Wells – Submerged well – Connection or disconnection of submerged members remotely...
Reexamination Certificate
2000-03-31
2001-05-29
Lillis, Eileen D. (Department: 3673)
Wells
Submerged well
Connection or disconnection of submerged members remotely...
C166S065100, C166S342000, C166S360000, C166S368000, C439S201000, C439S310000, C403S002000
Reexamination Certificate
active
06237690
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a connector assembly and to a wellhead assembly provide with such a connector assembly.
2. Description of the Related Art
It is known from U.S. Pat. No. 5,558,532 to provide an underwater wellhead assembly comprising a vertically oriented tubing hanger dispose in a spool body, and a connector assembly comprising a first connector part in the form of a plug body and a second connector part in the form of a receptacle for the plug body. The receptacle is arranged in the tubing hanger with its axis horizontal and the plug body is mounted by a carriage horizontally reciprocatable between a forward position in which the connector parts are connected and a retracted position in which the connector parts are disconnected. In the retracted position the plug body is fully withdrawn from the tubing hanger so that it is then possible to remove the tubing hanger, together with the receptacle, vertically from the spool body and to take it to surface for repair or modification. Each time the tubing hanger is returned to the spool body it has to be accurately located so that the connector parts are in alignment with each other. However, because of manufacturing tolerances exact alignment is not always achieved, and there may be a lateral offset between the longitudinal axes of the connectors (lateral misalignment), or an angular misalignment between the axes, or a combination of the two. If there is misalignment, there may be a problem in that the plug body cannot properly engage the receptacle during the forward movement of the carriage.
To deal with this problem, we have previously proposed a mounting arrangement for the plug body on the carriage which allows lateral movement of the plug body relative to the carriage, and limited pivotal movement about a vertical axis only. This mounting arrangement consists of a pair of radially outwardly projecting circumferential flanges on the plug body, the flanges being longitudinally spaced from each other, and a split ring on the carriage projecting radially inwardly into the space between the flanges. An O-ring is disposed around the plug body radially inwardly of the split ring. The plug body is able to move laterally relative to the carriage, if necessary to correct lateral misalignment as it engages in the receptacle, by deforming the O-ring. In addition, because the split ring projects into the space between the plug body flanges at the top and the bottom of the plug body, but not at the sides, a small amount of pivotal movement about a vertical axis is possible to correct angular misalignment.
Such a mounting arrangement works well. In some circumstances, however, for example when the receptacle is arranged with its central longitudinal axis tangential to a circle about the central vertical axis of the tubing hanger (rather than radially of the tubing hanger), it is necessary to design the plug body and mounting with a relatively long portion of the plug body projecting forwardly of the mounting. The weight of the forwardly projecting portion creates a couple which increases friction at the mounting and thus restricts its ability to allow the plug body to move relative to the carriage during correction to correct any misalignment. Another possible cause of restricted movement at the mounting is the presence of sand or other debris, which may create a problem even if the forwardly projecting portion of the plug body is relatively short.
According to a first inventive aspect there is provided a connector assembly comprising first and second connector parts, the first connector part being mounted by a carriage reciprocatable between a forward position for connecting the connector parts and a retracted position for disconnecting the connector parts, wherein the mounting of the first connector part by the carriage is such as to permit pivoting of the first connector part in response to a force in any lateral direction on the first connector part and acting at a location forward of the mounting.
If there is misalignment of the connector parts when disconnected, as they are brought into engagement the first connector part can align itself with the second connector part. The pivotal mounting of the first connector part enables the correction in alignment to be achieved. Thus any tendency for the first connector part to become jammed during the connection process as a result of misalignment is reduced.
The lateral force may for example be horizontal or vertical, both of these being lateral to the longitudinal axis of the first connector part, or a combination of the two, depending on the direction of misalignment to be corrected. As discussed above, there may be a tendency for the first connector part to tilt downwardly, when disconnected, due to the weight of the portion of the first connector part projecting forwardly of the mounting. In such a situation, since the mounting can permit downward pivoting about a horizontal axis, its functioning will not be impaired by increased friction, as in the known mounting system. The downward tilting can be reversed as the first and second connector parts engage with each other and a correcting lateral (i.e. upward) force is applied by the second connector part to the first connector part.
Preferably, one of the connector parts is a plug body and the other a plug receptacle. In order to help correct misalignment during the forward stroke of the carriage, the plug body may have an externally chamfered nose whilst the plug receptacle may have an internally chamfered mouth. If there is misalignment, the chamfers allow the nose to engage in the mouth during the carriage forward stroke. It is preferred that the first connector part is the plug body and that the second connector part is the plug receptacle, although the reverse arrangement is possible.
The connection to be made may be electrical (such as low power for gauges or other instrumentation or high power for powering equipment such as a down hole pump) or optical or a mixture of the two. A preferred connector, having first and second connector parts for use in the connector assembly, is described in GB-A-2 192 316.
Another cause of an initial angular misalignment of the first connector part, in addition to the downward tilting mentioned above, may be an eccentric load applied by a cable extending from the rear of the first connector part. In many cases, the problem of an initial angular misalignment is overcome, as the desired final orientation of the first connector part can be achieved by the application of a correcting lateral force by the second connector part as the two are brought into engagement. The pivotal mounting enables this to be achieved. However, in situations where the length of the first connector part projecting forwardly of the mounting is relatively long (as in the case for example of a non-radial entry to a tubing hanger mentioned above), there is a corresponding increased effect of any angular misalignment at the front end of the first connector part, where it first engages with the second connector part during the forward stroke of the carriage. In an extreme case, it may not be possible to achieve connection.
Preferably, therefore, the mounting is such as to centre and align the first connector part along a predetermined axis when the carriage is in the retracted position. Such an arrangement ensures that the first connector part is in the proper orientation relative to the carriage, despite any forces applied to the first connector part by its own weight or a cable connected to it. There may of course still be misalignment between the first and second connector parts, caused by misalignment of the carriage relative to the second connector part, but this will normally be small and readily correctable during the connection process.
Apart from an angular misalignment relative to the axial direction there may be a lateral offset and therefore preferably the mounting of the first connector part is such as to permit lateral movement of the first connector part
Alix Yale & Ristas, LLP
Lee Jong-Suk
Lillis Eileen D.
Tronic Limited
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