RU2191243C2 - Pipeless electric downhole motor - Google Patents

Abstract

FIELD: oil and gas industry, particularly, devices for well drilling and reaming by electric downhole motor on cable. SUBSTANCE: upper flange of electric motor body of downhole motor has bushing which is connected by means of axial rotation bearing to upper nonrotating part of electric downhole motor. Lower flange of electric motor body is added with a hollow cylinder to which external shaft and core drilling bit are secured. Attached to lower end of electric motor rotor hollow shaft is internal shaft with pilot drilling bit for drilling of central part of bottom hole. EFFECT: higher operating reliability and efficiency. 1 dwg

Description

 The invention relates to the oil and gas industry, and in particular to devices for drilling and expansion of wells by an electric drill on a cable rope.

 The closest technical solution to the invention is a device for drilling wells on a cable rope with local flushing, i.e. without flushing fluid reaching the day surface, in which the reactive moment is removed by using the inertia of the body of the drill assembly, which is alternately accelerated in both directions to a predetermined, predetermined speed by reversing the submersible motor from the surface.

 This electric drill, lowered to the bottom of the well, is able to destroy the rock with a rotating bit at a load equal to the weight of the unit. The bit is driven by an electric motor through a reduction gear. The unit is equipped with a two-stage centrifugal pump, a slurry pipe for collecting cuttings [1].

The disadvantages of this electric drill are:
1. Under the influence of alternating dynamic loads from the periodic reverse of the electric motor in the metal structures of the electric drill, the strength fatigue intensively increases at the places of bolted joints and especially at the junction of the electric drill with a cable rope.

 2. The insulation of the motor in severe starting conditions of periodic reverse is sharply weakened, which increases the likelihood of a breakdown on the housing and significantly reduces its service life. Both of these circumstances require the use of a more reliable and expensive engine.

 3. When the engine is reversed due to a slowing of the rotational speed and stopping of the bit at the time of the reverse, the average rotational speed will decrease and, therefore, the speed of the well’s bottom will slow down, ie drilling performance will decline.

 4. Considerable time is spent directly on reversing the electric drill.

 The objective of the invention is to increase the operational reliability and efficiency of the electric drill.

 The problem is solved in that the upper flange of the motor housing is provided with a sleeve, which is connected through an axial rotation support to a non-rotating part of the electric drill. A hollow cylinder is attached to the lower flange of the motor housing by means of a coupling, to which a core bit is attached. A hollow cylinder is attached to the lower end of the motor shaft by means of a coupling, to which the pilot bit is attached.

 When you turn on the electric motor, suspended on an axial support of rotation, its stator and rotor rotate in opposite directions. Together with them, the core and pilot bits also rotate in opposite directions. Thus, in the proposed electric drill, the pilot bit forms a continuous face, expandable by a core bit to the diameter of the electric drill body.

Simultaneous rotation of the rotor and stator in opposite directions:
1) allows you to use the reactive moment to perform useful work - the destruction of the rock at the bottom of the core bit;
2) excludes starting conditions due to the lack of reverse;
3) the absolute frequency of rotation of the bits is automatically reduced, which creates a more favorable mode of operation and increases the degree of use of the technical resource incorporated in the design of the drill bits.

 Distinctive features were not known to us from the patent and scientific and technical information, and in this regard, we believe that the technical solution that we claimed is new.

 The claimed combination of essential and distinctive features is unknown for this industry, and this allows us to conclude that the technical solution meets the criterion of "inventive step".

 The drawing shows a longitudinal section of a tubeless electric drill. It includes: an electric motor housing 1 with a flange 2 of a sleeve 3 mounted on its upper housing, a hollow rotor shaft 4, an axial rotation support (bearing) 5, a sub 6, a pipe 7 with holes 8 at its upper end, a detachable connection 9, the cable rope 10, coupling 11, inner shaft 12 of the pilot bit, pilot bit 13, external shaft 14 of the core bit, coupling 15, core bit 16, shaft 17 with blades, current supply 18, current-supply rings 19 (three pieces), holes 20 on lower end of the inner shaft 12 of the pilot bit, sealing glands 21, lubricator 22, sludge trap, made in the form of a sludge collection pipe 23, rotation support 24, the electric drill body 25.

