WO2012054139A2 - Procédés d'établissement de réseau de fractures souterrain - Google Patents

Procédés d'établissement de réseau de fractures souterrain Download PDF

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Publication number
WO2012054139A2
WO2012054139A2 PCT/US2011/049579 US2011049579W WO2012054139A2 WO 2012054139 A2 WO2012054139 A2 WO 2012054139A2 US 2011049579 W US2011049579 W US 2011049579W WO 2012054139 A2 WO2012054139 A2 WO 2012054139A2
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WIPO (PCT)
Prior art keywords
zone
fractures
subsurface formation
wellbore
along
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PCT/US2011/049579
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English (en)
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WO2012054139A3 (fr
Inventor
Abdel Wadood M. El-Rabaa
Leonard V. Moore
Michael E. Mccraken
Chris E. Shuchart
Pavlin Entchev
Nancy H. Choi
Stephen Karner
Jose Oliverio Alvarez
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Exxonmobil Upstream Research Company
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Application filed by Exxonmobil Upstream Research Company filed Critical Exxonmobil Upstream Research Company
Priority to DE112011103548T priority Critical patent/DE112011103548T5/de
Priority to US13/825,796 priority patent/US20130220604A1/en
Priority to CA2814750A priority patent/CA2814750A1/fr
Priority to AU2011318546A priority patent/AU2011318546A1/en
Publication of WO2012054139A2 publication Critical patent/WO2012054139A2/fr
Publication of WO2012054139A3 publication Critical patent/WO2012054139A3/fr

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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
    • 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
    • E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
    • E21B49/006—Measuring wall stresses in the borehole

