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IWCF Level 2 Drilling study materials
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IWCF Level 2 Drilling practice questions

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Question 1Drilling Well Control

On a land rig, what is the primary purpose of the blowout preventer (BOP) stack?

  1. To increase the drilling fluid density while drilling ahead
  2. To seal the wellbore and control formation pressure when the well is shut in Correct answer.
  3. To rotate the drill string during normal drilling operations
  4. To separate drilled cuttings from the returning mud

Explanation

The BOP stack is a pressure-control barrier installed at surface; it closes around or across the wellbore to seal it and hold back formation pressure. It is not a drilling or solids-control device, and it cannot change mud weight.

Question 2Drilling Well Control

Which pressure is measured at the surface on the drill pipe with the well shut in and the pumps stopped?

  1. Slow circulating pressure (SCR)
  2. Equivalent circulating density (ECD)
  3. Shut-in drill pipe pressure (SIDPP) Correct answer.
  4. Shut-in casing pressure (SICP)

Explanation

SIDPP is read on the drill pipe gauge after the well is shut in and pumps are off, and it reflects the difference between formation pressure and the hydrostatic pressure of the mud column in the drill string. SICP is read on the casing gauge, while ECD and SCR involve circulation.

Question 3Drilling Well Control

A well is shut in and stabilised. SIDPP is 400 psi and SICP is 650 psi. What does the higher casing pressure most directly indicate?

  1. The drill pipe gauge is faulty and should be ignored
  2. The formation pressure is exactly 250 psi higher than the mud hydrostatic
  3. The annulus contains additional pressure contribution, such as trapped gas or a lighter fluid column Correct answer.
  4. The mud pumps are still running at a low rate

Explanation

When SIDPP and SICP differ, the annulus is carrying an extra pressure component beyond the drill string hydrostatic, commonly gas that has migrated or an influx with lower density. The difference of 250 psi is not the formation pressure itself.

Question 4Drilling Well Control

What is the correct first action when a positive kick indicator (flow with pumps off) is observed?

  1. Shut the well in using the hard shut-in procedure Correct answer.
  2. Continue drilling and monitor the pit level
  3. Reduce the mud weight to lower the ECD
  4. Increase the pump rate to circulate the influx out

Explanation

A flow with the pumps off is a primary kick indicator, and the well must be shut in promptly to stop further influx and allow pressures to be recorded. Continuing operations or circulating before shut-in allows more formation fluid to enter.

Question 5Drilling Well Control

Which of these is a recognized warning sign of a kick while drilling ahead?

  1. An increase in drilling rate (penetration rate) with a corresponding pit gain Correct answer.
  2. A steady pump pressure at constant rate
  3. A rise in mud weight returning at the flowline
  4. A gradual decrease in the active pit volume

Explanation

A drilling break, often seen as a sudden penetration rate increase, can signal entering a higher-pressure permeable zone; if it is followed by a pit gain the well is taking a kick. Pit loss, stable pressure and heavier returns are not kick indicators.

Question 6Drilling Well Control

What does the term 'formation pressure' mean in well control?

  1. The pressure of the fluids contained within the pore spaces of the formation Correct answer.
  2. The pressure required to break the rock at the casing shoe
  3. The pressure generated by the mud pumps at the standpipe
  4. The pressure exerted by the mud column on the bottom of the hole

Explanation

Formation (pore) pressure is the pressure of fluids in the rock's pore spaces and is what the mud hydrostatic must balance. Bottom-hole mud pressure and pump pressure are drilling-side pressures, not formation pressure.

Question 7Drilling Well Control

A mud column of 10,000 ft true vertical depth with a density of 10 ppg produces approximately what hydrostatic pressure?

  1. 5,200 psi Correct answer.
  2. 4,000 psi
  3. 3,000 psi
  4. 6,500 psi

Explanation

Hydrostatic pressure equals 0.052 × mud weight (ppg) × true vertical depth (ft). Here 0.052 × 10 × 10,000 gives about 5,200 psi. Using measured depth instead of true vertical depth would be incorrect.

Question 8Drilling Well Control

Why is true vertical depth (TVD) used rather than measured depth (MD) when calculating hydrostatic pressure?

  1. Hydrostatic pressure depends on the vertical height of the fluid column Correct answer.
  2. TVD accounts for the density of the formation rock
  3. Measured depth is always smaller than true vertical depth
  4. MD cannot be measured in deviated wells

Explanation

Hydrostatic pressure is created by the vertical height of the fluid column, so TVD is the correct input in the 0.052 formula. In a deviated well MD exceeds TVD, and using MD would overstate the pressure.

