Sometimes in development wells, open hole logs are not available due to hole problems or high inclination. Under such conditions it becomes difficult to locate the oil-water (0/W) contact and select the layer to perforate for production. The cement bond log (CBL) and variable density log (VDL), which are recorded to assess the quality of cementation, are useful to identify the O/W contact. This is possible because it is observed that the compressional wave has different travel times for oil bearing layers than for water bearing layers in the same lithology. This seems to be a valid method in some cases where open hole logs are not available for determining the oil-water contact. Agreement is quite good with open hole log analysis and with the general O/W contact of the field.

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