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Reservoir case studies |
1 Baker Atlas Geoscience, PO Box 18665, Manama, Bahrain (e-mail: ismail.ozkaya{at}bakerhughes.com)
2 Petroleum Development Oman, PO Box 81, Muscat, Sultanate of Oman
Borehole image logs, without accompanying flowmeter logs, are found to be of little use in identifying fluid conductive faults and fractures in a clastic reservoir in Oman. Both high permeability opening mode fluid conductive fractures and low-permeability deformation bands filled with sand and clay gouge appear conductive on image logs. Regional tectonic evolution and the nature of structural elements do not provide sufficient information to differentiate fluid conductive seismic faults or fault segments. Rapid water breakthrough may be indicative of fluid conductive faults and large fractures, but water cut rise is complex. The effect of faults and fractures may be masked by spud date, and water fingering through highly permeable layers, especially when the percentage of fluid conductive fault segments and fractures is low. Faults, deformation bands and large conductive fractures are found to cause openhole log spikes in this field. Since openhole logs are available from a large number of horizontal wells, it becomes feasible to prepare risk maps from map distribution of openhole log spikes even though it is not possible to pinpoint the exact location of fluid conductive faults and large fractures.
