Patent Application
20110299930
Not Applicable
1. Field of the Invention
The present invention relates to subsea oil leaks, and in particular relates to a subsea oil leak stabilization system (also referred to herein as SOLSS) and a method for developing and using a SOLSS.
2. Description of the Related Art
Water streams forced under pressure out a small diameter opening or nozzle (referred to herein as water-jetting or jetting) are used in the undersea construction industry and utilized for various tasks including dredging, fishing, trenching, cable burial and pipe-line burial. Jet-assistance in a plowshare or other trenching tools can significantly reduce the tow force (also referred to as draw-bar) required to successfully pull plows through an array of various sub-bottom soils in undersea cable burial operations. Water-jetting is also used by undersea Remotely Operated Vehicles (ROV) and bottom crawlers to unbury and rebury cables and pipelines during repair operations.
Water-jetting may be relatively simple and involve native materials, for example, the water source itself is readily available. Water jetting is an effective technique for fluidizing and cutting through both unconsolidated and consolidated ocean bottom soils. The force required to pull plowing and burial tools through seabed soils depends on soil dynamics and illustrates the effectiveness of seabed anchors.
The British Petroleum (BP) oil spill following the destruction of the Deepwater Horizon drilling platform in the Gulf of Mexico in 2010 involved an oil leak from a wellhead on the sea bottom, also referred to herein as the sea floor or the subsea surface. The wellhead included an oil riser pipe and a blowout preventer. The BP oil spill was not contained for several months causing significant environmental damage and imposing substantial monetary liabilities on BP.
A method for controlling a subsea leak from an opening in a pipe which extends from a subsea bottom surface is provided. The method uses an assembly including a manifold and an enclosing member extending above the manifold. The manifold includes a plurality of fluid outlets. The manifold and the enclosing member at least partially define an interior volume, a bottom having an opening adapted to accommodate the pipe, and a top outlet. The method includes opening the top outlet to allow a free flow of a fluid leaking from the pipe opening, and positioning the manifold to circumferentially enclose the pipe opening. The method also includes jetting fluid out of the plurality of outlets of the manifold toward the subsea bottom surface to remove subsea bottom material proximate the pipe after positioning the manifold, seat the bottom of the manifold into the subsea surface, and cause the manifold to move downwardly relative to the pipe opening. The method further includes injecting fluidized concrete into the interior volume above the subsea bottom surface to a level below the pipe opening to seal the bottom opening, and closing the top outlet above the subsea leak to seal the assembly.
The method may include positioning the manifold to circumferentially enclose the subsea leak before the jetting fluid operation. The subsea leak may originate from a riser pipe, and the riser pipe may be a vertical extension of a lateral pipe extending along the subsea bottom surface. The manifold and the enclosing member may have aligned cut-outs having a width greater than a diameter of the lateral pipe. The positioning of the manifold operation may include positioning the cut-out of the manifold over the lateral pipe. The method may include, before the injecting of the fluidized concrete into the interior volume, closing the aligned cut-outs of the manifold and the enclosing member
The method may include, after the jetting fluid operation, waiting to allow subsea bottom material to backfill around an exterior of the enclosing member before the injecting fluidized concrete operation. The method may include, after the jetting fluid operation, actively backfilling subsea bottom material around an exterior of the enclosing member before the injecting fluidized concrete operation.
The method may include, before the injecting fluidized concrete operation, weighting at least one of the manifold and the enclosing member to stabilize at least one of the manifold and the enclosing member.
The method may include, before the sealing operation, closing a valve above the subsea leak. The sealing operation may include capping the enclosing member above the valve.
The method may include, after the sealing operation, capping the enclosing member above a valve. The sealing operation may include closing the valve above the subsea leak.
The method may include, before the injecting fluidized concrete operation, removing at least some of the subsea bottom material from the interior of the enclosing member via outlets arranged on the enclosing member.
A device for controlling a subsea leak is provided that includes a manifold having a plurality of outlets. The manifold is adapted to jet water out of the plurality of outlets toward a subsea bottom surface to fluidize and displace subsea bottom material. The device also includes an enclosing member extending above the manifold and circumferentially enclosing the subsea leak. The enclosing member is adapted to receive fluidized concrete into an interior volume defined by the subsea bottom surface after removal of subsea bottom material and the enclosing member. The device further includes a seal at a top of the enclosing member above the subsea leak.
The manifold may be positioned by a lift cable and/or one or more remotely operated vehicles to circumferentially enclose the subsea leak. Aligned cut-outs of the manifold and the enclosing member may include closing doors.
