RU2170319C1 - Tool for expansion of shaft of hole - Google Patents

Abstract

FIELD: mining industry. SUBSTANCE: proposed tool is made of milling cutter linked to shaft of hydraulic face motor whose frame is coupled to lower end of rod of piston mechanism whose body in its turn is joined to lower pipe of drill pipe string. Piston coupled to rod and stopper are housed in body of piston mechanism. Rod is smoothly bent in axial direction. Milling cutter is manufactured in the form of rolling cutter bit which outer surface has shape of ellipsoid and its symmetry axis is displaced in parallel with regard to axis of linking thread of body of milling cutter. EFFECT: enhanced functional efficiency of tool. 2 cl, 4 dwg

Description

 The invention relates to the mining industry, and in particular to the technical means used as part of the layout of the bottom of the drill string (BHA), with the help of which the expansion of the drilled oil and gas wells.

 Known designs of paddle and cone extenders, which are included in the BHA and with which cut individual intervals of production and technical columns, as well as expanding boreholes [1]. The expanders indicated in this information source work successfully, but they can only slightly increase the diameter of the wellbore. So, with the diameter of the body of the pipe-cutting expander 209.6 mm, the maximum diameter to which the previously drilled shaft can be expanded is respectively 464 mm when using the blade version of the extender and 381 mm when using the cone version.

 As the closest analogue (prototype) of the invention, a device for expanding a well can be adopted [2]. The known device includes a milling cutter, the housing of which is fastened to the lower end of the shaft of a downhole hydraulic motor (HLD) using a thread. The latter is connected with a piston mechanism, the housing of which, with its upper end, is fixed to the lower pipe of the drill pipe string.

 However, the known device due to its design features does not allow to significantly increase the diameter of a previously drilled wellbore.

 Meanwhile, the specific tasks of increasing the efficiency of oil and gas recovery in productive formations require an increase in the diameters of the boreholes of drilled wells to values of 2-2.5 m, which cannot be accomplished using well-known technical means.

 The objective of the invention is to increase the efficiency of the tool to expand the drilled wellbore.

 The essence of the proposed technical solution lies in the use of a cutter, the housing of which is fastened to the lower end of the hydraulic drive shaft with a thread, the housing of which is attached to the lower end of the piston rod. The housing of the latter with its upper end is fixed to the lower pipe of the drill pipe string. The piston rod is smoothly curved in the axial direction. The cutter is made in the form of a cone mounted rotatably relative to the cutter body. The outer surface of the cone is ellipsoidal. The axis of symmetry of the outer surface of the cone has a parallel displacement relative to the axis of the connecting thread of the cutter body, with which the latter is fixed on the lower end of the HPL shaft.

The invention is illustrated by drawings, where:
- in FIG. 1 shows the general layout of a tool for expanding a borehole (a piston with a rod in its lowest position);
- in FIG. 2 shows a piston mechanism with a rod smoothly curved in the axial direction;
- in FIG. 3 shows a cross section of the piston mechanism along the tetrahedral part of the rod and stopper in FIG. 2;
- in FIG. 4 shows a general view of the cutter, with which the side wall of the well is destroyed.

 The milling cutter 1 with an ellipsoidal rock-cutting outer surface is fastened with thread to the lower end of the hydraulic drive shaft, the housing 2 of which is attached with its upper part to the lower end of the piston rod 3, the housing 4 of which in turn is screwed with its upper part (through the connecting sub) is attached to the bottom pipe 5 of the drill string. The upper part of the rod 3 (for ease of manufacture) has a four- or hexagonal cross-section, and its lower part is cylindrical. The rod 3 in its lower cylindrical part is smoothly curved in the axial direction. In this case, the diameter and length of the cylindrical part of the rod 3, its wall thickness and radius of curvature are selected so that, with the axial overall length of the horizontal joint connected by a thread to the mill 1, the center of gravity moves away from the vertical axis (when the rod 3 is fully extended from the housing 4 ) would reach a predetermined (calculated) value.

 A piston 6 is installed on the piston rod 3 in the upper part of the piston mechanism. The inner surface of the housing 4 serves as a sliding direction for the piston 6. In the middle part of the housing 4 there is a four- or six-sided stopper 7, which receives the reactive moment from the housing 2 of the hydraulic valve. The rod 3 in its upper part has a section corresponding to (with easy-to-pass tolerance) section of the stopper 7. The body 4 in the lower (frontal) part has an opening coaxial to its outer diameter, which centers the lower cylindrical (smoothly axially curved) part along the axis of the body 4 rod 3 in the position where the piston 6 abuts against the inner end of the upper part of the housing 4. The rod 3 has a through axial channel 8, which connects the space above the piston 6 (inside the housing 4 of the piston mechanism) with the internal cavity of the drill pipe 5 and with the space inside the housing 2 of the engine. The space located under the piston 6, through the mounting holes in the stopper 7, the landing gaps between the stopper 7 and the four- or hexagonal outer surface of the upper part of the stem 3, as well as between the lower (frontal) part of the housing 4 and the cylindrical part of the stem 3 are hydraulically connected to the space located outside the housing 4 of the piston mechanism. On the housing 4 of the piston mechanism there is one or more screws 9, with which the rod 3 is fixed in the housing 4 in the position when the piston 6 is abutted in the inner end of the upper part of the housing 4.

