Cavern pressure management

Abstract

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).

Claims

1. A method of pressure management in an underground storage volume, comprising: storing a compressible fluid in an underground storage volume, storing an incompressible fluid in said underground storage volume, and introducing additional compressible fluid into said underground storage volume, thereby producing a net pressure increase rate (P.sub.inc) within said underground storage volume, wherein P.sub.inc is maintained at less than a predetermined maximum increase value (PI.sub.max), wherein PI.sub.max is 100 psi/hr, wherein said compressible fluid is hydrogen.

2. The method of claim 1, wherein said underground storage volume is an underground salt cavern.

3. The method of claim 1, wherein said incompressible fluid is selected from the group consisting of brine, water, or water slurry.

4. The method of claim 1, wherein PI.sub.max is 75 psi/hr.

5. A method of pressure management in an underground storage volume, comprising: storing a compressible fluid in an underground storage volume, storing an incompressible fluid in said underground storage volume, and introducing additional incompressible fluid into said underground storage volume, producing a net pressure increase rate (P.sub.inc) within said underground storage volume, wherein P.sub.inc is maintained at less than a predetermined maximum increase value (PI.sub.max), wherein PI.sub.max is 100 psi/hr, wherein said compressible fluid is hydrogen.

6. A method of pressure management in an underground storage volume, comprising: storing a compressible fluid in an underground storage volume, storing an incompressible fluid in said underground storage volume, and introducing additional compressible fluid into said underground storage volume, and concurrently, removing a portion of said incompressible fluid from said underground storage volume, thereby producing a net pressure increase rate (P.sub.inc) within said underground storage volume, wherein P.sub.inc is maintained at less than a predetermined maximum increase value (PI.sub.max), wherein PI.sub.max is 100 psi/hr, wherein said compressible fluid is hydrogen.

7. A method of pressure management in an underground storage volume, comprising: storing a compressible fluid in an underground storage volume, storing an incompressible fluid in said underground storage volume, and removing a portion of said compressible fluid from said underground storage volume, and concurrently, introducing additional incompressible fluid into said underground storage volume, producing a net pressure increase rate (P.sub.inc) within said underground storage volume, wherein P.sub.inc is maintained at less than a predetermined maximum increase value (PI.sub.max), wherein PI.sub.max is 100 psi/hr, wherein said compressible fluid is hydrogen.

Description

DESCRIPTION OF PREFERRED EMBODIMENTS

(1) Illustrative embodiments of the invention are described below. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

(2) It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

(3) Leached caverns in salt formations are used to store liquids and gases at various pressures. It is found that rapid pressure movements cause failure of the salt cavern structure such as the cavern walls or roof. By limiting the rate of pressure increase or decrease, the cavern structure can be maintained.

(4) Rapid pressure increase or decrease in a salt storage cavern are found to cause stress on the salt cavern walls, leading to wall collapse and roof collapse.

(5) As used herein, the terms net pressure increase rate and net pressure decrease rate are defined as the difference between two pressure measurements that have been made after a lapsed time of one hour. This is not to be interpreted as an instantaneous rate change, i.e. the difference between two pressure measurements that have been made over a very short span of time (e.g. after a lapsed time of less than one minute). Likewise, this is not to be interpreted as a rate change measured over a fraction of an hour, and then interpolated to fit the time span of an entire hour. This is the net pressure change observed between the span of one hour.

(6) In a first embodiment of the present invention, a method of pressure management in an underground storage volume is provided. This method includes storing a compressible fluid in an underground storage volume, and introducing additional compressible fluid into the underground storage volume, thereby producing a net pressure increase rate (P.sub.inc) within the underground storage volume. P.sub.inc is maintained at less than a predetermined maximum increase value (PI.sub.max).

(7) Another embodiment of the current invention includes storing a compressible fluid in an underground storage volume, and removing a portion of the compressible fluid into the underground storage volume, thereby producing a net pressure decrease rate (P.sub.dec) within the underground storage volume, wherein P.sub.dec is maintained at less than a predetermined maximum decrease value (PD.sub.max).

(8) In another embodiment of the current invention, the method includes storing a compressible fluid in an underground storage volume, storing an incompressible fluid in the underground storage volume, and introducing additional incompressible fluid into the underground storage volume, 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).

(9) Another embodiment of the current invention includes storing a compressible fluid in an underground storage volume, storing an incompressible fluid in the underground storage volume, and removing a portion of the incompressible fluid from the underground storage volume, producing a net pressure decrease rate (P.sub.dec) within the underground storage volume, wherein P.sub.dec is maintained at less than a predetermined maximum decrease value (PD.sub.max).

(10) Another embodiment of the current invention includes storing a compressible fluid in an underground storage volume, storing an incompressible fluid in the underground storage volume, introducing additional compressible fluid into the underground storage volume, and concurrently, removing a portion of the incompressible fluid from 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).

(11) Another embodiment of the present invention includes storing a compressible fluid in an underground storage volume, storing an incompressible fluid in the underground storage volume, removing a portion of the compressible fluid from the underground storage volume, and concurrently, introducing additional incompressible fluid into the underground storage volume, thereby producing a net pressure decrease rate (P.sub.dec) within the underground storage volume, wherein P.sub.dec is maintained at less than a predetermined maximum decrease value (PD.sub.max).

(12) Another embodiment of the current invention includes storing a first compressible fluid in an underground storage volume, storing an incompressible fluid in the underground storage volume, removing a portion of the compressible fluid from the underground storage volume, and concurrently, introducing additional incompressible fluid into the underground storage volume, 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).

(13) Another embodiment of the current invention includes storing a first compressible fluid in an underground storage volume, storing an incompressible fluid in the underground storage volume, introducing additional compressible fluid into the underground storage volume, and concurrently, removing a portion of the incompressible fluid from the underground storage volume, producing a net pressure decrease rate (P.sub.dec) within the underground storage volume, wherein P.sub.dec is maintained at less than a predetermined maximum increase value (PD.sub.max).

(14) PI.sub.max may be 100 psi/hr. PI.sub.max may be 75 psi/hr. The underground storage volume may be an underground salt cavern. The compressible fluid may be selected from the group consisting of nitrogen, air, carbon dioxide, hydrogen, helium, and argon. The incompressible fluid may be selected from the group consisting of brine, water, or water slurry.