Fluid storage and production

A flow control assembly including a subassembly including an annular safety valve, a shroud, a bushing connecting the shroud to the subassembly at one of two opposing ends of the shroud, and another bushing connecting the shroud to the subassembly at the other of the two opposing ends of the shroud. The method for operating a hydrogen storage and production system including pumping hydrogen into the salt cavern for storage through a borehole and producing hydrogen from the salt cavern through the same borehole.

BACKGROUND

Salt caverns, whether naturally occurring or man made are suitable structures for storage of fluids temporarily or permanently. Commonly salt caverns are filled with brine and hence require displacement of the brine in order to use them for fluid storage. Operation that use salt caverns use two separate boreholes into the formation in order to control fluid movement and debrining operations. While this is technically feasible, it lacks efficiency. Therefore, the art would well receive alternative operations that improve efficiency.

SUMMARY

An embodiment of a flow control assembly including a subassembly including an annular safety valve, a shroud, a bushing connecting the shroud to the subassembly at one of two opposing ends of the shroud, and another bushing connecting the shroud to the subassembly at the other of the two opposing ends of the shroud.

An embodiment of a method for operating a hydrogen storage and production system including pumping hydrogen into the salt cavern for storage through a borehole and producing hydrogen from the salt cavern through the same borehole.

DETAILED DESCRIPTION

Referring toFIG.1, a flow control assembly10is illustrated. The assembly10includes a tubing subassembly12and a shroud14that is disposed about the tubing subassembly12by multiconnection crossovers16at uphole (16a) and downhole (16b) ends of the assembly10, optionally including control line passthroughs. The crossovers attach a single tubular to multiple nested tubulars as illustrated and are sometime referred to as canfield bushings. One or more control line feedthroughs are contemplated with two illustrated in the uphole bushing16a. One of the control lines20feeds a ported safety valve nipple22such as one commercially available from Baker Hughes by product number H82750. It will be appreciated that the nipple22allows hydraulic fluid pressure from line20to reach an insert safety valve on a debrining string to be discussed hereunder. The shroud14is fluid tight with the subassembly12such that an annular fluid space24is created between the subassembly12, the shroud14and the bushings16. This annular space24is accessible by fluid from radially inwardly of the subassembly12through a perforated spacer tube26, through which fluid may relatively freely flow between an ID (Inside dimension)28of subassembly12and the annular space24. The space24is further accessible through an annular safety valve30, which may in some embodiments be or be similar to Baker Hughes product number H73496. Valve30is controlled via control line32. When the valve30is open, fluid may flow through space24and when valve30is closed, the space24is dead headed, thereby preventing fluid flow therethrough. Were the ID28occluded in a region between the tube26and the valve30, flow past the subassembly12would occur only if valve30were open and would be controllable by the valve30. In embodiments, the valve30is an annular safety valve as noted above and is a failsafe configuration. Alternate valves could be used such as packers with separate control lines for setting and unsetting, for example. The assembly10may be employed in any situation where its attributes are needed.

In one situation, the assembly10is employed with a debrining string40, illustrated inFIG.2. When properly nested together the assembly10and debrining string40are referred to herein as a debrining and fluid storage system50. The string40includes an insert safety valve42, such as product number H82708 commercially available from Baker Hughes. Valve42permits or prevents flow through an ID44of the debrining string40. String40also includes seals46aand46bthat straddle the valve42and are receivable in a sealing manner in seal bores in or adjacent nipple22. The bracket48in drawingFIG.2provides for an understanding of the relative positioning when the debrining string40is disposed in the assembly10to create the debrining and fluid storage system50.

Referring toFIGS.1and2simultaneously, the intent is for the reader to understand that debrining string40is to be disposed within subassembly12and at the position indicated by the bracket48. In this position, there are flow capable structures comprising 1) the ID44of the debrining string40,2) a concentric annulus52formed between the string40and the subassembly12, and3) the annular space24in the assembly10(which space becomes part of a flow path including that space and the concentric annulus52. During operation the flow of various fluids is important and is shown via arrows. Arrows54aillustrate flow of fluid uphole and downhole of the seals46aandb, within the concentric annulus52uphole of seal46a. Arrows54billustrated the flow pathway from the concentric annulus52through the ported spacer tube26, through space24and through annular valve30back to concentric annulus52downhole of seal46b. The pathway represented by arrows54ballows for controllability of the concentric annulus flow by interposition of valve30. Arrows56illustrated a pathway flowing within the ID44of string40. It should be noted that neither of these paths expose a cemented casing (not shown) that is radially outwardly disposed of the system50to any of the fluids being pumped through the assembly10in either direction.

In one use of the debrining and fluid storage system50, the arrows54represent a displacing fluid such as CO2 or Hydrogen that is pumped into a salt cavern formation66(seeFIG.3). Upon pumping the fluid into the salt cavern66, brine within the salt cavern is displaced and flowed along the path of arrows56to a remote location such as the surface62. Because the flow along54and the flow along56both include valves, which may be fail safe valves as noted above, the fluid flow in both directions is controlled. This is a requirement for hydrogen operations in some countries. Further, in the case of a hydrogen storage and production system, the hydrogen fluid is segregated from any casing of the wellbore since it is maintained within the concentric annulus52both during debrining of the salt cavern and when later using the formation for storage and production of hydrogen, for example.

A significant benefit of the construction of system50is the removability of string40from subassembly12while under pressure. It will be appreciated that there are no control lines indicated inFIG.2. There is a safety valve42that requires actuation but no line running thereto. This is because the nipple22provides the hydraulic pressure from line20to the valve42when the string40is installed in the subassembly12. This facilitates removal of string40while under pressure through a snubbing unit. In a hydrogen storage and production situation, for example, the ability to remove the debrining string40while under pressure enables the operation of a single borehole configuration for the hydrogen storage and production facility.

Referring toFIG.3, a wellbore system58is schematically illustrated. The system58comprises a borehole60extending from surface62into a subsurface formation64leading to a salt cavern66. Within the borehole60is a string68that includes the assembly10and may also include the string40, which created system50. The string68extends to the salt cavern66in order to convey fluids to and from the salt cavern66. A cement casing70, whether preexisting or newly created is protected from exposure to the fluid being pumped into the salt cavern66, which can be important in the case of Hydrogen.

At surface62is a snubbing unit74to be employed for withdrawing string40from string68while under pressure, which is the case in a Hydrogen storage and production system.

Embodiment 1: A flow control assembly including a subassembly including an annular safety valve, a shroud, a bushing connecting the shroud to the subassembly at one of two opposing ends of the shroud, and another bushing connecting the shroud to the subassembly at the other of the two opposing ends of the shroud.

Embodiment 2: The assembly as in any prior embodiment, further comprising a control line passthrough in one of the bushings.

Embodiment 3: The assembly as in any prior embodiment, wherein the subassembly includes a hydraulic passthrough nipple.

Embodiment 4: The assembly as in any prior embodiment, wherein the nipple includes a seal bore.

Embodiment 5: A debrining and fluid storage system including an assembly as in any prior embodiment, a debrining string having a seal disposed within the assembly.

Embodiment 6: The system as in any prior embodiment wherein the debrining string includes a safety valve.

Embodiment 7: The system as in any prior embodiment wherein the safety valve is actuated by a hydraulic passthrough nipple in the subassembly.

Embodiment 8: The system as in any prior embodiment wherein the debrining string includes two seals straddling the safety valve.

Embodiment 9: A debrining and fluid storage system including a borehole in a formation extending to a salt cavern, a string in the borehole, the string including an assembly as in any prior embodiment.

Embodiment 10: A system as in any prior embodiment further comprising a debrining string disposed within the assembly.

Embodiment 11: A method for debrining a salt cavern including pumping a fluid through an assembly as in any prior embodiment, removing brine from the salt cavern through a debrining string disposed within the assembly.

Embodiment 12: The method as in any prior embodiment, further including removing the debrining string from the assembly while under pressure.

Embodiment 13: The method as in any prior embodiment further comprising operating a snubbing unit to remove the debrining string.

Embodiment 14: The method as in any prior embodiment, further comprising isolating an environment outside of the assembly from Hydrogen.

Embodiment 15: The method for operating a hydrogen storage and production system including pumping hydrogen into the salt cavern for storage through a borehole and producing hydrogen from the salt cavern through the same borehole.

Embodiment 16: The method as in any prior embodiment wherein the pumping is carried out through a flow control assembly having a subassembly including an annular safety valve, a shroud, a bushing connecting the shroud to the subassembly at one of two opposing ends of the shroud, and another bushing connecting the shroud to the subassembly at the other of the two opposing ends of the shroud.