RU2769009C1 - Drill bit - Google Patents

Abstract

FIELD: drilling bits.

SUBSTANCE: invention relates to drilling bits. The drill bit includes a body with blades made on it, in which PDC cutters with a flat front face are placed. PDC cutters with a flat front edge are fixed on the blades from the center to the periphery in the diametral plane along two symmetrical logarithmic spirals with negative front angles varying from minus 30 degrees in the center to minus 10 degrees at the periphery with an interval of one degree in the form of a two-start "thread". In order to dampen vibration from torsional and longitudinal vibrations of the bit, which cause breakage of PDC cutters with a flat front face, as well as to increase the efficiency and service life of its work, a second row of PDC cutters with a convex conical shape is installed stepwise behind the PDC cutters with a flat front face. The second row of PDC cutters with a convex conical shape is located in the cutting lines, between the PDC cutters with a flat front edge. In the center, a PDC cutter with a convex cone shape is installed, ahead of the PDC cutters with a convex cone shape in height from 1 mm to 5 mm relative to the PDC cutters with a flat cutting edge, behind which the corresponding PDC cutters with a convex cone shape are installed.

EFFECT: creation of a drill bit that equally well destroys rocks from 5 to 9 categories in terms of drillability, as well as in increasing the mechanical speed of drilling rocks.

1 cl, 2 dwg, 1 tbl

Description

The invention relates to the field of application of a rock cutting tool for drilling wells for solid, liquid and gaseous minerals, namely, drilling bladed bits reinforced with diamond-carbide plates (ATP) or, as it is commonly referred to abroad, PDC.

A bit design is known (patent WO 2008/100455, published on 21.08.2008, IPC E21B 47/12; E21B 47/26), containing a body with PDC cutting elements placed on the blades. The disadvantage of this design is the lack of a systematic, schematic arrangement of the PDC cutting elements and, as a result, a low resource and work efficiency when drilling rocks.

A bit design is known (RF patent for utility model No. 119012, published on 10.08.2012, IPC E21B 10/43), containing a body with PDC cutting elements placed on the blades. The disadvantage of this invention is that this design is a core drill head, and not a bit, therefore, it is not possible at all to place PDC on the blades of this device in a logarithmic spiral, due to the narrow range of applicability.

Known bladed drill bit containing a body placed on the blades of the PDC (patent WO 2008/091654 published 31.07.2008, IPC E21B 47/12; E21B 47/26). The disadvantages of this design is that the PDC plates are located not in a logarithmic spiral in the diametrical plane of the working part of the bit and not at a negative rake angle from minus 30 degrees to minus 10 degrees. And this leads to a decrease in the resource and efficiency of the bit as a whole.

The closest technical solution to the proposed invention, adopted by the author as a prototype, is a bladed bit containing a body with PDC placed on the blades with flat cutters (patent No. 2694872, published on July 17, 2019, bull. No. 20). The disadvantage of this design is that the location of flat PDC cutters does not contribute to damping vibrations from torsional and longitudinal vibrations of the bit, causing their breakage, and also does not sufficiently contribute to increasing the efficiency and resource of its operation, due to the increased energy intensity of the rock destruction process. .

The technical task of the invention is the creation of such a bit that would effectively destroy rocks from 5 to 9 drillability categories, while the proposed design of the bit would help eliminate the above disadvantages.

The problem is solved due to the fact that the drill bit, including a body with blades made on it, on which PDC flat cutters are mounted, fixed on the blades from the center to the periphery along two symmetrical spirals with negative front angles varying from minus 30 degrees in the center to minus 10 degrees on the periphery of the bit with an interval of one degree in the form of a 2-start “thread” additionally contains a second row of flat PDC cutters located in the cutting lines between the flat PDC cutters, and in the center of the bit a PDC cone cutter is installed ahead of the cone cutters in height from 1 mm to 5 mm, depending on the category of rocks in terms of drillability.