The device may include stabilizing flanges arranged on an exterior of the enclosing member and adapted to stabilize the device in cooperation with subsea bottom material that backfills around an exterior of the enclosing member.
The device may include weights arranged to removably attach to at least one of the manifold and the enclosing member. The device may include a valve arranged in an interior of the enclosing member above the subsea leak and adapted to seal the enclosing member. The seal at a top of the enclosing member may be a cap situated above the valve.
The device may include a cap arranged on a top edge of the enclosing member above the subsea leak and adapted to seal the enclosing member. The seal at a top of the enclosing member may be a valve arranged in an interior of the enclosing member above the subsea leak.
The device may include outlets arranged on the enclosing member adapted to remove at least some of the subsea bottom material from the interior of the enclosing member before injecting fluidized concrete.
A system for controlling a subsea leak is provided that uses a manifold and an enclosing member extending above the manifold. The manifold includes a plurality of outlets directed toward a subsea bottom surface. The manifold and the enclosing member may define an interior volume and may be positioned so that the subsea leak is situated in the interior volume. The system includes means for jetting fluid out of the plurality of outlets of the manifold to fluidize and remove subsea bottom material, and means for injecting fluidized concrete into the interior volume above the subsea bottom surface after the jetting fluid operation. The system also includes means for capping the interior volume at a top of the enclosing member above the subsea leak.
The system may include means for actively backfilling subsea bottom material around an exterior of the enclosing member after jetting fluid and before injecting fluidized concrete, and means for weighting at least one of the manifold and the enclosing member to stabilize at least one of the manifold and the enclosing member before injecting fluidized concrete. The system may also include means for closing a valve above the subsea leak and below the top of the enclosing member before capping.
A method for controlling a subsea leak is provided using a manifold and an enclosing member extending above the manifold. The manifold includes a plurality of outlets directed toward a subsea bottom surface. The manifold and the enclosing member define an interior volume and are positioned so that the subsea leak is situated in the interior volume. The method includes jetting fluid out of the plurality of outlets of the manifold to fluidize and remove subsea bottom material, and injecting fluidized concrete into the interior volume above the subsea bottom surface after the jetting fluid operation. The method also includes sealing the interior volume at a top of the enclosing member above the subsea leak.
A quick response Subsea Oil Leak Stabilization System (SOLSS) is provided. The SOLSS approach defines a process for taking immediate emergency action for an oil leak, or other leaking pipe or riser. The system uses naturally occurring components of the environment, including water and soil, to contain and seal a faulted oil riser pipe.
The SOLSS uses water-jetting and in situ seabed materials to provide a stable permanent platform that has the potential for oil (or other leaking material) containment, and possibly subsequent access to the leaking material in a controlled manner. A SOLSS may include a large structure having modular components enabling assembly either dockside, onboard ship, or even underwater using standard construction techniques and standard shipboard handling equipment. All equipment and resources used with a SOLSS may be commercial available and obtainable with minimal effort for quick response to an emergency situation similar to the BP oil spill disaster.
The SOLSS uses a pipe, also referred to herein as a jetter pipe and alternatively any appropriate containing enclosure having an opening on a top and a bottom, and a pipe cap, also referred to herein as final pipe cap, to create a pressure vessel. A manifold, also referred to herein as a jetter manifold, high volume water pumps and suction equipment are also used, and may be the same or similar to these items as used in commercial equipment suites currently employed on cable plows, remotely operated vehicles, dredges and fishing trawlers. A motorized gate valve is also used and may be similar to those used on ocean bottom construction projects for the oil and gas industry. Fluidized concrete may be used and may be similar to the material used in ocean bottom structures in offshore drilling and construction.
Once assembled and deployed, a SOLSS may quickly and efficiently stop the flow of oil or other leaking material at the source, namely the riser pipe or other leaking pipe. The SOLSS may also create a stable bottom platform with a re-enterable final pipe cap enabling reopening and resumption of oil recovery, thereby avoiding abandonment and loss of the initial drilling assets.
These objects and the details of the invention will be apparent from the following description and accompanying drawings.
