Underwater oil and gas leak containment systems and methods

A system and method are disclosed for containing an underwater gas or oil leak. The system and method may include a vortex device comprising a vortex chamber, a high pressure inlet tangentially engaging the vortex chamber, a low pressure inlet axially engaging the vortex chamber, and a low pressure outlet axially engaging the vortex chamber opposite the low pressure inlet. The vortex device may be positioned underwater proximate an underwater leak. A vortex may be generated within the vortex device. The vortex device may then collect a leak flow issuing from the underwater leak. In certain embodiments, the vortex device may collect the leak flow via the low pressure inlet. In other embodiments, the vortex device may collect the leak from via the high pressure inlet.

BACKGROUND

1. The Field of the Invention

This invention relates to containment systems and, more particularly, to novel systems and methods for containing underwater gas and oil leaks.

2. The Background Art

As evidenced recently in the Gulf of Mexico, it is difficult to contain a gas and oil leak located deep underwater. It is particularly difficult when uncontrolled adiabatic expansion makes the gas very cold. Accordingly, what is needed is a system and method that addresses the unique challenges of containing a gas and oil leak located deep underwater.

BRIEF SUMMARY OF THE INVENTION

In view of the foregoing, in accordance with the invention as embodied and broadly described herein, methods and apparatus are disclosed as including a vortex device comprising a vortex chamber containing a vortex rotating therewithin. A vortex chamber may have a relative high pressure at the perimeter of a vortex contained therewithin and a relative low pressure near the center of the vortex. By having different diameter openings at the center of the vortex chamber, a flow may be induced through the center of the vortex. This flow may enter at a smaller, low pressure, axial inlet and leave via a larger, low pressure, axial outlet due to the pressure gradient within the vortex.

In certain embodiments, to generate a vortex within a vortex chamber, a vortex device may include a high pressure inlet and, optionally, a high pressure outlet. A high pressure inlet may direct a driving fluid tangentially into a vortex chamber to inducing rotation of the fluid therewithin.

In selected embodiments, a vortex device may be configured to execute an axial inlet method to contain an underwater gas and oil leak. This method may use induced flow into the center of the vortex chamber (e.g., via a low pressure inlet). The main objective in this embodiment may be to induce and maintain a flow of mixed diluent and recovered oil and gas out the low pressure axial outlet that does not freeze as it rises within piping to the surface. Accordingly, this method may be the most robust approach for very extreme conditions where there is a lot of cold gas.

In selected alternative embodiments, a vortex device may be configured to execute a tangential inlet method to contain an underwater gas and oil leak. This method may bring the oil and gas, along with any entrained sea water, into the vortex of a vortex chamber through a tangential high pressure inlet. In such a configuration, the flow into the vortex chamber may be caused by either a negative pressure within the vortex chamber or because a sound mechanical connection has been made to existing sea-floor piping that can withstand a positive pressure.

DETAILED DESCRIPTION OF SELECTED EMBODIMENTS

Referring toFIG. 1, certain devices are disclosed in U.S. Pat. Nos. 4,409,746 and 4,449,862, which patents are hereby incorporate by reference. A vortex device10in accordance with the present invention may share certain similarities in structure to those devices, but may be modified or connected or utilized differently to contain an underwater gas and oil leak.

In selected embodiments, a vortex device10in accordance with the present invention may include a vortex chamber12. A vortex chamber12may contain a vortex rotating about an axis of rotation14. A vortex chamber12in accordance with the present invention may have a relative high pressure at the perimeter of a vortex contained therewithin and a relative low pressure near the center of the vortex. By having different diameter openings at the center of the vortex chamber12, a flow may be induced through the center of the vortex (e.g., along the axis of rotation14). This flow may enter at a smaller, low pressure, axial inlet16and leave via a larger, low pressure, axial outlet18due to the pressure gradient within the vortex.

To generate a vortex within a vortex chamber12, a vortex device10may include a high pressure inlet20and, optionally, a high pressure outlet22. A vortex chamber12may have a generally cylindrical shape. A high pressure inlet20may direct a driving fluid tangentially into a vortex chamber12to induce rotation of the fluid therewithin. Should a high pressure outlet22be included, it may also tangentially engage the vortex chamber12and, thereby, remove driving fluid from the vortex chamber12without impeding (and potentially aiding) the induced rotation.

There may be no particular water depth limitation for use of a vortex device10in accordance with the present invention. In general, a vortex device10will work better in deeper water because there are greater differentials in pressure available. The vortex device10and associated piping may be selected to withstand the negative pressure at depth urging collapse thereof.

A system in accordance with the present invention may use a vortex together with a diluent of sufficient volume to prevent freezing of any water entrained in the recovery flow. Any suitable process or processes may be employed at the surface to separate the diluent and recover the oil and gas. In certain embodiments, the most economical diluent may be sea water. However, other fluids may be used as the diluent. For example, in selected embodiments, lighter fluids may be used to facilitate separation of oil and gas within the vortex. Fluids having chemical properties that may further reduce the chances of ice or other solids forming on the walls of the vortex chamber and associated piping may also be used as a diluent.

