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Focused Dissolution and Collapse

  Detailed cross section between two closely spaced wells, in an area of complex salt dissolution. Location shown in general map of the Permian Basin.

In areas where hydrologic complexities are found, salt dissolution may be irregular and complex. Focused dissolution may remove salt from one small area and leave it intact in an adjacent area. In cross section focused dissolution and collapse results in steeper-than-regional dips and irregular unit thickness. Focused dissolution and irregular subsidence favors creation of abundant and potentially well-connected fracture systems (Goldstein and Collins, 1984; Collins and Luneau, 1986). Thicker intervals of permeable residue strata and more fracturing will focus flow and propagate further irregular dissolution patterns.

In the Palo Duro Basin, cored collapse breccia (a) from the floor of a small cavern, DOE Stone and Webster Sawyer core, 446 ft below datum. Strata overlying a large cavern collapse breccia have been fractured (b). These fabrics are interpreted as a result of formation and subsequent collapse of natural caverns in the salt in an area of complex salt dissolution over a structural positive in the Rolling Plains, an area of recognized salt-dissolution collapse (Baumgardner and others, 1982).

Timing of Salt Dissolution