Definitions

  • the present inventions relate to the formation of artificial fractures in a subsurface formation. More specifically, the inventions relate to the manipulation of in situ stresses within a subsurface formation in order to control the propagation of fractures from wells completed in the formation.
  • Natural resources sometimes reside in subsurface formations in the form of a fluid. Such natural resources include oil, gas, coal bed methane, and geothermal steam. Typically, such natural resources reside many feet below the surface.
  • one or more wellbores is formed from the surface down to the depth of the subsurface formation.
  • the wellbore provides fluid communication between the surface and the subsurface formation. Fluids may then be transported to the surface, either by means of reservoir pressure, by means of artificial pressure, through pumping, or by combinations thereof.
  • rock matrices have very limited permeability.
  • shale gas reservoirs found in North America. These include the Marcellus shale formation, the Barnett shale formation, the Haynesville shale formation, and the Horn River shale formation.
  • Another example of a formation where the rock matrix has low permeability is the so-called tight gas sandstone and siltstone intervals found in the Piceance Basin.
  • Hydraulic fracturing is a technique involving the injection of fiuid under high pressure into a selected subsurface zone. The fiuid is pumped into the wellbore, and then injected through perforations previously shot in production casing and into the surrounding rock matrix. Typically, the rock matrix is a hydrocarbon bearing formation. The fluid is injected at a pressure sufficient enough to create fractures within the rock matrix extending from the perforations. This pressure is sometimes referred to as a "parting" pressure or a "fracturing" pressure.
  • the fluid includes a proppant used to hold the fractures open after the fluid pressure is relieved.
  • a proppant used to hold the fractures open after the fluid pressure is relieved.
  • a problem encountered with hydraulic fracturing is that the fractures do not always propagate from the wellbore in a direction that is optimal for well productivity or injection. Further, fractures may propagate from different zones in parallel orientations. This means that the fractures do not interconnect, and the artificial fluid channels created for fluid flow to the wellbore remain somewhat isolated.
  • the orientation of fractures in an underground formation is generally controlled by the in situ stress of the formation. It is known that subsurface formations are subjected to three principal stresses. These represent a vertical stress and two orthogonal horizontal stresses. When a formation is hydraulically fractured, the created fractures should propagate along a path of least resistance. Under principals of geomechanics, the path of least resistance should be in a direction that is perpendicular to the direction of least principal stress.
  • the '881 patent also suggested a modified arrangement to this process. The operator would first determine whether the stress field around a first hydraulic fracture would be altered to allow a reversal of the in situ stresses. The anticipated initial fracture orientation of the hydrocarbon-bearing formation is then determined. The formation is then perforated in a direction parallel to the anticipated fracture orientation, and also perforated in a direction perpendicular to the anticipated fracture orientation. The formation is then fractured in each of the two directions simultaneously.
  • U.S. Pat. Publ. No. 2009/0095482 and U.S. Pat. Publ. No. 2009/0194273 describe a method for orchestrating multiple subsurface fractures at multiple well locations in a region. This is done by flowing a well treatment fluid from a centralized well treatment fluid center. In operation, a fracture is formed at a first well location, and the effects of that fracture on stress fields within the formation are measured. Sensors disposed about the region are adapted to output effects on the stress fields. This process is then repeated for subsequent fractures. The location and orientation of subsequent fractures are based on the combined stress effects on the stress fields as a result of the prior fractures. [0014] The above publications also disclose a method of servicing multiple well locations.
  • the method includes the step of configuring a central location for the distribution of "well development task fluids to centralized service factories" through fluid lines.
  • the method also includes preparing the treatment fluids at the centralized service factories, and treating wells with the treatment fluids according to well development tasks associated with each well.
  • U.S. Pat. No. 4,724,905 also entitled “Simultaneous Hydraulic Fracturing,” discloses the use of hydraulic fracturing in one well to control the direction of propagation of a second hydraulic fracture in a second well located nearby.
  • the first well is fractured, with the fractures generally forming parallel to the fractures in the natural fracture system.
  • the hydraulic pressure is maintained in the first well, and another hydraulic fracturing operation is conducted at the second well within a zone of anticipated in situ stress alteration caused by the first hydraulic fracture.
  • the second hydraulic fracture propagates at an angle that is substantially perpendicular to the first hydraulic fracture.
  • a method of creating a network of fractures in a reservoir is first provided.
  • the reservoir has an in situ stress field.
  • the method has particular application to subsurface rock formations having a permeability that is less than 10 millidarcies.
  • the method includes designing a desired fracture network system.
  • the fracture network system represents a system of fractures or, alternatively, sets of fractures.
  • the fractures are designed to interconnect within the reservoir.
  • the step of designing a desired fracture network is done using geomechanical simulation, which involves use of a software program and a processor.
  • the method also includes determining required in situ stresses to create the desired fracture network within the reservoir. Determining required in situ stresses may be done by, for example, (i) reviewing downhole pressure measurements from existing wells, (ii) reviewing micro-seismic and/or tiltmeter monitoring conducted in existing wells, (iii) conducting downhole stress modeling, or (iv) combinations thereof.
  • the method further includes designing a layout of wells to alter the in situ stresses within the stress field.
  • the layout may refer to the location of wellheads at the surface, the orientation of wellbores along the reservoir, the completion architecture, or combinations thereof.
  • the method additionally includes injecting a fracturing fluid under pressure into the reservoir.
  • the purpose is to create an initial set of fractures within the reservoir.
  • the fluid may be injected through wells completed for the production of hydrocarbon fluids. Alternatively or in addition, the fluid may be injected through wells completed for the injection of fluids, such as brine.
  • the method also includes monitoring the in situ stresses within the stress field. Monitoring may be done by, for example, (i) reviewing downhole pressure measurements from wells in the field, (ii) reviewing micro-seismic and/or tiltmeter monitoring conducted in wells in the field, (iii) conducting downhole stress modeling, or (iv) combinations thereof.
  • the method additionally includes updating the geomechanical simulation based on the monitored in situ stresses. Further, the method includes designing a program of modifying the in situ stress within the stress field. The step of designing a program is also done using geomechanical simulation.
  • the method further includes modifying the in situ stresses within the stress field.
  • the modifying step is performed at least in part by producing hydrocarbon fluids from the reservoir.
  • the modifying step is performed at least in part by injecting fluids into the reservoir. This injection is for the purpose of increasing pore pressure, and not to further fracture the reservoir. The injection of fluids may take place through a plurality of wells either simultaneously, or in stages such that fluid is injected into two or more wells sequentially.
  • Modifying the in situ stresses may further comprise (i) specifying a length of time for injecting for selected wells, (ii) specifying a viscosity of fluid for injection into selected wells, (iii) modifying a temperature of the reservoir, or (iv) combinations thereof.
  • modifying the in situ stresses may comprise providing new perforations into the reservoir from selected wellbores, with the perforations being shot at a non-transverse angle relative to the wellbores.
  • the method then includes injecting a fracturing fluid under pressure into the reservoir in order to expand upon the initial set of fractures and to create the desired fracture network.
  • injecting a fluid under pressure into the reservoir comprises injecting a fluid through a plurality of wells that are part of the layout of wells.
  • at least two wells in the layout of wells are completed for the production of hydrocarbon fluids.
  • the network of fractures is designed to optimize production of the hydrocarbon fluids.
  • injecting a fracturing fluid under pressure into the reservoir comprises injecting the fluid through the at least two wells completed for the production of hydrocarbon fluids.
  • the method then further comprises producing hydrocarbon fluids from the wells completed for the production of hydrocarbon fluids after the initial set of fractures is created.
  • At least two wells in the layout of wells are completed for the injection of fluids as part of enhanced hydrocarbon recovery.
  • the fluids may represent an aqueous fluid such as brine.
  • injecting a fluid under pressure into the reservoir comprises injecting the fluid through selected wells completed for the injection of fluids.
  • At least two wells in the layout of wells are completed for the production of geothermally-produced steam.
  • the network of fractures is designed to optimize heat transfer for geothermal applications.
  • Injecting a fluid under pressure into the reservoir comprises injecting the fluid through selected wells completed for the production of the geothermally-produced steam.
  • At least two wells in the layout of wells are completed for the injection of acid gases.
  • injecting a fluid under pressure into the reservoir comprises injecting the fluid through selected wells completed for the injection of acid gases.
  • the acid gases may comprise, for example, primarily carbon dioxide.
  • the carbon dioxide may be injected as part of an enhanced hydrocarbon recovery project. Alternatively, the carbon dioxide may be injected as part of a sequestration operation.
  • the network of fractures is designed to optimize C0 2 storage capacity.
  • at least two wells in the layout of wells are completed for the injection of drill cuttings. In this instance, injecting a fluid under pressure into the reservoir comprises injecting the fluid through selected wells completed for the injection of drill cuttings.
  • a method of producing hydrocarbons from a subsurface formation is also provided herein.
  • the formation has a permeability less than about 10 millidarcies.
  • the method includes providing a wellbore in the subsurface formation.
  • the wellbore has been formed as a deviated wellbore. Further, the wellbore has been perforated within the subsurface formation along at least a first zone and a second zone.
  • the method also includes fracturing the subsurface formation along the first and second zones. This forms a plurality of fractures extending from the wellbore in an approximately vertically oriented plane that is substantially perpendicular to the direction of least principal or minimum stress.
  • the deviated wellbore is completed as a substantially horizontal wellbore within the subsurface formation.
  • the fractures extend substantially transverse to the wellbore in an approximately vertically oriented plane, sometimes referred to herein as vertical fractures, that is substantially perpendicular to the direction of least principal or minimum stress.
  • the method then includes producing hydrocarbon fluids through the vertical fractures along the first and second zones.
  • the method further includes monitoring the wellbore.
  • the wellbore is monitored to determine when a change in orientation of the maximum principal stress occurs within the subsurface formation along the first and second zones.
  • Monitoring the wellbore may comprise (i) determining when a designated volume of hydrocarbon fluids have been produced from the wellbore; (ii) determining when a designated reduction in reservoir pressure within the subsurface formation has taken place; (iii) determining when a selected period of time of production has taken place; (iv) determining whether micro-seismic and/or tiltmeter readings indicate a change in in situ stresses; (v) or combinations thereof.
  • the method also includes injecting a fracturing fluid into the subsurface formation.
  • the fluid is injected through perforations in the first and second zones.
  • the new fractures are still located within an approximately vertically oriented plane, but the plane of the new fractures is at an angle to the vertically oriented planar network of the originally created fractures.
  • the method further includes producing hydrocarbons through the first set of new fractures and through the vertical fractures along the first and second zones.
  • the wellbore has further been perforated within the subsurface formation along a third zone.
  • the wellbore has further been perforated within the subsurface formation along a third zone.
  • fracturing the subsurface formation further comprises fracturing the subsurface formation along the third zone to form additional vertical fractures extending from the wellbore;
  • producing hydrocarbon fluids through the vertical fractures further comprises producing hydrocarbon fluids along the third zone;
  • monitoring the wellbore further comprises monitoring the wellbore to determine when a change in maximum principal stress may occur within the subsurface formation along the third zone; • injecting a fracturing fluid into the subsurface formation to create the first set of new fractures further comprises injecting a fracturing fluid through perforations in the third zone; and
  • • producing hydrocarbons through the first set of new fractures further comprises producing hydrocarbons through the vertical fractures along the third zone.
  • the method further comprises injecting a fracturing fluid into the subsurface formation through perforations in the first, second, and (optional) third zones.
  • This creates a second set of new fractures within the subsurface formation that at least partially extend from the (i) vertical fractures, (ii) the first set of new fractures, or (iii) both.
  • the fractures in the second new set of fractures extend along a plane that may be substantially transverse to, or at least at an angle to, the vertical fractures.
  • the method then further includes producing hydrocarbons through (i) the second set of new fractures, (ii) the first set of new fractures, and (iii) the vertical fractures along the first, second, and (optional) third zones.
  • the perforations along the first zone, the second zone, and the third zone are separated.
  • separation may be by a distance of between about 20 feet (6.1 meters) and 500 feet (152.4 meters).
  • the vertical fractures may extend a distance of about 100 feet (30.5 meters) to 500 feet (152.4 meters) from the wellbore.
  • the method further comprises:
  • the method includes providing a wellbore in the subsurface formation.
  • the wellbore has been completed as a deviated wellbore. Further, the wellbore has been perforated within the subsurface formation along at least a first zone and a second zone.
  • the method also includes fracturing the subsurface formation along the first and second zones. This forms a plurality of fractures formed in a vertical plane, referred to herein as vertical fractures, extending from the wellbore.
  • vertical fractures formed in a vertical plane, referred to herein as vertical fractures, extending from the wellbore.
  • the deviated wellbore is completed as a substantially horizontal wellbore within the subsurface formation.
  • the vertical fractures extend substantially transverse to the wellbore.
  • the method then includes producing hydrocarbon fluids through the vertical fractures along the first and second zones.
  • the method also includes injecting a fluid into the subsurface formation.
  • the fluid is injected through perforations in the second zone. This serves to raise the reservoir pressure in the subsurface formation along the first zone, and also causes a change in the in situ stresses within the subsurface formation along the first zone. It is noted that the fluid is not injected at a pressure in excess of the formation parting pressure.
  • the method further includes injecting a fluid into the subsurface formation through perforations in the first zone. In this instance, fluid injection causes a propagation of fractures in the subsurface formation along the first zone at least partially towards the second zone.
  • the method also includes producing hydrocarbons through the perforations along the first zone.
  • the method may further include producing hydrocarbons through the perforations along the second zone along with the production of hydrocarbons from the first zone.
  • the method further comprises monitoring the wellbore to determine when a change in maximum principal stress may occur within the subsurface formation along the first zone as a result of injecting the fluid into the second zone.
  • Monitoring the wellbore may be done by (i) determining when a designated volume of hydrocarbon fluids have been produced from the first zone; (ii) determining when a designated reduction in reservoir pressure within the subsurface formation along the first zone has taken place; (iii) determining when a selected period of time of production has taken place; (iv) determining whether micro-seismic and/or tiltmeter readings indicate a change in in situ stresses; (v) determining when a selected volume of fluid has been injected into the subsurface formations through the perforations in the second zone; or (vi) combinations thereof.
  • the wellbore has further been perforated within the subsurface formation along a third zone.
  • the wellbore has further been perforated within the subsurface formation along a third zone.
