RU2083797C1 - Device for cutting out section of pipe in casing string - Google Patents

Abstract

FIELD: oil and gas industry. SUBSTANCE: device is used to make easier initial drilling of incline or horizontal bore-hole from vertical well. Device has charge of explosive material located in body and also selection of cumulative cones built in explosive charge. Cumulative cones are located along spiral lines of right-hand and left-hand directions. Distance between adjacent cumulative cones is not over three radii of cone base. When device is in operation, cumulative jets created at points of location of cumulative cones break holes in casing string thus making it weaker. Simultaneously blasting products of explosive charge extend pipe. In result of such combined action on pipe wall, cracks appear at weak points and pipe is destructed along cracks. Section of well at preset location is made free for initial drilling of incline or horizontal well. EFFECT: high efficiency. 1 cl, 5 dwg

Description

 The invention relates to devices for fragmentary destruction of the walls of the casing of the well, in particular for drilling during the transition from a vertical wellbore to an inclined or horizontal wellbore.

 Known annular cumulative pipe cutter containing a tubular body, a block of explosive (EXPLOSIVES) with an installed cumulative metal facing of the wedge-shaped section with a cavity facing the walls of the body, and a system of explosive burst of explosives from its center [1] A disadvantage of the ring cumulative pipe cutter is that it can only provide an annular section of the well pipe. Such a cut does not provide for cutting a new wellbore when moving from a vertical well to drilling an inclined or horizontal wellbore.

 As a prototype, a device for cutting pipes [2] was selected, comprising a housing with initiation units installed in it and placed in the transverse planes of the main and additional penetrating punches in the form of linear cumulative explosive charges connected to the initiator with cumulative wedge-shaped facings. The penetrating punches are spaced along the height of the case, are evenly distributed along the azimuth and are displaced relative to each other, and the penetrators of each additional piercer are inclined by cumulative recesses towards the main piercer located between the additional ones, with the possibility of intersection of the transverse planes of symmetry of the linear cumulative charges of the main and additional piercers .

 The disadvantage of such a pipe cutter is that it provides only a narrow annular section of the casing pipe of the well. This size is not enough for drilling when moving from a vertical wellbore to drilling an inclined or horizontal wellbore.

 The objective of the invention is to provide a transition from a vertical wellbore to the drilling of a directional or horizontal wellbore, destroying the casing and, thus, freeing the wellbore in the required section of its length with a length of about several meters.

 The technical result that is achieved during the implementation of the invention is the fragmentary destruction of the pipe of the well at a given length.

 A device for cutting a section of a well string comprises a housing, an explosive charge with cumulative linings arranged uniformly around the circumference, spaced apart along the height of the housing and displaced in azimuth at adjacent levels.

 The difference from the prototype is that the cumulative facings are made in the form of funnels and are located in the explosive charge along intersecting helical lines of the right and left directions, and the distance between adjacent funnels does not exceed three radii of the base of the funnels.

 It is advisable to carry out the explosive charge as a compound of explosive shells surrounding the cumulative facings, explosive inserts between the marked shells, an inert material between them and an explosive rod located along the device’s soy for transmitting detonation.

 The technical result in the proposed device is achieved by the complex effect of the breakdown effect of cumulative linings, weakening the strength of the pipe walls, followed by stretching the pipe from the explosive impact of explosives, leading to its destruction into fragments.

 The implementation of cumulative facings in the form of funnels ensures their high breakdown effect relative to the wedge-shaped facings in the prototype.

 As already noted above, the column pipe undergoes a complex destructive effect under the action of the device: holes are burned in the pipe under the cumulative effect of cumulative funnels, and the pipe walls are stretched due to the integrated (high-explosive) action of explosives.

 The burning of holes with the help of cumulative funnels weakens the strength of the pipe, which leads to the rapid destruction of the walls in the form of cracks that appear between the holes burned in the walls during subsequent expansion of the pipe.

 With this complex destructive action, the placement of cumulative funnels along intersecting helical lines of the right and left directions provides such an arrangement of the holes formed in the walls of the pipe, which ensures the most effective weakening of the pipe strength.

 The holes are burned along intersecting helical lines of the right and left directions, which are transverse to the direction of expansion of the pipe walls, extending around the circumference. This arrangement of holes provokes the rapid occurrence of cracks between the holes and the destruction of the pipe walls into separate fragments in the form of a rhombus. Fragments of the pipe crumble down and free the section of the well for drilling from a vertical wellbore into a horizontal wellbore, i.e. allow to achieve the planned technical result.

