Swivel Control Head And Method Of Control

Abstract

A method and apparatus for providing flow control at a wellhead, characterized by the integration of a remotely operated control valve with a swivel assembly. The mode of operation and structure of the control valve are such as to enable the valve to be opened in response to the imposition of a biasing force and enable a valve to be maintained open in response to the imposition of a relatively lower biasing force. The valve may be opened and closed in response to the operation of a remote control mechanism or alternately may be opened and/or closed in response to the application of pump pressure to a conduit communicating with an interior passage of the swivel assembly.

Description

GENERAL BACKGROUND OF THE INVENTION

This invention relates to a wellhead safety device and a method of control, and more particularly to a remote control swivel control unit having a safety valve.

In connection with many well operations a swivel unit is supported at a wellhead so as to permit fluid flow between the interior of a well and a surface facility.

Conventionally, such a swivel arrangement provides a body which is connected by way of conduit means to a surface facility. A conduit string, rotatably supported relative to the body of the swivel unit, extends into the well conduit means or casing. The interior of the swivel unit provides fluid communication between the interior of the conduit string and the conduit means extending from the swivel body to the surface facility.

During many well operations it becomes highly desirable to be able to control the flow of fluid either into or out of the conduit string.

However, because of the relatively rotatable nature of the swivel components, and the rotatable and longitudinally movable nature of the conduit string, substantial complications are presented with respect to the provision of an accessible, reliable, control mechanism.

The control over flow through a conduit string, where a swivel assembly is employed, often becomes significant in connection with well testing operations.

In many well testing operations, a "testing string" is rotatably supported relative to the body of a swivel assembly which is located at the wellhead.

In conducting testing operations with an assembly of this nature the passage through the swivel assembly is opened to permit well fluid to flow upwardly from a formation, through the conduit or testing string, and then through the various communicating passage means of the swivel assembly to a surface facility which receives the formation fluid during the testing operations.

In the event that noxious or excessively high pressure fluids should pass upwardly through the conduit string during such a testing operation it may be highly desirable to be able to safely and reliably terminate such a flow of well fluids, especially when uncontrollable, and prevent such well fluids from passing through the swivel assembly and to the surface facility.

A variety of proposals have been set forth in the past in connection with the control over the flow of fluid during such testing operations. Both manual and remotely operable control valve concepts have been proposed.

However, such concepts have often been characterized by a degree of inaccessibility of operating components or by a degree of structural and operational complexity.

Accordingly, where conduit strings associated with swivel assemblies have been involved, a need has persisted for an improved control mechanism which would be reliable and accessible, not involve excessive structural and/or operational complexity, not complicate normal operations, and not provide structural encumbrances in the working area of a wellhead.

In particular, during the testing of oil and gas wells, a dangerous condition sometimes develops at the wellhead as a result of the presence of high pressure hydrogen sulfide gas. Natural gas, which is produced in both oil and gas wells, sometimes contains hydrogen sulfide. When the hydrogen sulfide laden natural gas, or sour gas as it is sometimes known, reaches the wellhead, a dangerous condition may be created if for some reason the gas is allowed to escape. This is so not only because of the high pressure involved, but also because hydrogen sulfide is a highly flammable gas which can deaden the sense of smell and which is dangerously poisonous.

It thus may become necessary, in order to protect property and insure the safety of working personnel, to devise means for cutting off the well flow when the presence of the hydrogen sulfide gas is detected.

In particular, it would be desirable to provide a remote control valve to cut off the well flow when the hydrogen sulfide gas is detected.

OBJECTS AND SUMMARY OF THE INVENTION

The present invention involves the provisions of a remote control safety valve, embodied as part of a swivel unit. This safety valve rapidly and reliably responds, when actuated, and the overall unit allows rotation of a conduit string extending from the swivel control unit and into the well.

It is a particular object of the invention to provide a swivel control unit for a wellhead including a safety valve in which the safety valve is controlled from a point remote from the wellhead.

A further object of the invention is to provide a valve mechanism, as heretofore noted, which may be opened in response to the generation of pump pressure at the wellhead so as to permit the valve to be forced to an open position and enable fluid to pass through the swivel assembly, or a conduit means, and into another portion of a well conduit string.

Another object of the invention is to provide a valve mechanism of the type heretofore noted which may be opened in response to the imposition of relatively low pressure actuating fluid and be held open by the continued application of even lower pressure actuating fluid.

It is another object of the invention to provide a swivel control unit for a wellhead including a safety valve in which the well fluid is utilized to tend to pressure balance the valve in an open position.

It is still another object of the invention to provide a swivel control unit for a wellhead including a safety valve in which an actuating fluid is utilized to open the safety valve and position the safety valve so that it may be pressure balanced by the well fluid.

