WO2002063132A1 - Oil well perforator - Google Patents

Oil well perforator Download PDF

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Publication number
WO2002063132A1
WO2002063132A1 PCT/GB2002/000278 GB0200278W WO02063132A1 WO 2002063132 A1 WO2002063132 A1 WO 2002063132A1 GB 0200278 W GB0200278 W GB 0200278W WO 02063132 A1 WO02063132 A1 WO 02063132A1
Authority
WO
WIPO (PCT)
Prior art keywords
oil well
casing
perforators
substrate
perforator
Prior art date
Application number
PCT/GB2002/000278
Other languages
French (fr)
Inventor
Brian Bourne
Original Assignee
Qinetiq Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Qinetiq Limited filed Critical Qinetiq Limited
Publication of WO2002063132A1 publication Critical patent/WO2002063132A1/en

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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
    • E21B43/11—Perforators; Permeators
    • E21B43/116—Gun or shaped-charge perforators
    • 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
    • E21B29/00—Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground
    • E21B29/02—Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground by explosives or by thermal or chemical means
    • 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
    • E21B43/11—Perforators; Permeators

Definitions

  • This invention relates to the field of oil wells and in particular to the explosive and other devices that are used to perforate oil well casings and hydrocarbon bearing rocks in order to create channels through which oil and gas can flow into the well bore.
  • Oil well perforators generally perforate oil well casings in one of two ways. Deep hole perforators are designed to produce a high level of perforation through the metal casing and cement into the hydrocarbon bearing rocks. Big hole perforators are designed to produce large holes in the casing only.
  • a shaped charge consists of a cylindrical tubular casing containing a hollow metal liner, mounted so that its axis of symmetry is coincident with that of the casing.
  • the liner shape is most commonly conical although other geometries such as hemispheres or trumpets can be used.
  • the base of the liner is at the end of the cylinder facing the target and explosive is packed within the casing and around the outside of the liner. When the explosive is detonated at the end of the cylinder furthest from the target , a detonation front sweeps the liner causing it to collapse and produce a high velocity jet of liner material which is directed towards the target.
  • a history of shaped charge warheads can be found in Fundamentals of Shaped Charges by Walters WP andZukas JA (ISBN 0-471-62172-2 (1989)).
  • the hollow liners used in big hole perforators are generally parabolic in shape and are made of 60Cu/40Zn brass.
  • the apex of the liner has a hole in it which facilitates the formation of a large diameter jet (larger than if the liner surface continued all the way to the apex).
  • big hole perforators For typical pipe diameters (on the order of 100 mm), big hole perforators have a diameter of approximately 42 mm with a hole of diameter 10mm in the apex of the liner. This configuration is capable of producing a hole of approximately 20-25 mm in the oil well casing.
  • a drawback of shaped charge based perforators is that the geometry of the shaped charge is incapable of producing a hole greater than that of the diameter of the charge. Shaped charge based big hole perforators are therefore limited in the size of hole they can produce.
  • this invention provides an oil well perforator for producing holes in the casing of an oil well comprising a substrate, a linear cutting charge mounted upon the substrate, the cutting charge and substrate together being adapted for location within an oil well, and detonation means for detonating the cutting charge wherein the substrate and cutting charge are configured such that, in use, detonation of the cutting charge cuts a hole in the oil well casing.
  • the substrate should be any suitable means of supporting the charges in a manner that will not interfere with their operation.
  • the charges could be carried on a friable substrate which disintegrates upon detonation of the charges.
  • a conventional gun deployment system which is common in the oil and gas industries may be used. Such gun systems would be sufficiently robust to be withdrawn from the well bore after firing.
  • a further alternative would be a so-called "full flow gun system”. Such a gun system would be arranged to disintegrate upon firing in much the same way as the friable substrate mentioned above.
  • the substrate should be sufficiently friable such that following detonation of the cutting charge it disintegrates and the debris falls down the oil well pipe.
  • the substrate is made of a blown ceramic material.
  • Such materials are relatively light and are capable of easy machining thereby allowing complex shaped grooves to be created for support of the cutting charge/shaped charge(s).
  • Such materials are also sufficiently robust to be deployed down the pipe.
  • An example of a suitable ceramic material is AL 203 manufactured by Friatec DPL in France.
  • This invention utilises explosive cutting charges to cut the oil well casing.
  • Such charges can be flexible linear shaped charges comprising explosive which has been extruded together with a metal or plastic sheath (The cutting charge may be copper, silver or polymer lined).
  • the cutting charge may be copper, silver or polymer lined).
  • other versions of explosive cutting charges may be rigid and pre-formed into a preferred shape or configuration.
  • These cutting cords can be made into any size and can be configured into any shape required. In use these charges chop the well bore casing into pieces that do not subsequently interfere with down hole activities.
  • the gape of the cord (which is defined as the distance across the mouth of the linear charge) can be made into any size appropriate to the thickness of the metal to be cut.
  • the cords should be at a reasonably constant distance from the metal to be cut, preferably around one gape length.
  • the gape size may need to be increased.
  • the invention can be mounted on a reusable gun arrangement similar to existing systems.
  • a method of producing holes in the casing of an oil well comprising the steps of: i) placing an oil well perforator according to the present invention in an oil well at a location where it is desired to produce a hole; ii) detonating the oil well perforator.
  • Figure 1 shows the oil well and oil well perforator in cross section
  • Figure 2 shows the oil well casing and oil well perforator in cutaway.
  • Figure 1 shows an oil well that has been bored into hydrocarbon bearing rocks 1.
  • the oil well comprises a metal casing 3 which is surrounded by a concrete layer 5 which separates it from the rocks 1.
  • the oil well perforator (7, 9) comprises a friable substrate 7 and a cutting charge 9. (The detonator for the cutting charge is not shown).
  • Figure 2 shows a 3 -dimensional view of part of the metal pipe 3 depicted in Figure 1 (Note: like numerals are used to denote like features).
  • a window 11 has been cut away in the side of the pipe in order to show the configuration of the cutting charge 9 upon the substrate 7.
  • the configuration of the cutting charge 9 will be dependent upon the size of hole which it is desired to make in the metal casing 3. In this case the cutting charge has been formed into an approximation of a spoked wheel.
  • An alternative cutting charge arrangement is a ladder like formation.
  • a hole will be cut in the metal casing 3.
  • a hole similar to the cutaway window 11 will be formed. Debris from the casing 3 and the substrate 7 will fall down the well.
  • the detonation of the cutting charge 9 will be a complex procedure but it should be designed such that the cord element on the periphery of the wheel detonates substantially simultaneously.

