RU2445433C1 - Stabilising two-stage cutting bit - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: bit is divided into stages - an under-reaming one with a tail and a stabiliser and a lower spudding one one with a stabiliser, every of which is made in the form of independent solids of revolution arranged coaxially, at the same time cutting speeds of cutting elements of under-reaming and spudding stages that are most remote from the longitudinal axis do not exceed critical values, besides, stabilisers equipped with highly resistant rods, have calibrating effect.

EFFECT: improved wear resistance and running time of a bit in interbedding rocks, including alternations of VI-IX categories by drillability, with preservation of borehole verticality.

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Description

The invention relates to the field of drilling wells with cutting bits and can find application in the mining and oil and gas industries when drilling wells for various purposes. The cutting-type two-tier chisel is designed for drilling with a downhole motor in rocks above average and strong.

Known multi-tier chisel cutting type (see patent for invention of the Russian Federation No. 2310732. Multi-tiered chisel cutting type / Tretyak A.Ya., Chikhotkin V.F., Litkevich Yu.F., Aseeva A.E. Application 2006100565/03 (000634) dated January 16, 2006; publ. November 20, 2007; Bull. No. 32), intended for drilling wells for various purposes in rocks of VI-VIII categories for drillability.

Disadvantage: short cone-shaped tiers during drilling of alternating (layered) rocks are unstable at the bottom. This causes vibration of the cutting elements and can lead to breakage.

Also known is a stabilizing drill bit Speed Drill DPI (see Patent US 5803196. Stabilizing drill bit / Coy M. Diamond Products International (Houston, TX). Appl. No .: 08/655988. Filed: May 31, 1996. Fielder September 8, 1998), adopted by us as a prototype.

Disadvantage: different cutting speeds by cutting elements fixed on the drill and drill parts of the bit lead to uneven wear (predominant wear of the cutting elements of the drill part that are farthest from the axis). This limits bit production due to diameter loss.

The objective of the invention is to increase the wear resistance and production time of the bit on the alternating rocks while maintaining the verticality of the wellbore due to the fact that the stabilizing two-tier bit of the cutting type is divided into tiers - drilling from shanks and a stabilizer and lower drilling with a stabilizer, each of which is made in the form of independent bodies of revolution located coaxially, while the cutting speeds furthest from the longitudinal axis of the cutting elements of the drilling and drilling tiers do not exceed critical values.

The invention is illustrated in figures 1 and 2.

Figure 1 shows the stabilizing two-tier chisel with a planetary gear (associated rotation of tiers).

Figure 2 presents the bit with a planetary gear (counter rotation of tiers).

To ensure the drive of independent tiers of a stabilizing two-tier bit of cutting type II, a planetary gear I is placed above it, which is not a protected element.

The stabilizing two-tier chisel is divided into tiers made in the form of independent bodies of revolution and arranged coaxially - drilled with a shank 1 and stabilizer 2 and drilled with a stabilizer 5. Shank 1, which has a locking thread (not marked), is mated with a stabilizer 2 of the drilling tier. The cutting blades 3 of this tier are equipped with highly resistant cutting elements 4. The drilling tier with a stabilizer 5 and cutting blades 6 equipped with highly resistant cutting elements 7 rotates to the right with an angular speed ω ₁ , receiving a drive from the downhole motor (not shown) through the central shaft of the gearbox 8. 10 - the Central gear wheel with the number of teeth z _a ; 11 - ring gear with the number of teeth z _b . The drill tier rotates with an angular velocity of ω ₂ , receiving a drive from carrier 9 through the rotating satellites 12 of the planetary gear I.

Stabilizers 2 and 5 are spiral gage surfaces equipped with highly resistant pins 14. The stabilizers 2 and 5 increase the contact area with the walls of the well.

If the axis of the rotating satellites 12 is fixed in the stationary housing 13 of the planetary gearbox, then the drilling tier rotates to the left with a lower frequency. Wherein

i = Z _b / z _a ,

where i is the gear ratio of the planetary gear;

z _b - the number of teeth on the ring gear of the planetary gear;

z _a - the number of teeth on the Central wheel of the planetary gear.

If the axis of the rotating satellites 12 is fixed in the rotating part of the gearbox (on carrier 9), then the tiers of the bit will rotate along the way (to the right) with different frequencies. Wherein

i = z _b / z _a +1,

where i is the gear ratio of the planetary gear;

z _b - the number of teeth on the ring gear of the planetary gear;

z _a - the number of teeth on the Central wheel of the planetary gear.

