CA2809627A1 - Textile oil containment sleeve - Google Patents

Description

TOCS ¨ Textile Oil Containment Sleeve Background of the disclosure The present disclosure relates to a system that will contain the oil or any other lighter than water effluent leaking from a subsea oil well, pipeline or submerged vessel.
The system in its simplest form consists of a fabric sleeve that is equipped with a buoyant upper segment and a weighted lower section, that can be positioned above a subsea leak of oil or other buoyant effluent and used to contain and transport the oil, gas and other buoyant effluent to the surface, where it can be removed by attending vessels.
The system uses the simple principles of the relative buoyancy between oil (or other effluents) and water, the equalization of pressure between an open bottom contained column of oil (or other lighter than water effluent) and the surrounding water column at the bottom of the containment structure, and the relative greater height of the column of oil in relation to the water column, required to achieve the equalized pressure.
By using the principle of buoyancy of the oil in water, combined with the relatively large diameter of the sleeve, allows the bottom of the sleeve to be positioned at some distance above the leak source, thereby not requiring any complex clamping or sealing device to mate with the wellhead, pipeline or submerged vessel, in order to capture the effluent.
In addition, the principles of buoyancy of air or gas filled chambers relative to the water and the effect of differential pressure inside a torroidal fabric ring to maintain the shape of the toroid, is utilized.
The principle of the differential fluid pressure between the toroid chambers and the surrounding water environment is used to maintain the shape of the toroid.
These principles are applied to a fabric sleeve apparatus that will, by virtue of the pressure inside the sleeve and the pressurized torroidal rings, maintain the shape of the sleeve in an ocean environment. The sleeve creates a conduit to contain and direct the effluent to the surface, within the confines of the sleeve, where the oil can be removed from the sleeve and stored in suitable vessels.
The fabric sleeve, as opposed to existing steel structures developed to contain oil well blowout spills, is inherently lightweight, easily stored in a shipping container, can contain very large volumes of oil within a very light structure and is easily deployed from readily available vessels, such as offshore supply and anchor handling vessels. It does not require any heavy lift or large size transport vessels and can be deployed prior to the drilling of the well as a contingency procedure.
These qualities, and the use of basic principles of physics, overcome the issues related to the time required to mobilize and install the existing 'top hat' type blowout containment structures, limit the amount of oil that will be discharged to surface and spread as an uncontrollable large area oil slick, to a minor fraction of that which would be discharged in the above mentioned mobilization time frame. The compact size would allow almost any standard supply/standby vessel to carry one or more of these as deck cargo when attending a drilling operation, which allows almost immediate response to a blowout - incident.
TOCS Mar 7.2 Page 1 of 14 This disclosure, as a method to contain and control the effluent spread, to provide the ability to simply remove the captured oil and provide the ability to use standard equipment to deploy the equipment, is considered to be unique.
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Detailed Description of the Disclosure ¨ Textile Oil Containment Sleeve TOCS refers to a Textile Oil Containment Sleeve which is used to capture and contain the oil and/or gas effluent (6) released from a subsea blowout or other source effluent, separate the gas from the effluent flow and, bring the effluent to surface where it can be pumped from the containment area created by the buoyant upper portion (3), to storage vessels. The gas is naturally vented to atmosphere.
The present disclosure relates to an apparatus, an extendible effluent containment sleeve, to contain the effluent from a below water leak source (pipeline, sunken vessel or oil/gas well) to confine the effluent to a relatively small volume during the transit from the sub sea leak source to, and once it reaches, the water surface. The sleeve can be deployed either a collapsed or extended state prior to any oil well to be drilled, as a contingency precaution, so any blowout can be immediately contained. The apparatus can also be delivered and deployed quickly in response to a leak from an oil well or pipeline or a sunken vessel. In addition, the disclosure provides a means to contain the effluent into a small area once it reaches the water surface, to allow it to be removed by simple means (hose connection) to be pumped into storage/processing facilities. Containing the spread of the oil into a small area, as opposed to the square miles of ocean that have been affected by oil slicks from all offshore blowouts and other leaks to date, greatly reduces the environmental impact of the spill. It also reduces the need for many complex and large specialized vessels to collect the oil. Conventional and readily available vessels can be used to pump out the contained oil out of the sleeve and into their storage tanks.
