US3897824A

US3897824A - Blowout preventer testing apparatus

Info

Publication number: US3897824A
Application number: US503308A
Authority: US
Inventors: Edmund A Fisher
Original assignee: Cameron Iron Works Inc
Current assignee: Cooper Industries LLC
Priority date: 1974-09-05
Filing date: 1974-09-05
Publication date: 1975-08-05
Anticipated expiration: 1992-08-05

Abstract

Apparatus is disclosed for pressure testing a blowout preventer wherein a body is suspended from a pipe string for lowering into a testing position in which it seals with respect to the bore of a wellhead beneath the preventer, so that upon closure of the rams of the preventer about the pipe string, a space is enclosed to receive test pressure. The body has openings through it to permit well fluid to by-pass the seal as the body is raised and lowered, and valve means are provided for closing the openings when the body is in testing position.

Description

United States Patent [191 Fisher 1 1 BLOWOUT PREVENTER TESTING APPARATUS [75] Inventor: Edmund A. Fisher, Houston, Tex.

[73] Assignee: Cameron Iron Works, Inc.,

Houston, Tex.

22 Filed: Sept. 5, 1974 211 Appl. No.1 503,308

1 1 Aug. 5, 1975 Balmer et a1v 166/87 Nelson et a1 166/85 Primary E.ran1inerDavid H. Brown Attorney Agent, or Firm-W. F. Hyer; Marvin B. Eickenroht [5 7] ABSTRACT Apparatus is disclosed for pressure testing a blowout preventer wherein a body is suspended from a pipe string for lowering into a testing position in which it seals with respect to the bore of a wellhead beneath the preventer, so that upon closure of the rams of the preventer about the pipe string, a space is enclosed to receive test pressure. The body has openings through it to permit well fluid to by-pass the sea] as the body is raised and lowered. and valve means are provided for closing the openings when the body is in testing position.

5 Claims. 6 Drawing Figures PATENTEDMIG 51975 3.897, 824

sum

BLOWOUT PREVENTER TESTING APPARATUS This invention relates to apparatus for pressure testing blowout preventers; and, more particularly, to improvements in apparatus of the type comprising a body which is lowerable on a pipe string into the bore of a wellhead connected beneath the preventer so as to seal thereagainst, when so lowered. whereby closure means on the preventer may be extended into sealing engagement about the pipe string to enclose an annular space thereabout into which fluid under pressure may be introduced in order to test various parts of the preventer.

In one prior apparatus of this type, a cup type packer is carried about the body for direct sealing engagement with the bore of the wellhead. However, when the preventer is installed on an underwater wellhead, the close fit of the packer within the riser pipe above the pre venter stack, which is necessary in order to permit the packer to seal against the wellhead bore, makes it necessary to raise and lower the apparatus at a very slow rate.

In another prior apparatus of this type, such as that shown in US. Pat. No. 3,177,703, an annular seal assembly is carried by the body for lowering into an annular space between the bore of the wellhead and a casing hanger supported therein in order to seal with respect to both the bore and the outside of the hanger. A cup type packer is also carried by the body for sealing against the inside of the casing hanger, whereby the body is effectively sealed with respect to the wellhead bore and both the seal assembly and preventer may be pressure tested. Although well fluid may be permitted to by-pass the seal assembly, and thereby enable the body to be raised and lowered more rapidly, it has been found that if the seal between the outer side of the seal assembly and the wellhead bore fails to hold test fluid pressure, such pressure, upon leaking into the annulus between the wellhead bore and the casing string suspended from the hanger, can cause the casing string to collapse.

An object of this invention is to provide apparatus which may be raised and lowered at a relatively fast rate, and which can be used to test the preventer without danger of collapsing a casing string suspended from a casing hanger within the wellhead bore.

Another object is to provide such apparatus which may be used in a manner to permit pressure testing of the preventer merely upon manipulation of the pipe string from which the body is suspended, and preferably merely in response to vertical reciprocation of the pipe string.

These and other objects are accomplished, in accordance with the illustrated embodiment of the invention, by apparatus of the type described in which at least one opening is formed through the body to permit well fluid to by-pass the sealing means, and valve means is mounted on the body for movement between a position opening the bypass to permit the body to be raised and lowered at a fast rate, and a position closing the by-pass so as to enclose a test space above the body when the body is supported in testing position and the preventer rams are closed about the pipe string. Means are provided for holding the valve means in open position, as the body is lowered into supported position, and for moving it from open to closed position, when the body is so supported, and then for moving it from closed to open position, following the test, to permit the body to be lifted from supported position within the well bore.

