US3247903A - System and method for running and hanging tubing in a well - Google Patents

Description

April 26, 1966 w. P. KNIGHT SYSTEM AND METHOD FOR RUNNING AND HANGING TUBING IN A WELL Filed April 2. 1965 2 Sheets-Sheet 1 r 1 aww aawvax lgjlll INVENTOR A'ITORNEY A ril 26, 1966 w. P. KNIGHT 3,247,903

SYSTEM AND METHOD FOR RUNNING AND HANGING TUBING IN A WELL 2 Sheets-Sheet 2 Filed April 2, 1965 R o T N E v m ATTORNEY United States Patent 3,247,903 EiYSTEh/l AND METHUD FOR RUNNING AND HANGING TUBING TN A WELL Warner P. Knight, Rte. 9, Box 236, Fort Worth, Tex. Filed Apr. 2, 1965, Ser. No. 463,413 3 Claims. (tCl. 166-47) This application is a continuation-in-part of copending application, Serial No. 86,892, filed February 3, 1961, now abandoned.

This invention relates to a method and system for running tubing into a well and for suspending this tubing under tension in a sealed relationship in a tubing head so as to permit raising or lowering of the tubing relative to the tubing head while maintaining a well under control.

In a more specific aspect, the invention is particularly useful for installing a plurality of strings of tubing in a given well. Dual completions and other multiple completions involving more than two strings of tubing in a well have been found highlydesirable in order to provide separate communication to each of a plurality of different producing zones. Multiple strings of tubing are installed in a well with packers sealing the annulus between the tubing strings and the casing in the well in order to maintain separately the production from each of the producing zones.

By way of example, where two strings of tubing are employed for producing two vertically spaced zones, general practice is to set a first packer above the lower of the zones and then to run a second packer into the well on the first string of tubing. Thereafter a second string of tubing is run into the well and connected into the second packer. Production through the first string of tubing is from a zone below the first packer, and production through the second string of tubing is from a zone between the first or lower packer and the second or upper packer.

In such installations, it has been found desirable to maintain all tubing strings in tension, that is, stretched in a manner similar to an elastic band. Difiiculty has been encountered with existing equipment in setting dual or multiple tubing strings in tension not only because they may not be manipulated while the well is under pressure, but because in the initial installation it is often found necessary to cut and thread the upper end of tubing at the tubing head so that tubing hangers may be suited with the proper tension on the tubing. Particular difficulty is encountered installing tubing in wells which are under pressure.

It is an object of the present invention to provide a system and method for hanging tubing in a well which permits operation with the well under positive control at all times during the installation, and which permits ready adjustment of well head equipment after initial installation while maintaining the well under control.

More particularly in accordance with the present invention, well head equipment is provided for a tubing installation which includes a tubing head having an opening extending therethrough with an intermediate element adapted to be supported and sealed in the tubing head and having a plurality of openings therethrough. A tubing hanger in each opening is cooperable with the intermediate element and to be supported by the intermediate element. At least one nipple connected to the bottom of each tubing hanger supports a section of tubing extending into the well. Provision is made for maintaining a pressure seal between the nipple exterior and the interior of the intermediate element below each tubing hanger.

In a more specific aspect, the invention relates to a system for installing and maintaining a string of tubing in a well under tension while maintaining the well under 3,2473% Patented Apr. 26, 1 .966

control, and includes a tubing head having a reentrant bore therethrough with a first upfacing shoulder'therein. A sealing bowl seats on said upfacing shoulder. Means carried by the sealing bowl engages the wall of the reentrant bore to maintain a pressure tight seal therebetween. The sealing bowl has at least one reentrant aperture extending therethrough with an intermediate upfacing shoulder. A tubing hanger in the sealing bow-1 aperture is seated on the intermediate upfacing shoulder. At least one nipple is provided to interconnect the bottom of the hanger and tubing extending into the well with the nipple extending through the sealing bowl. Sealing means carried by the nipple is adapted to engage the walls of the aperture to maintain a pressure-tight seal therebetween and to permit movement through the sealing bowl of the nipple for manipulation of the tubing string while maintaining well control.

