracturing equipment connected to a manifold, a submersible pump in each of the one or more pressure vessels, each submersible pump being connected to supply liquefied inert gas to a supply line that passes through the heat exchanger and the supply line being connected to supply inert gas vaporized by the heat exchanger to the manifold.
• FIG. 1 is a piping and instrumentation diagram of apparatus for the supply of inert gas at a well site
• Fig. 2 shows a proportional valve arrangement for use in the apparatus of Fig. 1.
• an apparatus for the supply of inert gas at a well site includes one or more pressure vessels 10 containing liquefied inert gas that are supplied from an inert gas source 31.
• the vessels 10 may have a much smaller volume than the source 31.
• the liquefied inert gas may be for example nitrogen or argon.
• inert is meant that the gas is sufficiently non-reactive as to be useful for fire prevention and suppression.
• Submersible pumps 11 in each of the pressure vessels 10 are connected via one or more liquid supply lines 12 to supply liquefied inert gas to a supply line 14 that passes through a heat exchanger 16.
• the supply line 14 carries inert gas vaporized by the heat exchanger to a manifold 18.
• the manifold 18 supplies one or more units of fracturing equipment through lines 19 and proportional valve arrangements 38.
• the fracturing equipment may be for example a blender 20 for proppant addition and bulkers 22 for supply of fracturing fluid such as LPG for use in an LPG fracturing process.
• An exemplary valve arrangement 38 is shown in Fig. 2, which may be used for each valve arrangement 38.
• the exemplary valve arrangement 38 of Fig. 2 comprises a proportional valve 382, which is
• Valves 390 and 392 may be used to isolate the proportional valve 382, and a pressure safety valve 394 is also provided on the equipment side of the valve arrangement 38.
• the vaporized inert gas may be used as a source of power for the pneumatic control 388.
• the heat exchanger 16 comprises a chamber with a fan 24 for blowing ambient air across the supply line 14, which follows a path through the heat exchanger 16 that is typical of heat exchangers.
• One or more heaters such as electric heaters 26 powered by respective power supplies 28 are provided on the supply line 14 after the heat exchanger 16.
• the heaters 26 may not be required in all embodiments, but are useful for increasing gas pressure in cold climates, such as northern parts of North America.
• Gas pressure and flow rates of gas to the process equipment 20, 22 is monitored and the pump rates of the submersible pumps 11 , the fan speed of the fan 24 and the electrical heat produced by the heaters 26 is controlled to maintain an adequate pressure of inert gas to the process equipment 20, 22.
• the pumps 11 may be for example progressive cavity pumps with a 160 psig sump rating.
• Inert gas in liquid form is loaded into the pressure vessels 10 through lines 30 from an inert gas source 31 , which may comprise one or more N2 transport trailers or trucks.
• the vessels 10 may be drained through lines 32 and valves 33, or vented through vent 66, which may for example be a return to the N2 source 31 for example the top of a nitrogen transport truck or trailer.
• a surge connection chamber 34 may be provided on the liquid supply line 14.
• the heat exchanger 16 may be a commercially available heat exchanger such as a Model AF100A-32H.
• An automated bleed valve 36 may be provided to reduce pump back pressure on start up.
• the supply line 14 may be a 1 1 ⁇ 2 inch supply line when it carries liquid, increasing to a 3 inch, 300 psig to 320 psig main gas line after the heat exchanger 16.
• the heaters 26 may for example be powered by a 480 VAC/3 phase power supply 28 and the heaters 26 may bel 80 kW heaters.
• Pressure to a blender for an example of LPG fracturing may be at 280 psig through a 2 inch line, and for the bulkers 200 psig through a 2 inch line.
• the proportional valves 38 may use for example pneumatically operated and electrically controlled valves 382. Duplicate equipment is use for redundancy. Flow rates from pumps and heater settings are maintained automatically to maintain the proper flow for intended uses to keep system pressure delivered through hose reels to the blender(s) and bulkers.
• Pressure for the operation of the system is mainly provided by the submersible pumps 11.
