Propellant Completions

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Propellant Completions
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Principles - HEGF, etc.

• The pressure used for fracturing is provided by
  the rapid combustion (burning) of propellant in
  the wellbore, which generates large quantities of
  CO2 gas. When this pressure exceeds the in-situ
  stresses, the rock fails in tension, and the high
  velocity gasses erode the face of the subsequent
  fractures. The operation may be conducted in both
  open and cased wellbores.

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Tradenames

• The technique is known by several generic names,
  such as Dynamic Gas Pulse Loading
  (Servo-Dynamics), High Energy Gas Frac (Sandia
  National Laboratories), and Controlled Pulse
  Fracturing (Mobil Research and Development
  Corporation).
• Stimgun and Stimtube (MOC)

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Explosive Stimulation (Well Shooting)

• Liquid or solidified nitroglycerin - since
  1800s.
• The intended to fracture or "rubbilize" the rock
  to alter permeability near the wellbore.
• Brief, extremely high and compressive pressure
  pulse, or shock wave is generated, which far
  exceeds the tensile strength of the formation
  rock.

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Explosive Stimulation (Well Shooting)

• The high pressures of the detonation cause the
  rock to yield and compact.
• After the stress wave passes, the rock unloads
  elastically, leaving an enlarged, deformed
  wellbore, a zone of compacted rock and a region
  of greater compressive stress. This crushed
  region contains a substantial quantity of fines,
  which reduce permeability and productivity around
  the wellbore.

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Propellant Technology

• Explosives and propellants have similar energy
  contents, but different ingredients.
• Both release energy as they "burn", and the type
  of energy released is directly related to the
  rate at which they chemically convert into gas.
• For inducing multiple, radial fractures, the
  rate at which the borehole is pressurized is the
  controlling factor.
• Peak pressure is important, but secondary.

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Principles

• A burst of high-pressure gas or a fluid "spear"
  is driven into the perforation at extremely high
  velocities - to remove crushed-zone damage and to
  create short fractures in the formation.
• Trade literature suggests that this can result in
  negative skin.
• "Cleaner perfs mean reduced treating pressures -
  500 to 1,300 psi lower than for similar wells
  perforated in an underbalanced condition.
• Significantly lower treating pressures mean
  significantly lower treatment costs."

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StimgunTM

• Propellant sleeve over a conventional assembly.
• When the guns detonated, the propellant sleeve is
  ignited instantly, producing a burst of
  high-pressure gas.
• This gas enters the perforations, breaking
  through any damage around the tunnel, creating
  fractures in the formation.
• As the gas pressure in the wellbore dissipates,
  the gas in the formation surges into the wellbore
  carrying with it damaging fines.
• StimGun, StimTube and POWRPERF are service
  marks/trademarks of Marathon Oil Company

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The StimGun assembly used in the Mara-Stim
process

• The propellant is ignited by the pressure and
  shock wave of the shaped charges as they
  penetrate the gun, casing and formation.
• The propellant sleeve, on initial inspection,
  would appear similar to a piece of PVC pipe held
  in position by slightly larger end subs on the
  carrier.

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The Players (Stimgun)

• Marathon Oil Company
• Owen Oil Tools, Inc. (manufactures the StimGun
  and the StimTube Tool)
• HTH Technical Services, Inc.
• Computalog Ltd.
• Halliburton Energy Services, Inc.
• Baker-Atlas

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The StimTube Tool

• Same solid propellant technology as StimGun tool
• StimTube tool creates a surge of high-pressure
  gas downhole. The surge can clean up damage and
  initiate fractures in perforated cased and open
  hole wells.
• Runs on standard tubing-conveyed, electric line
  or slickline equipment.

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The StimTube Tool

• Positioned across the formation of interest.
• Ignition over the tool's entire length. The burn,
  from inside out, produces constantly increasing
  gas volumes.
• Fractures are initiated.
• As wellbore pressure declines after the burn, gas
  surges back out of the formation, carrying
  damaging fines with it, providing enhanced
  communication between the formation and wellbore.

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The PerfStim Process

• Halliburtons extreme overbalanced technique
• In the PerfStim process, an extreme overbalanced
  condition is created - pressure gradients of at
  least 1.4 psi/ft (31 kPa/m).
• A small volume (usually no more than a 300-ft
  column) of non-damaging fluid is placed above the
  gun, then pressured with nitrogen. If needed, a
  liquid can be bullheaded on top of the nitrogen
  column.

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The PerfConSM Process

• Extreme overbalance technology to perforate and
  inject a Halliburton sand consolidation resin
• When the guns fire, the resin surges into the
  formation around the perforations.
• Pump catalyst to set the resin.
• The initial high-pressure, high-flow-rate surge
  removes debris from the perforation tunnel and
  crush zone.
• Can be used through existing perforations.

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POWR?PERFSM

• The POWR?PERFSM process incorporates an agent
  that scours the perforations to remove the
  crushed zone damage, often producing negative
  skin.

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KISS Charge vs. Big-Hole Charge

• Designed to just penetrate the formation while
  the high pressure gas breaks through the crushed
  zone in the tunnel and creates fractures in the
  formation.
• KISS charges created holes in the casing that
  were equal to or larger in diameter than those
  created by conventional big-hole perforating
  charges.
• Perforation depth was reduced, so there was far
  less damage to the formation as well as a
  significantly reduced crushed zone (less than
  one-third of a conventional big-hole charge).

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Servo-DynamicsDGPL/STRESSFRAC

• Produces fractures extending several feet.
• Restricts vertical fracture growth
• Multiple zones without the need for mechanical
  isolation.
• under non-damaging fluids, such as liquid CO2,
  methanol, diesel fuel, kerosene distillates, or
  other similar liquids
• multiple fractures which intercept and connect
  with the natural fracture pattern
• in single run lengths up to 304.80 m (1,000 ft.)
• in horizontal wells in open hole, pre-perforated
  liners, cemented and perforated casing. tubing
  conveyed, with or without packers, and with or
  without tubing anchors