US2478628A - Testing casing heads - Google Patents

Description

1949. c. HANSEN 2,478,628

TESTING CASING HEADS Filed Jan. 27, 1947 3 Sheets-Sheet 1 lflvenrori Charles Hansen 1- m M momeq 9, 1949- c. HANSEN TESTING CASING HEADS 3 Sheets-Sheet 2 Filed Jan. 27, 1947 Fiq. 3

Charles Hansen Aug. 9, 1949. c. HANSEN 2,478,628

TESTING CASING HEADS Filed Jan. 27, 1947 3 Sheets-Sheet s F'lq. 5 I q- L JnvenTox-Z Char-\es Hansen H his momma Patented Aug. 9, 1949 UNITED STATES PATENT OFFICE TESTING CASING HEADS Charles Hansen, Ventura, CaliL, minor to Shell Development Company, San Francisco, Call! a corporation of Delaware Application January 27, 1947, Serial No. 724,644

2 Claims.

ous strings of casing which extend into the well.

When the well is completed these fittings comprise the casing head assembly including that part which is commonly known as the "Christ'- mas tree. Although considerable care isexercised in connecting the various fittings and although each component part of the assembly is always previously tested to a pressure in excess of the rated working pressure, there is no assurance until the well actually produces that the assembled fittings installed on the well head will withstand the working pressures without leakmg. I

In this connection, it is not uncommon for leaks to develop in the casing head assembly at the packing, sealing rings, screw threads and/or other connections which are made up or assembled at the well. discovered until after the well had been allowed to produce. Such leaks are not only hazardous but have caused the loss of numerous wells. Even though the leak can be repaired after the well has been brought in, it is often necessary to again Such leaks, however, are not usually set up the drilling machinery and to kill the well before the repairs can be made. This procedure involves considerable expense and may result in damaging the wells production.

It is therefore the primary object of this invention to provide a method for testing a casing head assembly for leaks as it is being installed on the well.

Another object ofthe present invention is to provide an apparatus adapted to be positioned at various locations within the assembly and to seal ed the various test areas.

A further object of this invention is to provide a simple, inexpensive testing apparatus of sturdy construction which can be easily and quickly installed or removed from the casing head and which is capable of withstanding the high testing pressures.

A still further object is to provide a method whereby various parts of the casing head assembly may be tested after they have been installed at the well.

These and other objects of this invention will be understoodfrom the following detailed description of the method and the preferred em- 2 bodiments of the apparatus of the present invention as shown in the accompanying drawings wherein:

Figs. 1, 2, 3 and I are diagrammatic views,

' partly in cross-section, of the present testing apparatus positioned in diflerent parts of the casing head assembly. I

Fig. 4 isa view of a retrieving tool used to remove part of the testing apparatus from the casing head.

Figs. 5 and 6 are diagrammatic views partly in cross-section of packing elements forming part oi casing headstructures tested according to the present method.

Figures 8, 9 and 10 are modified forms of the testing mandrel.

In describing the present invention, reference is made to the attached drawings which show a typical well multi-string installation such as employed in high pressure wells requiring three strings of casing. It is to be understood that modifications or alterations can be made in the testing method and apparatus of this invention to permit adaptation to systems and types of well control installation other than that shown.

In setting up the component parts of this assembly at the well, installation of the entire well head assembly is not completed at one time, but is made progressively as the drilling of the well advances. In Fig. 1, for example, the lowermost casing head base unit I I is attached to the upper end of the large (for example, 13%") outer casing II at the time said casing is run and cemented in the well as shown at IS. The attachment of the casing I! to the base unit H is generally made by welding as shown at l3 and I4. After attachment of. the base unit ll, continued drilling through the large casing I! may be accomplished in a manner well known in the art by flanging to'the upper flange face It of the base unit II, a drilling riser (not shown) comprising blow-out preventer equipment, now outlets, etc.