Question 9Drilling Well Control

What is the purpose of the slow circulating rate (SCR) pressure recorded during a well control drill?

  1. To set the maximum allowable mud weight
  2. To provide a reference pump pressure for calculating circulating pressures during kill operations Correct answer.
  3. To determine the fracture gradient at the casing shoe
  4. To measure the formation pressure directly

Explanation

SCR is recorded at a selected slow pump rate so that later pump pressures during the kill can be calculated from it. It is a reference circulation pressure, not a direct measure of formation or fracture pressure.

Question 10Drilling Well Control

Which statement best describes the 'driller's method' of well control?

  1. Shut in and wait for the influx to dissipate before resuming drilling
  2. Increase the pump rate to maximum while holding casing pressure constant
  3. Circulate the influx out with the original mud weight, then kill the well with weighted mud in a second circulation Correct answer.
  4. Weight up the mud to kill weight, then circulate the influx out in a single circulation

Explanation

In the driller's method the well is first circulated with the existing mud to remove the influx, then the mud is weighted and circulated to bring the well under control. The wait-and-weight method instead weights up first and kills in one circulation.

Question 11Drilling Well Control

During a kill operation, what is the purpose of holding casing pressure constant while bringing the pump up to kill rate?

  1. To allow gas to expand freely at surface
  2. To protect the casing from collapse
  3. To keep bottom-hole pressure at or slightly above formation pressure as circulating friction develops Correct answer.
  4. To reduce the mud weight required

Explanation

As pump rate increases, circulating friction adds to bottom-hole pressure; holding casing pressure steady compensates so bottom-hole pressure stays at the required value. This prevents both further influx and excessive pressure on the formation.

Question 12Drilling Well Control

What does the term 'kill weight mud' refer to?

  1. The mud density used during normal drilling ahead
  2. The mud density that balances formation pressure with no additional overbalance from friction Correct answer.
  3. The density at which the shale shakers operate efficiently
  4. The density that guarantees the casing shoe will not fracture

Explanation

Kill weight mud is calculated so its hydrostatic pressure equals formation pressure, using SIDPP and current mud weight. It is a static balance value and does not itself guarantee the shoe will not fracture.

Question 13Drilling Well Control

SIDPP is 300 psi, current mud weight is 11.0 ppg, and true vertical depth is 8,000 ft. What is the approximate kill weight mud?

  1. 12.5 ppg
  2. 11.0 ppg
  3. 11.7 ppg Correct answer.
  4. 10.3 ppg

Explanation

Kill weight equals current mud weight plus SIDPP divided by (0.052 × TVD). Here 300 divided by (0.052 × 8,000) is about 0.72 ppg, giving roughly 11.7 ppg.

Question 14Drilling Well Control

What does a leak-off test (LOT) primarily determine?

  1. The formation pore pressure at total depth
  2. The pressure at which the formation at the casing shoe begins to take fluid Correct answer.
  3. The rate at which the mud pumps deliver fluid
  4. The density of the drilling fluid in the active pit

Explanation

A leak-off test pressurises the well below the casing shoe until the formation starts to accept fluid, giving the fracture or leak-off pressure. It is used to set maximum mud weight and is not a measure of pore pressure at depth.

Question 15Drilling Well Control

Why is a formation integrity test (FIT) often preferred over a leak-off test on some wells?

  1. It confirms the formation can withstand a planned pressure without deliberately fracturing it Correct answer.
  2. It determines the mud weight required to kill the well
  3. It directly measures the formation pore pressure
  4. It replaces the need for a BOP stack

Explanation

A FIT pressurises to a predetermined value to confirm the shoe can hold the planned pressure, stopping before the formation actually fractures. A leak-off test continues until leak-off is observed, which is more damaging.

Question 16Drilling Well Control

What is the main function of the annular preventer in a BOP stack?

  1. To seal around a variety of drill string sizes and shapes, including the kelly Correct answer.
  2. To seal only on a specific pipe diameter with a fixed ram
  3. To regulate the mud return flow at the flowline
  4. To shear the drill pipe in an emergency

Explanation

The annular preventer uses a flexible element to close around irregular shapes and a range of pipe sizes, so it can seal on the kelly, drill pipe or tools. Ram preventers are size-specific, and shearing is done by blind or shear rams.