More particularly, the body has a bore therethrough which is open to upward flow in order to relieve fluid test pressure which is not held by the sealing means, whereby such pressure is not imposed on the outside of the casing suspended from the casing hanger.

In the preferred and illustrated embodiment of the invention, the body is suspended from the pipe string by means of a tubular member which extends through the body to define the bore therethrough, and which carries the valve means for movement with respect to the body, and thus the by-pass openings, between its opened and closed positions. The valve means is held in open position by at least one shear pin releasably connecting the tubular member to the body, and the tubular member is vertically reciprocable with respect to the body to permit the pin to be sheared, whereby the by-pass openings may be opened and closed merely by control of the weight of the pipe string. Preferably, there are a plurality of by-pass openings, and the valve means comprises a plate for opening and closing all of the by-pass openings.

In the preferred and illustrated embodiment of the invention, the body comprises an outer sleeve which has means on it for landing in the wellhead bore, and a central portion adapted to be suspended from the pipe string and releasably connected to the sleeve for vertical reciprocation therein. The central body portion has a downwardly facing shoulder thereabout, the sleeve having an upwardly facing shoulder thereabout beneath the shoulder on the central portion, and a sealing means comprising a seal ring surrounds the central body portion intermediate the shoulders and is arranged to be moved into sealing engagement with the wellhead bore upon manipulation of the string to release the connection between the central portion and the sleeve, following landing of the sleeve in the wellhead bore, and lowering of the central body with respect to said sleeve. The connection between the central body portion and sleeve comprises a shear pin which is releasable in response to increase weight of the pipe string.

In the drawings:

FIG. 1 is a vertical sectional view of apparatus con structed in accordance with the present invention and disposed within the bore of a wellhead, the view being vertically interrupted to illustrate, in its upper portion, a blowout preventer connected above the wellhead, and, in its lower portion, the body of the apparatus landed upon a seal assembly within a lower portion of the wellhead bore, such lower portion being viewed along broken lines 1-1 of FIG. 6;

FIG. 2 is a partial vertical sectional view of the apparatus showing the central portion of the body lowered with respect to the outer sleeve thereof to move the seal ring about the body into sealing engagement with the wellhead bore;

FIG. 3 is another partial vertical sectional view of the apparatus, vertically interrupted similarly to FIG. I, showing the tubular member lowered to a position closing the by-pass openings through the body, and the rams of the blowout preventer extended inwardly to close about the pipe string above the body;

FIG. 4 is another partial vertical sectional view of the apparatus, showing the tubular member raised to lift the body from landed position upon the seal assembly and cause the seal ring to be moved out of sealing engagement with the wellhead bore;

FlG. 5 is a cross-sectional view of the apparatus. as seen along broken lines 5-5 of FIG. I; and

FIG. 6 is another cross-sectional view of the apparatus. as seen along broken lines 6-6 of H6. 1.

With reference now to the details of the abovedescribed drawings. the overall apparatus. which is indicated in its entirety by reference character 20, is shown in FIG. I to he landed within a bore 21 of an underwater wellhead member 22 connected beneath a blowout preventer 23 to be tested. As also shown. the apparatus is suspended from a string of pipe P to permit it to be raised and lowered within bore 21 as well as a bore 24 through a housing 25 of the preventer, which forms an upward continuation of the wellhead bore. and a bore through a riser pipe (not shown) which extends above the preventer housing to water level. Ordinarily. the bore of the riser pipe is not substantially greater than that of the wellhead and blowout preventer, and may be several hundred feet or more in length.

As shown in FIGS. 1 and 3, the lower end of preventer housing 25 has a flange connected to a flange on the upper end of the wellhead member 22 and sealed with respect thereto by means of a seal ring 26 held within matching grooves in the flanges. The upper end of the preventer housing (not shown) may be connected and sealed with respect to the lower end of the riser pipe in a similar manner. Also, it will be understood that there may and usually will be more than one preventer connected above the wellhead member, thereby forming a stack. The apparatus of the present invention is useful in pressure testing one or more of these preventers, and the description of only one will illustrate its utility.

Guideways 27 radiate outwardly from the preventer bore 24 to receive pipe rams 28 which are slidable therein between positions withdrawn from the bore. as shown in FIGv l, and within the bore for sealing about pipe string P, as shown in FIG. 3. The outer ends of the guideways are closed by bonnets (not shown), and as also shown in FIGS. 1 and 3, a choke or kill line 29 extends downwardly from the water level to connect at its lower end with the preventer bore 24 beneath the rams.

