Patent ID: 12228004

DETAILED DESCRIPTION

In the following description, numerous details are set forth to provide an understanding of the present disclosure. However, it will be understood by those skilled in the art that the embodiments described may be practiced without these particular details. Further, numerous variations or modifications may be employed which remain contemplated by the embodiments as specifically described.

Embodiments are described with reference to certain land-based oilfield operations. For example, operations in which an onshore well is being installed, completed and tested is illustrated. In the embodiment shown, the wellhead assembly for the well is manually accessible along with an exterior test port for testing of the wellhead seal which is a ring gasket at the interface of the wellhead and base. However, a variety of different well types may take advantage of an exterior test port in this manner. For example, even subsea wells may take advantage of such wellhead architecture. Indeed, so long as the wellhead assembly includes an exterior test port for testing of an internal primary seal in combination with a secondary seal to facilitate the testing, appreciable benefit may be realized.

Referring now toFIG.1, a side cross-sectional view of an embodiment of a wellhead assembly101is illustrated with an exterior test port100. The assembly101includes a wellhead130that is mounted to a base140which together define a wellbore180and provide a platform from which other well devices may be used to mange the wellbore180. The wellhead130and base140meet at an interface120which is sealed by a primary seal125to prevent leakage of wellbore fluids through the potential leak path of the interface120. In the embodiment shown, other coupling features such as a collar device190and guide pins175are provided to facilitate the mating of the wellhead130as described.

The noted exterior test port100is for the primary seal125at the interface120. More specifically, the test port100is fluidly coupled to the seal125at the interface120by way of an intentional leak path110. This allows for the introduction of pressure to the seal125to test and confirm functionality thereof. For example, as detailed further below, a portable pump301may be coupled to the port100to direct 10,000 PSI or more of pressure through the leak path110in order to confirm that the seal125is in proper working order. This is particularly beneficial because it allows for a way to test the seal125from an exterior location of the assembly101without requiring that the wellbore180be plugged and the more substantial undertaking of pressurizing the entire wellbore180above the plug.

Confirmation of the functionality of the primary seal125at the interface120means that concern over leakage of wellbore fluids from the wellbore180via the interface120during subsequent well operations may be assuaged. However, due to the configuration of the primary seal125and the fact that the pressure testing is directed at the seal125from an external location, an additional architectural feature is provided. Specifically, a secondary seal150is provided interior of the primary seal125and also at the interface120.

With added reference toFIG.2, as detailed below, because of the manner in which the primary seal125functions, this backup secondary seal150allows for an accurate read of the functionality of the primary seal125from the described pressure test. Namely, the use of the secondary seal150means that both an interior face250and an outer face275of the seal150are tested. Without the secondary seal150, the pressure testing may falsely indicate seal failure of a functional seal125due to lack of sealing at the interior face250which is not determinative of seal functionality.

Referring now toFIG.2, an enlarged view of the test port100and wellhead interface120is shown, taken from2-2ofFIG.1. In this depiction, the wellbore180, defined by the wellhead130and base140is apparent, immediately adjacent the interface120. Thus, concern over potential wellbore pressures directed at the interface120is apparent. It is along these lines that the primary seal125has been installed and set as illustrated. Setting aside the port100, leak path110and secondary seal150for the moment, the primary seal125is wedged into a primary groove450that is defined by the interfacing wellhead130and base140(seeFIG.4). In the embodiment illustrated, it is the outer face275of this seal125, sealing against the wellhead130and base140structures that provide the sealing at the interface120relative the wellbore180.

Returning to the test port100, it is possible that the application of test pressure through the leak path110in the wellhead130to the primary seal125would overcome the interior face250of the seal125even for a functionally set seal125. Thus, to ensure that the outer face275sealing is the feature tested by the application of the port pressure, the secondary seal150is provided. So, for example, in circumstances where fluid pressure from the test port100overcomes the interior face250, the presence of the secondary seal150assures that the pressure will merely be routed back to the outer face275of the primary seal125. Thus, so long as the outer face275is in sealing engagement with the wellhead130and base140, pressuring up to a predetermined level via the test port100is possible and the primary seal125will test as functional. Of course, if pressure is unable to build to the predetermined level, even with the backstop of the secondary seal150in place, it may mean that the outer face275is not maintaining the intended sealing and the primary seal125has not passed the pressure test.

It is worth noting that for the testing scenario described above, the pressure applied through the port100for testing is “predetermined”. So, by way of example, where the potential pressure expected in the wellbore180following completion is to be over about 5,000 PSI but below about 10,000 PSI, the predetermined pressure test may be to a level of 10,000 PSI. Thus, a primary seal125passing the test may be rated at 10,000 PSI and considered well suited for use in the given well. Of course, wellbore pressures near the interface120may be higher. Thus, along these same lines, it may be possible to utilize the exterior port100to confirm a rating of 30,000 PSI or more for the primary seal125.