For a more complete understanding of the present invention and for further objects and advantages thereof, reference may now be had to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross sectional elevational view of a tubing installation in accordance with the present invention;

FIG. 2 is a fragmentary cross sectional elevational view showing a special sealing nipple being run into a well through a sealing bowl;

FIG. 3 is a fragmentary top plan view taken along the lines IIIIII of FIG. 2;

FIG. 4 is a cross sectional view taken along the line IVIV of FIG. 1;

FIG. 5 is a fragmentary cross sectional view taken along the line VV of FIG. 1;

FIG. 6 is a perspective exploded view of one of the tubing hangers and one of the sealing nipples provided in accordance with the present invention; and

FIG. 7 is a schematic elevational view of a back pressure valve which may be used in connection with the invention.

Referring now to FIG. 1, a pair of nipples 10 and 11, each having a substantially cylindrical exterior surface and a longitudinal bore, are connected at the lower ends thereof to like nipples 1.2. and 13 which in turn are connected to additional similar nipples (not shown) at the lower ends thereof and thence to support a pair of strings of tubing (not shown). The bores extending through the respective sets of nipples provide for separate flow of production from two zones penetrated by the well in which said tubing is installed.

The nipples Ill and H are supported at the upper ends thereof by tubing hangers 14 and 15, respectively. The manner in which the nipples 10-13 function with associated elements to permit raising and lowering of tubing hangers M and 15 to install tubing under tension is a significant contribution to the petroleum producing art.

As illustrated in FIGv 1, a tubing head 20 is affixed to the casing head 21 by bolts coupling the upper radial flange on the casing head 21 and the lower radial flange on the tubing head 20. Tubing head 20 is provided with an upper radial flange 2,2 to which there is connected, upon the completion of the installation, a flanged coupling element 23 which accommodates connections to production control equipment commonly known as a Christmas tree.

The tubing head 20 is provided with a pair of lateral ports 24 and 25 which communicate with the annular zone in the well. The upper section of the tubing head 2% is provided with an enlarged bore 26 of substantially greater diameter than the bore 27 of the lower intermediate portion of the tubing head. The bores 26 and 27 may thus be understood to form a reentrant opening extending through the tubing head with an upfacing sloping shoulder 28. The tubing head is provided with a plurality of bushings, such as bushing 30, through which set screws 31 extend. Screws 31 may extend into the cavity within the tubing head 20.

An intermediate element hereinafter referred to as a sealing bowl 32 is adapted to be inserted into bore 26 in the upper portion of the tubing head 26. The diameter of the sealing bowl 32 is slightly less than the diameter of the bore 26 so that it may readily be inserted. The O-rings 33 mounted in grooves in the exterior surface of the sealing bowl 32 near the upper end and the O-rings 34 mounted in grooves on the exterior surface of the sealing bowl 32 near the lower end thereof engage the inner wall of the bore 26 to maintain a pressure-tight seal therein. When the sealing bowl 32 is inserted into the bore 26 to rest upon shoulder 28, the hold down screws 31 are tightened to engage the exterior surface of the sealing bowl 32 preferably on milled flat areas provided at circumferentially spaced points.

The sealing bowl 32 is provided with a pair of reentrant bores. The right hand bore has a lower section 40 constituting a cylindrical inner surface of diameter smaller than the diameter of the upper section 41. Similarly, the left hand bore has a lower section 42 constituting a cylindrical inner surface of diameter smaller than the diameter of the upper section 43. Lower sections 40 and 42 are both of sufiicient diameter to permit tubing strings to be fed therethrough (including the tubing collars). An upfacing shoulder such as shoulder 44 having a sloping face is provided between lower bore 40 and upper bore 41. In a similar manner, a shoulder 45 having a sloping face is provided between the lower bore 42 and the upper bore 43 in the left hand channel.

Tubing hanger 14 connected to the upper end of nipple is provided with a shoulder which seats on the shoulder 44 in order to provide a positive support for the nipples and tubing extending therebelow. Tubing hanger similarly seats on the shoulder 45.

The upper end of the sealing bowl 32 is provided with at least one radial port for each bore therethrough in order to permit hold down screws such as screws 50 and 51 to extend through the walls of the sealing bowl 32 near the upper end into engagement with the exterior surface of tubing hangers 14 and 15, respectively. Hangers 14 and 15 are provided with circumferential grooves into which-the hold down screws 50 and 51 extend.

