钻环是一种夹持钻头的圆环，它能使钻头在径向上对某个轴承定位。
机械卡钻可能由井眼内的碎屑、井眼内几何形状异常、水泥、键槽或者岩屑在环空中的积聚等引起。
Mechanical sticking can be caused by junk in the hole, wellbore geometry anomalies, cement, keyseats or a buildup of cuttings in the annulus.
方法利用体外培养的单层近融合期人RPE细胞，采用棉签和角膜移植用环钻做圆形细胞刮伤区，建立体外RPE细胞损伤模型。
Methods Cultured monolayer-confluent human RPE cells were scraped with a trephine and a cotton stick, and set up the injured model of RPE cells with round scraped area.
举例分析在环空和钻柱内的稳定流动过程中，随井深增加，压力、含气率、多相流体密度等的变化规律；
The steady-state flows in drill pipe and in annulus are analyzed and the variations of pressure, gas void fraction, and multiphase-flow density along the well depth are simulated.
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