It is a related object of the invention to provide a method of controlling the flow of well fluid from a wellhead from a remote area.

It is another related object of the invention to provide a method of balancing a valve at a wellhead in an open position, utilizing the well fluid and an externally applied acutating fluid.

In accomplishing at least some of the foregoing objectives, there is presented through this invention a method of performing well operations wherein swivel means is connected with a well conduit string. The swivel means is supported above well conduit means. This arrangement permits the conduit string to undergo longitudinal as well as rotary movement relative to the well conduit means.

A passage means is provided in the swivel means which extends generally longitudinally of the swivel means and is disposed in fluid communication with the interior of the conduit string. Body means of the swivel means is arranged at the wellhead so as to permit rotation of the conduit string. Branch conduit means in the body means is operable to communicate with the longitudinally extending passage means of the swivel means.

A valve means carried by the swivel means is operable to control fluid flow between at least a portion of the longitudinally extending passage means and at least a portion of the branch passage means. This valve means is maintained operable to control flow between the general longitudinally extending passage means and the branch passage means while the conduit string is stationary relative to well conduit means and while the conduit string is undergoing rotational movement relative to the well conduit means.

An independently significant method aspect of the invention, in the context of the foregoing basic method, entails the remote actuation of the valve means. In this additional method aspect of the invention, a valve biasing means is operable in response to the opening of the valve means to cause the pressure of fluid in the longitudinally extending passage means of the swivel means to exert a valve opening biasing force on the valve means, so long as the valve means remains in an open position. Additionally, a valve isolating means remains operable to substantially prevent the pressure of fluid in the generally longitudinally extending passage means from exerting a valve opening biasing force on the valve means when the valve means is disposed in a closed position.

A third, independently significant method aspect of the invention involves the utilization of a pressure responsive surface means which is operable in response to an increase of pressure in the branch conduit means to exert a valve opening force on the valve means.

Other independently significant facets of the invention relate to the aforesaid valve mechanism itself and its mode of operation and to synergistically interacting combinations of apparatus elements or means which cooperate to perform the method steps heretofore set forth.

A preferred embodiment of the invention, intended to accomplish at least some of the foregoing objects, includes a swivel control unit engaged with a conduit string extending up from a well casing. The swivel control unit utilizes both the pressure of the well fluid and the pressure of an externally applied actuating fluid to control the actuation of a valve contained therein.

The swivel control unit includes a generally cylindrical swivel body which may be generally secured against rotation and a generally tubular body or mandrel threadedly engaged with the conduit string and extending through and disposed in coaxial relationship with the swivel body. The tubular body or mandrel is rotatable along with the conduit string, relative to the swivel body. This relative rotation, as well as the axial movement of the control unit and conduit string assembly, permits the setting and releasing and actuation of downhole test tools. Thus, there is assured a control unit which will permit controlled flow from the well, if desired, while downhole testing tools are being manipulated.

The rotatable, generally tubular body includes: a central bore aligned with the central bore through the conduit string, and through which well fluid is conveyed to the wellhead; discharge port means through which the well fluid is removed outwardly from the tubular body; and pressure port means through which a portion of the well fluid is directed for communicating the pressure of the fluid in the central bore to one end of a valve so as to bias the valve to a closed position.

Between the mandrel and swivel body is an annular, axially extending chamber. This chamber communicates with an exit port means in the swivel body as well as with the discharge port means and the pressure port means.

Supportably received within the chamber are the valve and a spring. This spring exerts a pressure tending to bias the valve toward a closed position. In the closed position, the valve is adapted to interrupt the flow of well fluid from the discharge port means through the chamber, to the exit port means.

The valve is retained in its closed position by the spring and by the fluid pressure in the central bore communicated through the pressure port means and acting against one end of the valve. To open the valve, actuating fluid is delivered through an inlet port in the swivel body, from a remote source, into a chamber portion communicating with another end of the valve. The actuating fluid exerts a pressure against this other end of the valve, acting in a direction opposite to the aforesaid communicated pressure of the well fluid and the spring pressure.

Upon application of the actuating fluid pressure the valve will open and establish a flow of well fluid from the discharge port means, through a portion of the chamber, and out the exit port means. This flow gives rise to a discharge pressure which is exerted on the same end of the valve as that upon which the actuating fluid pressure is exerted.