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  • Geology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mining & Mineral Resources (AREA)
  • Environmental & Geological Engineering (AREA)
  • Fluid Mechanics (AREA)
  • Physics & Mathematics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Drilling And Exploitation, And Mining Machines And Methods (AREA)
  • Perforating, Stamping-Out Or Severing By Means Other Than Cutting (AREA)

Abstract

This invention relates to the field of oil wells and in particular to the explosive and other devices that are used to perforate oil well casings and hydrocarbon bearing rocks in other to create channels though which oil and gas can flow into the well bore. Existing oil well perforators are either termed 'big hole' perforators which are designed to produce large holes in the oil well casing only or 'deep hole' perforators which are designed to perforate the casing of the well into the surrounding rocks. This invention proposes a novel form of big hole perforator capable of producing larger holes than existing big hole perforators in the casing of an oil well.

Description

OIL WELL PERFORATOR
This invention relates to the field of oil wells and in particular to the explosive and other devices that are used to perforate oil well casings and hydrocarbon bearing rocks in order to create channels through which oil and gas can flow into the well bore.
The metal casing of an oil well bore is surrounded by cement which is in turn in contact with the hydrocarbon bearing rocks. Oil well perforators generally perforate oil well casings in one of two ways. Deep hole perforators are designed to produce a high level of perforation through the metal casing and cement into the hydrocarbon bearing rocks. Big hole perforators are designed to produce large holes in the casing only.
Existing perforators are deployed down the oil well casing by mounting them in a gun and hundreds may be used at any one time.
Both deep hole and big hole perforators use a form of shaped hollow charge. In its most common configuration a shaped charge consists of a cylindrical tubular casing containing a hollow metal liner, mounted so that its axis of symmetry is coincident with that of the casing. The liner shape is most commonly conical although other geometries such as hemispheres or trumpets can be used. The base of the liner is at the end of the cylinder facing the target and explosive is packed within the casing and around the outside of the liner. When the explosive is detonated at the end of the cylinder furthest from the target , a detonation front sweeps the liner causing it to collapse and produce a high velocity jet of liner material which is directed towards the target. A history of shaped charge warheads can be found in Fundamentals of Shaped Charges by Walters WP andZukas JA (ISBN 0-471-62172-2 (1989)).
The hollow liners used in big hole perforators are generally parabolic in shape and are made of 60Cu/40Zn brass. The apex of the liner has a hole in it which facilitates the formation of a large diameter jet (larger than if the liner surface continued all the way to the apex). For typical pipe diameters (on the order of 100 mm), big hole perforators have a diameter of approximately 42 mm with a hole of diameter 10mm in the apex of the liner. This configuration is capable of producing a hole of approximately 20-25 mm in the oil well casing.
A drawback of shaped charge based perforators is that the geometry of the shaped charge is incapable of producing a hole greater than that of the diameter of the charge. Shaped charge based big hole perforators are therefore limited in the size of hole they can produce.
Larger holes in the oil well casing are however desirable since they can increase the flow of gas and oil into the oil well. Currently larger holes are produced by lowering a cutting/milling device into the hole and removing a section of the oil well casing at a particular location. This is however time consuming (the desired location can be many kilometres underground) and costly.
It is therefore an object of the present invention to provide a big hole perforator which substantially overcomes or mitigates at least some of the problems with current big hole perforators.
Accordingly this invention provides an oil well perforator for producing holes in the casing of an oil well comprising a substrate, a linear cutting charge mounted upon the substrate, the cutting charge and substrate together being adapted for location within an oil well, and detonation means for detonating the cutting charge wherein the substrate and cutting charge are configured such that, in use, detonation of the cutting charge cuts a hole in the oil well casing.