  • fracturing the subsurface formation further comprises fracturing the subsurface formation along the third zone to form additional vertical fractures extending from the wellbore;
  • producing hydrocarbon fluids through the vertical fractures further comprises producing hydrocarbon fluids along the third zone;
  • injecting a fluid into the subsurface formation through perforations in the second zone further raises reservoir pressure in the subsurface formation along the third zone, and further causes a change in the in situ stresses within the subsurface formation along the third zone.
  • the method then further comprises:
  • the method may also include producing hydrocarbons through the perforations along the first and second zones along with the production of hydrocarbons from the third zone.
  • the perforations along the first zone, the second zone, and the optional third zone are separated.
  • separation may be by a distance of between about 20 feet (6.1 meters) and 500 feet (152.4 meters).
  • the fractures may extend a distance of about 100 feet (30.5 meters) to 500 feet (152.4 meters) from the wellbore.
  • the method further comprises:
  • the method further comprises:
  • Figure 1 is a cross-sectional view of an illustrative wellbore.
  • the wellbore has been completed as a deviated wellbore within a subsurface formation.
  • the subsurface formation contains hydrocarbon fluids.
  • Figures 2A through 2K are perspective views of a bottom portion of the wellbore of Figure 1.
  • the wellbore is divided or apportioned into three illustrative zones for the production of hydrocarbon fluids from the subsurface formation.
  • the wellbore is lined with a string of production casing.
  • FIG. 2 A the casing has been perforated in each of a first zone, a second zone, and a third zone.
  • a fracturing fluid is being injected through the perforations in the casing.
  • the subsurface formation is being fractured along the first zone, the second, and the third zone.
  • FIG. 2C vertical fractures have been formed in each of the first, second, and third zones.
  • FIG. 2D the wellbore has been placed in full production. Hydrocarbon fluids are being produced from the subsurface formation along each of the first, second, and third zones. A first zone of production is seen along each of the wellbore zones.
  • a first new set of fractures is formed in each of the first, second and third zones.
  • the new sets of fractures extend from the original vertical fractures at least partially in a direction that is transverse to the original vertical fractures.
  • FIG. 2K new intermediate perforations have been formed along the casing.
  • the illustrative perforations are oriented at an angle non-transverse to the casing.
  • the subsurface formation has also been fractured from the intermediate perforations.
  • Figures 3A and 3B are a single flowchart showing steps for performing a method of producing hydrocarbons from a subsurface formation.
  • Figures 4A through 4Q are perspective views of a bottom portion of the wellbore of Figure 1.
  • the wellbore is again divided into three illustrative zones for the production of hydrocarbon fluids from the subsurface formation.
  • the wellbore is lined with a string of production casing.
  • the casing has been perforated in each of a first zone, a second zone, and a third zone.
  • a fracturing fluid is being injected through the perforations in the casing.
  • the subsurface formation is being fractured along the first, the second, and the third zones.
  • FIG. 4D the wellbore has been placed in production. Hydrocarbon fluids are being produced from the subsurface formation along each of the first, second, and third zones. A first zone of production is seen along each of the wellbore zones.
  • first new sets of fractures have been created in the first and third zones.
  • the first new fractures propagate at least partially towards the second (intermediate) zone.
  • the new sets of fractures extend at least partially from the original vertical fractures in a direction that is at least partially transverse to the vertical fractures.
  • Figures 5 A through 5C are a single flowchart showing steps for performing a method of producing hydrocarbons from a subsurface formation.
  • Figure 6A shows a perspective view of a designed fracture network.
  • Figures 6B is another perspective view of a designed fracture network
  • Figure 7 provides a plan view of a hydrocarbon development area. A well layout and completion arrangement is set out for the creation of a fracture network and the subsequent production of hydrocarbon fluids.
  • Figure 8 is a flow chart showing steps for performing a method of creating a network of fractures in a reservoir, in one embodiment.
  • the reservoir preferably represents a rock matrix having a low permeability.
  • Figure 9 is a flow chart setting forth various steps for determining or for monitoring in situ stresses in a stress field.
  • hydrocarbon refers to an organic compound that includes primarily, if not exclusively, the elements hydrogen and carbon. Hydrocarbons generally fall into two classes: aliphatic, or straight chain hydrocarbons, and cyclic, or closed ring, hydrocarbons including cyclic terpenes. Examples of hydrocarbon-containing materials include any form of natural gas, oil, coal, and bitumen that can be used as a fuel or upgraded into a fuel.
  • hydrocarbon fluids refers to a hydrocarbon or mixtures of hydrocarbons that are gases or liquids.
  • hydrocarbon fluids may include a hydrocarbon or mixtures of hydrocarbons that are gases or liquids at formation conditions, at processing conditions or at ambient conditions (15° C and 1 atm pressure).
  • Hydrocarbon fluids may include, for example, oil, natural gas, coalbed methane, shale oil, pyrolysis oil, pyrolysis gas, a pyrolysis product of coal, and other hydrocarbons that are in a gaseous or liquid state.
  • the terms "produced fluids” and “production fluids” refer to liquids and/or gases removed from a subsurface formation, including, for example, an organic-rich rock formation. Produced fluids may include both hydrocarbon fluids and non- hydrocarbon fluids. Production fluids may include, but are not limited to, oil, pyrolyzed shale oil, gas, synthesis gas, a pyrolysis product of coal, carbon dioxide, hydrogen sulfide and water (including steam). [0100] As used herein, the term “fluid” refers to gases, liquids, and combinations of gases and liquids, as well as to combinations of gases and solids, combinations of liquids and solids, and combinations of gases, liquids, and solids.
  • gas refers to a fluid that is in its vapor phase at 1 atm and 15° C.
  • oil refers to a hydrocarbon fluid containing primarily a mixture of condensable hydrocarbons.
  • subsurface refers to geologic strata occurring below [0104]
  • zone of interest refers to a portion of a formation containing hydrocarbons.
  • the term "formation" refers to any definable subsurface region.
  • the formation may contain one or more hydrocarbon-containing layers, one or more non-hydrocarbon containing layers, an overburden, and/or an underburden of any geologic formation.
  • hydrocarbon-rich formation refers to any formation that contains more than trace amounts of hydrocarbons.
  • a hydrocarbon-rich formation may include portions that contain hydrocarbons at a level of greater than 5 percent by volume.
  • the hydrocarbons located in a hydrocarbon-rich formation may include, for example, oil, natural gas, heavy hydrocarbons, and solid hydrocarbons.
  • organic-rich rock refers to any rock matrix holding solid hydrocarbons and/or heavy hydrocarbons.
  • Rock matrices may include, but are not limited to, sedimentary rocks, shales, siltstones, sands, silicilytes, carbonates, and diatomites.
  • Organic-rich rock may contain kerogen.
  • hydraulic fracture refers to a fracture at least partially propagated into a formation, wherein the fracture is created through injection of pressurized fluids into the formation. While the term “hydraulic fracture” is used, the inventions herein are not limited to use in hydraulic fractures. The invention is suitable for use in any fracture created in any manner considered to be suitable by one skilled in the art. The fracture may be artificially held open by injection of a proppant material. Hydraulic fractures may be substantially horizontal in orientation, substantially vertical in orientation, or oriented along any other plane.
  • wellbore refers to a hole in the subsurface made by drilling or insertion of a conduit into the subsurface.
  • a wellbore may have a substantially circular cross section, or other cross-sectional shapes.
  • well when referring to an opening in the formation, may be used interchangeably with the term “wellbore.”
  • Figure 1 is a cross-sectional view of an illustrative wellbore 100.
  • the wellbore 100 defines a bore 105 that extends from a surface 101, and into the earth's subsurface 110.
  • the bore 105 preferably includes a shut-in valve 108.
  • the shut-in valve 108 controls the flow of production fluids from the wellbore 100 in the event of a catastrophic event at the surface 101.
  • the wellbore 100 includes a wellhead, shown schematically at 120.
  • the wellhead 120 contains various items of flow control equipment such as a lower master fracturing valve 122 and an upper master fracturing valve 124. It is understood that the wellhead 120 will include other components during the formation and completion of the wellbore 100, such as a blowout preventer (not shown). In a subsea context, the wellhead may also include a lower marine riser package.
  • the wellbore 100 has been completed by setting a series of pipes into the subsurface 110.
  • These pipes include a first string of casing 130, sometimes known as surface casing or a conductor.
  • These pipes also include a final string of casing 150, known as a production casing.
  • the pipes also include one or more sets of intermediate casing 140.
  • the string of surface casing 130 and the intermediate string of casing 140 are set in place using a cement sheath.
  • a cement sheath 135 is seen isolating the subsurface 110 along the surface casing 130, while a cement sheath 145 is seen isolating the subsurface 110 along the intermediate casing 140.
  • the illustrative wellbore 100 is completed horizontally. A horizontal portion is shown at 160.
  • the horizontal portion 160 has a heel 162.
  • the horizontal portion 160 also has a toe 164 that extends through a hydrocarbon-bearing interval 170.
  • the horizontal portion 160 of the wellbore 100 extends laterally through a formation 170.
  • the formation 170 may be a carbonate or sand formation having good consolidation but poor permeability. More preferably, however, the formation 170 is a shale formation having low permeability. In any instance, the formation 170 may have a permeability of less than 100 miUidarcies, or less than 50 miUidarcies, or less than 10 miUidarcies, or even less than 1 millidarcy.
  • the production casing 150 represents a liner.
  • the casing 150 does not extend back to the surface 101, but is hung from an intermediate string of casing 140 using a liner hanger 152.
  • the production casing 150 extends substantially to the toe 164 of the wellbore 100, and is cemented in place with a cement sheath 155.
  • the horizontal portion 160 of the wellbore 100 extends for many hundreds of feet.
  • the horizontal portion 160 may extend for over 250 feet, or over 1,000 feet, or even more than 5,000 feet. Extending the horizontal portion 160 of the wellbore 100 such great distances increases the exposure of the low-permeability formation 170 to the wellbore 100.
  • the production casing 150 is perforated. Perforations are shown at 157. While only three sets of perforations 157 are shown, it is understood that the horizontal portion 160 may have many more sets of perforations 157.
  • the operator may wish to stimulate the formation 170 by circulating an acid solution. This serves to clean out residual drilling mud both along the wall of the borehole 105 and into the near- wellbore region (the region within formation 170 close to the production casing 150).
  • the operator may wish to fracture the formation 170. This is done by injecting a fracturing fluid under high pressure through the perforations 157 and into the formation 170. The fracturing process creates fissures 159 along the formation 170 to enhance fluid flow into the production casing 150.
  • the wellbore 100 may be apportioned into sections or zones.
  • the horizontal portion 160 is divided into three zones 154, 156, 158. While only three zones are shown in Figure 1, it is understood that a horizontally completed wellbore may be divided into numerous additional zones.
  • Each zone may represent, for example, a length of up to about 30 meters (100 feet).
  • the operator may fracture and treat each zone 154, 156, 158 separately.
  • Figures 2A through 2K are perspective views of a bottom portion of a wellbore 200.
  • the wellbore 200 may be the bottom portion of illustrative wellbore 100 of Figure 1, in one embodiment.
  • the wellbore 200 is completed as a deviated wellbore through a subsurface formation 250.
  • the illustrative wellbore 200 is completed substantially horizontally.
  • the subsurface formation 250 represents a rock matrix having limited permeability.
  • the formation may have a permeability less than about 10 millidarcies.
  • the subsurface formation represents a hydrocarbon-producing reservoir such as a tight-gas formation, a shale gas formation, or a coal bed methane formation.
  • the reservoir may contain methane along with so-called acid gases such as carbon dioxide and hydrogen sulfide.
  • the reservoir may also incidentally contain water or brine.
  • the wellbore 200 includes a string of casing 202.
  • the casing 202 has been cemented into the formation 250.
  • a cement sheath 204 is shown cut away in each of Figures 2A through 2K.
  • the casing 202 defines an elongated tubular body forming a bore 205 therethrough.
  • the bore 205 is bifurcated into sections 240 and 245.
  • the sections 240, 245 are separated by a wall 242 so that no fluid communication exists between the sections 240, 245.
  • Each of sections 240 and 245 has a semi-circular profile. However, other profiles may be employed.
  • bifurcating the bore 205 permits the operator to alternatively produce fluids from and inject fluids into the subsurface formation 250. This may be done without running alternating strings of production tubing and injection tubing into and out of the casing 202.
  • the methods claimed below permit either the use of a bifurcated tubular body or the cyclical running of production and tubing strings. Further, the claims allow for the placement of both a tubing string and an injection string together within the bore 205 of the casing (as shown in Figures 4 A through 4Q).
  • FIG. 2A separate arrows "P” and “I” are seen.
  • Arrow “I” indicates a path of injection for fluids into the subsurface formation 250. Injection fluids may travel through section 240.
  • arrow “P” indicates a flow of production fluids from the subsurface formation 250. Production fluids may travel through section 245.
  • the wellbore 200 is divided into three illustrative zones 210, 220, 230. Each zone 210, 220, 230 is within the subsurface formation 250 and passes through hydrocarbon fluids.
  • the casing 202 has been perforated in the first zone 210, the second zone 220, and the third zone 230. Perforations in the first zone 210 are seen at 212; perforations in the second zone 220 are seen at 222; and perforations in the third zone 230 are seen at 232.
  • the perforations 212, 222, 232 extend through the casing 202 and the cement sheath 204, and place the bore 205 in fluid communication with the surrounding formation 250.
  • Figure 2B presents a next view of the wellbore 200.
  • a fracturing fluid is being injected into the subsurface formation 250. Fluid flows into section 240 in accordance with arrow "I.” From there, the fluid flows under high pressure through the perforations 212, 222, 232 in the casing 202, and into the subsurface formation 250.
  • Arrows 216 indicate the flow of fracturing fluid into the first zone 210; arrows 226 indicate the flow of fluid into the second zone 226; and arrows 236 indicate the flow of fluid into the third zone 236.
  • FIG. 2C presents a next view of the wellbore 200.
  • the fracturing fluid has created vertical fractures in each of the first 210, second 220, and third 230 zones.
  • Vertical fractures 214' are formed along the first zone 210;
  • vertical fractures 224' are formed along the second zone 220;
  • vertical fractures 234' are formed along the third zone 230. While the vertical fractures 214', 224', 234' are shown in linear form, it is understood that the fractures will actually be planar. In addition, while each of the vertical fractures 214', 224', 234' are shown in only two lines, it is understood that each zone 210, 220, 230 will most likely be fractured along more than one vertical plane.
  • fractures are referred to and illustrated as vertical fractures, that fractures tend to propagate vertically and/or horizontally perpendicular to the direction of least principal stress, the fractures together forming an approximately vertically oriented planar fracture.
  • the horizontal directions are the x and y axes and the vertical direction is defined by a z axis, and the direction of least principal stress is in the x direction, multiple fractures would form in the y-z plane.
  • FIG. 2D presents a next view of the wellbore 200.
  • the wellbore 200 has been placed in full production.
  • Hydrocarbon fluids are being produced from the subsurface formation 250 along each of the first 210, second 220, and third 230 zones. Fluids flow from the subsurface formation 250, through the vertical fractures 214', 224', 234', and through the respective perforations 212, 222, 232. From there, production fluids flow through section 245 within the casing 202, and towards the surface (not shown) according to arrow "P.”
  • each of the fractures 214', 224', 234' creates a first zone of production. This is indicated schematically in Figure 2D.
  • the first zone of production in the first zone 210 is seen at 215'; the first zone of production in the second zone 220 is seen at 225'; and the first zone of production in the third zone is seen at 235'.
  • the zones of production 215', 225', 235' remain closely tied to the fracture planes created by the vertical fractures 214', 224', 234'.
  • the wellbore 200 is monitored during production. Particularly, the wellbore 200 is monitored to determine when a change in the orientation of maximum principal stress may occur within the subsurface formation 250.
