US3695349A

US3695349A - Well blowout preventer control pressure modulator

Info

Publication number: US3695349A
Application number: US21130A
Authority: US
Inventors: Fernando Murman; George E Lewis; Charles E O'brien
Original assignee: Hydril LLC
Current assignee: Hydril LLC
Priority date: 1970-03-19
Filing date: 1970-03-19
Publication date: 1972-10-03
Anticipated expiration: 1989-10-03
Also published as: GB1273946A; BE764590A; DE2113372C3; DE2113372A1; FR2085612A1; DE2113372B2; CA932265A; NL7103598A; FR2085612B1

Abstract

The constriction of a packer or other tool about a pipe string being run in a well is altered in such manner while a pipe joint is passing through the packer as to facilitate rapid running of the string in a well and to reduce wear of the packer.

Description

United States Patent [is] 3,695,349 Murman et a1.- [45] Oct. 3, 1972 [54] WELL BLOWOUT PREVENTER 3,103,976 9/1963 DeVries ..166/.6 CONTROL PRESSURE MODULATOR 1,894,912 1/ 1933 Otis 166/77 X Inventors: n o man a os ve des I Minor a 2,188,141 1/1940 Abercrombie ..25l/1 X Peninsula, George E. Lewls, Arcadkr Charles E 01mm Whittier 2,721,614 10/1955 Simmons ..166/77 X a ofcanf 3,207,221 9/ 1965' Cochran et a1. ..l66/88 X 1 3,215,203 11/1965 Sizer ..l66/77 [73] Assignee: Hydril Company, Los Angeles,

Calif. Primary Examiner-Marvin A. Champion Assistant Examiner-Richard E. Favreau [22] filed March 1970 Attorney-White, Haefliger and Bachand [21] Appl. No.: 21,130

[57] ABSTRACT [52] US. Cl. ..166/.5, 251/1, 166/84 The constriction of a packer or other tool about a pipe [51] Int. Cl. ..E2lb 33/035 string being run in a well is altered in such manner [58] Field of Search ....166/53, 84, 86, 75, 82; 251/1; while a pipe joint is passing through the packer as to 277/28, 34, 103, 73 facilitate rapid running of the string in a well and to reduce wear of the packer. [56] References Cited UNITED STATES PATENTS v 37 Claims, l2 Drawing Figures 3,533,468 10/1970 Lewis etal ..'.....251/1 X PATENTED T 3 SHEET 3 [IF 4 OPENlNG CHAMBER TO Fourz- WAY com-Q01. VALVE fxvvewrales.

END/V00 MueAm/v 050/1265 E. LEW/.5 (IE memes E. OB/Q/E/V ELL arowour PREVEN'IER comm. rnnssrm: MODULATOR BACKGROUND OF THE INVENTION This invention relates generally to the control totool engagement with vertically movable well strings, and more particularly concerns the reduction of resistance to vertical travel of such stringsthrough packers closed about such strings. r I

' lnwell drilling operations it is frequently the'practice to 'constrict a packer element, (as for example in a flow-out preventer) about the drill string so as to shutin the gas pressure in the wall annulus. Such constric- Preventer (Model GKI 5000) at only a few inches per second, whereas. the string'between successive joints may be traveled .at"several feetpersecond through the constricted packer. v

The above problem becomes extremely critical in off-shore, sub-sea packer installations where a drill string is suspended from a drilling barge. It is found that SUMMARY OF THE INVENTION Itis a major object of the invention to provide ap-' paratus ,and method for overcoming the above described problems. Basically, the method of the invention is applicableto a-system that includes packer means, typically-annular, that is laterally constricted to engage a well string being passed longitudinally I typical joint through the packer of a-Hydril Blow-out the constricted packer without substantially increased resistance to such passage, and without requiring reduction of speed of travel of the string, and also without materially increasing the rate of wear of the packer material.

In its apparatus aspects the invention comprises, in such a system as described, supply means to selectively supply actuating fluid pressure to the chambers; and modulator means in communication with the fluid pressure supply to the first chamber and operably to relieve such excess pressure development. Typically, the

modulator means is in operative communication with the second chamber to effect sudden fluid pressure increase in the latter in response to sudden excess pressure development in the first chamber. As will be seen, the modulator means may include a by-pass valve controlling fluid pressure communication to the second chamber, together with biasing means (as for example the pressure of control fluid stored in an accumulator) yieldably biasing the by-pass valve toward a position blocking communication of actuating fluid pressure from the first to the second chambers.

Additional objects include the provision of a control valve (as for example a four-way valve) for controlling supply fluid pressure alternately to the first and second chambers as described, that valve having a position in through thepacker, and means including a packer actuator forming a first chamber receiving fluid pressure acting to urge the actuator in a direction to effect such packer construction, and, a second chamber subsequently to receive fluid pressure acting to urge the actuator in a direction relieving packer constriction to allow expansion of the packer away from the string, the pressure in thefirst chamber being subjected to in crease to excessive level in response to engagement of an enlargement (such as a joint) in the string with the constricted packer and tending to expand same. The method steps include continuing the supply of actuating fluid pressure to the first chamber; and suddenly increasing the fluid pressure in the second chamber in response to the enlargement engagement with the packer. Typically, the sudden increase is effected by which it communicates the second chamber with an outlet via piping of such length that an actuating pressure wave passed by the by-pass valve is supplied to the second chamber prior to transmission to the outlet via the control valve; the location of the by-pass valve either outside or inside a housing for the packer; the provision of a signaling circuit comprising a switch operable in response to by-passing of fluid to the second chamber via the modulator means and a signaling device (as for example on a drilling barge) electrically connected in circuit with the switch. Accordingly, the operator may elevate or lower the pipe so that the switch is not operated in response to vertical stroking of the string due to wave action on the barge, whereby he is assured that pipe joints are not passing up and down through the constricted packer, reducing wear thereof. Finally, the invention is applicable to use with string engaging tools other than radially constrictable packers, i.e., for example pipe rams.

