CA1303972C - Limited entry, multiple fracturing from deviated wellbores - Google Patents
Limited entry, multiple fracturing from deviated wellboresInfo
- Publication number
- CA1303972C CA1303972C CA000550901A CA550901A CA1303972C CA 1303972 C CA1303972 C CA 1303972C CA 000550901 A CA000550901 A CA 000550901A CA 550901 A CA550901 A CA 550901A CA 1303972 C CA1303972 C CA 1303972C
- Authority
- CA
- Canada
- Prior art keywords
- holes
- wellbore
- formation
- fractures
- fracture
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 206010017076 Fracture Diseases 0.000 claims abstract description 88
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 50
- 239000012530 fluid Substances 0.000 claims abstract description 36
- 238000000034 method Methods 0.000 claims abstract description 35
- 238000011084 recovery Methods 0.000 claims abstract description 14
- 230000001939 inductive effect Effects 0.000 claims abstract description 5
- 208000006670 Multiple fractures Diseases 0.000 claims abstract description 4
- 208000010392 Bone Fractures Diseases 0.000 claims description 45
- 238000005086 pumping Methods 0.000 claims description 13
- 238000011282 treatment Methods 0.000 claims description 12
- 239000003245 coal Substances 0.000 claims description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 10
- 239000002253 acid Substances 0.000 claims description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 239000010949 copper Substances 0.000 claims description 4
- 238000005553 drilling Methods 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 3
- 229910052770 Uranium Inorganic materials 0.000 claims description 2
- 239000004058 oil shale Substances 0.000 claims description 2
- 230000000149 penetrating effect Effects 0.000 claims description 2
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 claims description 2
- 230000001965 increasing effect Effects 0.000 abstract description 5
- 230000000638 stimulation Effects 0.000 abstract description 3
- 238000010795 Steam Flooding Methods 0.000 abstract 1
- 239000002904 solvent Substances 0.000 abstract 1
- 239000004094 surface-active agent Substances 0.000 abstract 1
- 238000005755 formation reaction Methods 0.000 description 43
- 238000002347 injection Methods 0.000 description 6
- 239000007924 injection Substances 0.000 description 6
- 230000035699 permeability Effects 0.000 description 6
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 description 5
- 238000002485 combustion reaction Methods 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000005516 engineering process Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 238000011065 in-situ storage Methods 0.000 description 3
- XQCFHQBGMWUEMY-ZPUQHVIOSA-N Nitrovin Chemical compound C=1C=C([N+]([O-])=O)OC=1\C=C\C(=NNC(=N)N)\C=C\C1=CC=C([N+]([O-])=O)O1 XQCFHQBGMWUEMY-ZPUQHVIOSA-N 0.000 description 2
- 150000007513 acids Chemical class 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 239000000499 gel Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- BMZGSMUCRXYUGB-UHFFFAOYSA-N 5-chloro-2-methylaniline;hydron;chloride Chemical compound Cl.CC1=CC=C(Cl)C=C1N BMZGSMUCRXYUGB-UHFFFAOYSA-N 0.000 description 1
- 241000722951 Annona Species 0.000 description 1
- 235000007755 Annona Nutrition 0.000 description 1
- 235000011518 Annona purpurea Nutrition 0.000 description 1
- 241000592817 Caddo Species 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 235000008331 Pinus X rigitaeda Nutrition 0.000 description 1
- 235000011613 Pinus brutia Nutrition 0.000 description 1
- 241000018646 Pinus brutia Species 0.000 description 1
- 230000003466 anti-cipated effect Effects 0.000 description 1
- 230000001186 cumulative effect Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 239000002002 slurry Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
- 238000004441 surface measurement Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/27—Methods for stimulating production by forming crevices or fractures by use of eroding chemicals, e.g. acids
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B43/30—Specific pattern of wells, e.g. optimizing the spacing of wells
- E21B43/305—Specific pattern of wells, e.g. optimizing the spacing of wells comprising at least one inclined or horizontal well
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B7/00—Special methods or apparatus for drilling
- E21B7/04—Directional drilling
Abstract
LIMITED ENTRY METHOD FOR INDUCING SIMULTANEOUSLY
MULTIPLE FRACTURE IN DEVIATED WELLBORES
Abstract A hydraulic fracturing process for inducing simultaneously, multiple vertical fractures in a deviated wellbore located in a subterranean formation for the removal of resources therefrom, particularly hydrocarbonaceous fluids. The process results in increased recovery of hydrocarbonaceous fluids when combined with steam-flooding, solvent or surfactant stimulation processes. The wellbore is selectively perforated with holes sufficiently apart that multiple vertical fractures are produced. This occurs when the fracturing fluid rate through the limited holes causes a pressure drop across the holes sufficient to divert the fluid through essentially all of the holes.
MULTIPLE FRACTURE IN DEVIATED WELLBORES
Abstract A hydraulic fracturing process for inducing simultaneously, multiple vertical fractures in a deviated wellbore located in a subterranean formation for the removal of resources therefrom, particularly hydrocarbonaceous fluids. The process results in increased recovery of hydrocarbonaceous fluids when combined with steam-flooding, solvent or surfactant stimulation processes. The wellbore is selectively perforated with holes sufficiently apart that multiple vertical fractures are produced. This occurs when the fracturing fluid rate through the limited holes causes a pressure drop across the holes sufficient to divert the fluid through essentially all of the holes.