The pressures exerted by the well fluid on the different ends of the open valve are such that the open valve tends to become pressure balanced. Thus, the pressure of the actuating fluid may be reduced, when the valve is open, to a value sufficient to overcome only the spring pressure. If, for any reason, the actuating fluid pressure is reduced or removed, or the pressure balance condition is disturbed, the valve will tend to close.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the present invention will become apparent from the subsequent detailed description thereof in connection with the accompanying drawings in which:

FIG. 1 schematically illustrates the swivel control unit of the present invention suspended from a travelling block and connected to a conduit string;

FIG. 2 is a vertical cross-sectional view illustrating structural details of the swivel control unit of the present invention;

FIG. 3 is an enlarged, fragmentary, vertical cross-sectional view illustrating the inlet port of the swivel body, shown in FIG. 1, through which actuating fluid is delivered to the second annular axially extending variable volume chamber portion;

FIG. 4 provides a somewhat further enlarged view of a portion of FIG. 2 illustrating the valve in its closed position; and

FIG. 5 provides another somewhat further enlarged view of a portion of FIG. 2, illustrating the valve in its open position, while under the influence of full actuating fluid pressure.

DESCRIPTION OF THE PREFERRED EMBODIMENT

In describing a preferred embodiment of the invention reference will be made to a swivel assembly intended to be associated with and support a well testing string.

Exemplary of well testing strings with which such an assembly may be incorporated are testing strings or well tool assemblies featured on pages 140-160 of the Halliburton Sales and Service Catalog (1968), available from Halliburton Services, Duncan, Okla.

In arrangements of this nature, the swivel assembly mandrel and/or the testing string would be supported by wellhead support means while the swivel assembly body would be connected with stationary well fluid receiving means located at or near the wellhead.

The general purpose of this arrangement is to provide manipulative control over the testing string, while also providing control over the flow of formation fluid upwardly through the testing string and through the swivel assembly to the well fluid receiving means.

While the invention will be described in this general context, it will be recognized that its utility is of a broader nature and that the concepts may be employed, for example, during operations where fluid is being injected into a well.

Overall Structure

Referring now more particularly to the drawings in which like numerals are used to indicate like parts throughout the various views thereof, FIG. 1 schematically illustrates the swivel control unit 2 in a wellhead installation.

At its lower end, the swivel unit 2 is threadedly connected to a well conduit or testing string 8, either directly or through an adaptor 10. The adaptor 10 may include a manual plug valve 12.

Extending outwardly from a generally cylindrical swivel body 16 of the control unit 2 is an actuating fluid conduit 14. The conduit 14 is indicated as extending to a remote control source (not shown), from which opening and closing of a safety valve 82 is controlled, in a manner to be described hereinafter.

As shown in FIGS. 1 and 2, a swivel mandrel 18, journalled within swivel body 16, is connected at its lower end with conduit string 8 via valve assembly 12 and adaptor 10. The upper end of mandrel 18 is connected with a threaded adaptor 64.

Adaptor 64 may, in turn, be threadably connected with a handling or support head 4 as generally and schematically shown in FIG. 1. This support head 4 may include a portion 6 which would be supported by conventional elevators associated with wellhead hoisting and lowering gear.

Exemplary of a support head which might be employed is a rig elevator supported, bail assembly normally used to support an L-T 20 control head, available from Halliburton Services, Duncan, Okla. A swivel and handling subassembly shown on page 63 of the 1968 Halliburton Sales and Service Catalog and available from Halliburton Services, Duncan, Okla., might also be employed for this purpose.

With the general swivel arrangement heretofore described, the entire axial load of the testing string 8 is carried by the support head means 4 and mandrel 18. In this manner, the axial weight of the testing string 8 is not transmitted to the swivel body means 16 or its associated bearing means. Thus, the swivel means 2 will permit rotary movement of the swivel mandrel 18 and test string 8 relative to the swivel body 16, regardless of the axial load or weight imposed on swivel mandrel 18.

Swivel Structure

Referring now to FIGS. 2-5, the swivel control unit 2 is shown to include the generally cylindrical swivel body 16, a generally tubular body or mandrel 18, and the adaptor 10. The generally tubular body 18 extends through, is journalled within, and is coaxial with the generally cylindrical body 16.

Relative rotation of the swivel body 16 and the tubular mandrel 18 is achieved by the rotation of the conduit string 8 which rotates the tubular mandrel 18. During this rotation, the swivel body 16 is held relatively stationary by virtue of its connection to conduit means extending to a stationary, well fluid receiving site, not shown.

The swivel body 16 includes: an upper section 20 from which a pair of bosses 22 and 24 radially extend; a cylindrical skirt 26, which extends axially from the upper section 20; and a swivel nut 28, which is engageable with the open end of the skirt 26.

The boss 24 includes an internally threaded socket 36 into which a nipple 38 is threadedly engaged. This nipple connects to conduit means leading to the well fluid receiving means. The nipple 38 has a bore 42 which is coaxial with an exit port 44 of the swivel body 16.