SOLSS may include a large-diameter jetter pipe outfitted with two large-diameter flanges, one at its midsection, referred to as the stabilizer flange, and another near the bottom, referred to as the anchoring flange. The anchoring flange may form the upper portion of a triangular cross section and circular shaped water jet manifold with downward facing jetter nozzles. The jetter pipe may also be outfitted with a circular array of high volume water pumps mounted around its circumference and above the stabilizer flange that feed a high volume of water to the water jet manifold. The jetter pipe assembly is also outfitted with a motorized gate valve for eventual shutdown of the oil flow. Additionally, the jetter pipe is outfitted with heavy lift-point weldments, access ports for other subsea connections and an arrangement of pin openings at the very top for the eventual remote installation and locking of a final cap.
Additional components of the SOLSS may include a set of reinforced concrete stabilization weights designed to fit over the jetter pipe to further stabilize the platform and resist the opposing force resulting from the oil exiting the riser pipe. The SOLSS is designed with modularity to accommodate over-the-road transportation and/or easy assembly at dockside, onboard the work deck of a recovery vessel, and/or undersea at the site. Ancillary equipment may include heavy cranes, a fluidized concrete provision, a composite umbilical/lift power cable, a soil suction (also referred to herein as a dredging) capability and one or more heavy-duty, work-class Remotely Operated Vehicles (ROV). Each ROV may be equipped with repair capability tools for marking, cutting, jetting and lifting/carrying some nominal payload.
Jetter manifold 110 may form an inverted triangle in cross-section, with externally directed surface 112 and internally directed surface 113 forming the two lower sides, while anchor flange 128 forms the third and upper side. These three sides may define chamber 114. Anchor flange 128 and internally directed surface 113 may join together at a point along with a lower edge of jetter pipe 130. Anchor flange 128 may be coupled to stabilizing flange 124 via flange support columns 126. Jetter pipe 130 may include ports 132 on an exterior providing access to interior 134 and which may be used for the suction or removal of material inside jetter pipe 130, for instance by flushing with seawater, also referred to herein as eduction. Additionally, ports 132 may be used for the injection of fluidized concrete 180 into interior 134 of jetter pipe 130 to form a plug and/or lower seal to jetter pipe 130 below a top edge of riser pipe 102.
After SOLSS 100 has been activated to remove subsea material below jetter manifold 110 through activation of jets 116 until stabilizing flange 124 is substantially even with the original subsea surface, or alternatively to a point that anchor flange 128 is considered to provide a sufficiently stable anchor for SOLSS 100, stabilization weights 140 may be positioned around jetter pipe 130 by lowering from above. The positioning of stabilization weights 140 may be accomplished using rigging from surface ships, ROVs or a combination thereof. Each stabilization weight 140 may include one or more weldments 142, which may be used for lifting and control. Stabilization weights 140 may be formed from reinforced concrete, and weldments 142 may include a loop of reinforcing steel that exits and reenters the concrete of stabilization weight 140. Stabilization weights 140 may include cut-outs to prevent interference with pumps 120, valve assembly 150, or any other element of SOLSS 100 or its auxiliary or ancillary equipment (see
Valve assembly 150 may operate to control valve 152. Valve assembly 150 may be a motorized gate valve assembly. Valve 152, which may be a gate valve, is shown in
Cap 160, also referred to herein as a final cap, is positioned on a top edge of jetter pipe 130 and secured to jetter pipe 130 using cap pins 164, which may be electrically, mechanically, or hydraulically operated remotely and/or secured using one or more ROVs. Cap 160 may include reentry ports 162, which may be used for oil recovery at a later time, and/or for the installation or removal of material and/or instruments. Cap 160 may be positioned using lifting lines 172, which may be controlled by a cap cable. The cap cable may in turn include an electrical umbilical for controlling cap pins 164, for collecting video or data, for subsea intervention and/or for any other appropriate purpose.
SOLSS 100 may have a diameter or width 190, which may correspond to the outer diameter of jetter manifold 110. Width 190 may be approximately 30 feet. Jetter pipe 130 and jetter manifold 110 may have a total height of approximately 50 feet, half of which may be buried beneath subsea bottom material after installation, and half of which may extend above the subsea surface. For instance, distance 192 from the bottom of manifold 100 to stabilizing flange 124 may be approximately 24 feet, and distance 194 from the top of stabilizing flange 124 to the top of cap 160 may be approximately 26 feet. Alternative sizes both larger and smaller may be possible for different purposes.
