Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
  • B65G—TRANSPORT OR STORAGE DEVICES, e.g. CONVEYORS FOR LOADING OR TIPPING, SHOP CONVEYOR SYSTEMS OR PNEUMATIC TUBE CONVEYORS
  • B65G5/00—Storing fluids in natural or artificial cavities or chambers in the earth
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21F—SAFETY DEVICES, TRANSPORT, FILLING-UP, RESCUE, VENTILATION, OR DRAINING IN OR OF MINES OR TUNNELS
  • E21F17/00—Methods or devices for use in mines or tunnels, not covered elsewhere
  • E21F17/16—Modification of mine passages or chambers for storage purposes, especially for liquids or gases
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
  • F17C3/00—Vessels not under pressure
  • F17C3/005—Underground or underwater containers or vessels

Definitions

• the latter is injected into a spent petroleum or natural gas bed or stratum.
• the storage capacity of the under ground reservoir formed by this bed is, among other factors, a function of the free space remaining in the said bed due to its previous working.
• the latter is injected into a previously worked, abandoned coal mine filled with ground water.
• a mine forms a great U-shaped underground reservoir with at least two shafts which serve respectively to convey water and gas.
• gas is above the adjustable level of water, under a pressure corresponding to the height difference between said level and the surface of the ground.
• the storage capacity of said reservoir is proportional to said pressure and depends on the gas volume increasing when exhausting water from the mine.
• the presence of water reduces the possibility of diffusion, fixation, absorption and adsorption of the gas in the rock of the mine, namely through decreasing of the rock permeability.
• the storage capacity of said reservoir is thus practically limited to the geometrical volume of the mine cavities above the water level in said mine.
• the gas is introduced into natural or artificial underground reservoirs found in suitable impervious geological structures such as salt formations, non-fractured coherent rocks (argillaceous limestones, schists, crystalline rocks, quartzites, limestones) or plastic rocks (clays).
• suitable impervious geological structures such as salt formations, non-fractured coherent rocks (argillaceous limestones, schists, crystalline rocks, quartzites, limestones) or plastic rocks (clays).
• salt formations such as salt formations, non-fractured coherent rocks (argillaceous limestones, schists, crystalline rocks, quartzites, limestones) or plastic rocks (clays).
• non-fractured coherent rocks argillaceous limestones, schists, crystalline rocks, quartzites, limestones
• plastic rocks clays
• the object of the present invention is a new process for storing gas, especially combustible gas, in which the true storage capacity of the underground reservoir is greater than its own inherent volume.
• the gas to be stored is introduced into the gassy coal deposit previously partially worked, degassed and unsaturated with water, at a relatively high pressure so as to increase the absorption of said gas in the rocks of the coal deposit and, in particular, the adsorption of said gas by said rocks.
• the introduction of the gas into the underground reservoir may be made in an unworked coal deposit.
• a coal mine which has previously been partially worked, degassed and unsaturated with water may preferably be used to store this gas.
• Such a mine has in fact the advantage of having an inherent volume which is larger than that of the not yet worked deposit and which is due especially to the residual volume of the cavities excavited during he mining operations.
• such a mine has also an enormous gas-rock contact surface represented by the surface of all these excavated cavities as well as by the multitude of cracks and fissures caused by the movements of the rocks due to these mining operations.
• the partial removal of gas or the desorption of thecoal deposit surrounding the part of the inherent volume formed by the mining operations facilitates the absorption of the gas injected into the mine and in particular, the adsorption of this gas by the rocks of the said deposit.
• the gas is introduced into the coal deposit which is previously and partially worked and degassed, also unsaturated with water.
• the diffusion and absorption of gas in the rocks of a coal deposit result in phenomena which depend on the internal structure characteristic of some rocks of the coal deposit (coals and coal-bearing schists).
• the specific internal surface of some coals may attain, for example, mP/gram.
• the gaseous exchanges between the gas outside the rock and that absorbed by the internal structure of the rock depend especially on the nature and the pressure of the external gas in contact with the rock, the magnitude of the contact surface between the external gas and the rock, the nature, internal structure, permeability, magnitude of the internal surface, temperature, moisture and adsorbent power of the rock.
• the external gaseous phase means the gas found in the part of the inherent volume of the measure which is exterior to the rock and which is formed by the residual volume of all the cavities due, for example, to former mining operations and to the shafts for access to the deposit;
• the internal gaseous phase means the gas found in the part of the inherent volume of the deposit which is inside the rock and filling the free spaces of its internal structure;
• adsorbed phase means the gas found in the internal structure of the rock and covering the internal surface thereof.
