CN110145241B - A low torque diamond drill bit suitable for drilling in hard formations - Google Patents

Abstract

The invention discloses a low-torque diamond drill bit suitable for drilling a hard stratum, and belongs to the field of drilling. The drill bit mainly comprises a drill bit body, blades extending from the drill bit body or fixed on the drill bit body, water holes or nozzles, a runner and the like. The cutter blade is characterized in that rolling elements are arranged on the cutter blades, only the rolling elements are arranged on at least one cutter blade, or supports extending from the cutter blades are arranged in front of and/or behind at least one cutter blade, the rolling elements are arranged on the supports, and the rolling elements are arranged in grooves of the cutter blades or the supports. The invention can obviously reduce the sensitivity of the torque of the drill bit to the weight on bit, reduce impact damage and fatigue failure of cutting teeth and other downhole tools caused by torque fluctuation, prolong the service life of the drill bit, and improve the stability of the tool face in directional drilling so as to improve the directional efficiency.

Description

Low-torque diamond drill bit suitable for drilling hard stratum

Technical Field

The invention belongs to the technical equipment fields of petroleum and natural gas drilling engineering, mine engineering, building foundation engineering drilling construction, geological drilling, geothermal drilling, hydrologic drilling, tunnel engineering, shield, non-excavation and the like, and particularly relates to a drilling bit.

Background

The drill bit is a rock breaking tool used for breaking rock and forming a shaft in drilling engineering, and is commonly used as a polycrystalline diamond compact bit (PDC drill bit), a roller cone drill bit and an impregnated diamond drill bit. The PDC drill bit is the most commonly used drill bit in diamond drill bits, and is widely used in engineering such as oil and gas exploration, geothermal drilling operation and the like by virtue of the advantages of high mechanical drilling speed, long service life, low drilling cost and the like in soft to medium hard stratum by shearing rock by means of a polycrystalline diamond compact with high hardness, high wear resistance and self-sharpening capability. Fixed cutter bits, typically PDC bits, have a plurality of blades on which a plurality of cutting elements (for PDC bits, the cutting elements are primarily polycrystalline diamond compacts, compacts or PDC teeth) are disposed along the radial direction of the bit.

During the drilling process, the composite cutting teeth of the PDC drill bit penetrate into the stratum and drill forward under the action of the bit pressure and the torque, so that stratum stress is overcome. The PDC drill bit breaks the working characteristics of rock in a shearing mode, and compared with a rock breaking mode of impact rolling of the rock bit, the PDC drill bit has the advantage that required driving torque is larger. In the ideal drilling process, under a certain bit pressure, the PDC evenly bites into stratum with constant depth, and evenly scrapes and cuts the rock, so that torque feedback of the PDC tends to be in a stable state. However, due to the complexity of the downhole formation conditions, especially when drilling hard and soft staggered formations, the bit penetration depth frequently changes and the degree of vibration of the bit torque feedback is more severe. In severe cases, the drill bit penetrates too deeply into the formation, which may cause a drive torque to fail to drive the drill bit to rotate, resulting in stalling of the drill bit. The drill string continues to twist as driven by the rotary table. When the energy accumulated by the drill string is sufficient to overcome the torque of the interaction between the drill bit and the stratum, the drill bit is transited from a static state to a moving state, the accumulated energy of the drill string is released instantaneously, and the drill bit suddenly rotates at a speed which exceeds a plurality of times of a normal speed. This is the stick-slip phenomenon of the drill bit. The phenomenon is easy to cause high-speed rotation and array twisting of the drill bit and the drilling tool, so that the cutting teeth of the drill bit bear large circumferential impact load, and the drill bit is broken, damaged, broken and detached, and damaged by other downhole tools and measuring instruments, thereby seriously affecting the drilling efficiency. Meanwhile, the larger torque fluctuation also can cause the instability of the tool face in the directional drilling process, so that the tool face is difficult to put, and the construction progress is slowed down. In addition, since PDC bits are particularly sensitive to depth variations in penetration into the formation, combined with the complexity of the cutter interaction with the rock, the presence of longitudinal vibrations in the axial direction of the bit can also negatively impact bit life and rate of penetration.

Therefore, how to control the penetration depth of the drill bit into the rock, reduce the sensitivity degree of the drill bit torque to the drill pressure, eliminate the slip and jump of the drill bit, ensure that the drill bit torque is kept in a relatively stable motion state under the given drill pressure, and are important technical problems of prolonging the service lives of the underground drilling tool and the drill bit and improving the drilling efficiency.

