2 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.
3 TradenamesThe 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)
4 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.
5 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.
6 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.
8 PrinciplesA 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 to 1,300 psi lower than for similar wells perforated in an underbalanced condition.Significantly lower treating pressures mean significantly lower treatment costs."
9 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
10 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.
12 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
13 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.
14 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.
15 The PerfStim™ Process Halliburton’s 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.
16 The PerfConSM ProcessExtreme overbalance technology to perforate and inject a Halliburton sand consolidation resinWhen 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.
17 POWRPERFSMThe POWRPERFSM process incorporates an agent that scours the perforations to remove the crushed zone damage, often producing negative skin.
18 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).
19 Servo-Dynamics DGPL®/STRESSFRAC® Produces fractures extending several feet.Restricts vertical fracture growthMultiple zones without the need for mechanical isolation.under non-damaging fluids, such as liquid CO2, methanol, diesel fuel, kerosene distillates, or other similar liquidsmultiple fractures which intercept and connect with the natural fracture patternin single run lengths up to 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