There are two common tests for quality and completeness. These are :

The following data attributes from the Axxses catalogue will be compared to Chevron's own data for :

Quality

• Wellname
• Curve Mnemonic
• Tool Mnemonic
• Top Logged Interval
• Bottom Logged Interval
• Minimum and maximum amplitude values (if available from Axxses).

Completeness

All data sent to CDA will be checked for completeness - i.e. that all curves provided are present in the Axxses catalogue. The quality check will concentrate principally on those curves that appear on the final set of edit paper prints.

New Wells

Final edit tapes from the logging contractor will be quality controlled by the Operations Group in Aberdeen. This quality control will ensure that the wireline and LWD data from the well is the most complete and accurate representation of the data acquired at the wellsite. Once the Operations Group has verified the data it will be sent to CDA.

On receipt of confirmation from CDA that the data has been successfully loaded to LogDB, the Operations Group will test for quality and completeness.

Furthermore for new wells, all the curves that appear on the final set of edit paper prints will be played back from tape and verified internally by Chevron before the final edit tape is sent to CDA.

Historic Wells

Wells that Chevron has operated before the first Alba well will be quality controlled by the Exploration Log Analyst according to the following procedures:

Where data has been loaded on Chevron's behalf by another operator the following procedure will be followed:

• The final well report will be retrieved from well records to identify which logs should be available for the well including which logging tools were used over what interval, and what data types were recorded by those tools.
• The data available from the Axxses catalogue will then be checked for quality and completeness.

Where data has not been loaded on Chevron's behalf by another operator the following procedure will be followed,-

• The final well report will be retrieved from well records to identify which logs should be available for the well including which logging tools were used over what interval, and what data types were recorded by those tools.
• The relevant wireline tapes that contain this data will then be retrieved from storage and loaded to Mincom's Geolog to ensure that all data identified in the final well report is present. This will ensure data completeness. The well history file for the well will their be checked to ensure data quality.
• These tapes will then be sent to CDA for loading to LogDB.
• On receipt of confirmation from CDA that the data has been successfully loaded to LogDB, the exploration Log Analyst will then test for quality and completeness.

If the data provided by another operator is of insufficient quality or completeness according to the above procedures, Chevron will request CDA to delete all data for the well and will follow the procedure for wells that do not have any data provided by another operator as detailed above.