초록 ▼

The invention relates to a perforating gun used for hydraulic fracturing applications in a wellbore and has an outer tube having several recesses of a second kind. The recesses of a second kind are configured to absorb shock waves from a shape charge in the perforating gun to reduce the numbers of c

The invention relates to a perforating gun used for hydraulic fracturing applications in a wellbore and has an outer tube having several recesses of a second kind. The recesses of a second kind are configured to absorb shock waves from a shape charge in the perforating gun to reduce the numbers of cracks that form on the perforating pun. In some embodiments, the recesses of a second kind have a variety of shapes and sizes to aid in the absorption of shock waves.

대표청구항 ▼

1. A perforating gun, comprising: a) an outer tube which is a tubular housing of the perforating gun with a wall thickness and an outer surface, and the outer tube having a plurality of first recesses on the outer surface, wherein each first recess has a first depth that is less than the wall thickn

1. A perforating gun, comprising: a) an outer tube which is a tubular housing of the perforating gun with a wall thickness and an outer surface, and the outer tube having a plurality of first recesses on the outer surface, wherein each first recess has a first depth that is less than the wall thickness of the outer tube, andb) an inner tube within the outer tube which is a charge holder that holds a plurality of shape charges,wherein each first recess corresponds to one shape charge and each shape charge has an opening directed to a corresponding first recess so that after detonation of the shape charges a high pressure and a high speed jet is generated and directed to the corresponding first recess,the outer tube having a plurality of second recesses on the outer surface, wherein each second recess has a second depth that is less than the wall thickness of the outer tube, wherein each second recess forms a continuous edge with the outer surface of the outer tube. 2. The perforating gun as claimed in claim 1, wherein the first recesses have a first recessed volume and the second recesses have a second recessed volume, wherein the first recessed volume of the first recesses is greater than the second recessed volume of the second recesses. 3. The perforating gun as claimed in claim 1, wherein the outer tube extends in an axial direction with a length L, the second recesses are arranged in an offset in the axial direction along the length L and an offset along a circumference direction of the outer tube. 4. The perforating gun as claimed in claim 3, wherein the offset in the axial direction between two adjacent second recesses is at least equal to and at most two times a diameter of a second volume of the second recesses; andthe offset in the circumference direction between two adjacent second recesses is at least three times and at most five times the diameter of the second volume of the second recesses. 5. The perforating gun as claimed in claim 1, wherein the second recesses are constituted conically with two V-shaped legs and an opening with an angle αbetween the legs between 30° and 150°. 6. The perforating gun as claimed in claim 1, wherein the second recesses have a shape selected from the group consisting of U-shaped, cup-shaped, polygonally shaped or cuboid shaped. 7. The perforating gun as claimed in claim 1, wherein the second recesses have a shape selected from the group consisting of U-shaped and cup-shaped and constituted with a valley and two hills extending from the valley in axial direction, the valley having a bottom directed radially inward to the tubular housing and the hills having tops extending radially out-wards to the tubular housing. 8. The perforating gun as claimed in claim 1, wherein the tubular housing is made of steel having a yield strength of at least 500 MPa. 9. The perforating gun as claimed in claim 1, wherein the tubular housing is made of high strength steel having a yield strength of at least 900 MPa. 10. The perforating gun as claimed in claim 1, wherein the tubular housing is made of ultra-high strength steel having a yield strength of at least 1200 MPa. 11. The perforating gun as claimed in claim 1, wherein the first depth of the first recesses is greater than the second depth of the second recesses. 12. The perforating gun as claimed in claim 1, wherein the outer tube extends in an axial direction with a length L, wherein at least some of the first recesses and at least some of the second recesses alternate along a first line that is parallel with the axis direction along the length L. 13. The perforating gun as claimed in claim 12, wherein at least some of the first recesses and at least some of the second recesses alternate along a second line that is parallel with the axis direction along the length L, wherein the first line and the second line are positioned on opposing sides of the outer tube. 14. The perforating gun as claimed in claim 13, wherein first recesses of the first line are positioned opposite second recesses of the second line, and second recesses of the first line are positioned opposite first recesses of the second line. 15. The perforating gun as claimed in claim 1, wherein at least some of the second recesses are arranged in an offset along a circumference direction of the outer tube, wherein at least one second recess is offset from at least one first recess by between 60 degrees and 120 degrees along the circumference direction of the outer tube. 16. The perforating gun as claimed in claim 1, wherein the first recesses have an initial shape in a pre-detonation state that is distinct from a final shape in a post-detonation, and the second recesses have an initial shape in the pre-detonation state that is substantially similar to a final shape in the post-detonation state. 17. The perforating gun as claimed in claim 1, wherein multiple second recesses are offset from each other and from each first recess along a circumference direction of the outer tube. 18. The perforating gun as claimed in claim 1, wherein at least three second recesses are offset from each other and from each first recess along the circumference direction of the outer tube. 19. The perforating gun as claimed in claim 1, wherein each continuous edge of each second recess is a closed shape and defines a perimeter of each second recess.