Oil Well Perforators

Abstract

An oil and gas well shaped charge perforator capable of providing an exothermic reaction after detonation is provided, comprising a housing (2), a high explosive (3), and a reactive liner (6) where the high explosive is positioned between the reactive liner and the housing. The reactive liner (6) is produced from a reactive composition which is capable of sustaining an exothermic reaction during the formation of the cutting jet. The composition is a pressed i.e. compacted particulate composition comprising at least two metals, wherein one of the metals is present as spherical particulate, and the other metal is present as a non-spherical particulate. There may also be at least one further metal, which is not capable of an exothermic reaction with the reactive composition, present in an amount greater than 10% w/w of the liner. To aid consolidation a binder may also be added.

Claims

1. A method of using a compacted particulate reactive composition in an oil and gas well shaped charge perforator liner, the reactive composition being a composition of at least two metals and comprising a substantially spherical metal particulate and a non-spherical metal particulate.

2. The method of claim 1, further comprising: placing the shaped charge perforator liner within a housing of a shaped charge perforator; providing a high explosive material between the shaped charge perforator liner and the housing; positioning the shaped charge perforator in a saturated substrate of an oil or gas well; detonating the high explosive material; in response to detonating the high explosive material: causing an exothermic reaction of the compacted particulate reactive composition; producing an electron compound; and forming, from the compacted particulate reactive composition, a high velocity jet of material to penetrate into a well casing of the oil or gas well.

3. The method of claim 2, wherein the spherical metal particulate comprises aluminium, wherein the exothermic reaction involves an interaction between the non-spherical metal particulate and the aluminium, wherein the aspect ratio of the non-spherical metal particulate is greater than that of the aluminium, and wherein the shaped charge perforator liner comprises a threshold pressure of 6 GPa or less to cause the exothermic reaction.

4. The method of claim 2, further comprising: perforating the well casing of the oil or gas well so as to improve inflow from the oil or gas well.

5. The method of claim 2, wherein producing the electron compound comprises producing a Hume-Rothery compound.

6. The method of claim 2, wherein the housing is formed partially or wholly from a reactive composition, wherein the reactive composition comprises the composition of the shaped charge perforator liner; wherein the method further comprises: consuming the housing by the exothermic reaction.

7. The method of claim 2, wherein positioning the shaped charge perforator comprises positioning the shaped charge perforator in a down hole configuration.

8. The method of claim 2, wherein positioning the shaped charge perforator comprises positioning the shaped charge perforator such that, upon detonation, the high velocity jet of material expands substantially perpendicular to a sidewall of the well casing.

9. The method of claim 1, wherein the compacted particulate reactive composition comprises a substantially stoichiometric mixture of the at least two metals.

10. The method of claim 1, further comprising: coupling a plurality of shaped charge perforator liners within respective housings of respective shaped charge perforators; providing a high explosive material between the respective shaped charge perforator liners and their respective housings; positioning the plurality of shaped charge perforators within a perforator gun; positioning the perforator gun in a saturated substrate of an oil or gas well; detonating the respective high explosive materials; in response to detonating the high explosive materials: causing an exothermic reaction of the compacted particulate reactive composition; producing an electron compound; and forming, from the compacted particulate reactive composition, high velocity jets of material that penetrate into a well casing of the oil or gas well.

11. The method of claim 10, wherein positioning the plurality of shaped charge perforators comprises positioning the plurality of shaped charge perforators perpendicular to each other such that the respective high velocity jets will converge, intersect or collide at or near the same point.

12. A method of manufacturing a reactive shaped charge liner, the method comprising: providing a composition of at least two metals; and compacting the composition of at least two metals to form a liner, wherein the composition comprises a spherical metal particulate and a non-spherical metal particulate.

13. The method of claim 12, wherein compacting the composition of at least two materials forms a green compact.

14. The method of claim 12, wherein compacting the composition of at least two materials comprises compacting the composition of at least two materials in a die set.

15. The method of claim 12 wherein compacting the composition of at least two materials comprises compacting the at least two materials into a near net shape so as to allow sintering or infiltration processes to take place, wherein the near net shape provides for placement of the liner into a housing of a shaped charge perforator.

16. The method of claim 12, further comprising: providing at least one other metal, wherein the at least one other metal comprises a high density metal; and mixing and uniformly dispersing the high density metal within the composition.

17. The method of claim 12, further comprising: producing a layer of at least one further metal; covering the layer with a layer of the composition; and compacting the layers to form a consolidated liner.

18. The method of claim 12, further comprising: providing a binder material, wherein the binder material is a powdered soft metal or a non-metal material; mixing the binder material with the composition; and compacting the mixture of the binder material and the composition.

19. A method of testing samples of reactive liner materials for use in a method of improving fluid outflow from an oil or gas well comprising: placing a test sample in an explosive anvil system comprising a steel anvil, a steel cover plate, an explosive, and a detonator, wherein the test sample is placed in a recess, subjected to shock, and recovered for analysis, wherein the analysis comprises X-ray diffraction.