As previously described. when apparatus is lowcred to the position of FIG. 1, a seal ring R carried thereby is caused to seal against the wellhead bore 21 beneath the preventer, as shown in FIG. 3. Then, rams 28 may be moved inwardly to seal about the pipe P to enclose an annular space S into which test fluid under pressure may be introduced through line 29 for testing the various parts of the preventer, including the sealing engagement of its rams with the pipe string, the connection of bonnets across the outer ends of the ram guideways in the housing. and the sealed connection of the preventer to the wellhead member.

As also known in the art, and as shown in the aforementioned U.S. Pat. No. 3,l77,703, one or more casing hangers (not shown) may be landed within the wellhead bore for suspending casing strings therein. More particularly, these casing hangers are of the type which define openings through an annular space between each hanger and the wellhead bore to permit cement returns to pass upwardly therethrough as a casing suspended from the hanger is cemented in the well bore. Following circulation of cement returns through the openings, they are closed by means of a seal assembly A lowered into the annular space and having a seal AR about its outer side for sealing it with respect to the wellhead bore. Another portion (not shown) of the seal assembly is adapted to seal with respect to the casing hanger, so that, as will be understood, and as previously mentioned. leakage of pressure fluid downwardly past seal AR could cause the casing suspended from the easing hanger to be collapsed.

The apparatus 20 comprises an annular body 30 having a downwardly facing shoulder 34 thereabout for landing upon the upper end of seal assembly A and a central passageway 3| therethrough, and a tubular member 32 which is vertically reciprocable within the passageway. The upper end of the tubular member has threads 33 connecting it to the lower end of the pipe string P, so that its bore provides a bore through body 30 which forms a continuation of the lower end of pipe string P. The tubular member 32 includes an upper tube 39 on which the threads 33 are formed, and a sub 40 connected to the lower end of the tube 39. The upper end of the sub 40 provides a shoulder 42 which is received within a counterbore 41 in the lower end of the body bore 31, when the tubular member is in raised position, as shown in FIG. 4, to support a downwardly facing shoulder 43 on the upper end of the counterbore 41.

A plurality of the by-pass openings 35 are provided through the body to connect its upper end with its lower end and thereby by-pass the seal ring R carried about the body. A valve plate 36 is carried by the tubular member for movement therewith between a raised position above the openings 35 to permit well fluid to by-pass through the openings, and a lower position over the upper ends of the openings to close them. in its lower, closed position, the valve plate 36 fits within a recess 37 in the top of the body and connecting with the upper ends of the openings 35. The plate 36 carries a cup type seal ring 38 for sealing with respect to the outer wall of the recess 37, when the plate is so lowered, in order to close the lower end of space S.

When the apparatus has been lowered to land shoulder 34 on the upper end of seal assembly A, downward movement of tubular member 32 is limited by means of a shear pin 44 connecting it to a ring 45 seatable within a counterbore 46 in the upper end of bore 31, so as to hold valve plate 36 in the open position shown in FIG. 1. Pin 44 is sheared when the required weight is placed on pipe string P, whereby the tubular member may be lowered within body 30 to move plate 36 downwardly into seated position within recess 37.

Body 30 of the apparatus includes a central portion 47 having passageway 31 formed therein, an outer diameter about which seal ring R is disposed, and by-pass openings 35 extending therethrough. The body also includes a sleeve 48 which has a shoulder 34 formed on its lower end and which surrounds a reduced, lower diameter of the outer side of body portion 47. The sleeve is supported from body portion 47 by means of a nut 49 threadedly connected to the lower end of such portion. The sleeve has an upper extension 50 on its outer side which surrounds an enlarged upper diameter of the central body portion beneath seal ring R, and the upper end of body portion 47 has a further enlarged part 51 disposed above seal ring R. Central body portion 47 is releasably held by a shear pin 55 in a raised position with respect to sleeve 48, and as the apparatus is lowered into landed position, the outer diameter of seal ring R is substantially aligned with the outer diameters of sleeve 48 and the upper end 51 of body portion 47, and thus in non-sealing engagement with the wellhead bore.

