US3065793A - Apparatus for shutting off wells - Google Patents

Description

Nov. 27, 1962 J. s. PAGE 3,065,793

' APPARATUS FOR SHUTTING OFF WELLS Filed July l, 1957 2 Sheets-Sheet 1 ZQ Ja Nov. 27, 1962 J. s. PAGE APPARATUS FOR SHUTTING oFF WELLS 2 Sheets-Sheet 2 Filed July l, 1957 n INVENTOR. .fo//A/ .5'. .P465

B @QM www United States Patent O fornia Filed July 1, i957, Ser'. No. 669,043 16 Claims. (Cl. Mon-72) The present invention relates to a novel apparatus for producing oil and/or gas wells.

In the production of oil and gas wells it frequently becomes highly desirable to shut olf the flow of production uid. In recent years, with the advent of more and more offshore Wells, that is, wells which are drilled in earth formations which are submerged under water, the need for safety measures for preventing flowing of such an underwater well upon damage to the platform has become apparent. Substantial losses have been suffered in instances where offshore platforms have become damaged by storms and battered or rammed by floating, tide and Wind driven vessels and the like.

With conventional well head structures, if an oifshore platform were caused to shift on its pilings, rupture of the casing or the production tubing or both may result. Under such circumstances, the well would be free to iiow out of control until such flow could be arrested. The task of shutting off the flow of such a well, particularly if the break be located at some depth in the water is diiiicult and time consuming. Indeed, the task might well be impossible for a substantial period of time, thus resulting in the loss of huge quantities of production fluids and in tremendous expenses in repairing the damage.

Moreover, in the production of conventional land wells, as Well as offshore wells, it frequently becomes necessary to shut off the flow of production fluid for other reasons. For instance, if a flow line leading from the well to storage facilities should become damaged, or if an excessive well pressure should develop, it would be highly desirable to shut oil the flow of the well. Also, corrosion or other damage of the casing with ultimate breakage or leakage necessitates shutting in the Well.

The present invention contemplates and has as an object the provision of a means for shutting off a well responsive to certain emergency conditions as aforesaid, while leaving the production tubing and the casing free of objectionable obstructions which otherwise would prevent or hinder the performance of conventional downhole wire line services or would preclude normal production rates, and without necessitating smothering of the well as by pumping heavy mud down into the well.

As a further object, the invention contemplates an apparatus for producing oil and/or gas wells, wherein a packer is set down in the Well between the casing and the production tubing, a barrier being provided at the upper extremity of the casing annulus to prevent the direct flow of production iluid from the tubing into the annulus, and fluid under pressure from an auxiliary source or from the production fluid is fed to the annulus between the casing and tubing between the packer and the barrier, the tubing having a uid pressure operated shut oif valve, and the valve being maintained in an open position by such fluid pressure in the annulus above the packer, but closing automatically upon drop of such annulus pressure below production fluid pressure, whereby the ow of production fluid through the tubing Will be halted.

Another object is to provide an apparatus as aforesaid, wherein a drop in the annulus pressure above the packer may be as the result of one or more factors, such as: damage to the casing or tubing above the shut off means; damage to a flow line; undue movement of the ice platformor the like relative to the casing; an excessive increase or abnormal drop in well pressure; manipulation of a manual valve; and/ or others.

A further object in accordance With the foregoing objectives is to provide an apparatus wherein the tubing is suspended in the casing as by means of a hook-wall packer and anchor mechanism or other suitable supporting means, and wherein the casing head has a slip fit with the tubing, whereby if the platform should be severely damaged or caused to shift relative to the well, the well head equipment may be stripped off of the tubing, thus to automatically effect operation of the shutoff valve, without disturbing the casing.

Another object is to provide an apparatus wherein a trip line is disposed about the platform in proximity to the surface of the water so as to be initially contacted by a tide or storm driven object which might tend to damage the platform, this trip line being connected to a valve for venting to the atmosphere the fluid pressure necessary to enable continued ilow of production fluid through the tubing, thus automatically shutting off the ow upon engagement by a tide or wind driven object or the like.