These and other objects and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following description and drawings, in which:

DRAWING DESCRIPTION FIG. 1 is an elevation showing a sub-sea well head assembly;

FIG. 2 is a vertical elevation, taken in section, show ing a preventer assembly in closed or actuated condition;

FIG. 3 is a view showing a control system for the preventer, or similar preventers;

FIG. 4 is an elevation taken in section through a control valve in the FIG. 3 system;

FIG. 5 is a view showing a manually operable system for the preventer;

A FIG. 6 is a fragmentary elevation showing a modifi- FIGS. -12 are sections showing modified control valves.

DETAILED DESCRIPTION Referring first to FIG. 1, the blow-out preventer assembly 10 is shown connected in a sub-sea stack 100 also including a series of ram-type preventers 101. A riser system 102 extends above the stack and is connected thereto by a well head connector 103. Riser pipe extends to the sea surface, and typically to a drilling barge 104 or other installation, and it is clear that wave action will cause the barge to move up and down, displacing suspended pipe up and down in the riser and the blow-out preventers.

. Turning to FIG. 2, the control head or preventer assembly, generally indicated at 10, includes a body member 11, having concentric bores l2, l3 and 14, which are of progressively increased diameters. Cap 16 is releasably held to the body member by screw thread connection 17 in such a position that the face 19 of cap flange 20 engages the upper end 21 of the body member 11, and cap and body member being packed off at 22. Cap 16 has a bore 23 which is of the same diameter and is concentric with body bore 12. Sunk in the upper face of cap 16 are bolt holes 24 for the attachment of equipment thereabove. The annular groove 25, in that upper face, is adapted to receive a sealing ring for sealing engagement with said equipment.

The neck 26 of body member 11 has an attachment flange 27 whereby connection is made through bolts 28 to the flange 29 or any other suitable fitting.

Cap 16 has an internal annular flange 35 which defines the downward continuation of bore 23, and a peripheral flange 36 which defines bore 37, said bore 37 being concentric with all the body-member bores identified above.

The body 11 has an annular, upstanding flange 38 which engages the packer actuating member 39 at 40 to limit the extent of downward movement of said member. The actuator 39 has a piston portion 41, having piston-fit in bore 14, and piston portion 42 which has piston-fit in bore 13. The actuator is extended upwardly at 43, extension 43 having piston-fit in the capflange bore 37. Sealing rings 44, 45 and 46 are provided between

piston portions

42, 41 and 43, respectively, and the respective cylinder defining walls which receive those portions.

Piston 41 divides body bore '14 into upper and lower cylinders or

pressure chambers

47 and 48,

ports

49 and 50 opening, respectively, from those chambers.

External pipes

51 and 52 open to

ports

49 and 50, respectively. Note that the outer diameters (14) of

chambers

47 and 48 are equal, and the inner diameters (l3) and 37 of these chambers may be equal, for balancing purposes. I

The actuator 39 has a downwardly and inwardly tapering conical bore 53, and the actuator portion 43 which defines this bore may be considered broadly as an internal, conical wedge, or as a packer-constricting element.

Packer P includes a massive annulus or sleeve 55 of an elastomer and, preferably, resilient material such as rubber or Neoprene. In most instances, it is intended that a single packer be adapted for repeated opening and closing operations, and therefore it is preferable that it have relatively high resilient characteristics, so it may be self-restoring to open position when the constricting force is removed. From this point on in the description, it will be assumed that the packer has such resilient characteristics, but this assumption is not considered as limitative on my broader claims. It has been found that rubber having a durometer hardness of about 75 is suitable for general use in my packer but, again, this specification of relative hardness is not to be considered as limitative. The packer is shown as an unsplit, continuous annulus, but it will be understood that the disclosure is not limited to a packer wherein there is no split, so long as there is no angularly extending gap interrupting the continuity of the packer at times when it is inwardly contracted into sealing engagement with members positioned within its bore.

Included in the make-up of the packer is a series of rigid, rubber-flow-control elements 56. These elements may take different forms and still lie within the scope of my broader claims, but I will first describe the preferred form of elements which has individual features of advantage. These rigid control elements are individually movable bodily with the rubber in its movement of radial contraction and expantion and also, to a limited extent, movable individually with respect to the rubber as will later appear. Taken together, the rigid control elements may be considered as a radially expansible and contractible armature embedded and bonded within annulus 55.

Molded annulus 55 has an outer conical face 57 which is complementary to actuator bore 53, and a bore 58 which has a central, substantially cylindrical portion 59 and oppositely inclining upper and

lower portions

60 and 61, respectively; the outward flare, in each case being toward the associated end of the annulus.

