US3670814A

US3670814A - Underwater pollution control

Info

Publication number: US3670814A
Application number: US174A
Authority: US
Inventors: Thomas W Childers
Original assignee: Exxon Production Research Co
Current assignee: ExxonMobil Upstream Research Co
Priority date: 1970-01-02
Filing date: 1970-01-02
Publication date: 1972-06-20
Anticipated expiration: 1989-06-20

Abstract

Oil emanating from a submerged well structure which includes a wellhead and a production manifold is recovered and oil pollution of surface waters and neighboring shorelines is prevented by confining the fugitive oil underwater above an oil-water interface under a roof having side curtains and extending over the well structure. One part of the roof is fixed above the production manifold, and another part of the roof is removably secured over the wellhead and includes structure for coacting with a remotely operated running-in device for removably installing and retrieving such roof part. A fluid conduit opened by an oil-water interace-level detecting device drains oil below the roof to a production conduit of the well structure, for example, the production manifold, by gravity flow. The interface level detecting device opens the conduit when the interface reaches a predetermined minimum level below the inlet of the fluid conduit. When the interface climbs to a selected higher level below the inlet with drainage of oil into the conduit, the interface level detecting device closes the inlet valve, preventing sea water from entering the fluid conduit. Means responsive to the interface level shut in production from the well structure if confined oil accumulates to a predetermined maximum interface level below the inlet of the fluid conduit. Attainment of the predetermined minimum level, as indicated by the interface level detector device, may actuate electrical circuitry provided for connection to an indicator placed at a remote accessible location, signaling the occurrence of oil leakage from the submerged well structure and the accumulation of the predetermined minimum volume of fugitive oil. The fluid conduit may have valve means to prevent backflow of oil into the confining area from the well structure production conduit. Valve means may regulate the discharge of oil into the well structure from the fluid conduit. Pumping means may be utilized to force oil from the fluid conduit into the well structure when the production line pressure in the well structure exceeds the hydrostatic pressure at the level of the well structure.

Description

United States Patent Childers 51 June 20, 1972 [54] UNDERWATER POLLUTION CONTROL [72] Inventor: Thomas W. Childers, Woodland Hills,

Calif.

[73] Assignee: Esso Production Research Company,

Houston, Tex.

[22] Filed: Jan. 2, 1970 211 App]. No.: 174

52 u.s.c| ..l66/.5,61/1 F 2,104,660 1/1938 Long et al.... 166/54 2,783,970 3/1957 Gillespie 166/.5 X 3,063,500 1 1/1962 Logan 166/.5 3,389,559 6/1968 Logan... .....6l/l 3,454,083 7/1969 Brooks. ..166/.5 3,461,957 8/1969 West ..l66/.5

Primary Examiner-Marvin A. Champion Assistant Examiner-Richard E. Favreau Attorney-Thomas B. McCulloch, Melvin F. Fincke, John S. Schneider, Sylvester W. Brock, Jr. and Timothy L. Burgess [57] ABSTRACT Oil emanating from a submerged well structure which includes a wellhead and a production manifold is recovered and oil pollution of surface waters and neighboring shorelines is prevented by confining the fugitive oil underwater above an oil-water interface under a roof having side curtains and extending over the well structure. One part of the roof is fixed above the production manifold, and another part of the roof is removably secured over the wellhead and includes structure for coacting with a remotely operated running-in device for removably installing and retrieving such roof part. A fluid conduit opened by an oil-water interace-level detecting device drains oil below the roof to a production conduit of the well structure, for example, the production manifold, by gravity flow. The interface level detecting device opens the conduit when the interface reaches a predetermined minimum level below the inlet of the fluid conduit. When the interface climbs to a selected higher level below the inlet with drainage of oil into the conduit, the interface level detecting device closes the inlet valve, preventing sea water from entering the fluid conduit. Means responsive to the interface level shut in production from the well structure if confined oil accumulates to a predetermined maximum interface level below the inlet of the fluid conduit. Attainment of the predetermined minimum level, as indicated by the interface level detector device, may actuate electrical circuitry provided for connection to an indicator placed at a remote accessible location, signaling the occurrence of oil leakage from the submerged well structure and the accumulation of the predetermined minimum volume of fugitive oil. The fluid conduit may have valve means to prevent backflow of oil into the confining area from the well structure production conduit. Valve means may regulate the discharge of oil into the well structure from the fluid conduit. Pumping means may be utilized to force oil from the fluid conduit into the well structure when the production line pressure in the well structure exceeds the hydrostatic pressure at the level of the well structure.

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UNDERWATER POLLUTION CONTROL BACKGROUND OF THE INVENTION l. Field of the Invention The present invention relates to underwater well structures, and more particularly, to underwater pollution control and apparatus therefor to be extended over such well structures.

2. Description of the Prior Art If oil produced from offshore strata escapes subsea well production facilities and rises to form oil slicks on surface waters, it may pollute not only those waters but neighboring shorelines. Avoidance of this condition is imperative, yet leakage from submerged production equipment may not be detected until an oil slick appears on the surface of the sea. Minor but continuing leaks of production equipment may not produce a noticeable surface slick, and large amounts of production may be lost as time passes.

SUMMARY OF THE INVENTION In view of the above problems associated with the subsea production of oil, it is an object of the invention to provide for the capture and confinement underwater of oil escaping into the sea from one or more'submerged well structures, thereby preventing oil pollution of surface waters and neighboring shorelines.

Another object of the invention is to provide for the early detection of oil emanating from one or more submerged well structures.

A further object of the invention it to provide for the accumulation and local recovery, free of sea water, of oil which has escaped from one or more of submerged well structures.

Still another object of the invention is to provide for the shutting in of production from a loss of oil from a submerged well structure.

These objects are achieved in the present invention by provision of apparatus extending over a submerged well structure for confining fugitive oil from said well structure underwater above an oil-water interface with the further provision of apparatus responsive to the level of that interface for shutting in production from that well structure when that interface is at a predetermined maximum volume within the confining means; by the additional provision of apparatus for removing oil from its confinement above the oil-water interface when a predetermined minimum of oil has accumulated and for discharging that oil back into the well structure; and by the further provision of means for electrical connection to an indicator at a remote accessible location for actuating that indicator when the predetermined minimum of oil has accumulated, signaling a remote accessible location that the well structure is losing oil.

This invention possesses many other advantages, and has other objects in addition to the objects already described, all of which may be made more clearly apparent from a specific consideration of preferred forms in which the invention may be embodied. These forms are shown in the drawings described below which accompany and form part of the present specification. These forms are then described in detail for the purpose of illustrating the general principles of the invention; it is to be understood, however, that the detailed description of the preferred embodiments is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

DESCRIPTION OF THE DRAWINGS taken along the lines 3-3 submerged wells in the event of FIG. 4 illustrates the installation of a plurality of underwater pollution control apparatuses for a plurality of subsea wells;

FIG. 5 is an enlarged isometric view of an oil removal line inlet valve of the apparatus of FIG. 2;

FIG. 6 is an alternative arrangement for oil removal lines of the apparatus of FIGS. 1 and 2;

FIG. 7 is a pump arrangement for use in connection with oil retrieval from the apparatus of FIG. 1 and 12;

FIG. 8 illustrates the installation of a portion of the underwater pollution control apparatus, shown in longitudinal section;

FIG. 9 is a rear elevational view taken along the lines 9-9 of FIG. 8;

FIG. 10 is an enlarged longitudinal section of the running-in tool illustrated in FIG. 8;

FIG. 11 is a top elevational view taken along the lines 1 1- 1 l of FIG. 10;

FIG. 12 is a longitudinal sectional and side elevational view depicting the installation of a portion of the underwater pollution control apparatus for opposed submerged well structures;

FIGS. 13(a)-(c) illustrate another method of installing a portion of the pollution control apparatus;

FIG. 14 is a cross sectional view taken along the lines 14- 14 of FIG. 7(a);

FIG. 15 is an enlarged side elevational view of a portion of the pollution control apparatus illustrated in FIGS. 13(a )-(c); and

FIG. 16 is an elevational view to the rear taken along the lines 16--16 of FIG. 12.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An underwater pollution control device A is illustrated in the drawings (see especially FIGS. 1 and 2) which is adapted to be installed over a submerged well structure B. The submerged well structure 8 includes a wellhead 10, which surmounts a well 11 illustrated as a dual completion well;

production lines

12, 13, which produce dual completion well 11; and production manifolds 14, 15, into which production from

production lines

12, 13 feeds by way of

jumper pipes

16, 17.

Production manifolds

14, 15 connect into pipelines which lead to storage tanks which may be submerged, located above the ocean's surface on a fixed or floating platform, or onshore. Production through

production lines

12, 13 is regulated by

production control valves

18, 19, and feed through

production manifolds

14, 15 is regulated by

production manifold valves

20, 21.

Production control valves

18, 19 and

production manifold valves

20, 21 are linked by hydraulic lines (e.g. lines 22, 23) to an electro-hydraulic production control module 24, which transmits and receives monitoring and control signals, respectively, to and from a remote accessible site, such as a fixed or floating platfonn or an onshore station, by means of a multi-oonductor signal power cable 25. The submerged well structure and its amociated production control equipment are supported on ocean floor 26 by means of a template structure 27, which includes a base 28 mounting front and

rear guideposts

29a and 29b, respectively, from which guide wires 30 are extended to a fixed or floating platform on the ocean: surface.

The underwater pollution control device A includes a roof 31 extending over the well structure B. Referring particularly to FIGS. 1 and 2, roof 31 takes the form of an inverted pan, with a top surface 32 and side curtains 33, and includes a portion 34 over the manifold and a portion 35 over the wellhead. The manifold cover pan 34 is aflixed over production manifold: 14, 15, suitably by structural members 36 secured to the header portion 37 of the uppermost manifold 14. Wellhead cover pan 35 is removably secured above wellhead 10 by structure hereinafter described coacting with the

guideposts

29a and 29b of the template 27, in order that the wellhead cover pan 35 may be removed for vertical re-entry to perform work-over operations and the like.

