Patent Application
20050115720
The field of the invention is high expansion bridge plugs and more particularly those that are run through tubing on coiled tubing and set below the tubing in much larger casing.
Many times during the life of a well certain perforations need to be closed off for a variety of reasons, one of which is that the formation begins to produce water or other contaminants in large quantities. A convenient way to do this is to use a bridge plug. Bridge plugs that are small enough to run through existing tubing and then get set in casing below the tubing can be used to avoid the time and expense of removal of the production tubing from the wellbore. There are several ways to get the bridge plug to the desired position. The faster ways include coiled tubing and electric line. Additionally, rigid tubing stands can be threaded together to deliver the bridge plug. Rigid tubing is a slower process, normally requires the well to be killed and therefore is less economical.
Electric line used in combination with a locally set explosive charge can provide the needed force on a small piston area that is necessitated by a through tubing application to get the required amount of setting force to set the bridge plug and release from the setting tool. Such electric line set setting tools can also achieve the very long stroke required to effectively set a through tubing bridge plug in far larger casing. These stroke requirements can reach as long as about 2 meters. However, depending on well depth and trajectory, it may not be possible to advance the bridge plug through the tubing with electric line. In such situations, the coiled tubing alternative is the alternative with the shortest run in time.
Another issue with electric line run through tubing bridge plugs is that frequently after the bridge plug is run through tubing and set in casing, cement is delivered on top of the set bridge plug to aid in sealing off the perforations in question. The normal way this cement is delivered is using multiple trips with a slender carrier that is run down to the set bridge plug, where the cement is released. Sometimes 6 or 7 round trips may be required to deliver the requisite volume of cement on top of the bridge plug. This process not only takes time but also introduces other pitfalls in getting the proper cement placement.
Coiled tubing also has limitations in an application of a through tubing bridge plug. The pressure that needs to be developed in the coiled tubing at the surface to get the required force to set the packer and release from it could be in the order of 11-15,000 pounds per square inch (PSI). Ordinary coiled tubing is generally limited to about 5,000 PSI maximum working pressure. Special order coiled tubing to take higher pressure can be located in some markets, but its availability is so limited and its cost so prohibitively high so as to make running the bridge plug through tubing not economically worth while. In deviated wellbores, coiled tubing can be effective at delivery of a through tubing bridge plug to the desired location, where an electric line is not workable. The problem is how to get the required setting force with the pressure limitations on generally available types of coiled tubing.
The present invention seeks to overcome these shortcomings of coiled tubing for delivery and set of through tubing bridge plugs and other downhole tools that require high forces to set. One solution offered by the present invention is to place a pressure amplifier adjacent the through tubing bridge plug so that lower pressures at the surface can set the tool downhole. While this solution has possibilities, it also brings about additional issues of having to configure amplifiers for particular applications and, as a result, requires technicians with greater skills than may be available at a well site when the bridge plug is run. Additionally, incorporating a pressure booster also ads cost in a situation where the additional cost may make running the through tubing bridge plug not economically feasible. Accordingly, in a preferred embodiment of the present invention a multi-step setting process is envisioned. It begins with hydraulic pressure applied through the tubing to initiate the set and is followed by a pulling force to continue the process. Where pulling alone will not result in a sufficient setting force, tools such as jars or impact hammers can be tripped with the pulling force applied to the coiled tubing to enhance the setting force. Those skilled in the art will more readily appreciate these and other aspects of the present invention by a review of the description of the preferred embodiment, the drawings and the claims, which appear below.
A through tubing downhole tool, such as a bridge plug is delivered on coiled tubing. The setting process entails an initial pressurization to anchor the tool and compress its sealing element. The remainder of the needed force for setting the tool can come from an upward pull on the coiled tubing. Should more force than can be delivered from a pull on the coiled tubing be required to finish the setting and releasing process from the downhole tool, a jar or impact tool can be incorporated to boost the applied uphole force that is delivered from the pull on the coiled tubing at the surface. Alternatively, a pressure amplifier can be fitted to the coiled tubing so that a smaller pressure applied to the coiled tubing at the surface can deliver the required force to set and release from the downhole tool.
Referring to
In some applications the combination of pressure, in the order of about 500-1000 PSI, combined with pulling of the coiled tubing will not be enough force to set the bridge plug 10 and break the link 26. In that case, as shown in
An alternative way to set the bridge plug 10 is to insert a pressure amplifier in the location where the tool 28 is shown in
Those skilled in the art will appreciate that a variety of downhole tools, apart from bridge plugs, can be set using the techniques described above. In situations where well conditions do not permit electric line delivery and where through tubing is the preferred technique, the methods of the present invention allow for delivery of required setting and release forces applied to a running tool while making use of the tensile capabilities of the coiled tubing. The incorporation of force enhancing devices to the coiled tubing further broadens the spectrum of applications where a greater setting force could be required. Alternatively, pressure amplifiers can be used with coiled tubing to deliver a setting pressure at the running tool that is well in excess of the capabilities of the surface equipment and the coiled tubing itself. While rigid tubing can be used, coiled tubing is preferred because it is much more economical to run in a through tubing application. The present invention is not limited to through tubing applications, but the greatest economies can be achieved by using the methods of the present invention in such applications.
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:
This application claims the benefit of U.S. Provisional Application No. 60/526,214 filed Dec. 2, 2003.
| Number | Date | Country | |
|---|---|---|---|
| 60526214 | Dec 2003 | US |
