SIDE ENTRY FLOW SPOOL AND USE THEREOF
The invention provides a side entry flow spool for use in production of oil and gas from a well. The side entry flow spool provides for a shift in the direction of flow of the hydrocarbons, from horizontal to vertical.
This application claims the benefit of U.S. Provisional Application No. 61/719,719, filed Oct. 29, 2012, which is incorporated herein by reference.FIELD OF THE INVENTION
This invention relates to a side entry flow spool and a method of using the side entry flow spool to export hydrocarbons from a horizontal flow line. The side entry flow spool is preferably integrated with a subsea landing string.BACKGROUND
Safety and environmental concerns related to subsea production of oil and gas have heightened greatly, and there is renewed interest in developing systems that can be used to respond to the loss of containment of the oil and gas at a subsea wellhead. The environmental damage that can be caused by loss of containment of oil and gas at a subsea wellhead is enormous and steps are being taken to address both preventing such a loss of containment and regaining control and containment in the event that oil and gas does leak to the environment.
To fulfill the requirement to transport hydrocarbons from a seabed installation to a production/storage/testing facility at the surface it is necessary to develop an enabling interface between the seabed system and the surface system. The requirement for this item is driven by a need to function effectively in all water depths from ultra deep, about 3000 m, to shallow, about 100 m.SUMMARY OF THE INVENTION
The invention provides a side entry flow spool comprising a forging with flanges located at the top and bottom; an inlet located on the side; an outlet located at the top; and an internal cavity that is fluidly connected to the inlet and outlet wherein there is no opening at the bottom.
The side entry flow spool may be integrated with a subsea landing string via a latch to enable contained flow of well fluids from a damaged offshore well to a vertical marine riser connected to a capture vessel located at an offset distance from the incident well.
The invention provides a system for transporting hydrocarbons from a subsea location to the surface of the water. The main feature of the invention is the side entry flow spool and its use in conjunction with standard equipment that is readily available and can be rapidly deployed anywhere in the world. The system may be used to transport leaking hydrocarbons that are captured by any subsea capture apparatus known to one of skill in the art. The system provides for the transport of the hydrocarbons from the leaking well a safe distance away and then to a standard floating vessel that does not require any custom modifications. This allows a leaking well to be contained using industry standard equipment in almost all aspects. The system may also be used to transport produced hydrocarbons from a production well.
The side entry flow spool may be used equally well in deep water or in shallow water, although the other equipment used would be different. For example, in deepwater, the side entry flow spool would be connected through a riser to a floating vessel. In shallow water, the flow spool could be connected to a freestanding production riser that transports the hydrocarbon to a jack-up vessel. Further the need for BOPs and the location of BOPs could be different depending on the water depth.
The side entry flow spool is designed to allow connection between any subsea architecture to any riser system which connects with a surface vessel, mobile oil drilling unit, jack-up, work barge or other system. The side entry flow spool if structurally capable of working in the water depth in the range of from less than 100 m to about 3000 m or deeper.
The side entry flow spool is a bespoke piece of equipment designed to allow the conduit of wellbore fluids to pass from the subsea architecture to a vertical riser located at an offset distance from the well which transports the product to a MODU or well intervention vessel. The side entry flow spool has the ability to marry these systems between the extremes of ultra deepwater with a drillship/BOP and marine riser to shallower scenarios which only require a jack-up and free standing production riser.
The invention will be further described with reference to the illustrative embodiments shown in the drawings. The invention however is not limited to the embodiments depicted in the figures.
The inlet 106 may extend in the horizontal direction for connection with flow lines and/or jumpers carrying hydrocarbons. The inlet may be connected to the flow lines and/or jumpers with any type of connection known to one of skill in the art. The connection may be flanged or otherwise, but it is preferred to use a connection that is easily installed due to the desire to rapidly deploy this system.
The inlet of the side entry flow spool may be flush with the spool or it may comprise a horizontal tubular that is connected to an opening on the side of the spool. Alternatively the horizontally extending tubular may be integral with the body of the side entry flow spool. The inlet may also comprise one or more isolation valves. A double valve arrangement provides industry standard isolation. The inlet is preferably perpendicular to the outlet such that the horizontal flow is converted into vertical flow in the side entry flow spool. Other embodiments may include an angled inlet at an angle other than ninety degrees to the outlet.
