SPE Production and Operations 2 — Questions and Answers
Question 1: What is the primary purpose of a wellhead choke in oil and gas production?
- To inject chemicals into the wellbore
- To control flow rate and maintain backpressure on the reservoir (Correct answer)
- To separate gas from liquid at surface
- To measure cumulative oil production
Correct answer: To control flow rate and maintain backpressure on the reservoir
A wellhead choke restricts flow to control production rate and maintain appropriate backpressure, protecting surface equipment and reservoir management.
Question 2: In artificial lift operations, which method uses a downhole pump driven by a surface prime mover via a sucker rod string?
- Electric Submersible Pump (ESP)
- Gas lift
- Beam pump (rod pump) (Correct answer)
- Hydraulic jet pump
Correct answer: Beam pump (rod pump)
A beam pump (rod pump) transmits surface motor energy downhole through a sucker rod string to drive a downhole plunger pump.
Question 3: What does the term 'skin factor' represent in reservoir engineering?
- The outer boundary condition of a reservoir
- A dimensionless measure of near-wellbore damage or stimulation (Correct answer)
- The permeability of the pay zone
- The thickness of the productive interval
Correct answer: A dimensionless measure of near-wellbore damage or stimulation
Skin factor (S) quantifies near-wellbore pressure drop beyond Darcy flow; positive skin indicates damage, negative skin indicates stimulation.
Question 4: During a production test, a stabilized flow period is followed by a shut-in period. This sequence describes which well test type?
- Drill stem test (DST)
- Pressure buildup test (Correct answer)
- Interference test
- Step-rate test
Correct answer: Pressure buildup test
A pressure buildup test involves flowing the well to stabilization then shutting it in to record the pressure recovery curve for analysis.
Question 5: Which chemical treatment is typically used to prevent paraffin wax deposition in production tubing?
- Scale inhibitor
- Corrosion inhibitor
- Pour point depressant (Correct answer)
- H2S scavenger
Correct answer: Pour point depressant
Pour point depressants modify wax crystal structure to lower the temperature at which paraffin solidifies, preventing deposition in tubing.
Question 6: In a three-phase separator, what force is primarily responsible for separating water from oil?
- Centrifugal force
- Gravitational settling due to density difference (Correct answer)
- Coalescing membrane filtration
- Electrostatic attraction
Correct answer: Gravitational settling due to density difference
Water separates from oil in a three-phase separator mainly by gravity as the denser water phase settles to the bottom.
Question 7: What is the function of a gas lift mandrel installed in production tubing?
- To anchor the tubing to the casing
- To provide a ported housing for gas lift valves that inject lift gas into the tubing (Correct answer)
- To act as a safety valve in case of surface blowout
- To measure downhole pressure and temperature
Correct answer: To provide a ported housing for gas lift valves that inject lift gas into the tubing
A gas lift mandrel is a special tubing joint that houses a gas lift valve, enabling injection of high-pressure gas from the annulus into the tubing to reduce fluid density.
SPE Production and Operations 2
What is the primary purpose of a wellhead choke in oil and gas production?