IWCF Well Control Practice Test Welcome to the Enform IWCF practice test. You will need a formula sheet and a calculator to complete this test (go to www.iwcf.org click on syllabuses and print a copy of the S.I. Formula sheet). Read the questions carefully and select the most appropriate answer. At the end of the test, you can self assess your knowledge with the attached answer key. You should be able to obtain a grade of 80% or better to be prepared for IWCF Program.
Surface Stack Questions 1 – 25
Subsea Stack Questions 26 - 33
1. Normal formation pressure is generally a) 9.81 kPa/m b) 10.52 kPa/m c) 15.4 kPa/m d) 22.6 kPa/m
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2. While circulating out a kick regardless of the kill method, the pressure to control constant is the a) Casing pressure b) Drill pipe pressure c) Bottom hole pressure d) All of the above
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3. The formation leak-off pressure is determined by a) Adding the applied surface pressure and hydrostatic pressure b) Subtracting the applied surface pressure from the hydrostatic pressure c) Adding the SIDPP and hydrostatic pressure d) Adding the SICP and hydrostatic pressure
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4. Casing is set at 3000 m and LOT is performed with a fluid density of 1400 kg/m3. The leak off pressure is established at 9000 kPa. a) What is the leak off pressure at the shoe? b) What is the MAASP if the fluid density is raised to 1450 kg/m3? 5. A well is being drilled at 3000 m using a 1350 kg/m3 mud, prior to tripping out of hole, 4 m3 of 1650 kg/m3 slug is pumped in. Given the drill pipe capacity of 0.0093 m3/m, what is: a) Height of slug in the drill string? b) What is the differential pressure between slug and mud column? c) Top of fluid in the drill string after the slug is settled in? d) How much mud should flow to the trip tank once the Kelly or top drive is removed?
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6. A well at 3200 m with 1375 kg/m3 mud is being shut in, SIDPP of 2500 kPa and SICP of 3500 kPa. Given that RSPP was 4500 kPa at 35 SPM, calculate: a) The ICP and FCP using the driller’s method b) The ICP and FCP using driller’s method for 40 SPM
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7. A heavy mud pill is circulated in the well? At what moment will the bottom hole pressure start to increase? a) As soon as the pill starts to be displaced into the drill string b) Once all the pill has been displaced into the annulus c) Once the pill starts to be displaced into the annulus
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8. Casing is being run into the hole with a conventional float valve. Due to a problem with the fill up line, the casing was not filled. Twelve 12 m joints have been run into the hole. If the float valve and collar suddenly fail, how would this affect bottom hole pressure? 1 340 mm 91 kg/m casing Casing capacity – 0.079363 m3/m Mud weight = 1400 kg/m3 Annular capacity = 0.064534 m3/m a) Bottom hole pressure decreases by 505 kPa b) Bottom hole pressure decreases by 1090 kPa c) Bottom hole pressure decreases by 1820 Kpa 9. A vertical well is shut in after a kick. The pressure readings are as follows: 1
Shut in drill pipe pressure (SIDPP) = 4680 kPa Shut in casing pressure (SICP) = 6150 kPa What is the reason for the difference in the two pressure readings? a) The influx is in the drill pipe b) The influx has a lower density than the drilling fluid c) The influx has a higher density than the drilling fluid
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10. A kicking well has been shut in. If a salt water influx was being circulated out using the Driller’s method, when would the casing pressure be at its maximum? a) At initial shut in b) When the top of the influx reaches the casing shoe c) When the influx is at the surface
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11. While drilling, a gas kick is taken and the well is shut in 1
SICP = 0 kPa SIDPP = 3620 kPa There is no flow from the annulus. What is the probable cause? a) The well has been swabbed in b) The hole has packed off around the bottom hole assembly c) The formation at the casing shoe has fractured 12. You have one inside BOP with an NC50 (114 mm) lower connection on your rig but the drill string consists of 127 mm HWDP, and 203 mm drill collars. Which one of the following crossovers would you have on the drill floor in case of a kick while tripping? a) NC50 (114 mm) pin x 168 mm reg. pin b) NC50 (114 mm) box x 194 mm reg. pin c) NC50 (114 mm) box x 168 mm reg. pin
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13. An influx is being circulated out using the driller’s method and using 7500 kPa at 30 spm. The operator increased the pump speed to 35 spm but holds casing pressure constant. What happens to BOTTOM HOLE PRESSURE? a) Remains approximately the same b) Decreases c) Increases
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14. For each of the following statements choose whether it relates to the Driller’s Method or the Wait and Weight method. Circle your answer a) Before pumping kill mud influx is circulated out DRILLER or WAIT AND WEIGHT b) Pump kill mud as the influx is pumped up the annulus DRILLER or WAIT AND WEIGHT c) Maintain Drill Pipe pressure constant for entire circulation DRILLER or WAIT AND WEIGHT d) Minimize pressures created in the annulus do to gas expansion DRILLER and WAIT AND WEIGHT
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15. At what point during a well kill would you expect the highest pressure at the shoe, while circulating out a gas kick? a) When the top of the gas reaches the shoe b) At initial shut-in c) When top of gas reached surface d) Either (a) or (b) could be right depending on hole geometry
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16. Which three of the following conditions are essential for the calculation of an accurate formation strength at the shoe? a) Accurate stroke counter b) Accurate pressure gauge c) Exact mud density d) Exact vertical depth of casing shoe e) Accurate hole volume f) Installation of retrievable packer below wellhead
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17. For a Soft Shut-in, the choke manifold will most likely be set up while drilling as follows; HCR
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AUTO CHOKE
POORBOY DEGASSER VALVE
a)
Open
Closed
Closed
b)
Open
Open
Closed
c)
Closed
Open
Open
d)
Closed
Closed
Open
18. You notice zero returns on your flow rate indicator. You pull up, shut down the pumps and inspect the hole, the mud cannot be seen. What would be your first action? a) Pump with lower SPM and mix lost circulation material b) Drill blind c) Close the well in d) Start to fill the annulus with fluid
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19. Of all the following warning signs, which two signs would leave little room for doubt that the well is kicking? a) Flow line temperature increase b) Increased rotary torque c) Flow rate increase d) Decreased drill string weight e) Pit volume gain f) Increase rate of penetration
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For questions 20 and 21 please refer to the above picture 20. Would it be good drilling practice to circulate and kill the well with the lower set of 127 mm rams closed, when the drill string is in the hole? a) Yes b) No
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21. Can the inner choke valve be repaired if the well is shut in with the blind/shear rams with no drill string in the hole? a) Yes b) No
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22. In the above diagram a 37.85 litre accumulator bottle is pre-charged with nitrogen to 6895 kPa (a). The triplex pump will then charge the accumulator to 20,685 kPa maximum pressure (b). The accumulator is used and allowed to drop to a minimum pressure of 8275 kPa as read on the main accumulator gauge (c).