It will be seen that each element 56 comprises top and

bottom plates

63 and 64, respectively, rigidly connected by vertical rib 65, the outer faces 66 of the plates and the outer face 67 of the rib having substantially the same degree of taper as bore 53 and annulus face 57. Or

plates

63, 64 may be considered as transverse flanges on rib 65. Elements 56, which may be of steel, bronze, or any other suitable rigid material, are preferably positioned in the rubber at the time of molding and, preferably, the rubber and the elements are bonded together by the use of suitable adhesive during the molding process. The plates of the control elements are sectorial in shape, as viewed in plan, and are arranged in a circular series, with spaces left between the opposing side edges of the plates, both top and bottom. The plates are so sized that the two opposed sides edges of adjacent elements are spaced apart, it following that as the elements move radially inward, the spaces between these, will diminish to fonn a line contact from end to end of the plates. This will prevent the rubber which will flow during the constriction of the annulus from being pinched off at the radially inward ends of the plates.

The annulus 55 is molded so its outer annular portion 72 projects radially outward beyond the outer faces 66 of the plates, it following that these metallic faces do not engage the wall of actuator bore 53. For purposes of later description, annular portion 72 is considered as being that portion which extends radially from face 57 to the outer faces 67 of ribs 65.

The packer is lowered; while cap 16 is detached; into the position of FIG. 2, the actuator 39 then being in the fully down positiomand the annulus 55 nicely fitting the upper portion of bore 53 without requiring appreciable radialconstriction of the annulus. For positively limiting the downward movement of the annulus, a stop is provided in the form of tube 74 which is retained in housing bore .15. The upper end of thetube provides the, packer stop. The bore 75 of this tube is of the same diameteras bores 12 and 23,-and the tube is annularly spaced from both piston portion 42-and the lower end of actuator wedge-portion 43.-Ports 76 open from bore 75 to chamber 77, while latter is annularly defined by the tube and the sleeve 80, there being a seal at 78.

When cap '16 is subsequently secured in .place, its horizontal under-surface 79 providesa stop for limiting upward movement of the packer, the upper plates 63 of control elements 56 sliding over this surface" as the packer is radially constricted or expanded. Tube end and cap surface-79thus form vertically spaced stops which prevent appreciable vertical movement of the packer with relationto the body member 11.

.It will be seen that the radial constriction of the packer is accomplished by virtue of relative vertical movement between the packerand the actuator. While the illustrated embodiments show this relative movement as brought about by holding the packer against vertical movement with respect to the body member and then moving the actuator vertically with respect to the housing and packer, it will be understood the arrangement and operation may be reversed.

The sleeve 80 may be considered as part of the housing structure 11, to which it is retained by the faster 81. The sleeve 80 and body 11, together with actuator piston portion 42 from a" third chamber 82 to receive control pressure fluid (as via porting 83 and pipe 84) acting to urge the actuator upwardly in at least partly counterbalancing relation to downward force exertion on the actuator. In particular, such downward force to bl so counteracted maytypically result from the static pressure p of a column of drilling mud in the annulus 85 outside the drill pipe 86, such mud circulating downwardly in that pipe to the bit, and rising in the annulus.

FIG. 1 shows the riser 87 within which the mud flows to the surface. The mud pressure is applied to the packer P tending to expand it, and downward thrust is thereby transferred to the actuator 39 across, enlarged tapered surfaces 57 and 53, when the packer is closing in the well. See in this regard co-pending application Ser. No. 785,891, entitled, Well Pressure Compensated Well Blowout Preventer wherein the supply of counterbalancing fluid pressure to chamber 82 via pipe 84 is discussed.

Extending the description to FIG. 3, a gas pressure vessel 90 is shown as communicating with

pipes

51 and 52 via a suitable pressure regulator 91 and four-way valve 92. In one position of the latter, as illustrated, pressure fluid is delivered to pipe 52 for closing the preventer packer, and pressure fluid in pipe 51 is exhausted at 93 to the sea or returned to the surface. In

the alternate position of the valve 92, pressurevfluid is delivered to pipe 51 for opening the preventer packer, and fluid in pipe 52 is exhausted to the seaor returned to the surface. As explained in the co-pending application referred to above, counterbalancing fluid pressure may also be supplied to chamber 82 via pipe 84. Controls for the regulator 91 and valve 92 are indicated at 94 and 95, and may be electrically operated from the surface.

Coming now to that portion of the description highlighting the invention, it will be noted hat the string 86 may typically have connectors or collars interconnecting the string pipelengths 111, the connectors being of larger diameter than such pipe. It is often desired to maintain the packer closed about the pipe while the latter is run longitudinally into or out of the well or while the pipe moves up and down due to wave action onthe barge, as referred to; and it isfound that rapid vertical displacement of the connectors through the closed packer tends to excessively wear the packer rubber necessitating its replacement at great expense. In this-regard, with several hundred pounds of closing fluid pressure applied to chamber 48, excessive pressure builds up in the latter as the connector 110 engages the closed packer and attempts to expand it and thereby urge the actuator 39 downwardly.

In accordance with the invention, modulator means is provided in this environment, and in communication with the pressure supply to closing (i.e. first) chamber 48, for relieving the excess pressure development in that chamber, that developed pressure at times being greater than 1,500 p.s.i. As will be seen, the relief is such as to enable the enlarged connector to pass without difficulty through the packer, i.e., without excessively wearing the packer while at the same time the packer remains in closed and annular sealingengagement with the connector and pipe string vertical speed not being reduced during such passage. Typically, a bypass passage or pipe may be provided as at 1 13 communicating between the

chambers

47 and 48, as for example via

pipes

51 and 52, and the modulator means may comprise a check valve unit as at 114 controlling the by-passing of excess fluid pressure from closing chamber 48 to opening chamber 47.

