SPE Drilling Engineering Principles 2 — Questions and Answers
Question 1: What is the primary purpose of a drill stem test (DST) in petroleum engineering?
- To measure the weight of the drill string
- To evaluate reservoir pressure, permeability, and fluid type before completing the well (Correct answer)
- To test the tensile strength of drill pipe
- To measure the rate of penetration
Correct answer: To evaluate reservoir pressure, permeability, and fluid type before completing the well
A DST evaluates formation fluid characteristics, reservoir pressure, and permeability to determine whether a well is commercially viable.
Question 2: In directional drilling, what does the term 'dogleg severity' (DLS) measure?
- The total depth of the wellbore
- The rate of change in wellbore inclination and azimuth per 100 feet (Correct answer)
- The weight applied to the drill bit
- The torque on the drill string
Correct answer: The rate of change in wellbore inclination and azimuth per 100 feet
Dogleg severity measures the rate of change in wellbore direction (both inclination and azimuth) per 100 ft, expressed in degrees per 100 ft.
Question 3: Which drilling fluid property describes its ability to suspend cuttings when circulation is stopped?
- Viscosity
- Fluid loss
- Gel strength (Correct answer)
- Density
Correct answer: Gel strength
Gel strength measures the thixotropic properties of drilling fluid that allow it to suspend cuttings and weighting materials when pumps are off.
Question 4: What is the function of a float valve (check valve) installed in the drill string?
- To regulate pump pressure
- To prevent backflow of formation fluids up through the drill pipe (Correct answer)
- To measure formation temperature
- To increase drilling fluid density
Correct answer: To prevent backflow of formation fluids up through the drill pipe
A float valve prevents wellbore fluids and gases from flowing back up into the drill string, helping to control kicks and maintain well control.
Question 5: The equivalent circulating density (ECD) is higher than the static mud weight because:
- Cuttings are removed from the mud
- Annular friction pressure losses add to the hydrostatic pressure (Correct answer)
- The pump pressure decreases downhole
- Temperature reduces mud density
Correct answer: Annular friction pressure losses add to the hydrostatic pressure
ECD equals static mud weight plus the additional pressure due to annular friction losses from fluid circulation, expressed as an equivalent density.
Question 6: What is the purpose of 'reaming' during drilling operations?
- To increase the mud weight
- To enlarge or clean an undergauge section of the wellbore (Correct answer)
- To set casing in the wellbore
- To measure formation resistivity
Correct answer: To enlarge or clean an undergauge section of the wellbore
Reaming involves rotating and circulating while moving the drill string up and down to enlarge tight spots or clean sections of the wellbore that have collapsed or swelled.
Question 7: In well control, what is a 'hard shut-in' procedure?
- Closing the annular preventer slowly while maintaining pump pressure
- Immediately closing the BOP with the choke closed after detecting a kick (Correct answer)
- Pumping heavy mud before closing the BOP
- Allowing the well to flow until pressure equalizes
Correct answer: Immediately closing the BOP with the choke closed after detecting a kick
Hard shut-in involves immediately shutting the well in by closing the BOP with the choke line closed upon detecting a kick, allowing accurate SIDPP and SICP readings.
SPE Drilling Engineering Principles 2
What is the primary purpose of a drill stem test (DST) in petroleum engineering?