RU2628363C2 - Method for balancing loads in bit with polycrystalline diamond equipment - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: according to method for balancing loads in a bit with polycrystalline diamond equipment having blades with PDC teeth fixed thereon and additional support elements for limiting the cutting depth, during the design process, the support elements are arranged on the blades in such a way that the maximum distance from the support elements to the bit axis L_max satisfies the inequality L_max<0.4⋅R, where R is the bit radius.

EFFECT: reduced energy consumption of drilling and increased durability of the bit equipment.

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Description

The invention relates to a method for designing weapons for drill bits with polycrystalline diamond elements (PDC).

A known method of balancing loads in a bit with polycrystalline diamond elements [1], adopted as an analogue.

The disadvantage of this method of balancing loads is that it is limited to balancing only the torque on the shaft of the hydraulic downhole motor due to the selection of the depth of cut of the rock with PDC cutters, which is ensured by the installation of additional supporting elements restricting the introduction of PDC cutters.

In this case, downhole reactions to PDC cutters and additional supporting elements create forces and moments relative to two coordinate axes perpendicular to the axis of the bit, resulting in unbalanced forces and moments relative to these axes, deflecting the bit when it rotates to the borehole wall, which leads to additional milling and an increase in the diameter of the well, deviation of the bit during drilling from a given design path, an increase in the wear of weapons, and, as a result, a decrease in the mechanical speed of drilling.

Another disadvantage of this method is a significant increase in the required torque due to friction during the interaction of additional supporting elements with the rock.

There is another way to balance the loads in the PDC bit [2], adopted as a prototype.

The disadvantage of this method of balancing loads is that part of the supporting elements is located at a considerable distance from the axis of the bit, which increases the required torque and, consequently, the energy consumption during drilling, as well as accelerated wear of the arms of the bit.

The technical result of the present invention is to reduce the energy consumption of drilling a bit with polycrystalline diamond elements and increase the durability of its weapons.

The technical result is achieved in that in a bit with polycrystalline diamond armament having blades with PDC cutters fixed on them and additional supporting elements to limit the depth of cut, PDC cutters and additional supporting elements are located on the blades in the design process so that the maximum distance from the thrust elements to the axis of the bit L _max satisfies the inequality

L _max <0.4⋅R,

where R is the radius of the bit.

In the proposed method of balancing the loads in the PDC bit, additional supporting elements (PDC cutters, surfaces of the blades deposited with hard alloy and (or) other supporting elements) are mounted on the blades so as to minimize the total moment relative to the axis of the bit and thereby the energy cost of drilling a well.

This is achieved by placing the supporting elements at a distance from the axis of the bit, less than 0.4 from its radius. In this case, the shoulder of the friction force arising during drilling is reduced, as well as the magnitude of the force, since the shoulder region of the blade located at a distance from the bit axis greater than 0.4R is the most loaded, as shown in FIG. 1 and 2 [3].

For example, if cutter No. 6 shown in FIG. 2 will have the same radius as tool 4, then only by reducing the force on the tool from 2250 to 1600 lbf will the torque be reduced by

.

.

Thus, the placement of the supporting elements of the PDC bit in the range from 0 to 0.4R allows to reduce the amount of torque required for drilling the well, i.e. energy intensity of drilling.

The results of field tests of samples of bits with the proposed method of placing support elements on the blades confirmed a decrease in the energy consumption of drilling with a drill with polycrystalline diamond elements and an increase in the durability of its weapons.

The list of drawings. According to accepted practice, the geometric parameters of the drawings are not to scale.

In FIG. 1 shows a PDC bit blade with supporting elements fixed thereto.

In FIG. 2 shows a graph of the force on the cutter versus its removal from the bit axis (cutter number). Here, a larger cutter number corresponds to a greater distance to the axis of the bit.

In FIG. 1 numbers indicate: 1 - PDC bit blade, 2 - supporting elements on the blade; the letter R denotes the radius of the bit.

Information sources

1. US patent No. 6298930 from 10.10.2001, class. E21B 10/46 "Drill bits with controlled tool loading and cutting depth."

2. RF patent No. 2498038 dated 04/10/2012, cl. E21B 10/43 "Method of balancing loads in a bit with polycrystalline diamond weapons."

3. Drill Bits Catalog. Baker Hughes, 2013.

Claims (3)

A method of balancing loads in a bit with polycrystalline diamond armament having blades with PDC teeth mounted on them and additional supporting elements to limit the depth of cut, characterized in that during the design process the supporting elements are located on the blades so that the maximum distance from the supporting elements to the axis bits L _max satisfy the inequality L _max <0.4⋅R, where R is the radius of the bit.

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