• Pressure of gas supplied along the main flow line 14 is monitored by pressure transmitter 37 and pressure on the lines 19 to the fracturing equipment 20, 22 is monitored by pressure transmitters 42.
• the pressure transmitters 42 may be located elsewhere such as on the equipment 20, 22 or on the vaporizer side of the lines 19.
• an operating pressure for the fracturing equipment 20, 22 is established and pressure increased or decreased by changing the pump speed of the submersible pumps 11 to maintain sufficient total pressure on the line 14 (sensed at 37).
• the pressure on each line 19 is adjusted by controlling flow through the proportional valves 38.
• Temperature of the gas in the line 14 is also sensed with temperature transmitter 44 and if the temperature is too low, the heaters 26 are activated to heat the gas in the line 14.
• Temperature transmitters 46 in the heaters 26 and also at the outlets from the heaters 26 are used to monitor the increase of heat of the gas in line 14 and to ensure that the temperature of the gas from the heaters 26 does not reach too high a value. Internal temperatures sensors in the heaters 26 may also be used to monitor overheating of the heaters 26. Temperature transmitters 48 may be used for some embodiments of pumps 11 to ensure that fluid in the pressure vessels 10 is cold enough that vanes of the pumps 11 clear the pressure vessel walls. The vessels 10 may be charged from a liquid nitrogen source 31 to ensure that the temperature of the fluid in the vessels 10 is cold enough for start up. Temperature transmitter 50 monitors temperature of liquid nitrogen flowing into the heat exchange 16.
• a controller (not shown) is used to send appropriate control signals to the pumps 11, heaters 26 and proportional valves 38 based on inputs from the transmitters 37, 42, 44, 46, 48 and 50.
• Various conventional pressure safety valves (not shown) are used throughout the system according to conventional safety practice. Flow in the various lines is also controlled by various motor controlled valves and check valves 61-71, 382, 390 and 392 by the controller (not shown).
• the fracturing equipment including the blender 20 and bulkers 22 are installed at the well site along with the vaporizing equipment disclosed in this document, and the connections, represented by the lines in the figure, are made up between the equipment.
• Standard safety procedures for pressurized equipment are followed including the establishment of a safe zone.
• Vessels 10 are charged from inert gas source 31 through lines 30 by opening valves 61, 62 and 63. Pressurized fluid may be vented when required from the vessels 10 through valves 64 and 65 and conventional vent 66. Temperature of fluid in the vessels 10 is monitored using temperature transmitters 48 and the pumps only activated when the temperatures are suitable for equipment operation.
• valves 61-65 remain open (the N2 source 31 is the main supply), valves 36 and, depending on whether one or both pumps 11 are used and whether one, both or neither of the heaters 26 are used, one or both of valves 66 and 67 are opened, one or both of the valve sets including valves 68, 69 and valves 70, 71 are opened and one or both of pumps 11 are started to establish flow through the heat exchanger 16. Pressure builds up in line 14 until pressure sensed by pressure transmitter 37 reaches a desired level while valves 390 are closed.
• valves 390 and 392 When the fracturing equipment 20, 22 is ready to receive pressure, the valves 390 and 392 may be opened, the proportional valves 382 set at a suitable opening to produce a desired pressure in the respective lines 19, and pressure supplied to the fracturing equipment 20, 22 may be monitored using pressure transmitters 42. Pump rate of the pumps 11 may be adjusted to provide a desired pressure at pressure transmitters 42. The process may be automated or manual, but automated is preferred.

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
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• Mining & Mineral Resources (AREA)
• Physics & Mathematics (AREA)
• Environmental & Geological Engineering (AREA)
• Fluid Mechanics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)

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Cited By (5)

Citations (2)

• 2013
  • 2013-05-08 WO PCT/CA2013/050357 patent/WO2013170375A1/fr not_active Ceased

Patent Citations (2)

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