When the well is in condition to receive a smaller size (for example, 9%) casing ll, the latter is usually run through the drilling riser and cemented in the well. Afterwards, the drilling riser is removed from the well, permitting the insertion of slips I8 and a spider IS in the base unit I l for supporting the casing I1. The casing I1 is then cut oil at its upper end, at a point 20 as shown, and an annular fluid-tight means such as the packing assembly 2|, containing packing 98, isinstalled which seals of! the annulus 22 between the casings l2 and I! at the surface of the well. A casing spool is then flanged to the base unit II, for example by means of bolts 48, as illustrated, which retain the Packing assembly 2| in place. The upper flange face of the base unit H, the lower flange face of the casing spool 23 and both sides of the flange of the packing element or assembly 2| are all equipped with annular grooves, as shown at 24, which are adapted to receive annular fluid-tight means such as sealing rings 25 and 26 which are preferably metallic sealing rings. The casing spool 23 is provided with threaded outlets such as 21 and 28, one of said outlets being adapted to receive a bull plug 29 and the other a nipple 30 of a high pressure valve 3| as will be described hereinbelow. The base unit II is also provided with similar threaded outlets 32 and 33 adapted to receive the testing equipment but normally plugged shut. All parts which have been described as being installed on the well thus far, except the drilling riser, are permanent, being retained in assembly during the production life of the well.

It should be particularly noted that all of the connections made at the well in assembling the forenamed parts are susceptible to leakage. It istherefore highly desirable to test these vulnerable points of possible leakage at the time of installation and before drilling operations are resumed. This object can be accomplished by employing the means and method of the present invention.

The testing apparatus used in making this test is shown in Fig. 1. The equipment comprises a tubular testing mandrel 34, a gage 35, and a conduit such for example as a flexible hose 36 to which is connected a conventional hydraulic pump (not shown). The testing mandrel 34 is utilized in this invention to seal off certain sections or points of the casing head assembly to be tested and to prevent the longer mud-filled inner casings from being subjected to the test pressures. The inner casing is usually considerably longer than any of the outer casings and is usually subjected to greater pressures due to the greater static head of the drilling fluid within the casing. To expose this casing to an additional test pnessure might cause a rupture in said casing.

As can be seen in Fig. 1 the testing mandrel 34 comprises an assemblage of parts which are re-' lated and function in the following manner. The testing mandrel 34 is provided with an inner sleeve 31 having its lower end threaded to receive the shoulder stop nut 38 and its upper end threaded to receive the adjustment nut 39. Slidably mounted on the outside of the sleeve 31 above the stop nut 38 is a cylindrical lower packing element 49 and its glands or abutments 95 and 96, a spacer sleeve 4|, an upper packing element 42 and its glands 45 and 91, and a companion flange 43. These elements are held in place on the sleeve by the adjustment nut 39. A becket 44 is attached to the companion flange 43 to facilitate the handling of the testing plug or mandrel 34 when inserting it or removing it from the well control assembly.

In installing the test mandrel 34, the becket 44 is secured to a catline and the mandrel, with the packing adjustment nut 39 in the unloosened position, is lowered into place, as shown in Fig. 1, until the mandrel is supported by the lower ring gland 45, of upper packing element 42, in the tapered bore 49 of the casing spool 23. Following the seating of the testing mandrel 34 in the well control assembly, flange bolts and nuts 41 are 4 installed and tightened. The adjustment nut 39 is then tightened by rotation, which causes the upper and lower packings, 42 and 4!] respectively, to be compressed into sealing engagement with the bore.46 of the casing spool 23 and the bone of the casin respectively.

The pressure gage is then connected, as shown in Fig. 1, to the high pressure valve 3| and a flexible hydraulic hose 38 is installed to apply the pressure of a hydraulic pump to the outlet 28 of the casing spool .23, while the other outlet 2'! is closed by a bull plug 29. Hydraulic pressure is then applied through the side outlet 28 to the interior of the well control hook-up. This pressure, which is confined between the packing elements and 42 of the test mandrel 34, is thus applied to the sealing ring 26, the packing assembly 2| and the threaded connections of the side outlets 21 and 29 to test their ability to hold pressure.