The side entry flow spool may comprise one or more additional inlets 107 that can be used for example, for chemical injection and/or flushing of the spool to remove solids that may accumulate at the point where the hydrocarbon changes direction from horizontal to vertical. The inlets may also be used for pressure monitoring or for connecting to another side entry flow spool for daisy-chain production. The inlets may be located on opposite sides of the side entry flow spool or they may be located at other points along the side of the spool.
The side entry flow spool is preferably machined from a single piece of metal. The flow spool must be able to withstand the forces that are exerted on it from within by the passage of the hydrocarbon and externally by the connections to other systems. The side entry flow spool may be coated with a protective coating to prevent corrosion and/or erosion to the internals of the flow spool. The corrosion may be caused by exposure to carbon dioxide, hydrogen sulfide and/or other components of the hydrocarbons passing through the spool. The flow spool is designed to withstand all types of conditions so that it can be used in different applications without modification.
The side entry flow spool preferably has API flanges on the top 114 and on the bottom 112 to provide for connection to other subsea production equipment. The side entry flow spool needs to be anchored to the seafloor and it is typically connected to a riser or BOP to carry the hydrocarbons to the surface of the water.
In one embodiment, a drill string 102 is inserted at least partially below the seafloor 116 so it can be used as an anchor point for the side entry flow spool. The drill string does not provide for the production of hydrocarbons, but is only inserted deep enough to anchor the flow spool.
In another embodiment, the flow spool may be connected to a new or existing well head. Further, in another embodiment where the flow spool is used in shallow water, the side entry flow spool may be anchored by a mud mat.
The side entry flow spool is preferably connected to a standard wellhead connector 110 that is located on the drill string, wellhead or mud mat. The standard wellhead connector has API flanges and is connected to the side entry flow spool using these flanges. Alternatively, the flow spool could have a wellhead connector on the bottom that would connect to the wellhead.
The anchor point provides sufficient force to keep the side entry flow spool anchored in place regardless of the forces exerted on it by the systems connected to the inlet(s) or outlets of the flow spool.
The side entry flow spool does not have an outlet in the direction of the seafloor, so the hydrocarbon is routed in a vertically upwards direction. In one embodiment, the outlet of the side entry flow spool is connected to a blowout preventer 104. In another embodiment, the outlet of the side entry flow spool is connected directly to a riser. The side entry flow spool may be connected to a wellhead connector via the top flanges of the side entry flow spool. The blowout preventer would then be connected to the wellhead connector.
Further, the position of the blowout preventer allows the system to be pressure tested before use to ensure containment of the hydrocarbons. The blowout preventer may be any suitable type of blowout preventer or the system may comprise more than one blowout preventer forming a blowout preventer stack.
The blowout preventer is connected to a riser that extends upward towards the surface of the water. The riser may be a top-tensioned riser. A production or test string may be located inside the riser to allow for the passage of hydrocarbons through the string upwards to the vessel or platform on the surface of the water.
The side entry flow spool may be designed to allow a subsea test tree or oilfield tubular string to be connected to the flow spool, with a pressure seal. This is preferably accomplished by the use of a latch on the bottom of the string that latches into the side entry flow spool. The flow spool can be machined or otherwise designed to allow the latch to securely connect to the side entry flow spool. The latch would be located within the outlet of the side entry flow spool and preferably connected to the internal inner diameter section of the outlet of the flow spool. Crossover connections can interface with this latch by simple compatible thread form.
In one embodiment, the side entry flow spool is used in combination with a subsea apparatus that is used to capture hydrocarbons that are leaking into the water. Flow lines or pipelines may be installed that extend from the source of the leak to the side entry flow spool which may be located a safe distance away from the leak, for example 500 to 2000 meters.