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a) The volume of gas in the accumulator at 20,685 kPa (Figure b) b) The volume of gas in the accumulator at 8275 kPa (Figure c) c) The volume of usable fluid between the range of 20,685 to 8275 kPa (Ignore temperature and compressibility) 23. You are drilling ahead and your BOP control system reads as follows (Drillers Remote Panel)
Select 2 answers a) Everything is OK b) There is a leak in the hydraulic system c) There is a malfunction in the pressure transducer assembly d) There is a malfunction in the hydraulic regulators
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24. Under what circumstances would a “cup-type” tester be used in preference to a “test plug” when testing a BOP stack a) There is no difference, they are interchangeable b) When you require to test entire casing head, outlets and casing to well head seals c) To test stack without applying excess pressure to wellhead and casing
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25. Complete the attached Driller’s Method Step One illustration based on the following data: Well Depth: Mud Density: Overkill: RSPP SIDPP SICP
1,527 m 1,140 kg/m3 1,400 kPa 4,000 kPa @ 50 spm 900 kPa 2,000 kPa
Driller’s Method Step One
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Subsea Stack Questions 26. Which two of the following statements are good operating practice in top hole that has a risk of bearing formations?
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a) b) c) d) e)
Pump out of the hole on trips Use a high mud weight to create maximum overbalance Drill a pilot hole of 216 mm diameter or less Maintain high rate of penetration to ensure mud viscosity level is as high as possible Regularly pump fresh water pill to clean cuttings from hole
27. In a vertical 216 mm hole at 4049 m depth with 1350 kg/m3 mud, and 244.5 mm casing shoe at 3345 m with following drill-string: Average length = 28 m.
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Drill Collar HWDP DP
159 OD & 73 ID mm 127 OD & 76.2 mm 127 OD & 108.61 mm
Length 228.3 m Length 56.8 m Cap 0.00046m3/m Disp 0.0098m3/m Cap 0.0093m3/m Disp 0.0040m3/m
Given the capacity of the riser is 0.03801m3/m calculate: a) Fluid level drop for pulling 10 stands dry without filling the hole b) Fluid level drop for pulling 10 stands wet without filling the hole c) Hydrostatic reduction for (a) & (b) 28. A drilling unit with 28 m air gap is operating in 875 m water depth using 1365 kg/m3 mud at drilling depth of 4265 m 2
Given sea water density is 1050 kg/m3, calculate: a) Hydrostatic pressure reduction in riser disconnect condition b) Riser margin at total depth 29. While drilling a well on a semi submersible drilling rig, what three factors may affect the accuracy of drilling fluid flow readings (flo-sho) and drilling fluid volume readings (PVT)? a) Vessel heave, crane operations, rig pitch and roll b) Water depth, number of generators on line, riser tension c) Vessel heave, crane operations, riser tension d) Water depth, rig pitch and roll, number of generators on line
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31. With a 20,685 surface accumulator and normal pre-charge of 6895kPa with a final kPa remaining pressure of 8275kPa, if a portion of the accumulator fluid is stored in accumulator bottles on the subsea stack, the hydrostatic pressure of the seawater must be compensated for when calculating N2 pre-charge a) In 200 m of water having a density of 1050 kg/m3, what will the maximum pressure of the subsea accumulator be when it is completely charged?
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b) What is the pre-charge pressure?
32. A 444.5 mm hole is being drilled below the 762 mm conductor. Given the following data:
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From rig floor to sea level Water depth Sea water gradient 762 mm conductor set
18 m 168 m 10 kPa/m 350 m (from rig floor)
From previous wells drilled, the formation fracture gradient beneath the sea bed is estimated to be 13.1 kPa/m. What is the theoretical maximum mud weight that can be used, with returns back to the rig floor?
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33. The above drawing (no. 2a) shows a semi-submersible with a kick being circulated out. The gas bubble is just entering the choke line. The well is being held overbalance. 3
Total depth (RKB) Height of kick in casing Assume gas gradient to be Oil mud weight (before kick) Kill mud weight Pressure loss up annulus Pressure loss choke line
4572 m 215 m 2.26 kPa/m 1440 kg/m3 1500 kg/m3 350 kPa 1400 kPa
a) What is the circulating bottom hole pressure? b) Later (drawing no. 2b) gas fills the choke line. What is the choke pressure that must be maintained to keep the same bottom hole circulating pressure? For this purpose assume that 350 kPa annular pressure loss and 350 kPa pressure loss up the gas filled choke line. c) How will it be necessary to adjust the choke for this? i) Reduce choke size ii) Increase choke size iii) Leave choke setting steady
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