When the drilling line is rotated with an angular velocity ω ₁ and the axial movement of the bit, the cutting blades 6 are drilled into the face, expanding as the well moves up to a diameter d determined by the position of the extreme cutting elements 7 located in the upper parts of the cutting blades 6. Since the cutting blades 6 consist of several cutting elements 7 of the drilling tier, and the cutting blades 3 consist of several cutting elements 4 of the drilling tier, located at different distances from the axis of rotation, their cutting speed as they are removed I increase from the axis, approaching its critical values, depending on the strength of the rocks and the wear resistance of the weapons. The cutting elements 4 and 7 may be diamond carbide inserts (ATP), Polycrystalline Diamond Cutter (PDC) or the like.

,The instantaneous drilling speed of the stabilizing two-tier bit V _mb , mm / s, is determined by the possible instantaneous drilling speed of the drilling line

,

where V _mb - instantaneous drilling speed, mm / s;

S _s - the intensity of the introduction (supply) of the drilling line, mm / rev;

n _s - rotational speed of the drilling line, r / s;

T _s - the time of one revolution of the drilling line, s.

During T _{z, the} entire bit makes axial movement S _z , and each blade of the drilling tier passes part of its revolution during the same time, cutting chips with thickness h = S _z with an instant drilling speed of V _mb .

Equality of instantaneous drilling speeds of various tiers of a bit

V _mb = S _s · n _s = S _p · n _p = const,

where V _mb - instantaneous drilling speed, mm / s;

S _s - the intensity of the introduction (supply) of the drilling line, mm / rev;

n _s - rotational speed of the drilling line, r / s;

S _p - the intensity of the introduction (supply) of the drilling line, mm / rev;

n _p - the frequency of rotation of the drilling line, rpm, is provided by varying the frequency and intensity of penetration, which makes it possible to coordinate the drilling speed of the rapidly rotating inner part of the bit and the slowly rotating outer part.

At these rotational speeds, for one revolution of the drilling tier, the bit will move along the axis of rotation by the value of S _p , mm / rev, and the drilling tier will turn only a part of the revolution, and in order for the face to be completely processed, it is necessary to have a number on the drilling tier blades z _p determined by the dependence

,

,

where z _p - the number of cutting blades of the drilling tier;

z _z - the number of cutting blades of the drilling tier;

n _s - rotational speed of the drilling line, r / s;

n _p - the frequency of rotation of the drilling tier, rpm

The value of the critical cutting speed V _cr - the main limitation of the scope of cutting bits on rocks above average strength and strong. The diameter of the bit at which the cutting element reaches a critical cutting speed at a rotational speed of n _s is called the limit (diameter d).

The rotational speed of the drilling tier having the largest diameter D,

,

,

where n _p is the rotational speed of the drilling tier, rpm

D is the maximum diameter of the drilling tier, mm;

d is the maximum diameter of the drilling line, mm;

n _s - the frequency of rotation of the drilling line, rpm

The cutting elements of the drilling line located at large radii will have a cutting speed determined by the dependence

,

,

where V _rez1 - cutting speed of the elements of the drilling line, m / s;

π is the mathematical constant;

d is the maximum diameter of the drilling line, mm;

n _s - the frequency of rotation of the drilling line, rpm

Its value does not exceed the critical value of the cutting speed.

With the gear ratio i = z _b / z _a (i = z _b / z _a +1), the cutting speed by the cutting elements of the drilling tier, the farthest from the axis of rotation, is significantly less than the critical value

where V _rez2 - cutting speed of the elements of the drilling tier, m / s;

π is the mathematical constant;

D is the maximum diameter of the drilling tier, mm;

n _s - the frequency of rotation of the drilling line, rpm

Thus, the bit does not have wear on the cutting elements farthest from the axis of rotation. The cutting elements of the boring and boring tiers wear out with the same intensity, thereby increasing the overall life of the bit.

Claims (1)

A stabilizing two-tier cutting bit, including a shank, lower drilling and upper drilling with stabilizers parts, which consist of a series of symmetrically arranged cutting blades, which, in turn, include radially arranged cutting elements, characterized in that the bit is divided into tiers, each of which are made in the form of independent bodies of revolution located coaxially, while the cutting speeds furthest from the longitudinal axis of the cutting elements of the boring and boring tiers n do not exceed critical values, and stabilizers equipped with highly resistant pins have a calibrating effect.

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