Disclosure of Invention

The invention aims at: the low-torque diamond drill bit suitable for drilling hard stratum can remarkably reduce the sensitivity of the drill bit torque to the drilling pressure under the complex working condition, and improves the stability of torque feedback when the drill bit rotates to drill, so that impact damage and fatigue failure caused to cutting teeth and other downhole tools due to large torque fluctuation of the drill bit are reduced, the working stability of the drill bit is improved, and the service life of the drill bit is prolonged. In particular, in directional drilling, the low torque drill bit can improve the stability of a tool face during directional sliding drilling and improve the directional efficiency.

The aim of the invention is achieved by the following technical scheme:

A low torque diamond drill bit suitable for drilling hard stratum comprises a drill bit body, blades extending from the drill bit body or fixed on the drill bit body, a water hole or a nozzle, a runner and the like, wherein rolling elements are arranged on the blades, only the rolling elements are arranged on at least one blade, or a support extending from the blade is arranged in front of and/or behind at least one blade, the rolling elements are arranged on the support, and the rolling elements are arranged in grooves of the blades or the support.

The drill body, teeth, blades, water holes and nozzles according to the present invention are known in the art, and will not be described herein.

The cutting teeth arranged on the blades of the diamond drill bit can be PDC cutting teeth, impregnated cutting teeth or a combination of the PDC cutting teeth and impregnated cutting teeth. The impregnated cutting teeth can be arranged as impregnated vertical teeth, impregnated horizontal teeth or a combination of the impregnated vertical teeth and the impregnated horizontal teeth. For ease of description, the following replaces diamond teeth with PDC teeth, but is not limited to PDC teeth.

In the rock breaking process of the drill bit, rolling elements are arranged on the blades or the support of the drill bit, and the rolling elements can roll on the rock surface when contacting with the rock. On the one hand, when the rolling bodies contact or invade the stratum, the contact area of the rolling bodies and the rock is far larger than that of the sharp PDC teeth, and the specific pressure between the rolling bodies and the rock is relatively smaller, so that the rolling bodies provide a larger supporting surface which can contact with the rock at the bottom of the well for the drill bit, and the partial bit pressure exerted on the cutting teeth of the drill bit is shared, namely the penetration depth of the PDC cutting teeth is limited, so that the torque of the drill bit is reduced. In particular, the rolling bodies can freely rotate on the rock at the bottom of the well, rolling friction is formed between the rock and the rolling bodies, so that friction torque between the drill bit and the rock is reduced, and the overall torque of the drill bit is reduced.

Due to the complexity of the underground working condition during drilling, the rolling bodies are in direct contact with the rock, and certain wear resistance, pressure resistance and impact resistance are required, and the material can be impregnated material, artificial diamond, alloy steel, hard alloy, powder metallurgy material, metal composite material or surface sprayed with wear-resistant material and the like.

Preferably, the support is connected to two adjacent blades.

In the scheme, the original blade is not provided with the direct slot to serve as the support of the rolling element, so that the structural strength of the original blade is maintained, and meanwhile, the range of the installation position of the rolling element is wider and more flexible. And can set up the rolling element of bigger size according to the position space of support, better play the effect that reduces the moment of torsion to the drill bit.

Preferably, the relative height between the rolling elements and the cutting teeth of the drill bit is in the range of 0mm < H < 5mm.

In the above scheme, the cutting profile (also called crown profile) is one of important structural characteristics of the drill bit, reflects the working position and state of each cutting element on the drill bit for breaking rock at the bottom of the well, and is a structural characteristic which has important influence on the stratum adaptability and drilling performance of the drill bit. As shown in fig. 24, the current diamond bit cutting profile is parabolic in shape and generally includes five parts, an inner cone 120, a crown 121 (nose region), an outer cone 122, a shoulder 123 and a gage 124. It is assumed that the drill bit has a cutting plane passing through the bit axis and a point on the bit (referred to as the axis plane or axial plane passing through the point). When the drill bit rotates around the self axis under the condition of zero drilling speed, the tooth edge contour line of the cutting tooth and the cutting plane or the shaft surface intersect to form an intersection line, and the envelope line of the intersection line is called the shaft surface contour line of the cutting tooth or the envelope line of the cutting tooth. A normal line passing through any point on the envelope is referred to as a direction reference line passing through the point. The axial profile lines of all cutting teeth are collected together to form a bottom hole coverage map of the drill bit. Fig. 23, 24 are bottom hole coverage of rolling elements and PDC cutters in the bit axis plane. Due to the existence of the rolling elements, the drill bit has the advantages that the drill bit eating depth is effectively limited when the drill bit drills, the situation that the drill bit torque is variable due to overlarge eating depth or unstable eating depth in the drilling process of the drill bit can be effectively prevented, the service life of the cutting teeth can be well protected, the sustainable drilling capability of the drill bit is improved, and meanwhile the phenomenon that the tool face is difficult to control due to the fact that the torque of the drill bit is variable in directional drilling is effectively avoided. Different normal distances can be selected according to different stratum conditions so as to improve the adaptability of the drilling capability of the drill bit.

