If pipelines are not flown as many of the majors are regularly flown over for monitoring, it can be difficult to discover relatively small leaks before they become big leaks.
Fly-over is for more than looking for oil on the ground. They will notice and investigate a dead/dying vegetation along the right-of-way that could indicate a below grade seeping into the soil.
Also the make notice of construction equipment that had not previously notified the pipeline company as required if digging in the area. Those will have someone quickly driving out.
But measurement in and out of pipeline are not perfectly accurate. It can be difficult to see the difference quickly until a trend line develops.
Typically, the best prevention is proper maintenance. The pipelines have corrosion prevention system like impressed current rectifiers, sacrificial anodes, etc. Inspection and noticing changes of those along with smart-pigging for internal measurement can prevent many problems before they spill.
My experience over the last 20 years with how humans react
when pipeline and/or storage tank inventory numbers don’t match up:
- first they suspect the meter:
“that can’t be right”,
“check the math in the spreadsheet”,
“the meter must need to be calibrated”.
- second they suspect other people:
“somebody is not reading the meter correctly,
“somebody must not be reporting all of their usages”,
“somebody must be stealing product”.
- finally after at least a few weeks and perhaps a few months,
they have to face the fact that there is a leak somewhere,
and then they have to go and find it.
It brings back memories when you talk about flying the lines.
As kids, we got parachute drops of candy from “The Flying Santa Clause”.
-
The Tuscaloosa News - Dec 15, 1957
http://news.google.com/newspapers?nid=1817&dat=19571215&id=hGUeAAAAIBAJ&sjid=5JkEAAAAIBAJ&pg=6083,2406849
-