Still another object is to provide a well shut-off, an apparatus wherein a full opening valve is disposed in the tubing at a point a substantial distance down the tubing from the well head, the valve being fluid pressure operated so as to be held open by uid pressure in the annulus, whereby certain wire line operations such as perforating of the downhole casing and formation or other operations requiring the passage of a fairly large tool down the tubing, may be performed through the valve assembly.

Other objects and advantages will be hereinafter described or will become apparent to those skilled in the art, and the novel features of the invention will be defined in the appended claims.

In the accompanying drawings:

FIG. l is a diagrammatic view showing well head equipment in accordance with the invention, and showing casing and tubing strings together with the novel valve assembly hereof which is operably responsive to certain conditions at the well head;

FIG. 2 is an enlarged fragmentary detail View showing the casing head assembly in section, and showing certain associated liuid conduits communicating with the annulus;

FIG. 3 is a diagrammatic View showing a well platform equipped with a trip line in accordance with the invention;

FIG. 4 is an enlarged detail view in vertical section, with certain of the parts shown in elevation, of a full open gate valve in accordance with the invention;

FIG. 5 is an enlarged detail View similar to FIG. 4, but showing the valve in a closed position;

FIG. 6 is a transverse sectional view, as taken on the line 6-6 of FIG. 4;

FIG. 7 is a fragmentary view in transverse section, as taken on the line 7-7 of FIG. 4; and

FIG. 8 is a fragmentary detail view in elevation showing the valve gate mounting, this view being taken substantially on the line 8 8 of FIG. 7.

Like reference characters in the several Views of the drawings designate corresponding parts.

Referring particularly to FIGS. l and 2, Well apparatus is shown, including a casing l disposed in a well with a tubing string 2 concentrically arranged in the casing. The tubing is suspended in the casing at a point spaced substantially downwardly from the top of the casing by suitable means such as a tubing anchor (not shown). Above the anchor is a suitable packer. A hook-wall packer assembly 3 may advantageously be used, thus eliminating of ow of fluid from the i'low line F.

the need for a separate anchor in some cases. The hookwall packer need not be described in detail in that it is a known type of packer. Generally, however, `the packer assembly 3 includes a packer element 4 adapted to seal olf the annulus between the casing and the tubing. Means such as a plurality of casing wall engaging slips 5 are employed for securing the packer in place. Operatively connected tto the slips 5 is a plurality of friction pads 6 engageable with the casing to set the slips 5 and prevent relative movement of the packer assembly 3 and the tubing 2 in one direction. Depending from the packer assembly is a suitable number of hooks 7 adapted for engagement with a similar number of lugs S carried by the tubing 2, whereby relative movement of the packer assembly 3 and the tubing 2 in the other direction is precluded.

interposed in the tubing string 2 between the hookwall packer assembly 3 and the upper end of the tubing is a novel fluid pressure operated valve assembly generally designated 9 which will be more specically described as the description progresses. This valve 9 is illustrative of one form of valve suitable for use in the apparatus hereof and is more particularly the subject matter of co-pending application Ser. No. 669,012 led July 1, 1957. Other valves which are ideally suited to such use are also the subject of co-pending applications Ser. No. 669,011, led July 1, 1957, and Ser. No. 678,874, filed August 19, 1957.

In accordance with one of `the features of the invention, a safety landing sub 10 is carried by the upper end of the tubing string 2. Removably mounted on the upper end of the landing sub 19, as by a slip fit, is an annular landing ange 11 which is interposed between upper and lower sections 12 and 13, respectively, of casing head means generally designated H. At its inner periphery, the landing flange is provided with suitable seals or packing rings 11', so that the landing flange constitutes an upper barrier between the casing 1 and tubing 2 for preventing the direct flow of tiuid from the tubing into the casing. In addition, casing head section 13 is sealingly engaged at the upper extrem-ity of the casing 1 as by a threaded connection 1.

Disposed above the casing head H is a conventional Christimas tree T having ow lines F, F', each having a flow valve V and V', respectively. The Christmas tree T also comprises a valve V between the casing head H and the flow lines F, F', and a valve V" disposed above the ow lines F, F'. If desired the Christimas tree may be closed at its top by a cap C having a suitable gauge G thereon.