The sleeve rapidly provides a large volume for storage of effluent, and thus provides time for support vessels to be mobilized for the safe removal of the oil or other effluent.
The large diameter of the sleeves illustrated in Figure 1 and Figure 2 precludes the gas hydrate problem seen during the Macondo blowout. In that incident, gas hydrates blocked the oil extraction line which led from the steel device deployed to contain the blowout effluent.
The sleeve apparatus will be filled with the effluent by the principle of the buoyancy of the effluent in water, which will cause the effluent to fill the containment sleeve by displacement of the water inside the sleeve. The sleeve apparatus becomes pressurized by the static head of effluent that accumulates within the sleeve and fills the above water line containment area. This basic principle, in conjunction with the design of pressurized torroidal bladders (2) integral to the sleeve, will maintain the sleeve shape, once deployed. The flexible nature of the apparatus allows it to be easily transported to site and deployed either prior to the drilling of a subsea oil/gas well, or in response to a leak from a subsea oil/gas well, pipeline or sunken vessel.
The gas that can be associated with a blowout will naturally vent from the effluent once it reaches the surface within the containment sleeve.
The Macondo blowout in the Gulf of Mexico has heightened concern over the consequences of an unconstrained leak from an oil well. Sensitive areas in the Gulf of Mexico, the Arctic and other areas of the world, such as prime fishing areas, are areas of great concern with respect to pollution from an oil well blowout, a pipeline, or damaged sunken tanker or other vessel.
The oil industry has developed large, heavy 'top hat' structures that require significant time and resources to move to a blowout site. This delay in deployment will potentially allow very large quantities of oil to TOCS Mar 7.2 Page 3 of 14 =
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be discharged to the environment in the interim between when the blowout occurs, and when the 'top hat' type structures are finally deployed and in place. The top hat devices are also, relative to the large diameters to which the TOCS can be fabricated, quite small, and as such require a much greater degree of positioning accuracy to cover the leak source. The sleeve apparatus is easily and quickly transported by a standard offshore supply vessel, and can be deployed using standard offshore supply vessels, without the need for specialized or large deployment vessels that were required to lift and position the heavy steel containment domes.
The process of containing the oil within the sleeve will not only protect the environment but will keep the oil available for subsequent transport to facilities that can process and dispose, or market, the recovered oil.
Figures 1 and 2 TOCS consists of a sleeve (1) of textile, treated as required to contain the effluent. The sleeve extends from a depth below the sea surface, to a height above the sea surface. The dimensions for the below and above water line sleeve segments are dependant upon the water depth and the volume of oil to be contained within the sleeve. The sleeve is open at both ends with its longitudinal axis in a vertical orientation. The sleeve is kept from collapsing radially on itself by a plurality of firm toroidal bladders (2) installed at intervals along the length of the sleeve. The torroidal bladders (2) and/or (3) and/or (4) may be made up of a plurality of torroidal ring segments connected together, or a plurality of vertical chambers connected together. The firmness of the bladders is determined by the pressure of the fluid with which they are filled. The topmost one or more toroids (3) may be filled with a compressed gas or air to provide buoyancy and the lowermost toroids (4) may be filled with a heavy liquid, such as a weighted drilling fluid, to provide ballast. Alternatively or additionally, weights may be attached to the lower portion of the sleeve as ballast. The differential force, resulting from the buoyant force at the top part of the sleeve and the weight of the ballast at the bottom, is used to keep the sleeve from collapsing longitudinally. Toroid ring chambers (2) along the length of the sleeve installed to provide stiffness, but are not required for buoyancy or ballast, are filled with neutal density fluid, most commonly water.. The torroidal rings may be filled with a buoyant fluid or air/gas in the event that additional buoyancy is required.
In its simplest form, the top portion (3) of the TOCS extends above the sea surface and thus creates a containment 'pool' for the effluent. The ballasted base of the TOCS (4) may either be deployed to rest on the sea floor or it may remain suspended some distance above the sea floor by the buoyant force of the upper sections. Keeping the base of the TOCS off the seafloor would facilitate access to the BOP or source of the leak, should this be required.
