Answer: Water saturation of shale layer cannot be determined in the log because shale is a very fine-grained sedimentary rock that contains a significant amount of clay minerals. These clay minerals are highly absorbent and can hold a large amount of water, which makes it difficult to accurately determine the amount of water saturation in the rock using logs. Additionally, the high clay content of shale can also interfere with the measurements taken by the log, making it difficult to obtain accurate readings.
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