| abstract |
In an underground formation comprising an evaporitic mineral layer comprising trona, nahcolite, wegscheiderite, or combinations thereof, a method for the solution extraction of an evaporitic mineral from at least one cavity having a mineral-free face, said method comprising: (a) providing a set of at least 3 wells in fluid communication with at least one cavity, said set comprising a first subset of wells of one or more wells operated in injection mode (I), a second subset of wells separated from one or more wells operated in production mode (P); (b) injecting a solvent into the at least one cavity through the first subset operated in injection mode (I) so that the solvent contacts the mineral-free face as the solvent flows through at least one cavity and dissolve in situ at least a portion of the mineral from the free face towards the solvent to form a brine; (c) extracting at least a portion of said brine to the soil surface through the second subset of wells operated in production mode (P); (d) change the mode of operation of at least one well in the assembly after an adequate period of time; and (e) repeat steps (a) through (d); characterized in that: - the set of wells comprises outermost wells that surround the innermost wells, and characterized in that the change of the mode of operation in step (d) for at least some of these more external wells is more frequent than for the innermost wells. |