As above stated, the cylindrical inner surfaces or bores 40 and 42 are of suflicient size to permit the free movement of the tubing and tubing collars therethrough and are larger than the diameter of the nipples 10-13. However, each of the nipples is provided with a plurality of O-rings, the latter being spaced along the length of each such nipple and so dimensioned as to provide a pressuretight seal between the nipple and the cylindrical inner surfaces 40 and 42.

More particularly, a pair of O-rings 60 carried in grooves around the upper end of the nipple 10 contact the inner wall of the bore 4%). Immediately below the O-rings 60 there is provided a milled zone 61, preferably providing four flat surfaces in the periphery of the nipple 10. Below the zone 61 there are provided additional O-rings such as rings 62, 63 and 64. O-rings or packing elements are sized for sealing engagement with the respective cylindrical inner surfaces 40 and 42 and 62-64 are provided in number sufiicient to permit the tubing hanger 14 and nipples 10 and 12 to be raised in the well while maintaining at all times a positive pressure seal between at least one nipple below a tubing hanger 14- and the wall of the bore 40 through which the nipples pass.

For example, as shown in the fragmentary sectional view of FIG. 2, tubing hanger 15 of FIG. 1 has been raised relative to the upper flange 22 of the tubing head and removed. The nipple 11 is shown extending slightly above the surface of flange 2-2 and supported by a special wrench-like tool sometimes herein called a hanging tool which rests upon the upper surface of the flange 22 and which engages the flats in the zone 61 of FIG. 1. In this case, a seal between the nipple 11 and the bore 42 is maintained by the O-rings carried by the lower portion of the nipple 11. With the nipple 11 in the position shown in FIG. 2, additional nipples may be secured thereto to permit the tubing string to be lowered to even greater depths. Alternatively, the nipple may be further elevated in the well to apply further tension on the tubing.

The use of the hanging tool 70 for supporting the nipple 11 is best shown in FIG. 3. The tool has a rectangular opening 71 which in dimensions corresponds with the cross section of the nipple 11 at the milled zone 61. It is understood that the hanging tool 70 could take any convenient form that would be compatible with its function, and also, the milled zone 61 could take any convenient form that would provide a suitable means on the outer periphery of each nipple intermediate the ends thereof to accommodate the hanging tool.

FIG. 4 illustrates a sectional view taken along the line IVIV of FIG. 1 more clearly to show the cross sectional configuration of the nipples 10 and 11 together with the flat zones on the surface of the sealing bowl 32 provided to receive the hold down screws 31. It will be seen that the annulus 32a between the sealing bowl 32 and bore 26 is sealed by the O-ring 34 while the annulus between the nipple 10 and the bore 40 is sealed by the O-ring 62. In a similar manner the annulus between the nipple 11 and the bore 42 is sealed by O-ring 62a.

FIG. 5 illustrates structure for positioning the sealing bowl 32 in the bore 26. In this regard reference should first be had to orienting depressions 28a and 28b shown in FIG. 1, milled in diametrically opposed portions of the shoulder 28a. The depressions 28a and 28b are adapted to mate with projections formed on the lower end of the sealing bowl 32. More particularly, the sealing bowl 32 has two diametrically opposed projections extending below the surface of the beveled shoulder 28. In FIG. 5, one projection 32b is illustrated positioned in depression 28b. When the sealing bowl is inserted into the bore 26, it is rotated until the projections, such as projection 32b, register with the depressions, such as the depression 28b.

When this is accomplished, the hold down screws 31 are in alignment with the flat zones on the exterior surface of the sealing bowl 32 and at the same time the hold down screws 51 are in alignment with the radially extending holes in the upper end of the sealing bowl 32.

FIG. 6 illustrates an exploded view showing the tubing hanger 14 and the upper nipple 10. The tubing hanger 14 has the radial groove 14a into which the hold down screw 51 of FIG. 1 extends. The upper end of the tubing hanger 14 is provided with a pair of sealing rings 14b which serve to maintain a seal between the tubing-hanger and the Christmas tree structure 23 (FIG. 1).

In operation, a dual completion'rnay be carried out as follows:

(a) Upon completion of drilling operation and the setting and cementing of casing, the well is drilled in and a blow-out preventer is installed on the upper flange 22 of the tubing head 20. The tubing head 20 is then fastened to the casing head 21.

(b) The well casing is then perforated at two zones of interest and a first packer set at a selected depth between the perforated zones.