Outlet conduit or nipple 38 may be connected with a manifold control head assembly, not shown. This assembly may comprise components peripherally encircling swivel body means 16, with the control head assembly being connected through conduit means to the stationary well fluid receiving means in the vicinity of the wellhead. A control head which may be employed for this purpose comprises an L-T 20 control head described on page 143 of the 1968 Halliburton Sales and Service Catalog, available from Halliburton Services, Duncan, Okla. The support of this control head may be facilitated by a control head supporting socket 30 formed in boss 22.

In this arrangement, the conduit connection between the well fluid receiving site and conduit means 38, or its associated control head, will tend to prevent rotation of swivel body 16 and its associated components even though the conduit string 8 and swivel mandrel 18 are being rotated to effect certain operational manipulations of the testing string 8.

Such rotational mnaipulations may be effected, for example, by drivingly engaging a portion of the conduit string 8 with a rotary table at the wellhead, possibly providing vertical support for the conduit string with rotary table slips, and operating the rotary table to effect rotation of the conduit string 8.

Alternatively, full or partial vertical support may be provided by the adaptor 4 and elevators, with rotation being imparted to the conduit string 8 by manual manipulation of tongs or wrenches. In some instances, rotation of string 8 may be effected with all of the weight of the testing string being supported within the well casing.

The skirt 26 includes, in addition to a threaded portion at its open lower end for receiving in threaded engagement therewith the swivel nut 28, four indicator slots 29 through which the position of the valve 82 can be observed, as described hereinafter.

The tubular body 18 defines a central bore 46 through which a well fluid flows.

As the tubular body 18 emerges from the lower end of the swivel body 16, it flares out to form a shoulder 48 and a skirt section 50 extending therefrom. The shoulder 48 seats a thrust bearing 52 and an annular sealing ring 54. The bearing 52 fits within a cavity 56 defined by the tubular body 18 and shoulder 48 along with the swivel nut 28. The sealing ring 54 is provided to confine bearing lubricant within the cavity 56.

The skirt 50 receives therein an adaptor 10 in threaded engagement therewith. The adaptor 10 has a skirt section 58 which is internally threaded for receiving the conduit string 8 in threaded engagement therewith. The adaptor 10 defines a central bore 60 therethrough which is coaxial with the central bore 46 of the tubular body 18. The central bore 60 forms a continuation of the central bore 46 for the flow therethrough of the well fluid.

The adaptor 10 also includes a plug valve 12 which can be actuated by the rotation of handle 62. The valve 12 provides, therefore, a means for manually controlling the flow of well fluid through the central bore 60 and into the central bore 46. Desirably, valve 12 may comprise a LOTORC plug valve available form Halliburton Services, Duncan, Okla., and described on pages 68-69 of the 1968 Halliburton Sales and Service Catalog.

A plug 66 is threadedly engaged within the top part of the tubular body 18. This plug 66 prevents outward axial flow of the well fluid from the central bore 46.

The top part of the tubular body 18 may also threadedly engage the flange portion 70 of a tubular wear sleeve 68. The tubular sleeve 68, if used, extends through the swivel body 16 to a shoulder 72 which borders the cavity 56. The tubular sleeve 68 and the boss section 20 define an annular cavity 74 within which a thrust bearing 76 is located. An annular sealing ring 78 is provided to confine the bearing lubricant within the cavity 74.

Safety Valve

The swivel body 16 and the mandrel 18 define therebetween an annular axially extending chamber 80. Within the chamber 80 a valve 82, a compression type coil spring 84 and a valve positioning sleeve 86 are located. Both the positioning sleeve 86 and the spring 84 rest against a surface 88 of the swivel nut 28. The upper end of sleeve 86 provides a stop operable to engage valve 82, when it moves down, and determines the open valve position.

The valve 82 comprises a piston including an annular head portion 90 and two annular axially extending sleeve portions 92 and 94, directed oppositely away from the head portion 90.

The annular axially extending chamber 80 provides three annular, axially extending, variable volume chamber portions.

The first chamber portion 96 is defined by the positioning sleeve 86, the head portion 90, the axially extending sleeve portion 92 and the tubular sleeve 68. The second chamber portion 98 is defined by the head portion 90, the axially extending sleeve portion 94 and the swivel body 16. The third chamber portion 100 is defined by the axially extending sleeve portion 94, the tubular sleeve 68 and the swivel body 16.

The tubular body 18 is provided with one or a plurality of equally spaced pressure ports 102 and one or a plurality of equally spaced discharge ports 104. The tubular sleeve 68 is provided with openings 106 and 108 which are radially aligned with the pressure ports 102 and the discharge ports 104, respectively.

In order to ensure that the openings 106 of the wear bushing remain aligned with the mandrel openings 102, pin means 110, shown in FIG. 2, may intersect certain of the aligned openings 102 and 106 of the sleeve 68 and the body of mandrel 18 so as to maintain the ports or openings 102 and 106 in radial alignment.