The base of the TOCS is preferentially kept above the sea floor in order to ensure that water can freely flow into and out of the sleeve, as required by the filling of the sleeve with effluent, and subsequent operations to remove the effluent from the sleeve, as well as to allow access to the effluent source as required by divers or underwater vehicles.
The base of the TOCS is retained in position by wires, ropes or chains or a combination of these, running from the anchor points on the TOCS to anchors or anchoring devices on the seafloor. In applications TOCS Mar 7.2 Page 4 of 14 where required, heavy ballast can be added to the lower toroids in order to keep the base in position on the seafloor or in position on a sunken vessel or pipeline.
The top portion of the TOCS (3) is open to the atmosphere, thus facilitating the venting of any gas that has been released in the effivant plume.
The portion of the TOCS (3) that is above the sea surface and extends down below the still water line to a depth equivalent to the height above sea level, to account for intermittent exposure due to wave action, is fire resistant or covered with a fire resistant material.
The top portion (3) of the TOCS may be a plurality of multiple chamber torroidal rings, or may be a plurality of vertical chambers.
The volume enclosed by the TOCS can be varied to match different conditions of water depths, and anticipated effluent flow rates, by changing the manufactured dimensions of the TOCS.
The height of the above sea surface portion (3) of the TOCS is designed to be adequate to provide the required hydrostatic head to retain the required volume of effluent within the TOCS sleeve and to keep the retained effluent from spilling over the top as a result of the buoyancy of the submerged portion of effluent and as a result of any wave action on the sleeve at the surface.
The TOCS may comprise of different fabrics, and thicknesses of fabric to have sufficient strength or properties to contain the effluent, provide sufficient strength to react to anchoring, buoyancy, ballast and locating forces and provide fire resistance where necessary.
The top portion (3) of the TOCS may be outfitted with a plurality of self-sealing ports (5) that will allow a hose with a 'stinger' attachment to be inserted in through the sidewall of the sleeve to allow effluent to be withdrawn from inside the TOCS and pumped to a suitable storage vessel or device.
In its simplest form, the TOCS has a circular cross section. For some applications, such as high current or ice conditions, an alternate shape such as an ellipse may be preferable for one or more portions of the TOCS.
In its simplest form, the diameter of the TOCS is uniform throughout its entire length. For some applications, the design diameter of the TOCS will vary along its length.
In its simplest form, TOCS consists of one structure which has a base of sufficient diameter to capture the effluent plume that is rising from the damaged wellhead or leak source. The large storage volume created by the TOCS will be designed to contain the effluent for a period of time at a design flow rate, thus capturing the oil that would be otherwise be escaping into the environment.
The TOCS contains the oil for as long as required until it can be pumped into storage vessels or other containment devices In some applications, such as very deep water depths and/or high current conditions, two TOCS can be used in conjunction with each other. Each of the two units has a different function and shape but each unit utilizes the same principles of firm bladders to provide radial structural stability and differential buoyancy and ballasting to provide tension along their length. The shape and function of each of the two is as follows:
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1. Fig 2 In a two-unit arrangement, the lower TOCS apparatus is used to capture the effluent and to direct it toward the inside of the upper TOCS in a controlled manner. The lower portion of the lower TOCS may be a truncated cone (7) as shown or may be cylindrical, depending on the application. The base of the lower TOCS has an opening that is large enough to capture the effluent stream and may also contain the wellhead or Blow Out Preventor (BOP), or other effluent source, depending on the leak source location, and thus prevent the effluent from spreading laterally as it begins to drift upward due to its buoyancy. The upper portion of the lower TOCS forms a vertical tubular section (8) which acts like a chimney, allowing the effluent to continue its drift upward in a controlled manner. In some applications, the effluent leaves the open top of the sleeve (8) at the sea surface. In other applications, it may be preferable to release the effluent at some distance below the sea surface but inside the upper TOCS.
