38 Questions
What is the primary advantage of drillships compared to semisubmersibles?
Less costly unless dynamically positioned
What is the purpose of the central turret in some drillships?
To rotate the ship and face incoming waves
What is the main limitation of using drillships in offshore drilling?
Severe weather conditions
What is the purpose of the Mud Circulating System in a rotary drilling rig?
To circulate drilling fluid
What is the primary function of the Rig Power System in a rotary drilling rig?
To provide power to the hoisting and circulating systems
What type of engines are typically used as prime movers in a rotary drilling rig?
Diesel-electric engines
What is the primary function of the Well Control System in a rotary drilling rig?
To control the well pressure
What is the typical location of the diesel engines in a rotary drilling rig?
On the ground in back of the rig
What is the primary purpose of the substructure in a drilling rig?
To raise the elevation of the derrick floor to accommodate the BOP stack
What is the typical working pressure range for blowout preventers?
3,000 to 15,000 psi
What is the primary function of the choke manifold?
To direct flow from the well to various equipment
Where is the control panel for the choke manifold located?
On the drill floor
What is the purpose of the choke line?
To connect the BOP stack to the choke manifold
In the scenario described, what is the length of the casing string occupied by the blown-out fluid?
3,000 ft
What is the reservoir pressure of the gas-bearing zone in the scenario?
10,000 psi
What is the density of the drilling fluid in the scenario?
80 lb/cu.ft
What is the purpose of special marine equipment when drilling from a floating vessel?
To hold the vessel on location over the borehole and compensate for wave action
What is the sequence of drilling a well?
Drill 26” hole, set 20” casing, cement 20” casing
What is the purpose of cementing the casing?
To hold the casing in place
What is the purpose of running electric logs?
To obtain detailed information about the formation
What is the purpose of drilling a 17-1/2” hole?
To set a 20” casing
What is the primary function of a set of clamps on a drilling rig?
To grip a stand, or column, of casing, tubing, drill pipe, or sucker rods
What is the purpose of setting a 13-3/8” casing?
To provide additional support to the well
What is the purpose of a catwalk on a drilling rig?
To lift pipe to the derrick floor by the catline or by an air hoist
What is the primary function of a pipe rack on a drilling rig?
To provide a horizontal support for tubular goods
What is the Rotating System used for on a drilling rig?
To wrap around a joint of a pipe and pull to start screwing two joints together
What is the primary function of a drill collar?
To put weight on the bottom of the drillstring to control drilling and to prevent the drillpipe from kinking and breaking
What is the typical length of a drill collar?
31 ft
What is the purpose of a cathead on a drilling rig?
To serve as a spool-shaped attachment on a winch for hoisting and pulling
What is the purpose of a pipe ramp on a drilling rig?
To serve as an angled ramp for dragging drill pipe up to the drilling platform
What is the term for the pipe pulled three joints at a time?
Stands
Where does the bottom of the stand rest?
On the drill floor
What is the purpose of a bit breaker in the rotary table?
To grip the bit
What is the formula for cost per foot of drilled section?
C = B + R*T + T∖ + t
What is the term for the process of changing the bit and running the pipe back into the hole?
Tripping in
What is the name of the working platform of the derrickman?
Monkey board
What is the unit of measurement for the length of the section drilled?
Feet
What is the purpose of the formula 𝐂 = 𝐅/(𝐁+𝐑 𝐓+𝐓∖+𝐭)?
To calculate the cost per foot of drilled section
Study Notes
Drillship
- A type of floating vessel used in offshore drilling
- Less costly than semisubmersibles unless designed to be positioned dynamically
- Can operate in water depths up to 13,000 ft
- Some drillships have rig equipment and anchoring system mounted on a central turret, allowing the ship to rotate and face incoming waves
Rotary Drilling Rigs
- All rotary rigs have the same basic drilling equipment
- Main component parts of a rotary drilling rig:
- Rig Power System
- Hoisting System
- Rotary System
- Mud Circulating System
- Well Control System
- Well Monitoring System
- Special Marine Equipment
Rig Power System
- Prime movers are diesel engines that supply power to the rig
- Power is used primarily for hoisting and circulating systems, and to a lesser degree for rotating system, rig lights, and other motors
Elevators and Pipe Racks
- Elevators: a set of clamps that grip a stand of casing, tubing, drill pipe, or sucker rods
- Pipe racks: a horizontal support for tubular goods
Rotating System
- Drillstring consists of drillpipe, heavyweight drillpipe, and drill collars
- Drill collars are made of heat-treated alloy steel and are 31 ft long
- Two to ten drill collars are often used
- Drillpipe is stored horizontally on the pipe rack located on the ground next to the front of the rig
Types of Drilling Bits
- Milled (steel) tooth roller cone bits
- Insert tooth roller cone bits
- Roller cone types
- Fixed cutter (head) bits
Bit Selection
- Cost per foot = (bit cost + operating cost) / (length of section drilled)
- Cost per foot is affected by bit cost, operating cost, and length of section drilled
Drillstring Design
- Important factors to consider when designing a drillstring: weight, strength, and durability
- Drillstring must be able to withstand the forces and stresses encountered during drilling
Blowout Preventers (BOPS)
- Working pressures range from 3,000 to 15,000 psi
- Substructure is a steel framework that raises the elevation of the derrick floor to accommodate the BOP stack below it
- Choke manifold is a series of lines, automatic valves, gauges, and chokes on the ground next to the drilling rig
Special Marine Equipment
- Required for drilling from a floating vessel
- Special equipment is needed to hold the vessel on location over the borehole and to compensate for vertical, lateral, and tilting movements caused by wave action against the vessel
This quiz covers the features and capabilities of drillships, a type of floating vessel used in offshore drilling. It discusses their cost and operation in deep water.
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