As will be recognized, sleeve 68, in essence, comprises a wear bushing and thus may be considered as a mere external portion of mandrel 18. Thus, a mandrel wear surface may be provided by means other than the separate wear sleeve 68. For example, aceramic coating on the exterior of the mandrel 18 might be employed.

The third chamber portion 100 establishes a passage between the discharge ports 104 and the exit port 44 through which the well fluid flows when the valve 82 is open.

The actuating fluid which, for example, may be nitrogen, is directed from a remote source in the vicinity of the wellhead through the conduit 14. This conduit is threadably engageable with an inlet port 112 of the swivel body 16. Port 112 communicates with an annular chamber 114. The annular chamber 114 leads the actuating fluid into a second chamber portion 98, to thereby enable the fluid to exert pressure against the upper side of the head portion 90.

Mode of Operation

The mode of operation will be described with reference to FIGS. 3-5.

With the valve 82 closed (FIGS. 3 and 4), and well fluid present in central bore 46, the first chamber portion 96 fills with well fluid which is bled from the central bore 46 through the pressure ports 102 and the aligned holes 106. Thus, the pressure of the fluid in the central bore 46 is communicated to the lower side 90b of the head portion 90 of the valve 82. The pressure exerted thereby biases the valve in a closed position and augments the valve closing bias of spring means 84.

To open the valve, and thereby establish the outward flow of the well fluid from the central bore 46, an operator located at a remote source causes an acutating fluid (possibly nitrogen) to be delivered through the conduit 14, inlet port 112 and annular passage 114 into the second chamber portion 98 (FIG. 3). The actuating fluid exerts a pressure against the upper side 90a of the head portion 90 of the valve member 82.

Because of the relative dimensions of the surface areas 90a and 90b of the head portion 90 (area 90a being significantly larger) being acted upon by the communicated pressure and the actuating pressure, the actuating fluid pressure required to open valve 82 need only be a fraction of the pressure communicated from passage 46 to cavity 96. That is, the actuating pressure acting on large surface 90a need only exert a force on piston 82 sufficient to overcome the force exerted by the communicated pressure acting on small surface 90b and the spring pressure, to thereby cause the valve 82 to open and assume the position as shown approximately in FIG. 5.

With the valve 82 open, the well fluid establishes a flow through the exit ports 104 and their aligned openings 108 through the passage defined by the chamber portion 100 and out the exit port 44. During this outward flow, the well fluid fills the chamber portion 100, As a result, the pressure of the discharging fluid is exerted against surface 94a of the outwardly extending sleeve portion 94 of the valve 82.

The communicated pressure and the discharging pressure now pressure balance the valve 82 in the open position since area 94a is equal to area 95b. When the open position of the valve is achieved, which the operator can determine by looking through the indicator slots 29 to sight the relative location of the sleeve portion 92, the actuating fluid pressure may be reduced to a point sufficient only to balance the biasing force exerted by the spring 84. The result is a balanced valve held in the open position with relatively low pressure actuating fluid.

An additional operative feature of the valve arrangement is that it can be pumped open by applying a pressure through the exit port 44 into the third chamber portion 100 (FIG. 4) against the outwardly extending sleeve portion 94. When sufficient pressure is applied to area 94a, as permitted by clearance zone 100a shown in FIG. 4, to overcome the communicated pressure exerted against the lower end 90b of the piston head portion 90 in the first chamber portion 96, in addition to the spring biasing force, valve opening will occur. This will allow fluids to be forced back down the well for well "killing" operations.

Should the pressure in conduit 14 fail, the valve 82 would automatically close, due to a reduction in pressure in chamber portion 98.

It is also believed that if the conduit or control head means connected with passage 42 should rupture or break away from the swivel assembly 2, a flow of well fluid from passage 46, through the open conduit means 38 into the atmosphere, would tend to produce automatic valve closing action even if some spring force balancing, actuating fluid pressure should exist in cavity 98.

It is believed that the closing phenomena would tend to occur as a result of a reduction in pressure in well fluid in passage 42 which would result from the flow of such fluid through the pressure drop inducing orifice means as defined by exit port 104. Once such a closing of the valve means 82 occurred, the pressure balancing valve end 94 would be isolated from the pressure of fluid in passage 46 such that the valve 82 would tend to stay closed.

Overall Summary of Principal Method and Apparatus Aspects

From the foregoing discussion it will be recognized that the swivel means 2 is arranged so as to be connected with the well conduit or testing string 8 and be supported at a wellhead, above the well casing or conduit means.

The central passage means 46 of the swivel means 2 extends generally longitudinally of this swivel means and is disposed in fluid communicating relation with the interior of the conduit string 8.

The swivel body means 16 is operable to permit rotation of the conduit string 8. The branch passage means 42 of the swivel body means 16 is operable to communicate with the longitudinally extending swivel passage means 46 under the control of valve means 82.