Description
~3~?39~7~
LIMITED ENTRY ~ETHOD FOR INDUCING SIMULTANEOUSLY
MULTIPLE FRACTURING IN DEVIATED WELLBORES
This invention is directed to the recovery of hydrocarbonaceous fluids from a low permeability formation via a deviated wellbore having multiple vertical fractures therein.
Desired fracture locations are selected along the wellbore. The wellbore is alternately perforated at the selected locations.
Subsequently, the perforations are hydraulically fractured in a manner to form simultaneously, multiple fractures.
Low permeability formations generally require significant stimulation to develop well productivity large enough to be of commercial value. Hydraulic fracturing, using proppant laden slurries and/or acid, is most commonly used in these stimulation applications. While individual well productivity usually is enough to generate profitable results, effective recovery of a significant percentage of the hydrocarbon in place is not assure~. For example, in the Annona Chalk formation of the Caddo Pine Island Field in northwestern Louisiana, hydraulic fracturing has been utilized as a part of the initial completion procedure in most wells. While this results in acceptable profitability for most wells, the proJected cumulative recovery for the field is only 15~ of -the original-oil-in-place (OOIP).
One method for increasing the percentage recovery is to reduce spacing between wells which, when considering that each well is fractùred, is tantamount to reducing the distance between fractures. Another method for decreasing the distance between fractures is described in U.S. Patent No. 3,835,928 issued to Strubhar et al. Disclosed therein is a method for drilling a deviated well~ore in a direction substantially normal to the preferred induced fracture orientation and then creating multiple vertical fractures from the deviated wellbore. This was Z
accomplished ~y selecting individual locations along the wellbore and alternately perforating and treating each set of perforations individually. The normal practice in deviated wellbores is to perforate with a high shot density to create a single, vertical fracture.
Therefore, what is needed is a method to create simultaneously, multiple vertical fractures in a deviated wellbore located in a subterranean formation or reservoir.
This invention is directed to a limited entry method for inducing simultaneous multiple vertical fractures in a deviated wellbore which penetrates a subterranean formation. The method comprises determining the distance the deviated wellbore must travel to obtain the most effective and efficient recovery of a desired material; drilling a deviated wellbore through a predetermined distance to obtain the most effective and efficient recovery of the desired material; placing a casing in the deviated wellbore;
ascertaining the number and size of perforations to be made in the casing for forming fractures at desired locations after deciding the fracture treatment fluid to be used, the fluid's pumping rate, and the perforation pressure drop necessary to divert the fluid through alI the holes, pumping conditions being applied to the treating fluid at a pressure and rate sufficient to create simultaneously multiple vertical fractures in the formation; perforating the wellbore to create holes therein of the ascertained number and size sufficient to create the fractures when a treating fluid is flowed therethrough at an ascertained pumping rate; and placing a pressure on the treating fluid in an amount and at a pumpirg rate sufficient to create simultaneously multiple vertical fractures in the formation through the holes.
The drawing is a schematic view of a deviated wellbore having simultaneously induced, multiple vertical fractures emanating from perforations therefrom where the wellbore is located in a formation from which it is desired to remove resources therefrom.
..;, .
' ' '' ~:;
~3~3S1~2 This invention is directed to a method for creating simultaneously, multiple vertical fractures from a deviated wellbore. It is often necessary to create multiple vertical fractures in a formation to recover desired resources therefrom.
This is necessary because often the formation is not as permeable as is desired. This invention, as disclosed below, can be utilized in many applications.
One such application is for facilitating the removal of ores from a formation containing same. Sareen et al. in U.S. Patent No. 3,896,879, disclose a method for increasing the permeability of a subterranean formation penetrated by at least one well which extends from the surface of the earth into the formation. This method comprises the injection of an aqueous hydrogen peroxide solution containing therein a stabilizing agent through the well into the subterranean formation. After injection, the solution diffuses into the fractures of the formation surroundina the well.
The stabilizing agent reacts with metal values in the formation which allows the hydrogen peroxide to decompose. The composition of hydrogen peroxide generates a gaseous medium causing additiona fracturing of the formation. Sareen et al. utilize a method for increasing the fracture size to obtain increased removal of copper ores from a formation. Utilization of the present invention will increase permeability by creating additional fractures.
In addition to removiny ores, particularly copper ores and iron ores from a formation, the present invention can be used to recover geothermal energy more efficiently ~y the creation of more fractures. ~ method for recovering geothermal energy is disclosed in U.S. Patent No. 3,863,709 which issued to Fitch on February 4, 197~. Disclosed in this patent is a method and system for recovering geothermal energy from a subterranean geothermal formation having a preferred vertical fracture orientatlon. At least two deviated wells are provided which extend into the geothermal formation in a direction transversely of the preferred vertical fracture orientation. ~ plurality of vertical fractures are hydraulically formed to intersect the devîated wells. A fluid is thereafter injected via one well into the fractures to absorb heat from the geothermal formation and the heated Fluid is recovered from the formation via another well.