Seal ring R is moved to sealing position merely in response to downward movement of body portion 47 due to increased weight on pipe string P. For this purpose. body portion 47 has upper and lower

cylindrical surfaces

52 and 53 formed thereabout beneath its enlarged upper end 51, the surface 53 being of smaller diameter than the surface 52. in its non-sealing position. the seal ring R is disposed with its inner diameter close about the cylindrical surface 53 and its outer diameter spaced from bore 21. In its sealing position, the seal ring 53 is stretched onto the surface 52, with its inner diameter tightly engaged therewith and its outer diameter in sealing engagement with the bore. 7

In its non-sealing position, the lower end of the seal ring rests upon a shoulder 54 on the upper end of sleeve 48, and its upper end is close to the lower end of a sleeve 58 releasably connected about surface 52 by means of a shear pin 59. Upon landing of sleeve 48 on the seal assembly, increased weight may be placed on the pipe string to shear

pins

55 and 59, and thus permit body portion 47 to move downwardly relative to sleeve 48. Larger cylindrical surface 52 is thus moved downwardly inside seal ring R to stretch it into sealing position, and the upper end of seal ring R pushes sleeve 58 upwardly along surface 52 until a shoulder 56 on the body portion 47 engages a shoulder 57 on the sleeve 48. Sleeve 58 is of such height that its upper end will not be forced against enlarged end 51 of the body portion 47. Thus, the only force required to so move the seal ring to sealing position is that necessary to shear

pins

55 and 59 and force surface 52 inside the seal ring, and the sealing engagement of the seal ring is pressure energized in response to pressure differentials thereacross. At the same time, the lower end of sleeve 58 is close to the upper end of stretched seal ring R to limit the extent to which it may reciprocate in response to pressure differentials.

Sleeve 58 is prevented from rotating with respect to body portion 47 by means of a pin 60 extending from it into a slot 61 in the enlarged upper end of such portion. Sleeve 48 is also prevented from rotating with respect to body portion 47 by means of a pin 62 which extends upwardly from its shoulder 57 for sliding within a hole 63 within shoulder 56 in body portion 47.

In use, apparatus is assembled with its parts in the positions shown in FIG. 1, and then connected by means of threads 33 to the lower end of pipe string P. With rams 28 of the blowout preventer retracted to their open positions, the apparatus may be lowered on the string, through the riser pipe and bore 24 in the preventer, and into bore 21 in the wellhead until shoulder 34 about sleeve 48 lands upon seal assembly A. Then, weight may be placed on the string to lower tubular member 32 so as to lower body portion 47 with respect to sleeve 48, in order to move seal ring R into sealing position, and lower member 32 with respect to body portion 47, in order to move plate 36 into recess 37 and thereby close openings 35. These functions may be caused to occur in a desired sequence, depending on the relative strength of shear pins 44, 55 and 59. As shown, pins 55 and 59 are weaker than pins 44, so that, as illustrated in FIG. 2, seal ring R has been moved to scaling position prior to closure of openings 35.

With seal ring R in sealing position, and valve plate 36 in closed position, as shown in FIG. 3, blowout preventer rams 28 may be closed about pipe string P to close space S, and fluid under pressure may be introducedinto the space through line 29 in order to test the preventer. if test pressure should leak past seal ring R, it will be relieved through the bore through tubular member 32. so that even if seal AR of seal assembly A was also defective, there would be no danger of test pressure flowing into the annulus between the casing hanger to which the seal assembly is connected and the portion of bore 21 thereabout.

Upon completion of the test. the preventer rams are retracted and string S lifted to raise tubular member 32. and thereby lift body 30 from seal assembly A and upwardly from the well. As shown in FIG. 4, lifting of body portion 47 raises it with respect to sleeve 48 to permit seal ring R to slide off of surface 52 onto surface 53 prior to raising it within the wellhead bore. As also shown in FIG. 4, as seal ring R slides back onto surface 53, sleeve 58 falls with it into a position to protect the seal ring from obstructions within the well bore.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

it will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be inter preted as illustrative and not in a limiting sense.

The invention having been described, what is claimed 1. Apparatus for use in pressure testing a blowout preventer which includes a housing having a bore therethrough sealably connected to the upper end of a wellhead, with its bore forming an upward continuation of the bore through the wellhead, and closure means mounted within the housing for extension into the bore to seal about a pipe string therein, said apparatus comprising a body, means on the body for suspending it from a pipe string, so that it may be raised and lowered therewith within the bores, and providing a bore therethrough adapted to form a continuation of the lower end of the pipe string, when the body is so suspended, said body also having means thereon for supporting it within the wellhead bore, when so lowered, and for sealing against the wellhead bore, when so supported, at least one opening through the body by-passing said sealing means, valve means mounted on the body for moving between positions opening and closing said bypass openings, and means for holding the valve means in open position to permit well fluid to pass therethrough, as the body is lowered into supported position, and for moving the valve means from open to closed position, when the body is so supported, so that, when the sealing means is sealed against the wellhead bore, the closure means on the preventer may be closed on the pipe string in order to enclose a space about the string vertically intermediate the body and closure means into which fluid under pressure may be introduced, and for moving the valve means from closed to open position, when the test is completed, to permit well fluid to pass through the by-pass opening as the body is lifted from supported position within the well bore, the bore through said body being open to flow upwardly therethrough so as to relieve test fluid pressure should it not be held by said sealing means.