Valve means 82 is carried by swivel means 2 and is operable to prevent fluid flow between at least a portion of the passage means 46 and at least a portion of the passage means 42. Valve means 82 remains operable to effect this flow control while the conduit string 8 is stationary relative to the well casing, as well as while the string 8 is undergoing either rotational and/or longitudinal movement relative to the well casing.

The remote actuating means provided by conduit means 14, passages 112 and 114, and chamber 98 is operable to effect selective actuation of the valve means 82 from a location remote from the swivel means 2 and the testing string 8.

The existence of this remote actuating means notwithstanding, the valve means 82 is continuously biased to a closed position by spring means 84 so as to provide a "fail-safe" mode of operation. In other words, should the pressure of actuating fluid transmitted through conduit means 14 fail, the spring 84 would ensure automatic closing of the valve means 82.

Additional manual control is provided by the manually operable plug valve means 12. This plug valve means 12 is interposed between the swivel body means 16 and the conduit string 8.

The valve sleeve portion 94, when disposed in the FIG. 5 open valve position provides a valve biasing means operable to cause the pressure of fluid in the passage means 46 to exert a valve opening biasing force on the valve means 82, tending to provide a pressure balancing phenomena acting on the open valve means. With the existence of such pressure balancing, i.e., equal pressure of fluid in passage means 46 acting on opposite axial ends of the valve means 82, the condition of valve means 82 will be determined by whether or not the pressure in actuating chamber 98 is sufficient to balance or overcome the valve closing, biasing influence of spring means 84.

While the valve means is disposed in the closed disposition illustrated in FIG. 4, the sleeve means 68 is disposed in substantially telescoping engagement with portion 94 of valve means 82 so as to function as valve isolating means, i.e., provide a seal between the extremity 94a of valve means 82 and the pressure of fluid in passage means 46. This mode of operation of the valve isolating means 68 will tend to substantially prevent the pressure of fluid in the passage means 46 from exerting a valve opening biasing force on the valve means 82, so long as the valve means 82 remains closed. As a result, the pressure of fluid in passage means 46 will augment the valve closing bias of spring means 84 so long as the valve means 82 remains closed.

Should operations require the injection of fluid into the well, for example, in order to "kill" a well, the pressure in branch conduit means 42 may be raised. This raising of pressure will exert a substantial valve opening biasing force on the pressure responsive surface means 94a carried by the valve means 82. The force acting on surface means 94a will exert a valve opening force on the valve means and cause the valve means to move to an open position.

Under these circumstances, once the valve means 82 has moved to an open position, it will tend to stabilize in an at least partially open condition so as to permit a substantially continuous injection of fluid into the conduit string 8.

The pressure balancing tendency relating to the open condition of valve means 82, acting either alone or augmented by the differential piston area phenomena resulting from the fact that the reaction surface 90a of FIG. 3 (exposed to nitrogen) exceeds the area of reaction surface 90b (exposed to pressure of fluid in passage 46), enables the valve means 82 to be maintained in an open condition with relatively low pressure nitrogen. The differential area phenomena, i.e., the fact that the area of reaction surface 90a exceeds the area of reaction surface 90b, serves to enable relatively intermediate, but still low, pressure nitrogen to effect the initial opening of the valve means 82.

Of course, once the valve means 82 is open, the nitrogen pressure may be reduced and still hold the valve means open because of the previously discussed pressure balance phenomena resulting from the exposure of each axial end of the valve means 86 to the pressure of fluid in central passage 46.

SUMMARY OF ADVANTAGES AND SCOPE OF THE INVENTION

In describing method and apparatus aspects of the invention, certain advantages have been made apparent.

A principal advantage resides in the provision of a swivel assembly including a simple but reliable control valve mechanism which may be operated from a remote location and which is possessed of fail-safe characteristics.

Another principal advantage of the invention relates to the manner in which the pressure balancing phenomena, in the open condition of the swivel valve means, enables the valve means to be maintained in an open condition with relatively low pressure actuating fluid.

Another significant advantage of the invention entails the manner in which the pressure of fluid in branch conduit means 42 may be substantially increased so as to cause the valve means 82 to open and enable fluid to be forced downwardly through the testing or conduit string.

The differential area aspects of the valve enable it to be initially opened with relatively low pressure in the actuating fluid.

Other significant advantages also result from the structure and operational characteristics heretofore noted.

The longitudinal passage 46 is characterized by a substantially unobstructed, relatively large internal diameter which enables large flow volumes to be safely and effectively handled.

The nature of this remote operating mechanism is such as to permit a variety of liquid or gaseous actuating fluids to be employed.