The present invention can also be used to remove thermal energy produced during in situ combustion of coal by the creation of additional fractures. A method wherein thermal energy so produced by in situ combustion of coal is disclosed in U.S. Patent No.
4,019,577 which issued to Fitch et al. on April 26, 1977. Disclosed therein is a method for recovering thermal energy from a coal formation which has a preferred vertical fracture orientation. An injection well and a production well are provided to extend into the coal formation and a vertical fracture is formed by hydraulic fracturing techniques. These fractures are propagated into the coal formation to communicate with both the wells. The vertical fracture is propped in the lower portion only. Thereafter, a combustion-supporting gas is injected into the propped portion of the fracture and the coal is ignited. Injection of the combustion-supporting gas is continued to propagate a combustion zone along the propped portion of the fracture and hot production gases generated at the combustion zone are produced to recover the heat or thermal energy of the coal. Water may also be injected into the fracture to transport the heat resulting from the combustion of the coal to the production well for recovery theref`rom. Both the injection and production wells can be deviated wells which penetrate the coal formation in a direction transversely o~ the preferred fracture orientation.
Recovery of thermal energy from subterranean formations can also be used to generate steam. A method for such recovery is disclosed in U.S. Patent No. 4,015,663 which issued to Strubhar on April S, 1977.
In the practice of this invention, as shown in the drawing, a deviated wellbore 12 is placed into the pay zone of formation 10.
The wellbore 12 goes through formation 10 from which formation it is ~3g~3~
desired to remove a subterranean resource such as iron, copper ore, uranium ore! geothermal heat, coal, oil shale or hydrocarbonaceous fluids. A deviated well is drilled through formation 1~ in a direction sufficiently normal to the preferred fracture orientation which is perpendicular to the least principal in-situ horizontal stress into which it is desired to induce simultaneously, multiple vertical fractures.
Methods for determining the preferred fracture orientation are described by Slusser in U.S. Patent No. 3,547,198~ As taught therein, the preferred fracture orientation exists because of naturally occurring planes or weakness in the earth's formations.
It is known that the subterranean formations adjoin in a manner similar to surface rock. Therefore, surface measurements may be employed as a reasonably close indication of the preferred fracture orientation. The preferred fracture orientation may also be determined from measurements taken in wells penetrating a subterranean earth formation of interest. For example, impression packer surveys may be run throughout the area to determine the fracture orientation. Borehole Televiewer surveys offer a particularly good method of determining the preferred fracture trends. Borehole Televiewer surveys are discussed in an article by ~. Zemanek et al., entitled "The Borehole Televiewer -- A New Logging Concept for Fracture ~ocation and Other Types of 80rehole and Inspection," Journal of Petroleum Technology, Vol. XXI (June, 1969), pp. 762-774. Other methods for determining the preferred orientation are described in U.S. ~atent No. 3,285,335.
When the position of the fracture plane is determined, the direction of the slanted hole may be described either in terms of the angle it makes with the direction of maximum principal stress or in terms of the angle of incidence which the borehole makes with the fracture plane, the angle of incidence being the angle between the line of the slanted borehole and the line parallel to the fracture plane at the point of intersection of the borehole and the plane.
This angle can be any angle that allows traverse of the ~3~35~7Z
hydrocarbonaceous formation with a directional component normal to the preferred fracture orientation. To minimize the amount of hole drilled to permit the creation of several vertical fractures, this angle is from 10 to 90, preferably 30 or larger.
Another angle to consider is the angle of deviation from vertical of the wellbore as it passes through the formation of interest. This angle is critical to the amount of borehole exposed to the formation of interest from which multiple fractures can be simultaneously created. This angle should be lû to ~0. In the drawing, the angle of deviation is depicted as 70 from vertical as one example.
Wellbore 12 will have a casing therein. Wellbore 12 is deviated at least in the lower portion thereof such that it penetrates the subterranean formation 10 at an angle of at least 10 measured from the vertical and in an azimuth direction transversely to the preferred fracture orientation. If a casing is utili~ed, it is cemented into wellbore 12. Thereafter, the casing is selectively perforated in a manner so that in subseauent fracture treatments, fluids beino pumped therein will pass through all perforations at a substantial rate. Thus, limited perforations will be required and matched to the pump rate to achieve a pressure drop across the perforations resulting in diversion of fluid through all holes. The pumping rate should be at least one to 10 barrels per fracture where each fracture emanates from one or more holes so as to result in a pressure drop of 1380 kPa (200 psi) or more across the hole(s).
Borehole 12 is perforated to provide a plurality of perforations at preselected intervals therein. These perforations are spaced 3-to 3û meters (10 to lûû feet) apart so the desired fracture spacing can be obtained. Such perforations may at each level comprise two sets of perforations which are simultaneously formed on opposite sides of the borehole 12. A set can be one or more perforations.