FIG. 4 shows one form of modulating check valve unit which also accommodates biasing to control the pressure level at which such by-passing occurs. lt comprises a body 115 having a threaded inlet 116 for bypass pipe branch 117 connected to pipe 52, and a threaded outlet 118 to receive the terminal of by-pass pipe 113. Received within the body bore 119 is a seat ring 120 against which a valving stopper such as a ball 121 is urged by a plunger stem 122. The plunger or piston body 123 is urged by spring 124 toward the ball, theopposite end of the spring being seated by a plug 125 having threaded reception at 126 in the body 1 15. In this regard, the effective area of the piston 123 may be equal to or greater than the effective area of the opening 120a defined by the ball seat, so that the ball will be held closed against the seat prior to pressure increase in line 117 created by attempted passage of a connector through the closed packer.

Plunger 122 is also urged toward the ball 121 by control fluid pressure in chamber 127, and supplied from an accumulator 128 via piping 129. The accumulator receives fluid under pressure from the line 130 connecting the discharge side of the regulator 91 with the control valve 92, there being a check valve 131 in line 130 downstream of the location 132 at which the accumulator communicates with line 130 via branch 133. As a result, the control fluid pressure supplied by bypass valve chamber 127 remains at a level in part determined by the regulator 91, the excess pressure developing in the preventer closing chamber 48 being blocked by check valve 131 from communication to the accumulator. Check valve 131 is not needed if

lines

129 and 250 or 250a are sufficiently long, as for example where they extend from the surface.

When that excess pressure reaches a level determined by the regulated level and the tension of spring 124, the by-pass valve stopper or ball 121 opens and the excess pressure is immediately communicated to the opening chamber 47. Relief of pressure'build-up in closing chamber 48 may typically occur within less than a second following its sudden build-up. Also, the extent of relief may be such that the connector freely passes through the packer, with clearance permitting slight fluid leakage th'erebetween, the advantages being minimum wear of the packer and rapid passage of the connector therethrough. In FIG. 3 control valve configuration, chamber 47 remains in communication via elongated pipe 134 with the discharge or outlet point 135, so that the excess pressure may bleed at a slower rate to the discharge, due to the restriction to flow imposed by the pipe 134.-ln other words, when valve stopper 121 opens, the excess pressure wave is first communicated to chamber 47, and later to the discharge, causing a downward force on the piston 39 to open the packer P to allow free passage of tool joint 110 through the packer. Note that the pressure in the opening chamber 47 and in valve body bore 119 typically will not be less than that of the sea water at the sub-sea level of the equipment, during the time valve 92 is in the position shown in FIG. 3. Accordingly, the pressure delivered by the regulator 91 to close the packer about the string 86 must be substantially greater than the sub-sea pressure at the equipment level. Regulator 91 may be conventional, and include a valve controlling diaphragm exposed to pressure in line 91a and to spring tension adjusted by control 94. Finally, accumulator 128 may be made integral with the modulator valve unit 114. Check valve 131 may be eliminated if 5 line 250 between the accumulator and the by-pass valve is of length such that the excess pressure wave is by-passed at 114 prior to return via line 250 to the aceumulator.

I FIG 10 illustrates the provision of an adjustable insert 230 threaded at 231 into plug a corresponding to plug 125 in FIG. 4. Rotation of the insert adjusts the tension in spring 124a, for control of by-passing pressure.

A further feature of the invention concerns the provision of a signaling circuit comprising a switch or other means indicated at in FIG. 3 operable in response to by-passing of the fluid by valve 114, and a signaling device 141 (see FIG. 1) electrically connected in circuit with the switch, as via cable 142. The switch may be pressure responsive and in communication with fluid pressure in line 113. Accordingly, the signaling circuit enables detection by the operator at the surface of an increase in pressure in the closing chamber 48 to excessive level, as results from passage of a connector 110 into or through the closed packer annulus, wave action of the drilling barge for example lifting or loweringthe pipe to effect this condition. He may then adjust the pipe string as by lifting or lowering same so as to obviate the condition, at which point the signaling device 141 at the surface is no longer actuated on and off at wave cresting or troughing intervals, whereby wear of the packer is substantially reduced.

FlGQS illustrates a modified system characterized by hand operation, or hand-controlled operation of one or more of the

valves

150, and 151. In one position of four-way valve 151, actuating fluid pressure is applied to the packer closing chamber, (corresponding to chamber 48) in the preventer assembly 153; and likewise, in the alternate position of valve 151, actuating fluid pressure is applied to the packer opening chamber (corresponding to chamber 47). The above assumes that by-pass valve remains closed. Upon the occurrence of excess pressure in the closing chamber, as communicated by the gauge 155, the operator may momentarily open the by-pass valve 150 to bleed the excess pressure developed in the closing chamber (as by passage of a connector 156 through the closed packer) to the opening chamber, for the purpose and with the results described above.

The by-passing function may alternatively be effected within the preventer housing as by a valve 160 protectively housed in the wall of the housing 11a of the blow-out preventer assembly, in FIG. 6. Control pressure is led to the valve biasing piston 123a as via a pipe 161, the piston being retained in an insert 162. Bypass ducts in the wall are seen at 163 and 164 communicating with chambers 48a and 470 at opposite sides of the actuator piston 41a.

Ducts

49a and 50a correspond to ducts 49 and 50in FIG. 2.