The lower portion of a two-unit arrangement is maintained in position over the wellhead through the use of anchor lines to the sea floor anchoring system. The base of the lower TOCS is kept above the sea floor in order to ensure that water can freely flow into and out of the sleeve as required by the filling of the sleeve with effluent, and subsequent operations to remove the effluent from the sleeve, as well as to allow access to the effluent source as required by divers or underwater vehicles.
2. In a two-unit arrangement, the upper TOCS is used to contain all of the effluent that has been delivered to the surface by the lower TOCS, as described above. The outlet of the lower TOCS
can be tethered with radial lines to the circumference of the upper TOCS in order to keep the outlet of the lower TOCS centred within the upper TOCS, by a plurality of straps, wires or ropes.
Each of the two TOCS of the two-unit arrangement described above can also be utilized independently.
Fig 3 is an illustration one of an example application, the lower TOCS can be used to deliver the effluent stream directly to an alternate effluent management facility, such as a recovery vessel. In another example, the upper TOCS of a two-unit arrangement could be used alone where the length and diameter of the TOCS would be sufficient to capture the effluent and the lower unit would not be required.
The TOCS can be used fully deployed as a contingency device during some operations, stored in a collapsed state at an offshore oil well drilling well site, prior to the commencement of drilling operations, stored in a semi deployed state adjacent to the drilling site, or it can be delivered and deployed at location once an incident has occurred.
When stored in a collapsed state on the sea floor around the BOP, the bladders providing ballast (4) and radial structural integrity (2) are filled prior to deployment. When deployment is required, the floatation bladders (3) are inflated, usually using attached compressed air or gas cylinders or compressed air from a surface vessel. Only partial inflation is required to cause the TOCS to extend upward. As the inflated chambers rise in the water column, their expansion provides additional floatation. Pressure relief valves in the chambers ensure that their pressure remains within the required and acceptable structural limits of the chambers. As the upper portion of the TOCS approaches the surface of the water, it lifts the ballasted base (4) from the seafloor and the base is retained in place by the tension in the attached anchor lines.
Alternatively, the TOCS can be positioned in a collapsed or semi collapsed configuration adjacent to the well centre as described above, and then fully deployed so that the lower portion of the TOCS is suspended 'at an elevation that is higher than the effluent source. The TOCS
is then repositioned laterally -TOCS Mar 7.2 Page 6 of 14 over the source with tow lines from surface vessels and/or subsea (ROY) type units before it is attached or re-attached to the anchors on the sea floor.
When delivered to location in response to an ongoing incident, the TOCS is lowered into the water in a collapsed state either directly over the blowout or leak, or adjacent to the blowout site, depending on the surface location of the gas and effluent plume. The floatation (3) and structural bladders (2) are then filled in order to allow the TOCS to expand into a ring shape. A weighted fluid, such as drilling mud, can be pumped into the lower ballast bladders (4) in order to expand the ring into a cylindrical shape that extends around the leak source and to provide ballast weight for the TOCS.
Alternately, weights or additional bladders filled with weighted material such as barite, metal pellets or other granular material can be attached to the lower portion of the TOCS in order to provide ballast or extra ballast, as required by the operation. The deployed TOCS is manoeuvred into position over the leak source and the anchor lines are then attached.
The effluent accumulated in the TOCS can be pumped away into tankers or other vessel suitable to store the effluent, through the use of flexible hoses. Hoses to remove the effluent from the effluent pool contained within the TOCS, can be positioned over the TOCS structure to ensure the containment sidewall is not partially or fully collapsed at any point, minimizing any effluent escaping from the TOCS.
Alternatively, the tanker hoses can enter the effluent pool using stingers (hose extension assembly) as part of a floating hose assembly that allows the hose to be stabbed into and mate with self-sealing openings in the side of the TOCS.
Fig 3 shows the TOCS can be installed from a barge or ship equipped with a moonpool or open area under a deployment deck (in the case of a multi-hull vessel), and deployed from those vessels. The TOCS
would be connected to the vessel which would allow for position control of the TOCS. The vessel can be outfitted with tanks directly connected to the moonpool area to allow the effluent to decant directly into the tanks. Alternatively, pumping systems and tanks could be built into the vessel to remove the accumulated oil from the TOCS and/or the moonpool area and pump it into tanks on the vessel, or pump to other vessels as the oil accumulates in the TOCS and/or moonpool.
TOCS Mar 7.2 Page 7 of 14 Prior Patent references TOCS Mar 7.2 Page 11 of 14

