Patent Application
20150260000
The field of the invention is fill up and circulating tools for running casing and more particularly a metal seal feature on the tools allowing for rapid deployment against the casing in the event of a well kick.
Casing fill and circulation tools are used to fill the casing as it is being built to run in the hole and then to circulate the string as it is lowered into the borehole. Circulation is typically carried out by having a self-actuating seal or an activated seal of a resilient material such as rubber contact the inner wall of the casing. Typically the seal of the fill up tool is kept outside the casing until there is a need to circulate and when that need arises the tool is lowered to get the seal inside the casing and against the casing inner wall. Various types of rubber seals have been used such as cup seals, inflatables or other constructions that are mechanically urged into contact with the inner casing wall. These designs serve well for holding back the pressures developed during circulation which are a function of the flow rate and the annulus size outside the casing as it is run into the hole. However, there is a possibility that the well may kick or blow out when casing is being run in. This kind of situation frequently requires a rapid response and the capacity to seal the inside of the casing against very high pressures. The resilient rubber seals of the past designs are not capable of holding such pressures. As a result what has been done in the past is that the fill up and circulating tool had to be pulled out of the casing after pumping heavy fluid through it to try to stabilize the well. However, in the interim period of pulling out the fill tool from the casing and threading on a valve, the well could actually blow again despite the pumping of heavy fluid. The present invention addresses this issue by allowing rapid deployment of a metal to metal seal without a need to pull out and lay down the fill up tool.
The following references represent the state of the art for fill up and circulating tool exterior seal arrangement designed to allow circulation as the casing is being run into the well: U.S. Pat. No. 5,584,343; EP0709543 A2; US 2013/0220610; WO 2012/021555 and U.S. Pat. No. 6,173,777. U.S. Pat. No. 5,439,061 is a casing hanger for a wellhead for placement between casing strings.
Those skilled in the art will better understand further aspects of the invention from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be found in the appended claims.
A fill up and circulating tool has a threaded hub covered by a rapidly removable cover. The cover protects the threads from damage until a well kick occurs. When the well kicks the cover is rapidly removed and the fill up tool is brought down with the top drive to which it is connected. The top drive rotates the mandrel of the tool to make the threads up to a coupling on the uppermost stand of casing to provide a metal to metal seal that can resist a well kick coming up through the casing and around the outside of the fill up tool. The top drive system has a surface valve that can be closed quickly to contain the kick through the fill up tool.
Referring to
In the event of a well kick with a pressure surge coming up the interior of the casing 3 the first response is to pump heavy fluid into the well to bring it toward stability and to buy time to lower the tool 1 to engage threads 6 with threads 5 to close off the casing 3 with a metal to metal seal in the form of an engaged thread. Note the positions of the bushing and coupling can be reversed but it is preferable to have the coupling on the top of the tubular string to protect its threads that are inside. The threading takes place with the assistance of the top drive that is schematically illustrated as 2. The exterior of the casing 3 can be sealed with blowout preventers that are not shown. IN a very short time without any need to remove the tool 1, the casing can be secured from a well kick with a metal to metal connection that can withstand the anticipated pressures from the kick.
Those skilled in the art will appreciate that one advantage of the present invention is that it is mounted to the tool 1 when used in normal operation of running and circulating a casing string into a desired subterranean location. The ability to actuate a metal to metal seal in short order allows a response to occur in a very short time to a well kick which can reduce risk of injury to personnel as well as damage to rig equipment. No longer does the tool need to be disconnected and set down on a rig floor in the face of an emergency situation of a well kick or imminent blowout. The safety risks of handling the tool and needing to place it on a crowded rig floor under emergency conditions is also avoided, which again has the benefit of reducing personal injury or equipment damage. While the resilient seals in the past that were used to hold low pressures were somewhat of a barrier, in the case of blowout they lacked the pressure retaining capacity and operators were unwilling to depend on such seals for service beyond their intended purpose of holding back the pressure needed to overcome friction when circulating the casing string. While such resilient seals can still be employed as before for containing the pressure needed for circulation, the metal seal can be used in tandem to add new functionality in an emergency situation that has not been available before in a casing running situation.
The above description is illustrative of the preferred embodiment and many modifications may be made by those skilled in the art without departing from the invention whose scope is to be determined from the literal and equivalent scope of the claims below:
