SUBSEA CAPTURE SYSTEM AND METHOD OF USING SAME

Abstract

A subsea capture system, comprising a plurality of leak sources on a sea floor, the leak sources having a density less than sea water; and a plurality of capture devices located above each of the plurality of leak sources, the capture devices comprising a funnel shape comprising a large bottom opening inlet and tapering to a small top opening outlet

Description

BACKGROUND

When oil and gas is spilled into the sea, for example from a leaking tanker ship, a leaking pipeline, from oil seeping from an underground formation, or from oil flowing from a subsea wellhead or blowout preventer, there is a desire to collect the oil and gas and contain and transport or otherwise dispose of the oil and gas to prevent environmental damage to the sea and nearby coastlines. Various systems and methods of collecting spilled oil and gas are known in the art and set forth below:

U.S. Pat. No. 4,405,258 discloses a method for storing a lighter-than-water fluid, e.g., oil, produced from the blowout of an offshore subsea well. The method includes the steps of deploying a containment dome in shallow water near the location of the seabed where the containment dome is to be located. The containment dome as an upper expanded dome-like fluid impervious membrane, a fluid impervious hollow peripheral ring attached to the periphery of the membrane to provide a depending bag-like container, and discrete water drainage means within the bag-like container for connection to pump conduit means therefrom. Wet sand from the seabed is then pumped into the bag-like container, and water is then drained from the wet sand through the water drainage means so as to provide a body of drained sand disposed within the bag-like container and providing a hollow peripheral ring as a hollow peripheral torus acting as a self-supporting structure and as an anchor for the dome-like structural unit. The dome is then charged with a buoyant amount of air and the buoyed dome is floated out to the site where the dome is to be deployed. It is then submerged by controllably releasing the air while substantially simultaneously filling the dome with water, thereby sinking the dome until the lighter-than-water fluid is captured within the dome, while such fluid substantially simultaneously displaces water from within the dome. U.S. Pat. No. 4,405,258 is herein incorporated by reference in its entirety.

U.S. Pat. No. 4,643,612 discloses an oil storage barge having a concave bottom is adapted to be anchored over a subsea well or pipeline that is leaking oil. Flexible skirts extend to the ocean floor, and oil that is trapped under the barge may be stored in the barge or then transferred to another vessel. U.S. Pat. No. 4,643,612 is herein incorporated by reference in its entirety.

U.S. Pat. No. 5,114,273 discloses a protective device installed to or around an offshore drilling platform for oil or gas and the device when in operation to encircle or enclose the platform with a floating containment device and attached oil containment curtain hanging from the device to the ocean floor. The pollution containment device to be submerged normally and activated to the surface when needed. This device will entrap offshore platform pollutants in a short amount of time with a minimum amount of effort and will maintain a clean environment. Other methods of offshore platform pollution containment devices are shown, including permanent non-moving oil pollution containment barriers and activated barriers that operate internally and externally of the oil platform to form an all encompassing barrier from the ocean floor to above the water surface to hold an oil spill to the platform area. U.S. Pat. No. 5,114,273 is herein incorporated by reference in its entirety.

U.S. Pat. No. 5,213,444 discloses an oil/gas collector/separator for recovery of oil leaking, for example, from an offshore or underwater oil well. The separator is floated over the point of the leak and tethered in place so as to receive oil/gas floating, or forced under pressure, toward the water surface from either a broken or leaking oil well casing, line, or sunken ship. The separator is provided with a downwardly extending skirt to contain the oil/gas which floats or is forced upward into a dome wherein the gas is separated from the oil/water, with the gas being flared (burned) at the top of the dome, and the oil is separated from water and pumped to a point of use. Since the density of oil is less than that of water it can be easily separated from any water entering the dome. U.S. Pat. No. 5,213,444 is herein incorporated by reference in its entirety.