When the electric drill is turned on, its inner and outer shafts 12 and 14 rotate in opposite directions, mutually balancing their reactive moments of rotation, for which it is necessary and sufficient to fulfill two conditions:
- moments of inertia of masses rotating in different directions should be equal to each other;
- The braking moments occurring on the pilot bit 13 and the core bit 16 must be balanced.

 The device operates as follows.

 An electric drill descends into the well on a cable-rope 10 wound on a winch drum. Before the pilot bit 13 and the core bit 16 come in contact with the face, the electric motor is turned on and the electric drill carefully lowers to the bottom of the well, axial load on the bits is created, and drilling begins.

 The particles of the destroyed rock (sludge) are carried out from under the bits from the bottom of the well with a flow of flushing fluid coming out of the flushing holes of the pilot bit 13 and the holes 20 on the inner shaft. Sludge with flushing fluid rises along the annular space between the electric drill and the well walls to the upper end of the collection pipe 23 and, due to a decrease in the velocity of the upward flow (due to an increase in the cross-sectional area of the annular space above its upper end), settles in it. The liquid purified from slag rises to the holes 8 of the pipe 7, below which a shaft 17 with blades (an axial pump) is installed in the bore of the sub 6 and is pumped again to the bottom of the well. The shaft 17 is mounted on the upper end of the sleeve 3 and rotates with it.

 After filling the sludge collection pipe 23 with the destroyed rock, the electric drill is removed from the well to clean it from the cuttings, replace the spent drill bits, and the drilling cycle can be repeated again.

 To ensure a more complete cleaning of the washing liquid from the particles of the destroyed rock, the holes 8 on the pipe 7 should be located above the upper end of the sludge pipe 23, and the greater the distance between these holes and the upper end of the sludge collection pipe, the better will be the cleaning of the washing liquid from sludge. For normal operation of the electric drill, the level of flushing fluid in the well should always be higher than the holes 8 in the pipe 7. To protect the motor and axial support from the effects of flushing fluid, the internal cavity of the housing 1 is filled with oil and equipped with a lubricator 22.

 The proposed electric drill can also be used when drilling on flexible pipes, which, with a large length of the column, can not absorb significant torques. In this case, the electric drill allows drilling using (for washing the bottom of the well and removing sludge from it) aerated fluid, foam systems or a gas agent, which are used to open horizons with low reservoir pressure on the bottom and reduce pollution of its natural permeability. In this case, the axial pump must be removed from the electric drill, the holes 8 on the pipe 7 must be plugged.

The claimed device in comparison with the prototype has the following advantages:
- there is no need to provide a reversing mechanism;
- there are no reactive moments on the cable rope;
- electric drill parts do not experience alternating loads;
- in more favorable conditions, the motor winding works;
- when the electric drill is operating in a non-reversible mode, less time will be spent on drilling a well;
- higher operational reliability;
- the life of the electric drill increases;
- when the electric drill is working on a string of flexible pipes, alternating torsional loads will not occur in it.

Sources of information
1. Stepanyants A. K. Opening of productive formations. M .: Nedra, 1968, p. 334.

Claims (1)

 Tubeless electric drill, including a chisel, gearbox, pump, electric motor, sludge trap, detachable connection for replacing units and a cable-rope, characterized in that the upper flange of the motor housing is equipped with a sleeve that is connected to the upper non-rotating part of the electric drill by an axial rotation support, the lower flange of the housing the electric motor is supplemented by a hollow cylinder, to which the external shaft and core bit is attached, to the lower end of the hollow shaft of the electric motor rotor is attached an internal shaft with a pilot bit for I'm drilling the central part of the bottom hole.