| 摘要 |
<p>Dual safety valve apparatus is utilized to automatically shut in one or a pair of producing well zones upon a reduction in control fluid pressure. A tubing hanger is run into the well on a setting tool and supports a dual tubing string when the hanger is set in the well casing. The setting tool is removed and a dual, full opening shutoff valve assembly is run into the well and seats in the tubing hanger. Control fluid pressure supplied from the top of the well holds the shutoff valves open. Each shutoff valve has a full bore opening therethrough in the open position. A shifting tool is operable by fluid pressure to mechanically open the shutoff valves and when mechanically opened by the shifting tool, the valves can receive a secondary wireline retrievable shutoff valve operable by control fluid pressure. The dual shutoff valve is retrievable, and the tubing hanger is then retrievable by a retrieving tool.</p> |