U.S. Pat. No. 6,592,299 discloses a method of detecting and locating fresh water springs at sea essentially by taking salinity measurements and by methods and installations for collecting the fresh water. The collection installations comprise an immersed bell-shaped reservoir containing and trapping the fresh water in its top portion, and a pumping system for taking fresh water and delivering the fresh water via a delivery pipe, characterized in that the circumference of the bottom end of the reservoir and/or the circumference of the bottom end of a chimney inside the reservoir and open at its top end and surrounding the fresh water resurgence in part and preferably in full, follow(s) closely the outline of the relief of the bottom of the sea so as to provide leakproofing between the circumference(s) and the bottom of the sea. U.S. Pat. No. 6,592,299 is herein incorporated by reference in its entirety.

There is a need in the art for one or more of the following:

Improved systems and methods for collecting spilled oil and gas from a marine environment, for example collecting spilled oil and gas spilling from a number of locations;

Improved systems and methods for collecting oil and gas spilling from multiple subsea wells;

Improved systems and methods for collecting oil and gas spilling from a subsurface formation located beneath a body of water; and/or

Improved systems and methods for collecting oil and gas spilling from a subsurface formation located beneath a body of water, and then burning the gas and containing the oil in a surface vessel.

SUMMARY OF THE INVENTION

One aspect of the invention provides a subsea capture system, comprising a plurality of leak sources on a sea floor, the leak sources having a density less than sea water; and a plurality of capture devices located above the plurality of leak sources, the capture devices comprising a funnel shape comprising a large bottom opening inlet and tapering to a small top opening outlet.

Another aspect of the invention provides a method of capturing subsea leaks, comprising locating a plurality of leak sources on a sea floor, the leak sources having a density less than sea water; installing a capture device above each of the plurality of leak sources, the capture device comprising an opening at a bottom of the capture device to receive the leak source within the capture device; and collecting the leak source at one or more collection points located at a top of the capture device.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the features and advantages of the present invention can be understood in detail, a more particular description of the invention may be had by reference to the embodiments thereof that are illustrated in the appended drawings. These drawings are used to illustrate only typical embodiments of this invention, and are not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale or in schematic in the interest of clarity and conciseness.

FIG. 1 is a schematic diagram depicting a wellsite positioned above a subsea reservoir, the wellsite having a containment system with free-standing collectors in accordance with an aspect of the present invention.

FIGS. 2A-2B are schematic diagrams depicting a wellsite positioned above a subsea reservoir, the wellsite having a containment system with anchored collectors in accordance with an aspect of the present invention.

FIG. 3 is a flow chart depicting a method of containment.

DETAILED DESCRIPTION

Some embodiments of the invention are shown in the above-identified figures and described in detail below. Embodiments are described with reference to certain features and techniques for containing fluids released into the sea.

FIG. 1:

FIG. 1 is a schematic diagram depicting a wellsite 100 positioned above a reservoir 102. The wellsite 100 may be provided with a containment system 103 for capturing fluids released or spilled into the sea 106. The wellsite 100 may have a surface system 104 floating on the sea 106, and a subsea system 105 therebelow. The subsea system 105 may recover fluids from the reservoir 102, and pass such fluids to the surface system 104.

The surface system 104 may be provided for collecting, distributing and/or processing the fluids retrieved from the subsea system 105 and/or the reservoir 102. A riser 108 may extend below the surface system 104 to a location proximate a sea floor (or mud line) 110. As shown in FIG. 1, a subsea end of the riser 108 may be secured to a suction pile 111 positioned in the sea floor (or mud line) 110. A riser connector 109 may be provided to secure the riser 108 in position. In some cases, the subsea end of the riser 108 may be positioned about the subsea system 105 for receiving fluid therefrom, as will be described more fully herein.

The subsea system 105 may have one or more blow-out preventers (BOP) 112 positioned at a top end of one or more wellbores 114. The wellbore 114 may extend through the sea floor 110 and into the reservoir 102. The BOP 112 may be in fluid communication with the wellbore 114 for receiving the fluids (e.g., gas, hydrocarbons, water, etc.) from the reservoir 102. A manifold 116 may be fluidly connected between the BOP 112 and the riser 108 to facilitate and/or manipulate the flow of fluids therebetween.