The patent specifies as follows: as shown in fig. 17, when a normal reference line passing through a point on the envelope line intersects the rolling element at a point in the axial plane, if the distance between the two points (normal distance) is zero, that is, the two points overlap, the relative height between the rolling element and the cutting tooth is defined to be zero; when the intersection point is located outside the envelope, the height between the intersection point and the envelope is defined as a positive value, namely the rolling element is higher than the cutting tooth; when the intersection point is located inside the envelope, it is provided that the relative height between the two is negative, i.e. the rolling element is lower than the cutting tooth. It is obvious that the present patent is not limited to the case where the relative height is only positive and negative, but includes the simultaneous presence of positive, negative or zero means, i.e., the rolling elements of the rolling elements protrude from the cutting tooth envelope in some areas, the rolling elements of the rolling elements are within the envelope in some areas, and the relative height of both in some areas is zero.

Preferably, the angle between the axis of the support body of the rolling element and the normal reference line at the intersection point of the envelope of the fixed cutting tooth is in the range of 0 DEG to 60 deg.

In the axial plane of the drill bit, the support body axis intersects the outer envelope line of the cutting teeth at a point, referred to as a reference point, where the cutting teeth normal reference line past the reference point forms an acute angle δ with the support body axis, as shown in fig. 23. The positive and negative prescriptions are: the reference line rotation delta clockwise about the reference point is positive when it coincides with the support axis, and negative instead. Different angles should be selected according to different application conditions.

Preferably, the rolling elements are arranged at different positions of the bit crown profile.

According to the scheme, the rolling elements are arranged in the inner cone area of the outline of the crown of the drill bit, so that the drill bit can be effectively prevented from being cored; the rolling elements are arranged in the crown region, can bear more drilling pressure, prevent the drill bit from being overstocked, and reduce torque fluctuation; because the outer cone area is the area with the largest rotation radius on the drill bit, the linear speed of the cutting teeth is high, so that the cutting teeth bear stronger impact load, and meanwhile, the cutting teeth in the area are the area with the largest contribution of the torque of the drill bit, and the rolling elements are arranged in the area, so that the torque of the drill bit and the impact load of the cutting teeth can be greatly reduced.

Preferably, the rolling elements are composed of rolling bodies and rolling supports, and the rolling bodies may be spherical, cylindrical, disc-shaped, drum-shaped, and combinations thereof.

In the scheme, the rolling elements and the rolling supports are arranged together to form the rolling elements, and the rolling elements are simple to process and convenient to assemble. The rolling bodies with different shapes are selected, and the contact mode and rolling mode of the rolling bodies and rock are different, so that different stratum conditions and drill bit performance requirements can be met, and the application range is wider. For example, the spherical rolling body has a working mode similar to a universal ball structure, namely, the rolling body can freely and flexibly rotate in the rolling support, so that torque fluctuation of the drill bit under a complex working condition can be greatly reduced; the cylindrical rolling bodies can improve the contact area between the cylindrical rolling bodies and rock, and can share larger impact load; the disc-shaped rolling bodies roll on the surface of the rock, so that the torque of the drill bit is reduced, and the blade edge of the disc can also invade the rock in a rolling mode and break (pre-break) the rock, so that annular grooves are formed on the surface of the rock at the bottom of the well, and the effect of assisting the cutting teeth of the drill bit in breaking the rock is achieved.

Preferably, the rolling elements are provided with sealing means.

According to the scheme, the rolling element is provided with the rolling element which can flexibly rotate to play a role in reducing torsion, and whether the rolling element can flexibly rotate is very critical to the effect in reducing torsion of the drill bit. Because the working condition of the drill bit under the well is very bad, the rolling element bears higher rotating speed and larger load, and if the tiny rock scraps broken by the cutting teeth or other tiny particle mediums in the drilling fluid invade into the contact gap between the rolling element and the rolling support body, the rolling element is quickly worn and out to lose efficacy due to inflexible rotation. Due to the presence of the sealing means, the working life of the rolling elements can be increased.