The load supporting swivel mandrel and the thrust bearing arrangement incorporated in the swivel mechanism enable heavy string loads to be supported and ensure easy swivel rotation, concurrent with the provision of prolonged operating life and minimum maintenance requirements.

The utilization of the remotely actuated safety valve and the manually controlled plug valve enhance the safety aspects of the tool in providing alternately operable control techniques.

The slot arrangement in the periphery of the swivel body enable an operator to determine positively the condition of the safety valve.

The overall arrangement is such as to virtually eliminate externally protruding parts which would impede operations or be vulnerable to damage.

The overall structure of the swivel assembly is such as to enable it to be safely utilized with relatively high well pressures.

The three separate pressurizing zones operable to act on the valve means provide predictable and selectively variable control criteria. The changes of volume of these zones is such as to enable the valve piston sleeve 94 to be operable to produce the pressure balancing phenomena under controlled conditions, after the inertia problems associated with intiating valve movement have been overcome.

Although the control unit is particularly useful in connection with sour gas well operations, the remote control safety valve feature makes it particularly suitable for offshore operations. In general, offshore vessels float up and down because of wave motion and in such cases the control head is normally secured high in the rig. Manual operation of the control head is hazardous under these circumstances; however, the remote control feature of the present invention would eliminate this difficulty.

When the invention is to be utilized in connection with well fluids having a hydrogen sulfide content, improved resistance to hydrogen sulfide induced embrittlement may be provided by heating treating components so as to reduce their hardness.

Although the invention has been described in connection with one preferred and illustrated embodiment, it will be appreciated by those skilled in the art that additions, modifications, substitutions and deletions not specifically described may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

What is claimed is:

1. An apparatus for use in connection with well operations, said apparatus comprising:

swivel means operable to be connected with a well conduit string and be supported above well conduit means;

passage means extending generally longitudinally of said swivel means and operable to be disposed in fluid communication with the interior of said conduit string;

body means included in said swivel means and operable to permit rotation of said conduit string relative to said body means;

branch passage means contained in said body means and operable to communicate with said generally longitudinally extending passage means;

a tubular valve sleeve carried by said swivel means and operable to prevent fluid flow between at least a portion of said generally longitudinally extending passage means and at least a portion of said brnach passage means;

said valve sleeve being operable to control flow between said generally longitudinally extending passage means and said branch passage means while said conduit string is stationary relative to said well conduit means, and while said conduit string is undergoing rotational movement relative to said well conduit means.

2. An apparatus as described in claim 1 further comprising:

resilient biasing means continuously urging said valve sleeve to a closed position;

remote actuating means operable to selectively actuate said valve sleeve in said swivel means from a location remote from said swivel means and said conduit string;

a manually operable plug valve interposed between said body means of said swivel means and said conduit string and manually operable to control flow between said conduit string and said generally longitudinally extending passage means;

valve biasing means operable in response to opening of said valve sleeve to cause the pressure of fluid in said generally longitudinally extending passage means to exert a valve opening biasing force on said valve sleeve so long as said valve sleeve remains in an open position; and

valve isolating means operable to substantially prevent the pressure of fluid in said generally longitudinally extending passage means from exerting a valve opening biasing force on said valve sleeve when said valve means sleeve is disposed in a closed position.

3. An apparatus as described in claim 2 further comprising:

pressure responsive surface means carried by said valve sleeve and operable, in response to an increase of pressure in said branch conduit means, to exert a valve opening force on said valve sleeve and cause said valve sleeve to move to an open position.

4. A swivel control unit for controlling the flow of well fluid from a wellhead comprising:

a generally cylindrical swivel body;

a rotatable, generally tubular body, extending through said swivel body in generally coaxial relationship therewith;

said generally tubular body including

a central bore through which well fluid is conducted to the wellhead and

discharge port means through which said well fluid is removed from said central bore outwardly from said tubular body;

means to secure said swivel body against rotation;

said swivel body including exit port means through which said well fluid passes;

passage means connecting said discharge port means with said exit port means;

a tubular valve sleeve supported by said swivel body and said tubular body and adapted to control the flow of said well fluid through said passage means from said discharge port means to said exit port means; and

a manual valve operable to control the flow of well fluid through said central bore to said discharge port means.

5. The swivel control unit of claim 4, further comprising:

a spring supported by said swivel body; and

an annular, axially extending chamber including said passage means and defined between said generally tubular body and said swivel body, within which chamber said spring and said valve sleeve are supported;

said generally tubular body including pressure port means; and

a portion of said well fluid being operable to pass through said pressure port means and into said chamber, to thereby communicate to said valve sleeve the pressure of the fluid flow in said central bore, so that said thus communicated pressure and the pressure exerted by said spring act against said valve sleeve tending to close said valve means sleeve and thereby interrupt the flow of well fluid through said passage means from said discharge port means to said exit port.

