Tricone bit special for reverse circulation drilling

Abstract

The invention belongs to the technical field of roller bits, and particularly relates to a special tricone bit for reverse circulation drilling, which comprises a bit leg, a central water outlet hole is formed in the middle of the bit leg, and a central nozzle is mounted at the lower end of the central water outlet hole. According to hydraulic analysis, a specific water hole outline is designed, alloy nozzles with different sizes, large inlet openings and small outlet openings can be matched according to stratums, so that mud has better trafficability, and more power is provided during upward reversing.

Description

Technical Field

[0001] The invention belongs to the technical field of roller drill bits, and in particular relates to a three-roller drill bit special for reverse circulation drilling. Background Art

[0002] The current drilling methods are mainly divided into positive circulation drilling and reverse circulation drilling. During the drilling process, a drill pipe is required, and a drill bit is arranged at one end of the drill pipe. During the positive circulation drilling process, mud is pumped from the mud pool into the inner cavity of the drill pipe by a mud pump, and then transported from the inner cavity of the drill pipe to the drill bit, and continuously transported into the borehole through the water hole of the drill bit, and then discharged from the annulus between the well wall and the drill pipe. At the same time, the rock cuttings generated during the drilling process are discharged from the annulus to the ground together with the mud; while the circulation method of the mud in reverse circulation drilling is just the opposite. The mud is transported from the annulus to the borehole by a mud pump, and then compressed air or a mud pump is used to suck the mud and rock cuttings into the inner cavity of the drill pipe through the water hole of the drill bit, and then pumped out from the inner cavity of the drill pipe to the ground.

[0003] Among them, the drill bit of positive circulation drilling has very strict requirements on the relative position of the water hole and the blade. The general design is that each blade corresponds to a water hole, which results in a small effective diameter of the water hole on the limited drill bit end face of the positive circulation drilling drill bit. At present, there is no special drill bit for reverse circulation drilling. During reverse circulation drilling, only the drill bit of positive circulation drilling can be used for drilling. However, during the reverse circulation drilling process, the mud and the cuttings generated during the drilling process are sucked into the drill pipe through the water hole on the drill bit. Since the water hole on the drill bit is small, during the reverse circulation drilling process, the mud and cuttings are easy to block the water hole, resulting in low drilling efficiency and drilling failure. Summary of the invention

[0004] The purpose of the present invention is to provide a three-cone drill bit specially used for reverse circulation drilling, so as to solve the problems existing in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: a three-cone drill bit specially used for reverse circulation drilling, comprising a tooth palm, a central water outlet hole is provided in the middle of the tooth palm, and a central nozzle is installed at the lower end of the central water outlet hole.

[0006] Preferably, the central nozzle is trumpet-shaped, and the diameter of the lower opening is larger than the diameter of the upper opening.

[0007] Preferably, the central nozzle is embedded in the central water outlet by means of interference fit.

[0008] Another scheme of the utility model is: a three-cone drill bit specially used for reverse circulation drilling, comprising a tooth palm, a central water outlet hole is arranged in the middle of the tooth palm, the lower part of the central water outlet hole is trumpet-shaped, and the diameter of the lower opening is larger than the diameter of the upper opening.

[0009] The beneficial effects of the present invention are as follows: the present invention designs a unique water hole profile based on hydraulic analysis, and can also match alloy nozzles of different sizes according to the stratum, with a large inlet and a small outlet, so that the mud has better passability and is more powerful when it is reversed. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a schematic diagram of one embodiment of the present invention;

[0011] Figure 2 It is a schematic diagram of another embodiment of the present invention. DETAILED DESCRIPTION

[0012] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0013] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0014] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect", "connect", "fixed connection" and "fixed connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0015] The specific implementation of the present invention is described in detail below with reference to the accompanying drawings and preferred embodiments.

[0016] like Figure 1 and Figure 2As shown, a three-cone drill bit specially used for reverse circulation drilling includes a tooth palm 1, a central water outlet hole 2 is provided in the middle of the tooth palm, and a central nozzle 3 is installed at the lower end of the central water outlet hole. Specifically, the central nozzle is trumpet-shaped, and the diameter of the lower opening is larger than the diameter of the upper opening. For a three-cone drill bit of small size or without machining allowance, a through hole is machined at the center position of the three-cone drill bit, and then a trumpet-shaped alloy nozzle is welded from the bottom of the through hole. The three-cone drill bit specially designed according to the present invention for reverse circulation drilling is conducive to the structure of mud passing through the water hole.

[0017] Furthermore, the central nozzle is embedded in the central water outlet through interference fit, so that the mud has better passability and more power when it is reversed.

[0018] Another scheme of the utility model is: a three-cone drill bit specially used for reverse circulation drilling, comprising a tooth palm 1, a central water outlet hole 2 is arranged in the middle of the tooth palm, the lower part of the central water outlet hole is trumpet-shaped, and the diameter of the lower opening is larger than the diameter of the upper opening. A three-cone drill bit with a large size or a processing allowance is processed into a trumpet-shaped curved water hole at the position of the central water hole. A large mouth enters and a small mouth exits. The mud has better permeability and is more powerful when reversed upward.

[0019] It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention, and these improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A three-cone drill bit specially used for reverse circulation drilling, comprising a cone palm, characterized in that: A central water outlet hole is arranged in the middle of the tooth palm, and a central nozzle is installed at the lower end of the central water outlet hole.

2. The three-cone drill bit for reverse circulation drilling according to claim 1, characterized in that: The central nozzle is trumpet-shaped, and the diameter of the lower opening is larger than the diameter of the upper opening.

3. The three-cone drill bit for reverse circulation drilling according to claim 2, characterized in that: The central nozzle is embedded in the central water outlet hole by means of interference fit.

4. A three-cone drill bit specially used for reverse circulation drilling, comprising a cone palm, characterized in that: A central water outlet hole is arranged in the middle of the tooth palm, the lower part of the central water outlet hole is trumpet-shaped, and the diameter of the lower opening is greater than the diameter of the upper opening.

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