Preferably, springs, cushioning pads, hydraulic systems, or cushioning systems combining the above are provided between the rolling element support and the grooves on the support.

In the above scheme, due to the existence of the buffer system, the rolling bodies of the rolling elements roll on the rock surface, and meanwhile, the whole rolling elements of the rolling elements can also have a certain moving space relative to the support or the blade. The movement here refers to a movement in the depth direction of the groove in which the rolling element is mounted on the carrier. When the drill bit is impacted greatly, particularly when the drill bit is impacted from bottom hole rock along the rotation axis direction of the drill bit, the buffer system can absorb part of impact energy, has a certain buffer effect on the drill bit, and better plays a role in protecting cutting teeth.

Preferably, the rolling element support is a tensile body, and the tensile surface thereof may be cylindrical, polygonal, or elliptical.

According to the scheme, the rolling element supporting bodies are all common regular bodies in shape, so that the rolling element supporting bodies are simple in design and convenient to install and process.

Preferably, the drill bit is provided with movable roller cone cutting structures and/or cutter disc cutting structures.

In the above aspect, the other cutting structures include a fixed cutting structure and an unfixed cutting structure, the fixed cutting structure may be an impregnated cutting structure, and the unfixed cutting structure may be a cone cutting structure, a disc cutter cutting structure, an impact cutting structure, or a combination of at least two cutting structures therebetween. Different cutting structure combinations are selected according to different stratum conditions and drilling process parameters so as to enhance the adaptability of the drill bit in a specific stratum.

Advantageous effects

1. The drill bit can be provided with a larger supporting area and supporting point which are contacted with the rock at the bottom of the well, and the drilling stability of the drill bit is increased.

2. The rolling element is a non-cutting type structure, can share partial bit pressure applied to the cutting teeth of the drill bit, and limit excessive penetration in the cutting process of the PDC teeth, so that the stick-slip vibration of the drill bit is eliminated, the torque fluctuation of the drill bit is reduced, the premature failure of the cutting teeth is avoided, and the service life of the drill bit is prolonged.

3. The rolling elements change the conventional drill bit to be provided with a fixed cutting depth control element, namely, the sliding friction between the cutting depth control element and the underground stratum is changed into rolling friction, so that the torque of the drill bit is greatly reduced. In particular, in the steering drilling, the stability of the tool face in the orientation process is facilitated, and the orientation efficiency is improved.

4. When the support is in a bridge form, the strength of the blade can be enhanced. Particularly, when the outer bridge type support is positioned in the gage region, the self-righting capability of the drill bit can be enhanced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some examples of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic diagram of a low torque diamond bit suitable for hard formation drilling in accordance with the present invention.

Fig. 2 is a schematic view of a rolling element with spherical rolling bodies.

Fig. 3 is a schematic view of another rolling element with spherical rolling elements.

Fig. 4 is a schematic view of a rolling element with a cylindrical rolling body.

Fig. 5 is a schematic diagram of the mating of a cylindrical rolling element with an end cap.

Fig. 6 is a schematic view of a rolling element with a disc-shaped rolling body.

Fig. 7 is a schematic view of a plurality of disc-shaped rolling bodies.

Fig. 8 is a schematic view of another disc-shaped rolling body.

FIG. 9 is a schematic view of a rolling element as a cutting insert.

FIG. 10 is a schematic view of a rolling element as a milled cone.

Fig. 11 is a schematic view of a rolling element and a supporting body with balls therebetween.

Fig. 12 is a schematic view of a rolling element with a damping device and a seal.

Fig. 13 is a schematic view of a plurality of rolling elements on a rolling element.

FIG. 14 is a schematic view of a plurality of rolling elements on a support.

Fig. 15 is a schematic view of the connection between the rolling elements and the support.

Fig. 16 is a schematic view of the engagement of rolling elements with a sleeve.

Fig. 17 is a schematic view of a first rolling element to blind bore sleeve connection.

Fig. 18 is a schematic view of a second rolling element to blind bore sleeve connection.

Fig. 19 is a schematic view of a third rolling element to blind bore sleeve connection.

Fig. 20 is a schematic view of a rolling element to through-bore sleeve connection.

Figure 21 is a schematic view of a first ball structure having an axial movement and free rotation scheme.

Figure 22 is a schematic view of a second ball structure with an axial movement and free rotation scheme.

FIG. 23 is a schematic illustration of the composition of the crown profile curve and the angle between the crown profile curve and the rolling elements.

FIG. 24 is a schematic view of the crown profile versus the height of the rolling elements.

