Deflector-less multilateral system using a buoyant guide sub

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.

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.