Roof 31 may take several attitudes. In the embodiment illustrated in FIG. 1, roof 31 has a sloped configuration over wellhead structure B, the roof ascending from the portion 35 covering the wellhead to the portion 34 covering the manifold. The forward portion 38 of the wellhead cover pan 35 is inserted under the rear portion 39 of the manifold cover pan 34 to form a continuous and upwardly inclining passage from wellhead cover pan 35 to manifold cover pan 34 by which oil fluids, of lighter specific gravity than water, and fugitive from well structure B, are directed to flow by gravity upward under manifold cover pan 34. Manifold cover pan 34 includes as oil fluid collecting structure a transverse passage 40 provided by a gutter 41 formed in the forward portion of manifold cover pan 34. As illustrated in FIG. 3, gutter 41 converges from side curtains 33 of manifold cover pan 34 to drain into a standpipe 42 which empties into a roof receiving chamber 43. For a multi-wellhead template, one manifold cover pan 34 may receive oil percolating upward from a plurality of wellhead cover pans 35, as illustrated in FIG. 4, in which centrally peaked gutter 41 delivers tributary oil from any

roof portion

34 or 35 to the central roof receiving chamber 43.

In the embodiment illustrated in FIG. 2, roof 31 has a level configuration over wellhead structure B. The forward, near and lateral edges of the top 32 of each portion of roof 31, specifically manifold cover pan,34 and wellhead cover pan 35, are provided with dependent side curtains 33. In this form of roof, each

portion

34 and 35 of the roof serves as a collecting module for rising fugitive oil fluids. The manifold cover pan 34 largely collects oil fluids rising from the manifold portion of the submerged well structure B, and the wellhead cover pan 34 largely collects oil fluids rising from the wellhead of wellhead structure B. In either embodiment, that of FIG. 1 or FIG. 2, the manifold cover pan 34 and the wellhead cover pan 35 of the roof 31 cooperatively serve to capture oil escaping from well structure 8 and to confine the oil underwater above an oil-water interface 44 bounded by at least one of them.

Oil confined under roof 31 above oil-water interface 44 is removed from its underwater confinement and discharged into well structure B free of sea water by means of a fluid conduit 45 connecting roof 31 and well structure B. Referring to FIG. 1, fluid conduit 45 has an inlet 46 opening into the receiving chamber 43 of roof 31 and an outlet 47 opening into a production line of well structure B, suitably down-hole production tubing,

wellhead production lines

12, 13, or, as illustrated, into header portion 37 of production manifold 14. Admission into inlet 46 of oil above interface 44 is controlled by a normally closed inlet valve 48 operatively associated with an oil-water interface level detecting device 49 which opens inlet valve 48 when the oil-water interface 44 reaches a predetermined minimum level below inlet 46 and closes inlet valve 48 when interface 44 climbs to a selected level below inlet 47 with drainage of oil into fluid conduit 45. Suitably, interface level detecting device 49 may include a relay for electrically actuating valve 48 on closure of the relay by downward movement of float 50 on pivot arm 51 to the predetermined minimum location within side curtains 33 of roof 31 below inlet 46. (Other oil-water interface level detecting devices suitably include solid state electrical micro switches, capacitance probe-type oil detectors, magnetic permeability switches and the like, as known to the art, although the float actuated mechanical link is preferred for its long service life and reliability.) When inlet 46 is opened, oil above interface 44 is driven into fluid conduit 45 by the heavier sea water if line pressure in production manifold 14 is less than the hydrostatic pressure of the water at the level of the underwater structure. If line pressure is greater than the hydrostatic pressure at that level, oil from the production manifold may backflow through fluid conduit 45, driving interface level 44 down within receiving chamber 43 to a predetermined maximum level to which interface level detecting device 49 responds, as by closure of a second stage relay, and engages circuitry leading to production control unit 24 to shut in production from well structure B. Response of interface level detecting device 49 to attainment of the predetermined maximum level may also engage circuitry which may be provided for electrical connection to an indicator installed at a remote accessible location to signify accumulation under roof 31 of a predetermined maximum volume of oil above the predetermined maximum level. Alternatively, as illustrated in FIG. 1, a capacitance probe 52 or other level detecting means may be separately installed in the lower portion of the receiving chamber 43, instead of being integrated with the structure of the device 49 detecting the predetermined minimum level, for connection to electrical circuitry leading to a remote indicator and/or operative connection to production control unit 24. A check valve 53 may suitably be provided in fluid conduit 45 to prevent backflow into chamber 43 of oil from production manifold 14. If so, when inlet 46 is opened on attainment of the predetermined minimum volume and forward flow through fluid conduit 45 is prevented by a higher pressure in the production line, well structure 8 will be shut in by continued collection of fugitive oil by roof 31 if the predetermined maximum volume interface level is attained.

Referring to FIG. 2, a preferred construction of fluid conduit 45 is illustrated in which outlet 47 is normally closed by outlet valve 54. In the modular construction of roof 31 in the embodiment depicted in FIG. 2, fluid conduit 45 has

dual inlets

55, 56 opening respectively into the oil confining areas of wellhead cover pan 35 and manifold cover pan 34. Fluid conduit inlets 55 and 56 are normally closed, respectively, by

inlet valves

57 and 58. Each

inlet valve

57, 58 operates independently of the other inlet valve to admit oil above the interface level, respectively, of wellhead cover pan 35 and manifold cover pan 34 into fluid conduit 45. As best seen in FIG. 5, the inlet valves (for example, inlet valve 58) are directly operated by float controlled linkage comprising a pivot arm 59 which moves according to the disposition of a terminally attached float 60, float 60 following the level of the oil-water interface within the confines of roof 31. As float 60 descends with a falling interface level 44, pivot arm 59 rotates shaft 61. When interface 44 reaches a predetermined minimum level, shaft 61 opens the inlet valve. Shaft 61 simultaneously closes a relay in switch 62 which is provided for electrical connection to an indicator at a remote accessible location to actuate that indicav tor, signaling attainment by interface 44 of the predetermined minimum location below inlet 56. Responsive to that signal, an operator at the remote accessible site compares the pressure in the production lines of the wellhead structure B, for example, in manifold 14, and ifthe production line pressure does not exceed hydrostatic pressure at the level of well structure B, the operator engages circuitry in production control unit 24 through power-signal cable 25 to open valve 54 in fluid conduit 45, thereby permitting discharge from fluid conduit 45 through outlet 47 into production manifold 14 of oil fluids admitted to fluid conduit 45 on the opening of the

particular inlet valve

57 or 58. Elevation of float 60 to a selected higher level between the predetermined minimum level and

inlet

55 or 56 turns shaft 61 to open the relay and close the

particular inlet valve

57 or 58, preventing sea water from entering fluid conduit 45. A check valve 53 may be provided, as in the embodiment of FIG. 1, to prevent back-flow of oil into the oil confinement area under roof 31 in the event that a surge of production line pressure exceeds the environmental hydrostatic pressure. In the arrangement depicted in FIG. 2, if the pressure in the production lines exceeds the local hydrostatic pressure when inlet valve 58 opens, switch 62 being actuated to signify that event to a remote operator, the remote operator will not open outlet valve 54, and oil fluids will continue to accumulate within the confines of the

portion

34 or 35 of roof 31 in which the inlet valve is opened. If oil accumulates to a predetermined maximum level between the lower edges of side curtains 33 and the

particular inlet

55 or 56, a level sensing device will respond to engage circuitry leading to production control unit 24 to shut in production from the well structure B. The level sensing device may suitably be either integrally incorporated in

level detecting device

57, 58 or separately installed, such as capacitance probes 63 and 64 respectively located in the lower confining areas of wellhead cover pan 35 and manifold cover pan 34.

A more preferred construction of fluid conduit 45 is illustrated in FIG. 6 which permits oil fluids to be discharged into the well structure when production line pressure exceeds local hydrostatic pressure. In addition, FIG. 6 illustrates by dashed lines a construction that permits discharge of oil fluids from fluid conduit 45 into whichever one of a plurality of production lines of well structure B has a lower line pressure than the hydrostatic pressure at the level of the well structure. Referring to FIG. 6, fluid conduit 45, provided with an outlet valve 54 as illustrated in FIG. 2, is further provided with a bypass conduit 65 which bypasses outlet valve 54, entering fluid conduit 45 ahead of outlet 47. A suitable submersible pump 66 is linked into bypass line 65. Check

valves

67 and 68 are installed, respectively, in bypass line 65 between pump 66 and where line 65 re-enters fluid conduit 45, and in fluid conduit 45 between outlet valve 54 and the entrance of line 65 with fluid conduit 45. With this construction, when alerted by signal that an inlet valve has opened admitting oil fluids into fluid conduit 45, a remote operator may discharge oil fluids from fluid conduit 45 into production manifold 14 without backflow, even through line pressure in manifold 14 exceeds local hydrostatic pressure. The operator leaves valve 54 closed, and energizes pump 66 in line 65, pumping oil fluids in line 45 through bypass line 65 to the entrance of line 65 into line 45 and thence into header 37 of manifold 14 through outlet 47. Check

valves

67 and 68 prevent damage to pump 66 and outlet valve 54, respectively, from abnormally high pres sure surges in the production lines.

The preferred construction of FIG. 6 is further illustrated by dashed lines in which fluid conduit 45 is depicted as having a plurality of outlets 47 and 47' opening into a plurality of production manifolds 14, 15 of well structure B. Structure depicted by the dashed lines corresponding to structure illustrated by the solid lines of FIG. 6 is identically enumerated, but differentiated with superscript prime marks. In the arrangement shown by dashed lines, the operator, when signaled that an inlet valve has opened, may poll the pressures of the various producing lines, and if the line pressure in any one of the plurality of production lines is less than the hydrostatic pressure at well structure level, the operator may route the oil fluids in fluid conduit 45 to that lesser pressure production line by actuating only the particular outlet valve controlling the outlet into that production line. For example, if in FIG. 6 the pressure in manifold 15 is less than hydrostatic pressure at the level of well structure B and the pressure in manifold 14 exceeds that hydrostatic pressure, outlet valve 54 is maintained closed and outlet valve 54' is opened, permitting oil fluids in fluid conduit 45 and 45' to be driven by gravity into the header of production manifold 14 through outlet 47'. In combination with bypass line 65 and pump 66, the structure illustrated by dashed lines permits the operator to chose whether to operate pump 66 or not, unles all producing line pressures exceed local hydrostatic presure, in which case pump 66 is used if well structure B is not to be automatically shut-in.

For use as an underwater pump 66, a small triplex or a centrifugal pump driven by either a submersible electric motor or a submersible hydraulic motor immersed in an oil-filled pressure balance container is suitable. Another suitable pump system is schematically depicted in FIG. 7, in which pressure in the production manifold header 37 exceeding the hydrostatic pressure of the water at the well structure level is utilized to create a Venturi eflect. Referring to FIG. 7, reference numeral 37 indicates the manifold production header of well structure B in FIGS. 1 and 2. A through flowline (TFL) service line 70 transmitting fluids from a remote production facility into wellhead by valving apparatus familiar to the art is provided with a crossover line 71 joining TFL line 70 with manifold production header 37. Crossover line 71 con tains a constriction 72 which receives the outlet 47 of fluid conduit 45. Outlet 47 is normally closed by outlet valve 54 which is operated by hydraulic lines leading to production control unit 24. Intermediate the takeoff of crossover line 71 from 'I'FL line 70 and constriction 72, crossover line 71 is normally closed by crossover line valve 73 controlled by hydraulic lines running from production control unit 24. Flow into crossover line 71 of production fluids from TFL line 70 and from crossover line 71 into manifold production header 37 is permitted when crossover line valve 73 is opened by remote operation through production control unit 24. Flow of production fluids through constriction 72 in line 71 creates a pressure drop at constriction 72. Actuation of valve 54, opening the outlet of fluid conduit 45, creates a suction in fluid conduit 45 which draws oil above oil-water interface 44 through fluid conduit 45 into crossover line 71 and thence into production manifold header 37. Although not specifically illustrated in FIG. 6, it will be understood that the inlet 45 is guarded by an inlet valve as in FIGS. 1 and 2.

As hereinbefore stated, manifold cover pan 34 is aifixed over production manifolds l4, l5. Suitably, manifold cover pan 34 may be attached to its mount prior to lowering of the well structure B on template 27 into place on ocean bottom 26.

Removable wellhead cover pan 35 is installed after well structure 8 and manifold cover pan 34 are set in place on ocean bottom 26. In FIGS. 8-12, the operation of structure of wellhead cover pan 35 coacting with a remotely operated running and retrieving tool for removably securing wellhead cover pan 35 above wellhead 10 is illustrated for the embodiment of wellhead cover pan 35 depicted in FIG. 1. Referring particularly to FIGS. 8 and 9, wellhead cover pan 35 is pivotally hinged in its forward portion by means of a plurality of hinge pins seated in mounting rings 76 affixed to confronting sides of guide sleeves 77. 'Ihe top surface 32 of wellhead cover pan 35 mounts a crossbar 78 between upstanding ears secured to the rear of the center of wellhead cover pan 35. A semicircular stop 80 is braced behind ears 79 at an acute angle with top surface 32 by a brace 81.

Coacting with the structure of wellhead cover pan 35 is a running and retrieving tool indicated generally by reference numeral 82. Referring to FIG. 8, tool 82 includes a central tubular body or mandrel 83 connected to a tubular running-in string 84, as by threaded attachment of an upward box in mandrel 38 with a lower pin end of the running-in string 84. Referring to FIG. 9, the lower end of tubular mandrel 83 is constituted as a tubular neck 85 tenninating in a piston head 86, which attaches a plurality of dependent, normally extended, opposed spring fingers 86. A latching sleeve 87 surrounds piston head 85 in a larger inner diameter lower portion of the sleeve and surrounds lower neck 84 of tubular body 83 in a smaller inner diameter upper portion, which includes in its inner circumference a circular recess 88 housing a suitable seal ring or gasket 89, such as an O-ring. A circumferential recess 90 is provided in the outer circumference of piston head 85 to house a suitable seal ring or gasket 91.

Sealing members

89 and 91 together prevent leakage of fluid between tubular body 83 and latching sleeve 87. Spring fingers 86 are provided with outside stops 92 which limit downward extension of latching sleeve 87 on neck 84 and piston head 85 of tubular body 83. Force giving rise to a downward extension of latching sleeve 87 is imparted to sleeve 87 by a helical spring encompassing neck 84 and compressed between

outer shoulders

94 and 95, respectively, of tubular body 83 and latching sleeve 87. In full extension on neck 84 and piston head 85, latching sleeve 87 defines an annular space 96 between its inner shoulders 97 and the upper inner shoulders 98 of piston head 85. In operation, hydraulic fluid is pumped through tubular passageway 99 into annular space 97 to retract latching sleeve 87 on the circumference of piston head 85 against the compressive force of spring 93, thereby opening spring fingers 86 for closure about crossbar 79 on wellhead cover pan 35. Hydraulic fluid is then withdrawn from annular space 97 in balanced measure against the force of spring 93 so that latching sleeve 87 descends about piston head 85 until the downward extension of its movement is limited by stops 92, thereby closing and locking spring fingers 86 inwardly about crossbar 78 of wellhead cover pan 35. As illustrated in FIG. 8, running-in string 84, when hoisted, permits the wellhead cover pan to rotate on pins 75 mounted to guide sleeves 77 to produce a tilted attitude which reduces the projected area of the wellhead cover pan such that, when the wellhead cover pan is run in by string 84 guided by guide sleeves 77 running on guide wires 30 from guidepost 29a, the leading edge 38 of the wellhead cover pan 35 clears the rear edge 39 of fixed manifold cover pan 35. During descent, the tilted attitude of the wellhead cover pan is maintained by abutment of semicircular stop 80 against latching sleeves 87 of tool 82, as depicted by FIGS. 7 and 10. Descent of wellhead cover pan 35 is stopped when guide sleeve 77 impinges upon limit ring 100 attached to guidepost 29a. Further downward movement of running-in string 84 rotates wellhead cover pan 35 about the axis of hinge pins 75, semicircular stop 80 disengaging latching sleeve 87, until wellhead cover pan 35 is deposited on a cross member 101 spanning rear guidepost 29b. Tool 82 is then released from crossbar 78 of wellhead cover pan 35 by pumping hydraulic fluid into annular space 97 to retract latching sleeve 87, permitting spring fingers 86 to expand outwardly to release the crossbar. Running-in string 84 is then retrieved to the surface. As reference to FIG. 12 taken with FIG. 4 illustrates, wellhead cover pans 35 may be so installed in back-to-back multi-wellhead template structures.

Alternative structure of wellhead cover pan 35 for coacting with running and retrieving tool 82 for removably securing wellhead cover pan 35 above wellhead in the embodiment of wellhead cover pan 35 depicted in FIG. 1 is illustrated in FIGS. 13(a)l3(c) taken with FIGS. 14 and 15. In this form, wellhead cover pan 35 is run in without the necessity of using a conventional guidepost system. As in the embodiment discussed in connection with FIGS. 8-12, wellhead cover pan 35 is provided with an off-center crossbar 78 secured to top surface 32 by a pair of cars 79. Attachment of the running tool to off-center crossbar 78 as shown in FIG. 13(a) causes the forward edge 38 of the cover 35 to rotate down to a tilted attitude reducing the projected area of cover 35 so that, when lowered, it clears the rear edge 39 of the fixed manifold cover pan 34. Referring to FIG. 14 taken with FIG. 13(a), the undersurface of top 32 of wellhead cover pan 35 is provided with a pair of notched ribs 102 longitudinal and inboard of lateral side curtains 33. Each of the ribs 102 is tapered to define a notch 103 between a leading anterior portion 104 and a trailing posterior portion 105. As the wellhead cover pan 35 is lowered, the leading portion 104 contacts a cross member 106 rovided in structure erected on template 27 (FIG. 13(a)). Leading portion 104 then slides forward on its edge until it is stopped by notch 103. As lowering continues, wellhead cover pan 35 rotates about notch 103 so that the forward edge 38 of the cover 35 is under the fixed manifold cover pan 34, as depicted in FIG. 13(0). In this position, the rear end of top surface 32 rests on a cross support member of framework on template 27. As depicted in FIG. 15, notch 103 may include a recess within rib 102 for hooking rib 102 on cross member 106 to prevent slippage. Wellhead cover pan 35 may be run in using an external guidance system other than the conventional guidepost system.

Installation of the wellhead cover pan 35 depicted for the embodiment of FIG. 2 proceeds according to conventional running and retrieving of guide sleeves on guideposts. Referring to FIG. 2, running-in and retrieving tool 82 may coact with a center mounted crossbar 78' mounted to top surface 32 of cover 35 on upstanding ears 79'. Referring to FIG. 16, side curtains 33 are secured, as by wellments, to guide sleeves 110 70 which guide the lowering of wellhead cover pan 35 by following guide wires 30 onto guide posts 34, which are fitted with limit stops 111. In the embodiment of FIG. 2, as in the embodiments of FIG. I, the fluid conduit 45 is mounted with equipment installed on template 27 when template 27 is set on ocean bottom 26.

After installation of underwater pollution control device A over submerged well structure B, fluid conduit 45 is purged of sea water by remotely actuating, in the embodiment of FIG. 1, inlet valve 48, and in the embodiment of FIG. 2, outlet valve 54 and

inlet valves

57, 58, momentarily to open those valves when pressure in the production line system exceeds hydrostatic pressure at the level of the well structure 8, production fluids from the production lines forcing sea water from fluid conduit 45. fire cooperative action of oil-water interface level detecting device 49 and the inlet valve (3) of the particular structure thereafter prevent entrance of sea water into fluid conduit 45.

Having fully and particularly described apparatus which accomplish the hereinbefore stated objects of this invention, and having disclosed the best modes contemplated for the purposes of this invention, I claim and desire to secure by Letters Patent:

1. An underwater pollution control apparatus for a submerged well structure comprising:

a. confining means for confining fugitive oil from said well structure underwater above an oil-water interface, said confining means extending over said well structure, and

b. responsive means responsive to the level of said interface for shutting in production from said well structure when said interface is at a predetermined maximum level within said confining means.

2. The underwater pollution control apparatus of claim 1 further comprising means for electrical connection to an indicator at a remote accessible location for actuating said indicator when said interface is at said predetermined maximum oil level.