A falling pressure as denoted by the readings of the pressure gage 35 indicates the presence of any leak. Repairs can then be made to the casing head before any more of it is assembled. The packing assembly 2| and the sealing ring 25 may be tested for leaks before orafter installation of the testin mandrel 34. The high pressure valve 3| is for this purpose transferred from outlet28 to outlet 32 in the base unit while the other outlet 33 is closed by means of a plug identical with plug 29. Hydraulic pressure is then applied as describedabove through the side outlet 32 to the annulus between the casings l2 and I! which is closed at the upper end by the packing assembly 2| and the sealing rin 25 and at the lower end by liquid standing in the well. This pressure is applied to the packing assembly 2|, the metallic sealing ring 25 and the threaded connections of the casing outlet vents 32 and 33, thus testing these seals for possible leaks.

When considerable trouble is encountered with the seal formed by the packing in the packing element 2|, it has been found advantageous to employ a packing element 49, such as shown in Fig. 6, having a lantern ring 50 located between rings of packing 5| and 52 which form the seal against the casing II. A conduit 53 leads from the lantern ring to the outside of the packing element, said conduit being normally closed by a 50 valve 54. Thus when pressure is applied through outlets 21 or 32 in order to test metallic sealing ring 26 or 25, the packing assembly 49 may first be tested by opening the valve 54 and noting any drop in test pressure by the gage. Any testing 55 fluid leaking past the packing 5| or 52 will have access to the outside through the lantern ring 59, conduit 53 and the open valve 54. After the packing assembly has been tested for leaks the valve 54 is closed while the sealing rings are tested. Should leaks occur at any of the forementioned points or at other places, repairs can be made and the assembly retested before reflanging the drilling riser for further drilling.

If the test is satisfactory, the testing mandrel 34 is removed after first loosening the adjustment nut 39 by rotation. The gage 35 and the flexible hose 38 are also removed. The drilling riser (not shown) is then flanged to the upper end of the casing spool 23 for continued drilling and for running and landin a smaller inner casing 55.

After the smaller (for example '7) casing 55 has been run and cemented in the well and the drilling riser has been removed, the casing 55 is,

said casing and the bore 48 of the casing spool 23.

The tubing-head spool 59 is then flanged in place above packing assembly 51 after the sealing rings 58 and GI, similar to rings 25 and 26, have been placed in the annular grooves of the flange faces, as shown. These parts arealso part of the permanent installation and inasmuch as they are exposed to the full pressure of the well, they must likewise be tested before the well is brought into production.

To test the lower sealing ring 60 and the packing assembly 51 for leaks, pressure is applied as before through the conduit 28. Other points besides the lower sealing ring 60 and the packing assembly 51 will also be subjected to this test pressure, but since they have previously been tested, any drop of pressure indicated by gage 35 can be due only to failure of the elements 60 or 51. If desired, a lower test pressure may be applied in this and subsequent tests as the remaining seals usually do not encounter the abnormal high pressures that are sometimes present before the inner string of casing is landed.

To test the upper sealing ring 6! a testing mandrel is provided which may be identical or similar to the one previously described, or may have certain modifications in order to adapt it for use with the component parts of a particularhead structure being tested. For example, the testing mandrel 62 may have slid-ably mounted thereon a plug 53 provided with packing 65 which seats in the upper tapered bore 64 of the tubing-head spool 59. Longitudinal adjustment is provided between the mandrel 62 and the plug 63 by means of a-right and left-hand threaded inter-connecting nut 66. A sleeve 61 is slidably carried by the mandrel 62 to engage the lower face of the plug 53 and also the upper end of the packing gland 68. The upper gland 68 and the lower gland 69, as well as the packing 18 are all arranged to slide on the mandrel 62 and are of such peripheral measurement as to closely fit the bore of the easing 55. A nut 1| is threaded to the lower end of the mandrel to retain the parts slidably mounted thereon.