In accordance with the method hereof, the uid pressure operated valve assembly 9 is adapted to be maintained open, that is, in a condition enabling the well to ow or produce through the tubing 2, responsive to uid pressure .in the annulus 14 between the casing 1 and the tubing 2. Such fluid pressure may be derived from a number of sources in the performance of the instant method.

For example, in FIG. 1, fluid communication is established between the flow lines F, F and the annulus 14. In this connection, a line 15 is tapped into the flow line F. This line 15 is joined with a line 16 which is connected with the landing flange 11, the landing flange having a passage 17 leading to the annulus 14. 1n addition, the line 16 is extended as at 16 for connection to a pump or other source of pressure fluid (not shown), and

Vva vent line 18 is also connected to the line 16. Each of thelines 15, 16' and 13 is provided with a control valve, respectively designated 19, 2i) and 21.

At the other side of the Christmas tree T and communicating with the ow line 1FY is a pressure line 22 having an orifice union 23 therein for limiting the rate The line 22 is connected with a line 24 which establishes uid communi- 4 cation with the annulus 14 through a passage 25 in the landing ilange 11.

The line 24 has a manual valve 26 and a multiway valve Z7 therein. The multiway valve 27 is adapted to selectively establish communication between the line 24 and a vent 28 and between the line 24 and an extension 24 of the latter, the flow from line 24 to the extension 24 being interrupted by the valve 27 upon venting of the line 24. Valve 27 may be of any desired construction but is preferably operable by a lever 27 for a purpose which will be hereinafter more fully described.

Also, connected to iiow line F is a pair of pilot valves 29 and 30, a manual valve preferably being interposed between each pilot valve 29 and 30 as at 31 and 32, respectively, and the line F'. A cross line 33 establishes communication between line 24 and the pilot valves 39 and 30, and each of said pilot valves is provided with a vent 34 and 35, respectively. The details of the pilot valves are not germane, and they may be of any desired construction, whereby one of the pilot Valves, say pilot valve 29, is responsive to `a drop in pressure in the line F below a predetermined value to vent line 24 to the atmosphere through vent 34, whereas lthe other pilot valve 30 is responsive to pressure in line F above a predetermined value to vent line 24 through vent 35.

As has been previously stated, the valve assembly 9 is adapted to be maintained open responsive to uid pressure in the annulus 14. Accordingly, the valve assembly 9 has a cylindrical housing 36 having a suitable number of ports 37 leading from the annulus 14 into the housing 36.

Referring particularly to FIGS. 4 and 5, it will be seen that the housing 36 preferably includes a lower section 38 constituting a pressure cylinder and threadedly connected as at 39 with a coupling 40 adapted to be connected with the depending tubing string, shown in FIG. 1. An upper housing section 41 is threaded to the lower section 38 as at 42 and at its upper end the housing 41 is threaded to a coupling 43 adapted -to be connected to the tubing string above the valve 9. Suitable sealing means are employed for preventing the passage of fluid between the couplings 40 and 43 and the ends of the housing sections 33 and 49, respectively, such as 0-ring or other sealing elements 44 and 4S. Another sealing element or O-ring 46 is interposed between the threaded ends of the housing sections at the connection 42 thereof.

At a point spaced below the lower extremity of the upper coupling 43, the upper housing section is provided with an annular shoulder 47 projecting radially inwardly. A valve seat 48 having a radial flange 49 is supported on the shoulder 47, with the flange 49 clamped between the shoulder 47 and the lower extremity of the coupling 43. Preferably, an O-ring 50 or other sealing means is interposed between the inner periphery of the housing section 41 and the flange 49 to prevent flow of well uid around the seat. The seat 4S has a tapered or lbeveled face adapted to be engaged by an annular complementally tapered or beveled gate valve 51.

