Comparison Errors

A comparison runs several rod pump designs side by side so you can see how a change (a different pumping unit, a heavier rod string, a higher stroke rate) moves loads and production. Something in that flow isn't working. Here's how to diagnose and fix it.

How Comparisons Work

You build a comparison by selecting two or more simulations on a well's RodSim tab and clicking Compare. The first simulation becomes the base simulation: your reference point. It always appears first and can't be deleted.

Each additional scenario starts as a duplicate of the base case, which you then edit. The important thing to understand: scenarios are independent copies. Once you edit a scenario, it diverges from the base and from the original simulation it came from. Changing a scenario does not change the base, and re-running the comparison does not touch your original single-run simulations.

Comparison Won't Create

The Compare button is grayed out, or clicking it does nothing.

No Simulations Selected

You need to select at least two simulations before you can compare them.

Fix:

1. Go to the well's RodSim tab
2. Check the boxes next to two or more simulations
3. Click Compare

Selected Simulations Were Never Run

A comparison compares results, so every simulation you select must have been run at least once.

Fix:

1. Open each simulation you want to include
2. Click Static (or Dynamic) and wait for it to complete
3. Return to the RodSim tab and select them again

If a simulation won't run, resolve that first. See Simulation Errors.

Simulations Are From Different Wells

A comparison lives on one well. You can't mix simulations from different wells into the same comparison, because they don't share geometry, survey, or fluid context.

Fix: Select simulations that all belong to the same well. To compare designs across wells, export each report separately and compare them by hand.

Comparison Won't Run

You clicked Run Comparison but it didn't finish cleanly.

One Scenario Is Stuck

Scenarios run one at a time. If progress stalls on a single scenario, that scenario most likely has invalid inputs the simulator can't get past.

Fix:

1. Expand that scenario's card on the Comparison Inputs page
2. Look for validation errors or red-highlighted fields
3. Correct the inputs and click Run Comparison again

All Scenarios Fail

When every scenario fails, the cause is usually something shared. Because each scenario starts as a copy of the base, a bad input on the base (for example an invalid directional survey, a missing PSN depth, or a broken rod string) propagates to every copy.

Fix:

1. Open the base simulation and confirm it still runs on its own
2. Check the directional survey and other well-level inputs
3. Fix the base, then rebuild or re-run the comparison

For the specific validation and runtime messages you may see, refer to Simulation Errors.

Some Succeed, Some Fail

Scenarios run independently, so if one fails the rest keep processing. A single failure almost always means that specific scenario has invalid inputs: a missing required field, an out-of-range value, or a rod string that no longer matches PSN depth after you edited it.

Fix:

1. Note which scenarios failed (they show an error message in results)
2. Expand each failed scenario and check its inputs
3. Correct them and re-run

Common per-scenario culprits are listed in Simulation Errors.

Results Look Wrong

The comparison ran, but the numbers don't make sense.

Numbers Are Identical Across Scenarios

If two scenarios show the same results, their inputs are probably still the same. A new scenario is created as an exact duplicate of the base, so until you actually change something, it produces identical output.

Fix:

1. Expand each scenario card
2. Confirm the inputs you meant to vary (pumping unit, rod string, tubing, stroke rate, production target) are actually different
3. Make your edits and re-run the comparison

Results Don't Match the Original Single Run

Comparison scenarios are copies. They diverge from the original simulation the moment you edit them, so the comparison reflects the scenario's inputs, not whatever the original simulation currently holds. If you changed the original after building the comparison, the two will not agree.

Fix: Treat the comparison as its own set of designs. If you want a scenario to match a specific single run, open both and reconcile the inputs field by field, then re-run.

Large Comparisons and Performance

Because scenarios run sequentially, total run time scales with the number of scenarios and how heavy each one is. A five-scenario comparison with complex rod strings and detailed surveys takes noticeably longer than a two-scenario one.

Comparison reports bundle every scenario into one PDF, so they are larger and slower to generate than a single-simulation report. If a comparison report times out or won't download, try exporting the scenarios individually and see PDF Export Fails.

When to Contact Support

Reach out to support@petrobench.com if:

• A comparison fails even though each simulation runs fine on its own
• Scenarios stay stuck with no error message
• Results look wrong despite inputs you've verified are correct
• The comparison report consistently fails to generate

Include:

• Well name and comparison name
• Which scenarios failed or looked wrong
• A screenshot of the error or results
• What you've already tried