Experimental studies of oil withdrawal from salt cavities via fresh-water injection
The US Strategic Strategic Petroleum Reserve (SPR) program coordinates the storage of crude oil in underground salt caverns. Oil removal from these caverns will be accomplished by injecting water into a brine volume located beneath the oil, buoyantly displacing the oil upwards, where it will then be recovered through a production pipe located near the top of the cavern. The critical question was whether or not the crude oil would protect the salt walls from dissolution upon exposure to unsaturated brine following oil/brine interface passage. These oil/brine/salt interactions were experimentally investigated in the laboratory. Cylindrical cavities were created by machining (hollowing-out) salt cores from one end, leaving the circular wall and bottom as an integral piece. In each of four separate experiments, a salt cavity was placed vertically in a pressure vessel and its interior filled with crude oil overlying a saturated-brine picket. The vessel was sealed and pressurized to actual SPR-cavern pressure. Fresh water was injected down a tube and into the brine pocket, displacing the coil upwards, where it was recovered from the cavity through a second (production) tube near the top of the vessel. A traversable gamma-beam densitometer was positioned above the initial saturated-brine/oil interface and was used as a non-intrusive diagnostic to define the presence, or absence, of salt dissolution (cavity shape change) during the transient oil-withdrawal process. Such measurements showed the occurrence of salt-wall recession following interface passage in all tests, i.e., crude-oil adherence, and/or penetration, at the salt wall failed to protect the salt from dissolution upon its exposure to unsaturated brine. Measured post-test cavity shapes corroborated the transient results. Both transient and steady-state measurements were found to be in good agreement with numerical predictions. 15 references, 16 figures, 1 table.
- Research Organization:
- Sandia National Labs., Albuquerque, NM (USA)
- DOE Contract Number:
- AC04-76DP00789
- OSTI ID:
- 5168498
- Report Number(s):
- SAND-83-0347; ON: DE84010106
- Resource Relation:
- Other Information: 4
- Country of Publication:
- United States
- Language:
- English
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