Preferably, these perforations should have diameters between ~.4 mm and 12.7 mm (1/4 and 1/2 of an inch) and should be placed circumferentially about the casing in the anticipated plane of the ~3Q3~72 induced fracture. Other perforating techniques that will achieve limited entry conditions while permitting simultaneous creation of multiple, vertical fractures may be employed and will be apparent to those skilled in the art.
Perforations will be placed in borehole 12 in a manner such as to obtain the predetermined proper distance between fractures based upon reservoir characteristics. This determination is made in order to balance the effective reservoir drainage with the highest degree of profitability.
lo To create the desired simultaneous, multiple vertical fractures, wellbore 12 is perforated such that the horizontal distance between individual or clusters of perforations is equivalent to the preferred distance between fractures. The number and size of perforations are determined by the fracture treatment pumping rate and the pressure drop neoessary to divert fluid through all holes.
Qeferring to the drawina, the distance between vertical fractures i6 determined to be 6 meter~ (20 faet). ~he formation thiaknese 1~ 30 meters (100 feet). The horizontal distanoe the deviated wellbore 12 w~ll travel 1~ determlned to b~ 91 meters(30o feet). ~ wellbore is drilled into the pay zone of formation 10 which is approximately 70 from vertical, permitting approximately 16 fractures to be induced from the wellbore intersecting formation 10. Assuming that a pumping rate of 795 liters/minute (five barrels per minute9 BPM) per fracture is a minimum rate suitable to achieve adequate fracture growth, the total pump rate for the 16 fractures would be 12720 liters/minute (80 BPM~. By utilizing 12.7 mm (0.5 inch) perforations, two perforations per fracture (a total of 32 holes) would result in a 1793 kPa (260 psi) pressure drcp across perforations according to Figure 7-1~, page 104, SPE Monograph 1 by G. C. Howard and C. R. Fast This pressure drop is sufficient to successfully divert fracturing fluid through all perforations. Upon application of the determined pressure at the determined rate through the perforations, simultaneous, multiple vertical ~ractures are produced in formation 10.
. ' .
.
~3Q3~7~
....
Fracturing fluids which can be utilized include simple Newto,nian fluids, gels described as Power Law fluids, and acids.
Use of acids for a fracturing fluid is discussed in U~S. Patent No.
4,249,609 issued to Haafkens et al. on February 10, 1981.
Usq of a gel as a fracturing fluid is disclosed in U.S.
Patent No. 4,415,035 i~sued to Medlin et al. on November 15, 1983.
In a preferred mode of operation? perforations 14 as shown in the drawing can be treated, or "broken down" prior to pumping the main fracture treatment. A suitable "breakdown" treatment can consist of pumping an acid such as hydrochloric acid of a concentration of 7. 5 vol. % at 3180 llter~/minute (20 ~PM). B~ll sealers can be included in the acid to plug off perforations 14 receiving the acid. This would allow other perforations to be lS opened.
Following the breakdown treatment~ the main ~racturing treatment would be pumped into wellbore 12 starting with a pre-pad or pad volume prior to pumping a fluid laden with proppant. Acid, such as hydrochloric acid, could be used in place of a proppant laden fracturing fluid to achieve fracture conductivity by ~ormation etching in a carbonate reservoir. It can also be used as a means for substantially opening up perforations to accept fracturing fluids. The acid can also be used as a carrier for the proppant should a proppant be desired. Treatment volumes for utilization can be selected on the basis of the design specification to achieve the specific ~racture dimensions desired.
Use of this limited entry fracture treatment in a deviated wellbore can achieve close fracture spacing without drilling individual wells. It can also result in effective reservoir drainage even in very low permeability reservoirs.
Another application of this technology can be utili7ed in reservoirs that contain natural fractures upon which well productivity is highly dependent. This would result because the deviated wellbore itself can likely intersect more natural fractures ~L3g~3~
than a vertical well. Equally important, multiple induced vertical fractures would greatly increase the number of intersections with the natural fracture network. Spacing of the induced fractures can be selected on the basis of apparent distribution of the natural fractures.
Vertical simultaneous fractures induced in the deviated wellbore of the present invention would permit secondary and tertiary recovery techniques to be used effectively in low permeability reservoirs where use of current technology is impractical. Utilization of the present invention in combination with the injection of secondary and tertiary recovery fluids would result in the production of reservoir fluids from alternate pairs of fractures in an effective manner within practical time limits.
Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of this invention, as those skilled in the art would readily understand.
LIMITED ENTRY ~ETHOD FOR INDUCING SIMULTANEOUSLY
MULTIPLE FRACTURING IN DEVIATED WELLBORES
This invention is directed to the recovery of hydrocarbonaceous fluids from a low permeability formation via a deviated wellbore having multiple vertical fractures therein.
Desired fracture locations are selected along the wellbore. The wellbore is alternately perforated at the selected locations.
Subsequently, the perforations are hydraulically fractured in a manner to form simultaneously, multiple fractures.
