CPG Quality Control & Process Improvement 2 — Questions and Answers
Question 1: Which statistical tool is used to identify the most significant causes of defects by ranking them in descending order of frequency?
- Control chart
- Pareto chart (Correct answer)
- Scatter diagram
- Histogram
Correct answer: Pareto chart
A Pareto chart ranks defect causes by frequency so teams can focus on the vital few issues that cause most problems.
Question 2: In petroleum seismic data processing, what QC step helps detect systematic errors introduced by a faulty geophone group?
- Spectral whitening
- Shot gather QC (Correct answer)
- Deconvolution
- Migration velocity analysis
Correct answer: Shot gather QC
Shot gather QC allows identification of dead, noisy, or consistently anomalous traces linked to malfunctioning receiver groups.
Question 3: What is the purpose of a repeatability test in a quality control program for geochemical sampling?
- To compare results from two different laboratories on the same samples
- To verify that duplicate samples collected at the same location give consistent results (Correct answer)
- To assess inter-analyst variability within one lab
- To calibrate the analytical instrument to known standards
Correct answer: To verify that duplicate samples collected at the same location give consistent results
Repeatability tests check that field duplicates from the same location produce consistent analytical results, confirming sampling precision.
Question 4: Six Sigma process improvement defines a defect opportunity as:
- Any step in a process where human error is possible
- Any measurable characteristic of a product that can fail to meet customer specifications (Correct answer)
- Any rework step identified in a value stream map
- Any process step that exceeds its cycle time
Correct answer: Any measurable characteristic of a product that can fail to meet customer specifications
A defect opportunity is any measurable characteristic that could fail to meet the defined specification or customer requirement.
Question 5: A drilling team notices ROP dropping progressively over multiple bit runs at the same depth interval. Which QC/process improvement step best addresses this trend?
- Replace the derrick immediately
- Conduct root cause analysis on bit selection and drilling parameters (Correct answer)
- Increase mud weight significantly
- Switch from rotary to sliding drilling exclusively
Correct answer: Conduct root cause analysis on bit selection and drilling parameters
Root cause analysis examines bit selection, WOB, RPM, and formation hardness to identify and eliminate the underlying cause of ROP decline.
Question 6: What does a process capability index (Cp) value less than 1.0 indicate?
- The process is centered within specification limits
- The process spread exceeds the specification width and will produce defects (Correct answer)
- The process is operating in statistical control
- The sample size is insufficient for analysis
Correct answer: The process spread exceeds the specification width and will produce defects
A Cp < 1.0 means the natural process variation (6 sigma spread) exceeds the specification tolerance, guaranteeing out-of-specification output.
Question 7: In core analysis QC, what is the role of a 'check sample' or 'blind duplicate'?
- A sample intentionally contaminated to test detection limits
- A previously analyzed sample re-submitted without the lab's knowledge to assess reproducibility (Correct answer)
- A standard reference material with certified values
- A sample collected from a different well for cross-well comparison
Correct answer: A previously analyzed sample re-submitted without the lab's knowledge to assess reproducibility
Blind duplicates are resubmitted under a different ID so the lab cannot distinguish them, giving an unbiased measure of analytical reproducibility.
CPG Quality Control & Process Improvement 2
Which statistical tool is used to identify the most significant causes of defects by ranking them in descending order of frequency?