Gate valve 51 comprises a disc like 4base 52 on which is secured an annular valve washer or rubber 53. The washer or rubber 53 is secured in place by a circular disc 54 having a marginal ange 55 overlying the washer 53, this disc S4 having a threaded stem S6 which projects through a central opening in the base 52 into threaded engagement with a cross member 57. At its opposite ends, the cross member 57 is bifurcated as at 58 and 59, and the cross member is pivotally supported on an ear 69 depending from one side of the valve seat 48 and disposed in the bifurcated end 58 of the cross member 57, a pivot pin 61 extending through the interengaged ear and bifurcations.

At its other end, the cross member 57 is pivotally connected by a pin 62 with an end of a longitudinally extended link 63, said link being connected at its other end t0 fluid pressure operated means for shifting the link in opposite directions so as to close and open the Valve.

Such fluid pressure operated means comprises a sleeve 64 reciprocably disposed in the lower housing section 38 and projecting upwardly into the upper housing section 4I. iIt will be observed that housing section 38 projects radially inwardly to provide a shoulder 65 and an annular space 66 is defined between the sleeve 64 and the housing section 38, into which space liuid may flow from the annulus 14 through the ports 37. At its lower end the sleeve 64 is formed with a radially projecting flange y67 constituting a piston. Sealing means, such as an O-ring 68 and an 0- ring 69, are respectively interposed between the upper end of sleeve 64 and the inner periphery of the housing section 38 and between the piston 67 and said housing section 78, so that uid admitted to the space 66 cannot escape therefrom. A coiled compression spring 70 is interposed between the shoulder 65 and the piston 67 so as to normally bias the sleeve 64 to the position shown in FIG. 4. At its lower extremity the sleeve 64 is provided with a bevelled surface 64 which is responsive to the flow therethrough of production iluid to effect upward movement of sleeve 64.

Means are provided for interconnecting the link 63 previously referred to with the sleeve 64. Such means preferably comprises a collar '71 disposed about the sleeve 64 and fixed thereon as by pins or keys 72. As is best seen in FIG. 6, the collar 71 is bored eccentrically so as to provide a massive link supporting portion at one side thereof having upstanding ears 73, between which the lower end of lthe valve operating link 63 is connected aS by means of a pivot pin 74. The upper end of the sleeve 64 is axially slotted as at '75, so that upon upward movement of the sleeve 64 the link 63 is free to span the sleeve through the slot 75 and assume the position shown in FIG. 5, 4thus closing the valve.

As is 4best seen in FIGS. 4 and 5, the inner diameter of the upper valve housing section 41 is substantially greater than the minimum inside diameter of the couplings 40 and 43. Accordingly, when the valve 51 is full open, as shown in FIGS. 4 and 7, it is effectively recessed in the housing section `41 and maximum iluid flow through the valve assembly is permitted, limited only 'by the inside diameter of the coupling 40 and 43.

A further advantage in this structure is the fact that wire line tools (not shown) of any desired type may be run into the Well on a wire line. 'I'he valve assembly 9 offers no obstruction to Ithe passage of such wire line tools as may be employed in perforating, fracturing, cementing, or testing operations. Instead, as an extremely advantageous feature of the present construction and method, the annulus 14 may be pressurized to open the valve, as will hereinafter more fully appear, during such wire line operations.

As has been previously described, the multi-way valve 27 in line 24 has a lever 27 for effecting operation of the valve. Since an important feature of the present invention is the step of and means for automatically shutting off well ilow if the platform or well head equipment should be subjected to a damaging impact, such as for instance `from tide or wind driven objects, in the case of an offshore well, the lever 27 has an end of a safety cable Sti connected to its free end (see FIG. l). The platform P is diagrammatically illustrated in FIG. 3, and as shown in this view, the cable 8u is threaded through a series of eyes S1 disposed in spaced relation about the platform P so as to provide a perimetrical trip line, the line being secured at its other end to a dead end anchor 82. By virtue of this arrangement an object, upon striking the line 30 about the platform P, will effect operation of the valve 27, thus shutting off ilow of the well in a manner which will appear hereinafter.

The structure heretofore described, will automatically shut off flow from the well or if desired such flow may 6 be interrupted manually, and a number of Safety shut olfs are provided.