During or after the backfilling of subsea bottom material 230 on the exterior of SOLSS 100, lower interior region 234 of SOLSS 100 may be cleared or maintained clear of subsea bottom material 230 by activation of jets on internally directed surface 114 alone, without activating jets on externally directed surface 112. Jets of jetter manifold 110 may be independently controlled, either individually or in groups arranged by region, size, or any other appropriate criteria. Control of activation of jets of jetter manifold 110 may be via a control link that passes via an umbilical within control cable 224, which may also control other electrical functions, including power for pumps 120. Activation of jets on internally directed surface 114 may fluidize any subsea bottom material 230 in lower interior region 234, which may be educted or evacuated via an evacuation hose connected to a port on jetter pipe 130. Alternatively, fluidized concrete line 200 including connection point 202 may be additionally used to evacuate or educt subsea bottom material from the interior of jetter pipe 130. Fluidized concrete line 200 including connection point 202 may extend above subsea bottom surface 210 due to the buoyancy of connection point 202. Interior 134 of jetter pipe 130 may be filled only or primarily with seawater following the backfilling operation described above.
During an initial deployment of SOLSS 500 on a leaking lateral pipe 510 that includes riser pipe 102, which may be vertical initially or fabricated to be vertical, cut-out 520 may be aligned with lateral pipe 510 on subsea surface 210. Jetting water via jetter manifold 110 may remove subsea surface 210 lowering SOLSS 500 into subsea surface 210. Simultaneously, lateral pipe 510 may move relatively to SOLSS 500 up cut-out 520 until cut-out top 525 is reached. Subsequently, backfilling operations and evacuating the interior of jetter pipe 130 may be performed in the same manner as previously described. Likewise, fluidized concrete may be injected into the interior of jetter pipe 130 to form a bottom seal of jetter pipe 130, and should be injected to a fill point above cut-out top 525, and perhaps well above that point. Additionally or alternatively, cut-out 520 may be provided with a manual closure system enabling cut-out 520 below the position of lateral pipe 510 in a final position to be closed. Closure of cut-out 520 after a jetting operation of SOLSS 500 may be accomplished by motors, springs, latches, either remotely or by using an ROV assist, or by any other appropriate method. Subsequent to the injecting of fluidized concrete into the interior of jetter pipe 130 to a point above cut-out top 525 and curing of the fluidized concrete, operations to complete closure of the jetter pipe 130 using a valve and/or cap may be performed in the same manner as discussed above in regard to SOLSS 100.
A more detailed explanation of exemplary method 600 follows. Depending on water depth and potential bottom conditions, the leak site must be accurately located, marked and engaged by whatever positioning and navigational devices are available. Positioning accuracy should be within ±6 inches or less (if possible). Knowledge of bottom topography and soil conditions and exact riser pipe specifications, condition and orientation would be helpful to assure proper locating, landing, intervention and an overall successful operation.
After proper location and position of the target have been determined, a jetter pipe (outfitted with large motorized gate valve and high volume water pumps) may be deployed concentrically with the severed oil riser pipe directly over the leak site. Positioning and location technology in combination with each ROV may be useful to increase overall reliability of the operation. At this point, the large motorized gate valve is full open allowing oil flow to continue unrestricted vertically upward into the sea. Note also that the fluidized concrete and suction lines can also be deployed with the jetter pipe, or alternatively may be subsequently, remotely connected on the ocean floor using ROV assist.
After accurate deployment of the jetter pipe has been established, high volume water pumps are turned on and commence water jetting and sinkage of the jetter pipe into the seabed until full depth (substantially 24 feet in some exemplary embodiments) has been achieved. During the jetting operation (depending on sea conditions), some tension may need to be held on the lift line to control and maintain vertical attitude of the jetter pipe with respect to the seabed, and to maintain position with respect to the oil riser pipe. ROV support may be required during water jetting. Tensioning may also act to maintain and control sinkage rate into the bottom to prevent overturning of the jetter pipe and inadvertent damage to the oil riser pipe. If embedment is inadequate, the addition of stabilization weights early in the jetting process, prior to complete embedment, may enhance sinkage.
After water-jetting has been completed and proper attitude and positioning of the jetter pipe with regard to the oil riser pipe have been established, the fluidized soil is allowed to settle, backfill and seal against the anchoring flange (connected to the jetter manifold). The settled soil, in combination with the anchoring flange, acts as a strong seabed anchor to resist pullout of the jetter pipe against the force created by the oil-flow pressure after the motorized gate valve has been closed. Approximately 24 hours of settling time may be required for the fluidized soil to backfill. This process can be enhanced by applying the jetter capabilities of an ROV to ensure that all or most of the excavated soil is completely backfilled. The backfilling may extend all the way up to the stabilizing flange. In the event that the jetting operation is unable to embed the jetter pipe to the proper depth, mounding of backfill material around the jetter pipe up to or close to the stabilizing flange at a point above the subsea surface may provide sufficient anchoring of the jetter pipe.
