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Joined: Wed Feb 06, 2013 12:06 pm
Posts: 2
Hello there,

I need some advice in petrophysic here.

So, I currently working some petrophysic jobs now, there are 39 wells to be analyzed.
Im a bit confused between between PEF and SNPE, are they same type of logs or not?

The wells that have PEF type log shows a constant PEF value for Shale, it is about 3 - 4.
But, the well that have SNPE type logs shows vary value for Shale, its abput 4 - 8.

I made a SNPE vs Den and PEF vs Den crossplot, it describe what happen on my case.

So are they same logs or not? if they are different type of logs, can it be converted into conventional PEF logs?

Thank You

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Last edited by eppoch2 on Tue Mar 12, 2013 1:21 am, edited 1 time in total.

Sat Feb 23, 2013 7:53 am

Joined: Tue Apr 05, 2011 8:38 am
Posts: 80
PEF is Photoelectric Effect Factor log recorded by wireline conveyed logging tools.
SNPE is Smoothed Near Detector Photoelectric Effect Factor log, recorded using LWD (Logging While Drilling) tools. Most probably it is a log recorded by Halliburton Sperry Sun drilling services.
Theorectically, both PEF and SNPE should be giving you similar readings.
However, since SNPE being an LWD log as well as using the near detector only, it may have different readings when compared to wireline log PEF. Furthermore, the wireline log can be more affected by borehole conditions and mud cake.
Having said that, the PEF values of 3-4 for shales seem more reasonable than the SNPE values.
Maybe the SNPE log is affected by barite in the mud, making it read higher.
If the PEF or SNPE values are reasonable in the reservoir zones, it should be alright to use both these logs.
I don't think there is a way to convert SNPE into PEF log.
However, you may be able to normalize the SNPE log to a PEF log from a key well.

Sat Feb 23, 2013 2:33 pm
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