In this connection, assuming that the well is in condition for production but requires swabbing, the valves 19 and 2l in line 15 may be closed and valve 26 in line Effi may be opened, while sweet oil or the like is pumped into the annulus I14 through lines 16 and 16, so as to fill the annulus 14 and the annular space 66 in the valve assembly 9. When these spaces are llled with sweet oil or the like, such oil will commence to flow through valve Z6 which may then be closed. Continued operation of the sweet oil pumping means (not shown) will build up pressure in the annulus so as to cause the transmission of such fluid pressure through the ports 37 in the lower valve housing section 38, into the annular space 66 behind the piston y67 on sleeve 64. Such fluid pressure will assist the spring 76 in maintaining the valve open as shown in FIG. 4. Under such circumstances the valve assembly is full open and a swab (not shown) may be run down on a line to the producing Zone. The well may then be swabbed into production flow.

When the well is owing, the valve V will be closed olf, while production fluids pass through either or both of the iiow lines F `and F through ilow valves V and V. Assuming that flow is passing through both of lines F and F', valve 20 in line 16 will be closed off, as will be vent valve 2d and vent 28 through multi-way valve 27, but valves 19, 26, 31 and 32 will be open. Accordingly, pressure from the production uid will be imposed on the sweet oil in the annulus 14 and in annular space 66 in the valve assembly 9.

As long as the well is producing normally under predetermined pressure, vents 34 and 35 of under and over pressure pilot valves 29 and 34.) will remain closed. However, should production pressure exceed or fall below the pressure which the pilot valves are pre-set for, ow between line 24 and flow line F will automatically be vented to the atmosphere. This will relieve iuid pressure in the annulus 14 and annular valve space 66, whereupon the further liow of production fluid will act upon the lower end surface 64 of sleeve 64, thus shifting the sleeve 64 to the position of FIG. 5, to close the valve gate 51 on the seat 4S. It will be noted in FIG. 5, that the sleeve y64 extends upwardly into engagement with the gate 51 when the latter is closed so as to aid in preventing leakage past the valve. Accordingly, the well is `automatically shut in upon excessive or unduly diminished llow pressures.

The same result may be accomplished by opening vent valve 2l, which will relieve the fluid in the annulus 14 from production pressure. Thus, manual llow control is effected.

Of course, in the event that the casing head H, which has a slip fit with the casing and tubing should be inadvertently knocked off as by reason of a collision of some object with the platform or with the well head equipment, or in the absence of an over pressure pilot valve such as that indicated at 3d, should be blown off, the pressure in the annulus will also be reduced. Thereupon, the valve 9 will function as a subsurface blow-out preventer.

However, in use of the invention, on an offshore rig, particularly, the trip line 80 will be pulled upon contact by an object which might do ydamage to the platform P upon collision. The trip line S0 will serve to vent line 24 to atmosphere at a faster rate than pressure can be supplied through orifice union 23, thus causing a drop in annulus pressure which will allow production ilud pressure operation of the valve assembly 9 in the previously described manner.

It will now be apparent, that, in accordance with the objectives stated 'at the commencement hereof, the invention provi-des a method of shutting olf well ilow which comprises, broadly, the steps of installing in a production tubing string a fluid pressure responsive valve adapted to be closed by production fluid pressure, said valve communicating with the annulus between the tubing and well casing above a packer; pressurizing the annulus above the packer-to open theV valve, and depressurizing the annulus responsivefto one or more of a number of different occurrences at the well head, so as to close the valve and prevent further ilow. These occurrences at the well head, as has been previously mentioned, may be purely manual, as in the case of opening vent valve Z1, or on the other hand, such occurrences may be blowing off of the well head, opening of over or under pressure vents, opening of a vent responsive to collision, or the like.