Further, as seen in FlG. 3, the by-passing function may be supplemented by use of a modulating valve similar to valve 114, and connected between pipe 84 and pipe 51, to by-pass excessive pressure in chamber 82 to the opening chamber.

Referring to FIG. 7, isolation is there provided between the opening and closing pressure lines 51a and 52a connected to the housing 11 and in FIG. 2, and the modulated means generally indicated at 199, the latter functioning to relieve excess pressure development in the closing chamber of the preventer unit 10. Means 199, which may be supplied as a separate and complete unit to be operatively combined with the preventer, includes the modulator or by-pass valve 200 having the same mode of operation as that shown in FIG. 4. Pressure from the closing chamber of the preventer is supplied via line 201 to the inlet side of the valve; pressure from the outlet side of the valve is communicated to the preventer opening chamber via line 202; and control pressure from line 201 is normally supplied to the piston side of the valve 200 via line 203, shuttle valve unit 204, and line 205. An accumulator 206 is also connected with line 205, and line 205 contains an orifice restriction at 198.

If pressure in line 201 increases due to attempted passage of the pipe connector 207 through the packer within the preventer 10, the by-pass valve opens and the excess pressure is supplied via line 202 to the opening chamber, as previously described. Any excess then flows via that chamber to line 510 leading to the fourway valve and then to the surface or to the sea. lf presclosing chamber because shuttle ball 204a will be displaced from seat 209 to seat 208, in chamber 308. Restriction 198 prevents sudden loss of accumulator pressure to

exhausting line

201 or 202, while ball 204a shifts position to block such loss. Note the accumulator pressure equals that in

line

201 or 202 to which it is connected. t Referring to FIG. 8,"the construction is the same as in FIG. 7, excepting that the shuttle valve is eliminated, and instead controlpressure is supplied to the accumulator 206 and to the piston side of the by-pass valve 200 from a surface control unit 210, via piping 211. This adds versatility, and permits the surface operator to determine when the modulator means is to be operative and inoperative.- For example, he, may supply suflicient control pressure to prevent the'by pass valve from operating should thatbe desired.

FIG. 9 is similarlto FIG. 8, and illustrates a modified system'characterized by remote control of the biasing pressure applied to the piston chamber in the valve 200, and from a pressure source different from that used to operate the preventer. The by-pass pressure level is determined by the adjustment at 213 of pressure regulator 212, and that level could be substantially greater than the pressure supplied to the preventer via line 217 at times when the by-pass valve is to remain in- I operative. Line 214 connects an accumulator 215 with the regulator, and the line 216 connects the regulator with the control piston side of the by-pass valve. Pressure from an accumulator 218 is supplied to line 217 via regulator 219 and four-way valve 220. When valve 220 is in the alternate position, pressure is supplied via line 221 to the preventer opening chamber. The provision of two separated pressure sources 215 and 218 makes unnecessary the check valve seen at 131 in FIG. 3, isolation being provided at the pressure source.

Referring back to FIG. 8, a pressure differential switch 320 (or flow switch) is located in a branch line 321 connected into line 202 at opposite sides of the orifice 222. Electrical wiring 323 connects the switch with a surface indicator as at 141 in FIG. 1, which signals when pressure from the closing chamber is by-passed to the opening chamber. The orifice 222 provides an increased differential pressure thereacross in response to the by-passing of increased pressure to the opening chamber, and sufficient to operate the switch. In FIG. 9, a signaling pressure switch 230 is connected in the discharge line 231 from the four-way valve 220, and upstream of the restriction means 232 in that line, the switch being operated when the excess pressure from line 201 is by passed at 200 to line 202, then to line 221, the four-way valve and line 231.

FIG. 11 illustrates the carriage by the actuator 39a of the by-pass valve unit 235. The latter may for example include the valve stopper such as ball 236 biased against seat ring 237 by the yieldable biasing means in the form of a compression spring 238. The latter is retained within a plug 239 threaded into the

actuator piston

240 and 241, and it acts on the ball 236 via a plunger 242 slidable within a bore 243 in the plug. Fluid by-passed by the ball escapes from closing chamber 244 to the opening chamber 245, via ducts 246 and 247 in the actuator piston. A telescoping hydraulic control connection to the by-pass valve may take the form of a hollow pin 248 sealed at 248a and carried by the actuator piston 251 to slide up and down in the pin bore 249 formed in the body 250, corresponding to housing 11 in FIG. 2. This arrangement provides a hydraulic connection from port 258 through .

ports

300 and 301 and through which control fluid pressure enters the control fluid chamber 249a to urge the piston 242 toward the ball 236. Actuator 251 also corresponds to actuator 39 in FIG. 2. Opening pressure is led via porting 253 to the opening chamber 245.

FIG. 12 illustrates a modified modulator valve unit 260 incorporated in a body 261 which also carries a check valve 262 (corresponding to check valve 131 in FIG. 3) and an accumulator 263 (corresponding to accumulator 128 in FIG. 3). The check valve unit 262 includes a ball check 264 spring urged at 265 against a seat ring 266,'and corresponds to check valve 131 of FIG. 3. When valve 264 opens, pressure is applied to the four-way valve (not shown) which may have a position applying pressure to port 272 to be described.

