农历和阴历一样吗>什么是区域活动
专利名称：Downhole safety valve
发明人：WILHELMUS HUBERTUS PAULUS MARIA HEIJNEN
申请号：AU1019401
申请日：20000921
公开号：AU761584B2
公开日：
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摘要：A safety valve for u in a wellbore formed in an earth formation, comprising a valve body having a fluid passage for passage of a stream of hydrocarbon fluid flowing from the earth formation via the wellbore to the earth surface, a closure member movable relative to the valve body between an open position in which the fluid passage is open and a clod position in which the closure member clos the fluid passage, and an activating device for lectively subjecting the closure member to a drag force of lected magnitude, the drag force being exerted by the stream of fluid and inducing the closure member to move from the open position to the clod position thereof.The safety valve further compris control means for controlling the activating device to subject the closure member to said drag force.
媒介融合申请人：SHELL INTERNATIONALE RESEARCH MAATSCHAPPIJ B.V.剑开头的成语>森林防火小常识
昼之王夜之枭
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