CPG Quality Control & Process Improvement 3 — Questions and Answers
Question 1: Which Lean manufacturing concept focuses on eliminating waiting time between process steps in a petroleum laboratory workflow?
- Kaizen
- Flow (Correct answer)
- Pull system
- 5S
Correct answer: Flow
Flow, a core Lean principle, aims to make work move smoothly through each step without queuing or delay between process stages.
Question 2: During well log quality control, a geologist notices a caliper log shows enlarged borehole sections. What is the primary QC concern for other logs in those intervals?
- Elevated gamma ray readings due to tool compression
- Degraded resistivity and density log accuracy caused by poor pad contact or invasion (Correct answer)
- Overestimated sonic travel time due to cycle skipping in competent rock
- Incorrect depth correlation from the cable stretch
Correct answer: Degraded resistivity and density log accuracy caused by poor pad contact or invasion
In washed-out borehole sections, contact-dependent tools like density and microresistivity lose pad contact, producing unreliable measurements.
Question 3: What is the key distinction between precision and accuracy in analytical quality control?
- Precision measures closeness to the true value; accuracy measures repeatability
- Accuracy measures closeness to the true value; precision measures repeatability of results (Correct answer)
- Both terms are interchangeable in modern QC standards
- Precision applies to chemical analysis; accuracy applies to physical measurements only
Correct answer: Accuracy measures closeness to the true value; precision measures repeatability of results
Accuracy describes how close a measurement is to the true value, while precision describes how reproducible repeated measurements are.
Question 4: In a mud logging QC program, which parameter most directly confirms that lag depth corrections are applied correctly?
- Pit volume totalizer readings
- Correlation of gas peaks with formation tops from offset wells (Correct answer)
- Mud weight in vs. mud weight out difference
- Standpipe pressure trend
Correct answer: Correlation of gas peaks with formation tops from offset wells
Gas peaks that align with known formation tops from offset wells confirm that lag time and lag depth corrections are being applied accurately.
Question 5: A value stream map in petroleum project management is primarily used to:
- Calculate net present value of reserves
- Identify waste and non-value-adding steps across an entire workflow (Correct answer)
- Plot production decline curves
- Schedule rig operations using critical path method
Correct answer: Identify waste and non-value-adding steps across an entire workflow
Value stream mapping visualizes every step in a process to distinguish value-adding activities from waste such as waiting, rework, and overproduction.
Question 6: Which type of control chart is most appropriate for monitoring the proportion of defective items when sample sizes vary?
- X-bar and R chart
- p-chart (Correct answer)
- c-chart
- CUSUM chart
Correct answer: p-chart
The p-chart tracks the proportion (fraction) of defective units per sample and accommodates variable sample sizes.
Question 7: A formation evaluation QC checklist flags a zone where the neutron-density crossplot shows gas effect, but the resistivity log shows low values. What is the most likely QC issue?
- The gas effect is real and the zone is a dry gas reservoir
- Tool malfunction or borehole environmental effects are distorting one or more logs (Correct answer)
- The formation is an unconventional shale play
- The density log depth shift requires correction
Correct answer: Tool malfunction or borehole environmental effects are distorting one or more logs
Discordant log responses that physically contradict each other often signal tool malfunction, borehole washout, or environmental corrections not applied.
CPG Quality Control & Process Improvement 3
Which Lean manufacturing concept focuses on eliminating waiting time between process steps in a petroleum laboratory workflow?