  • the wellbore 200 may be monitored in various ways. For example, monitoring the wellbore 200 may comprise determining when a designated volume of hydrocarbon fluids have been produced from the wellbore 200. Alternatively, monitoring the wellbore 200 may comprise determining when a designated reduction in reservoir pressure within the subsurface formation 250 has taken place. This may be done through reservoir simulation or may be based on experience with existing wells in the field.
  • monitoring the wellbore 200 may comprise determining when a selected period of time of production has taken place. And alternatively still, monitoring the wellbore 200 may comprise determining whether micro-seismic readings or tilt-meter readings indicate a change in in situ stresses. Combinations of these techniques are preferably employed.
  • Figure 2E presents a next view of the wellbore 200.
  • production from the wellbore 200 has been suspended. This takes place once it is determined that the orientation of maximum principal stress in the first 210, second 220, and third 230 zones has changed.
  • fluid is now being injected through the perforations 212, 222, 232 along each of the three zones 210, 220, 230 under high pressure. Fluid travels according to injection arrow "I" into the first section 240 of the casing 202. Fluid then exits the casing 202 through the perforations 212, 222, 232 according to respective fracture injection arrows 216, 226, 236.
  • Figure 2F presents a next view of the wellbore 200.
  • a first new set of fractures is formed in each of the first 210, second 220, and third 230 zones.
  • New fractures in the first zone 210 are seen at 214"; new fractures in the second zone 220 are seen at 224"; and new fractures in the third zone 230 are seen at 234".
  • the new fractures 214" in the first zone 210 largely extend from the original vertical fractures 214' in that zone 210.
  • the new fractures 224" in the second zone 220 largely extend from the original vertical fractures 224' in that zone 220.
  • the new fractures 234" in the third zone 230 largely extend from the original vertical fractures 234' in that zone 230.
  • Each of the new fractures 214", 224", 234" extends at least partially in a direction that is transverse to the respective vertical fractures 214', 224', 234'. This is because of the change in maximum principal stress within the subsurface formation 250. The result is that the complexity of the fracture network within the subsurface formation 250 has beneficially increased, even using just a single wellbore. [0138] The direction in which the new fractures 214", 224", and 234" propagate should be re-emphasized.
  • Figure 2G presents a next view of the wellbore 200.
  • the wellbore 200 has been placed back in full production.
  • Hydrocarbon fluids are again being produced from the subsurface formation 250 along each of the first 210, second 220, and third 230 zones.
  • first zone 210 fluids flow from the subsurface formation 250, through the first set of new fractures 214", through the vertical fractures 214', through the perforations 212, and into the casing 202.
  • second zone 220 fluids flow from the subsurface formation 250, through the first set of new fractures 224", through the vertical fractures 224', through the perforations 222, and into the casing 202.
  • the third zone 230 fluids flow from the subsurface formation 250, through the first set of new fractures 234", through the vertical fractures 234', through the perforations 232, and into the casing 202.
  • the fluids from the various zones 210, 220, 230 are commingled within the second section 245 of the casing 202. From there, production fluids flow toward the surface according to arrow "P.”
  • the wellbore 200 is once again monitored during production. Particularly, the wellbore 200 is monitored to determine when a change in the orientation of maximum principal stress may once again occur within the subsurface formation 250.
  • Figure 2H presents a next view of the wellbore 200.
  • production from the wellbore 200 has been suspended. This takes place once it is determined that the orientation of maximum principal stress in the first 210, second 220, and third 230 zones has once again changed.
  • fluid is now being re-injected through the perforations 212, 222, 232 along each of the three zones 210, 220, 230 under high pressure. Fluid travels according to injection arrow "I" into the first section 240 of the casing 202. Fluid then exits the casing 202 through the perforations 212, 222, 232 according to respective fracture injection arrows 216, 226, 236.
  • Figure 21 presents a next view of the wellbore 200.
  • a second new set of fractures is formed in each of the first 210, second 220, and third 230 zones.
  • New fractures in the first zone 210 are seen at 214"'; new fractures in the second zone 220 are seen at 224"'; and new fractures in the third zone 230 are seen at 234"'.
  • the new fractures 214"' in the first zone 210 largely extend from the first new fractures 214" in that zone 210.
  • the new fractures 224"' in the second zone 220 largely extend from the first new fractures 224" in that zone 220.
  • the new fractures 234"' in the third zone 230 largely extend from the first new fractures 234" in that zone 230.
  • Each of the second new fractures 214"', 224"', 234"' extends at least partially in a direction that is transverse to the respective vertical fractures 214', 224', 234'. This is because of the change in maximum principal stress within the subsurface formation 250. The result is that the complexity of the fracture network within the subsurface formation 250 has beneficially increased.
  • Figure 2J presents a next view of the wellbore 200. In Figure 2J, the wellbore 200 has been put back into production.
  • Hydrocarbon fluids are again being produced from the subsurface formation 250 along each of the first 210, second 220, and third 230 zones.
  • first zone 210 production fluids flow from the subsurface formation 250 and through the fracture network formed by fractures 214', 214", and 214"'. The production fluids then flow through the perforations 212 and into the casing 202.
  • second zone 220 production fluids flow from the subsurface formation 250 and through the fracture network formed by fractures 224', 224", 224"'. The production fluids then flow through the perforations 222 and into the casing 202.
  • third zone 230 production fluids flow from the subsurface formation 250 and through the fracture network formed by fractures 234', 234", 234"'. The production fluids then flow through the perforations 232 and into the casing 202.
  • 214"', 224"', 234"' create respective third zones of production. This is indicated schematically in Figure 2J.
  • the third zone of production in the first zone 210 is seen at 215"'; the third zone of production in the second zone 220 is seen at 225"'; and the third zone of production in the third zone is seen at 235"'.
  • the zones of production 215", 225", 235" remain closely tied to the fracture planes created by the second new fractures 214", 224", 234".
  • the third zones of production 215"', 225"', 235"' are larger than their respective second zones of production 215", 225", 235".
  • FIG. 1 presents this optional additional step.
  • new intermediate perforations have been formed along the casing 202.
  • perforations 262 are formed between the first zone 210 and the second zone 220.
  • perforations 272 are formed between the second zone 220 and the third zone 230.
  • Intermediate fractures 264 are created from perforations 262, while intermediate fractures 274 are created from perforations 274.
  • FIG. 3A and 3B present a flow chart showing steps for a method 300 of producing hydrocarbons from a subsurface formation. The method 300 generally presents the steps from Figures 2A through 2K.
  • the method 300 has application to subsurface formations with limited permeability.
  • the method 300 is particularly beneficial to formations having a permeability less than about 10 millidarcies.
  • the subsurface formation represents a hydrocarbon-producing reservoir such as a tight-gas formation, a shale gas formation, or a coal bed methane formation.
  • the reservoir may contain methane along with so-called acid gases such as carbon dioxide and hydrogen sulfide.
  • the method 300 first includes providing a wellbore in the subsurface formation. This is shown at Box 305.
  • the wellbore has been formed as a deviated wellbore.
  • the deviated wellbore is completed as a substantially horizontal wellbore within the subsurface formation.
  • Providing" a wellbore means that the wellbore has been drilled by a government, by a company, or by an individual, association, or partnership.
  • “providing” may mean that a drilling company or a service company has drilled the wellbore at the request or direction of a government, a company, or an individual, association or partnership.
  • “providing” may mean that a government, an individual, an association, or a business concern has purchased the wellbore.
  • the wellbore has been perforated within the subsurface formation along at least a first zone and a second zone.
  • the wellbore may have been perforated by the owner, the lessor, or by a service company or business affiliate on behalf of the owner or lessor.
  • the method 300 also includes fracturing the subsurface formation along the first and second zones. This is provided at Box 310. Fracturing the formation along these zones creates one or more substantially vertical fractures extending from the wellbore. Where the wellbore is substantially horizontal, the fractures will be transverse to the wellbore, oriented in a vertical plane.
  • the method 300 further includes producing hydrocarbon fluids through the vertical fractures along the first and second zones. This is seen at Box 315.
  • the vertical fractures extend a distance of about 100 feet (30.5 meters) to 500 feet (152.4 meters) from the wellbore.
  • non-hydrocarbon fluids such as water and carbon dioxide may be incidentally produced along with the hydrocarbon fluids.
  • the method 300 also includes monitoring the wellbore. This is provided at
  • Monitoring the wellbore is conducted to determine when a change in the direction or orientation of maximum principal stress may occur within the subsurface formation along the first and second zones.
  • the wellbore may be monitored in a number of different ways as discussed above.
  • the method 300 additionally includes injecting a fracturing fluid into the subsurface formation. This is provided at Box 325.
  • the fluid is preferably a hydraulic fluid such as brine. However, liquid C0 2 , foamed nitrogen, or other non-reactive fluids may also be injected.
  • the fluid is injected through perforations in the first and second zones. This serves to create first new fractures within the subsurface formation that at least partially extend from the vertical fractures along a plane that is substantially transverse to, or at least at an angle to, the vertical fractures.
  • the method 300 also includes producing hydrocarbons. This is shown at Box 325.
  • Hydrocarbon fluids are produced through the first new fractures and through the vertical fractures along the first and second zones.
  • the method 300 as described above only recites two zones. However, the method 300 may include more than two zones.
  • the wellbore is perforated to create new perforations along a third zone. This is provided at Box 335. Perforations may be provided along the first zone, the second zone, and a third zone, with the zones being separated by a distance of between, for example, about 20 feet (6.1 meters) and 500 feet (152.4 meters). The perforations along the third zone may be provided at the same time as the perforations along the first and second zones or at a later time. Accordingly, it should be understood that the methods 300 described herein may be applicable on any number of zones, including two or more zones.
  • the methods 300 described herein may be implemented on multiple zones in either a simultaneous manner or in a sequential manner.
  • the multiple zones are referenced by ordinals such as first, second, third, etc. It should be understood that reference to a first zone in an illustration is exemplary of any of the other zones and is merely for identification purposes and for description of one zone relative to another. The principles and steps of the methods described herein may be applied with respect to any one or more zones in a wellbore.
  • the method 300 may then include fracturing the subsurface formation along the third zone to form additional vertical fractures extending from the wellbore. This is seen at Box 340.
  • the method 300 also includes producing hydrocarbon fluids through the vertical fractures in the third zone. This is shown at Box 345.
  • monitoring the wellbore further comprises monitoring the wellbore to determine when a change in orientation of maximum principal stress may occur within the subsurface formation along the third zone. This is seen at Box 350.
  • production from the third zone preferably takes place simultaneously with production from the first and second zones. In other words, the production steps in Boxes 315 and 350 may overlap.
  • the method 300 also includes injecting a fracturing fluid through perforations in the third zone. This is provided at Box 355.
  • the injection step of Box 355 may be done simultaneously with the injection step of Box 325.
  • the method 300 includes producing hydrocarbons through the first set of new fractures along the third zone. This is shown at Box 360.
  • the production step of Box 360 is preferably done simultaneously with the production step of Box 330.
  • new perforations may be formed in a selected zone, as shown in Box 365 of Figure 3B.
  • the new perforations along the selected zone are shot at a non-transverse angle relative to the wellbore.
  • the subsurface formation is then fractured along the selected zone, as indicated at Box 370. Perforating the wellbore at an oriented angle helps cause fractures to form at an angle so as to intersect existing natural fractures and artificial fractures from adjoining zones.
  • the perforating 365 and fracturing 370 steps may be conducted in stages with the first, second, and third zones using multi-interval procedures.
  • the injection stages may be aided through the use of packers, fracturing ports, mechanical plugs, sand plugs, sliding sleeves, and other devices known in the art. Hydrocarbon fluids are then produced through the perforations along the selected zone.
  • the method 300 may include the step of injecting a fracturing fluid into the subsurface formation through perforations in the first, second, and third zones, thereby creating a second new set of fractures within the subsurface formation.
  • the second new fractures will at least partially extend from the vertical fractures.
  • the second new fractures will at least partially extend from the first new fractures as shown and discussed in connection with Figure 21.
  • the second new fractures extend along a plane that is at least partially transverse to the vertical fractures. Hydrocarbons are then produced through (i) the second new fractures, (ii) the first new fractures, and (iii) the vertical fractures along the first, second, and third zones.
  • the method 300 allows for the creation of a complex network of fractures using only a single wellbore.
  • the wellbore may be divided into a plurality of zones, with the zones being fractured and produced from together.
  • Figures 4 A through 4Q provide perspective views of a bottom portion of a wellbore 400.
  • the wellbore 400 may be the bottom portion of illustrative wellbore 100 of Figure 1, in one embodiment.
  • the wellbore 400 is completed as a deviated wellbore through a subsurface formation 450 having low permeability.
  • the illustrative wellbore 400 is completed substantially horizontally.
  • the wellbore 400 includes a string of casing 402.
  • the casing 402 has been cemented into the formation 450.
  • a cement sheath 404 is seen in cut-away view in each of Figures 4 A through 4Q.
  • the casing 402 defines an elongated tubular body forming a bore 405 therethrough.
  • the bore 405 employs two separate tubing strings. These represent a first string 440 used for the injection of fluids into the subsurface formation 450, and a second string 445 used for the production of fluids from the subsurface formation 450.
  • FIG. 4A separate arrows "P” and “I” are seen.
  • Arrow “I” indicates a path of injection for fluids into the subsurface formation 450. Injection fluids may travel through first tubing string 440.
  • arrow “P” indicates a flow of production fluids from the subsurface formation 450. Production fluids may travel through second tubing string 445.
  • the wellbore 400 is divided into three illustrative zones 410, 420, 430. Each zone 410, 420, 430 is within the subsurface formation 450 and passes through hydrocarbon fluids.
  • the casing 402 has been perforated in the first zone 410, in the second zone 420, and in the third zone 430. Perforations in the first zone 410 are seen at 412; perforations in the second zone 420 are seen at 422; and perforations in the third zone 430 are seen at 432.
  • the perforations 412, 422, 432 extend through the cement sheath 404 and place the bore 405 in fluid communication with the surrounding formation 450.
  • Figure 4B presents a next view of the wellbore 400.
  • a fracturing fluid is being injected into the subsurface formation 450. Fluid flows into tubing string 440 in accordance with arrow "I.” From there, the fluid flows under high pressure through the perforations 412, 422, 432 in the casing 402, and into the subsurface formation 450.
  • Arrows 416 indicate the flow of fracturing fluid into the first zone 410; arrows 426 indicate the flow of fluid into the second zone 426; and arrows 436 indicate the flow of fluid into the third zone 436.
  • FIG. 4C presents a next view of the wellbore 400.
  • the fracturing fluid has created vertical fractures in each of the first 410, second 420, and third 430 zones.
  • Vertical fractures 414' are formed along the first zone 410;
  • vertical fractures 424' are formed along the second zone 420;
  • vertical fractures 434' are formed along the third zone 430. While the vertical fractures 414', 424', 434' are shown in linear form, it is understood that the fractures will actually be planar. In addition, while the vertical fractures 414', 424', 434' are shown in only two lines, it is understood that each zone 410, 420, 430 will most likely be fractured along more than one vertical plane.
  • Figure 4D presents a next view of the wellbore 400.
  • the wellbore 400 has been placed in full production.
