MXPA05011263A - Method for confirming the integrity of a seal system within a subterranean well conduit christmas tree valve assembly. - Google Patents

Abstract

Method and apparatus are disclosed for confirming the integrity of a seal system extending between a conduit disposed within a subterranean well and a surface or top Christmas tree assembly such that the confirmation steps do not adversely thereafter effect the sealing integrity of the system when exposed to high pressure and/or temperature environments.

Description

METHOD FOR CONFIRMING THE INTEGRITY OF A SEAL SYSTEM PLACED INSIDE A CHRISTMAS TREE VALVE ASSEMBLY OF A DUCT IN A UNDERGROUND WELL FIELD OF THE INVENTION This invention relates to an apparatus and method for confirming the integrity of a seal system placed inside a Christmas tree of an underground well and one or more conduits, such as production tubing and / or casing. placed in that place.

BACKGROUND OF THE INVENTION The production and coating pipes are placed inside an underground well after drilling, rehabilitation or completion work. The length of the casing pipe having the largest diameter is first introduced through the upper part of the well through which a section of smaller diameter casing pipe is also introduced as an extension below the lower end of the casing pipe. longer diameter liner and secured to said end by means of an auxiliary liner fastener. Then the series of duct sections of the casing can be telescopically and concentrically placed inside the well, depending on the depth of the well and the location of the production zone or zones. In general, the smaller diameter casing section will have a section of the production line inside it. The upper ducts are secured on the surface of the well through a "Christmas tree" which is a valve system that holds the production and coating ducts in a closed relationship and with valve mechanisms to control the flow of the fluid through thereof . Conventional methods of testing the well head and Christmas tree cavities defined between the Christmas tree box and the outside diameter of one of the duct elements employ the use of water fluids and oils. The temperatures encountered during the high pressure and high temperature well flow conditions have the potential to heat those fluids to a point where fluid expansion can potentially collapse the metal sealing sleeves and the elastomeric seals. In addition, the use of water can eventually cause corrosion of the metal parts, and the use of oil can eventually degrade the elastomers.

However, these drawbacks have already been solved by US Pat. No. 6, 237, 689 Bl in favor of Mr. Louis j. Wardlaw, same applicant for this invention. In said patent a method is provided for confirming the integrity of the seal between grooves of a seal system having elements placed in a cavity between the underground well conduit, such as casing or production pipe, and an inner sealing surface of a Christmas tree valve assembly. The method includes the steps for first introducing through a sealable opening of an injection path communicated with the cavity and into the cavity between the elements of the seal, an inert gas combined with a gaseous hydrocarbon marker such as helium, freon or propane to detect the presence of inert gas outside the assembly of the Christmas tree. An apparatus for confirming the integrity of the seal system inside the Christmas tree is also provided, with means such as an injector extending from a line communicated with a compressor and a pump being introduced into the cavity and between the seal elements for injecting through the injection path into the cavity a first inert gas combined with the hydrocarbon label.

