Statistical Observation-Acoustic Example

Sturgeon Lake Acoustic Example


This example shows how statistically consistent acoustic data can be created for wells that don’t have acoustic data.  This application is important because it helps integrate well log data to acoustic/seismic modeling of reservoirs. 


There are a lot of wells that do not have acoustic data.  The ability to generate statistically consistent acoustic data from wells without acoustic can greatly assisted the seismic modeling process.


The data is from the Leduc Formation in the Sturgeon Lake Pool region of Alberta.  Most of the wells in this pool have older electrical logs and older neutron-gamma ray logs.  There are a few modern well logs available.


To generate acoustic data for the wells with older neutron data, the older neutron data was converted from counts per second to porosity and then with the gamma ray normalized to be consistent with the available modern well data.


A composite contour cross plot of the modern neutron vs. gamma ray was generated and overlaid with a grid as shown below.

neutron-gamma grid cross plot

The modern well data set was then scanned to develop an observed acoustic spectrum for each of the cells in the overlay.

acoustic hists on neutron vs. gamma

Based on these observed statistics, a pseudo-acoustic was derived as shown.  For a given depth in a given well, a neutron-gamma data pair was observed.  This data pair was crossplotted on the modern data crossplot to find the appropriate grid cell.  Based on the observed acoustic spectrum of this grid cell, a pseudo acoustic was derived for the minimum observed acoustic, the most likely acoustic as well as the maximum acoustic based on the observed spectral data.

acoustic prediction

The following graphic shows the pseudo-acoustic for wells with modern acoustic data for comparison and for one well that had older neutron data.  As can be observed, the pseudo-acoustic data replicated the actual modern acoustic data quite well.  Based on this observation, the pseudo-acoustic derived for the well with the older neutron data can be used with confidence.

acoustic prediction multi-well

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