  • Hydrocarbon fluids are being produced from the subsurface formation 450 along each of the first 410, second 420, and third 430 zones. Fluids flow from the subsurface formation 450, through the vertical fractures 414', 424', 434', and through the respective perforations 412, 422, 432. From there, production fluids flow through tubing string 445 within the casing 402, and towards the surface (not shown) according to arrow "P.”
  • each of the fractures 414', 424', 434' creates a first zone of production. This is indicated schematically in Figure 4D as circles.
  • the first zone of production in first zone 410 is seen at 415'; the first zone of production in the second zone 420 is seen at 425'; and the first zone of production in the third zone 430 is seen at 435'.
  • the zones of production 415', 425', 435' remain closely tied to the fracture planes created by the vertical fractures 414', 424', 434'.
  • Figure 4E presents a next view of the wellbore 400.
  • FIG. 4E production from the second zone 420 has been suspended.
  • a fluid is now being injected into the subsurface formation 450 along the second zone 420. This raises the reservoir pressure along the second zone 420, and extending into the first 410 and third 430 zones.
  • the injection of fluids is indicated by injection arrow "I.”
  • the fluids travel through the first tubing string 440, and exit perforations 422 in the second zone 420.
  • the injection of fluids into the subsurface formation 450 is shown by arrows 428.
  • the wellbore 400 may be monitored. Particularly, the wellbore 400 may be monitored to determine when a change in the orientation of maximum principal stress may occur within the subsurface formation 450.
  • the wellbore 400 may be monitored in various ways. For example, monitoring the wellbore 400 may comprise determining when a designated volume of hydrocarbon fluids have been produced from the wellbore 400. Alternatively, monitoring the wellbore 400 may comprise determining when a designated reduction in reservoir pressure within the subsurface formation 450 has taken place. This may be done through reservoir simulation, or may be based on experience with existing wells in the field.
  • monitoring the wellbore 400 may comprise determining when a selected period of time of production has taken place, or when a selected period of injection has taken place. And alternatively still, monitoring the wellbore 400 may comprise determining whether micro-seismic readings or tilt-meter readings indicate a change in in situ stresses. Combinations of these techniques are preferably employed.
  • Figure 4F presents a next view of the wellbore 400.
  • fluid is now being injected into the subsurface formation 450 along the first zone 410 and the third zone 430. Fluid travels according to injection arrow "I" into the first tubing string 440 in the casing 202. Fluid then exits the casing 402 through the perforations 412 and 432 as provided by fracture injection arrows 416 and 436, respectively.
  • the fluid is injected into the subsurface formation 450 under high pressure.
  • the result is that new fractures are formed in the subsurface formation 450 along the first 410 and third 430 zones. This again is indicated by fracture injection arrows 416 and 436.
  • fluid is optionally also injected at a lower pressure into the subsurface formation 450 along the second zone 420. This is indicated by fluid injection arrows 428.
  • Figure 4G presents a next view of the wellbore 400.
  • a first new set of fractures has been created in each of the first 410 and third 430 zones.
  • the new fractures propagate at least partially towards the second (intermediate) zone 420.
  • the new sets of fractures extend from the original vertical fractures in a direction that is at least partially transverse to the vertical fractures 414', 434'.
  • New fractures in the first zone 410 are seen at 414".
  • the new fractures 414" in the first zone 410 largely extend from the original vertical fractures 414' in that zone 410.
  • New fractures in the third zone 430 are seen at 434".
  • the new fractures 434" in the third zone 430 largely extend from the original vertical fractures 434' in that zone 430.
  • Each of the new fractures 414", 434" extends at least partially in a direction that is transverse to the respective vertical fractures 414', 434'. This is because of the change in maximum principal stress within the subsurface formation 450. The result is that the complexity of the fracture network within the subsurface formation 450 has beneficially increased, even by using just a single wellbore 400.
  • FIG. 4H presents a next view of the wellbore 400.
  • the wellbore 400 has been placed back in full production.
  • Hydrocarbon fluids are again being produced from the subsurface formation 450 along each of the first 410, second 420, and third 430 zones.
  • fiuids flow from the subsurface formation 450, through the first new set of fractures 414", through the vertical fractures 414', through the perforations 412, and into the casing 402.
  • the second zone 420 production fluids flow from the subsurface formation 250, through the vertical fractures 424', through the perforations 422, and into the casing 402.
  • production fluids flow from the subsurface formation 450, through the first new set of fractures 434", through the vertical fractures 434', through the perforations 432, and into the casing 402.
  • the new fractures 414" and 434" create respective second zones of production. This is indicated schematically in Figure 4H as circles.
  • the second zone of production in first zone 410 is seen at 415"; the second zone of production in the third zone is seen at 435".
  • the zones of production 415", 435" remain closely tied to the fracture planes created by the new sets of fractures 414", 434".
  • the second zones of production 415", 435" are larger than their respective first zones of production 415', 435' (as shown in Figure 4D).
  • the second zone 420 is also in production.
  • Figure 41 presents a next view of the wellbore 400.
  • production has been suspended from the first zone 410.
  • Fluid is now being injected into the subsurface formation 450 through perforations in the first zone 410 to raise reservoir pressure in the first zone 410, and extending into the second zone 420.
  • the fluid injection is indicated by injection arrow "I” and by injection arrows 418.
  • Figure 4 J presents a next view of the wellbore 400.
  • production has been suspended from the second zone 420 as well.
  • Fluid is being injected into the formation 450 under high pressure.
  • Arrows 426 indicate a flow of fracturing fluid.
  • the step of Figure 4J takes place once it is determined that the orientation of maximum principal stress in the second zone 420 has changed.
  • the wellbore 400 may be monitored.
  • the wellbore 400 may be monitored to determine when a change in the orientation of maximum principal stress may occur within the subsurface formation 450.
  • Figure 4K presents a next view of the wellbore 400.
  • new fractures 424" have been formed in the subsurface formation 450 along the second zone 420.
  • the fractures 424" extend from the original vertical fractures 424' and at least partially towards the first zone 410.
  • the new fractures 424" extend from the original vertical fractures 424' in a direction that is at least partially transverse to the vertical fractures 424'. This is because of the change in maximum principal stress within the subsurface formation 450.
  • FIG. 4L presents a next view of the wellbore 400.
  • the wellbore 400 has been put back into production.
  • Hydrocarbon fluids are being produced from the subsurface formation 450 along each of the first 410, second 420, and third 430 zones. Fluids flow from the subsurface formation 450, through the new transverse fractures 414", 424", 434", through the vertical fractures 414', 424', 434', and through the respective perforations 412, 422, 432. From there, production fluids flow through tubing string 445 within the casing 402, and towards the surface according to arrow "P."
  • a second zone of production 425" is now provided along the second zone 420. This is indicated schematically as a circle in Figure 4L.
  • the second zone of production 425" is larger than the first zone of production seen at 425' in Figure 4H.
  • Figure 4M presents a next view of the wellbore 400.
  • production has been suspended from the third zone 430.
  • Fluid is now being injected into the subsurface formation 450 through perforations in the third zone 430 to raise reservoir pressure in the third zone 430 and extending into the second zone 420.
  • the fluid injection is indicated by injection arrow "I" and by injection arrows 438.
  • the fluids travel through the first tubing string 440, and exit perforations 422 in the second zone 420.
  • the injection of fluids into the subsurface formation 450 is shown by arrows 426.
  • production may continue in the first zone 410.
  • the production of fluids is indicated by production arrow "P.”
  • production arrow "P” As noted above, the simultaneous production and injection of fluids requires the use of separate flow paths. Such an approach is provided in Figure 4N through the separate first 440 and second 445 tubing strings.
  • Figure 40 presents a next view of the wellbore 400.
  • new fractures have again been formed along the second zone 420.
  • the new fractures are seen at 424".
  • the new fractures 424" extend from the original vertical fractures and towards the third zone 430.
  • the direction in which the new fractures 424" propagate should be re- emphasized. Because of the change in maximum principal stress within the subsurface formation 450, the new fractures 424" will at least initially extend away from the planes of the original vertical fractures 424'.
  • new fractures 424" propagate away from the vertical fractures 424', they move through a transition area of maximum principal stress and begin to bend back so that the plane formed by the new fractures 424" is in approximate alignment or parallel with the plane formed by the original vertical fractures 424'.
  • Figure 4P presents a next view of the wellbore 400.
  • the wellbore 400 has been put back into full production. Hydrocarbon fluids are being produced through the new sets of fractures 414", 424", 434" and the original vertical fractures 414', 424', 434' in each of the first 410, second 420, and third 430 zones, respectively.
  • Hydrocarbon fluids are being produced from the subsurface formation 450 along each of the first 410, second 420, and third 430 zones. Fluids flow from the subsurface formation 450, through the new transverse fractures 414", 424", 434", through the vertical fractures 414', 424', 434', and through the respective perforations 412, 422, 432. From there, production fluids flow through tubing string 445 within the casing 402, and towards the surface according to production arrow "P.”
  • Figures 4 A through 4P demonstrate steps that may be taken to increase the complexity of a fracture network in a low-permeability formation. Of importance, the steps are accomplished through a single wellbore which remains in a substantially constant state of production. As in situ stresses are changed during the course of production, additional fractures are created within the subsurface formation, creating ever-expanding zones of production. Ideally, the fractures in the various zones become interconnected.
  • the wellbore 400 with its three zones 410, 420, 430 is merely illustrative.
  • the steps presented incident to the wellbore 400 may be taken through just two adjoining zones without the presence of a third zone. Alternatively, there may be more than three zones.
  • the use of three zones and the nomenclature used to refer to the individual zones is for explanatory purposes.
  • the order of operations on the individual zones may be independent of the ordinal assigned to the zone. For example, while a step is illustrated and discussed as being performed on a first zone relative to a second zone, the step may be performed on the second relative to the first, the second relative to the third, the fifth relative to the sixth, or any other pair of adjacent zones.
  • FIG. 4Q presents this optional additional step.
  • new intermediate perforations have been formed along the casing 402.
  • perforations 462 are formed between the first zone 410 and the second zone 420.
  • perforations 472 are formed between the second zone 420 and the third zone 430.
  • Intermediate fractures 464 are created from perforations 462, while intermediate fractures 474 are created from perforations 472.
  • perforations 462, 472 be oriented at an angle that is non- transverse to the casing 402. In this way, fractures 464, 474 are at least initially propagated at an angle, and may intersect with fractures in adjoining zones.
  • Figures 4 A through 4Q present steps for a process of producing hydrocarbon fluids. The steps may be set out textually in a flowchart.
  • Figures 5A through 5C present such a flow chart, and show steps for a method 500 of producing hydrocarbon fluids.
  • the hydrocarbon fluids are produced from a subsurface formation.
  • the subsurface formation represents a reservoir containing hydrocarbon fluids.
  • the fluids may be, for example, methane and other lighter hydrocarbon fluids.
  • the reservoir may also include so-called acid gases such as carbon dioxide and hydrogen sulfide.
  • the reservoir may also incidentally contain water or brine.
  • the subsurface formation is a low-permeability formation.
  • the formation may have a permeability less than, for example, about 10 millidarcies.
  • the reservoir may be a tight-gas formation, a shale gas formation, or a coal bed methane formation.
  • the method 500 first includes providing a wellbore in the subsurface formation. This is shown at Box 505.
  • the wellbore has been completed as a deviated wellbore.
  • the deviated wellbore is a substantially horizontal wellbore within the subsurface formation.
  • the wellbore has been perforated along at least a first zone and a second zone.
  • the method 500 also includes fracturing the subsurface formation along the first and second zones. This is provided at Box 510. Fracturing the formation along these zones creates one or more substantially vertical fractures extending from the wellbore. [0222] The method 500 further includes producing hydrocarbon fluids through the vertical fractures along the first and second zones. This is seen at Box 515. In one aspect, the vertical fractures extend a distance of about 100 feet (30.5 meters) to 500 feet (152.4 meters) from the wellbore. [0223] The method 500 additionally includes injecting a fluid into the subsurface formation. This is provided at Box 520. The fluid is preferably a hydraulic fluid such as brine. However, liquid C0 2 , foamed nitrogen, or other non-reactive fluids may also be injected.
  • the fluid is preferably a hydraulic fluid such as brine. However, liquid C0 2 , foamed nitrogen, or other non-reactive fluids may also be injected.
  • the fluid is injected through perforations in the second zone. This serves to raise the reservoir pressure in the subsurface formation along the first zone. This also helps to cause a change in the in situ stresses within the subsurface formation along the first zone.
  • the fluid preferably is not injected at a parting pressure and does not extend existing fractures.
  • the method 500 may also include monitoring the wellbore. This is shown at Box 525.
  • the wellbore is monitored to determine when a change in orientation of maximum principal stress may occur within the subsurface formation along the first zone.
  • the change in maximum principal stress occurs as a result of producing fluids from the first zone and injecting the fluid into the second zone.
  • monitoring the wellbore may be monitored in a number of different ways. For example, monitoring the wellbore may comprise determining when a designated volume of hydrocarbon fiuids have been produced from the first zone or from the subsurface formation in general. Alternatively, monitoring the wellbore may comprise determining when a designated reduction in reservoir pressure within the subsurface formation along the first zone has taken place. This may be done through reservoir simulation or based on experience with existing wells in the field. Alternatively, monitoring the wellbore may comprise determining when a selected volume of fluid has been injected into the subsurface formations through the perforations in the second zone.
  • monitoring the wellbore may comprise determining when a selected period of time of production has taken place from the first zone. And still alternatively, monitoring the wellbore may comprise determining whether micro-seismic readings or tilt-meter readings indicate a change in in situ stresses. Of course, combinations of these techniques are preferably employed.
  • the method 500 further includes injecting a fluid into the subsurface formation through perforations in the first zone. This is seen at Box 530.
  • the injection of fluid in the first zone is at high pressures, and causes a propagation of fractures in the subsurface formation along the first zone.
  • the direction of maximum principal stress has been changed in the near-wellbore region along the first zone. Accordingly, the fractures tend to propagate at least partially towards the second zone.
  • the method 500 also includes producing hydrocarbons. This is shown at Box 535. Hydrocarbon fluids are produced through the perforations along the first zone. Preferably, hydrocarbon fluids are also produced through the perforations along the second zone as well. This is seen at Box 540.
  • the method 500 as described above only recites two zones. However, the method 500 may be applied to a wellbore that is perforated in more than two zones. In one aspect, the wellbore is perforated to create new perforations along a third zone. This is provided at Box 545. Perforations may be provided along the first zone, the second zone, and a third zone, with the zones preferably being separated by a distance of between about 20 feet (6.1 meters) and 500 feet (152.4 meters). As described above, the methods 500 may be performed on wellbores having multiple zones and may be performed simultaneously on more than two zones and may be performed sequentially on more than two zones. The specific manner of implementation may depend on the size of the field, the age of the field, or other factors that may become apparent to an operator. For example, the methods may be applied to more than two zones simultaneously and then later applied to still further zones.
  • the method 500 would then include fracturing the subsurface formation along the third zone to form additional vertical fractures extending from the wellbore. This is seen at Box 550.
