Uninstalling Petroleum Office

Petroleum Office is a normal Windows application, so it uninstalls the normal way.

Removing the Add-in

  1. Close Excel
  2. Open Settings → Apps → Installed apps in Windows (or Programs and Features on older versions)
  3. Find Petroleum Office and choose Uninstall
  4. Follow the prompts

Closing Excel first matters. The add-in loads into every running Excel process, and an uninstall while Excel is open can leave files behind that need a second attempt after a restart.

When it finishes you may land on a short confirmation page on this website. That page is only a receipt — nothing further is required.

What Happens to Your Workbooks

Workbooks are not modified by uninstalling, but what they show changes depending on what they used.

  • Add-in functions — any formula calling a PO. function returns #NAME?, because the function no longer exists on that machine. The formula text is intact, so reinstalling restores the results.
  • Lambdas — these live in the workbook as defined names, but each one calls a Petroleum Office function underneath, so they return #NAME? too. See Using Lambdas.
  • Blueprints — a blueprint is ordinary cells and formulas once inserted. Labels, inputs and layout survive; any cell calling a PO. function shows #NAME?.
  • Imported data — sheets produced by LAS Import, Eclipse Import or Case Generation are plain values and stay exactly as they are.

If you need results preserved for someone without the add-in, convert the formulas to values before uninstalling: select the range, copy, then Paste Special → Values.

Reinstalling or Moving Machines

Reinstalling restores everything: the same installer from the download page, then sign in again. Your licence follows your account rather than the machine, so there is nothing to release or transfer first — see Licensing and Your Account.

Workbooks that showed #NAME? recalculate normally once the add-in is back and you reopen them.

If the Tab Is Still There After Uninstalling

A leftover Petroleum Office tab, or #NAME? alongside a tab that still appears, usually means Excel was running during the uninstall. Restart Excel first. If the tab persists, see the add-in registration steps in Troubleshooting Common Errors — the same Excel Add-ins list that enables the add-in also shows an entry left behind by an incomplete removal.

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