Low permeability formations generally require significant stimulation to develop well productivity large enough to be of commercial value. Hydraulic fracturing, using proppant laden slurries and/or acid, is most commonly used in these stimulation applications. While individual well productivity usually is enough to generate profitable results, effective recovery of a significant percentage of the hydrocarbon in place is not assure~. For example, in the Annona Chalk formation of the Caddo Pine Island Field in northwestern Louisiana, hydraulic fracturing has been utilized as a part of the initial completion procedure in most wells. While this results in acceptable profitability for most wells, the proJected cumulative recovery for the field is only 15~ of -the original-oil-in-place (OOIP).
One method for increasing the percentage recovery is to reduce spacing between wells which, when considering that each well is fractùred, is tantamount to reducing the distance between fractures. Another method for decreasing the distance between fractures is described in U.S. Patent No. 3,835,928 issued to Strubhar et al. Disclosed therein is a method for drilling a deviated well~ore in a direction substantially normal to the preferred induced fracture orientation and then creating multiple vertical fractures from the deviated wellbore. This was Z
accomplished ~y selecting individual locations along the wellbore and alternately perforating and treating each set of perforations individually. The normal practice in deviated wellbores is to perforate with a high shot density to create a single, vertical fracture.
Therefore, what is needed is a method to create simultaneously, multiple vertical fractures in a deviated wellbore located in a subterranean formation or reservoir.
This invention is directed to a limited entry method for inducing simultaneous multiple vertical fractures in a deviated wellbore which penetrates a subterranean formation. The method comprises determining the distance the deviated wellbore must travel to obtain the most effective and efficient recovery of a desired material; drilling a deviated wellbore through a predetermined distance to obtain the most effective and efficient recovery of the desired material; placing a casing in the deviated wellbore;
ascertaining the number and size of perforations to be made in the casing for forming fractures at desired locations after deciding the fracture treatment fluid to be used, the fluid's pumping rate, and the perforation pressure drop necessary to divert the fluid through alI the holes, pumping conditions being applied to the treating fluid at a pressure and rate sufficient to create simultaneously multiple vertical fractures in the formation; perforating the wellbore to create holes therein of the ascertained number and size sufficient to create the fractures when a treating fluid is flowed therethrough at an ascertained pumping rate; and placing a pressure on the treating fluid in an amount and at a pumpirg rate sufficient to create simultaneously multiple vertical fractures in the formation through the holes.
The drawing is a schematic view of a deviated wellbore having simultaneously induced, multiple vertical fractures emanating from perforations therefrom where the wellbore is located in a formation from which it is desired to remove resources therefrom.
..;, .
' ' '' ~:;
~3~3S1~2 This invention is directed to a method for creating simultaneously, multiple vertical fractures from a deviated wellbore. It is often necessary to create multiple vertical fractures in a formation to recover desired resources therefrom.
This is necessary because often the formation is not as permeable as is desired. This invention, as disclosed below, can be utilized in many applications.
One such application is for facilitating the removal of ores from a formation containing same. Sareen et al. in U.S. Patent No. 3,896,879, disclose a method for increasing the permeability of a subterranean formation penetrated by at least one well which extends from the surface of the earth into the formation. This method comprises the injection of an aqueous hydrogen peroxide solution containing therein a stabilizing agent through the well into the subterranean formation. After injection, the solution diffuses into the fractures of the formation surroundina the well.
The stabilizing agent reacts with metal values in the formation which allows the hydrogen peroxide to decompose. The composition of hydrogen peroxide generates a gaseous medium causing additiona fracturing of the formation. Sareen et al. utilize a method for increasing the fracture size to obtain increased removal of copper ores from a formation. Utilization of the present invention will increase permeability by creating additional fractures.
In addition to removiny ores, particularly copper ores and iron ores from a formation, the present invention can be used to recover geothermal energy more efficiently ~y the creation of more fractures. ~ method for recovering geothermal energy is disclosed in U.S. Patent No. 3,863,709 which issued to Fitch on February 4, 197~. Disclosed in this patent is a method and system for recovering geothermal energy from a subterranean geothermal formation having a preferred vertical fracture orientatlon. At least two deviated wells are provided which extend into the geothermal formation in a direction transversely of the preferred vertical fracture orientation. ~ plurality of vertical fractures are hydraulically formed to intersect the devîated wells. A fluid is thereafter injected via one well into the fractures to absorb heat from the geothermal formation and the heated Fluid is recovered from the formation via another well.
The present invention can also be used to remove thermal energy produced during in situ combustion of coal by the creation of additional fractures. A method wherein thermal energy so produced by in situ combustion of coal is disclosed in U.S. Patent No.
4,019,577 which issued to Fitch et al. on April 26, 1977. Disclosed therein is a method for recovering thermal energy from a coal formation which has a preferred vertical fracture orientation. An injection well and a production well are provided to extend into the coal formation and a vertical fracture is formed by hydraulic fracturing techniques. These fractures are propagated into the coal formation to communicate with both the wells. The vertical fracture is propped in the lower portion only. Thereafter, a combustion-supporting gas is injected into the propped portion of the fracture and the coal is ignited. Injection of the combustion-supporting gas is continued to propagate a combustion zone along the propped portion of the fracture and hot production gases generated at the combustion zone are produced to recover the heat or thermal energy of the coal. Water may also be injected into the fracture to transport the heat resulting from the combustion of the coal to the production well for recovery theref`rom. Both the injection and production wells can be deviated wells which penetrate the coal formation in a direction transversely o~ the preferred fracture orientation.