  • the perforating 545 and fracturing 550 steps may be conducted in stages with the first, second, and third zones using multi-interval procedures known in the art of well completions.
  • the method 500 also includes producing hydrocarbon fluids through the vertical fractures in the third zone. This is shown at Box 555.
  • the producing step of Box 555 may take place with the producing step of Box 515.
  • the method 500 still includes injecting a fluid into the subsurface formation through perforations in the second zone. This was provided at Box 520.
  • the injection step of Box 520 will further raise reservoir pressure in the subsurface formation along the third zone, and will further cause a change in the in situ stresses within the subsurface formation along the third zone. This is indicated at Box 560.
  • hydrocarbon fluids continue to be produced from the third zone in accordance with the producing step of Box 555.
  • the method 500 also includes injecting a fluid into the subsurface formation through perforations in the third zone. This is provided at Box 565.
  • the injection step of Box 565 creates a first set of new fractures in the subsurface formation along the third zone. These new fractures propagate at least partially towards the second zone.
  • the method 500 next includes again producing hydrocarbon fluids from the third zone. This is provided at Box 570.
  • hydrocarbon fluids are also simultaneously produced from the first and second zones.
  • the step of producing in Box 570 may take place simultaneously with the producing step of Box 535.
  • the process of injecting fluid in one zone to increase reservoir pressure and to change in situ stresses in an adjoining zone may be applied in any order. Further, the process may be alternated such that after one zone has been re-fractured and produced, an adjoining zone may be re-fractured and produced.
  • production is temporarily suspended from the first zone. This is seen at Box 575.
  • fluid is then injected into the subsurface formation through perforations in the first zone. This is shown at Box 580. This injection is not for the purpose of creating new fractures in the first zone, but to raise reservoir pressure in the subsurface formation along the second zone. This causes a change in the in situ stresses within the subsurface formation along the second zone.
  • the method 500 then includes injecting a fluid into the subsurface formation through perforations in the second zone. This is provided at Box 585. The injection of fluids into the second zone is at high pressures, thereby causing a propagation of fractures in the subsurface formation along the second zone at least partially towards the first zone.
  • the method 500 then includes producing hydrocarbons through the perforations along the second zone. This is seen at Box 590.
  • the method 500 involves the selective injection of fluids at different pressures and in different stages. Further, the method 500 involves the production of fluids from selected zones at different stages. The steps of the method 500 may be aided through the use of packers, fracturing ports, mechanical plugs, sand plugs, sliding sleeves, and other devices known in the art.
  • the methods 300 and 500 of Figures 3A-3B and Figures 5A-5C, respectively, relate to the creation of a fracture network from a single wellbore. However, the concept of manipulating in situ stresses to increase the complexity of a fracture network may be approached on a multi-well basis.
  • FIG. 6A presents such an illustrative fracture network 600A.
  • the fracture network 600A comprises a series of interconnecting fractures 610, 620. Each of the fractures 610, 620 is oriented in a substantially vertical plane.
  • each of the fractures 610, 620 are arranged in pairs 650A.
  • Each of the fractures 610 is oriented along an x-y plane.
  • each of the fractures 620 is oriented along a z-y plane.
  • each of the x-y fractures 610 is intersected at substantially a right angle by a single corresponding z-y fracture 620.
  • a plurality of pairs 650 A is provided for the fracture network 600 A.
  • the concept of intersecting fractures shown in the fracture network 600A is but one of many possible arrangements.
  • Figure 6B presents an alternate but related arrangement for a fracture network 600B.
  • two z-y fractures 620 are provided with each of the x-y fractures 610.
  • Such groupings are shown at 650B.
  • the reservoir engineer may complete a plurality of horizontal wells in a subsurface formation.
  • some wells are completed along an x-axis within the formation, while other wells are completed along a z-axis in the formation.
  • the purpose is to provide substantial coverage of a field with a fracture network.
  • a fracturing fluid is injected into a first set of wells, such as the horizontal wells completed along the x-axis, in order to create fractures in the formation in a first vertical orientation. This may be done in accordance with the steps shown, for example, in Figures 2 A through 2C. Subsequently, steps are taken to change the orientation of the minimum principal stress in the formation. This may be done in accordance with the step shown, for example, in Figure 2E. Thereafter, a fracturing fluid is injected into a second set of wells, such as the horizontal wells completed along the z-axis, in order to create fractures in the formation in a second vertical orientation along the x-y plane. In the arrangements of Figures 6A and 6B, the second vertical orientation is at substantially a 90-degree angle to the first vertical orientation.
  • Figure 7 provides a plan view of a hydrocarbon development area 700, in one embodiment.
  • the hydrocarbon development area 700 has a surface 710.
  • the hydrocarbon development area 700 also has a subsurface 720.
  • the subsurface 720 includes a formation 725 containing hydrocarbon fluids.
  • the formation 725 comprises a rock matrix having low permeability.
  • the formation 725 may have, for example, a permeability less than about 10 millidarcies.
  • the wellbores for the first set of wells are shown at 732. These wellbores 732 extend along an x-axis. Thereafter, the subsurface formation 725 is fractured from perforations in the wellbores 732 for the first set of wells. Fractures are seen at 740. Hydrocarbon fluids are then produced from through the fractures 740 and the corresponding wellbores 732.
  • the in situ stress field within the subsurface formation 725 is changed. This may be as a natural result of the fluid production process. Alternatively, this may be as a result of selective injection of water or other fluids into the subsurface formation 725 in order to increase in situ pressure. In any instance, a second set of wells having wellbores 734 is also formed. These wellbores are also completed horizontally, and are oriented along a z-axis. [0252] After the in situ stress field within the subsurface formation 725 is changed, the subsurface formation 725 is fractured from perforations in the wellbores 734 for the second set of wells. Illustrative fractures from the wellbores 734 are seen at 750.
  • Hydrocarbon fluids are then produced from through the fractures 750 and the corresponding wellbores 734.
  • the wellbores 732 along the x-axis and the wellbores 734 along the z-axis cross. They do not intersect, but they do cross. This allows the respective fractures 740, 750 to intersect.
  • the intersecting fractures 740, 750 create a fracture network analogous to the fracture networks 650 A, 650B shown in Figures 6 A and 6B.
  • Figure 8 is a flow chart showing steps for performing a method 700 for creating a network of fractures in a reservoir, in one embodiment.
  • the reservoir preferably represents a rock matrix having a low permeability.
  • the permeability may be less than 10 millidarcies.
  • the reservoir may be a hydrocarbon-producing reservoir.
  • the reservoir may contain methane and other hydrocarbon gases.
  • the reservoir may be a tight-gas formation, a shale gas formation, or a coal bed methane formation.
  • the reservoir may also include so-called acid gases, such as carbon dioxide and hydrogen sulfide.
  • the reservoir may also incidentally contain water or brine.
  • the reservoir may be a geothermal zone containing water and, possibly, minerals. In this instance, the reservoir will produce steam.
  • the method 800 generally includes designing a desired fracture network. This is shown at Box 810.
  • the fracture network may be, for example, in accordance with the illustrative fracture networks 650 A, 650B shown and discussed in Figures 6 A and 6B.
  • the step of designing a desired fracture network of Box 810 is done using geomechanical simulation, which involves use of a software program and a processor.
  • the method 800 also includes determining required in situ stresses to create the fracture network within the reservoir. This is provided at Box 820. Determining required in situ stresses may be done in several ways. For example, downhole pressure measurements may be taken from existing wells. Such measurements are indicative of pore pressure acting within a rock matrix. Alternatively or in addition, micro-seismic testing may be conducted. Alternatively or in addition, tiltmeter readings may be monitored.
  • downhole stress modeling may be conducted.
  • ABAQUSTM software may be used to develop in situ stresses and resulting fractures.
  • the rock matrix making up the reservoir is initialized with certain mechanical properties.
  • Such properties may be, for example, elastic moduli and Poisson ratios.
  • Elastic moduli and Poisson ratios may be estimated based on interpreted lithologies for the rocks included in the model.
  • a stress field may be demonstrated by x, y, and z coordinates.
  • the in situ stress field will be affected in one of the horizontal directions due to tectonic forces acting from the Rocky Mountain range to the east. From the stress field modeling, the direction of least principal stress is determined. For formations deeper than about 1,000 feet, the direction of least principal stress will likely be in the "x" or "z” directions, where the x and z directions are horizontal and "y" is the vertical direction, such that hydraulically-induced fractures will be oriented in plane perpendicular to the "x" or "z” direction. [0261] The method 800 further includes designing a layout of wells to alter the in situ stresses. This is provided at Box 830.
  • Designing such a layout of wells means that wells are completed in the subsurface for the production and/or injection of fluids for the purpose of altering the in situ stress field.
  • the layout of wells may be, for example, in accordance with the layout of wellbores 732 and 734 of Figure 7.
  • the method 800 also includes injecting a fracturing fluid under pressure into the reservoir.
  • the purpose is to create an initial set of fractures. This is shown at Box 840.
  • the fractures will likely extend in a vertical plane through the formation, as shown in Figure 2C. The result is that the fractures do not interconnect and provide limited exposure of the wellbores to the formation.
  • FIG. 850 a next step is taken to monitor the in situ stresses in the reservoir. This is seen at Box 850. Monitoring the in situ stresses in the reservoir may be done in several ways. These are generally shown in the flow chart of Figure 9.
  • Figure 9 is a flow chart showing illustrative steps that may be taken for monitoring in situ stress fields.
  • monitoring may include conducting downhole pressure measurements. This is seen at Box 910.
  • monitoring may include micro-seismic and/or tiltmeter monitoring.
  • Monitoring may include taking readings from tiltmeters on a surface above the reservoir. This is shown at Box 930.
  • monitoring may include performing downhole stress modeling. This is seen at Box 940. Of course, combinations of any of these techniques may be employed.
  • the method 800 additionally includes updating the geomechanical simulation based on the monitored in situ stresses. This is indicated at Box 855. Further, the method 800 includes designing a program of modifying the in situ stress within the stress field. This is seen at Box 860. The step of designing a program of Box 860 is also done using geomechanical simulation.
  • the geomechanical simulations may be performed using commercially available software capable of capturing the complex interplay between the in situ stress state and the engineering practices. Examples of such software include finite element software (e.g. Abaqus or ELFEN); and discrete element software (e.g. PFC3D or ELFEN).
  • the geomechanical simulations incorporate fully-coupled constitutive relations that enable mathematical representations of in situ stress state and pore pressure, rock mechanical properties, engineering stimulation practices at the wellbores, and field production. Newly acquired data is input into the geomechanical simulations to foster iteration between history matching and predictive modes.
  • the method 800 also includes modifying the in situ stresses in the reservoir.
  • the in situ stresses may be modified through reservoir depletion over time.
  • the step 860 will comprise producing hydrocarbon fluids from the reservoir.
  • the step 865 may comprise injecting a fluid into the reservoir. The fluid is injected at a pressure lower than the parting pressure of the rock matrix. The fluid may be injected into each of a plurality of wells either (i) simultaneously, or (ii) in stages such that fluid is injected into one or more wells or one or more zones sequentially.
  • modifying the in situ stresses further comprises (i) specifying a length of time for injecting for selected wells, (ii) specifying a viscosity of fluid for injection into selected wells, (iii) modifying a temperature of the reservoir, or (iv) combinations thereof.
  • Modifying a temperature of the reservoir may comprise (i) injecting a heated gas into the reservoir, (ii) applying resistive heat to a rock matrix comprising the reservoir, (iii) actuating one or more downhole combustion burners, (iii) injecting a cooler fluid into the reservoir or (v) combinations thereof.
  • Modifying the in situ stresses may also comprise establishing assistive fracture paths.
  • the assistive fracture paths are in addition to the initial fractures created in step 840.
  • Establishing the assistive fracture paths may be done by creating a plurality of radially offset perforations into the reservoir through a plurality of wells. The orientation of the perforations may also be adjusted so that the perforations do not extend transverse to the wellbores.
  • establishing the assistive fracture paths may be done by injecting an acidic fluid through a plurality of wells to create worm holes in the reservoir.
  • the method 800 further includes injecting a fluid under pressure into the reservoir in order to expand upon the initial set of fractures and to create the network of fractures. This is shown at Box 870. Injecting a fluid into the reservoir to create the network of fractures may be done by determining pump rates and associated shear rates for selected wells.
  • At least two of the wells in the layout of wells are completed for the production of hydrocarbon fluids.
  • the network of fractures is designed to optimize production of the hydrocarbon fluids.
  • Injecting a fluid into the reservoir under pressure in accordance with the steps of Boxes 840 and 870 may comprise injecting the fluid through wells that have been completed principally for the production of hydrocarbon fluids.
  • injecting a fluid under pressure into the reservoir in accordance with the steps of Boxes 840 and 870 may further comprise injecting the fluid through selected wells that are completed for the injection of fluids.
  • the fluids being injected may represent an aqueous fluid such as brine.
  • At least two of the wells in the layout of wells are completed for the production of geothermally-produced steam.
  • the network of fractures is designed to optimize heat transfer for geothermal applications.
  • injecting a fluid under pressure into the reservoir in accordance with the steps of Boxes 840 and 870 may comprise injecting the fluid through selected wells completed for the production of the geothermally-produced steam.
  • at least two of the wells in the layout of wells are completed for the injection of acid gases.
  • injecting a fluid under pressure into the reservoir in accordance with the steps of Boxes 840 and 870 comprises injecting the fluid through selected wells completed for the injection of acid gases.
  • the acid gases may primarily comprise carbon dioxide.
  • the carbon dioxide may be injected as part of an enhanced oil recovery project. Alternatively, the carbon dioxide may be injected as part of a sequestration operation.
  • the network of fractures is designed to optimize C0 2 storage capacity.
  • injecting a fluid under pressure into the reservoir in accordance with the steps of Boxes 840 and 870 comprises injecting the drill cutting through selected wells for injection into the reservoir.
  • the reservoir comprises two or more zones.
  • the network of fractures is created within at least two different zones. Designing a desired fracture network system then involves designing a fracture network system in each of the at least two zones.
  • injecting a fluid under pressure into the reservoir involves injecting a fluid into each of the at least two zones so as to create the network of fractures within the at least two zones.
  • the network of fractures may be created in the manner described above in connection with Figures 3A-3B and/or Figures 5A-5C.
  • a plurality of wells within the layout of wells has already been perforated into the reservoir. Further, the reservoir has undergone hydrocarbon production for a period of time. In this instance, injecting a fluid under pressure into the reservoir in order to create the network of fractures involves re-fracturing each of the plurality of wells.
  • a desired fracture network system is first designed for draining the reservoir.
  • the in situ stresses needed to create the fracture network system are then determined.
  • a comprehensive system consisting of well / pad layout and well architecture is designed to alter the stress field around the individual wells.
  • a customized network of fractures is then created.
  • the methods disclosed herein are particularly beneficial for the development of unconventional reservoirs such as tight gas, shale gas, and coal bed methane, and the recovery of gas.
  • the methods are also beneficial for the sequestration of C0 2 .
  • the present methods will help to increase contact area from the wellbore to the reservoir.
  • the methods can be used to control fracture geometry and orientation.