The riser 108 may receive fluids generated from the reservoir 102. The riser 108 may be, for example, a tubular member for passing fluid received from the BOP 112 and/or manifold 116 to the surface system 104. A trap 117 may be provided at the subsea end of the riser 108 to collect fluids and/or solids. A pump 118 may be provided within the riser 108 to selectively draw fluid from the BOP 112 and into the riser 108.

Fluid may be passed from the riser 108 to the surface system 104. The surface system 104 may have a surface collector 122 for receiving the fluids. The surface collector 122 may be any suitable system for collecting, storing, separating, and/or transporting the collected fluids. The surface collector 122 may be, for example, a separator that separates the collected fluid into components, such as gas, water, liquid hydrocarbons and the like. The surface collector 122 may also be a conventional collector capable of storing fluid at or near the surface.

The components of the fluid stored in the surface collector 122 may optionally be removed, for example, by burning gas with a flare 124, by transporting liquids to a vessel 120 via tubing (or off-take line) 126 and the like. The tubing 126 may be used to fluidly connect the surface collector 122 to the vessel 120. One or more surface collectors 122, risers 108, vessels 120 and tubings 126 may be provided.

In some embodiments, suitable collection funnels, risers, and separators that may be used with the invention are disclosed in co-pending U.S. provisional patent applications 61/376,534, having attorney docket number TH4086; 61/376,542 having attorney docket number TH4085; 61/376,595 having attorney docket number TH4088, which are all herein incorporated by reference in their entirety.

From time to time, fluid from the reservoir 102 or a section of the wellbores 114 may escape into the sea 106. For example a wellsite leak 130A from a wellbore 114A,B and/or from a BOP 112 may allow fluid to escape from the subsea system 105 and into the sea 106 as fluid is produced from the reservoir 102. Further, a reservoir leak 130B, for example fluids seeping through cracks or fissures in the sea floor 110, may allow fluid to escape directly from the reservoir 102 or a section of the well 114, through the sea floor 110 and into the sea 106. The containment system 103 may be employed to recapture fluid released by one or more wellsite/reservoir leaks 130A and/or 130B. The containment system 103 is preferably a mobile system that may be transported to the wellsite 100, and deployed into position to capture fluid from the wellsite/reservoir leaks 130A and/or 130B.

The containment system 103 may have one or more subsea (or leak) collectors 132 and one or more flow lines 134. One or more subsea collectors 132 may be positioned a distance above the wellsite/reservoir leaks 130A and/or 130B to collect fluids therefrom. The collected fluid may travel from the subsea collector 132 to the surface collector 122 via the flow lines 134. The flow lines may be fluidly connected directly to the surface collector 122 and/or connected to the riser 108 for the fluids to flow to the surface collector 122 as shown in FIG. 1.

FIGS. 2A & 2B:

FIGS. 2A and 2B are schematic diagrams depicting various configurations of a containment system 203 in operation at the wellsite 200. The wellsite 200 has multiple wellbores 114A and 114B coupled to the BOPs 112A, 112B (shown schematically) for producing the reservoir 102. Each of the BOPs 112A, 112B may have produced a wellsite leak 130A. A reservoir leak 130B may also have been produced from the reservoir 102 and through the sea floor 110. The wellbores 114A,B, BOPs 112A,B, reservoir 102, sea floor 110 and wellsite/reservoir leaks 130A,B may be the same as those described with respect to FIG. 1, except that multiple wellsites 114A,B and BOPs 112A,B are provided.

The containment system 203 includes a surface system 204 and a subsea system 205, similar to those of FIG. 1, except that fluid from the wellsite/reservoir leaks 130A,B are transferred from subsea collectors 232 and to a riser 208a by flow lines 134. Like the containment system 103 of FIG. 1, fluid captured from the wellsite/reservoir leaks 130A,B may be passed to a conventional surface collector 122 for storage, separation and/or processing. The collected fluid may optionally be passed to a vessel, such as vessel 120 of FIG. 1, for storage and/or transport.