2. Apparatus of the character defined in claim 1, wherein said body comprises an outer sleeve having means thereon landable in the wellhead bore. and a central portion releasably connected to the sleeve for vertical reciprocation therein. said central portion has a downwardly facing shoulder thereabout. said sleeve has an upwardly facing shoulder beneath the shoulder on the central portion. and said sealing means comprises a seal ring surrounding the central portion intermediate the shoulders in position to be forced into sealing engagement with the wellhead bore upon release of the connection of the central portion and the sleeve in response to landing of said sleeve in the wellhead bore and continued lowering of the central body with respect thereto.

3. Apparatus of the character defined in claim 1, wherein said body suspending and bore providing means comprises a tubular member extending therethrough. said valve means is carried by said tubular member. and said tubular member is movable vertically with respect to said body in order to move said valve means between open and closed position.

4. Apparatus of the character defined in claim 3, including at least one shear pin releasably connecting the tubular member to the body so as to hold the valve means in open position as the body is lowered into the well bore. and a shoulder on the tubular member for supporting the body therefrom as the tubular member is raised and lowered within from the well bore.

5. Apparatus of the character defined in claim 3. wherein there are a plurality of by-pass openings. and the valve means comprises a plate for covering all said openings in its closed position.

i i k i i

Claims

1. Apparatus for use in pressure testing a blowout preventer which includes a housing having a bore therethrough sealably connected to the upper end of a wellhead, with its bore forming an upward continuation of the bore through the wellhead, and closure means mounted within the housing for extension into the bore to seal about a pipe string therein, said apparatus comprising a body, means on the body for suspending it from a pipe string, so that it may be raised and lowered therewith within the bores, and providing a bore therethrough adapted to form a continuation of the lower end of the pipe string, when the body is so suspended, said body also having means thereon for supporting it within the wellhead bore, when so lowered, and for sealing against the wellhead bore, when so supported, at least one opening through the body by-passing said sealing means, valve means mounted on the body for moving between positions opening and closing said by-pass openings, and means for holding the valve means in open position to permit well fluid to pass therethrough, as the body is lowered into supported position, and for moving the valve means from open to closed position, when the body is so supported, so that, when the sealing means is sealed against the wellhead bore, the closure means on the preventer may be closed on the pipe string in order to enclose a space about the string vertically intermediate the body and closure means into which fluid under pressure may be introduced, and for moving the valve means from closed to open position, when the test is completed, to permit well fluid to pass through the by-pass opening as the body is lifted from supported position within the well bore, the bore through said body being open to flow upwardly therethrough so as to relieve test fluid pressure should it not be held by said sealing means.

2. Apparatus of the character defined in claim 1, wherein said body comprises an outer sleeve having means thereon landable in the wellhead bore, and a central portion releasably connected to the sleeve for vertical reciprocation therein, said central portion has a downwardly facing shoulder thereabout, said sleeve has an upwardly facing shoulder beneath the shoulder on the central portion, and said sealing means comprises a seal ring surrounding the central portion intermediate the shoulders in position to be forced into sealing engagement with the wellhead bore upon release of the connection of the central portion and the sleeve in response to landing of said sleeve in the wellhead bore and continued lowering of the central body with respect thereto.

3. Apparatus of the character defined in claim 1, wherein said body suspending and bore providing means comprises a tubular member extending therethrough, said valve means is carried by said tubular member, and said tubular member is movable vertically with respect to said body in order to move said valve means between open and closed position.

4. Apparatus of the character defined in claim 3, including at least one shear pin releasably connecting the tubular member to the body so as to hold the valve means in open position as the body is lowered into the well bore, and a shoulder on the tubular member for supporting the body therefrom as the tubular member is raised and lowered within from the well bore.

5. Apparatus of the character defined in claim 3, wherein there are a plurality of by-pass openings, and the valve mEans comprises a plate for covering all said openings in its closed position.