 A single-cone mill 1 consists of a housing 10 and a roller cone rotating relative to it 11. The housing 10 of the mill 1 is fixed with its threaded sleeve to the lower end of the hydraulic drive shaft. The cone 11 on its ellipsoidal outer surface has wear-resistant inserts (pins or diamond carbide inserts), the purpose of which is to ensure the destruction of the side wall of the well. The internal cavity 12 of the cutter 1 is hydraulically connected through the axial channel in the hydraulic drive shaft and the channel 8 in the stem 3 to the internal cavity of the drill pipes 5. On the ellipsoid working surface of the cutter 11 there are flushing grooves 13 with channel fittings 14 that hydraulically communicate the internal cavity 12 with the space behind ellipsoidal work surface. The roller cutter 11 of the mill 1 with the help of roller 15 and lock ball 16 bearings is fixed on the housing 10.

 The axis of symmetry of the ellipsoidal outer surface of the cutter 1 is parallelly shifted relative to the axis of the thread, with which it is attached to the valve shaft, by up to 50 mm.

 On the lower pipe 5 is placed a blade stabilizer 17, centering the drill string in the production string.

 A tool for expanding a wellbore operates as follows.

 Before the descent of the tool into the wellbore, the rod 3 must be fixed in the housing 4 of the piston mechanism with the screws 9 in the idle position when the piston 6 is abutted in the inner end 10 of the housing 4, i.e. the piston 6 is in its highest position.

 The tool in the BHA on the drill string is lowered into the production string. The descent of the tool stops when the lower point of the cutter 1 reaches the lower mark of the interval from which to expand the wellbore.

After the tool is lowered to the calculated depth, a lead pipe is screwed onto the drill string, which is fixed in the wedges of the rotary table of the drilling rig. Then include mud pumps. Since a sufficiently large pressure drop (50-80 kgf / cm ² ) is triggered on the gas distribution unit and mill 1, a significant axial force starts to act on the upper end surface of the piston 6 (depending on the diameter of the piston mechanism from 5 to 25 tons). Under the action of this force, the ends of the fixing screws 9 are cut off and the piston 6 together with the rod 3 moves to its lowest position, at which the piston 6 abuts against the stopper 7.

 If the inner surface of the production string did not maintain the straightness of the axes of all components of the assembled tool, then the center of gravity of the cutter 1, due to the bending of the piston rod 3, would move 0.8-1.5 m from the axis of the wellbore. Since the production string holds the axis of the tool is straightforward, a significant lateral force appears on the ellipsoid outer surface of the mill 1 (on its pins). The drilling fluid coming through the drill pipes through the internal cavity of the channel 8 in the rod 3 is directed to the hydraulic control valve, then through the axial channel of its shaft to the internal cavity 12 of the mill 1, then through the nozzle channels 14 and the flushing grooves 13 of the mill 1 enters the internal cavity of the production string and rises to the surface in the annulus.

 Passing through the hydraulic drilling rig, the drilling fluid rotates its shaft and the cutter mounted on it 1. The driller turns on the rotary table drive of the drilling rig, which begins to rotate the drill string together with the piston mechanism housing 4, the stem 3 and the hydraulic motor housing 2 fully extended from it. In this case, the wear-resistant insert of the cutter 1 sequentially destroys the steel body of the casing string, cement stone, and then the rock that composes the borehole wall. The driller slowly and smoothly lifts the tool at a speed of 0.3 - 1.0 m / h (depending on the strength of the rocks that make up the productive thickness of the geological section).

 When the weapons of the cutter 1 are triggered, the drilling pumps are stopped, the tool is removed from the wellbore and the cutter 1 is replaced with a new one.

 The operation to expand the wellbore is repeated in the above sequence until the desired bore diameter is obtained in the interval of occurrence of the reservoir.

Sources of information
1. American technology and industry. Issue III. Chilton. International Company, 1977, p. 333-336.

 2. RF patent N 2096580 C1, E 21 V 7/28, publ. 11/20/97 (Bull. N 32).

Claims (3)

 1. A tool for expanding a borehole, including a cutter, the body of which is screwed to the lower end of the hydraulic downhole motor shaft associated with the piston mechanism, the housing of which, in turn, is fixed with the upper end to the lower pipe of the drill pipe string, characterized in that the milling cutter is made in the form of a cone mounted rotatably relative to the milling cutter body, and the hydraulic downhole motor housing is connected to the lower end of the piston rod, which is made axially curved.  2. The tool according to claim 1, characterized in that the outer surface of the cone has an ellipsoidal shape.  3. The tool according to any one of claims 1 and 2, characterized in that the axis of symmetry of the outer surface of the cone has a parallel offset relative to the axis of the connecting thread of the mill body, with which the latter is fixed on the lower end of the shaft of the hydraulic downhole motor.

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