20. The method of claim 19, wherein the test sample comprises a compacted particulate composition comprising a spherical metal particulate and a non-spherical metal particulate.

Description

DESCRIPTION OF THE DRAWINGS

[0064] In order to assist in understanding the invention, a number of embodiments thereof will now be described, by way of example only and with reference to the accompanying drawing, in which:

[0065] FIG. 1 is a cross-sectional view along a longitudinal axis of a shaped charge device containing a liner according to the invention;

[0066] FIG. 2 is a sectional view of a well completion in which a perforator according to an embodiment of the invention may be used;

[0067] FIG. 3 is a schematic representation of an explosive anvil system used to test reactive compositions for use in the liner of the invention; and

[0068] FIG. 4 is an XRD trace for a non-spherical/spherical NiAl particulate composition tested in the system of FIG. 3.

DESCRIPTION OF THE INVENTION

[0069] FIG. 1 is a cross-sectional view of a shaped charge, typically axially-symmetric about centre line 1, of generally conventional configuration comprising a substantially cylindrical housing 2 produced from a metal (usually, but not exclusively, steel), polymeric, GRP or reactive material according to the invention. The liner 6 according to the invention has a wall thickness of typically 1 to 5% of the liner diameter, but may be as much as 10% in extreme cases and to maximize performance is of variable liner thickness. The liner 6 fits closely into the open end 8 of the cylindrical housing 2. High explosive material 3 is located within the volume enclosed between the housing and the liner. The high explosive material 3 is initiated at the closed end of the device, proximate to the apex 7 of the liner, typically by a detonator or detonation transfer cord which is located in recess 4.

[0070] One method of manufacture of liners is by pressing a measure of intimately mixed and blended powders in a die set to produce the finished liner as a green compact. Alternatively, intimately mixed powders may be employed in the same way as described above, but the green compacted product is a near net shape allowing some form of sintering or infiltration process to take place.

[0071] Modifications to the invention as specifically described will be apparent to those skilled in the art, and are to be considered as falling within the scope of the invention. For example, other methods of producing a fine grain liner will be suitable.

[0072] With reference to FIG. 2, there is shown a stage in the completion of a well 21 in which the well bore 23 has been drilled into a pair of producing zones 25, 27 in, respectively, unconsolidated and consolidated formations. A steel tubular casing 9 is cemented within the bore 23. In order to provide a flow path from the production zones 25, 27 into the annulus that will eventually be formed between the casing 9 and production tubing (not shown) which will be present within the completed well, it is necessary to perforate the casing 9. In order to form perforations in the casing 9, a gun 11 is lowered into the casing on a wireline, slickline or coiled tubing 13, as appropriate. The gun 11 is a generally hollow tube of steel comprising ports 15 through which perforator charges of the invention (not shown) are fired.

EXAMPLES

[0073] Experiments were conducted to compare the reactive behaviour of the following samples, using similar initial density and shock loading conditions: [0074] a NiAl composition comprising a 1:1 molar ratio of spherical Ni particulates and spherical Al particulates, each of size 7-15 micron. [0075] a NiAl composition comprising a 1:1 molar ratio of flaked Ni particulates (44 micron by 0.37 micron, aspect ratio 119:1) and spherical Al particulates (5-15 micron).

[0076] The TMD of all tests samples was about 60%.

[0077] Referring to FIG. 3, an explosive anvil system 30 was used to test the samples, the system comprising a steel anvil 31, a steel cover plate 32, SX2 explosive 33 and an RP80 detonator 34. The sample to be tested was placed in recess 35 in anvil 31.

[0078] Initial tests were conducted using a 6 mm thickness of SX2. The skilled person will realize that thresholds depend on the type of shock loading and accordingly, the loadings quoted in respect of the anvil tests do not necessarily equate with the loading in a shaped charge.

[0079] The samples were subjected to shock and recovered for analysis. It was found that the Ni flake/Al sphere sample according to the invention had undergone close to 100% reaction to form an intermetallic compound. X-ray diffraction (XRD) analysis confirmed that the main reaction products were NiAl and Ni.sub.2Al.sub.3, with traces of Ni.sub.5Al.sub.3 and Ni.sub.3Al (see FIG. 4).

[0080] In contrast, approximately 5% of the spherical Ni/spherical Al sample reacted to form an intermetallic compound. The test was repeated using a 9 mm thickness of SX2. It was found that increasing the explosive loading increased the extent of reaction to about 10%.

[0081] It can be concluded that, under identical loading conditions, a reactive composition comprising a spherical metal particulate and non-spherical metal particulate produces more energy. Conversely, a desired energy output can be obtained at a lower detonation threshold. It follows that a shaped charge liner according to the invention provides similar benefits. For small charges in particular, liners according to the invention can be used to maximize the volume of the shaped charge jet at high temperature, thereby ensuring that more thermal work is put into the target.

[0082] It will be understood that the present invention has been described above purely by way of example, and modification of detail can be made within the scope of the invention. Each feature disclosed in the description and (where appropriate) the claims and drawings may be provided independently or in any appropriate combination.