Other means for depressurizing the annulus 14, and other situations under which closure of the valve may be desirable will be apparent to those skilled in the art, but changesiand alterations may be resorted to without departing from the spirit of the invention as delined in the Aappended claims.

the well; a packer between said tubing and the casing; a

fluidpressure operated valve in said tubing above the packer; means for directing iluid under pressure into the space between the casing and the tubing above said packer; said valve having actuator means extending longitudinally of and coaxial with said tubing and having opposed areas responsive to uid pressure, said actuator means communicating with said space to subject one of said areas to the pressure of fluid in said space for opening the valve upon the application of pressure to the fluid in said space and lfor closingthe valve upon reduction of fluid pressure in said space; said actuator means having a fluid passage therethrough aligned with said production tubing and substantially as large as the inside diameter of said tubing.

2. Well ow control equipment for shutting off the iiow Vofliuid from a well having a casing therein, comprising:

a casing head; a flow line leading from said casing head; 'production tubing extending from said casing head into the well; a packer between said tubing and the casing; a "uid pressure operated valve in said tubing above the packer; means defining a barrier between the casing and tubing above said valve for preventing the flow of fluid from said tubing into the casing; means for directing fluid under pressure into the space between the casing and the tubing above said packer; said valve having actuator means communicating with said space for opening the valve upon the application of pressure to the huid in said space and for closing the valve upon reduction of iluid pressure in said space; said actuator means having a fluid passage therethrough aligned with said tubing and substantially as large as the inside diameter of said tubing.

3. Well flow control equipment for shutting oit the ow of uid from a well having a casing therein, comprising: a casing head; a flow line leading from said casing head; production tubing extending from said casing head into the well; a packer between said tubing and the casing; a fluid pressure operated valve in said tubing above the packer; means for directing uid under pressure into the space between the casing and the tubing above said packer; said valve having actuator means communicating with said'space for opening the valve upon the application of pressure to the uid in said space and for closing the valveupon reduction of fluid pressure in said space; and `means for eiecting a reduction in the fluid pressure in said space; said actuator means having a iluid passage therethrough aligned with said tubing and substantially as 4large as the inside diameter of said tubing.

4. Well ow control equipment for shutting ott the ow of uid fromV a well having a casing therein, comprising: arcasing head; a flow line leading from said casing head;

production tubing extending from said casing head into the well; a packer between said tubing and the casing;

a Huid pressure operated valve in'said tubing above the packer; means for directing fiuid=under pressure into the space between the casing and thetubing above said packer; said valve having actuator means communicating with said space for opening the valve upon the application of pressure to the iluid in said space and for closing the valve upon reduction of uid pressure in said space; said casing head having means providing a slip fit with said tubing, whereby the casing head means may be removed without disturbing said tubing; and means suspending said tubing in said casing at a point spaced downwardly from said casing head.

5. Well flow control equipment for shutting off the ow of fluid from a well having a casing therein, comprising: a casing head; a ow line leading from said casing head; production tubing extending from said casing head into the well; a packer between said tubing and the casing; a tluid pressure operated valve in said tubing above the packer; means for directing huid under pressure into the space between the casing and the tubing above said packer; said valve having actuator means communicating -with said space for opening the valve upon the application of pressure to the huid in said space and for closing the valve upon reduction of lluid pressure in said space; said fluid directing means including a conduit leading from said flow line and communicating with said space through the casing head; a vent communicating with said conduit for venting the latter to 4the atmosphere; and valve means for opening and closing said vent.

6. Well flow control equipment for shutting ot the flow of fluid from a well having a casing therein, comprising: a casing head; a ilow line leading from said casing head; production tubing extending from said casing head into the well; a packer between said ltubing and the casing; a iluid pressure operated valve in said tubing above the packer; means for directing iiuid under pressure into the space between the casing and the tubing above said packer; said valve having actuator means communicating with said space for opening the valve upon the application of pressure to the uid in said space; and for closing the valve upon reduction of fluid pressure in said space; said fluid directing means including a conduit leading from said flow line and communicating with said space through the casing head; a vent communicating with said conduit for venting the latter to the atmosphere; and manually operable valve means for opening and closing said vent.