The testingmandrel 82, in assembly, is lowered into the well control hook-up, to the position as shown in Fig. 2, and isretained therein by the hold-down screws 12. the latter being a part of the tubing-head spool 59. The lower packing is expanded and sealed off inside the casing 55 by rotational adjustment of the nut 86. When thus installed, the hydraulic pump, together with the gage 35, is connected to one of the two side outlet I valves 13 in the same manner as has previously been described for testing the installation of the larger casing l1. Hydraulic pressure is thus applied through either side outlet 14 or 1-5 to the interior of the well control hook-up between the test mandrel packings 65 and 10. This pressure tests the effectiveness of the seals at such vulnerable points as the upper sealing ring 6|, the v packing assembly 51 and the flange connections 16 and 11, before subjecting them to well pressure.

Referring to Fig. 3, after effecting the test described above, the drilling riser is mounted on the upper flange face of the tubing-head spool 59, drilling operations are completed and the well is tubed. After the tubing 18 has been run and landed and the drilling riser removed, the Christmas tree, as diagrammatically repre- .6 sented in general by numeral 19, is installed, preparatory to bringing the well intoproduction. The installation of the Christmas tree" usually necessitates the assembly of several subassemblies, as it is diflicult or impossible to transport and install a relatively large and complicated Christmas tree in one complete unit. The connections which fasten these sub-assemblies, and

' particularly the connection between the tubinghead spool and the Christmas tree," are sealed by gaskets, sealing rings or other fluid-tight means, and are susceptible to leakage if improperly installed. 5

The present invention also provides a method and apparatus for testing the effectiveness of all such last-mentioned connections before the well is brought into production. The testing mandrel for making this test may in this case be modified to a form such as a plug 80 shown in Fig. 3. The lower end of the plug 80 is provided with a packin 8|, preferably of a rubber-like material, which seals off the tubing 18 at its upper end. An enlarged shoulder 82 is formed on the plug 88 so as to engage the shoulder bore 83 of the tubing suspension plug 84, the latter being attached to the upper end of the tubing 18 and seated in the tapered bore 64 of the tubing-head spool 59 to support the tubing 18 and to pack it ofl inside the tub ng-head spool. A fishing neck 85 provided with radial pins 9| extendsupward from the enlarged shoulder portion 82 of the plug 89 to facilitate its removal following the completion of the test.

The test plug 80, at the operator's discretion, may be positioned in the upper end of the tubing 18 before the Christmas tree I9 is installed, or may be passed down through the central stem 85 of the tree by means of a retrieving tool 81 (Fig. 4) following the installation of the tree.

Whatever method is selected, the test plug 88 is positioned, as shown in Fig. 3, anda gage 88 and a flexible hose 89 are connected at any convenient point on the tree 19. The hydraulic pump (not shown) is then connected to the free end of the flexible hose 89 and the entire tree 19, as well as actual well pressure is introduced. Repairs, as

needed, can be made before bringing the well into production. v

Following the final operation of testing, the test plug is removed by means of the retrieving tool 81, the lower end of which is pro vided with slots 90. The retrieving tool is lowered in through the tree 19 and is caused to en age the pins 9! of the test plug 80 with the slots 90 to remove the test plug 80 from the tubing 18. After replacing the top flange through which the retrieving tool was removed, the assembly is in condition to permit the well to be brought into production with the assurance that all connections are pressure-tight.

Although the use of three different types of test mandrels or plugs 34, 62 and 80 is shown 'in the method of testing hereinabove described,

it is to be understood that this is done only for the purpose of showing the adaptability of this method to the use of different types of testing equipment. It can readily be appreciated that the test plug 80, that is used when testing the by one similar to test mandrel 34 which in turn could be replaced by a test plug.