3. An underwater pollution control apparatus for a submerged well structure, comprising:

b. oil removing means having an inlet opening into said confining means above said oil-water interface and an outlet opening into said well structure for removing said oil from said confining means and discharging it into said well structure free of sea water, said oil removing means including means responsive to the level of said oil-water interface for admitting oil through said outlet where said interface is at a predetermined minimum level below said inlet and for closing said inlet when said interface is at a selected level below said inlet higher than said predetermined minimum level.

4. The underwater pollution control apparatus of claim 3, further comprising pump means operatively associated with said fluid conduit means for pumping oil from said fluid conduit means into said well structure.

5. The underwater pollution control apparatus of claim 3 further comprising responsive means responsive to the level of said interface for shutting in production from said well structure when said interface is at a predetermined maximum level within said confining means below said inlet.

6. The underwater pollution control apparatus of claim 5 in which said oil removing means includes means for preventing backflow through said inlet of oil in said oil removing means.

7. The underwater pollution control apparatus of claim 5, further comprising pump means operatively associated with said fluid conduit means for pumping oil from said fluid conduit means into said well structure.

8. The underwater pollution control apparatus of claim 5 further comprising means for electrical connection to an indicator at a remote accessible location for actuating said indicator when said interface is at a predetermined minimum location below said inlet.

9. The underwater pollution control apparatus of claim 8, further comprising pump means operatively associated with said fluid conduit meats for pumping oil from said fluid confixed manifold cover pan 34 and lowered with the production duit means into said well structure.

10. The underwater pollution control apparatus of claim 8 in which said oil removing means includes means for controlling the discharge through said outlet into said well structure of oil from said oil removing means.

11. The underwater pollution control apparatus of claim 10 further comprising regulative means operatively associated with said fluid conduit means for preventing backflow through said inlet of oil in said fluid conduit means.

12. The underwater pollution control apparatus of claim 1 1, further comprising pump means operatively associated with said fluid conduit means for pumping oil from said fluid conduit means into said well structure.

13. An underwater pollution control apparatus extended over a submerged well structure including a wellhead and at least one production manifold, comprising:

a. a roof having side curtains, including a manifold portion of said roof which is affixed to said well structure above said manifold, and a wellhead portion of said roof which is removably secured over said wellhead and has means for coacting with a running-in device for removably installing and retrieving said wellhead portion, said portions of said roof being operatively associated to confine above an oil-water interface bounded by at least one of them essentially all oil escaping from said submerged well structure;

b. fluid conduit means having at least one outlet opening into said well structure and at least one inlet opening into at least one of said portions of said roof for conducting oil from above said interface into said well structure;

c. level detecting means arranged under at least one of said portions of said roof for detecting when said interface is at a predetermined level;

d. an inlet control means operatively associated with said fluid conduit means and operatively connected with said level detecting means for admitting oil through said inlet into said fluid conduit means in response to a detection by said level detecting means that said interface is at a predetermined minimum level below said inlet and for closing said inlet in response to a detection by said level detecting device that said interface is at a selected level below said inlet that is higher than said predetermined minimum level; and

e. means operatively connected to said level detecn'ng means for shutting in production from said well structure in response to a detection by said level detecting means that said interface is at a predetermined maximum level below said inlet within the confines of said roof.

14. The underwater pollution control apparatus of claim 13 further comprising regulative means operatively associated with said fluid conduit means for preventing backflow through said inlet of oil in said fluid conduit means.

15. The underwater pollution control apparatus of claim 13 further comprising pump means operatively associated with said fluid conduit means for pumping oil from said fluid conduit means into said well structure.

16. The underwater pollution control apparatus of claim 13 further comprising means for electrical connection to an indicator at a remote accessible location for actuating said indicator in response to a detection by said level detecting means that said interface is at said predetermined maximum level.

17. The underwater pollution control apparatus of claim 13 further comprising means for electrical connection to an indicator at a remote accessible location for actuating said indicator in response to a detection by said level detecting means that said interface is at said predetermined minimum level.

18. The underwater pollution control apparatus of claim 17 further comprising pump means operatively associated with 5 said fluid conduit means for pumping oil from said fluid conduit means into said well structure.

19. The underwater pollution control apparatus of claim 17 further comprising an outlet control means operatively as sociated with said fluid conduit means which controls the admission of oil from said fluid conduit means into said well structure through said outlet.

20. The underwater pollution control apparatus of claim 19 further comprising regulative means operatively associated with said fluid conduit means for preventing backflow through said inlet of oil in said fluid conduit means.

2!. The underwater pollution control apparatus of claim 19 further comprising pump means operatively associated with said fluid conduit means for pumping oil from said fluid conduit means into said well structure and regulative means operatively associated with said fluid conduit means for preventing backflow through said inlet of oil in said fluid conduit means.

22. The underwater pollution control apparatus of claim 13 in which said roof is upwardly inclined from said portion over said wellhead to said portion over said manifold whereby oil confined under the portion of said roof over said well head passes by displacement of water to the portion of said roof over said manifold.

23. The underwater pollution control apparatus of claim 22 in which said portion of said roof above said manifold includes accumulating means for accumulating oil above an oil-water interface.

