SUBTERRANEAN GAS STORAGE ASSEMBLY
Various embodiments are generally directed to a unit secured in a single subterranean bore. The unit can be configured to store compressed hydrocarbon gas in at least one of a plurality of separate vessels that are respectively attached via at least one retainer. An anchor feature may be employed to center the unit within the single subterranean bore.
- 1. An apparatus comprising a unit secured in a single subterranean bore, the unit comprising a plurality of separate vessels attached via at least one retainer.
- 11. An assembly comprising a unit secured in a single subterranean bore by an anchor feature, the unit comprising a plurality of separate vessels attached via at least one retainer, the anchor feature comprising a self-centering bowspring.
- 19. A system comprising a unit secured in a single subterranean bore, the unit comprising a plurality of separate vessels attached via at least one retainer, an anchor attached to the at least one retainer.
The present application makes a claim of domestic priority to U.S. Provisional Patent Application No. 62/752,041 filed Oct. 29, 2018, the contents of which are hereby incorporated by reference.
Gas may be stored in a subterranean assembly configured, in some embodiments with a unit secured in a single subterranean bore. The unit has a plurality of separate vessels attached via at least one retainer.
In other embodiments, an anchor feature is connected to a unit in a single subterranean bore. The unit consists of a plurality of separate vessels attached via at least one retainer and the anchor feature consists of a self-centering bowspring.
Various embodiments arrange a subterranean gas storage assembly with a unit secured in a single subterranean bore and consisting of a plurality of separate vessels attached via at least one retainer. Each vessel of the plurality of separate vessels is arranged with an inlet check valve and an outlet check valve.
General embodiments of the present disclosure are directed to an assembly for storing compressed gas underground with optimized integration, safety, and reliability.
As the number of machines fueled by gas, such a natural gas and propane, increase, the volume of gas to be delivered grows. The storage of large volumes of compressed, combustible gas above ground can be hazardous, expensive, and cumbersome. That is, above ground storage vessels are required to be constructed of robust materials that are costly, difficult to construct and move, and limiting to the volume of gas that can be stored. As such, there is an industry and consumer interest in storing compressed, combustible gas underground to effectively mitigate the cost and space utilized by above ground gas storage means.
Accordingly, a subterranean gas storage assembly can be utilized with structural and functional embodiments that optimize installation, safety, and operation. For instance, a subterranean gas storage assembly can have a plurality of separate vessels physically connected within a single subterranean bore with a centering feature aligning a longitudinal axis of each vessel with a longitudinal axis of the bore. The centering feature ensures proper vessel placement within the bore during installation and decreases the risk of containment and/or a breach from the bore in the event of a vessel rupture or leak. By positioning multiple vessels in a single bore, as opposed to a single vessel in a bore, a gas volume can be stored in a shallower bore with greater safety and easier installation. The presence of multiple separate vessels additionally provides gas storage options that can be customizable to a diverse variety of environments.
Turning to the drawings,
Although the hydrocarbon storage system 100 can be utilized with the vessel(s) 102 positioned anywhere, some embodiments employ at least one underground vessel 108 positioned wholly, or partially, in a subterranean region 110 defined by being below a ground level 112. As shown, but not required or limiting, the interconnections 106 can be configured to concurrently employ vessels 102/108 positioned above ground 112 and below ground 112. The use of above ground vessels 102 can be efficient to install, but can be plagued by high cost to construct and occupying land that could otherwise be used for other purposes. Also, an above ground vessel 102 can pose a safety hazard due to the risk of unwanted evacuation of hydrocarbons or detonation with malice intent.
Hence, interest has turned towards subterranean vessels 108 storing hydrocarbons to provide reduced safety risk and more efficient use of land.
The utilization of separate vessels 108 allows for different storage configurations, such as different vessel widths 124, different depths 126/128/130 below ground level 112, and different storage pressures. Such different configurations can be controlled by one or more pressure regulating equipment 104 and one or more valves 132 that direct stored hydrocarbons to one or more destinations 134. The ability to customize different vessels 108 in respective bores 122 can efficiently service diverse varieties of hydrocarbon servicing environments, but can pose high installation and service costs compared to above ground storage vessels 102. The use of separated subterranean vessels 108 can also pose safety concerns as moisture 136 accumulates in the bottom of the vessel 108 or an inadvertent leak within a bore 122 causes the vessel 108 to exit the bore 122 like a rocket.
With these issues in mind, embodiments of this disclosure are directed to a subterranean hydrocarbon gas storage within a single underground bore that provides greater safety, reduced installation cost, and lower servicing cost along with customization and above ground land use efficiency.
