关键词: 采油四通, 钻进四通, 换装, 井控, 可回收

Abstract: In the process of well testing and oil production, drilling spools need to be replaced with production spools as per technical requirements. In the operations, the wellhead is out of control for a period of time, so that there is a great potential safety hazard for well control. The conventional method to handle the problem is to temporarily seal off the wellhead with a bridge plug or to replace the spool with a multi-function testing tubing string. The measure can ensure the essential safety of operations, but the multifunctional tubing string has some disadvantages, such as complicated structure, longer operation period, casing damage caused by drilling and milling the bridge plug, troubles of retrievable bridge-plug tools which are difficult to deal with and so on. All of these problems are unfavorable to oil and gas well safe and efficient development. To eliminate the above problems, engineering technical personnel of Tarim Oilfield developed retrievable casing plugging valves used to plug casing when replacing spool in well testing and workover operations. With an operational pressure of 52MPa, the tool is mainly composed of a sealing unit, a setting and releasing unit, anchoring unit and running and retrieving unit, etc. The pressure test can be conducted before the tools being retrieved, and established a passage for well killing. A good result has been obtained on field application, such as the time for replacing the spools was decreased from 176h to 11h, and the one-time success rate reached 100%, which improved the wellbore integrity and reduced the operation costs.