Pressure is communicated to the accumulator 263 via the porting 267 and 268, such pressure also being communicated to the control piston 269 acting via plunger 270 to bias the modulator valve ball 271 against seat ring 271a. When the ball 271 is displaced upwardly off the seat, excess fluid pressure in port 272 (communicating with the closing chamber) escapes to side port 273 and to the openingchamber at the actuator piston in the manner as described in FIG. 3. A spring 274 assists in holding the ball 271 closed. Note insert legs 275 connected to the ring 271a, and retained by insert sleeve 276 defining the bore 277 in which the piston 269 works. Thus, ring 271a is held by legs 275 in sealing position.

Provision is also made for operation of a switch in a circuit controlling a suitable indicator, as at the surface in an off-shore embodiment. The switch arm in this case consists of a rod 278 carried by the piston 269 and projecting vertically for engagement with a terminal contact 279 upon upward displacement of the piston by the ball 271, to complete the indicator circuit. Contact 279 is urged downwardly by a spring 280 adapted to yield upwardly as the ball 271 lifts the piston and rod 278, insulation 281 and 282 confining the contact and spring against electrical contact with the insert 283 in which these elements are housed. The insert in turn fits within bore 284 within receptacle 285 carried by the body 261. The spring has electrical circuit communication via terminal 286 with the indicator indicated schematically at 287. I

The accumulator unit 263 may comprise a piston 290 slidable in bore 291 to compress gas in chamber 292 in response to increased fluid pressure transmission to chamber 293.

The apparatus of the invention may be used in either land or sub-sea installations. Also, the apparatus works equally well whether the pipe string is being run into or out of a well. Further, after relief of excess pressure in the closing chamber associated with passing of the pipe joint through the packer, the modulating valve closes and the original conditions of packer constriction about the pipe string are restored.

What is claimed is:

1. ln a system that includes housing structure for passing a well string vertically therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the fluid in the first chamber being subject to excess pressure development in response to engagement of a longitudinally passing string enlargement with the tool tending to displace the latter and the actuator, the combination comprising a. supply means to selectively supply actuating fluid pressure to said chambers, and

b. modulator means in communication with the fluid pressure supply to the first chamber and operable to relieve said excess pressure development therein in response to entry of said enlargement into the tool.

2. The combination of claim 1 wherein said tool comprises a packer annulus which is radially constrictable by the actuator, and which is expansible radially in response to string joint passage forcibly therethrough.

3. In a system that includes housing structure for passing a well string vertically therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the fluid in the first chamber being subject to excess pressure development in response to engagement of a longitudinally passing string enlargement with the tool tending to displace the latter and the actuator, the combination comprising a. supply means to selectively supply actuating fluid pressure to said chambers, and

b. modulator means in communication with the fluid pressure supply to the first chamber and operable to relieve said excess pressure development therein,

c. the modulator means being in operative communication with the second chamber to effect a pressure increase therein in response to excess pressure development in the first chamber.

4. In a system that includes housing structure for passing a well string vertically therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the fluid in the first chamber being subject to excess pressure development in response to engagement of a longitudinally passing string enlargement with the tool tending to displace the latter and the actuator, the combination comprising a. supply means to selectively supply actuating fluid pressure to said chambers, and

c. said modulator means including a pressure relief valve communicating with the .fluid pressure supplied the first chamber.

5. In a system that includes housing structure for passing a well string vertically therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the fluid in the first chamber being subject to excess pressure development in response to engagement of a longitudinally passing string enlargement with the tool tending to displace the latter and the actuator, the combination comprising a. supply means to selectively supply actuating fluid pressure to said chambers,

b. modulator means in communication with the fluid pressure supply to the first chamber and operable to relieve said excess pressure development therein, and

c. a passage communicating between said chambers, said modulator means controlling fluid pressure communication from the first to the second chambers for effecting said relief of excess pressure development in the first chamber.

6. The combination of claim 5 including a signaling circuit comprising a switch operable in response to bypassing of fluid to the second chamber via the modulator means, and a signaling device electrically connected in circuit with the switch.

7. The combination of claim 6 including said well string suspended by a vessel to hang in the ocean and in a well below the ocean floor, said device being on the vessel and said switch being at a stack of well head equipment at the ocean floor.

8. The combination of claim 6 wherein the switch includes a spring-urged contact adapted to be displaced to increase the spring tension in response to said fluid by-passing.

9. The combination of claim 5 wherein said modulator means includes a by-pass valve controlling said fluid pressure communication from the first to the second chambers.

10. The combination of claim 9 wherein said by-pass valve is outside the housing.

11. The combination of claim 9 wherein said modulator means also includes biasing means yieldably biasing the valve toward a position blocking said fluid pressure communication from the first to the second chambers.

12. The combination of claim 11 wherein said biasing means includes control fluid pressure from a source out of communication with said chambers.

13. The combination of claim 11 wherein said biasing means comprises control fluid pressure, and a piston responsive to said control fluid pressure to transmit biasing force to the valve.

14. The combination of claim 13 in which said biasing means also includes a spring under tension, and means to adjust said tension.

15. The combination of claim 13 including piping communicating the modulator means and said first chamber with the accumulator and of length such that an excess pressure wave from the first chamber is bypassed by said by-pass valve toward the second chamber prior to transmission of the wave via said piping to said accumulator.

16. The combination of claim 13 wherein said supply means includes a control valve having one position in which actuating fluid pressure is supplied to the first chamber but not to the second chamber, and a second position in which actuating fluid pressure is supplied to the second chamber but not to the first chamber.

17. The combination of claim 16 in which said control valve in said first position communicates the second chamber with an outlet and via piping of such length that an actuating fluid pressure wave passed by the by-pass valve is supplied to the second chamber prior to transmission to the outlet via the control valve.

