HYDROGEN CAVERN PAD GAS MANAGEMENT
A method of pad gas management in an underground storage volume including storing a first compressible fluid, determining a transient minimum operating pressure (P trans ), measuring the pressure (P act ), removing at least a portion of the first compressible fluid, concurrently, introducing an incompressible fluid, thereby producing a transient pressure condition controlled by the flow rate of the incompressible fluid, such that P trans <P act . The method may also include a length of casing, permanently cemented into the surrounding rock formations, with a final cemented casing shoe defining the practical endpoint at an approximate depth (D casing ), determining a transient pressure gradient (G trans ) for the underground storage volume, wherein P trans <D casing ×G trans . The maximum removal of the first compressible fluid is controlled such that P min <P act , and wherein the transient pressure condition has a duration (D) of less than 7 days, more preferably less than 5 days.
1 . A method of pad gas management in an underground storage volume, comprising:
storing a first compressible fluid in an underground storage volume,
determining a transient minimum operating pressure (P trans ) for said underground storage volume,
measuring the pressure (P act ), of said underground storage volume,
removing at least a portion of said first compressible fluid from said underground storage volume,
concurrently, introducing an incompressible fluid into said underground storage volume, thereby producing a transient pressure condition,
wherein the transient pressure condition is controlled by the flow rate of said incompressible fluid, such that P trans <P act .
2 . The method of claim 1 , wherein said underground storage volume is an underground salt cavern.
3 . The method of claim 1 , wherein said first compressible fluid is selected from the group consisting of nitrogen, air, carbon dioxide, hydrogen, helium, and argon.
4 . The method of claim 3 , wherein said first compressible fluid is hydrogen.
5 . The method of claim 1 , wherein said incompressible fluid is selected from the group consisting of brine, water, or water slurry.
6 . The method of claim 1 , further comprising;
a length of casing, permanently cemented into the surrounding rock formations, with a final cemented casing shoe defining the practical endpoint at an approximate depth (D casing ),
determining a transient pressure gradient (G trans ) for said underground storage volume,
wherein P trans <D casing ×G trans .
7 . The method of claim 6 , wherein 0.2 psi/ft of depth<G trans <0.3 psi/ft of depth.
8 . The method of claim 7 , wherein 0.25 psi/ft of depth<G min .
9 . The method of claim 1 , wherein said incompressible fluid does not exceed a predetermined maximum flow rate (F max ).
10 . The method of claim 9 , wherein F max is 20 feet per second.
11 . A method of pad gas management in an underground storage volume, comprising:
storing a first compressible fluid in an underground storage volume,
determining a transient minimum operating pressure (P trans ) for said underground storage volume,
measuring the pressure (P act ), of said underground storage volume,
removing at least a portion of said first compressible fluid from said underground storage volume,
wherein the maximum removal of said first compressible fluid is controlled such that P min <P act , and
wherein said transient pressure condition has a duration (D) of less than a predetermined period of time.
12 . The method of claim 11 , wherein said underground storage volume is an underground salt cavern.
13 . The method of claim 11 , wherein said first compressible fluid is selected from the group consisting of nitrogen, air, carbon dioxide, hydrogen, helium, and argon.
14 . The method of claim 13 , wherein said first compressible fluid is hydrogen.
15 . The method of claim 11 , further comprising;
a length of casing, permanently cemented into the surrounding rock formations, with a final cemented casing shoe defining the practical endpoint at an approximate depth (D casing ),
determining a transient pressure gradient (G trans ) for said underground storage volume,
wherein P trans <D casing ×G trans .
16 . The method of claim 15 , wherein 0.2 psi/ft of depth<G trans <0.3 psi/ft of depth.
17 . The method of claim 16 , wherein 0.25 psi/ft of depth<G min .
18 . The method of claim 11 , wherein D is less than 7 days.
19 . The method of claim 18 , wherein D is less than 5 days.