Fig. 25 is a schematic view of a rolling element with a shift shaft on a drill bit.

Fig. 26 is a general view of a drill bit with rolling elements mounted on separate carriers.

Fig. 27 is a top view of a drill bit with rolling elements mounted on separate carriers.

FIG. 28 is a schematic view of the rolling elements disposed in front of the blade.

Fig. 29 is a schematic view of the rolling elements disposed behind the blades.

FIG. 30 is a schematic view of a plurality of rolling elements mounted on individual carriers.

FIG. 31 is a schematic view of a holder as a suspended extension of the blade sidewall.

FIG. 32 is a schematic view of a holder as a blade sidewall extension.

Fig. 33 is a schematic view of a bridge structure of the support.

Fig. 34 is a schematic view of the support being an outer bridge type support.

FIG. 35 is a schematic diagram of a dam type stand.

Fig. 36 is a schematic view of a drill bit with an attached impact cutting structure.

Fig. 37 is a schematic view of a drill bit with a cutter cutting structure mounted thereon.

FIG. 38 is a schematic view of a drill bit with a cutter cutting structure and a cone cutting structure mounted thereon.

FIG. 39 is a schematic view of a drill bit with a cone cutting structure installed.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, based on the embodiments of the invention, which are apparent to those of ordinary skill in the art without inventive faculty, are intended to be within the scope of the invention. Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, based on the embodiments of the invention, which are apparent to those of ordinary skill in the art without inventive faculty, are intended to be within the scope of the invention.

The embodiment of the invention provides a drill bit. Referring to fig. 1, the drill bit comprises a drill bit body 1, blades or fixed cutting structures 2 extending from or fixed on the drill bit body, and a water hole or a nozzle 3, wherein cutting teeth 4 are arranged on the blades 2, and the cutting teeth 4 can be PDC teeth or impregnated teeth. The drill bit is further provided with rolling elements 5 consisting of rolling bodies 52 and rolling support bodies 51, the rolling elements 5 being arranged in corresponding seats or recesses of the blades 2.

The drill bit further comprises bit axis 1a, fixed cutter 41, cutter teeth 42, impact teeth 43, carrier axis 50, carrier housing 51, balls 52, base 511, end cap 512, bolt 54, seal ring 55, balls 56, cushioning device 57, spring cushioning device 571, hydraulic cushioning device 572, washer cushioning device 573, snap spring 58, bushing 59, universal ball set support 6, carrier 7, cover plate 71, cutter head 8, impact cutting structure 9, cutter head 10, crown curve 12, inner cone 120, crown 121, outer cone 122, shoulder 123, gage 124, normal 125.

The drill bit further comprises a bit axis about which the drill bit is rotatable during breaking of rock, whereby relative movement between the cutting teeth 4 on the blades 2 and the rock takes place, thereby cutting the rock. The broken rock is carried into the annulus by the drilling fluid through the junk slots.

As shown in fig. 2, the rolling element 5 is composed of a rolling body 52 and a supporting body 51; the support body 51 is composed of an end cap 512 and a base 511, the end cap 512 and the base 511 are fastened together by welding or bolts 54, and the rolling bodies 52 freely roll in the space formed between the end cap 512 and the base 511. Due to the complexity of the downhole operation, the rolling elements 52 may be made of impregnated structure, synthetic diamond, alloy steel, hard alloy, powder metallurgy material, metal composite material, or surface wear-resistant material, so that the rolling elements have certain wear resistance and impact resistance. The support body 51 is a stretching body, and the stretching section thereof may be cylindrical, polygonal, elliptical, preferably cylindrical.

As shown in fig.3, the rolling elements may also be composed of only rolling elements 52 and supporting elements 51. The support body 51 is divided into left and right parts, and the two parts are fixed together by welding.

The rolling elements 5 are arranged in recesses of the blade 2 and/or the abutment 7, in particular in the following ways.

As shown in figure 1, the rolling elements 5 are directly arranged on the blades 2 where the cutting teeth of the drill bit are positioned, so that the drill bit does not need to be specially designed, the tooth distributing space of the drill bit can be saved while the cutting structure of the drill bit is not changed, the processing difficulty of the drill bit can be reduced, and the manufacturing cost can be saved. In this configuration, there are several alternatives, namely, the rolling elements 5 are arranged in front of the cutting teeth (fig. 28) and the rolling elements 5 are arranged behind the cutting teeth (fig. 29), and combinations thereof.

The term "front" as used herein refers to the direction in which the cutting tooth rotates about the bit axis during normal drilling, i.e., the direction in which the working face of the cutting tooth faces, for the cutting tooth on a particular blade. But rather "back".