The height of the PDC taper cutters (h) is set on the bit body depending on the category of rocks: soft (5-4 mm), medium (4-3 mm), hard (3-2 mm), very hard (2-1 mm ).

The height of PDC taper cutters over PDC flat cutters can be determined by the formula:

h=(V/N)/n,

where h - excess height, mm;

V - mechanical drilling speed mm/min;

N - bit rotation frequency, rpm;

n is the number of PDC flat cutters in the cutting line.

Installation in the second row of PDC cone cutters located in the cutting lines, between the flat PDC cutters on the bit blades and the PDC cone cutter in the center of the bit, leading them in height from 1 mm to 5 mm, depending on the category of rocks, will allow to achieve vibration damping arising from torsional and longitudinal oscillations of the bit, causing breakage of the cutters, as well as increasing the efficiency and its resource.

The installation of PDC cone cutters, the so-called indenters, in the second row, behind the flat PDC cutters, in a logarithmic spiral, with a height advance of 1 mm to 5 mm, will provide a local impact on rocks when drilling rocks, taking on all the main initial loads for the destruction of the bottom of the well. Thus, the PDC flat cutting cutters are partially released from the active phase of rock destruction. At the same time, the energy intensity of the rock destruction process is significantly reduced, since the stepped form of bottomhole formation in the well is less energy-intensive, helps to reduce vibration and, as a result, the mechanical drilling speed will be higher. In this regard, it can be concluded that there are “significant differences” in the proposed bit and that the patentability is “novelty”.

In FIG. 1 shows a general view of the drill bit.

In FIG. Figure 2 shows a diagram of the PDC installation on the blades of the second row bit, where number 1 shows the PDC cone cutters, number 2 shows the flat PDC cutters, number 3 shows the central cone PDC, number 4 shows flushing holes.

The drill bit (Fig. 1) includes a body 1 with blades 2 made on it, in which PDC cutting inserts 3 are placed, fixed on the blades 2 from the center to the periphery along two symmetrical logarithmic spirals with negative front angles varying from minus 30 degrees in the center to minus 10 degrees on the periphery with an interval of one degree in the form of a 2-start "thread". Flushing holes 4 are made in the body 1 for the passage of the flushing liquid. The second row of PDC cone cutters is shown under the numbers 6. The PDC cone cutter in the center of the bit is shown under the number 5.

The proposed drill bit works as follows. The flushing liquid intended for cooling the bit and transporting the destruction products to the surface of the well, moving through the rotating string of drill pipes, the body 1 of the drilling bladed bit and flushing holes 4, enters the bottom of the well. At the same time, due to axial loads transmitted to the bit through the drill string, PDC 3 flat cutters mounted on the blades from the center to the periphery along two symmetrical logarithmic spirals with negative front angles varying from minus 30 degrees to minus 10 at the periphery with an interval of one degree in in the form of a 2-start “thread”, smoothly entering the cutting line, excluding dynamic loads (vibration), they destroy the bottom of the well when drilling fractured and intermittent rocks. At the same time, the second row of PDC cone cutters located in the cutting lines between the flat PDC cutters and the PDC cone cutter in the center of the bit contribute to vibration reduction. Adjustment of cone cutters in height from 1 to 5 mm is carried out depending on the category of rocks in terms of drillability. At the same time, the flushing liquid, falling under the inclined plane of the flat cutters PDC 3, placed on the blades 2, is pressed into the destroyed rock during the rotation of the projectile and due to the hydrodynamic effect (a negative rake angle from minus 30 degrees to minus 10 degrees creates the effect of a viscous wedge , that is, it weakens it, creating an active fracture and pre-fracture zone, thereby reducing the energy intensity of the fracture process.With their spiral arrangement at the tool end, PDC 3 flat cutters actively contribute to the removal of destruction products from under the working end of the bit. destruction products, transports them to the wellhead through flush holes 4 to the surface in a turbulent mode.The turbulent bottomhole cleaning mode does not allow cuttings to re-enter under the PDC flat cutter.The second row of cone cutters is located stepwise, above the main PDC flat cutters, which contributes to the formation of a stepped bottom wells s. This design of the bit, in combination with a cone cutter in the center of the bit, helps to reduce the degree of vibration, reduce the energy intensity of the rock destruction process and increase the mechanical drilling speed.