However, it has been detected that the introduction, the inert gas containing a gaseous hydrocarbon marker, under pressure inside the injection path communicated with said cavity, considerably reaching, generally, up to around 1406 kg / cm2 (20,000 psi) is insufficient, this due to the working conditions and the well, reason why based on proper work tests it was determined that said pressure must be between 1406 kg / cm2 to 2109 kg / cm2 (30,000 psi) SUMMARY OF THE INVENTION A method is provided to confirm the integrity of the seal between slots of a seal system under working conditions having elements placed in a cavity between the well conduit underground, such as casing or production pipe, and an interior sealing surface of a Christmas tree valve assembly. The method includes the steps for first introducing through a sealable opening of an injection path communicated with the cavity and into the cavity between the elements of the seal, an inert gas combined with a gaseous hydrocarbon marker such as helium, freon or propane to detect the presence of inert gas outside the assembly of the Christmas tree. The pressure inside the cavity is increased to a first predeterminable amount. Then the absence of the marker in the immediate atmosphere outside the Christmas tree is verified. If the verification step confirms the absence of the gaseous hydrocarbon marker immediately to the cavity, the pressure within the cavity is decreased to a second predeterminable amount, which is less than the first predeterminable amount and then the injection path is closed. The invention also provides an apparatus for confirming the integrity of the seal system inside the Christmas tree, with means such as an injector extending from a line communicated with a compressor and a pump being introduced into the cavity and between the seal elements. for injecting through the injection path into the cavity a first inert gas combined with the hydrocarbon label. The means includes a compressor and / or pump that is used to apply pressure inside the cavity to the inert gas and hydrocarbon label a, a predeterminable amount and, once the absence of the marker in the immediate atmosphere outside the Christmas tree, are used to decrease the pressure inside the cavity to a second predetermined amount that is less than the first predetermined amount.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1A is a partially vertical, partial, exterior cross-sectional view of a Christmas tree assembly of an underground well showing the cavity between the sealing elements and an injector extending to a line and a compressor / pump assembly for the introduction of an inert gas and a hydrocarbon marker.

FIGURE 1B is a view similar to FIGURE 1A showing the sealing means of the Christmas tree extending between the elongated elements of the pipeline arranged concentrically inside - of the Christmas tree and inside the box of the Christmas tree.

DESCRIPTION OF THE PREFERRED MODALITIES FIGURE 1A shows a Christmas tree assembly 100 which generally consists of a shut-off valve assembly 101 having an outer box 102 through which a sealing block is placed securing the upper end of a production pipeline 104 securely threaded to block 103 on threads 105 and secured by means of a sealing sleeve 106 to housing 102. A conventional wheel valve 107 is positioned through the closing valve assembly 101 to manipulate valves between positions open and closed. The Christmas tree assembly 100 has at its upper end a conventional pressure gauge 108 and a needle valve 109 placed downwardly and in communication in that manner and, in turn, secured to a tree top adapter 110 which is the upper end of the housing 102 of the shut-off valve assembly 101. The sealing block 103 has a series of first seal elements 111 A and 111B positioned radially around the outside of the upper end of the sealing block 103 with in order to secure the seal of the block 103 to a smooth inner wall surface 112 of the block 103. Likewise, a second lower seal assembly 113 is positioned circumferentially around the outside of a lower portion of the sealing block 103 for the sealing gear around the elongated portion of the inner surface 112 A of the box 102. The elements of the seals 111 A, 111 B and 113 bridge a defined cavity 114. between them and inside the box 102. The dotted line 115A in Figure 1A represents an injection path extending between the upper end of the cavity 114 and an injector 115 which, in turn, is secured to a end thereof to a gas line 116 communicated with a compressor and pump assembly 117, which may be portable, driven by gas or electricity. A purge valve 118 is connected to line 116 to purge the pressure subsequent to the absence check of the hydrocarbon marker around the Christmas tree. After removing the injector 115, a threaded sealing cap, such as the cap 118, can be threaded for a secure seal to the box 102 to ensure the integrity of the seal inside the cavity 114. Turning to Figure IB, we find components with similar numbering . Figure IB illustrates a series of additional seal assemblies 119 A and 119 B that define a cavity 120 between them externally and surround the production line 104. In addition, the Christmas tree assembly 100 includes below the cavity 120 a similarly positioned seal member 121 A and 121 B which provides the sealing means inside the Christmas tree assembly 100 to engage around the outside of a casing conduit 122 arranged concentrically around the outside of the production pipeline 104.