It is also realized that many diflerent variations of the testing method are possible depending upon the equipment being used and tested in assembling the well head control system. For example, the method of testing could be shortened and simplified considerably if a flangeless packing assembly 93, as shown in Fig. 5, is used instead of the flanged type packing assemblies 2| and 51 previously described. Use of this type of assembly having no flange would eliminate one sealing ring and would leave only one ring 94 to be tested for each packing assembly used. Many types of packing can be used in both the packing assemblies and packing elements of the test mandrels. In the latter case however a resilient material, such, for example, as rubber or rubberlike material is the preferred form.

Since some types of casing head assemblies do not have the necessary outlets (21, 32 and 14) b which the test pressure may be applied to the seals and packing being tested, a modified form of the testing mandrel 34 may be used, such as one shown in Figs. 8, 9 or 10. These testing mandrels all possess a means by which the hose 36 from the hydraulic pump (not shown) may be attached directly to the mandrel so that the test pressure is applied through the mandrel to the test zone between the packing elements.

As can be seen in Fig. 8, the testing mandrel I00 is provided with an inner sleeve IOI having its lower end threaded to receive the shoulder stop nut I02 and its upper end threaded to receive the adjustment nut I03. Slidably mounted on the outside of the sleeve I 0| above the stop nut I02 is a lower packing element I04, a spacer sleeve I05, an upper packing element I06 and a companion flange I01. ,A fluid passageway I08 is formed longitudinally in the wall of said inner sleeve IOI so that its lower end communicates with an aperture I09 in the spacer sleeve I05. The upper end of the fluid passageway I08 is adapted to receive the test gage 35 and hydraulic pump hose 36 (shown in Fig. 1). Fluid pressure applied by the pump will pass down the fluid passageway I08 and out the aperture I09 in the spacer sleeve I05.

The testing mandrel H0, shown in Fig. 9, makes use of a short nipple or elbow III attached to the inside of the sleeve H3. To one end of the elbow III is attached the hydraulic pump hose 36 while the other end of the elbow communicates with an aperture H2 in the sleeve I I 3. Another testing mandrel I20 is shown in Fig. 10. In this embodiment of the present invention the hydraulic pump hose may be attached to a small pipe or tube passing through the upper packing element I2I, its glands I22 and I23, and the companion flange I25.

I claim as my invention:

1. Apparatus for testing for leakage of a well installation of the type having a-fianged tubular string extending into the well and a flanged tubular well head fitting connected to said string at the surface by means comprising a seal ring between the flanged portions of said tubular string and well fitting, said seal ring having a diameter greater than the inside diameter of said tubular string, said apparatus comprising a test mandrel insertable into said tubular well head fitting and depending into said tubular string, an upper packer carried by said mandrel adapted to seal ofl said tubular well head fitting above said seal ring, a lower packer carried by said mandrel adapted to seal off said tubular string below said seal ring, fluid passage means extending through said well head fitting for applying fluid pressure to the space defined by said two packers within said tubular well head fitting and string, whereby said pressure is applied to the connection formed by said seal ring, and indicating means for registering a decrease of said pressure due to leakage from said space.

2. Apparatus for testing for leakage of a well installation of the type having a flanged tubular string extending into the well and a flanged tubular well head fitting attached to said string at the surface by a connection element between the flanged portions of said tubular string and well fitting, said apparatus comprising a test mandrel insertable into said tubular well head fitting and depending into said tubular string, an upper packer carried by said mandrel adapted to seal off said tubular well head fitting above said connection element, a lower packer carried by said mandrel adapted to seal ofi said tubular string below said connection element, fluid passage means extending through said well head fitting for applying fluid pressure to the space defined by said two packers within said tubular well head fitting and string, whereby said pressure is applied to said connection element, and indicating means for registering a decrease of said pressure due to leakage from said space.

CHARLES HANSEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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