6. The swivel control unit of claim 5, wherein:

said valve sleeve comprises

a piston including an annular head portion and two annular, axially extending, sleeve portions directed oppositely away from said head portion.

7. The swivel control unit of claim 6, wherein:

said chamber further includes a first annular, axially extending variable volume chamber portion of said annular, axially extending chamber, into which said portion of said well fluid passes from said pressure port means;

said first variable volume chamber portion telescopingly receives one end of one of said piston sleeve portions.

8. The swivel control unit of claim 7, wherein:

said chamber includes a second, annular, axially extending variable volume chamber portion into which an actuating fluid is passed; and

said actuating fluid is operable to exert a pressure against said piston head portion in a direction opposite to the pressure exerted by said portion of said well fluid and said spring, to thereby open said valve sleeve and establish the flow of well fluid through said passage means from said discharge port means to said exit port means.

9. The swivel control unit of claim 8, wherein:

the pressure exerted on said piston head by said actuating fluid is less than the pressure exerted on said one end of said one piston sleeve portion by said portion of said well fluid.

10. The swivel control unit of claim 7, wherein:

said passage means comprises a third, annular, axially extending variable volume chamber portion of said annular axially extending chamber; and

the pressure of well fluid in said third chamber portion exerts a pressure against the other end of said one piston sleeve portion in a direction opposite to the direction of pressure exerted by said portion of said well fluid and said spring on said piston, to thereby tend to balance said piston against the pressure exerted by said portion of said well fluid.

11. The swivel control unit of claim 10, further including:

means disposed on said swivel body to indicate the opening and closing of said valve sleeve.

12. The swivel control of claim 10, wherein:

the volume of said first annular axially extending variable volume chamber is at a maximum and the volumes of said second and third annular axially extending variable volume chambers are at a minimum when said valve sleeve is closed; and

the volume of said first annular axially extending variable volume chamber is at a minimum and the volumes of said second and third annular axially extending variable volume chambers are at a maximum when said valve sleeve is open.

13. Well pressure and flow control apparatus for selectively conducting fluid flow into or out of a well while continuously allowing simultaneous rotary movement or vertical manipulations, or both, of the well conduit while flowing said well fluids, comprising:

inner tubular body means adapted to be connected into a conduit string;

an outer flow control sleeve telescopingly encircling said inner body means and adapted to allow said inner body means to rotate relatively unhindered therein;

said flow control sleeve having an internally expanded lower portion arranged to form a valve chamber between said lower portion and said inner body means;

annular cap means attached to the bottom of said expanded portion of said flow control sleeve and arranged to encircle said inner body means and form the lower end of said valve chamber;

tubular valve sleeve means located slidably in said valve chamber and having an upper skirt, a lower skirt and a plurality of differential pressure areas thereon;

spring means within said valve chamber adapted to work against said valve sleeve means and bias said valve sleeve means into a closed position;

well port means in said tubular body communicating from the inner bore of said tubular body through the wall thereof;

flow passage means through the wall of said flow control sleeve arranged to communicate with said well port means;

control pressure port means through the wall of said flow control sleeve and adapted to communicate with said valve chamber; and

said upper skirt on said valve sleeve means being arranged to move between said tubular body means and said flow control sleeve so that in an upper position of said valve sleeve means said skirt passes between said port means and said flow passage means thereby blocking flow therethrough, and in a lower position said skirt is moved out from between said port means and said flow passage means thereby allowing fluid communication therebetween.

14. The apparatus of claim 13 further comprising manually controlled valve means securedly attached to the lower end of said tubular body means and having a central bore therethrough in axial alignment with the inner bore of said tubular body means.

15. The apparatus of claim 13 further comprising cylindrical wear sleeve means securedly attached exteriorly to said inner tubular body means between said body means and said flow control sleeve; thrust bearing means between said tubular body means and said annular cap means arranged to reduce rotational friction therebetweeen; and limit stop means in said valve chamber arranged to limit downward movement of said valve sleeve means.

16. The apparatus of claim 13 wherein said plurality of differential pressure areas numbers three, with the first said differential pressure area being arranged for receiving fluid communicating through said flow passage means, the second said differential pressure area being arranged to receive actuating fluid through said control pressure port means, and the third said differential pressure area being arranged to receive fluid from said inner bore of said tubular body means; with said first and second areas arranged to provide forces tending to bias said valve means into said lower position and said third area arranged to provide a force tending to bias said valve sleeve means into said upper position.

17. The apparatus of claim 16 wherein said first area is substantially equal to said third area and said second area is substantially larger than said third area, with said first area arranged to be exposed only to said flow passage means when said valve sleeve means is in said upper position, and further arranged to be exposed to said well port means and said flow passage means when said valve sleeve means is in said lower position.