Blueback Investigator Quick Guide

Examples

Porosity depth trend ID and detrending

Well logs

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Option for introduction slide.

Porosity depth trend ID and detrending

Depth trends are often observed in porosity data. For various modeling operations it is often required to cancel out the depth trend

Build a porosity vs depth investigation and plot depth vs porosity. Add a discrete zone log, if you see different trends in different zones.

Display depth vs porosity in a 2D cross-plot

Porosity depth trend ID and detrending

Run a linear regression using “x=my+c” Filter on the zone property if applicable

Read off datum depth on the depth axis, example below: datum= -2170 meters, gradient from regression=0.000088

Calculate detrended porosity: detrendedPOR = originalPOR + (datumdepth – depth) * gradient

In the Petrel log calculator, it looks like this:  PHI_detrend= Porosity+(-2170-Z)*0.000088

Porosity depth trend ID and detrending

Add the detrended porosity well logs as a new data set to the investigation and plot against original porosity for QC

Original porosity in blue, detrended porosity in orange

Porosity depth trend ID and detrending

Plot detrended vs original porosity logs in WSW

Original porosity in green, detrended porosity in black