As shown in FIGS. 2A & 2B, the subsea collectors 132 are free-standing, or unsecured at a lower end thereof. Alternatively, collectors 132 may be sealed and/or anchored to the BOP 112, or alternatively anchored to the sea floor 110 such as with clump weights or driven or suction piles.

In the configuration of FIG. 2A, all of the subsea collectors 232 are fluidly connected to a riser 208a by the flow lines 134. The subsea collectors 232 of FIG. 2A may be the same as the subsea collectors 132 of FIG. 1. As shown in the Figure the subsea collectors 232 are anchored to the subsea floor 110. These anchored subsea collector(s) 232 may be any suitable device for capturing fluid from the wellsite/reservoir leaks 130A and/or 130B. The subsea collectors 232 may be specifically designed and deployed for collecting fluid from a variety of wellsite/reservoir leaks 130A and/or 130B.

As shown in FIG. 2A, the subsea collector 232 may include a non-sealed open funnel (or water cap) 210 allowing free passage of fluid therein. The funnels 210 each have an open bottom 212, a cylindrical body 213, a tapered top 214, and an exit end 215 configured to facilitate upward movement of the fluid into the flow lines 134. The open bottom 212 may be large enough to capture, and/or enclose the fluids escaping from one or more wellsite/reservoir leaks 130A and/or 130B. The exit end 215 of the funnel 210 may couple to the flow lines 134, using any suitable method. The funnel 210 may be constructed of any suitable material such as metal, plastic, fabric, elastomer, a combination thereof, and the like.

In other embodiments, the subsea collector 232 may include a sealed funnel or flange connected directly to a BOP, or sealed around the perimeter of a well or a leak, for example with an annular suction pile.

As shown in FIG. 2A, the funnel 210 may be secured to the subsea floor by one or more clump weights (or anchors) 220 coupled to the funnel 210 by one or more tethers 222. While the configurations of FIGS. 1 and 2A-2B depict a subsea collector 232 having an open bottom 212 positioned a distance above a wellsite/reservoir leak 130A,B, the subsea collector 232 may be positioned over wellsite equipment, such as the BOPs 112A and/or 112B, to create a seal thereon and draw fluid therefrom. In another example, the funnels 210 may be forced into the mud or sea floor 110 to create a seal therein, and to prevent release of fluid into the sea 106, or directly connected to an annular pile to create a seal around the BOPs or leak sources.

The exit end 215 at the top of each of the subsea collector 232 is depicted in FIG. 2A as being connected to corresponding flow lines 134. A valve 226 is optionally provided between the subsea collectors 232 and the flow lines 134 to control the flow of the fluids from the subsea collectors 232 and into the flow lines 134. The flow lines 134 may be angled up from the subsea collectors 232, and toward the surface to define an upward path for the flow of fluid therethrough. The flow lines 134 may be any suitable flow path for allowing fluids to travel from the subsea collectors 232 to the riser 208a, and for supporting the subsea collectors 232 in position about the wellsite/reservoir leaks 130A and/or 130B. For example, the flow lines 134 may be a flex hose, a plurality of pipes, a tubing, a canvass tube, a fabric tube, a metal tube, a composite tube, a plastic tube, a combination thereof, and the like. Supports (not shown), such as buoys, may optionally be provided to support the subsea collectors.

The flow lines 134 may be assembled before, during and/or after deployment of the containment system 203 to the wellsite 200. The flow lines 134 and the subsea collector 232 may be deployed into position by an ROV, a diver, a submarine and/or other means (not shown). The flow lines 134 may further include any number of components, such as flanges, blinds, storage spools, connectors and the like, configured to facilitate the routing, flexibility, operation, and/or transport of the riser 208a and/or flow lines 134.

In an example where the flow lines 134 are flexible lines, such as flex hose, flexible tubing, and/or tubing, the flow lines 134 may be stored proximate the riser 208a during transport, and extended into position for operation when desired. In an example where the flow lines 134 are hard pipes, the riser 203 may be provided with pre-drilled holes and/or connectors, such as connector 221, for receiving the flow lines 134. The riser 203 may also be pre-assembled and/or permanently piped with the flow lines 134 prior to installation. Any suitable method may be used to couple the flow lines 134 to the riser 208a, such as connectors, adhesives, bonds, welds and the like.

A surface end 202 of each of the flow lines 134 may be fluidly coupled to the riser 208a as shown in FIG. 2A, or positioned inside riser 208b as shown in FIG. 2B. The riser 208a may be a conventional riser for passing fluid to the surface collector 122. The riser 208a may be adapted to receive the flow lines 134, for example from about 2 to about 10 or more, such as 3 to 6 flow lines. Optionally, the riser 208a may be provided with openings, pipings, flanges or other features at various depths to facilitate receipt of the flow lines 134. Such features may facilitate the pre-assembly and/or installation of the containment system 203 at the wellsite 200. The riser 203 may also be provided with valves, pumps or other devices (not shown) to manipulate the flow of fluid therethrough. For example, the riser 208 may have a valve (not shown) that may be activated to initiate the flow of fluid therethrough.

In the configuration of FIG. 2B, the containment system 203 has a modified riser 208b. The riser 208b of FIG. 2B may have an open bottom 242 for receiving the upper end 202 of the flow lines 134. The flow lines 134 may be fluidly coupled to the riser 208b by placing the flow lines 134 into the open bottom 242 of the riser 208b. Any suitable method may be used to secure the flow lines 134 within the open bottom 242 of the modified riser 208b such as using connectors, adhesives, bonds, welds and the like.

FIGS. 1, 2A-2B depict specific configurations of containment systems 103, 203. However, various combinations of the features described may be provided. For example, the wellsites may be provided with one or more wellsite/reservoir leaks 130A, 130B and/or containment systems 103,203, BOPs 112A, 112B, manifolds 116, and/or other features as shown. One or more valves (e.g., 226) may be positioned about the containment system 203 to control the flow of the fluids captured by the subsea collector 232. The one or more valves may be any suitable valves or combination thereof for selectively controlling flow and/or pressure in the containment system, such as control valves, gate valves, check valves, and the like. For example, valve 226 may be a check valve configured to allow one way flow from the subsea collector 232 to the surface collector 122.

The subsea collector 232, riser 208a,b and/or flow lines 134 may have other devices for enhancing the operation thereof, such as one or more collector valves 218 to control fluid flow, one or more pumps 223 to facilitate movement of the fluid, one or more gauges 224 to take subsea measurements (e.g., temperature, pressure, flow rate, etc.), a manifold (e.g., 116 of FIG. 1) to manipulate fluid flow, and the like. Buoys and/or weights (not shown) may also be positioned about components of the wellsite, such as the flow lines 134, risers 208a,b and/or subsea collectors 232, to control the location thereof.

FIG. 3:

FIG. 3 is a flow chart depicting a method 303 of containing one or more leaks (e.g., wellsite/reservoir leaks 130A,B). The method involves positioning (350) a containment system (e.g., 103, 203) about a leak at a wellsite (e.g., 100, 200). The step of positioning may involve, for example, deploying (352) a surface collector (e.g., 122) to the wellsite, positioning (354) at least one subsea collector (e.g., 132, 232) of the containment system over the leak, for example 2 or more, positioning (356) a riser (e.g., 108, 208a,b) in fluid communication with the surface collector, fluidly connecting (358) the subsea collector(s) and the riser via at least one flow line (e.g., 134).

The method 303 further involves passing (360) fluid from the leak to the surface collector via the containment system. The fluid may then be separated (362) in the surface collector, and passed (364) from the surface collector to a vessel. These steps may be performed in any order, and repeated as desired.