When the components of the production and coating pipe are joined at the top of the well, the assembly of the Christmas tree 100 is in place around the production pipe 104 secured at its upper end by means of the threads 105 sealing block 103. The sealing sleeve 106 secures the sealing block 103 inside the box 102 to hang the production line there. In order to ensure that the seal elements 111 A, 111 B and the second seal assembly 113 have required sealing integrity in relation to the interior surface 112 A in the box 102, the cover 118 is removed and the injector 115 it is positioned relative to the injection path 115 A, and the injector 115 extends to line 116 which, in turn; is placed in relation to a combination of the compressor and pump assembly 117. The compressor and pump assembly 117 is used to introduce the combination of an inert gas with a gaseous hydrocarbon label through line 116, injector 115 and in the path from the injector 115 A to the cavity 114. 'Any known inert gas can be used in conjunction with this invention. By "inert" is meant any gaseous compound that will not react with the marker gas in such a way that the marker can not be detected during the test, as well as being safe and non-hazardous when used around Christmas trees from gas wells . Preferably nitrogen is used. The gaseous label must be compatible with the selected inert gas and must have the ability to be detected by its odor or by the use of a conventional gas detection device sensitive to predeterminable quantities of a particular marker. Any hydrocarbon-based gaseous label, such as freon, hydrogen, helium, or any other chlorofluorocarbon constituent or gaseous component containing halogen, may be used. As the gas and marker are introduced under pressure into line 116 into cavity 114, the pressure inside the cavity increases considerably, typically reaching between 1406 kg / cm2 (20,000 psi) to 2109 kg / cm2 ( 30,000 psi). The absence of the marker in the immediate atmosphere outside the Christmas tree is verified using a portable verification device of construction and availability known to those skilled in the art or by detection thereof through the human nose. If the absence of the marker is verified, the pressure inside the line 116 and the cavity 114 are purged through the purge valve 118, so that the pressure inside the cavity 114 is approximately 1.033 Kg / cm2 (one atmosphere ). The injector 115 is removed in relation to the path of the injector 115 A and the threaded sealing cap 118 is secured to seal the outer end of the injector path. Of course, if the absence of the marker is not verified and, in fact, the component of the marker is detected, the box 102 of the assembly of the Christmas tree 100 can be removed or opened, to allow the replacement of the respective stamp assemblies, or to take another kind of remedial action. Regardless of the presence or absence of the marker in the atmosphere around the outside of the Christmas tree, the use of this invention will result in the original seal method, or in the method of repaired or replaced stamps that have not been subsequently exposed to corrosion of water or oil or the like found as a result of the use of previous techniques. During the method described above, the pressure will normally be maintained at the first level increased and preselected for a period of about one hour. Then, the pressure is reduced and the test gas is vented at atmospheric pressure and the cavity and injector line are sealed. It will be noted that the use of this method leaves the cavities between the elements of the seal assembly filled with an inert gas at atmospheric pressure, thereby allowing the gas to expand during the conditions of the well flow but still within the acceptable pressure limits of the sealing mechanisms. Although the invention has been described in terms of specified embodiments that are indicated in detail, it should be understood that it is done by way of example only and that the incorporations and operating techniques will be obvious to those skilled in the art as a result of the revelation. Therefore, the modifications that are projected can be made without departing from the spirit of the described invention.

Claims (1)

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the property described in the following claims is claimed as property. CLAIMS

1. A method for confirming the integrity of the boundary of a sealing system by having the elements placed in a cavity between an underground well conduit and an inner sealing surface of a shaft valve assembly. Christmas, comprising the following steps: a) entering through a sealable opening an injection path communicated with said cavity, inside said cavity and between said seal elements a first inert gas containing a gaseous hydrocarbon label; b) increasing the pressure within said cavity to a first predeterminable amount; c) verify the absence of said marker in the atmosphere immediately outside the assembly of the Christmas tree valve; d) decreasing the pressure within said cavity to a second predeterminable amount less than said first predeterminable amount; and e) sealing said opening of said injection path. WHICH CHARACTERIZES BECAUSE it also comprises the step of: f) introducing the inert gas containing a gaseous hydrocarbon marker, under pressure into the injection path communicated with said cavity, considerably reaching, in general, between 1406 kg / cm2 (20,000 psi) up to 2109 kg / cm2 (30,000 psi) after step a).