Question 17Drilling Well Control

Which BOP component is designed to close and seal the wellbore when no drill pipe is present?

  1. Annular preventer
  2. Choke manifold
  3. Pipe rams
  4. Blind rams Correct answer.

Explanation

Blind rams close across an open hole with no pipe in the wellbore, sealing the well completely. Pipe rams close around pipe and the annular seals around pipe or tools, while the choke manifold controls flow downstream.

Question 18Drilling Well Control

What is the purpose of a choke manifold in well control?

  1. To provide a backup for the rotary table
  2. To measure the density of the returning mud
  3. To control the release of pressure from the well while circulating out an influx Correct answer.
  4. To increase the mud weight before circulation

Explanation

The choke manifold contains adjustable chokes and valves that let the crew hold back pressure while circulating, controlling casing pressure and bottom-hole pressure. It does not change mud weight or measure density.

Question 19Drilling Well Control

What is 'kick tolerance' in well planning?

  1. The time allowed to shut the well in after a kick is detected
  2. The pressure rating of the annular preventer
  3. The maximum pump rate the choke can handle
  4. The maximum influx volume that can be safely circulated out without fracturing the formation at the shoe Correct answer.

Explanation

Kick tolerance expresses how large an influx the well can take and still be circulated out using kill weight mud without exceeding fracture pressure at the casing shoe. It is a pressure and volume limit, not a time or equipment rating.

Question 20Drilling Well Control

Which condition describes an 'underbalanced' well?

  1. The mud hydrostatic pressure is less than the formation pore pressure Correct answer.
  2. The well is shut in with the pumps running
  3. The mud hydrostatic pressure is greater than the formation fracture pressure
  4. The mud hydrostatic pressure exactly equals the formation pore pressure

Explanation

An underbalanced well has bottom-hole pressure below formation pore pressure, so formation fluid can enter the wellbore. Overbalance is the reverse, and exceeding fracture pressure risks losses rather than influx.

Question 21Drilling Well Control

What does 'MAASP' (maximum allowable annular surface pressure) represent?

  1. The maximum surface pressure that can be held on the annulus without exceeding fracture pressure at the shoe Correct answer.
  2. The maximum pressure the drill pipe can withstand before yielding
  3. The maximum pressure the mud pumps can deliver
  4. The maximum rate at which the choke can be opened

Explanation

MAASP is the surface pressure limit on the annulus, calculated from the fracture pressure at the shoe minus the annulus hydrostatic. Exceeding it risks breaking down the formation at the shoe.

Question 22Drilling Well Control

During a kill, gas in the annulus is migrating toward surface with the well shut in. What happens to surface pressure if no action is taken?

  1. Casing pressure rises as the gas expands and displaces mud Correct answer.
  2. Casing pressure remains unchanged regardless of gas movement
  3. Casing pressure falls steadily as gas moves upward
  4. Casing pressure drops to zero once the gas reaches the BOP

Explanation

Gas migrating upward without expansion room at surface causes surface pressure to rise, because it carries its pressure with it and displaces mud from the annulus. The correct response is to bleed mud or circulate to allow controlled expansion.

Question 23Drilling Well Control

Why must the drill string be kept full of mud when tripping out of the hole?

  1. To cool the drill bit more effectively
  2. To increase the weight on the bit
  3. To prevent the mud level dropping and reducing hydrostatic pressure in the well Correct answer.
  4. To speed up the tripping operation

Explanation

Pulling pipe removes steel volume from the hole, so the mud level falls unless it is replaced; the reduced hydrostatic column can allow an influx. Keeping the hole full maintains bottom-hole pressure.

Question 24Drilling Well Control

What is 'swabbing' during a trip?

  1. The loss of mud to a permeable formation while circulating
  2. The separation of gas from mud at the surface
  3. A reduction in bottom-hole pressure caused by pulling pipe, which can allow formation fluid to enter Correct answer.
  4. The increase in pressure caused by running pipe into the hole

Explanation

Swabbing occurs when pulling pipe creates a suction effect that lowers bottom-hole pressure and can draw formation fluid into the well. The opposite effect, surging, happens when running pipe in.

Question 25Drilling Well Control

A driller observes that pump pressure has dropped and pit volume has increased while drilling. Which interpretation is most appropriate?

  1. A possible kick or washout; the well should be checked and shut in if flow is confirmed Correct answer.
  2. Normal behaviour that requires no action
  3. Evidence that the choke is fully closed
  4. A sign that mud weight should be reduced

Explanation

A pump pressure drop with a pit gain can indicate a washout in the string, a nozzle problem, or an influx, and must be investigated with a flow check. If flow continues with pumps off, the well is shut in.

