| 摘要 |
A hydraulic control sub assembly is used for actuating hydraulically operated downhole remedial tools, such as section mills or underreamers. The control sub features a drop ball mechanism to terminate the flow of drilling fluid to the hydraulic tool, thereby inactivating the tool. The control sub also has a hydraulic rupture disc that permits drilling fluid circulation when tripping the drill pipe. The control sub further contains upwardly directed jet nozzles to enhance fluid flow in the well bore to help clear away debris. A float valve is also incorporated in the control sub to ensure there is no fluid under high pressure trapped in the hydraulic tool that may jam the tool.
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