Referring toFIG. 2, in selected embodiments, a vortex device10may be configured to execute an axial inlet method to contain an underwater gas and oil leak. This method may use induced flow into the center of a vortex chamber12. The main objective in this embodiment may be to induce and maintain a flow of mixed diluent and recovered oil and gas out the low pressure axial outlet18that does not freeze as it rises within piping to the surface. Accordingly, this method may be the most robust approach for very extreme conditions where there is a lot of cold gas.

In selected embodiments, a flow of oil and gas may enter a vortex within a vortex chamber12directly through an axial low pressure inlet16. The inlet16may simply be an opening formed in the wall of the vortex chamber12and lack any piping on which ice may form. In this way, any solid formation would be more likely to be entrained in the flow rather than building up on surfaces.

The fluid entering a vortex chamber12through a high pressure inlet20may come from a surface vessel or platform and be pumped down. The fluid within a high pressure inlet20may be sea water recovered from the flow back to the surface. Alternatively, the fluid may be any other fluid deemed appropriate as a driving fluid. The high pressure outlet22may be optional, depending upon operating conditions and the fluid being used at the high pressure inlet20.

Some method of applying back pressure or regulation may be used at the surface vessel or platform. Additionally, regulation of the axial inlet16and outlet18flows may be implemented using concentrically operating valves on the vortex chamber12. Any control device that can produce a variable diameter orifice may be used for this regulation, including those that use a thick elastomer with a control fluid behind it to reduce the orifice diameter.

A vortex device10in accordance with the present invention may be held in place proximate an underwater leak in any suitable manner. The positioning and orientation of a vortex device10may depend on the embodiment and conditions involved. For example, the positioning and orientation may depend on whether the vortex device10intakes a leak flow (e.g., oil, gas, or some combination thereof) through a low pressure inlet16, a high pressure inlet20, or the like. Suitable mechanisms for positioning or orienting a vortex device10may include inherent weight (e.g., the weight of the device10itself), one or more external anchors, anchor lines (e.g., cables, chains, etc.), substantially rigid or rigid positioning arms or linkages, brackets, conduits conducting a leak flow into an inlet16,20in a vortex device10, or the like, or combinations or sub-combinations thereof.

Referring toFIG. 3, in selected alternative embodiments, a vortex device10may be configured to execute a tangential inlet method to contain an underwater gas and oil leak. This method may bring the oil and gas, along with any entrained sea water, into the vortex of a vortex chamber12through a tangential high pressure inlet20. In such a configuration, the flow into the vortex chamber12may be caused by either a negative pressure within the vortex chamber or because a sound mechanical connection has been made to existing sea-floor piping that can withstand a positive pressure.

In the case of negative pressure within the vortex chamber12, it would be negative because of hydrostatic pressure outside being higher than that inside because of density differences between water, oil, and gas. Conditions may have to be such that any piping forming the tangential inlet20would not freeze up.

Once the flow enters the vortex within the vortex chamber12, the lighter gas may move to the center low pressure region of the vortex, where it may mix with sea water entering the axial inlet16of the vortex injector, and then exit through the axial outlet18and travel to the surface in piping as a mixture of gas, water and possibly oil, and then connect to a surface vessel or platform for containment and processing. Oil, and possibly water, may exit through the tangential high pressure outlet of the vortex chamber and travel in piping to a surface vessel or platform for containment and processing. However, the use of the tangential high pressure outlet22may be optional, depending upon operating conditions.

It may be that if the tangential high pressure outlet22is used, an extension pipe through the core of the vortex chamber12would be desirable to convey sea water preferentially to the axial outlet18. This may support entrainment and warming of the gas flow to prevent freezing by mixing sufficient sea water to warm the gas above a freezing temperature.

Various optional control values24may be included as desired or necessary. For example, control of the gaseous flow out of the axial outlet18to a surface vessel or platform may be desirable. This control may be enforced by surface facilities. Additionally, it may be desirable to regulate flow of sea water into the axial inlet16. This may be accomplished using annular control valves similar to those discussed above with respect to the axial inlet method, and to control the flow from the tangential outlet22to the surface as well.

Referring toFIGS. 1-3, depending upon the head required at the surface, above sea level, it may be necessary to induce flow from the axial outlet18and tangential outlet22(if any). This may be done by adding a compressed gas (e.g., air) such that it enters the outlet flow stream. It could be added just past the pump supplying the driving tangential inlet flow, or to the axial and tangential outlet flows near the vortex chamber12. Flow may be induced this way with a single pipeline from the surface (plus a small air/gas line to get it started) connected only to the axial outlet18. The flows within axial inlet16and the tangential inlet20may enter at the vortex chamber12without a connection to the surface.

In embodiments where the oil and gas are entering the tangential inlet20, a significant differential pressure across the vortex flow to produce adequate mixing may be created by making the axial inlet16quite small, just enough to let in enough water to warm up the mixture and keep it from freezing. In embodiments where the oil and gas are entering at the axial inlet16, the pipe to the surface may be large enough to carry the leak flow plus a lot more, or there may need to be a fairly tight connection between the axis of the vortex chamber12and the leak source such that little water could get in from that direction.