Gudao oilfield has so loose a lithology that the distribution of oil and water can't be identified by means of the conventionalcoring method.
孤岛油田岩性极为疏松，用常规钻井取心的办法不能较好地分析和认识油层的油水分布规律。
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The basic difference of outside-vent coring tool from conventional one is that it has a special outside-vent joint installed between safety joint and swivel assembly.
The wire-line coring tool of HSQ serial has kept up the technical features of conventional placer drills and derived the advanced structure from steel cable fishing tool for inner barrel.