18. The combination of claim 16 wherein said supply means includes a source of actuating fluid pressure and a pressure regulator connected between said source and the control valve.

[9. The combination of 'claim 16 including an accumulator supplying said control fluid pressure.

20(The combination of claim l9including a support body containing said accumulator and said by-pass valve.

21. The combination of claim 20 including a check valve contained by said body and operable to transmit pressure from the accumulator to said control valve but blocking reverse transmission therebetween.

22. The combination of claim 9 wherein said by-pass valve in inside the housing. 23. The combination of claim 22 wherein said bypass valve is carried by the actuator.

24. The combination of claim 23 wherein the modulator means also includes yieladable biasing means biasing the valve toward a position blocking fluid pressure communication from the first to the second chambers.

25. The combination of claim 23 including a telescopic connection between the actuator and housing structure and defining porting through which control fluid pressureis transmissible to a biasing piston acting to biasthe by-pass valve toward a position blocking said fluid pressure communication from the first to the second chambers.

26. For use in a system that includes housing structure for passing a well string vertically therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the pressure in the first chamber being subject to increase to excessive levels in response to engagement of a vertically passing string enlargement with the tool tendingto displace the latter and the actuator, the combination comprising a. supply means to selectively supply actuating fluid pressure to the chambers, and

b, modulator means operable, while actuating fluid pressure is being supplied tothe first chamber, to increase the fluid pressure in the second chamber and in response to displacement of the tool relatively away from the string so as to cause the actuator to move toward the interior of the first chamber.

27. The combination of claim 26 wherein said modulator means is in fluid pressure by-passing communication with said chambers in response to said tool displacement.

28. In the operation of a system that comprises annular packer means which is radially forcibly constricted to engage a well string being passed longitudinally therethrough, and means including a packer actuator forming a first chamber receiving fluid pressure acting to urge the actuator in a direction to effect said packer constriction, and a second chamber subsequently to receive fluid pressure acting to urge the actuator in a direction relieving packer constriction to allow radial expansion of the packer away from the string, the pressure in the first chamber being subjected to increase to excessive level in response to engagement of an enlargement on the string with the constricted packer and tending to expand the packer, the steps that include a. continuing the supply of actuating fluid pressure to the first chamber, and

b. suddenly increasing the fluid pressure in the second chamber in response to said engagement.

29. The method of claim 28 wherein said sudden increase of fluid pressure in the second chamber is effected by controllably by-passing to the second chamber excess pressurized fluid from the first chamber.

30. The method of claim 29 wherein said by-passing is effected in response to detection of an increase of pressure in the first chamber to said excessive level.

31. For use in a sub-sea system that includes housing structure for passing a well string longitudinally therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the pressure in the first chamber being subject to increase to excessive levels in response to engagement of a longitudinally passing string enlargement with the tool tending to displace the latter and the actuator, the combination comprising modulator means operable, while actuating fluid pressure is being supplied to the first chamber, to increase the fluid pressure in the second chamber and in response to increase of fluid pressure in the first chamber caused by force transmission from the enlargement to the actuator via the tool, said modulator means including a bypass valve, biasing means including an accumulator for biasing the valve toward a position blocking actuating fluid pressure communication from the first to the second chambers, a first pipe to communicate the inlet side of the by-pass valve with the first chamber, a second pipe to communicate the outlet side of the bypass valve with the second chamber, and means to controllably communicate fluid pressure to said accumulator to supply said control fluid pressure.

32. The combination of claim 31 wherein said last named means comprises a valve operable to communicate fluid pressure from said first pipe to said accumulator when the pressure in said first chamber increases to said excessive level, and to communicate fluid pressure from said second pipe to said accumulator in response to fluid pressure communication to said second chamber tending to hold said by-pass valve closed.

33. The combination of claim 31 wherein said last named means comprises a surface control, and an elongated pipe communicating said control with said accumulator.

34. The combination of claim 31 including a pressure differential switch connected across an orifice in said second pipe, said switch being operable to electrically control an indicator at the surface.

35. The combination of claim 31 including a fourway valve connected with said first and second pipes to selectively control actuating pressure supply thereto, the four-way valve having an outlet to which another pipe is connected to pass fluid exhausted from one of the first and second chambers, and a pressure switch connected in said other pipe.

36. ln the operation of offshore drilling equipment wherein a pipe string extends longitudinally through a closed blow-out preventer at a sub-sea location, the preventer containing a fluid pressure chamber, the string including connectors of larger diameter than the pipe diameter, the steps that include a. effecting longitudinal displacement of the pipe,

b. detecting pressure change in said chamber resulting from the movement of a connector into engagement with the sub-sea closed preventer, and

c. adjusting the pipe string longitudinally to move the connector away from the preventer.

37. The method of claim 36 wherein the equipment includes a drilling barge from which the string is suspended to be subject to up and down displacement due to wave action, said adjustment step being carried out to an extent preventing subsequent engagement of the connector with the closed preventer due to said up and down displacement.

Claims

1. In a system that includes housing structure for passing a well string vertically therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the fluid in the first chamber being subject to excess pressure development in response to engagement of a longitudinally passing string enlargement with the tool tending to displace the latter and the actuator, the combination comprising a. supply means to selectively supply actuating fluid pressure to said chambers, and b. modulator means in communication with the fluid pressure supply to the first chamber and operable to relieve said excess pressure development therein in response to entry of said enlargement into the tool.