Claims (39)

1. An assembly which consists of a vertical Textile Oil Containment Sleeve (TOCS) that may be impermeable, or where required, coated to be considered impermeable to collect and control the dispersion of oil or other lighter-than-water effluents being released below the sea surface.

2. The sleeve is designed to capture the entire effluent plume near the point of release before the plume has had a chance to spread laterally outside the area constrained by the TOCS sleeve.

3. The sleeve is designed to allow buoyant effluents to rise toward the sea surface in a contained manner and without a requirement for pumping.

4. The sleeve is designed to facilitate the release and natural dispersion of any gasses entrained in the effluent.

5. The cross sectional shape of the sleeve in plan view is established and maintained through the use of a plurality of fluid filled pressured bladders

6. The pressure bladder assembly consists of a plurality of independent bladders that will maintain the cross sectional shape in plan view even if a number of the pressure bladders are damaged

7. The sleeve is designed to accommodate the differences between the internal pressure created by the effluent displacing the water inside the sleeve , and the external pressure, both below and above the sea surface.

8. The sleeve is designed to use the difference between the internal pressure gradient of the buoyant liquid effluent to displace the water, and the external pressure gradient of the water to maintain the shape of the sleeve in the areas between the inflated pressure bladders.

9. The sleeve is most commonly circular in plan view cross section, but other plan view cross section shapes may be utilized if required.

10. The uppermost section of the sleeve is outfitted with a plurality of buoyancy chambers, which may be circular toroids, segments of toroids or vertically oriented bladders.

11. Where the sleeve is used at the sea surface, the buoyancy chambers in the uppermost section will create a containment that extends above the water surface and will allow the effluent to accumulate to a height above the waterline, which will create the pressure differential between the effluent inside the sleeve and the surrounding water as the effluent fills the sleeve.

12. The buoyancy chambers assembly will be constructed so that there are a plurality of independent chambers so that damage to any one or set of chambers will not prevent the sleeve from deployment and operation.

13. Where the sleeve is used at the sea surface, the buoyancy chambers may be connected with the sleeve fabric material to create a containment volume of the effluent that will be a height above sea level that will correspond to the height required to allow the design volume of effluent to be contained within the combined volume of the above and below water line sleeve.

14. The buoyancy chambers may be connected together in such a manner as to not require additional fabric between the chambers to create the above water line containment volume.

15. Where the sleeve extends above the sea surface, the uppermost containment section of the sleeve, which will be defined as that portion of the sleeve that extends above the still water line and to an equivalent depth below water line, that section has the ability to be equipped with a flame resistant covering, or fabricated from a flame resistant material, to allow the sleeve to function as a containment device in the event of the effluent or gasses associated with the effluent being on fire.

16. Where the sleeve extends above the sea surface, the uppermost containment section may be fitted with a flame resistant cover which has incorporated a vent hole to allow accumulated gasses to vent to atmosphere. The cover will prevent waves from overtopping the sidewall of the above waterline portion of the sleeve into the containment area, and define the area from which gasses will be escaping. The shape of the cover may be such that it will raise the vent point for the gasses above the level of the top of the containment area to a height that will enhance dispersion of the gasses and reduce the zones at sea level where gas may be of sufficient concentration to create a safety hazard.

