Rig types and basic drill string components. Part 1

Main ideas / concepts conveyed

• Purpose of drilling rigs: Drilling rigs bore holes into the earth, usually to find or produce oil and gas. They operate on land and offshore (both shallow and deep water).

• Rig size/depth ranges (land rigs):

  • Light duty: ~3,000–5,000 ft (≈1,000–1,500 m)
  • Medium duty: ~4,000–10,000 ft (≈1,200–3,000 m)
  • Heavy duty: ~12,000–16,000 ft (≈3,500–5,000 m)
  • Ultraheavy duty: ~18,000–25,000 ft or more (≈5,500–7,500 m or more)

• Six basic rig types (as grouped in the oil industry):

  1. Land rigs – drill on dry land; most common.
  2. Jackup rigs – offshore units with legs resting on the seafloor.
  3. Platform rigs – fixed offshore structures; do not move after installation.
  4. Submersible rigs – can submerge on the seafloor by flooding; can be towed after refloating.
  5. Semi-submersible rigs – floating units with pontoons/columns; partially submerge to a set depth.
  6. Drill ships – self-propelled offshore floating drilling units.

• General offshore-water-depth capabilities:

  • Jackup rigs: from a few meters/feet up to >400 ft (≈120 m) water depth (as stated).
  • Submersible rigs: designed for shallow water up to ~175 ft (~50 m) (as stated).
  • Semi-submersibles: capable of deep water, including >7,500 ft (>2,200 m) (as stated).

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Detailed breakdown of how rig types work (mechanisms and operating approach)

1. Land rigs

• Drill dry-land wells to varying depths depending on duty category.
• Transport options: moved by trucks, tractors, trailers, barges, helicopters, heavy rolling gear, skids, and (rarely) specialized air-pressurized equipment.
• Mobility note: light rigs are relatively easy to move; ultraheavy land rigs can be difficult to move.

2. Jackup rigs (offshore)

• Operate with:
  • Legs that support a deck/hull while positioned over the well site.
  • Leg bottoms resting on the seafloor.
• Workflow:
  • Towed to location with legs up.
  • Once crews position legs firmly on the seafloor, they adjust and level the deck and hull height.

3. Platform rigs (fixed offshore)

• Immobile after construction; companies drill multiple wells from the same platform.
• Tender-assisted option: a tender floats next to the pinned platform (platform is firmly fixed to seafloor).
• Many platforms do not use a tender due to their self-contained size.
• Examples mentioned:
  • Steel jacket
  • Quenson/“queson” type (as transcribed)
  • Concrete gravity type
• Deep-water challenge: structures must be built to yield to water and wind movement.
• Compliant platform types mentioned:
  • Guide tower
  • Tension leg

4. Submersible rigs

• During drilling:
  • Rig rests on the seafloor.
  • Workers flood compartments to submerge the rig.
• When moving:
  • Workers remove water from compartments so the rig floats and can be towed to the next site.
• Submersibles listed (as examples in the subtitles):
  • “posted barge submersible”
  • “bottle type submersible”
  • Arctic submersible

5. Semi-submersible rigs

• Definition: floating offshore drilling rig.
• Key structure:
  • Pontoons and columns
• During drilling:
  • Flooding pontoons causes the unit to partially submerge to a predetermined depth.
  • Drilling equipment is assembled on deck at the drill site.
• Positioning over the well:
  • Either anchor to the seafloor, or
  • Use thrusters and positioners to stay over the hole.
• Additional notes:
  • Wellhead and blowout preventers are mounted on the ocean floor.
  • A special hollow pipe called riser pipe connects the top of the blowout preventer.
  • Dynamic positioning may be used:
    • Thrusters controlled by an onboard computer.
• Example logistics:
  • Semi-submersible loaded on a special carrier for long moves.
  • For shorter moves: rig owner “tows” (as stated), or some units are self-moving (cut off in subtitles).

6. Drill ships

• Definition: self-propelled floating offshore drilling unit.
• Uses a subsea blowout control system similar to semi-submersibles (as stated).

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Rotary drilling rig basics (methodology + component relationships)

Overall purpose

• Rotary drilling rig equipment (surface + subsurface) aims to:
  • Place a drill bit at the bottom of the hole to drill/make the well.

Step-by-step process (as implied by the subtitles)

• Install the bit:
  • Rig crew screws the bit into a special pipe.
  • That pipe is the drill string.
• Lower the assembly:
  • Crew lowers the drill string and attached bit into the hole.
• Rotate the bit (rotary action):
  • Surface equipment rotates the bit unless rotation is provided by a mud motor.
  • Two rotation systems mentioned:
    • Top drive
    • Kelly + rotary table
• Apply drilling weight:
  • Equipment must force the bit’s cutters/teeth into the formation (by applying weight).
• Circulate drilling fluid:
  • Drilling mud circulates to carry drill cuttings away from the bit; otherwise the hole would clog.
• Transmit power to depth:
  • Rotary rigs transfer power from the surface downhole via the drill string.

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Top drive system (key components described)

How rotation is achieved

• Top drive rotates the drill string efficiently.
• It is described as:
  • Expensive but very efficient.
  • Allows crew to add drill pipe joints quickly and safely.
  • Compared with Kelly/rotary table, it reduces chance of the drill string getting stuck (as stated).

Component relationships and function (detailed)

• A powerful motor turns a drive shaft.
• The crew makes up/attaches the drill string to the drive shaft.
• The drive shaft turns the drill string and bit.
• The drill string passes through an opening in the rotary table:
  • The rotary table itself does not rotate (per subtitles).
• The top drive unit is suspended from the rig’s traveling block by a link system.

Mud circulation through the top drive

• Drilling mud enters the top drive through a gooseneck.
• A rotary hose (flexible line) conducts mud from the pumps to the top drive.

Safety/control element

• Built-in inside blowout preventer (IBOP) / safety valve:
  • Prevents fluid backflow up the drill string when the driller closes it.

Making/breaking connections

• Torque wrench assembly:
  • Used to make up and break out connect/disconnect the drill string.

Handling the drill string while moving

• Elevator:
  • Elevator links suspend it.
  • Crew latches the elevator around the drill string so the top drive can lift/lower the string.

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Kelly + rotary table system (key concepts introduced)

Components mentioned

• Kelly
• Kelly drive bushing
• Master bushing
• Rotary table

Kelly geometry and tradeoffs (as stated)

• Kelly can be:
  • Square (4 sides) or
  • Hexagonal (6 sides)
• Square Kellys: less expensive.
• Hex Kellys: stronger, so deep-hole rigs often use them.

How rotation works

• Crew makes up/attaches the Kelly to the top joint of the drill string.
• Example flow described:
  • A square Kelly moves through a square opening in the kelly drive bushing.
  • The kelly drive bushing mates with the master bushing.
  • The rotary table turns the master bushing → rotates the Kelly → rotates the entire drill string and bit.
• The subtitles end mid-description: “The Kelly moves down as the …” (incomplete).

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Speakers / sources featured

• No specific speakers or named sources are identified in the subtitles; content appears to be narrated/explanatory by the video’s creator or an unseen narrator.