Recovery of thermal energy from subterranean formations can also be used to generate steam. A method for such recovery is disclosed in U.S. Patent No. 4,015,663 which issued to Strubhar on April S, 1977.
In the practice of this invention, as shown in the drawing, a deviated wellbore 12 is placed into the pay zone of formation 10.
The wellbore 12 goes through formation 10 from which formation it is ~3g~3~
desired to remove a subterranean resource such as iron, copper ore, uranium ore! geothermal heat, coal, oil shale or hydrocarbonaceous fluids. A deviated well is drilled through formation 1~ in a direction sufficiently normal to the preferred fracture orientation which is perpendicular to the least principal in-situ horizontal stress into which it is desired to induce simultaneously, multiple vertical fractures.
Methods for determining the preferred fracture orientation are described by Slusser in U.S. Patent No. 3,547,198~ As taught therein, the preferred fracture orientation exists because of naturally occurring planes or weakness in the earth's formations.
It is known that the subterranean formations adjoin in a manner similar to surface rock. Therefore, surface measurements may be employed as a reasonably close indication of the preferred fracture orientation. The preferred fracture orientation may also be determined from measurements taken in wells penetrating a subterranean earth formation of interest. For example, impression packer surveys may be run throughout the area to determine the fracture orientation. Borehole Televiewer surveys offer a particularly good method of determining the preferred fracture trends. Borehole Televiewer surveys are discussed in an article by ~. Zemanek et al., entitled "The Borehole Televiewer -- A New Logging Concept for Fracture ~ocation and Other Types of 80rehole and Inspection," Journal of Petroleum Technology, Vol. XXI (June, 1969), pp. 762-774. Other methods for determining the preferred orientation are described in U.S. ~atent No. 3,285,335.
When the position of the fracture plane is determined, the direction of the slanted hole may be described either in terms of the angle it makes with the direction of maximum principal stress or in terms of the angle of incidence which the borehole makes with the fracture plane, the angle of incidence being the angle between the line of the slanted borehole and the line parallel to the fracture plane at the point of intersection of the borehole and the plane.
This angle can be any angle that allows traverse of the ~3~35~7Z
hydrocarbonaceous formation with a directional component normal to the preferred fracture orientation. To minimize the amount of hole drilled to permit the creation of several vertical fractures, this angle is from 10 to 90, preferably 30 or larger.
Another angle to consider is the angle of deviation from vertical of the wellbore as it passes through the formation of interest. This angle is critical to the amount of borehole exposed to the formation of interest from which multiple fractures can be simultaneously created. This angle should be lû to ~0. In the drawing, the angle of deviation is depicted as 70 from vertical as one example.
Wellbore 12 will have a casing therein. Wellbore 12 is deviated at least in the lower portion thereof such that it penetrates the subterranean formation 10 at an angle of at least 10 measured from the vertical and in an azimuth direction transversely to the preferred fracture orientation. If a casing is utili~ed, it is cemented into wellbore 12. Thereafter, the casing is selectively perforated in a manner so that in subseauent fracture treatments, fluids beino pumped therein will pass through all perforations at a substantial rate. Thus, limited perforations will be required and matched to the pump rate to achieve a pressure drop across the perforations resulting in diversion of fluid through all holes. The pumping rate should be at least one to 10 barrels per fracture where each fracture emanates from one or more holes so as to result in a pressure drop of 1380 kPa (200 psi) or more across the hole(s).
Borehole 12 is perforated to provide a plurality of perforations at preselected intervals therein. These perforations are spaced 3-to 3û meters (10 to lûû feet) apart so the desired fracture spacing can be obtained. Such perforations may at each level comprise two sets of perforations which are simultaneously formed on opposite sides of the borehole 12. A set can be one or more perforations.
Preferably, these perforations should have diameters between ~.4 mm and 12.7 mm (1/4 and 1/2 of an inch) and should be placed circumferentially about the casing in the anticipated plane of the ~3Q3~72 induced fracture. Other perforating techniques that will achieve limited entry conditions while permitting simultaneous creation of multiple, vertical fractures may be employed and will be apparent to those skilled in the art.
Perforations will be placed in borehole 12 in a manner such as to obtain the predetermined proper distance between fractures based upon reservoir characteristics. This determination is made in order to balance the effective reservoir drainage with the highest degree of profitability.
lo To create the desired simultaneous, multiple vertical fractures, wellbore 12 is perforated such that the horizontal distance between individual or clusters of perforations is equivalent to the preferred distance between fractures. The number and size of perforations are determined by the fracture treatment pumping rate and the pressure drop neoessary to divert fluid through all holes.
