| 摘要 |
A downhole safety valve for a central circulation completion system which comprises an inner tubular member that extends through an outer tubular member and a production bore which is defined between the inner and outer tubular members. The downhole safety valve comprises a generally cylindrical body which includes an outer surface and a through bore that extends generally axially through the body. The body is secured to the inner tubular member and is sealed to the outer tubular member to thereby form a pressure barrier between a first portion of the production bore located below the body and a second portion of the production bore located above the body. The downhole safety valve further comprises at least one flow passage which extends through the body and communicates between the first and second portions of the production bore, and at least one closure member which is disposed across the flow passage to control fluid flow between the first and second portions of the production bore.
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