(c) A first string of tubing is introduced into the well through the blow-out preventer.

(d) A second packer is mounted on the first string of tubing and lowered below the tubing head.

(e) The sealing bowl 32 is installed in the tubing head through the blow-out preventer, over the first string of tubing, and the hold down screws 31 are tightened to maintain the tubing bowl in a fixed position in the tubing head 20 with the projections, such as projection 32b, in the depressions, such as 28b, FIG. 5.

(f) The first tubing string is then lowered to locate the second or upper packer above the upper set of perforations and to couple the lower end of the tubing into the first or lower packer.

(g) Nipples, such as nipples l0 and 12, are connected to the upper end of the first string of tubing along with a tubing hanger 14. The latter is then lowered into the sealing bowl 32.

(h) The second string of tubing is then lowered through the bore 42 by way of the blow-out preventer until the bottom end of the second string of tubing touches the upper packer. The second string is then raised and nipples 11 and 13 are installed in the second string thereof along with an intermediate length of tubing, if necessary. The tubing hanger 15 is added and is seated in the bore 43 with the lower end adjacent to the upper packer.

(i) Tubing hangers 14 and 15 are locked in place by the hold down screws Sit and 51.

(1') At this point the blow-out preventer may be removed since the sealing bowl is locked in position by hold down screws 31, the tubing hangers 14 and 15 are locked in position by hold down screws 50 and 51, and the head of the well is sealed by O- rings 33 and 34 between the sealing bowl 32 and the tubing head 20 and by O-rings on each of the nipples.

When necessary, back pressure valves such as shown in FIG. 7 may be installed in one of the nipples -13 or may be installed in the tubing strings near the lower ends thereof to close the tubing channels.

(k) The tubing hangers 14 and are raised and while in raised position such as illustrated in FIG. 2 are removed so that additional nipples may be added to each of the strings of tubing to permit the lowering of the first string suflicient to lock said first string in the lower packer and to permit the first string t be raised to set the upper packer and to place the first string in tension. The desired tension may stretch the tubing in some cases as much as 50 inches so that nipples sufiicient in number to accommodate the setting of the upper packer and tensioning the first tubing string will be necessary. Similarly, nipples sufficient in number are installed on the second string to permit it to be stabbed into and secured to the upper packer for production from the zone between the lower and upper packers. The second string of tub-ing must also be tensioned, nipples in number sufficient to permit the tensioning operation being included.

(l) The tubing strings are raised successively by applying tension thereto to pull one or several of the nipples 1013 on each string above the tubing head flange 22.

(m) When sufficient tension has been registered on a first of the string oftubing, hanging tool 70 is fixed to the flat surfaces on the nipple positioned immediately above the top of the flange 22.

(n) The first string of tubing is lowered so that the wrench or hanging tools 70 take the weight of the string and the tensile force therein while the nipples above the flange 22 are removed and replaced by a tubing hanger.

(o) The string of tubing are raised slightly to permit removal of the hanging tools 70 and the tubing hanger is lowered into the sealing bowl.

(p) Steps (In) and (o) are repeated for the second string.

(q) The Christmas tree structure 23 is added for producing through the strings of tubing, and the back pressure valves are removed from the tubing or nipples.

It will be understood that the foregoing operations permit the reworking of the tubing strings while maintaining the Well under control. Greater or less tension can be set into the tubing strings by merely raising the tubing hanger out of the sealing bowl and adding or removing nipples as desired. In each case, however, the nipples employed maintain a pressure-tight seal between the ex 6 terior of the nipples and the interior of the sealing bowl 322.

It will be clear from the foregoing that the minimum effective increment that the tubing string may be lengthened or shortened is the length of one nipple. This is also the distance between the hanging tool accommodating means on adjacent nipples. Further, the minimum effective length for a nipple is the length of the intermediate element cylindrical inner surface. There must always be at least one nipple below each tubing hanger. The minimum spacing between adjacent packing elements, whether on one nipple or on adjacent nipples, must not exceed the length of an intermediate element cylindrical inner surface.

The term packing element as used herein is intended to encompass a sealing element such as an O-ring as well as any suitable sealing element means well known to those skilled in the art that will accomplish the requisite pressure seal. The packing elements could also make up a solid longitudinally extending seal on each nipple of length exceeding that of the intermediate element inner cylindrical surface, if that were desired.

