Data Quality Control
One of the jobs of the wireline witness or log witness is to ensure the data gathered during the logging job, especially when several suites of tool are run, is properly managed and presented.
Typically the wireline witness is at the wellsite during wireline logging and is close to the action. As data is acquired, this data usually needs to be processed by the logging engineer before being transmitted to the client. In this process, several data sets are created which are either not yet depth-corrected or without correct wellsite header information.
A Wireline Log
The client does not want to be bombarded with all the data that was generated during this process but only the corrected and QC'ed log data which he can put into his software for detailed log analysis and interpretation.
Therefore it is the job of the wireline witness or log witness to act as a filter between the logging engineer and the client, effectively to capture all mistakes and/or errors and correct them before the data gets to the client. This is normally the job that the service company field manager would do at the office after the job. However since the client needs the data immediately they are acquired at the wellsite, the wireline witness does this job.