Title : Quad Neutron Measurement - Seligi Experience
Behind casing OWC determination using conventional Pulse Neutron Logging Tool (Sigma & C/O) is very challenging in Seligi Field due to:
I. Low contrast in Sigma response between oil and water zones due to low salinity (11-30K) formation water environment.
II. Shallow depth of logging tool investigation, maximum 9 inches. Poor borehole quality (damaged casing, borehole enlargement – as a result of sand production)
and borehole fluid invasion masked the actual formation response lead to wrong interpretation.
Quad Neutron Logging tool was selected as a potential monitoring tool for the field as the vendor claimed that it has it has deeper depth of investigation, between 2 -3 ft, compared to other conventional
pulsed neutron tools (maximum depth of investigation 9 inches), thus able to read beyond tubing and casing without requiring pulling out completion string. This is important criteria for fluid contact monitoring
in brown fields where borehole fluid invasion from high water cut wells masked the actual formation response thus lead to wrong understanding about the reservoir performance.
Quad Neutron validation process is ongoing by comparing the interpreted logs results with production test data to establish suitable operating range for the tool. Integration with all the available information is
important in interpreting cased hole logs to avoid inconclusive or wrong interpretation.
Wan Abdul Manan graduated with a BSc(Chem.Eng) from University of Salford and an MSc (Chem Eng) from Imperial College. Joined Sarawak Shell Malaysia
upon graduation in 1990 and worked as a Well Site Petroleum Engineer for 1.5 years before joining Petrophysical Engineering Department.
He has also worked for Carigali Triton, Qatar Petroleum, Murphy Oil and Enquest. Currently he is a Lead Petrophysicist for Enquest, responsible for
both Studies and Operation Petrophysics.
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