In one embodiment, a drill ship through a drilling riser, drills a short distance into the seabed and inserts one or more pieces of drill string at last partially below the mud line. The drill string acts as an anchor point for the system. A side entry flow spool is connected to the drill string. The side entry flow spool is connected to the flow lines carrying hydrocarbon. The side entry flow spool has one or more inlets on the side and one outlet on the top of the spool. The outlet is connected to the floating vessel on the surface of the water. The connection is preferably via a production string or well test string that is run through the drilling riser. A blowout preventer is preferably located between the side entry flow spool and the drilling riser.
In this embodiment, the drill string, drilling riser, drill ship and blowout preventer are industry standard equipment used to drill subsea oil and gas wells. Suitable drill ships are available throughout the world and this availability provides one of the advantages of this invention. These ships can respond quickly to a leaking wellhead anywhere in the world without requiring the transportation of any large custom equipment. Additional advantages are that the majority of the equipment needed for this operation is known and used for similar purposes in deepwater exploration and production. The use of this equipment does not require additional training and testing before use in this application.
The drill ship may have facilities to separate and treat the oil and gas that is being produced from the leaking well. In the alternative, another floating vessel may be moored near the drill ship and the hydrocarbons passing up through the drilling riser may be exported to this other floating vessel for storage, separation or disposal. For example, the gas being produced from the leaking wellhead may be temporarily flared during the time period required to control the well. The other floating vessel may be a shuttle vessel that stores hydrocarbons and then transports them to a larger facility and then returns to receive additional hydrocarbons.
The drilling riser may be a top tensioned riser. A top-tensioned riser is a completely vertical riser system that extends vertically until just below the floating vessel. The floating vessel will move with the motion of the waves which could result in damage to the riser or subsea blowout preventer and side entry flow spool. A top tensioned riser is a rigid riser that is fixed to the seafloor and tensioned at the top. The top tension can be provided by buoyancy devices that are connected to the top of the riser. The fluid flowing through the riser may pass from the top of the riser through flexible lines to the floating vessel. In this manner the movement of the floating vessel does not directly affect the riser or put stress on the riser.
The system may be used to capture hydrocarbons from a subsea apparatus placed on a leaking wellhead. In another embodiment of the invention, the side entry flow spool may be used to export hydrocarbons from a regular producing well and provide the connection between a horizontal flowline and a vertical riser.
The invention also provides a method of capturing hydrocarbons from the leaking wellhead as further described herein. The method comprises first installing a capping stack on top of a damaged subsea wellhead. Flow lines are installed along the mud line and are connected to the capping stack. These flow lines may be connected to a flow line end termination facility, manifolds or other standard subsea oil and gas production equipment. The oil recovery system comprising the blowout preventer, riser, side entry flow spool and anchor point are installed some distance away from the leaking wellhead. Everything is connected and hydrocarbons can begin flowing to the floating vessel while the well is brought back under control.
1. A side entry flow spool comprising a forging with flanges located at the top and bottom; an inlet located on the side; an outlet located at the top; and an internal cavity that is fluidly connected to the inlet and outlet wherein there is no opening at the bottom.
2. The side entry flow spool of claim 1 further comprising a machined internal profile for connection with a latch mechanism located inside the forging that is suitable for connection with a subsea test tree or oilfield tubular string.
3. The side entry flow spool of claim 1 further comprising one or more additional inlets located on the side of the forging.
4. The side entry flow spool of claim 3 wherein the one or more additional inlets are suitable for one or more of the following: injecting treatment fluids, connecting with another side entry flow spool, monitoring pressure or flushing the system.
5. The side entry flow spool of claim 1 wherein the inlet is a tubular that is integral to the side entry flow spool.
6. The side entry flow spool of claim 1 wherein the flanges are API standard flanges that can be connected with standard oil and gas industry equipment.
7. The side entry flow spool of claim 1 wherein the bottom of the side entry flow spool is suitable for connection to a wellhead connector.
8. The side entry flow spool of claim 1 wherein the top of the side entry flow spool is suitable for connection to a blowout preventer or directly to a production string.
9. The side entry flow spool of claim 1 wherein the top of the side entry flow spool is suitable for connection to a wellhead connector so that other standard oil and gas production equipment can be connected to the wellhead connector on top of the side entry flow spool.