The use of the proposed design will allow destroying rocks from 5 to 9 categories in terms of drillability and drilling in difficult geological conditions, increasing the mechanical speed, and also improving the technical and economic indicators of well construction.

Installing PDC plates on the blades of the drill bit at a negative front angle from minus 30° to minus 10 along two symmetrical logarithmic spirals in the diametral plane with an interval of one degree in the form of a 2-start “thread”, significantly increases the bit performance, as well as its life due to the exclusion of areas not covered by cutting elements.

The spiral arrangement of flat PDC cutters contributes to the active removal of destruction products from under the working end of the tool. The installation of flat cutters with the largest angle in the center of the bit contributes to a smooth entry into the cutting line, reducing dynamic loads (vibration), which increases the life of the bit.

When the bit is deepened in one revolution to a depth, the cutting elements are located at different radii and, rotating, pass the cutting path along trajectories of different lengths and with different angles of inclination. Therefore, to ensure equal conditions for the penetration of cutting elements into the rock, it is necessary that each flat cutter (PDC) has the same clearance angles. For this, it is necessary that the cutting element of the blade located at different radii have their own inclination angles in the longitudinal plane.

The arrangement of flat PDC cutters in the diametrical plane along two symmetrical logarithmic spirals provides complete coverage of the bottomhole with cutting lines and contributes to the creation of drilling fluid turbulence, which improves the quality of cleaning the bottomhole from cuttings. Thus, the turbulent flushing regime is already formed directly at the bottom of the well, which contributes to an increase in the ROP.

The use of the proposed design of the bit will allow to destroy rocks of intermittent hardness from 5 to 9 categories of drillability and to drill in difficult conditions of fractured rocks, increase the mechanical speed of drilling and the service life of the tool, increase the technical and economic indicators of drilling operations and efficiency in drilling deep and ultra-deep wells for oil and gas.

To increase the reliability of the bit, drilling and well-forming cutting elements are duplicated multiple times. The advantage of the technology of "screwing" into the face is carried out by reducing the axial load.

Evaluating all of the above, we can conclude that the proposed bit by design combines, in the form of a combination, all the innovative ideas known in the world in one product, therefore, it has a higher quality indicator of work and coefficient of performance (COP), (Table 1 ) and will allow to achieve an increase in the mechanical speed of drilling of rocks by 20 percent or more.

That is, the claimed solution for the alleged invention "Drill bit" satisfies the patentability condition "inventive step" and is a qualitatively new bit.

Claims (1)

Drill bit, including a body with blades made on it, in which PDC cutters with a flat front face are placed, while PDC cutters with a flat front face are fixed on the blades from the center to the periphery in the diametral plane along two symmetrical logarithmic spirals with negative front angles that change from minus 30 degrees in the center to minus 10 degrees at the periphery with an interval of one degree in the form of a two-start "thread", characterized in that in order to dampen vibration from torsional and longitudinal vibrations of the bit, which cause breakage of PDC cutters with a flat front edge, as well as increase efficiency and resource of its work behind the PDC cutters with a flat front edge, the second row of PDC cutters with a convex cone-shaped shape is installed stepwise, located in the cutting lines, between the PDC cutters with a flat front edge, and in the center the PDC cutter with a convex cone-shaped shape is installed ahead of the PDC cutters with a convex conical shape in height from 1 mm to about 5 mm relative to the PDC cutters with a flat cutting edge, behind which the corresponding PDC cutters with a convex conical shape are installed.

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