Question 26Drilling Well Control

On a well control worksheet, what does the abbreviation SIDPP represent?

  1. Static inflow drill pipe pressure
  2. Surface indicated drill pipe pressure
  3. Slow-in circulating pressure
  4. Shut-in drill pipe pressure Correct answer.

Explanation

SIDPP stands for shut-in drill pipe pressure, the stabilised standpipe reading taken with the well closed in and the pumps off. It is used to calculate kill mud weight and to track bottomhole pressure during a kill.

Question 27Drilling Well Control

Which surface reading is used together with SIDPP to calculate the initial circulating pressure for a kill?

  1. The pressure recorded while the bit is off bottom
  2. The pressure at which the casing shoe breaks down
  3. The rated working pressure of the BOP stack
  4. The slow circulating rate pressure for the chosen kill rate Correct answer.

Explanation

Initial circulating pressure is the slow circulating rate pressure plus SIDPP, so the SCR pressure for the selected kill rate must be known. This ensures bottomhole pressure stays at the required value once the pumps are running.

Question 28Drilling Well Control

What is the primary purpose of a kick?

  1. To allow formation fluid to enter the wellbore when bottomhole pressure is less than formation pressure Correct answer.
  2. To remove cuttings from the annulus
  3. To test the closing function of the BOP stack
  4. To deliberately reduce mud weight while drilling ahead

Explanation

An influx occurs when formation pressure exceeds the pressure exerted by the mud column, allowing formation fluid to flow into the wellbore. It is an unintended event that must be detected and controlled quickly.

Question 29Drilling Well Control

Which drilling parameter increase is a classic early warning of a kick while drilling?

  1. Increase in rotary torque with no change in weight on bit
  2. Increase in pit volume with pumps running at constant rate Correct answer.
  3. Decrease in rate of penetration
  4. Decrease in mud temperature at the flowline

Explanation

A gain in pit volume while the pumps are running at a steady rate indicates formation fluid is entering the well. It is one of the most reliable indicators and should trigger an immediate flow check.

Question 30Drilling Well Control

What does the term 'shut-in casing pressure' (SICP) measure?

  1. The pressure rating of the casing head
  2. The pressure lost to friction in the surface lines
  3. The pressure required to open the choke
  4. The pressure trapped in the annulus with the well closed in and pumps off Correct answer.

Explanation

SICP is the stabilised annular pressure read with the BOP closed and the pumps stopped. It reflects the combined effect of the influx and the mud column on the annulus.

Question 31Drilling Well Control

Which action should the crew take first when a flow check confirms the well is flowing with the pumps off?

  1. Close the BOP and record shut-in pressures Correct answer.
  2. Continue drilling and monitor the pit volume
  3. Reduce mud weight to lower bottomhole pressure
  4. Increase the pump rate to circulate the influx out

Explanation

The well must be closed in promptly to stop further influx and allow stabilised shut-in pressures to be recorded. Those pressures are the basis for all subsequent kill calculations.

Question 32Drilling Well Control

What is the function of the choke in a well control operation?

  1. To isolate the drill pipe from the annulus
  2. To measure the density of the returning mud
  3. To increase the pump rate during a kill
  4. To control the rate at which fluid leaves the well while maintaining pressure on the annulus Correct answer.

Explanation

The choke restricts the return flow so that casing pressure can be held at the required value while the influx is circulated out. Adjusting the choke is how the driller controls annular pressure.

Question 33Drilling Well Control

Which factor determines the hydrostatic pressure exerted by a mud column at a given depth?

  1. The viscosity of the mud
  2. The gel strength of the mud
  3. The annular clearance around the drill pipe
  4. The mud density and the true vertical depth Correct answer.

Explanation

Hydrostatic pressure depends only on fluid density and true vertical depth, following the relationship pressure equals density times depth times a constant. Viscosity, gel strength and annular geometry do not change hydrostatic pressure.

Question 34Drilling Well Control

A well is shut in with SIDPP of 400 psi and SICP of 650 psi. What does the difference between these two readings most directly indicate?

  1. The formation fracture pressure at the shoe
  2. The friction loss in the drill string
  3. The weight of the influx is heavier than the mud
  4. The pressure contributed by the influx column in the annulus Correct answer.