The substrate should be any suitable means of supporting the charges in a manner that will not interfere with their operation. For example, the charges could be carried on a friable substrate which disintegrates upon detonation of the charges. Alternatively, a conventional gun deployment system which is common in the oil and gas industries may be used. Such gun systems would be sufficiently robust to be withdrawn from the well bore after firing. A further alternative would be a so-called "full flow gun system". Such a gun system would be arranged to disintegrate upon firing in much the same way as the friable substrate mentioned above.
In the case of a friable substrate, the substrate should be sufficiently friable such that following detonation of the cutting charge it disintegrates and the debris falls down the oil well pipe. Preferably therefore the substrate is made of a blown ceramic material. Such materials are relatively light and are capable of easy machining thereby allowing complex shaped grooves to be created for support of the cutting charge/shaped charge(s). Such materials are also sufficiently robust to be deployed down the pipe. An example of a suitable ceramic material is AL 203 manufactured by Friatec DPL in France.
This invention utilises explosive cutting charges to cut the oil well casing. Such charges can be flexible linear shaped charges comprising explosive which has been extruded together with a metal or plastic sheath (The cutting charge may be copper, silver or polymer lined). However, other versions of explosive cutting charges may be rigid and pre-formed into a preferred shape or configuration. These cutting cords can be made into any size and can be configured into any shape required. In use these charges chop the well bore casing into pieces that do not subsequently interfere with down hole activities.
The gape of the cord (which is defined as the distance across the mouth of the linear charge) can be made into any size appropriate to the thickness of the metal to be cut. The cords should be at a reasonably constant distance from the metal to be cut, preferably around one gape length.
If there is fluid between the cutting charge and the oil well casing then the gape size may need to be increased.
Conveniently the invention can be mounted on a reusable gun arrangement similar to existing systems. Correspondingly, there is provided a method of producing holes in the casing of an oil well comprising the steps of: i) placing an oil well perforator according to the present invention in an oil well at a location where it is desired to produce a hole; ii) detonating the oil well perforator.
An embodiment of the oil well perforator according to the present invention will now be described with reference to the accompanying drawings in which:
Figure 1 shows the oil well and oil well perforator in cross section, and Figure 2 shows the oil well casing and oil well perforator in cutaway.
Figure 1 shows an oil well that has been bored into hydrocarbon bearing rocks 1. The oil well comprises a metal casing 3 which is surrounded by a concrete layer 5 which separates it from the rocks 1.
The oil well perforator (7, 9) comprises a friable substrate 7 and a cutting charge 9. (The detonator for the cutting charge is not shown).
Figure 2 shows a 3 -dimensional view of part of the metal pipe 3 depicted in Figure 1 (Note: like numerals are used to denote like features). A window 11 has been cut away in the side of the pipe in order to show the configuration of the cutting charge 9 upon the substrate 7. The configuration of the cutting charge 9 will be dependent upon the size of hole which it is desired to make in the metal casing 3. In this case the cutting charge has been formed into an approximation of a spoked wheel. An alternative cutting charge arrangement is a ladder like formation.
Upon detonation of the cutting charge 9 by the detonator (not shown) a hole will be cut in the metal casing 3. For the configuration shown a hole similar to the cutaway window 11 will be formed. Debris from the casing 3 and the substrate 7 will fall down the well. The detonation of the cutting charge 9 will be a complex procedure but it should be designed such that the cord element on the periphery of the wheel detonates substantially simultaneously.
Other ways of configuring the cutting charge of the invention will be readily apparent to the skilled person.