After adequate settling has been established (which may be by observing an increase in lift-line tension against jetter pipe), deployment of “donut-shaped” stabilization weights directly over the jetter pipe may be commenced. Cutouts in the stabilization weights may be aligned with exterior mounted equipment (fetter pumps and gate valve motors and hardware) to avoid the potential for damage to these elements. ROVs may assist in verifying and assisting in this alignment.
It may also be advisable to suction, evacuate or educt fluidized soil trapped inside the jetter pipe to prepare the jetter pipe for the introduction of fluidized concrete.
After the jetter pipe has been stabilized and secured with ample downward weight to resist expected forces caused by oil-flow pressure, fluidized concrete may be introduced from a host vessel at the water surface. Fluidized concrete may be introduced into the cavity around oil riser pipe up to just below the top of its severed orifice to seal and prevent the lower portion of the jetter pipe. In this manner, the jetter pipe may be sealed against oil backflow and seepage, particularly through unconsolidated soils at the bottom of the jetter pipe. At this point, the motorized gate valve remains open to prevent any oil-flow effect on the proper setting of the fluidized concrete. Some tension on the lift line may be maintained and the vertical attitude of jetter pipe may be monitored.
The concrete medium created by the fluidized concrete may seal the SOLSS from oil flow back pressure that could eventually cause oil to leak out around the jetter manifold through coarse, non-cohesive soils after capping off and shutting down the jetter pipe later in the process.
After the concrete seal application has been verified, the motorized gate valve may be closed down, at which point flow from oil riser pipe into the ocean stops. After inspection and testing to verify that oil flow has been terminated, a final pipe cap may be deployed and installed over the jetter pipe, perhaps using ROV assist for the final remotely operated connection. After testing and inspection, the motorized gate valve can be reopened if desired. The final pipe cap may be outfitted with special ports to accommodate re-entry for future access to the oil source, if desired. The final “leave behind” height of the SOLSS structure may be less than 30 feet high and, at its largest point, about 30 feet in diameter.
A weight estimate for each component using a nominal two-inch thick steel for the pipe and flanges are as follows (
The downward, normal force caused by the weight of the system may, in combination with the anchoring effect of the backfilled soil loaded against the anchoring flange, provide a stable bottom platform. The final system requirements and the appropriate element sizes and weights required to safely overcome the expected forces generated by the oil flow pressure may differ than those described above, which are merely exemplary and not limiting. It is anticipated however, that a completed SOLSS could be the basis for start-up of a new oil producing platform or simply sealed off with a possibility for future access.
It may be desirable that the faulted oil riser pipe have a vertical orientation with respect to the bottom. However, a fault in a lateral pipeline can be addressed with the same SOLSS configuration by introducing an access slot, also referred to herein as a cut-out, on one side of the system that is large enough to accommodate the lateral pipe (see
The SOLSS is modular and may enable a second larger SOLSS to be subsequently deployed and erected around and over an initially deployed SOLSS. This feature may enable a different or updated device to be used for a new ocean surface oil rig. This reuse feature can be both cost effective and act to reduce overall environmental impact.
The SOLSS may be employed for a new offshore well, in combination with the drilling operation, to provide at the onset a stable access riser with all the necessary shutoff valves and safety features required to terminate oil flow immediately. This would mean that oil flow may be terminated almost immediately, at the main source, with a drastically reduced effect on the environment. The SOLSS, or elements thereof, may also be incorporated into a blowout preventer, and/or a blowout preventer may be incorporated into the SOLSS. Additionally, the SOLSS may be used in conjunction with other wellhead systems.
Finally, while the SOLSS may be both stable and permanent with a huge resistance to pullout, if removal of this structure is required for some reason, the outside portion of the jetter manifold, for example jets 116 arranged on externally directed surface 112 could be activated to fluidize the soil immediately around the system to assist in its disassembly and recovery.
While only a limited number of preferred embodiments of the present invention have been disclosed for purposes of illustration, it is obvious that many modifications and variations could be made thereto. It is intended to cover all of those modifications and variations which fall within the scope of the present invention, as defined by the following claims.
This application claims the benefit of U.S. Provisional Application No. 61/396,937 filed Jun. 4, 2010, which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61396937 | Jun 2010 | US |