The respective vessels 142 are packaged collectively into a unit 148 where the longitudinal axis of each vessel 142 is parallel to the longitudinal axis of the bore 144, and the Z axis. Other unit orientations, such as 45 degrees relative to the X axis, are contemplated, but not required. The unit 148 is attached to an anchor feature 150 proximal the bore depth 146. It is contemplated that more than one anchor feature 150 is utilized at different regions of the bore 144, such as proximal the ground level 112. The packaged vessel unit 148 is secured within the bore 144 with cement, or other hardened material, that concurrently contacts the unit 148 and the sidewall of the bore 144. As shown, but not required, a protective collar 152 can partially, or completely, surround a portion of the unit 148 proximal the ground level 112, which protects the interconnections 106 of each vessel 142 to an above ground tap 154.
In a non-limiting embodiment, each unit 148 consists of 7 joints of 13⅜″ P110 casing. Each vessel 142 is designed to have a working pressure of 4500 psi, which corresponds with approximately 75,000 cfg of natural gas storage for the unit 148. The bore 144 may be 48″ or 54″ to provide the efficient packing of 13⅜″ casing, which is the largest size that can routinely handle 4500 psi. The ends of each vessel 142 are sealed with a bottom cap 156 and a top cap 158 positioned on opposite sides. Also, the ends of the vessels 142 are machined in a manner to mate with the respective caps 156/158. The sealing strategy for each vessel 142 consists of a metal-to-metal seat as well as an elastomer seal. Each cap 156/158 may also be threaded onto the casing body 160, which complements the metal-to-metal seat and elastomer seal.
The vertical orientation of the unit 148 means that a large quantity of gas can be stored in a very small footprint, such as 75,000 cfg in a space occupying a 5 ft. in diameter bore 144. The reduced ground level 112 exposure makes the assembly 140 much less vulnerable to external trauma. In fact, the unit 148 is configured to withstand with the total destruction of surface interconnections 106 and distribution systems without releasing stored gas because all safety valves are internal and contained within the respective vessels 142. Further, in the event of a catastrophic release do to vandalism or terrorism, the gas or blast is directed vertically minimizing the impact to surrounding ground level structures.
The assembly 140 may be constructed using a caisson driller to cut a 48″ or 52″ bore 144 is dug to approximately 50 feet below ground level 112. After the dirt is cleared away, a 60″ precast concrete ring can be centered over the bore. The anchor feature 150 self-centers as it is lowered into the bore 144 using a running tool which pushes it to bottom. The anchor feature 150 is then cemented in place leaving a stump sticking up approximately 2′ out of the concrete, proximal the bottom of the bore 144.
The running tool is centered in the bore 144 to ensure the anchor feature 150 is straight and the unit 148 will also be centered. The running tool is left attached during cementing to ensure the latching mechanism is kept clean and free of concrete. The running tool is then unlatched and removed after the cement sets. The anchor feature 150 is held in place by centering bow springs 162. Once the cement has set, an anchoring sub is threaded on to a special cap located on the bottom center of the unit 148.
Next, a circular plate can be positioned over the sub and attached to the star spacer of the unit 148 that attaches the various vessels 142 together, which serves to anchor the assorted vessels 142so they won'"'"'t float while cementing. Finally, an overshot will be attached to the anchor sub, such as with a threaded connection or crossover, it over the stump of the anchor feature 150. The unit 148 can then be raised, oriented, and lowered into the caisson bore 144. The overshot will slide over the stump of the anchor as the unit 148 is lowered to the desired depth 146. Then the overshot will be set to anchor the unit 148 for cementing while leaving enough room below the surface caps 158 so that they may be serviced later, if needed.
It is noted that the unit 148 will float in liquid concrete and the cemented anchor feature 150 ensures the unit 148 stays lowered in the concrete, and centered in the bore 144. Once the cement has set, the individual vessels 142 may be plumbed and interconnections 106 are run through service ports drilled on each side of the precast concrete collar 152. The dirt from the bore 144 can be piled up around the collar 152 to provide an additional blast barrier or barrier to flying debris, such as in a tornado or hurricane.
It is noted that seven vessels 142 are arranged into the unit 148 in
As shown in
The optimized sealing of a vessel 142 with a top cap 158 is complemented by an anchor feature 150 that secures the vessel 142 at a predetermined depth and orientation within a subterranean bore.
In the non-limiting configuration of
The combination of the freely moving plates 216, attached plate 214, and bows 206 ensure the pole 208 is centered within the bore 144 during installation so that the pole 208 contacts the floor 212 in substantially the middle of the bore 144. Each plate 214/216 can be constructed with a width in the X-Y plane that is less than 48″, which allows the anchor feature 200 to efficiently travel into the bore 144 without excessive drag. The triangular shape of the plates 214/216 and the connected bows 206 allow the anchor feature 200 to accurately center the pole 208 within the bore 144 by having three points of contact with the sidewall of the bore 144. For instance, the plates 214/216, bows 206, and/or hinges 210 can physically contact the sidewalls of the bore 144 during installation and after the pole 208 is secured to the bore floor 212 to ensure the pole'"'"'s 208 centralized orientation relative to the bore 144.
