This disclosure relates to methods and systems for injecting and/or sequestering carbon-containing materials in underground wells, and, in some examples, for using the carbon-containing materials for enhanced oil recovery and well abandonment. An example method includes: obtaining a mixture including biochar particles and a liquid; and providing the mixture for injection into an underground well.

A water storage and management system takes water from a water source, such as captured run-off, and through a piping system, directs a flow of the water into an aquifer for storage and future utilization. Using moisture detectors, the system ascertains the water content of different layers or zones of the aquifer and reports this information to a digital processor. The digital processor may utilize this information to issue instructions to one or more control valves to direct the flow of the water into portions of the aquifer which have additional storage capacity. The digital processor may also instruct a submersible pump to withdraw from the aquifer as desired.

A geological storage system of carbon dioxide according to an exemplary embodiment of the present invention includes: an injection pipe that extends to a carbon storage reservoir that includes a plurality of rock grains and brine, from the ground surface, and supplies an injection material that includes carbon dioxide (CO.sub.2) to the carbon storage reservoir; a plurality of pores that are disposed between the plurality of rock grains; and a storage structure that is connected with a part of the plurality of pores and where the carbon dioxide reaches through the plurality of pores and then stored.

A novel system for operating a hydrogen storage cavern is provided. Particularly, the system involves storing high purity hydrogen into a salt cavern without seepage or leakage of the stored hydrogen through the salt cavern walls, by confining the high purity hydrogen gas within the storage cavern under certain pressure conditions.

This disclosure relates to methods and systems for injecting and/or sequestering carbon-containing materials in underground wells, and, in some examples, for using the carbon-containing materials for enhanced oil recovery and well abandonment. An example method includes: obtaining a mixture including biochar particles and a liquid; and providing the mixture for injection into an underground well.

A process for treating waste from a pithead power plant and sequestrating carbon dioxide discharged therefrom is provided. A mixed material of solid waste from the power plant, cement and a mixing liquid is filled into a depleted coal mine and compacted. A hydrating liquid is then injected into the filler after compaction to cause hydration. After that, carbon dioxide discharged from the power plant is injected to mineralize the carbon dioxide, thereby achieving carbon dioxide sequestration and reinforcement of the depleted coal mine. The invention utilizes abundant basic oxides present in the solid waste, and the fact that calcium hydroxide and tobermorite present in the hydrated cement chemically react with the injected carbon dioxide to produce stable carbonates in solid, and thus simultaneously achieves carbon dioxide sequestration, treatment of solid waste, and reinforcement of a depleted coal mine.

A method of storing hydrogen (H.sub.2) gas in a subsurface formation having an injection well, a production well and a heat well. The method includes injecting a H.sub.2-containing fluid stream into the subsurface formation via the injection well to form a storage composition containing a gas-phase mixture, a liquid-phase mixture and a solid matrix; and heating the subsurface formation containing the storage composition via the heat well thereby achieving a storage condition and maintaining the storage condition. The gas-phase mixture includes 10 to 90% of H.sub.2, 5 to 80% of methane (CH.sub.4), 1 to 10% of carbon dioxide (CO.sub.2), and 1 to 10% of nitrogen (N.sub.2). Each % is based on a total volume of the gas-phase mixture. The liquid-phase mixture includes a water-soluble mineral; and the solid matrix includes clay, shale, slate, and minerals.

The disclosure belongs to the field of underground energy storage, and particularly provides a large-deformation underground energy storage device, including a body. The body includes a rubber sealing layer, a negative Poisson's ratio material layer, a large deformation concrete layer and rock layers sequentially nested from inside to outside; an internal storage space is formed in the rubber sealing layer, the negative Poisson's ratio material layer includes a plurality of negative Poisson's ratio material elements connected in sequence, and the large deformation concrete layer is cast from deformable concrete.

An opencast coal mine underground water reservoir comprising an impermeable layer and, provided below the impermeable layer, a water storage space and a purification layer. The water storage space comprises a first water storage space and a second water storage space. The purification layer comprises a first purification layer and a second purification layer. The first purification layer is provided horizontally in the water storage space and divides the water storage space into the first water storage space and the second water storage space. The first water storage space is provided below the impermeable layer and between same and the first purification layer. The second water storage space is provided below the first water storage space and the bottom of the second water storage space is provided at the bottom of the opencast coal mine underground water reservoir. The second purification layer is provided vertically within the second water storage space. The present invention, by constructing the opencast coal mine underground water reservoir, prevents wastage of water resource produced during a coal mining process, and by providing the purification layer in the opencast coal mining underground water reservoir, implements repeated purification of water, prevents environmental pollution, and implements a water conservation mining policy during the coal mining process.

A cavern pressure control method includes storing compressible and possibly incompressible fluids in an underground storage volume, removing a portion or introducing additional incompressible fluid into the underground storage volume, possibly removing a portion or introducing additional compressible fluid into the underground storage volume, thereby producing a net pressure increase rate (P.sub.inc) within the underground storage volume, wherein P.sub.inc is maintained at less than a predetermined maximum increase value (PI.sub.max).