Qeferring to the drawina, the distance between vertical fractures i6 determined to be 6 meter~ (20 faet). ~he formation thiaknese 1~ 30 meters (100 feet). The horizontal distanoe the deviated wellbore 12 w~ll travel 1~ determlned to b~ 91 meters(30o feet). ~ wellbore is drilled into the pay zone of formation 10 which is approximately 70 from vertical, permitting approximately 16 fractures to be induced from the wellbore intersecting formation 10. Assuming that a pumping rate of 795 liters/minute (five barrels per minute9 BPM) per fracture is a minimum rate suitable to achieve adequate fracture growth, the total pump rate for the 16 fractures would be 12720 liters/minute (80 BPM~. By utilizing 12.7 mm (0.5 inch) perforations, two perforations per fracture (a total of 32 holes) would result in a 1793 kPa (260 psi) pressure drcp across perforations according to Figure 7-1~, page 104, SPE Monograph 1 by G. C. Howard and C. R. Fast This pressure drop is sufficient to successfully divert fracturing fluid through all perforations. Upon application of the determined pressure at the determined rate through the perforations, simultaneous, multiple vertical ~ractures are produced in formation 10.
. ' .
.
~3Q3~7~
....
Fracturing fluids which can be utilized include simple Newto,nian fluids, gels described as Power Law fluids, and acids.
Use of acids for a fracturing fluid is discussed in U~S. Patent No.
4,249,609 issued to Haafkens et al. on February 10, 1981.
Usq of a gel as a fracturing fluid is disclosed in U.S.
Patent No. 4,415,035 i~sued to Medlin et al. on November 15, 1983.
In a preferred mode of operation? perforations 14 as shown in the drawing can be treated, or "broken down" prior to pumping the main fracture treatment. A suitable "breakdown" treatment can consist of pumping an acid such as hydrochloric acid of a concentration of 7. 5 vol. % at 3180 llter~/minute (20 ~PM). B~ll sealers can be included in the acid to plug off perforations 14 receiving the acid. This would allow other perforations to be lS opened.
Following the breakdown treatment~ the main ~racturing treatment would be pumped into wellbore 12 starting with a pre-pad or pad volume prior to pumping a fluid laden with proppant. Acid, such as hydrochloric acid, could be used in place of a proppant laden fracturing fluid to achieve fracture conductivity by ~ormation etching in a carbonate reservoir. It can also be used as a means for substantially opening up perforations to accept fracturing fluids. The acid can also be used as a carrier for the proppant should a proppant be desired. Treatment volumes for utilization can be selected on the basis of the design specification to achieve the specific ~racture dimensions desired.
Use of this limited entry fracture treatment in a deviated wellbore can achieve close fracture spacing without drilling individual wells. It can also result in effective reservoir drainage even in very low permeability reservoirs.
Another application of this technology can be utili7ed in reservoirs that contain natural fractures upon which well productivity is highly dependent. This would result because the deviated wellbore itself can likely intersect more natural fractures ~L3g~3~
than a vertical well. Equally important, multiple induced vertical fractures would greatly increase the number of intersections with the natural fracture network. Spacing of the induced fractures can be selected on the basis of apparent distribution of the natural fractures.
Vertical simultaneous fractures induced in the deviated wellbore of the present invention would permit secondary and tertiary recovery techniques to be used effectively in low permeability reservoirs where use of current technology is impractical. Utilization of the present invention in combination with the injection of secondary and tertiary recovery fluids would result in the production of reservoir fluids from alternate pairs of fractures in an effective manner within practical time limits.
Although the present invention has been described with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of this invention, as those skilled in the art would readily understand.
Claims (9)
1. A limited entry method for inducing simultaneously multiple vertical fractures in a deviated wellbore penetrating a subterranean formation comprising:
(a) determining the horizontal distance the deviated wellbore must travel to obtain the most effective and efficient recovery of resources from the formation;
(b) drilling the deviated wellbore through the formation at an angle of deviation sufficient to achieve the horizontal distance and at an angle of incidence to a preferred fracture orientation sufficient to obtain the most effective and efficient recovery of the resources;
(c) casing the deviated wellbore;
(d) ascertaining the number and size of holes to be made in the wellbore casing after deciding a fracture treatment fluid to be used, the fluid's pumping rate, and the perforation pressure drop necessary to divert the fluid through all holes at a rate sufficient to simultaneously create multiple vertical fractures in the formation;
(e) perforating the wellbore to create holes therein of the ascertained number and size sufficient to create the fractures when flowing a treating fluid therethrough at an ascertained pumping rate; and (f) placing a pressure on the treating fluid in an amount and at a pumping rate sufficient to create simultaneously multiple vertical fractures in the formation through the holes.
(a) determining the horizontal distance the deviated wellbore must travel to obtain the most effective and efficient recovery of resources from the formation;
(b) drilling the deviated wellbore through the formation at an angle of deviation sufficient to achieve the horizontal distance and at an angle of incidence to a preferred fracture orientation sufficient to obtain the most effective and efficient recovery of the resources;
(c) casing the deviated wellbore;
(d) ascertaining the number and size of holes to be made in the wellbore casing after deciding a fracture treatment fluid to be used, the fluid's pumping rate, and the perforation pressure drop necessary to divert the fluid through all holes at a rate sufficient to simultaneously create multiple vertical fractures in the formation;
(e) perforating the wellbore to create holes therein of the ascertained number and size sufficient to create the fractures when flowing a treating fluid therethrough at an ascertained pumping rate; and (f) placing a pressure on the treating fluid in an amount and at a pumping rate sufficient to create simultaneously multiple vertical fractures in the formation through the holes.