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Abstract

L'invention porte sur un procédé de création d'un réseau de fractures dans un réservoir. Le procédé consiste à concevoir le système de réseau de fractures voulu, et à déterminer les contraintes in situ nécessaires pour créer le réseau de fractures voulu dans le réservoir. Le procédé consiste en outre à concevoir une disposition de puits afin de modifier les contraintes in situ dans le champ de contraintes, puis à injecter un fluide de fracturation sous pression dans le réservoir, afin de créer un ensemble initial de fractures dans le réservoir. Le procédé consiste également à surveiller les contraintes in situ dans le champ de contraintes, et à modifier les contraintes in situ dans le champ de contraintes. Le procédé consiste ensuite à injecter un fluide de fracturation sous pression dans le réservoir, de façon à étendre l'ensemble initial de fractures et à créer le réseau de fractures. L'invention porte également sur un procédé de production d'hydrocarbures à partir d'une formation souterraine, un réseau de fractures étant créé dans la production d'un seul puits dévié.
PCT/US2011/049579 2010-10-20 2011-08-29 Procédés d'établissement de réseau de fractures souterrain WO2012054139A2 (fr)

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DE112011103548T DE112011103548T5 (de) 2010-10-20 2011-08-29 Verfahren zum Erzeugen eines Untergrund-Rissnetzwerks
US13/825,796 US20130220604A1 (en) 2010-10-20 2011-08-29 Methods For Establishing A Subsurface Fracture Network
CA2814750A CA2814750A1 (fr) 2010-10-20 2011-08-29 Procedes d'etablissement de reseau de fractures souterrain
AU2011318546A AU2011318546A1 (en) 2010-10-20 2011-08-29 Methods for establishing a subsurface fracture network

