循环接头是下套管中途或下完套管时循环钻井液用的专用接头，分为套管螺纹循环接头和由壬螺纹循环接头。
循环接头技术参数如下
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钻杆母螺纹
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套管螺纹
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水眼mm
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长度mm
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NC38
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5″偏梯扣BTC
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57
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400
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5″长圆扣LTC
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5″短圆扣STC
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NC38
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5″偏梯扣BTC
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57
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400
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5-1/2″长圆扣LTC
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5-1/2″短圆扣STC
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NC50
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7″偏梯扣BTC
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71
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460
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7″长圆扣LTC
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7″短圆扣STC
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NC50
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9-5/8″偏梯扣BTC
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71
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460
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9-5/8″长圆扣LTC
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9-5/8″短圆扣STC
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NC50
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10-3/4″偏梯扣BTC
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71
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480
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10-3/4″长圆扣LTC
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10-3/4″短圆扣STC
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NC50
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13-3/8″偏梯扣BTC
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71
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480
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13-3/8″长圆扣LTC
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13-3/8″短圆扣STC
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