Referring now toFIG.3, an overview schematic representation of an oilfield300accommodating the wellhead assembly101ofFIG.1at a well302. A host of conventional equipment350is shown at the wellsite, including a rig360to help support various installations. In the embodiment shown, a Christmas tree355accommodating various valves and other hookups has been installed at the wellhead130. Thus, the importance of ensuring proper internal sealing between the wellhead130and the base140is brought to mind.

In the embodiment shown, the wellbore180traverses a formation375potentially facing several thousand pounds of pressure in the vicinity of the wellhead101. Accordingly, pressure testing as described above may be achieved by use of a handheld, portable external pump301that may be hooked up to the external port100for testing. By way of comparison, a larger pump315and control unit330of a mobile equipment truck310may be left in place. There is no need to plug the wellbore180or pressure up the well302internally. Thus, there is also no need to spend 8-10 hours of test time devoted to such measures. Instead, an operator may simply hook up the smaller handheld pump301at the test port100and ensure that the internal seal (e.g. the primary seal125ofFIGS.1and2), is properly set. Once confirmed, the tree355and other installations may ensue and operations within the well302may safely proceed.

Referring now toFIG.4, an enlarged view of the primary seal125and an adjacent secondary seal150is illustrated taken from4-4ofFIG.2. In this view, the intentional leak path110is shown intersecting the primary seal125in a primary groove450defined by the wellhead130and base140at the interface120. It is also apparent that any fluid pressure supplied through the leak path110during testing as described above would be directed at both the interior face250and the outer face275of the seal125. As indicated above, sealing by the primary seal125may be particular to sealing at the outer face275. Therefore, to ensure that leakage past the interior face250does not serve as a false indicator of seal failure, the secondary seal150is provided at a location interior of the primary seal125at the interface120. Thus, so long as sealing is maintained at the outer face(s)275, pressure may be held and built up within the leak path110during testing as described. As a result, leakage through the interior face(s)250would not result in a failure designation for the seal125.

Referring now toFIG.5, a side and partial cross-sectional view of an alternate embodiment of a wellhead assembly101is shown, again employing an exterior test port100. In this embodiment, a tubular500such as a production tubular has been installed within the wellbore. Thus, the potential for a leak path from a failing primary seal125continues beyond the horizontal interface120and to a vertical interface between the installed tubular500and the structure of the wellhead assembly101that defines the wellbore180(e.g. the wellhead130and base140). As a result, backup sealing by a secondary seal may take place at locations of the vertical interface. Namely, as illustrated, backup sealing is achieved by an upper secondary seal525above the horizontal interface120and a lower secondary seal550below this interface120. Each secondary seal525,550of this embodiment is located at the vertical interface and secured by the tubular500.

For the embodiment ofFIG.5, the secondary seals525,550again achieve the function of preventing a false indication of primary seal failure during testing from the exterior port100should leakage through the leak path migrate past the interior face250even though successful sealing occurs at the outer face275. Once more, utilizing the vertical interface for the backup sealing means that the limited space of the horizontal interface120is not required. So, for example, where the size and space constraints of the horizontal interface120are such that an effective secondary seal may be difficult to manufacture or install, this backup sealing function may be moved to the more available space of the vertical interface.

Referring now toFIG.6, a flow-chart is shown summarizing an embodiment of testing a primary seal at an interface of a wellhead with an exterior test port. As indicated at620, the wellhead seal is installed at the interface that has the potential to serve as a leak path from the wellbore that is defined by the wellhead assembly. Therefore, in order to test the seal in a manner that does not utilize the wellbore itself, a fluid may be pumped through an external port of the assembly toward the seal (see640). Because the resulting fluid pressure is directed at the seal from an opposite direction of that of the wellbore, a backup or secondary seal may be utilized as indicated at660. That is, to prevent a false indication of seal failure, the backup seal may be utilized to prevent leak detection when the leak would be at a face of the seal that is not actually of concern in the real world environment of preventing a wellbore leak. Thus, as indicated at680, a true reading of test results based on the ability to pressure up through the exterior test port may be attained.

Embodiments described above provide a manner of testing a wellhead seal that avoids the more time consuming conventional techniques that require plugging and subsequent unplugging of the main wellbore. Thus, time, labor and material expenses may all be dramatically reduced. Once more, since the technique is applied externally, other aspects of installation are not impacted by way of closing off of the main bore. Thus, operators may be afforded a greater degree of flexibility in determining whether and when to proceed with other installation steps apart from testing of the wellhead seal.

The preceding description has been presented with reference to presently preferred embodiments. Persons skilled in the art and technology to which these embodiments pertain will appreciate that alterations and changes in the described structures and methods of operation may be practiced without meaningfully departing from the principle and scope of these embodiments. Furthermore, the foregoing description should not be read as pertaining only to the precise structures described and shown in the accompanying drawings, but rather should be read as consistent with and as support for the following claims, which are to have their fullest and fairest scope.