RU2661515C1 - Mechanisms for feeding drill bits - Google Patents

Abstract

FIELD: drilling of soil or rock.

SUBSTANCE: invention relates to drilling techniques, in particular to hydraulic mechanisms for feeding drill bits. Mechanism for feeding the bit is telescopic system installed between drill string and bottom hole assembly, and includes prefabricated cylindrical body with internal splines, hollow rod with piston in upper part and outer splines cooperating with body internal slots. Stem and piston have the same outer diameters forming gap with inner surface of cylindrical body. On outer surface of piston and on inner surface of lower part of the body, sealing assemblies are installed forming together with body inner surface and outer surface of rod is sealed chamber filled with oil, in which there is splined joint.

EFFECT: technical result is high reliability of device.

1 cl, 2 dwg

Description

The invention relates to drilling equipment, in particular to hydraulic mechanisms for supplying drill bits, allowing you to continue drilling directional or horizontal sections of the wells with increasing friction of the drill string against the wall of the well. Along with this, when the column is broken, impacts of the bit against the bottom and a sharp increase in torque on the bit are excluded, which leads to an increase in the durability of the equipment in the well.

A device for loading a bit is known (ed. St. SU 1350323, priority 13.08.1985), in which a pump wheel with vanes is fixed on a hollow shaft connected to a downhole motor shaft and a chisel. Centrifugal shutoffs are installed on the wheel, overlapping the annular gap during rotation of the shaft and pressed against the shaft when rotation is stopped. A disadvantage of the known device is that when lowering the layout or lifting the pump wheel may be damaged or cause a sticking tool.

Another disadvantage of the known solution is that when drilling the wheel is in the zone of upward flow of fluid after the bit, and the pump blades with blocked channels it will not be able to provide loading of the bit, rather, there will be unloading of the bit.

There is another device for creating axial load on the bit (ed. St. SU 1514902, priority 11/17/1987), comprising a housing connected to the motor shaft. A cylindrical bore is made in the housing, into which a hollow rod with a piston is inserted in the upper part, which has a thread in the lower part for connection with a chisel. In the middle part of the rod, having a square shape in cross section, centralizers are placed that rotate together with the rod and prevent it from bending, the load on the bit is created when the washing fluid enters the body boring and creates pressure through the piston on the rod and bit.

A disadvantage of the known solution is the loss of significant pressure of the flushing fluid spent on the sudden expansion of the flow at the entrance to the bore and the subsequent narrowing of the flow at the entrance to the Central hole of the rod, as well as losses during the movement of the stream in the Central hole of small diameter inside the rod.

Another disadvantage of the known device is that the centralizers on a long rod do not allow you to control the path of the well and can lead to damage to the rod.

The closest solution to the invention is patent RU 2164582 C2 (priority 16.06.1999, authors: Baldenko D.F. et al.), Which shows the layout of the bottom of the drill string, including a telescopic system installed between the drill string and the VZD, consisting of a cylinder and a piston with a hollow shank located inside it, and the cylinder is connected to the drill string, and the piston with the shank to the engine body. At the upper end of the piston, a landing seat is made to accommodate the nozzle. Holes are made in the lower part of the cylinder, communicating its internal cavity with the annulus. In the bore of the lower part of the cylinder, a spline or other connection is made with the piston shaft to transmit torque. When the drilling fluid is supplied, the pressure determined by the difference in the engine and the bit, as well as in the nozzle and the bore of the piston shaft, is transmitted to the engine housing and to the bit.

A disadvantage of the known solution is that the piston and the spline (or other) connection of the cylinder with the piston for transmitting torque operate in a hydroabrasive medium, which leads to their rapid wear and loss of characteristics (axial force on the bit and transmission of torque). Another disadvantage of the known device is the large pressure loss on the sudden expansion and narrowing of the flow, which do not create an increase in the load on the bit, but only excessively load the mud pumps, which reduces their resource.

The objective of the invention is to increase the performance of drilling wells while increasing the reliability of the device, increasing the resource of the drilling tool.

The technical result of this device is to increase the technical and economic performance of drilling and the prevention of complications and accidents of the drilling tool, the creation of a durable hydraulic bit feed mechanism, installed in the layout of the bottom of the drill string, using the minimum additional pressure (in excess of the required for the operation of the engine, drill bit and other devices, included in the layout of the bottom of the drill string, for example, a telemetric monitoring system) to increase the performance of the drill I deviated and horizontal wells, increasing resource cutter tools and equipment, which is part of the BHA.

The specified technical result is achieved due to reliable sealing of the chamber, in which the piston with the rod and the spline connection of the rod with the body of the bit feed mechanism are located. In addition, measures have been taken to minimize the pressure drop in the bit feed mechanism (MPD) itself in order to reduce the load on the mud pumps during MPD operation.

To achieve the specified technical result in the bit feed mechanism, including a prefabricated cylindrical body with internal splines connected to the upper part of the drill string, a hollow rod with a piston in its upper part and external splines interacting with the internal splines of the body, connected to the lower part with the layout of the bottom of the drill the columns, rod and piston have the same outer diameters, forming a gap of not more than 0.5 mm per diameter with the inner surfaces of the cylindrical body, and on the outer surface On the piston side and on the inner surface of the lower part of the housing, sealing units are made, which form, together with the inner surface of the housing and the outer surface of the stem, an airtight chamber filled with oil, in which there is a spline connection.