While the foregoing has dealt specifically with a dual completion system, it is to be understood that features of the invention may be employed for hanging as many strings of tubing as can be accommodated by the casing in a tubing head in the manner above described by use of a sealing bowl with additional channels extending therethrough.

Components discussed and not illustrated, but used as adjuncts to hanging plural strings of tubing in carrying out the present method are well known in the art. The blow-out preventer, packers, back pressure valves, and other conventional apparatus used in connection with the invention may all be of any suitable make or type as will be readily understood by those familiar with the petroleum production art.

Applicant has, however, devised a new system and a new method for the handling and manipulation of multiple completion well head equipment. with a reentrant bore therethrough is of size suflicient to admit as many strings of tubing as desired. The intermediate sealing bowl element is adapted to be supported and sealed in the tubing head and is provided with as many openings therethrough as tubing strings to be placed in the well. A tubing hanger is provided in each such opening in the sealing bowl and cooperates with means in the sealing bowl for supporting the hanger. At least one nipple is connected to the bottom of each tubing hanger and is adapted to support a section of tubing in each string in the well. Pressure seal means are provided to seal the annulus between the sealing bowl and the tubing head and between the nipples and the channels through the sealing bowl.

It will be seen that the invention relates not only to construction of the well head equipment, but also to a new method of hanging tubing in a well involving operations extending into the hole itself and particularly the cooperation between the well head equipment and the packers in the well.

In carrying out the method of the present invention to set a pair of tubing strings through the bore of a Well head below which a first packer is installed, the steps set forth above will be followed. One of the tubing strings carrying a second packer is inserted through the bore of the tubing head. The bore of the tubing head is then stopped except for two passages therethrough, the first of which is an annular passage concentric with the first string of tubing and the second of which is a cylindrical passage parallel to the first annular passage for introduction of a second string of tubing.

The first string of tubing is then lowered until the sec-' ond packer is at a predetermined depth. The second string of tubing is then introduced through the cylindrical passage until the lower end thereof is adjacent the top of The tubing head the second packer. There are then established slidable annular seals in the first annular passage, and also in a second annular passage between the second string of tubing and the cylindrical passage through which it extends. The strings of tubing, the second packer and the first packer are then interconnected below the well head and coupled to the wall of the well while maintaining the annular seals in the tubing head. Tension is then applied to stretch the strings of tubing while maintaining the annular seals. The tubing strings are then hung in the well head while maintaining tension on the strings of tubing through the annular seals. Thus at all times the well pressure is sealed by the O-rings or packing elements carried by the sealing bowl and by the nipple-formed tubing sections.

Having described the invention in connection with certain embodiments thereof, it is to be understood that further modifications may now suggest themselves to those skilled in the art, and it is intended to cover such modifications as fall within the scope of the appended claims.

I claim:

1. In setting of a pair of tubing strings through a blow-out preventer and the bore of a tubing head below which a first packer is installed, while maintaining said Well under control; the method which comprises:

(a) introducing as a unit one of said strings of tubing and a second packer through said blow-out preventer and said bore;

(b) stopping said bore except for two passages therethrough the first of which is an annular passage concentric with said first string of tubing and the second of which is a cylindrical passage parallel to said first annual passage for introducing a second string of tubing;

() lowering said first string of tubing until said second packer is at a predetermined depth;

(d) introducing a second tubing string through said blow-out preventer and said cylindrical passage until the lower end thereof is adjacent the top of said second packer;

(e) establishing slidable annular seals in said first passage and in said second annular passage between said second string of tubing and said cylindrical passage;

(f) removing said blow-out preventer;

(g) interconnecting both strings of tubing, said first packer and said second packer while maintaining said annular seals in said well head;

(h) applying tension to stretch said strings of tubing while maintaining annular seals in said well head;

(i) and hanging each said string of tubing in said well head while maintaining annular seals in said well head.

2. In setting of a pair of tubing strings through the bore of a tubing head below which a first packer is installed and through which one of said strings of tubing and a second packer have been inserted; the method which comprises:

(a) stopping said bore except for two passages therethrough, the first of which is an annular passage concentric with said first string of tubing and the second of which is a cylindrical passage parallel to said first annular passage for introducing a second string of tubing;

(b) lowering said first string of tubing until said second packer is at a predetermined depth;

(0) introducing a second string of tubing through said cylindrical passage until the lower end thereof is adjacent the top of said second packer;

(d) establishing slidable annular seals in said first annular passage and in a second annular passage between said second string of tubing and said cylindrical passage;

(e) interconnecting both strings of tubing, said first packer and said second packer below said well head while maintaining said annular seals in said well head;

(f) applying tension to stretch said strings of tubing while maintaining said annular seals in said well head;

(g) and hanging each said string of tubing in said well head while maintaining annular seals in said well head.

