# US 11,993,993 B2 · Deflector-less multilateral system using a buoyant guide sub > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,993,993 B2 - Document ID: US11993993B2 - Status: Granted - Kind: B2 - Application number: 17/674,418 - Filed: 2022-02-17 - Published: 2023-08-17 - Granted: 2024-05-28 - Earliest claimed: 2022-02-17 - Assignees: Halliburton Energy Services, Inc. - Applicants: Halliburton Energy Services, Inc. - Inventors: Morten Falnes; Angus Mackay Barron; Mark C. Glaser; Michael Linley Fripp - Web page: https://patentgrep.com/patent/US11993993B2 ## CPC - E21B 23/12: Tool diverters - E21B 41/0035: {Apparatus or methods for multilateral well technology, e.g. for the completion of or workover on wells with one or more lateral branches} - E21B 7/061: {the tool shaft advancing relative to a guide, e.g. a curved tube or a whipstock} - E21B: EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS ## Abstract Provided is a buoyant guide sub for use with a downhole oilfield conveyance. The buoyant guide sub, in one aspect, includes a hollow tubular structure, the hollow tubular structure including one or more tubular walls. The buoyant guide sub, according to at least one aspect, further includes a housing coupled to and slidable relative to the hollow tubular structure, the hollow tubular structure and the housing operable to form a pressurized chamber, the hollow tubular structure and housing having a combined mass per unit volume less than a specific gravity of 2. ## Claims ### Claim 1 A buoyant guide sub for use with a downhole oilfield conveyance, comprising: a hollow tubular structure, the hollow tubular structure including one or more tubular walls; and a housing coupled to and slidable relative to the hollow tubular structure, the hollow tubular structure and the housing operable to form a pressurized chamber, the hollow tubular structure and housing having a combined mass per unit volume less than a specific gravity of 2, wherein the housing includes a piercing device coupled thereto. the piercing device configured to pierce the hollow tubular structure when the housing slides relative to the hollow tubular structure. ### Claim 2 (depends on 1) The buoyant guide sub as recited in claim 1, further including one or more shear features temporarily fixing the housing relative to the hollow tubular structure to form the pressurized chamber. ### Claim 3 (depends on 2) The buoyant guide sub as recited in claim 2, further including one or more seals positioned between the housing and the hollow tubular structure to prevent fluids or gasses from entering or exiting the hollow tubular structure until the one or more shear features have sheared. ### Claim 4 (depends on 1) The buoyant guide sub as recited in claim 1, wherein the hollow tubular structure and housing have a combined mass per unit volume less than a specific gravity of 1.5. ### Claim 5 (depends on 1) The buoyant guide sub as recited in claim 1, wherein the hollow tubular structure and housing have a combined mass per unit volume less than a specific gravity of 1. ### Claim 6 A method, comprising: advancing an oilfield conveyance along a primary wellbore toward a multilateral junction having a high-side exit to a secondary wellbore, the oilfield conveyance having a buoyant guide sub positioned at a leading end thereof, the buoyant guide sub including: a hollow tubular structure, the hollow tubular structure including one or more tubular walls: and a housing coupled to and slidable relative to the hollow tubular structure, the hollow tubular structure and the housing operable to form a pressurized chamber, the hollow tubular structure and housing having a combined mass per unit volume less than a specific gravity of 2, wherein the housing includes a piercing device coupled thereto, the piercing device configured to pierce the hollow tubular structure when the housing slides relative to the hollow tubular structure; and using the buoyancy of the buoyant guide sub to bias the buoyant guide sub toward a high-side of the primary wellbore while moving the buoyant guide sub into the high-side exit to a downstream portion of the secondary wellbore. ### Claim 7 (depends on 6) The method of claim 6, further including: generating the buoyancy using a hollow tubular structure filled with a gas; and pressurizing the gas to offset a hydrostatic pressure external to the buoyant guide sub. ### Claim 8 (depends on 6) The method of claim 6, further including piercing an end wall of the buoyant guide sub after moving the buoyant guide sub across the high-side exit, to provide through-tube access for fluid or the oilfield conveyance into the secondary wellbore. ### Claim 9 (depends on 6) The method of claim 6, further including supplementing the buoyancy of the buoyant guide sub by urging the buoyant guide sub upwardly using a mechanical spring. ### Claim 10 (depends on 6) The method of claim 6, wherein the oilfield conveyance comprises a leg of a multi-bore junction assembly, and the buoyant guide sub guides the leg into the high- side exit. ### Claim 11 (depends on 10) The method of claim 10, wherein the leg is a secondary wellbore leg. ### Claim 12 (depends on 6) The method of claim 6, further including dissolving at least a portion of the buoyant guide sub after moving the buoyant guide sub into the high-side exit and to a downstream portion of the secondary wellbore. ### Claim 13 A well system, comprising: a primary wellbore; a secondary wellbore extending from a high-side of the primary wellbore, the primary wellbore and secondary wellbore forming a multilateral junction; and an oilfield conveyance having a buoyant guide sub positioned at a leading end thereof, the buoyant guide sub including: a hollow tubular structure, the hollow tubular structure including one or more tubular walls: and a housing coupled to and slidable relative to the hollow tubular structure, the hollow tubular structure and the housing operable to form a pressurized chamber, the hollow tubular structure and housing having a combined mass per unit volume less than a specific gravity of 2, wherein the housing includes a piercing device coupled thereto, the piercing device configured to pierce the hollow tubular structure when the housing slides relative to the hollow tubular structure. ### Claim 14 (depends on 13) The well system as recited in claim 13, further including one or more shear features temporarily fixing the housing relative to the hollow tubular structure to form the pressurized chamber. ### Claim 15 (depends on 14) The well system as recited in claim 14, further including one or more seals positioned between the housing and the hollow tubular structure to prevent fluids and/or gasses from entering and/or exiting the hollow tubular structure until the one or more shear features have sheared. ### Claim 16 (depends on 13) The well system as recited in claim 13, wherein the hollow tubular structure and housing have a combined mass per unit volume less than a specific gravity of 1.5. ### Claim 17 (depends on 13) The well system as recited in claim 13, wherein the hollow tubular structure and housing have a combined mass per unit volume less than a specific gravity of 1.