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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014028432A1 (fr) * 2012-08-13 2014-02-20 Schlumberger Canada Limited Compétition entre des fractures hydrauliques transversales et axiales dans un puits horizontal
WO2014053043A1 (fr) * 2012-10-04 2014-04-10 Nexen Energy Ulc Procédé amélioré de fracturation hydraulique pour forages déviés
WO2014147226A2 (fr) * 2013-03-21 2014-09-25 Statoil Petroleum As Augmentation de la récupération des hydrocarbures dans des réservoirs
WO2014163853A2 (fr) * 2013-03-13 2014-10-09 Exxonmobil Upstream Research Company Production d'hydrocarbures à partir d'une formation
US20150007996A1 (en) * 2013-07-04 2015-01-08 IOR Canada Ltd. Method for Producing Oil From Induced Fractures Using a Single Wellbore and Multiple-Channel Tubing
US20150075784A1 (en) * 2013-09-19 2015-03-19 Shell Oil Company Phased stimulation methods
WO2016198894A3 (fr) * 2015-06-10 2017-01-19 Ikon Science Innovation Limited Procédé et appareil pour l'analyse de réservoirs et conception de fracture dans une couche de roche

Families Citing this family (27)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9784085B2 (en) * 2012-09-10 2017-10-10 Schlumberger Technology Corporation Method for transverse fracturing of a subterranean formation
US9719338B2 (en) * 2013-09-05 2017-08-01 Halliburton Energy Services, Inc. Determining fracturing rheological behavior of fracturing fluids
US10221667B2 (en) 2013-12-13 2019-03-05 Schlumberger Technology Corporation Laser cutting with convex deflector
WO2015089458A1 (fr) 2013-12-13 2015-06-18 Schlumberger Canada Limited Création de fentes radiales dans un puits de forage
US9617839B2 (en) 2014-05-28 2017-04-11 Exxonmobil Upstream Research Company Method of forming directionally controlled wormholes in a subterranean formation
US10001613B2 (en) * 2014-07-22 2018-06-19 Schlumberger Technology Corporation Methods and cables for use in fracturing zones in a well
US10738577B2 (en) 2014-07-22 2020-08-11 Schlumberger Technology Corporation Methods and cables for use in fracturing zones in a well
WO2016069977A1 (fr) 2014-10-30 2016-05-06 Schlumberger Canada Limited Création de fentes radiales dans une formation souterraine
US20160290112A1 (en) * 2015-04-02 2016-10-06 Nexen Energy Ulc Processes for hydraulic fracturing
US10344204B2 (en) 2015-04-09 2019-07-09 Diversion Technologies, LLC Gas diverter for well and reservoir stimulation
US10012064B2 (en) * 2015-04-09 2018-07-03 Highlands Natural Resources, Plc Gas diverter for well and reservoir stimulation
US20160326853A1 (en) * 2015-05-08 2016-11-10 Schlumberger Technology Corporation Multiple wellbore perforation and stimulation
US10364672B2 (en) 2016-03-28 2019-07-30 Baker Hughes, A Ge Company, Llc Completion optimization process based on acoustic logging data in the lateral section in a horizontal well
US10982520B2 (en) 2016-04-27 2021-04-20 Highland Natural Resources, PLC Gas diverter for well and reservoir stimulation
US12104828B2 (en) * 2017-03-24 2024-10-01 The Johns Hopkins University Coiled tubing for radiator enhanced geothermal system
CN107228656B (zh) * 2017-07-19 2023-05-09 中国电建集团中南勘测设计研究院有限公司 用于监测裂缝三向变形的组件及监测方法
US20190249527A1 (en) * 2018-02-09 2019-08-15 Crestone Peak Resources Simultaneous Fracturing Process
CN112012709B (zh) * 2019-05-30 2022-11-04 新奥科技发展有限公司 一种地热生产井及地热层多级压裂方法
US10934825B2 (en) * 2019-06-28 2021-03-02 Halliburton Energy Services, Inc. Pressurizing and protecting a parent well during fracturing of a child well
CN113027404B (zh) * 2019-12-09 2022-10-04 中国石油天然气股份有限公司 一种径向多分支井诱导裂缝定向压裂方法
CA3168841A1 (fr) 2020-01-24 2021-07-29 Xuebing FU Procedes de production de petrole de reservoir etanche par recuperation secondaire
CN113586020A (zh) * 2020-04-30 2021-11-02 中国石油化工股份有限公司 径向井结合二氧化碳压裂的直井体积压裂方法及系统
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CN114086935B (zh) * 2020-08-05 2024-05-07 中国石油化工股份有限公司 地热系统热储压裂缝网设计方法、装置以及存储介质
CN115142828A (zh) * 2021-03-31 2022-10-04 中国石油化工股份有限公司 水平井分段压裂模拟井筒、其实验装置及实验方法
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CN114278257B (zh) * 2021-12-24 2023-12-15 中海石油(中国)有限公司 海上油田开采与超临界二氧化碳封存的同步装置与方法

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3965993A (en) * 1974-09-20 1976-06-29 Schlumberger Technology Corporation Well bore perforating apparatus
US5884715A (en) * 1997-08-01 1999-03-23 Reddoch; Jeffrey Method and apparatus for injecting drilling waste into a well while drilling
US6318469B1 (en) * 1999-02-09 2001-11-20 Schlumberger Technology Corp. Completion equipment having a plurality of fluid paths for use in a well
US20070272407A1 (en) * 2006-05-25 2007-11-29 Halliburton Energy Services, Inc. Method and system for development of naturally fractured formations
US20080083531A1 (en) * 2006-10-10 2008-04-10 Halliburton Energy Services, Inc. Methods and systems for well stimulation using multiple angled fracturing
US20080087420A1 (en) * 2006-10-13 2008-04-17 Kaminsky Robert D Optimized well spacing for in situ shale oil development
US20090260828A1 (en) * 2008-04-16 2009-10-22 Gregory Kubala Use of Carbon-Dioxide-Based Fracturing Fluids
US7784545B2 (en) * 2004-05-14 2010-08-31 Maguire James Q In-situ method of fracturing gas shale and geothermal areas

Family Cites Families (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4724905A (en) 1986-09-15 1988-02-16 Mobil Oil Corporation Sequential hydraulic fracturing
US4830106A (en) 1987-12-29 1989-05-16 Mobil Oil Corporation Simultaneous hydraulic fracturing
US5111881A (en) 1990-09-07 1992-05-12 Halliburton Company Method to control fracture orientation in underground formation
US7946340B2 (en) 2005-12-01 2011-05-24 Halliburton Energy Services, Inc. Method and apparatus for orchestration of fracture placement from a centralized well fluid treatment center
US7931082B2 (en) 2007-10-16 2011-04-26 Halliburton Energy Services Inc., Method and system for centralized well treatment
US20100132946A1 (en) * 2008-12-01 2010-06-03 Matthew Robert George Bell Method for the Enhancement of Injection Activities and Stimulation of Oil and Gas Production
US8631872B2 (en) * 2009-09-24 2014-01-21 Halliburton Energy Services, Inc. Complex fracturing using a straddle packer in a horizontal wellbore

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3965993A (en) * 1974-09-20 1976-06-29 Schlumberger Technology Corporation Well bore perforating apparatus
US5884715A (en) * 1997-08-01 1999-03-23 Reddoch; Jeffrey Method and apparatus for injecting drilling waste into a well while drilling
US6318469B1 (en) * 1999-02-09 2001-11-20 Schlumberger Technology Corp. Completion equipment having a plurality of fluid paths for use in a well
US7784545B2 (en) * 2004-05-14 2010-08-31 Maguire James Q In-situ method of fracturing gas shale and geothermal areas
US20070272407A1 (en) * 2006-05-25 2007-11-29 Halliburton Energy Services, Inc. Method and system for development of naturally fractured formations
US20080083531A1 (en) * 2006-10-10 2008-04-10 Halliburton Energy Services, Inc. Methods and systems for well stimulation using multiple angled fracturing
US20080087420A1 (en) * 2006-10-13 2008-04-17 Kaminsky Robert D Optimized well spacing for in situ shale oil development
US20090260828A1 (en) * 2008-04-16 2009-10-22 Gregory Kubala Use of Carbon-Dioxide-Based Fracturing Fluids

Cited By (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014028432A1 (fr) * 2012-08-13 2014-02-20 Schlumberger Canada Limited Compétition entre des fractures hydrauliques transversales et axiales dans un puits horizontal
US10267131B2 (en) 2012-08-13 2019-04-23 Schlumberger Technology Corporation Competition between transverse and axial hydraulic fractures in horizontal well
CN104755699A (zh) * 2012-08-13 2015-07-01 普拉德研究及开发股份有限公司 水平井中的横向和轴向水力裂缝之间的竞争
WO2014053043A1 (fr) * 2012-10-04 2014-04-10 Nexen Energy Ulc Procédé amélioré de fracturation hydraulique pour forages déviés
GB2522145A (en) * 2012-10-04 2015-07-15 Nexen Energy Ulc Improved hydraulic fracturing process for deviated wellbores
CN105026684A (zh) * 2012-10-04 2015-11-04 尼克森能源无限责任公司 斜井筒的改进水力压裂方法
WO2014163853A2 (fr) * 2013-03-13 2014-10-09 Exxonmobil Upstream Research Company Production d'hydrocarbures à partir d'une formation
WO2014163853A3 (fr) * 2013-03-13 2015-04-02 Exxonmobil Upstream Research Company Production d'hydrocarbures à partir d'une formation
US20160047179A1 (en) * 2013-03-21 2016-02-18 Statoil Petroleum As Increasing hydrocarbon recovery from reservoirs
WO2014147226A2 (fr) * 2013-03-21 2014-09-25 Statoil Petroleum As Augmentation de la récupération des hydrocarbures dans des réservoirs
WO2014147226A3 (fr) * 2013-03-21 2014-12-24 Statoil Petroleum As Augmentation de la récupération des hydrocarbures dans des réservoirs
US10208547B2 (en) 2013-03-21 2019-02-19 Statoil Petroleum As Increasing hydrocarbon recovery from reservoirs
US20150007996A1 (en) * 2013-07-04 2015-01-08 IOR Canada Ltd. Method for Producing Oil From Induced Fractures Using a Single Wellbore and Multiple-Channel Tubing
CN105358792A (zh) * 2013-07-04 2016-02-24 Ior加拿大有限公司 使用单个井眼和多通道管道从诱导裂缝生产油的方法
US9976400B2 (en) * 2013-07-04 2018-05-22 IOR Canada Ltd. Method for producing oil from induced fractures using a single wellbore and multiple-channel tubing
US10024148B2 (en) 2013-07-04 2018-07-17 1OR Canada Ltd. Hydrocarbon recovery process exploiting multiple induced fractures
CN104453822A (zh) * 2013-09-19 2015-03-25 国际壳牌研究有限公司 对其中具有井筒的地下岩层分阶段激励的方法
US20150075784A1 (en) * 2013-09-19 2015-03-19 Shell Oil Company Phased stimulation methods
WO2016198894A3 (fr) * 2015-06-10 2017-01-19 Ikon Science Innovation Limited Procédé et appareil pour l'analyse de réservoirs et conception de fracture dans une couche de roche
US10851633B2 (en) 2015-06-10 2020-12-01 Ikon Science Innovation Limited Method and apparatus for reservoir analysis and fracture design in a rock layer

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DE112011103548T5 (de) 2013-08-08

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