Basic Hydraulics Training

Basic Hydraulics Training – Practice Exercises

Dynamic Pressure Management © Schlumberger 2014

Dynamic Pressure Management 1. INTRODUCTION The following document has been prepared to complement the material provided in the ‘Basic Hydraulics’ class that is part of the DPM Fundamentals School. Its intention is to provide the class with additional material to practice and solve basic hydraulic exercises that are usual in the drilling business, and especially in the MPD business. Students will find an MS Excel Worksheet that can be used to solve these exercises but are encouraged to solve them step-by-step in order to develop a thorough understanding of hydraulic calculations in wellbores. An answer key is provided at the end of this document to verify that results obtained during the process are correct.

2. ASSUMPTIONS



All wells are assumed to be vertical Fluids density is assumed to be remain constant regardless of pressure and temperature changes

3. EXERCISES 1. Calculate the hydrostatic pressure that results of a 10 000’ column of water (density = 8.34 ppg) 2. What is the mud density necessary to create a hydrostatic pressure of 4992psi in an 8 000’ well? 3. A well has been displaced from 5 000’ to surface with a kill mud weight of 15ppg. If the rest of the well (total depth = 11 000’) is filled with a mud density of 12ppg, calculate the bottom hole equivalent mud weight.

4. A well with a mud density of 12ppg is being used in a well whose bottom hole equivalent mud weight is 14ppg. The well depth is 15 000’ and the bit (point from where a kill mud weight can be pumped from) if at 8 000’. Calculate the kill mud weight necessary to balance the bottom hole EMW.

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Dynamic Pressure Management 5. An influx was taken in a well with the following conditions:
Well Depth = 18 000’
Mud Density = 14ppg
Shut-in Pressure = 1564psi Determine the influx height if the gas gradient is 0.1 psi/ft and the bottom hole equivalent mud weight is 15 ppg

6. An influx was taken in a well with the following conditions:
Well Depth = 20 000’
Mud Density = 15ppg Determine the Shut-in Pressure gas gradient is 0.1 psi/ft, the influx height is 1 103’ and the bottom hole equivalent mud weight is 14.5 ppg 7. Calculate the equivalent pore pressure in ppg (bottom hole equivalent mud weight) in a well that has been shut-in after an influx has entered the wellbore with the following information:
Well Depth = 10 000’
Mud Density = 12ppg
Shut-in Pressure = 1175psi
Influx Height = 1 250’
Gas gradient = 0.1 psi/ft

8. In a 20 000’ well, the target ECD being kept while drilling is 16.5ppg. If the mud density used is 16.0ppg and annular friction losses are 420psi, determine: a. If it is necessary to apply backpressure while drilling, and, if the answer is yes, determine its value. b. If it is necessary to apply backpressure during connections (static periods), and, if the answer is yes, determine its value.

9. In a 7 500’ well, the target ECD being kept while drilling is 15.5ppg. If the mud density used is 15.0ppg and annular friction losses are 300psi, determine: a. If it is necessary to apply backpressure while drilling, and, if the answer is yes, determine its value. b. If it is necessary to apply backpressure during connections (static periods), and, if the answer is yes, determine its value.

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Dynamic Pressure Management 10. In a 10 000’ well, the target ECD being kept while drilling is 15ppg. If the mud density used is 15ppg and annular friction losses are 100psi, determine: a. If it is necessary to apply backpressure while drilling, and, if the answer is yes, determine its value. b. If it is necessary to apply backpressure during connections (static periods), and, if the answer is yes, determine its value.

11. Determine the length of a pipe with an ID = 4.276” that could be filled with 17.76bbl of a mud.

12. Calculate how many barrels of a fluid are needed in order to fill up 210’ of a pipe with an ID = 3.5”

13. How many barrels will be necessary to fill up the annular space between a casing with an ID = 8.366” and a pipe with an OD = 5” if the well depth is 5 034’?

14. A cased well (depth = 20 000’) well with a casing ID = 8.336” and a pipe string composed entirely of 3.5” DP (ID = 3.111”) has been entirely displaced with a new mud. Determine the volume of mud necessary for this operation (remember that both the drill string and the annulus are filled up with this fluid)

15. A total of 988’ of a 5” DP (ID = 4.276”) has been run in a well closed-ended. Determine: a. The theoretical volume the pipe should have displaced based on the above information b. If 27.5bbl of added volume were measured at surface, can you conclude that there is a potential influx in the well? Why?

16. After POOH 488’ of a 5 ½” pipe (ID = 4.67”) with an open end, 3bbl of mud were necessary to fill up the well. Determine if based on this volume there may be an influx in the well. If the answer is yes, explain why.

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Dynamic Pressure Management 4. ANSWER KEY 1. Hydrostatic Pressure = 4337 psi 2. Mud density = 12ppg 3. Bottom Hole Equivalent Mud Weight = 13.4ppg 4. Kill Mud Weight = 15.8ppg 5. Influx Height = 1000ft 6. Shut-in Pressure (at surface) = 1241psi 7. Equivalent Pore Pressure = 13ppg 8. a. It is necessary to apply 100psi on surface while drilling to keep the ECD in the target value b. It is necessary to apply 520 on surface during connections to keep the ECD in the target value 9. a. It is not necessary to apply pressure on surface while drilling to keep the ECD in the target value b. It is necessary to apply 195psi on surface during connections to keep the ECD in the target value 10. As the target ECD is equal to the mud density, it is not necessary to apply pressure while drilling or during connections to keep the ECD in the target value (or above it in the case of the drilling condition) 11. Length = 1000ft 12. Volume = 2.5bbl 13. Volume = 220bbl 14. Volume = 1310bbl 15. a. Theoretical Volume = 24 bbl b. Yes, more volume than expected has been measured at surface (a portion of the volume in the well may be occupied by the influx)

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Dynamic Pressure Management 16. Yes. There may be an influx in the wellbore. The theoretical volume is 4bbl and the well was filled up with only 3bbl, indicating that portion of the volume in the well may be occupied by the influx.

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