7. Well flow control equipment for shutting oif the flow of uid from a well having casing therein, comprising: a casing head; a flow line leading from said casing head; production tubing extending from said casing head into the well; a packer between said tubing and the cas- Y ing; afluid pressure operated valve in said tubing above the packer; means for directing iluid under pressure into the space between the casing and the tubing above said packer; said valve having actuator means communicating with said space for opening the valve upon the application of pressure to the fluid in said space and for closing the valve upon reduction of uid pressure in said space; said fluid directing means including a conduit leading from said ow line and communicating with said space through the casing head; a vent communicating with said conduit for venting the later to the atmosphere; and valve means responsive to pressure in said iiow line for opening and closing said vent.

8. Well ilow control equipment for shutting olf the How of lluid from a Well having casing therein, comprising: a casing head; a tlow line leading from said casing head; production tubing extending from said casing head into the well; a packer between said tubing and the casing; a fluid pressure operated valve in said tubing above the packer; means for directing fluid under pressure into the space between the casing and the tubing above said packer; said valve having actuator means communicating with said space for opening the valve upon the application of pressure to the fluid in said space and for closing the valve sheaves upon reduction of fluid pressure in said space; said duid directing means including a conduit leading from said iiow line and communicating with said space through the casing head; a vent communicating with said conduit for venting the latter to the atmosphere; and valve means responsive to excessive pressure in said flow line for opening and closing said vent whereby said valve will be opened when said vent is open and the space between the casing and the tubing above said packer is in communication With atmosphere through said vent.

9. Well ow control equipment for shutting efr" the flow of uid from a well having casing ltherein, comprising: a casing head; a flow line leading from said casing head; production tubing extending from said casing head into the well; a packer between said tubing and the casing; a fluid pressure operated valve in said tubing above the packer; means for directing liuid under pressure into the space between the casing and the tubing above said packer; said valve having actuator means communicating with said space for opening the valve upon the application of pressure to the fluid in said space and for closing the valve upon reduction of fluid pressure in said space; said fluid directing means including a conduit leading from said flow line and communicating with said space through the casing head; a vent communicating with said conduit for venting the latter to the atmosphere; and valve means responsive to a reduction below a predetermined limit o-f pressure in said flow line for opening and closing said vent.

l0. Well How control equipment for shutting olf the ilow of fluid from a well having casing therein, comprising: a casing head; a flow line leading from said casing head; production tubing extending from said casing head into the well; a packer between said tubing and the casing; a liuid pressure operated valve in said tubing above the packer; means for directing fluid under pressure into the space between the casing and the tubing above said packer; said valve having actuator means communicating with said space for opening the valve upon the application of pressure to the fluid in said space and for closing the valve upon reduction of fluid pressure in said space; said fluid directing means including a conduit leading from said flow line and communicating with said space through the casing head; a vent communicating with said conduit for venting the latter to the atmosphere; and valve means for opening and closing said vent; said conduit having an orifice union interposed between said liow line and said vent.

1l. Well apparatus for producing offshore wells, comprising: a platform adapted to be disposed adjacent the water surface; well casing extending from said platform into the earth beneath the Water; a tubing string disposed in said casing; said casing and tubing string defining an annulus therebetween; means supporting said tubing in said casing; packer means forming a fluid barrier in said annulus; a valve disposed in said tubing above said packer means; said valve having actuator means communicating with said annulus for opening the same responsive to fluid pressure in the annulus above the packer means and for closing the same responsive to a drop in fluid pressure in the annulus below a predetermined limit; casing head means for receiving well fluid from said tubing; and means for directing fluid -under pressure to said annulus from said casing head means; said casing head means providing a slip fit with said tubing string.

l2. Well apparatus for producing offshore wells, comrising: a platform adapted to be disposed adjacent the water surface; well casing extending from said platform into the earth beneath the water; a tubing string disposed in said casing; said casing and tubing string defining an annulus therebetween; means supporting said tubing in said casing; packer means forming a fluid barrier in said annulus; a valve disposed in said tubing above said ypacker means; said valve having actuator means communicating with said annulus for opening the same responsive to fluid pressure in the annulus above the packer means and for closing the same responsive to a drop in fluid pressure in the annulus below a predetermined limit; casing head means for receiving well fluid from said tubing; rneans for directing fluid under pressure to said annulus including a flow line leading from said casing head and a conduit establishing fluid communication from said liow line to said annulus; and means for venting said conduit.