As shown in fig. 26, 27 and 30, the abutment 7 of the rolling element 5 is independent of the blade 2 on which the fixed cutting tooth is located, i.e. the blade is not provided with the cutting tooth 4, but only the rolling element 5. By adopting the structure, the support can be arranged larger, so that rolling elements with larger size or more rolling elements can be arranged, and the torsion reducing and shock absorbing effects are better.

The abutment 7 may also be an extension of the blade sidewall. The scheme of this structure is exemplified as follows.

With reference to fig. 32, the seats 7 of the rolling elements 5 are not connected to the bit body 1, but instead hang like cantilever beams extending forward and/or backward from the side walls of the blades 2, which are referred to in this patent as blade side wall hanging extensions. The support avoids the flow passage space for discharging drilling fluid and rock debris from the bottom of the well, and ensures the cleaning and cooling of the cutting teeth.

Referring to fig. 28 and 32, the holder 7 is a portion of the sidewall of the blade 2 extending forward and also connected to the bit body 1, and this holder form is referred to as a blade sidewall extension in this patent. The blade sidewall extension is also part of the blade where the cutting tooth is located. Due to the fact that the rolling element seat is connected with the drill bit body 1, the structure can be used for installing the rolling element 5 with larger size on the premise that the strength of the blade is not weakened, meanwhile, the strength of the seat 7 is improved, and the rolling element 5 can bear larger load impact force. The abutment 7 is similarly available in the form of an abutment extending rearwardly of the side wall of the blade 2 and extending both forwardly and rearwardly.

Further, the support 7 is connected to two adjacent blades.

That is, a blade connecting body connecting the two blades is provided between the adjacent blades, and the blade connecting body is used as the support 7 of the rolling element 5. Referring to fig. 33, the support 7 is suspended in the flow path between the two blades. The blade connector of this structure is referred to as a bridge type support structure in this patent because it has a shape similar to a bridge in road traffic. The bridge-type support structure can provide enough installation space for the rolling bodies 5 and reserve the flow passage space for discharging drilling fluid and rock debris while providing the rolling bodies 5 with larger sizes. The bridge type support structure can be arranged on the crown curve of the drill bit near the gage region, and can also be arranged on the crown and inner cone regions of the crown curve of the drill bit.

Another form of abutment 7, shown in fig. 34, is a bridge abutment structure disposed in the gage region of the drill bit. Because it is located outside the drill bit near the borehole wall, it is referred to as an outer bridge abutment in this patent. The outer bridge structure enables the gauge between two adjacent blades to be connected into a smooth whole, so that the full gauge of a local area of the drill bit is formed, the gauge area of the drill bit is increased, a good self-righting effect can be achieved, the stability of the drill bit is greatly improved, the whirling of the drill bit is reduced, and the service life of the drill bit is prolonged; in addition, for the PDC drill bit, the linear speed of the cutting teeth at the outer cone of the drill bit is higher than that of other positions, the cutting teeth at the outer cone are easy to be subjected to larger impact load to fail, meanwhile, the torque contribution of the cutting teeth at the outer cone to the drill bit is also higher than that of other positions, and the rolling bodies 5 are arranged at the outer cone, so that the increase amplitude of the drill bit torque caused by the penetration depth of the cutting teeth at the outer cone is greatly reduced, and the drill bit torque is stabilized.

In particular, with reference to fig. 34, an outer bridge abutment is provided between each two adjacent blades.

In steerable drilling, the drill bit is required to have a certain side cutting capacity. When the drill bit slides and drills into the well to make a deviation, under the action of a guiding tool or a bent screw rod, the cutting teeth on the outer side of the drill bit can be tightly attached to one side of the well wall to cut the well wall, but because a larger flow passage space exists between adjacent blades, the blades have discontinuity in the circumferential direction, namely the outer surface of the drill bit is not a complete cylindrical surface, so that the phenomenon that one blade transits to the next blade exists in the contact process of the cutting teeth on the outer cone of the drill bit and the gauge protection part with the well wall, and the cutting teeth are damaged due to transverse impact vibration generated on the drill bit. The outer bridge type support mode can increase the contact area between the gauge of the drill bit and the well wall, which is equivalent to providing more support points between the gauge of the drill bit and the well wall rock, increasing the cylindricity of the drill bit surface, enabling the transition of the blade to be more stable and the cutting process of the cutting teeth to be more stable.