Explanation

SICP exceeds SIDPP because the annulus contains the influx, which is lighter than the mud it displaced. The difference reflects the pressure that the influx column fails to provide compared with mud.

Question 35Drilling Well Control

Why is the choke opened slightly while bringing the pump up to kill rate at the start of a kill?

  1. To allow for the increasing friction pressure in the drill string so that casing pressure falls by the corresponding amount Correct answer.
  2. To increase the rate at which the influx enters the wellbore
  3. To reduce the mud weight being pumped down the string
  4. To test whether the choke manifold is plugged

Explanation

As pump rate rises, friction in the string adds to bottomhole pressure, so casing pressure must be reduced by the equivalent amount to keep bottomhole pressure constant. The choke is opened progressively to achieve this.

Question 36Drilling Well Control

What is the 'final circulating pressure' in a kill operation?

  1. The pressure required to break circulation after a trip
  2. The maximum pressure the choke manifold can withstand
  3. The standpipe pressure once kill weight mud fills the entire drill string Correct answer.
  4. The pressure at which the pump is stopped at the end of the kill

Explanation

Final circulating pressure is reached when kill mud has displaced all the original mud in the string, leaving only the friction component at the chosen kill rate. It is lower than the initial circulating pressure.

Question 37Drilling Well Control

A driller notes the pump pressure has fallen and the pit level has risen while the pump rate is unchanged. What is the most appropriate immediate response?

  1. Reduce the mud weight to relieve the annulus
  2. Increase the pump rate to clear the annulus
  3. Continue drilling and record the readings for the morning report
  4. Stop the pumps, carry out a flow check, and shut the well in if flow continues Correct answer.

Explanation

A pressure drop with a simultaneous pit gain indicates an influx is entering the well, often called a kick while drilling. Stopping and flow checking confirms the influx before closing in and recording pressures.

Question 38Drilling Well Control

What is meant by 'bottomhole pressure' during a shut-in period?

  1. Only the hydrostatic pressure of the mud column
  2. The pressure exerted by the BOP rams on the drill pipe
  3. The pressure measured at the standpipe with the pumps running
  4. The sum of hydrostatic pressure from the mud column and any surface pressure applied to the annulus Correct answer.

Explanation

With the well shut in, bottomhole pressure equals the hydrostatic head of the mud plus the surface pressure trapped in the well. This balance against formation pressure is what keeps the well static.

Question 39Drilling Well Control

Why is a low pump rate usually chosen for circulating out a kick?

  1. To keep friction pressure low so that pressures remain manageable and below formation fracture limits Correct answer.
  2. To allow the influx to settle at the bottom of the hole
  3. To increase the pressure on the formation at the shoe
  4. To reduce the density of the returning mud

Explanation

A low kill rate keeps circulating friction small, so the extra pressure applied to the annulus stays within the formation's fracture strength. It also gives the choke operator more time to react.

Question 40Drilling Well Control

Which statement correctly describes the wait-and-weight method?

  1. The influx is circulated out first with the original mud, then the well is weighted
  2. The well is shut in and weighted up before circulation begins, then kill mud is pumped in one continuous operation Correct answer.
  3. The choke is kept fully open throughout the operation
  4. The pump is stopped whenever surface pressure rises

Explanation

In the wait-and-weight method the well is held shut in while mud weight is increased, then kill mud is pumped while pressure is controlled on the choke. This differs from the driller's method, which circulates out the influx first.

Question 41Drilling Well Control

What is the significance of the 'slow circulating rate pressure' recorded on a well control sheet?

  1. It records the pressure needed to circulate at a chosen low rate and is used to calculate circulating pressures during a kill Correct answer.
  2. It records the maximum pressure the formation can withstand before breaking down
  3. It records the pressure at which the BOP was last tested
  4. It records the pressure the choke manifold can safely contain

Explanation

The SCR pressure is measured at a low, fixed pump rate and represents the friction component of the circulating system. It is added to shut-in pressures to derive initial and final circulating pressures for the kill.

Question 42Drilling Well Control

During a kill, the choke operator maintains casing pressure on the drill pipe gauge schedule. Why is the drill pipe pressure gauge the primary control reference once pumping has started?

  1. It is the only gauge that can be read from the drill floor
  2. It directly reflects bottomhole pressure when friction and mud hydrostatics are accounted for Correct answer.
  3. It always reads higher than the casing gauge
  4. It shows the pressure rating of the drill string

Explanation

Once circulating, drill pipe pressure responds directly to changes in bottomhole pressure, so following the calculated schedule keeps the well balanced. The casing gauge is used mainly for monitoring and as a backup.