17. The assembly can be used fully deployed as a contingency measure, or it may be deployed in a collapsed state on the seafloor prior to the drilling of any oil or gas well and, should the need arise, be deployed from the seafloor by inflating its buoyancy chambers.

18. The assembly can be deployed from a surface vessel after the occurrence of a leak or blowout incident.

19. The cross sectional area of the sleeve is determined according to the expected effluent flow rate, the volume of effluent to be contained and water depth in which it will be used.

20. The cross sectional area may vary along the length of the sleeve.

21. The length of the sleeve is determined according to the water depth in which it will be used.

22. Depending on the water depth, transportation or other issues, the sleeve may be made up of several cylindrical (or other shape if different from cylindrical) sections.
The sections may be connected together or they may be deployed in a tandem arrangement in which the sections operate in unison without actually being connected together.

23. Depending on transportation or assembly requirements (weight or assembly area constraints) each section may be made up of several longitudinal strips which can be connected together by a plurality of material straps or cables, to provide sufficient strength to allow the assembled sleeve to be deployed and operated.

24. The connection seam between any sections, longitudinal or horizontal, may be covered by means of overlapping panels held in place by a plurality of straps, cables, hook and loop sleeve sections.
The overlapping panels will reduce any potential leakage of effluent inside the sleeve to the water environment through the seams of the joined sections.

25. The sections will have a plurality of pressure bladders, buoyancy chambers and ballast chambers as appropriate to the installation and operation of the TOCS.

26. If the sections are connected, the connection will be by means of a plurality of tension devices (cables, straps or a combination of both) which are attached to the sleeve at locations deemed to be appropriate for the expected tensile loads.

27. There may be an overlap fabric panel between any two sections of the sleeve to contain the effluent with a minimum amount of leakage from the interface between the two sleeve sections.

28. The longitudinal extension of the sleeve is established and maintained through the appropriate use of a plurality of buoyancy and ballast chambers located at appropriate parts of the sleeve or sleeves.

29. The base of the sleeve is kept in position through the use of a plurality of anchors to the seafloor.

30. The top of the sleeve is kept in position by the buoyancy of its upper sections. The assistance of tugs or other external forces such as additional anchor systems, can be utilized if required.

31. In some applications, the apparatus will consist of only one appropriately designed unit to both capture and contain the released effluent.

32. In some applications, a two-unit variation may be utilized. In the two-unit arrangement, the capture of the effluent and its control as it rises to the surface is accomplished by one unit while the second unit contains the captured effluent, until it can be dealt with in an appropriate manner.

33. In the two-unit variation, either of the two units may be utilized alone if conditions are such that the other unit is not required.

34. The assembly enables off-pumping operations from the surface effluent pool through the use of hoses, flexible pipe or other means that can be inserted into the accumulated pool of effluent.

35. The assembly enables off-pumping operations from the surface effluent pool through the use of hoses, flexible pipe or other means that can be inserted through the sides of the assembly as a stab type 'effluent port' connection.

36. The effluent ports at the sides of the assembly are outfitted with a one way flap type check valve assembly to prevent unused ports from discharging effluent to the surrounding environment, but allows the hose 'stinger' to be inserted through the sidewall..

37. Multiple effluent removal ports around the perimeter of the containment will allow a plurality of surface vessels to connect to the TOCS to remove accumulated effluent

38. Multiple ports around the perimeter will allow effluent removal/storage vessels to be positioned upwind of the TOCS to avoid any gas plume that may be escaping from the effluent within the TOCS.

39. The TOCS system can be attached to and deployed from a barge, ship or multi-hull vessel outfitted with a moonpool which will allow effluent to be removed from the TOCS by decanting into vessel tanks or pumped from the moonpool area into vessel tanks or to other vessels.