Claims

1. An oil well perforator for producing holes in the casing of an oil well comprising a substrate, a linear cutting charge mounted upon the substrate, the cutting charge and substrate together being adapted for location within an oil well, and detonation means for detonating the cutting charge wherein the substrate and cutting charge are configured such that, in use, detonation of the cutting charge cuts a hole in the oil well casing.
2. An oil well perforator as claimed in Claim 1 wherein the substrate is friable.
3. An oil well perforator as claimed in Claim 2 wherein the friable substrate comprises a blown ceramic material.
4. An oil well perforator as claimed in Claim 1 wherein the cutting charge is arranged in use to be at a substantially constant distance from the casing of the oil well.
5. An oil well perforator as claimed in Claim 2 wherein the cutting charge is arranged in use to be at a distance of approximately one gape length from the metal casing.
6. A method of producing holes in the casing of an oil well comprising the steps of: iii) placing an oil well perforator according to any of Claims 1 to 4 in an oil well at a location where it is desired to produce a hole; iv) detonating the oil well perforator.
PCT/GB2002/000278 2001-02-06 2002-01-23 Oil well perforator WO2002063132A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB0102913A GB0102913D0 (en) 2001-02-06 2001-02-06 Oil well perforator
GB0102913.1 2001-02-06

Publications (1)

Publication Number Publication Date
WO2002063132A1 true WO2002063132A1 (en) 2002-08-15

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ID=9908195

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Application Number Title Priority Date Filing Date
PCT/GB2002/000278 WO2002063132A1 (en) 2001-02-06 2002-01-23 Oil well perforator

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WO (1) WO2002063132A1 (en)

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3627066A (en) * 1970-07-08 1971-12-14 Woodrow W Johnson Perforator for water and oil wells
US4502550A (en) * 1982-12-06 1985-03-05 Magnum Jet, Inc. Modular through-tubing casing gun
GB2175674A (en) * 1985-04-30 1986-12-03 Vetco Ltd C E An explosive cutting device
US5564499A (en) * 1995-04-07 1996-10-15 Willis; Roger B. Method and device for slotting well casing and scoring surrounding rock to facilitate hydraulic fractures
EP0846838A2 (en) * 1996-12-04 1998-06-10 Halliburton Energy Services, Inc. Methods and apparatus for performing explosive cutting operations in a subterranean well
US5797464A (en) * 1996-02-14 1998-08-25 Owen Oil Tools, Inc. System for producing high density, extra large well perforations
GB2342144A (en) * 1998-09-30 2000-04-05 Western Atlas Int Inc Shaped charges
GB2346633A (en) * 1999-01-15 2000-08-16 Baker Hughes Inc Window forming by flame cutting

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3627066A (en) * 1970-07-08 1971-12-14 Woodrow W Johnson Perforator for water and oil wells
US4502550A (en) * 1982-12-06 1985-03-05 Magnum Jet, Inc. Modular through-tubing casing gun
GB2175674A (en) * 1985-04-30 1986-12-03 Vetco Ltd C E An explosive cutting device
US5564499A (en) * 1995-04-07 1996-10-15 Willis; Roger B. Method and device for slotting well casing and scoring surrounding rock to facilitate hydraulic fractures
US5797464A (en) * 1996-02-14 1998-08-25 Owen Oil Tools, Inc. System for producing high density, extra large well perforations
EP0846838A2 (en) * 1996-12-04 1998-06-10 Halliburton Energy Services, Inc. Methods and apparatus for performing explosive cutting operations in a subterranean well
GB2342144A (en) * 1998-09-30 2000-04-05 Western Atlas Int Inc Shaped charges
GB2346633A (en) * 1999-01-15 2000-08-16 Baker Hughes Inc Window forming by flame cutting

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
WALTER, W.P. AND ZUKAS J.A.: "Fundamentals of shaped charges", 1989, ISBN: 0471621722

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Publication number Publication date
GB0102913D0 (en) 2001-03-21

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