Wells – Packers or plugs – With central conduit and fluid port to space outside
Reexamination Certificate
2000-09-21
2002-08-06
Dang, Hoang (Department: 3672)
Wells
Packers or plugs
With central conduit and fluid port to space outside
C166S188000, C166S317000, C166S324000, C166S325000
Reexamination Certificate
active
06427773
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a tubing plug adapted for insertion into a tubing string for sealing the tubing string. More particularly, the present invention relates to a tubing plug providing a two-way fluid bypass and a one-way valve. Preferably, the one-way valve is pressure actuated by a flow of a fluid through the tubing plug.
BACKGROUND OF INVENTION
Retrievable tubing plugs are used in the oil or petroleum industry for temporarily isolating a portion of a tubing string contained within a wellbore. Specifically, the tubing plug is inserted within the tubing string at a desired downhole location in the wellbore for the purpose of temporarily plugging or sealing the tubing string, thus enabling completion or servicing operations to be carried out in the tubing string above the tubing plug. Typically, the tubing plug is run in and out of the tubing string using wireline equipment or fishing tools.
Conventional tubing plugs, which may also be referred to in the industry as blanking plugs, are designed as two-way plugs or seals. In other words, when the tubing plug is set in position within the tubing string, the tubing plug restricts or inhibits the flow of fluids through the tubing string across or about the tubing plug in both directions. The flow of fluids is inhibited through or across the tubing plug both externally and internally. The tubing plug is sealed internally or otherwise configured to prevent any internal fluid flow through the tubing plug. In addition, the tubing plug is sealed externally by sealing between the outer surface of the tubing plug and the inner surface of the surrounding tubing string to prevent any flow of fluid externally about the tubing plug.
However, it is preferable during the placement of the tubing plug in the tubing string to permit fluid to flow through or across the tubing plug to avoid a piston effect whereby the tubing plug pressurizes the fluid below it as it passes through the tubing string. Once the tubing string is in place at the desired location in the tubing string, the tubing plug is closed to permit the tubing plug to perform its plugging or sealing function in both directions.
Further, tubing plugs are preferably removable from the tubing string after use. However, if the pressure in the portion of the tubing string above the tubing plug is greater than the pressure in the portion of the tubing string below the tubing plug, difficulties will be encountered with the removal of the tubing plug from the tubing string. Conversely, if, the portion of the tubing string below the tubing plug has a greater pressure than the portion of the tubing string above the tubing plug, there is a tendency for the tubing plug, along with the wireline or retrieval tool, to be “shot” or “kicked” uphole by the pressure imbalance or differential during the removal process, resulting in wireline breakage, lost tools and other associated dam age and expenses. Thus, in order to facilitate the removal of the tubing plug from the tubing string, it is again desirable to be able to permit fluid to flow through or across the tubing plug in order to equalize the pressure above and below the tubing plug.
As a result, tubing plugs have been developed which provide a fluid bypass or bypass port which permits the flow of fluids across or about the tubing plug. These tubing plugs are typically referred to as “bypass tubing plugs.”
A first style of bypass tubing plug, such as that manufactured by Baker Oil Tools as Model “FSR”™ Bypass Blanking Plug Product No. 806-06, has an automatic bypass to permit pressure equalization across the tubing plug in both directions. The bypass is automatically held open by the running tool while the tubing plug is being lowered into the tubing string to permit a flow of fluid across the tubing plug. The bypass is automatically closed when the running tool is released to enable the tubing plug to perform its plugging function. The bypass is then reopened when the running tool is reconnected with the tubing plug to permit pressure equalization and a flow of fluid across the tubing plug in order to facilitate the removal of the tubing plug from the tubing string. Alternatively, pressures can be equalized across the tubing plug by breaking a secondary equalizing plug using a special tool imparting a downward impact.
A second style of bypass tubing plug, such as that manufactured by Baker Oil Tools as Model “FSG”™ Bypass Blanking Plug with Removable Mandrel Product No. 806-07, includes a “removable mandrel” or “equalizing prong” which is moved axially either to close off a bypass port in the tubing plug or to open the bypass port to permit fluid flow and pressure equalization in both directions across the tubing plug. Typically, the mandrel has three positions. A first lower position of the mandrel results in the bypass port being open and is used to permit a flow of fluid through or across the tubing plug during lowering of the tubing plug into the tubing string. A second intermediate position closes off the bypass port during use of the tubing plug to facilitate its plugging function. A third upward position results in the mandrel being removed from the tubing plug to open the bypass port once again to permit a flow of fluid through or across the tubing plug in order to facilitate pressure equalization.
As indicated, upon closure of the fluid bypass or bypass port in each of these tubing plugs, the tubing plug substantially seals the tubing string and prevents the flow of fluid through or across the tubing plug. However, it may be desirable in some circumstances to be able to pump a fluid through the tubing string following the placement or landing of the tubing plug within the tubing string.
Further, these tubing plugs typically provide a relatively small fluid bypass or bypass port therein. As a result, the fluid bypass or bypass port tends to be susceptible to plugging or blockage, particularly when used in wells having high viscosity fluids or experiencing the settling of significant wellbore debris in the tubing string. Plugging of the bypass or ports may cause difficulties whenever a differential pressure is experienced in the tubing string across the tubing plug, particularly during the removal of the tubing plug from the tubing string.
For example, U.S. Pat. No. 4,586,569 issued May 6, 1986 to Hyde describes a retrievable fluid control valve including, from top to bottom, a valve housing, a bypass means and a sealing means for seating in a seating nipple of a tubing string to seal the tubing string annulus. A cavity within the valve housing communicates with a fluid passageway extending downwards through the bypass means and the sealing means. Further, an upper port is provided through the valve housing for communicating fluid between the annulus (above the sealing means) and the upper end of the cavity. A movable valve member blocks the passage of fluid between the annulus and the upper end of the cavity. When a pressurized fluid is pumped down the tubing string annulus (above the sealing means), the movable valve member is moved upwardly away from the upper end of the cavity to permit fluid to flow through the upper port and then downwardly through the cavity, the bypass means and the seal means. The bypass means is normally closed and includes a lower port for communicating fluid between the fluid passageway and the annulus (above the sealing means).
To remove the fluid control valve of Hyde from the tubing string, the downward flow of the pressurized fluid is interrupted. As a result, the movable valve member is moved downwardly towards the upper end of the cavity to block the passage of fluid through the upper port. Further, the lower port in the bypass means is opened to permit fluid to bypass the sealing means by flowing from the fluid passageway to the annulus (above the sealing means).
However, no mechanism is provided by Hyde for clearing or flushing the lower port in the event of blockage. Thus, there may be difficulties in equalizing a differential pressure in the tubing string above and be
Dang Hoang
Kuharchuk Terrence N.
Lonkar Services Ltd.
Rodman & Rodman
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