Question 43Drilling Well Control

What does the term 'influx' refer to in well control?

  1. Formation fluid that has entered the wellbore Correct answer.
  2. Cuttings returning over the shale shaker
  3. Water used to mix new mud at surface
  4. Mud lost to a permeable formation

Explanation

An influx is formation fluid, such as gas, oil or water, that has flowed into the wellbore because formation pressure exceeded the mud column pressure. It is the material that must be circulated out under control.

Question 44Drilling Well Control

A well has SIDPP of 500 psi at 9,000 ft TVD with 12.0 ppg mud. Which additional information is required to calculate the kill mud weight?

  1. The annular volume and the pump output
  2. The true vertical depth and the current mud weight Correct answer.
  3. The casing shoe depth and the mud viscosity
  4. The measured depth and the bit size

Explanation

Kill mud weight is derived from SIDPP, current mud weight and true vertical depth using the pressure gradient relationship. Measured depth, bit size, annular volume and viscosity do not enter the calculation.

Question 45Drilling Well Control

What is the main purpose of circulating out a kick at a constant bottomhole pressure?

  1. To test the pressure rating of the choke manifold
  2. To increase the rate of penetration after the kill
  3. To prevent further influx while avoiding formation fracture during the operation Correct answer.
  4. To reduce the volume of mud in the pits

Explanation

Holding bottomhole pressure constant, slightly above formation pressure, stops additional influx while staying below the fracture limit. This is the central principle behind all kill methods.

Question 46Drilling Well Control

Which condition would most likely reduce bottomhole pressure and allow an influx to enter the wellbore?

  1. Pulling pipe too fast so the mud level in the hole drops Correct answer.
  2. Keeping the hole full while tripping out
  3. Circulating at the recorded slow rate with the well balanced
  4. Maintaining mud weight above formation pressure

Explanation

Pulling pipe fast lowers the fluid level in the hole and reduces the hydrostatic head, which can allow formation fluid to enter. Filling the hole on trips is the standard remedy.

Question 47Drilling Well Control

During a kill, the drill pipe pressure is being held on the calculated schedule while kill mud is pumped down the string. What happens to drill pipe pressure as kill mud fills the string?

  1. It decreases gradually from initial to final circulating pressure Correct answer.
  2. It increases steadily until the pump is stopped
  3. It stays exactly the same throughout
  4. It drops to zero as soon as kill mud reaches the bit

Explanation

As heavier mud displaces the original mud in the drill string, the hydrostatic pressure in the string increases, so less standpipe pressure is needed to hold bottomhole pressure. The pressure therefore falls along the schedule to the final circulating value.

Question 48Drilling Well Control

A gas influx is being circulated up the annulus with the choke held to maintain constant bottomhole pressure. As the gas approaches surface, what must the choke operator do?

  1. Open the choke progressively to keep bottomhole pressure constant as the gas expands Correct answer.
  2. Stop the pump and allow the gas to vent through the bell nipple
  3. Close the choke progressively to prevent the gas from expanding
  4. Keep the choke at a fixed position regardless of pressure changes

Explanation

Gas expands as it rises and displaces mud, so annular pressure would rise if the choke were left unchanged. Opening the choke in a controlled way maintains constant bottomhole pressure while allowing the gas to expand.

Question 49Drilling Well Control

Why is the casing shoe pressure monitored closely during a kill?

  1. It is the point where the drill string is most likely to part
  2. It is the weakest point in the open hole and must not exceed the formation fracture pressure Correct answer.
  3. It is the location of the highest mud velocity in the annulus
  4. It is where the BOP is connected to the wellhead

Explanation

The shoe is usually the shallowest and weakest exposed formation, so exceeding its fracture pressure can cause losses and loss of well control. Monitoring shoe pressure keeps the operation within safe limits.

Question 50Drilling Well Control

A well is shut in and pressures have stabilised. If the influx is gas and the well is left shut in for a long period, what is the most likely consequence?

  1. The mud weight will increase automatically
  2. Casing pressure will drop to zero
  3. Surface pressures will fall as the gas dissolves into the mud
  4. Surface pressures will rise as the gas migrates upward through the mud Correct answer.

Explanation

Gas migrates upward through the mud column when the well is shut in, and because it cannot expand it carries its pressure to surface. This causes both drill pipe and casing pressures to increase over time.