• the internal phase and the adsorbed phase of the gas which are adsorbed by the internal structure of the rock are normally in equilibrium with the external gaseous phase, this equilibrium depending among other factors on the pressure of this external gaseous phase.
• the result is that the diffusion of the gas into the rocks of the coal deposit and the absorption of this gas by these rocks are facilitated by an increase of pressure in the external gaseous phase.
• the gas to be stored is introduced at a relatively high pressure in order to facilitate the absorption of this gas in the rocks of the coal deposit.
• the calorific power of the gas of the external phase is gradually increased and it is regulated with relation to that of the gas to be stored in order to make is approximately equal to the latter in thermal power.
• Such an extraction of the external gas from the gassy coal-mine is effected before any injection of gas to be stored into the underground reservoir formed by this mine.
• the preparation of a storage reservoir from a gassy coal mine previously partly worked, degassed and unsaturated with water is thus both simple and particularly economical.
• this residual volume of the underground reservoir formed in this coal mine by the mining operation is about 10,000,- 000 m.
• This volume external of the rock of the underground reservoir is filled with a gas which is denoted by external gas or external gaseous phase.
• this external gas is from the air of the mines having, for example, the following average composition:
• the above-mentioned external volume of the underground reservoir is defined by the rocks of the coal deposit, which include among others coals and schists.
• This absorbed pit gas is composed of an internal gas and an adsorbed gas or, in other words, an internal gaseous phase and an adsorbed phase.
• This absorbed pit gas is at a pressure of about 1 atmosphere in the vicinity of the contact surface between the external gas and the rocks and which increases progressively, for example up to 50 atmospheres, in proportion as it is removed from the degassed and desorbed zone of this contact surface towards the non-desorbed and virgin zone of the coal deposit.
• This pit gas absorbed by the rocks of the coal-measures has approximately the following average composition:
• the underground storage reservoir is prepared from this worked coal mine by a first simple operation consisting in extracting, after sealing the shafts, the gas of the external phase while maintaining it at low pressure with respect to that of the internal and adsorbed phases.
• the external gaseous phase is maintained at a pressure of 1 atmosphere by drawing off while the internal and adsorbed phases of the virgin deposit are at a pressure of about 50 atmospheres.
• the coal mine is degassed and desorbed from its constituent pit gas by the extraction in question, while it is enriched in methane, the said external gaseous phase.
• the calorific power of this external gaseous phase is thus increased and the adjustment of this calorific power can be carried on by the single extraction mentioned above until, for example, the following average composition is attained:
• N equal to that of the calorific power of the gas to be stored.
• the gas to be stored is introduced into the underground reservoir-formed by the said coal mine.
• This introduction of the gas to be stored is made preferably under a relatively high engine pressure but able to be varied, for example, from 1 to 50 atmospheres according to the amount of gas to be stored.
• the external gaseous phase is also found at this variable pressure of 1 to 50 atmospheres and consequently this external gaseous phase which fills the volume external to the rocks of the deposit, partly diffuses into these degassed, desorbed and unsaturated with water rocks Where it is absorbed.
• These quantities of gas absorbed by these rocks increase respectively the internal and adsorbed phases, the internal pressure of which increases as a function of the pressure of the external gaseous phase.
• the storage capacity of the underground reservoir formed by the aforesaid coal mine is by no means limited to that of the inherent volume of the mine and, under a pressure of 10 atmospheres, a storage capacity of, for example, 500,000,000 111. N may be obtained.
• Process for storing hydrocarbonaceous gas comprising withdrawing from a gassy coal mine which has previously been partially worked and which is unsaturated with water, the gas which is external to the rock of the coal deposit of said mine, until the heating value of the gas being withdrawn is at least about equal to that of the gas to be stored, and thereafter introducing said gas to be stored into said coal mine at superatmospheric pressure so as to promote adsorption of said gas to be stored by the partially worked coal formation.

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• Engineering & Computer Science (AREA)
• Mining & Mineral Resources (AREA)
• Life Sciences & Earth Sciences (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Geochemistry & Mineralogy (AREA)
• Environmental & Geological Engineering (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Filling Or Discharging Of Gas Storage Vessels (AREA)

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Cited By (4)

Citations (4)

• 1966
  • 1966-05-27 GB GB23764/66A patent/GB1145913A/en not_active Expired
  • 1966-05-27 NL NL6607457A patent/NL6607457A/xx unknown
  • 1966-05-27 FR FR63263A patent/FR1499998A/fr not_active Expired
  • 1966-05-31 DE DEA52614A patent/DE1253659B/de active Pending
• 1967
  • 1967-05-01 US US634824A patent/US3462957A/en not_active Expired - Lifetime

Patent Citations (4)

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