It will be understood from the foregoing description that various modifications and changes may be made in the preferred and alternative embodiments of the present invention without departing from its true spirit. For example, one or more flow lines 134 may be used to fluidly connect one or more subsea collectors (e.g., 132, 232) to one or more risers (e.g., 108, 208a,b), surface collectors (e.g., 122) and/or other devices (e.g., vessel 120) for passing fluid thereto. The containment systems 103, 203 described herein may be free standing as shown in FIG. 1, or anchored to the sea floor as shown in FIGS. 2A and 2B.

Illustrative Embodiments

In one embodiment, there is disclosed a subsea capture system, comprising a plurality of leak sources on a sea floor, the leak sources having a density less than sea water; and a plurality of capture devices located above the plurality of leak sources, the capture devices comprising a funnel shape comprising a large bottom opening inlet and tapering to a small top opening outlet. In some embodiments, the leak sources comprise oil. In some embodiments, the leak sources comprise natural gas. In some embodiments, each of the capture devices is connected to a flow line. In some embodiments, each of the capture devices is connected to a flow line, and each of the flow lines are connected to a riser. In some embodiments, the plurality of leak sources comprise from about 3 to about 10 leak sources. In some embodiments, the capture device comprises a major dimension across a base of the device from about 0.5 meters to about 10 meters. In some embodiments, the capture device comprises a diameter across a base of the device from about 1 meters to about 5 meters. In some embodiments, the capture device comprises a flexible sheet material. In some embodiments, at least one capture device is fluidly sealed to a blow out preventer. In some embodiments, the system also includes a separator fluidly connected to the capture devices. In some embodiments, the system also includes a liquid storage vessel fluidly connected to the capture devices.

In one embodiment, there is disclosed a method of capturing subsea leaks, comprising locating a plurality of leak sources on a sea floor, the leak sources having a density less than sea water; installing a capture device above each of the plurality of leak sources, the capture device comprising an opening at a bottom of the capture device to receive the leak source within the capture device; and collecting the leak source at a more collection points located at a top of the capture device.

This description is intended for purposes of illustration only and should not be construed in a limiting sense. The scope of this invention should be determined only by the language of the claims that follow. The term “comprising” within the claims is intended to mean “including at least” such that the recited listing of elements in a claim are an open group. “A,” “an” and other singular terms are intended to include the plural forms thereof unless specifically excluded.

Claims

1. A subsea capture system, comprising: a plurality of leak sources on a sea floor, the leak source fluids having a density less than sea water; anda plurality of capture devices located above the plurality of leak sources, the capture devices comprising a funnel shape comprising a large bottom opening inlet and tapering to a small top opening outlet.

2. The system of claim 1, wherein the leak sources comprise oil.

3. The system of claim 1, wherein the leak sources comprise natural gas.

4. The system of claim 1, wherein the leak sources comprise fluid from a hydrocarbon reservoir.

5. The system of claim 1, wherein each of the capture devices is connected to a flow line.

6. The system of claim 1, wherein each of the capture devices is connected to a flow line, and each of the flow lines are connected to a riser.

7. The system of claim 1, wherein the plurality of leak sources comprise from about 3 to about 10 leak sources.

8. The system of claim 1, wherein the capture device comprises a major dimension across a base of the device from about 0.5 meters to about 10 meters.

9. The system of claim 1, wherein the capture device comprises a diameter across a base of the device from about 1 meters to about 5 meters.

10. The system of claim 1, wherein the capture device comprises a flexible sheet material.

11. The system of claim 1, wherein at least one capture device is fluidly sealed or partially sealed to enclose a leak source.

12. The system of claim 1, wherein at least one capture device is fluidly sealed to a blow out preventer.

13. The system of claim 1, further comprising a separator fluidly connected to the capture devices.

14. The system of claim 1, further comprising a liquid storage vessel fluidly connected to the capture devices.

15. A method of capturing subsea leaks, comprising: locating a plurality of leak sources on a sea floor, the leak source fluids having a density less than sea water;installing capture devices above the plurality of leak sources, the capture devices comprising an opening at a bottom of the capture device to receive the leak source within the capture device; andcollecting the leak source at one or more collection points located at a top of the capture devices.