3. In a system that includes housing structure for passing a well string vertically therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the fluid in the first chamber being subject to excess pressure development in response to engagement of a longitudinally passing string enlargement with the tool tending to displace the latter and the actuator, the combination comprising a. supply means to selectively supply actuating fluid pressure to said chambers, and b. modulator means in communication with the fluid pressure supply to the first chamber and operable to relieve said excess pressure development therein, c. the modulator means being in operative communication with the second chamber to effect a pressure increase therein in response to excess pressure development in the first chamber.

4. In a system that includes housing structure for passing a well string vertically therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the fluid in the first chamber being subject to excess pressure development in response to engagement of a longitudinally passing string enlargement with the tool tending to displace the latter and the actuator, the combination comprising a. supply means to selectively supply actuating fluid pressure to said chambers, and b. modulator means in communication with the fluid pressure supply to the first chamber and operable to relieve said excess pressure development therein, c. said modulator means including a pressure relief valve communicating with the fluid pressure supplied the first chamber.

5. In a system that includes housing structure for passing a well string vertically therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the fluid in the first chamber being subject to excess pressure development in response to engagement of a longitudinally passing string enlargement with the tool tending to displace the latter and the actuator, the combination comprising a. supply means to selectively supply actuating fluid pressure to said chambers, b. modulator means in communication with the fluid pressure supply to the first chamber and operable to relieve said excess pressure development therein, and c. a passage communicating between said chambers, said modulator means controlling fluid pressure communication from the first to the second chambers for effecting said relief of excess pressure development in the first chamber.

6. The combination of claim 5 including a signaling circuit comprising a switch operable in response to by-passing of fluid to the second chamber via the modulator means, and a signaling device electrically connected in circuit with the switch.

15. The combination of claim 13 including piping communicating the modulator means and said first chamber with the accumulator and of length such that an excess pressure wave from the first chamber is by-passed by said by-pass valve toward the second chamber prior to transmission of the wave via said piping to said accumulator.

19. The combination of claim 16 including an accumulator supplying said control fluid pressure.

20. The combination of claim 19 including a support body containing said accumulator and said by-pass valve.

22. The combination of claim 9 wherein said by-pass valve in inside the housing.

23. The combination of claim 22 wherein said by-pass valve is carried by the actuator.

25. The combination of claim 23 including a telescopic connection between the actuator and housing structure and defining porting through which control fluid pressure is transmissible to a biasing piston acting to bias the by-pass valve toward a position blocking said fluid pressure communication from the first to the second chambers.

26. For use in a system that includes housing structure for passing a well string vertically therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the pressure in the first chamber being subject to increase to excessive levels in response to engagement of a vertically passing string enlargement with the tool tending to displace the latter and the actuator, the combination comprising a. supply means to selectively supply actuating fluid pressure to the chambers, and b. modulator means operable, while actuating fluid pressure is being supplied to the first chamber, to increase the fluid pressure in the second chamber and in response to displacement of the tool relatively away from the string so as to cause the actuator to move toward The interior of the first chamber.

28. In the operation of a system that comprises annular packer means which is radially forcibly constricted to engage a well string being passed longitudinally therethrough, and means including a packer actuator forming a first chamber receiving fluid pressure acting to urge the actuator in a direction to effect said packer constriction, and a second chamber subsequently to receive fluid pressure acting to urge the actuator in a direction relieving packer constriction to allow radial expansion of the packer away from the string, the pressure in the first chamber being subjected to increase to excessive level in response to engagement of an enlargement on the string with the constricted packer and tending to expand the packer, the steps that include a. continuing the supply of actuating fluid pressure to the first chamber, and b. suddenly increasing the fluid pressure in the second chamber in response to said engagement.

31. For use in a sub-sea system that includes housing structure for passing a well string longitudinally therethrough, a string engaging tool movable generally laterally in the housing toward and away from the string, and a fluid pressure responsive actuator for the tool, there being first and second chambers in the housing to receive fluid pressure acting to urge the actuator in opposite directions, the pressure in the first chamber being subject to increase to excessive levels in response to engagement of a longitudinally passing string enlargement with the tool tending to displace the latter and the actuator, the combination comprising modulator means operable, while actuating fluid pressure is being supplied to the first chamber, to increase the fluid pressure in the second chamber and in response to increase of fluid pressure in the first chamber caused by force transmission from the enlargement to the actuator via the tool, said modulator means including a by-pass valve, biasing means including an accumulator for biasing the valve toward a position blocking actuating fluid pressure communication from the first to the second chambers, a first pipe to communicate the inlet side of the by-pass valve with the first chamber, a second pipe to communicate the outlet side of the by-pass valve with the second chamber, and means to controllably communicate fluid pressure to said accumulator to supply said control fluid pressure.

35. The combination of claim 31 including a four-way valve connected with said first and second pipes to selectively control actuating pressure supply thereto, the four-way valve having an outlet to which another pipe is connected to pass fluid exhausted from one of the first and seCond chambers, and a pressure switch connected in said other pipe.

36. In the operation of offshore drilling equipment wherein a pipe string extends longitudinally through a closed blow-out preventer at a sub-sea location, the preventer containing a fluid pressure chamber, the string including connectors of larger diameter than the pipe diameter, the steps that include a. effecting longitudinal displacement of the pipe, b. detecting pressure change in said chamber resulting from the movement of a connector into engagement with the sub-sea closed preventer, and c. adjusting the pipe string longitudinally to move the connector away from the preventer.