Similar to the outer bridge construction, the bridge-type support provided with the rolling bodies 5 is arranged in the region of the drill bit away from the gage, such as in the crown and inner cone regions, and this construction is referred to as an inner bridge-type support in this patent. The form can form a certain buffering and damping effect on the cutting teeth in the core area, so that the coring phenomenon of the drill bit caused by the failure of the cutting teeth in the core area is relieved. The advantages of this form of stand-off are even more pronounced, especially in steerable drilling.

The embodiment of arranging the rolling elements 5 on the outer bridge type support and the inner bridge type support respectively can be easily obtained, and the scheme that the inner bridge structure and the outer bridge structure are simultaneously arranged on the drill bit and the rolling elements 5 are all arranged on the outer bridge and the inner bridge can be easily obtained, so that the coverage area of the rolling elements 5 on the drill bit is wider, and the torsion reducing and shock absorbing effects on the drill bit are stronger.

In another form of abutment, with reference to fig. 35, the abutment 7 of the rolling element 5 is connected to the front and rear sides of the adjacent blades and also to the bit body. This form of abutment is referred to herein as a dam abutment. Cutting teeth such as PDC teeth, hard alloy teeth, impregnated teeth and the like can be arranged on the dam type support, or wear-resistant materials are sprayed or welded on the surface.

Alternatively, the rolling bodies may be spherical, cylindrical, disc-shaped, roller-shaped, insert-shaped, and milling-shaped, as well as combinations thereof.

As shown in fig. 2 and 3, the rolling elements 52 are spherical rolling elements. The rolling bodies may be cylindrical in shape (fig. 4, 5) in addition to spherical rolling bodies; disc-shaped with double-sided support (fig. 6), on which saw-tooth grooves can be milled (fig. 8); a roller shape or a plurality of rollers with double-sided support (fig. 7); a cutting cone with double sided support (fig. 9) and a milling cone (fig. 10). Spherical rolling bodies are used as the optimal scheme of the patent.

The rolling elements 5 may be provided with sealing elements 55 (fig. 5, 11, 12, 13) to prevent external medium from entering the rolling elements 5. Steel balls 56 (fig. 11) may be provided in the rolling elements 5 to increase the flexibility and load-bearing capacity of the rolling elements 52 for rolling. A damping device 57 having a certain elasticity, such as a cushion, a spring, a hydraulic pressure, etc., may be provided between the rolling elements 52 of the rolling element 5 and the foundation 511.

The distribution density of the rolling elements 52 in the rolling elements 5 can be set according to different load-bearing requirements and the rolling elements 52 of different load-bearing capacities can be selected. Referring to fig. 13, a plurality of spherical rolling elements 52 are provided on the rolling elements 5.

Another rolling element, fig. 14, is a plurality of rolling elements 5 mounted on a module. The module is also regarded as a support 5. For ease of distinction, this module may be designated 6 and will be referred to as a support for ease of description.

The support body 6 and the support seat 7 are fixedly connected and movably connected. The fixed connection mode can be in the forms of welding, interference fit and the like. Referring to fig. 15, the support body and the support 7 are positioned by balls to form a rotatable movable connection.

A sleeve 59 (fig. 16) may be provided between the support body 6 and the abutment 7, the sleeve 59 having a higher wear resistance than the abutment 7. The sleeve 59 may be a blind sleeve or a through-hole sleeve. The sleeve 59 is secured in the recess of the support by welding or interference fit. The support body 6 and the shaft sleeve 59 are limited by the steel balls 56 (figure 17) or the snap springs (figure 18), but can freely rotate around the axis. Referring to fig. 19, a buffer device 57 such as a spring, a cushion pad, or the like is provided between the sleeve 59 and the support body 6.

As shown in fig. 20, the shaft sleeve 59 is a through hole, the inner hole of the shaft 59 is a stepped hole, the shaft sleeve 59 is fixedly connected to the support 7 in a welding or interference fit manner, the axial movement range of the support body 6 and the stepped hole is limited by the snap spring 58, and the buffer device 57 is arranged between the support body 6 and the shaft sleeve 59 or between the support body 6 and the support 7.

As shown in fig. 21, the support body 6 and the shaft sleeve 59 form a rotary connection, and the two are axially locked by balls or snap springs. The sleeve 59 has a multi-step shape, and a cover plate 71 is arranged between the sleeve and the support 7, and the cover plate 71 is connected with the support 7 through bolts 54. A spring 571 is connected between the sleeve 59 and the support 7 for cushioning. Further, a buffer gasket 573 may be provided between the sleeve 59 and the cover plate 71.