The pole 208 can be constructed with one or more installation protrusions 218 that physically attach to an installation tool 220 that lowers the anchor feature 200 into the bore 144.
A retainer plate 240 is positioned about the pipe 236 and nipple 238 with fasteners 242 that connect to a retainer 172. The securing of the retainer 172 to the plate 240 that is disposed between the pipe 236 and vessel bottom cap 156 ensures a solitary unit 148 with vessels locked in place by the retainer 172. Such unitary construction of the assorted vessels corresponds with reliable installation of the foot 232 to the anchor feature so that the unit 148 is centered within the bore at a predetermined depth. In some embodiments, the overshot 234 is configured with articulating jaws that engage the anchor feature in response to the unit 148 being pulled upward, vertically once the unit 148 is at a desired depth.
With the foot 232 securing the unit 148 in place, the bore is filled with cement, or other filling material, to integrate the unit 148 with the bore. The top of the cement may be arranged to be approximately 12″ above ground level in a mound in order to shed water away from the bore. The cement of the bore can be arranged to be below the top caps of the respective vessels of the unit, as shown in
The installation of a gas storage assembly into a bore allows the respective unit vessels to be filled and pressurized with gas hydrocarbons.
An inlet check valve 252 is positioned within the inlet hole 174 while an outlet check valve 254 is positioned within the outlet hole 176 and a plug 256 is positioned within the offset center hole 178. It is noted that each valve 252/254 and plug 256 is integrated into the vessel 142 with a sealing fitting 258 that can comprise any number of metal-to-metal contact surfaces and/or seals. In the non-limiting embodiment of
It is contemplated that the plug 256 is replaced with a valve, meter, or window that contributes to the efficiency and/or safety of the vessel 142. The plug 256 may be replaced with an auxiliary inlet valve 252 or outlet valve 254 to facilitate additional fill, or release, rate. The use of the fitting 258 allows for the configuration of the top cap 158, at will. The outlet valve 254 is configured with an excess flow body 262 that has an extending length, along the Z-axis, and variable internal diameter to mitigate output gas flow from spiking or lacking consistency over time. The flow body 260 is contemplated as a modular component that can be changed by a user depending on the intended use, and safety checks, of the vessel 142.
The construction of the check valve 270 allows for service to be performed in the field without being removed from the vessel 142. That is, the top spring and spool can be removed to reconfigure the check valve 270 as an inlet valve, outlet valve, or pressure relief valve. Manual release of pressure from the vessel 142 can also be facilitated by the check valve 270 by installing a manual release valve body. It is noted that the valve seat can be removed with a special tool. In some embodiments, a 1″ pipe extends from the check valve 270 to within an inch of the bottom of the vessel 142, which allows condensed fluids to efficiently be removed.
With the anchor feature secured downhole, a plurality of vessels packaged together into a unit is lowered and attached to the anchor feature in step 306. Such attachment may be via articulating jaws, threads, and/or keyed connections. The unit, and the respective vessels, is then assembled, oriented, and installed in the bore so that an attachment of the unit and anchor feature can be made. As a result, the unit is centered in the bore due to the anchor feature and ready to receive cement in step 308. It is noted that the unit can have multiple retainers physically contacting the respective unit vessels, which aids in overcoming the buoyancy of the unit and retaining the unit in the bore during step 310. The use of one or more retainers additionally provides resistance to any upward force on the unit over time.
In response to the unit being covered with cement and the bore being substantially filled in step 310, step 312 connects at least one vessel of the unit, or each vessel of the unit, to an above ground tap with interconnection(s), which allow gas to flow to, and from, the respective vessels of the unit. It is contemplated that step 312 involves configuring valves, meters, and/or filters that provide control of vessel inlet and outlet ports.
Next, step 314 fills and pressurizes at least one vessel from an above ground source. The pressurization may be maintained, such as at 4500 psi or more, for any amount of time before decision 316 evaluates if one or more vessels is to be altered. If so, step 318 modifies at least one valve while the valve body remains in the vessel. Such modification of step 318 may change the internal pressure of a vessel, alter inlet rate, alter outlet rate, or add additional gas control equipment to a spare port. At the conclusion of step 318, or if no vessel alteration was called for in decision 316, step 320 maintains a predetermined volume of gas in the vessel(s) of the unit at a predetermined pressure range over time. As such, the compressed gas can be selectively utilized and subsequently replenished to allow efficient distribution and dispensing.
Through the various embodiments of the present disclosure, hydrocarbons, and specifically hydrocarbon gases like natural gas and propane, can be safely stored in large volumes underground. By storing gas in a subterranean bore, an above ground footprint is minimalized and allows gas to be stored at increased pressures more safely than in above ground tanks. The configuration of multiple separate vessels in a single subterranean bore increases safety and allows customized gas storage parameters with reduced installation costs compared to positioning individual vessels in separate underground bores. As a result, gas storage is optimized with the various embodiments of a subterranean gas storage assembly.