# US 10,480,250 B2 · Bore tube for a pressure compensation system in a roller cone drill bit

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- Number: US 10,480,250 B2
- Document ID: US10480250B2
- Status: Granted
- Kind: B2
- Application number: 15/548,122
- Filed: 2015-03-06
- Published: 2018-02-01
- Granted: 2019-11-19
- Earliest claimed: 2015-03-06
- Assignees: Halliburton Energy Services, Inc.
- Applicants: Halliburton Energy Services, Inc.
- Inventors: Robin Brian Milligan
- Web page: https://patentgrep.com/patent/US10480250B2

## CPC

- E21B 10/24: characterised by lubricating details (E21B10/23 takes precedence)
- E21B 10/25: characterised by sealing details
- E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS

## Abstract

The disclosure relates to a bore tube for a pressure compensation system in a roller cone drill bit. The bore tube includes a bit body having at least one support arm extending therefrom, a lubricant chamber in each support arm, a bore in each support arm extending from to the lubricant chamber to an exterior surface of each support arm, a tube in the bore of each support arm, and a floating bead in the tube and operable to move axially within the tube in response to a pressure of the environment surrounding the roller cone drill bit.

## Claims

### Claim 1

A roller cone drill bit comprising:
a bit body having at least one support arm extending therefrom;
a lubricant chamber in each support arm;
a bore in each support arm extending from to the lubricant chamber to an exterior surface of each support arm;
a tube in the bore of each support arm, the tube having an inner perimeter with a smooth surface texture;
a seal located between a wall of the bore and an outer perimeter of the tube to prevent a lubricant occupying a space between the wall of the bore and the outer perimeter of the tube from exiting the space; and
a floating bead in the tube and operable to move axially within the tube in response to a pressure of the environment surrounding the roller cone drill bit.

### Claim 2 (depends on 1)

The drill bit of claim 1, further comprising a retainer located between an end of the tube and the exterior surface of each support arm.

### Claim 3 (depends on 1)

The drill bit of claim 1, wherein an end of the tube is flared.

### Claim 4 (depends on 1)

The drill bit of claim 1, wherein the tube is manufactured from stainless steel.

### Claim 5 (depends on 1)

The drill bit of claim 1, wherein the tube extends substantially the length of the bore.

### Claim 6

A method for lubricant pressure relief comprising relieving a pressure differential between a lubricant in a lubricant chamber and a wellbore environment whenever a pressure of the lubricant and a pressure of the wellbore environment is substantially unequal, wherein the pressure compensation mechanism is in a roller cone drill bit including:
a bit body having at least one support arm extending therefrom;
the lubricant chamber in each support arm;
a bore in each support arm extending from to the lubricant chamber to an exterior surface of each support arm;
a tube in the bore of each support arm, the tube having an inner perimeter with a smooth surface texture;
a seal located between a wall of the bore and an outer perimeter of the tube to prevent a lubricant occupying a space between the wall of the bore and the outer perimeter of the tube from exiting the space; and
a floating bead in the tube and operable to move axially within the tube.

### Claim 7 (depends on 6)

The method of claim 6, wherein the roller cone drill bit further includes a retainer located between an end of the tube and the exterior surface of each support arm.

### Claim 8 (depends on 6)

The method of claim 6, wherein an end of the tube is flared.

### Claim 9 (depends on 6)

The method of claim 6, wherein the tube is manufactured from stainless steel.

### Claim 10 (depends on 6)

The method of claim 6, wherein the tube extends substantially the length of the bore.

### Claim 11

A drilling system comprising:
a drill string; and
a roller cone drill bit including:
a bit body having at least one support arm extending therefrom;
a lubricant chamber in each support arm;
a bore in each support arm extending from to the lubricant chamber to an exterior surface of each support arm;
a tube in the bore of each support arm, the tube having an inner perimeter with a smooth surface texture;
a seal located between a wall of the bore and an outer perimeter of the tube to prevent a lubricant occupying a space between the wall of the bore and the outer perimeter of the tube from exiting the space; and
a floating bead in the tube and operable to move axially within the tube in response to a pressure of the environment surrounding the roller cone drill bit.

### Claim 12 (depends on 11)

The drilling system of claim 11, wherein the roller cone drill bit further includes a retainer located between an end of the tube and the exterior surface of each support arm.

### Claim 13 (depends on 11)

The drilling system of claim 11, wherein an end of the tube is flared.

### Claim 14 (depends on 11)

The drilling system of claim 11, wherein the tube is manufactured from stainless steel.