 Limiting the distance between adjacent cumulative funnels to no more than three funnel radii provides a sufficient degree of weakening of the strength of the pipe walls and the appearance of cracks between the holes and the destruction of the pipe walls on the fragment when it expands.

 The execution of the explosive charge by a composite of explosive shells surrounding the cumulative linings, explosive inserts between the shells, an inert material between them and the explosive rod along the axis of the detonation transmission device provides a radical direction of the explosive detonation exit and explosive shells around the cumulative funnels and explosive inserts. This ensures the greatest efficiency of the breakdown action of cumulative funnels and the maximum tensile effect of the explosion on the destructible pipe of the well string, which reduces the total amount of explosives used.

 Note that the impact of cumulative funnels in the proposed device provides a weakening of the pipe strength, i.e. funnels have a new functionality.

 In FIG. 1 shows the proposed device for cutting a pipe section of a well string; in FIG. 2 design variant of the device when performing explosive charge composite; in FIG. 3 illustrates the nature of the destruction of the well pipe; in FIG. 4, 5 of a section along AA in FIG. 1 and BB in FIG. 2.

 The proposed device comprises a housing 1, a charge of BB 2, cumulative linings in the form of funnels 3 located in a charge of BB 2 along intersecting helical lines of the right and left directions, a detonator capsule 4 for initiating detonation and a bar of BB 5 for transmitting detonation to the charge of BB 2.

 The device operates as follows. The detonator capsule 4 is detonated, exciting the detonation of the BB 5 rod, which is transferred to the explosive 2 charge. The detonation wave approaches the cumulative funnels 3. The funnels collapse, forming cumulative jets.

 Cumulative jets have a high burning effect and form holes in the walls of the pipe. Then, as a result of the integral (high-explosive) action of the explosion of the explosive charge 2, the pipe expands in radius at a speed of 0.5-1 km / s and the pipe walls are stretched. The strength of the pipe walls after burning holes in it is reduced. As a result of this, the expansion of the pipe leads to the rapid emergence of cracks along helical lines along which holes are formed, since they are transverse to the extension of the pipe walls in a circular direction. The holes burned in the walls are distributed along the pipe along intersecting helical lines of the right and left directions. Therefore, the appearance of cracks between the holes leads to the destruction of the wall into fragments in the form of a rhombus.

 After reducing the pressure of the products of the explosive explosion, fragments of the pipe crumble to the bottom of the well and release the walls to drill the transition to a directional or horizontal wellbore.

 A variant of using a device with a smaller number of explosives is implemented in the structural diagram shown in FIG. 2.

 The proposed device in this design contains a housing 1, a composite explosive charge containing cumulative linings in the form of funnels 3 located along intersecting helical lines of the right and left directions, inert material 4, inserts BB 5 between the shells of BB 2, a detonator capsule 6 for initiating detonation , bar BB 7 for transmitting detonation to the shells of BB 2 and inserts from BB 5.

 The device operates similarly to the device in FIG. one.

 Tests were carried out on the model of the proposed device having cumulative funnels made of copper with a diameter of 38 mm at the base, with destruction of the steel walls of the pipe 14 mm thick, the outer diameter of the pipe was 120 mm. Tests have confirmed the nature of the destruction of the wall by the combined effect of cumulative funnels and the explosive action of an explosion. The walls were divided into fragments along cracks arising between the holes formed by the cumulative effect of the funnels. The maximum fragment size was 50 mm.

 The proposed device in comparison with the prototype has a technical and economic advantage in that it provides fragmentary destruction of the section of the steel pipe of the well several meters long, which facilitates the transition from a vertical well to drilling an directional or horizontal wellbore.

Claims (2)

 1. A device for cutting a pipe section of a well string containing a housing, an explosive charge with cumulative linings arranged uniformly around the circumference, spaced apart along the height of the body and displaced along azimuth at adjacent levels, characterized in that the cumulative linings are made in the form of funnels and are located in explosive charge along intersecting helical lines of the right and left directions, and the distance between adjacent funnels does not exceed three radii of the bases of the funnels.  2. The device according to p. 1, characterized in that the explosive charge is made of shells surrounding the cumulative lining, inserts in an inert material between the shells and a rod located on the axis of the device.

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