2. The method as recited in claim 1 where in step (b) the angle of incidence is from 10° to 90°.
3. The method as recited in claim 1 where in step (b) the angle of deviation is from 10° to 90°.
4. The method as recited in claim 1 where in step (e) the fractures are 3m to 30 m apart and are derived from holes of a diameter of 6.35mm to 12.7mm along the wellbore.
5. The method as recited in claim 1 where in step (e) the pumping rate is at least 159 to 1590 liters per minute per fracture and where each fracture emanates from one or more holes which results in a pressure drop of 1380 kPa or more across the holes.
6. The method as recited in claim 1 where in step (d) the holes are treated prior to placing a main fracturing treatment fluid into the deviated wellbore and which treatment comprises a solution of 7.5 volume % hydrochloric acid that is pumped into the wellbore at a rate of 3180 liters per minute.
7. The method as recited in claim 1 where after step (e) and prior to creating the multiple fractures, hydrochloric acid is placed through the holes as a means for substantially opening up perforations to accept fracturing fluids.
8. The method as recited in claim 1 where after step (e) ball sealers are placed in a solution of 7.5 volume percent hydrochloric acid to close off those perforations which have previously received acid to allow other perforations to be opened.
9 The method as recited in claim 1 where the formation contains a subterranean resource such as iron, copper ore, uranium ore, geothermal heat, coal, oil shale, or hydrocarbonaceous fluids.
2009h/0150h
2009h/0150h
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US92946286A | 1986-11-12 | 1986-11-12 | |
| US929,462 | 1986-11-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1303972C true CA1303972C (en) | 1992-06-23 |
Family
ID=25457903
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000550901A Expired - Lifetime CA1303972C (en) | 1986-11-12 | 1987-11-03 | Limited entry, multiple fracturing from deviated wellbores |
Country Status (4)
| Country | Link |
|---|---|
| CA (1) | CA1303972C (en) |
| GB (1) | GB2197364B (en) |
| NL (1) | NL193388C (en) |
| NO (1) | NO176588C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8196661B2 (en) | 2007-01-29 | 2012-06-12 | Noetic Technologies Inc. | Method for providing a preferential specific injection distribution from a horizontal injection well |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10808497B2 (en) | 2011-05-11 | 2020-10-20 | Schlumberger Technology Corporation | Methods of zonal isolation and treatment diversion |
| US8905133B2 (en) | 2011-05-11 | 2014-12-09 | Schlumberger Technology Corporation | Methods of zonal isolation and treatment diversion |
| US10738577B2 (en) | 2014-07-22 | 2020-08-11 | Schlumberger Technology Corporation | Methods and cables for use in fracturing zones in a well |
| US10001613B2 (en) | 2014-07-22 | 2018-06-19 | Schlumberger Technology Corporation | Methods and cables for use in fracturing zones in a well |
| WO2017111640A1 (en) | 2015-12-21 | 2017-06-29 | Schlumberger Technology Corporation | Pre-processed fiber flocks and methods of use thereof |
| CN111648753B (en) * | 2020-05-11 | 2022-06-03 | 中国石油天然气股份有限公司 | Hydraulic fracturing crack distribution optimization method for newly drilled horizontal well in water injection development well network |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3835928A (en) * | 1973-08-20 | 1974-09-17 | Mobil Oil Corp | Method of creating a plurality of fractures from a deviated well |
| US4415035A (en) * | 1982-03-18 | 1983-11-15 | Mobil Oil Corporation | Method for fracturing a plurality of subterranean formations |
-
1987
- 1987-11-02 NL NL8702612A patent/NL193388C/en not_active IP Right Cessation
- 1987-11-03 CA CA000550901A patent/CA1303972C/en not_active Expired - Lifetime
- 1987-11-05 GB GB8726011A patent/GB2197364B/en not_active Expired - Lifetime
- 1987-11-11 NO NO874694A patent/NO176588C/en not_active IP Right Cessation
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8196661B2 (en) | 2007-01-29 | 2012-06-12 | Noetic Technologies Inc. | Method for providing a preferential specific injection distribution from a horizontal injection well |
Also Published As
| Publication number | Publication date |
|---|---|
| NO176588B (en) | 1995-01-16 |
| NO176588C (en) | 1995-04-26 |
| NL193388B (en) | 1999-04-01 |
| NO874694D0 (en) | 1987-11-11 |
| GB2197364B (en) | 1990-06-06 |
| NL193388C (en) | 1999-08-03 |
| NO874694L (en) | 1988-05-13 |
| GB8726011D0 (en) | 1987-12-09 |
| GB2197364A (en) | 1988-05-18 |
| NL8702612A (en) | 1988-06-01 |
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