13. Well apparatus for producing offshort wells, comprising: a platform adapted to be disposed adjacent the water surface; well casing extending from said platform into the earth beneath the water; a tubing string disposed in said casing; said casing and tubing string defining an annulus therebetween; means supporting said 4tubing in said casing; packer means forming a fluid barrier in said annulus, a valve disposed in said tubing above said packer means; said valve having actuator means communicating with said annulus for opening the same responsive to fluid pressure in the annulus above the packer means and for closing the same responsive to a drop in fluid pressure in the annulus below a predetermined limit; casing head means for receiving well fluid from said tubing; means for directing duid under pressure to said annulus including a iiow line leading from said casing head and a conduit establishing uid communication from said flow line to said annulus; means for venting said conduit; said venting means including a valve; operating means for said valve; and actuator means Ifor said operating means; said actuator means including trip means disposed at the perimeter of said platform and connected with said operating means.

14. Well apparatus for producing offshore wells, cornprising: a platform adapted to be disposed adjacent the water surface; well casing extending from said platform into the earth beneath the water; a tubing string disposed in said casing; said casing and tubing string defining an annulus therebetween; means supporting said tubing in said casing; packer means forming -a iluid barrier in said annulus; a valve disposed in said tubing above Said packer means; said valve having actuator means communicating with said annulus for opening the same responsive to fluid pressure in the annulus above the packer means and for closing the same responsive to a drop in iiuid pressure in the annulus below a predetermined limit; casing head means for receiving well liuid from said tubing; means for directing fluid under pressure to said annulus including a flow line leading from said casing head and a conduit establishing fluid communication from said flow line to said annulus; means for venting said conduit; said venting means including a valve; operating means for said valve; Iand actuator means for said operating means; said actuator means including trip means disposed at the perimeter of said platform and connected with said operating means; said trip means extending substantially entirely about the perimeter of said platform.

l5. Well apparatus for producing oifshore Wells, comprising: a platform adapted to be disposed adjacent the water surface; Well casing extending from said platform into the earth beneath the water; a tubing string disposed in said casing; said casing and tubing string defining an annulus therebetween; means supporting said tubing in said casing; packer means forming a fluid barrier in said annulus; 4a valve disposed in said tubing above said packer means; said Valve having .actuator means communicating with said annulus for opening the same responsive to fluid pressure in the annulus above the packer means and for closing the same responsive to a drop in fluid pressure in the annulus below a predetermined limit; casing head means for receiving Well uid from said tubing; means for directing fluid under pressure to said annulus, including a flow line leading from said casing head and a conduit establishing lluid communication from said ow line to said annulus; and means for venting said conduit; said venting means including a valve and means for operating said valve.

16. Well apparatus for producing Aoishore wells, comprising: a platform adapted to be disposed adjacent the water surface; well casing extending from said platform into the earth beneath the water; a tubing string disposed in said casing; said casing and tubing string defining an annulus therebetween; means supporting said tubing in said casing; packer means forming a fluid barrier in said annulus; a valve disposed in said tubing above said packer means; said valve having actuator means communicating with said annulus for opening the same responsive to uid pressure in the annulus above the packer means and for closing the same responsive to a drop in fluid pressure in the annulus below a predetermined limit; casing head means for receiving well uid from said tubing; means for directing uid under pres- 12 Isure to said annulus, including a flow line leading from said casing head and a conduit establishing fluid corn- Inunication from said ow line to said annulus; and means for venting said conduit; said conduit having an orifice union between said ow line and said venting means.

References Cited in the tile of this patent UNITED STATES PATENTS 2,227,538 Dorton Ian. 7, 1941 2,591,087 Millican Apr. l, 1952 2,780,290 Natho Feb. 5, 1957 2,785,755 En Dean Mar. 19, 1957 2,786,535 Boer et al. Mar. 26, 1957 2,812,822 OReilly Nov. l2, 1957

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