As shown in fig. 22, the support body 6 and the shaft sleeve 59 form a rotary connection, the two are axially locked by balls or snap springs, a certain space for containing hydraulic oil is arranged between the shaft sleeve 59 and the support 7, and the hydraulic oil space is connected with a one-way valve 572 of a hydraulic system for unidirectional in-out and flow of liquid. The rolling element 5 is reciprocated in the axial direction by vibration during operation, and when the space is reduced, the shaft sleeve 59 pushes hydraulic oil to flow out of the outlet check valve, and conversely, hydraulic oil flows in from the inlet check valve, and the axial vibration of the rolling element 5 is greatly reduced by the outflow and inflow of hydraulic oil. Further, a spring 71, or a buffer washer, may be provided between the sleeve 59 and the support 7.

Alternatively, as shown in FIG. 23, the support axis 50 may be at an angle in the range of 0-60 with respect to the normal reference line at the intersection of the fixed cutter outer envelope line 12. Further, the included angle of the two is 0 degrees.

Alternatively, as shown in FIG. 24, the relative height between the rolling element 5 and the cutting tooth of the drill bit is in the range of 0 mm.ltoreq.H.ltoreq.5 mm. Further, the relative height between the two is 0mm.

As shown in fig. 25, the axial distance S of the rolling elements 5 with respect to the center of the bit body is 0 to 5mm. It can be seen that the wheelbase S is zero if the axis 50 of the rolling element 6 intersects the bit axis 1 a. If the axis 50 of the support body 6 is moved in the horizontal direction by a distance S, rolling elements with a moving shaft are formed. The presence of the displacement moment S for the support body which is freely rotatable in the recess of the support 7 increases the rotation capacity of the support body 6 and thus the uniformity of the rotation of the rolling bodies 52 or the rolling elements 5 on the support body 6. Further, the displacement distance of the support body 6 relative to the center of the bit body is 0mm.

Alternatively, the bit has at least one other movable cutting structure in addition to the fixed diamond cutting structure.

Other movable structures may be the impact cutting structure 9 (fig. 36), the cutter cutting structure (fig. 37), the roller cone cutting structure (fig. 39), or at least two movable cutting structures, referring to the roller cone cutting structure and the cutter cutting structure in fig. 38.

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, and various modifications and variations may be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (9)

1. A low-torque diamond drill bit suitable for drilling in hard formations, comprising a drill bit body, blades extending from the drill bit body or fixed on the drill bit body, water holes or nozzles, and flow channels, wherein cutting teeth are arranged on the blades, and characterized in that: rolling elements are arranged on the blades, and at least one blade is only provided with rolling elements; or at least one blade has a support extending from the blade in front and/or behind, and the support is provided with rolling elements; the rolling elements are arranged in grooves of the blades or the support; the rolling elements are composed of rolling bodies and supporting bodies, and the rolling elements are spherical and can rotate freely; in the axial plane of the drill bit, the axis of the supporting body intersects with the outer envelope of the cutting teeth at a point, which is called the reference point, and an acute angle δ is formed between the normal reference line of the cutting teeth passing through the reference point and the axis of the supporting body, and the range of δ is 0°≤|δ|≤60°. 2. A low-torque diamond drill bit suitable for hard formation drilling according to claim 1, characterized in that the support is connected to two adjacent blades. 3. A low-torque diamond drill bit suitable for hard formation drilling according to claim 1, characterized in that the relative height range between the rolling element and the drill bit cutting teeth is 0mm≤|H|≤5mm. 4. A low-torque diamond drill bit suitable for hard formation drilling according to claim 1, characterized in that the rolling elements are arranged at different positions of the crown profile of the drill bit. 5. A low-torque diamond drill bit suitable for hard formation drilling according to claim 1, characterized in that the rolling element is composed of a rolling body and a supporting body, and the rolling body is spherical, cylindrical, disc-shaped, waist drum-shaped and/or a combination thereof. 6. A low-torque diamond drill bit suitable for hard formation drilling according to claim 1, characterized in that the rolling element is provided with a sealing device. 7. A low-torque diamond drill bit suitable for drilling in hard formations according to claim 1, characterized in that a spring, a buffer pad, a hydraulic system, or a buffer system composed of the above is arranged between the rolling element support body and the groove on the support. 8. A low-torque diamond drill bit suitable for hard formation drilling according to claim 7, characterized in that the rolling element support body is a stretching body, and its stretching surface is circular, polygonal, or elliptical. 9. A low-torque diamond drill bit suitable for hard formation drilling according to claim 1, characterized in that a movable cone cutting structure and/or disc cutting structure is installed on the drill bit.