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Cavern leaching at SPR associated with 2017 oil sales and exchanges

Chojnicki, Kirsten C.

In 2017 small-scale drawdowns at the Strategic Petroleum Reserve (SPR) supported oil sales for the Bipartisan Budget Act of 2015 and the 21st Century Cures Act of 2015 as well as exchanges supporting relief efforts for hurricane Harvey. These drawdowns may affect cavern stability and available drawdowns, thus is important to assess the leaching effects on the cavern shape. Cavern shape estimates from the SANSMIC solution mining code suggest the shapes of 28 caverns were altered in 2017 to varying degrees depending on the total volume of water injected, the initial cavern shape and the distance between the hanging string depth and the oil-brine interface depth. A flaring of the cavern floor occurred in 13 caverns, a geomechanically unfavorable outcome that may require operational changes to preserve cavern integrity. Of the three caverns with post-sale sonars, SANSMIC predictions compared favorably to two but underpredicted the third.