Solution mining method with elongate sump

A solution mining method for recovering a target material from an at-depth at least partially soluble target layer, the target layer comprising salt and the target material, the target layer overlying a salt layer, the method comprising the steps of:

• a. drilling a first well downwardly to the salt layer and then generally horizontally for a distance through the salt layer at or below an interface between the target layer and the salt layer, thereby forming a horizontal leg terminating at an end position, wherein the horizontal leg is drilled in a curved orientation;
• b. drilling a second well downwardly to the horizontal leg at or near the end position of the horizontal leg of the first well;
• c. injecting a sump formation fluid comprising heated water through the horizontal leg, thereby dissolving a portion of the salt layer adjacent the horizontal leg and forming an elongate sump;
• d. drilling at least one target layer well downwardly to the target layer and then generally horizontally through the target layer, connecting with the elongate sump;
• e. providing an injection fluid of suitable chemical composition;
• f. heating the injection fluid to a desired temperature selected to bring the target layer temperature to a desired target layer temperature;
• g. injecting the injection fluid through the at least one target layer well toward the elongate sump to bring the target layer temperature to the desired target layer temperature and at least partially dissolve the target layer,
• h. allowing the target layer to at least partially dissolve to form a target layer brine comprising the target material;
• i. allowing liberated waste salt to separate out of the target layer during dissolution;
• j. allowing at least a portion of the waste salt and insoluble materials from the target layer to accumulate in the elongate sump;
• k. producing the target layer brine and at least a portion of the injection fluid through the second well;
• l. recovering the target material from the target layer brine at surface;
• and
• m. reheating and reinjecting at least a certain amount of the produced target layer brine and the produced injection fluid to further dissolve the target layer, wherein the amount of the reheated and reinjected target layer brine is determined by a need to control flow rates in the target layer and the temperature from the second well.