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A comparison of logging while drilling (LWD) and wireline acoustic measurements

Comparison of LWD and wireline acoustic measurements
Authors: Briggs, Victoria Alice, 1974-;

A comparison of logging while drilling (LWD) and wireline acoustic measurements

Abstract

The instruments used to measure borehole acoustic data can be classified as either wireline or logging while drilling (LWD). The wireline tool measures formation speeds after the borehole is drilled, and the LWD tool measures formation speeds while the borehole is drilled. This thesis focuses on comparing the data collected by these tools and how formation properties affect their measurements. LWD and wireline measurements taken from the same borehole are compared. Discrepancies in estimated shear and compressional velocities, as calculated by time semblance methods, were found between the two data sets. We modeled radially layered formations with increasing or decreasing radial velocity profile to estimate the acoustic measurement penetration for each tool. We reprocessed sections of the data using frequency semblance methods and compared with layered model results. We found that a frequency-domain analysis is feasible and reduces the overall difference between the LWD and wireline shear and compressional velocity estimates. The remaining discrepancy can be explained by the different radial depths of penetration of these two tools, which naturally leads to a difference in the velocity estimates when there is a radial gradient in the velocity profile.

Country
United States
Related Organizations
Keywords

and Planetary Sciences, Earth, Atmospheric, and Planetary Sciences., Earth, Atmospheric

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selected citations
These citations are derived from selected sources.
This is an alternative to the "Influence" indicator, which also reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Citations provided by BIP!
popularity
This indicator reflects the "current" impact/attention (the "hype") of an article in the research community at large, based on the underlying citation network.
BIP!Popularity provided by BIP!
influence
This indicator reflects the overall/total impact of an article in the research community at large, based on the underlying citation network (diachronically).
BIP!Influence provided by BIP!
impulse
This indicator reflects the initial momentum of an article directly after its publication, based on the underlying citation network.
BIP!Impulse provided by BIP!
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Average
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