3. In the installation of a pair of tubing strings through the bore of a tubing head mounted on a well casing string and below which a first packer is installed; the method which comprises:

(a) introducing as a unit one of said strings of tubing and a second packer through said bore;

(b) stopping said bore except for three passages each more restricted than said bore, the first of which is an annular passage concentric with said bore, the second of which is an annular passage concentric with said first string of tubing and the third of which is a cylindrical passage parallel to said first annular passage for introducing a second string of tubing;

(c) lowering said first string of tubing until said second packer is at a predetermined level;

(d) introducing said second tubing string through said cylindrical passage until the lower end thereof is adjacent the top of said second packer;

(e) establishing slidable annular seals in said first annular passage, in said second annular passage and in a third annular passage between said second tubing string and said cylindrical passage;

(f) interconnecting below said Well head said strings of tubing, said first packer and said second packer and said casing while maintaining said annular seals in said well head;

(g) applying tension to stretch both said strings of tubing from said upper packer while maintaining said annular seals in said well head;

(h) and hanging each said string of tubing in said well head while maintaining annular seals in said well head.

References Cited by the Examiner UNITED STATES PATENTS 2,103,586 12/1937 Kitchel et al 285143 2,889,886 6/1959 Gould 16689 2,905,099 9/1959 Turner 16689 X 3,041,090 6/1962 Ashe et a1 285-437 3,080,180 3/1963 Rector 285-137 CHARLES E. OCONNELL, Primary Examiner.

J. A. LEPPINK, Assistant Examiner.

Claims (1)

1. IN SETTING OF A PAIR OF TUBING STRINGS THROUGH A BLOW-OUT PREVENTER AND THE BORE OF A TUBING HEAD BELOW WHICH A FIRST PACKER IS INSTALLED, WHILE MAINTAINING SAID WELL UNDER CONTROL; THE METHOD WHICH COMPRISES: (A) INTRODUCING AS A UNIT ONE OF SAID STRINGS OF TUBING AND A SECOND PACKER THROUGH SAID BLOW-OUT PREVENTER AND SAID BORE; (B) STOPPING SAID BORE EXCEPT FOR TWO PASSAGES THERETHROUGH THE FIRST OF WHICH IS AN ANNULAR PASSAGE CONCENTRIC WITH SAID FIRST STRING OF TUBING AND THE SECOND OF WHICH IS A CYLINDRICAL PASSAGE PARALLEL TO SAID FIRST ANNUAL PASSAGE FOR INTRODUCING A SECOND STRING OF TUBING; (C) LOWERING SAID FIRST STRING OF TUBING UNITL SAID SECOND PACKER IS AT A PREDETERMINED DEPTH; (D) INTRODUCING A SECOND TUBING STRING THROUGH SAID BLOW-OUT PREVENTER AND SAID CYLINDRICAL PASSAGE UNTIL THE LOWER END THEREOF IS ADJACENT THE TOP OF SAID SECOND PACKER; (E) ESTABLISHING SLIDABLE ANNULAR SEALS IN SAID FIRST PASSAGE AND IN SAID SECOND ANNULAR PASSAGE BETWEEN SAID SECOND STRING OF TUBING AND SAID CYLINDRICAL PASSAGE; (F) REMOVING SAID BLOW-OUT PREVENTER; (G) INTERCONNECTING BOTH STRINGS OF TUBING, SAID FIRST PACKER AND SAID SECOND PACKER WHILE MAINTAINING SAID ANNULAR SEALS IN SAID WELL HEAD; (H) APPLYING TENSION TO STRETCH SAID STRINGS OF TUBING WHILE MAINTAINING ANNULAR SEALS IN SAID WELL HEAD; (I) AND HANGING EACH SAID STRING OF TUBING IN SAID WELL HEAD WHILE MAINTAINING ANNULAR SEALS IN SAID WELL HEAD.

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