Distinctive features of the invention is that the rod and piston have the same outer diameters, forming a gap of not more than 0.5 mm per diameter with the inner surface of the cylindrical body, and on the outer surface of the piston and on the inner surface of the lower part of the housing there are sealing units forming together with the inner surface of the housing and the outer surface of the stem is a sealed chamber filled with oil, in which there is a spline connection.

Due to the presence of these features, the proposed design increases the resource and reliability of the bit feed mechanism (stability of the axial force on the bit and stability of torque transmission is maintained), increases the technical and economic performance of drilling and prevents complications and accidents of the drilling tool.

The drawings illustrate the essence of the invention.

In FIG. 1 shows a fragment of the layout of the bottom of the drill string (BHA) with a bit feed mechanism (MTD);

in FIG. 2 shows a transverse section through the MTD in section BB.

The bit feed mechanism (Fig. 1) contains a tubular outer casing consisting of tapered threads of a sub 1 connected to each other, connected by a thread 2 to a drill string 3, a upper casing 4, a sub 5 with internal slots, and a lower casing 6. Inside the tubular the housing is located rod 7 with external slots that are responsive to the slots of the sub 5, and a thread 8 for connecting to the body of the downhole motor 9 (or a telesystem, if any). A piston 10 with a sealing assembly 11 is screwed on top of the rod 7. A sealing assembly 12 is also made on the lower case 6. The existing space between the stem and the housing is filled with lubricant (oil, grease) through holes 13 and 14. The piston 7 and piston 10 have the same outer diameters. The sliding surfaces on the upper case 4 and on the rod 7 in contact with the sealing units 11 and 12 have equal diameters D, which are hardened (for example, hard chrome plated) and polished, thereby achieving a significant increase in resource. The equality of the diameters of the sealing units D when moving the rod 7 with the piston 10 ensures a constant lubricant volume between the tubular outer casing and the rod, which leads to a constant oil pressure and unimpeded movement of the rod 7 along the axis of the bit feed mechanism by the amount of stroke C (Fig. 1). In addition, due to possible bends in the well trajectory, a sleeve 15 of antifriction material (for example, bronze) is installed near the sealing assembly 12, which acts as a radial rod support 7, and the rod contacting the support has an antifriction coating. To reduce pressure losses in the bit feed mechanism in the hollow stem 7, a central hole of maximum diameter is made, based on considerations of the strength of the stem. At the same time, at the upper end of the piston 10, the hole is tapered, as at the lower end of the rod 7.

The bit feed mechanism is intended mainly for working in horizontal and directional (with a large angle relative to the vertical) wells, as in vertical and small-angle wells, the bit is fed using a drawworks (weight of the tool on a hook). In the horizontal section, with its great length, the column lies on the wall of the well and under the action of friction or differential sticking, the weight of the tool may be insufficient to feed the bit. In this case, the hydraulic bit feed mechanism comes into operation.

The work of the bit feed mechanism is as follows. When the supply of the column is stopped for the above reasons, the flushing fluid continues to flow through the bit feed mechanism in the direction of arrow A (Fig. 1) to the lower layout elements (bit, downhole motor, telecontrol system) in which a certain pressure drop is triggered (6-10 MPa) . Due to the fact that the drill string is disconnected in the bit feed mechanism (the rod 7 is connected to a part of the string located below the bit feed mechanism and can be telescopically moved relative to the body elements of the device), the force of the pressure drop indicated above is equal to the product of the pressure drop by the piston area 10, determined diameter D, is transmitted to the bit (minus the friction forces of the equipment installed below the bit feed mechanism against the borehole walls). The drilling process continues until the C stroke of the bit feed mechanism is developed. Optimum stroke C is determined empirically. In the process of column advancement, in case of its suspension and disruption, the bit feed mechanism prevents the bit impact and its breakage on the bottom, as the rod 7 returns to its original position under the action of force from the bottom, with which the bit is in contact.

The table shows the calculated values of the forces acting on the stem 7 for various sizes of the bit feed mechanism (106, 120, 178 mm) at various pressure drops that are triggered in the lower part of the BHA.

An experimental batch of the described bit feed mechanisms in a dimension of 120 mm was made at Gidrobur-Service LLC (Perm). Comparative tests of engines with and without MTD working in similar conditions were carried out at the intervals of wells 695–966 m and 966–1260 m –– using MTD, 692–990 m and 990–1383.5 m –– without MTD. The results showed that when drilling wells, the average mechanical penetration rate increases by 8-10%, the bit wears out much less under the same drilling conditions.

Claims (4)

1. The feed mechanism of the bit, which is a telescopic system installed between the drill string and the layout of the bottom of the drill string, including a prefabricated cylindrical body with internal splines, a hollow rod with a piston in the upper part and external splines interacting with the internal splines of the housing, connected to the lower part with the layout of the bottom of the drill string, characterized in that the rod and piston have the same outer diameters, forming a gap with the inner surface of the cylindrical body, and on the sealing surface of the piston and on the inner surface of the lower part of the housing are sealed units that form, together with the inner surface of the housing and the outer surface of the stem, an airtight chamber filled with oil, in which there is a spline connection. 2. The bit feed mechanism according to claim 1, characterized in that wear-resistant polished coatings are applied on the inner surface of the upper body and on the outer surface of the lower part of the stem in contact with the sealing units. 3. The bit feed mechanism according to claim 1, characterized in that the diameter of the inner hole of the hollow rod is maximally increased to a size that allows it to maintain its strength at the maximum extension of the rod from the body. 4. The bit feed mechanism according to claim 1, characterized in that a radial rod support is installed in the lower part of the housing next to the sealing assembly.

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