24. A method of recovering oil emanating into subsurface waters from a submerged well structure and preventing oil 3 5 pollution of surface waters, comprising:

confining fugitive oil from said submerged well structure underwater immediately above said structure, accumulating the oil until a predetermined minimum of volume is obtained, and then discharging at least a portion of the accumulated oil into said submerged well structure while preventing entrance of sea water into such structure.

25. The method of claim 24 further comprising:

accumulating confined fugitive oil not discharged into said submerged well structure until a predetermined maximum volume is attained, and then shutting in production from said submerged well structure in response to the attainment of said predetermined maximum volume.

26. The method of claim 24 further comprising signaling a remote accessible location of the accumulation of said predetermined minimum volume of fugitive oil.

27. The method of claim 26 in which said oil is discharged into said submerged well structure on instruction from said 55 remote accessible location.

28. A method for preventing pollution of surface waters by oil from a submerged well structure, comprising:

confining fugitive oil from said well stnicture underwater immediately above said structure,

accumulating said oil until a predetermined maximum volume is obtained, and then shutting in production from said submerged well structure in response to the attainment of said predetermined maximum volume.

65 e e e e e

Claims

1. An underwater pollution control apparatus for a submerged well structure comprising: a. confining means for confining fugitive oil from said well structure underwater above an oil-water interface, said confining means extending over said well structure, and b. responsive means responsive to the level of said interface for shutting in production from said well structure when said interface is at a predetermined maximum level within said confining means.

3. An underwater pollution control apparatus for a submerged well structure, comprising: a. confining means for confining fugitive oil from said well structure underwater above an oil-water interface, said confining means extending over said well structure, and b. oil removing means having an inlet opening into said confining means above said oil-water interface and an outlet opening into said well structure for removing said oil from said confining means and discharging it into said well structure free of sea water, said oil removing means including means responsive to the level of said oil-water interface for admitting oil through said outlet where said interface is at a predetermined minimum level below said inlet and for closing said inlet when said interface is at a selected level below said inlet higher than said predetermined minimum level.

9. The underwater pollution control apparatus of claim 8, further comprising pump means operatively associated with said fluid conduit means for pumping oil from said fluid conduit means into said well structure.

12. The underwater pollution control apparatus of claim 11, further comprising pump means operatively associated with said fluid conduit means for pumping oil from said fluid conduit means into said well structure.

13. An underwater pollution control apparatus extended over a submerged well structure including a wellhead and at least one production manifold, comprising: a. a roof having side curtains, including a manifold portion of said roof which is affixed to said well structure above said manifold, and a wellhead portion of said roof which is removably secured over said wellhead and has means for coacting with a running-in device for removably installing and retrieving said wellhead portion, said portions of said roof being operatively associated to confine above an oil-water interface bounded by at least one of them essentially all oil escaping from said submerged well structure; b. fluid conduit means having at least one outlet opening into said well structure and at least one inlet opening into at least one of said portions of said roof for conducting oil from above said interface into said well structure; c. level detecting means arranged under at least one of said portions of said roof for detecting when said interface is at a predetermined level; d. an inlet control means operatively associated with said fluid conduit means and operatively connected with said level detecting means for admitting oil through said inlet into said fluid conduit means in response to a detection by said level detecting means that said interface is at a predetermined minimum level below said inlet and for closing said inlet in response to a detection by said level detecting device that said interface is at a selected level below said inlet that is higher than said predetermined minimum level; and e. means operatively connected to said level detecting means for shutting in production from said well structure in response to a detection by said level detecting means that said interface is at a predetermined maximum level below said inlet within the confines of said roof.

18. The underwater pollution control apparatus of claim 17 further comprising pump means operatively associated with said fluid conduit means for pumping oil from said fluid conduit means into said well structure.

19. The underwater pollution control apparatus of claim 17 further comprising an outlet control means operatively associated with said fluid conduit means which controls the admission of oil from said fluid conduit means into said well structure through said outlet.

21. The underwater pollution control apparatus of claim 19 further comprising pump means operatively associated with said fluid conduit means for pumping oil from said fluid conduit means into said well structure and regulative means operatively associated with said fluid conduit means for preventing backflow through said inlet of oil in said fluid conduit means.

24. A method of recovering oil emanating into subsurface waters from a submerged well structure and preventing oil pollution of surface waters, comprising: confining fugitive oil from said submerged well structure underwater immediately above said structure, accumulating the oil until a predetermined minimum of volume is obtained, and then discharging at least a portion of the accumulated oil into said submerged well structure while preventing entrance of sea water into such structure.

25. The method of claim 24 further comprising: accumulating confined fugitive oil not discharged into said submerged well structure until a predetermined maximum volume is attained, and then shutting in production from said submerged well structure in response to the attainment of said predetermined maximum volume.

27. The method of claim 26 in which said oil is discharged into said submerged well structure on instruction from said remote accessible location.

28. A method for preventing pollution of surface waters by oil from a submerged well structure, comprising: confining fugitive oil from said well structure underwater immediately above said structure, accumulating said oil until a predetermined maximum volume is obtained, and then shutting in production from said submerged well structure in response to the attainment of said predetermined maximum volume.