Unit 2 - Rig Components Flashcards
What are the six major sub-systems on a drilling rig?
- power system - hoisting system - circulating system - rotary system - well control system - well monitoring system
Describe the components of a rotary drilling rig
How do rigs usually receive their electrical power?
There are diesel powered internal combustion engines that drive eletrical power generators
Which components on the drilling rig need electrical power supply ?
drawworks, rotary table and mud pumps
What uses the most electrical power on the drilling rig ?
the drawworks and the mud pumps
What is the task of a hoisting system?
to raise and lower drillstring and casing in and out of well
What is the drawworks?
A revolving drum around which the drilling line is spooled → controlled by the driller
Describe the components of a hoisting system!
How are crown block and travel block connected?
drilling line is threaded of sheaves at crown block and sheaves at travel block
Why do you need the hook attached to the travelling block?
To acutally suspend the drillstring
How do you call the set of clamps, which are connected to the travelling block? and what is there task?
Called the elevators → used when drillstring/casing is put in hole or pulled out from it
If one side of the drilling line is connected at the the drawworks, where is the other side connected ? and how do you call the other side?
It is connected at an anchor point and called the deadline
How do you call the part of the drilling line, that is spooled over the drawworks?
Fastline
How do you choose the correct tensile strength of the drilling line as well as the number of times, that it is reeved throught the travelling- and crown block?
It depends on the load, which also has to be supported by the hoisting system
How do you calculate the tensile load of the drilling line and deadline ?
Ff = W/ExN
Fd = W/N
Why do you need to include an efficiency factor in the calculation of Ff ?
Pulley system has always inefficiency → level of inefficiency is function of number of lines → more lines , more inefficiency
Why do you only need to include the efficiency factor for the calculation of the fastline and not the deadline?
Because the load on the deadline is a static load and will not be a function of the inefficiency therefore
What do you need to do if you want to increase the load that the hoisting system has to support ?
Either increase the number of lines reeved around the blocks or use a drilling line with a greater tensile strength
Where will the drilling line experience its most severe wear?
At point, where the rope passes over the top of the crown block sheaves and the end of the drilling line, where it constantly is spooled over the draw works drum
How do you maintain a drilling line?
Execute regular slip or slip and cut operations
What is a slipping operation?
- travelling block lowered to rick floor
- unclamping of dead line anchor
- threading some of reverse line through sheaves of travelling- and crown block onto drawworks drum
What is the problem with the slipping operation?
Can only be done 2-3 times before the drawworks drum is full → then you have to do a slip and cut operation
What is a slip- and cut operation?
- Lower travel block to drill floor
- dead line anchor is unclamped and line on drawworks is unwounded
- unwounded line is cut and thrown away
- Reverse line is threaded thorugh system onto drawworks drum
When experiences the drilling line the greatest amount of work ?
During round trips
What are criterias on how to select a suitable rig ?
- it needs to match the strength and capacity of the hoisting gear
- it needs to be able to withstand the climatic conditions
- it needs to have enough mobility for its application
What are the two main functions of drilling fluid?
- clean hole of cuttings made by the drillbit
- Apply hydrostatic pressure sufficient to prevent formation fluids from entering the borehole
Circulating system (graphic)
A drilling fluid consists of ?
water, clay, weighting material (Barite) and chemicals
What happens to the mud when it comes up the annulus?
Goes through flowline → solid removal equipment to remove cuttings → recirculation
What kind of mixing pumps are usually used for the mud?
Centrifugal pumps (high volume, low pressure)
How many slush pumps do you have at least at a rig?
At least 2
How would you connected 2 slush pumps in shallow depths?
Parallel to have high flow rates
How would you connect 2 flush pumps in deeper depths?
In series → to have high pressure and lower pump rates
What does it mean, when a pump is double acting?
Pump on the up-stroke and on the down stroke
(Duplex)
What does it mean, when a pump is single acting?
They only pump on an up stroke (Triplex)
What are the advantages of a triplex pump?
- lighter
- smoother discharge
- lower maintenance costs
Where is the discharge line of a mud pump connected to ?
to the standpipe
How are the standpipe and swivel connected?
Via the kelly hose
What are the advantages of using reciprocating positive displacement pumps?
- can pump fluids with high solid content
- wide range of pressures and flow rates
- reliable
- simple to operate, easy to maintain
Pump flowrate and pressure depend on ?
the sleevesize (liner), which is inside the cylinders of pump
The power consumption of a pumpe is a product of ?
Flow rate and the output pressure
The overall efficiency of a mud pump is a product of ?
Mechanical efficiency (Em) and volumetric efficiency (Ev)
What is one stroke?
One complete pump revolution?
How much is the volume output of a duplex pump with a spm of 20?
80 cylinder volumes per minute
Why is the discharge of a triplex pump smoother than the one of a duplex pump?
Because it is always an equal volume that is discharged
How come that triplex pumps are usually used offshore?
They are usually lighter and more compact
Can triplex pumps or duplex pumps deliver a highter pressure?
Triplex pumps, because they can use higher pump speeds
What are the 3 functions of a swivel?
- support the weight on drill string
- allows string to rotate
- allows mud to be pumped while string rotates
What is the function of the kelly?
- 40’ long joint
- outer hexagonal cross sectioin
- transmits rotation from rotary table to drillstring
Parts of the rotary system?
Function of kelly saver sub ?
prevent excessive wear of threads of kelly connection (due to make- up and breakout of kelly)
What are the kelly cocks?
valves at both ends of kelly → prevent backflow from well
What is the function of the master bushing?
to protect the roatry table on rig floor
How is the torque from the rotary table transmitted to kelly ?
through the kelly bushing
What are slips used for ?
to hold the top of the drillpipe when it is screwed or unscrewed
What is a stand?
3 joints of drillpipe together
What is a top drive?
A power swivel connected to travelling block - 1000 hp electric motor
Advantages of a top drive system?
- 90’ stands can be added to string → elimination of 2 connections → saves time → more efficiency
- When tripping out of hole → power swivel can easily be stabbed into string → circulation + string rotation when pulling out of hole if necessary (stuck pipe)
- when tripping into hole → power swivel can be connected to allow any bridges to be drilled out without having to pick up kelly
Disadvantages of top drive system?
- Increase in top side weight on rig
- Electric and hydraulic control lines must run up inside the derrick
What is the function of a well control system?
Prevent uncontrolled flow of formation fluids from wellbore
Well control systems are designed to?
- detect a kick
- close-in the well at surface
- remove formation fluid, which has flowed into well
- make well safe
Which parameters needs to driller to check to see if they change (well monitoring)?
- WOB
- RPM
- pump rate
- pump pressure
- gas content of mud
