US3578808A

US3578808A - Solution mining method and apparatus

Info

Publication number: US3578808A
Application number: US790935A
Authority: US
Inventors: Byron P Edmonds; Douglas C Ruse
Original assignee: KOLIUM CHEMICALS Ltd
Current assignee: KOLIUM CHEMICALS Ltd
Priority date: 1969-01-14
Filing date: 1969-01-14
Publication date: 1971-05-18
Anticipated expiration: 1988-05-18

Abstract

A method of solution mining soluble subterranean deposits is shown in which a bore hole is cased to the depth equivalent to a desired height of a cavity to be developed in a deposit. Into the cased bore hole a tubing string is introduced with a liner rigidly mounted thereon. The tubing is passed through the casing and into the soluble deposit a substantial distance below the end of the casing set in the deposit. A fixed distance is provided between the end of the tubing and the end of the liner attached thereto. Solvent is then introduced into the soluble deposit and cavity development begun by dissolution of the minerals in the deposit with a suitable solvent. When lateral development of the cavity has proceeded to the desired extent, roof raises are made by moving the tubing string in a vertical direction upward from ground level. The fixed liner moves with the tubing string since it is rigidly mounted thereto. Thus, a fixed mining distance is maintained between the influent point for the solvent entering the soluble deposit and the effluent or withdrawal point. Roof raises can be accomplished in this manner as fixed distances until the liner is finally introduced into the casing by the vertical movement of the tubing toward the ground surface. The apparatus involved in conducting the novel method of the invention is also disclosed.

Description

United States Patent Primary Examiner-Ernest R. Purser Attorney-Chisholm & Spencer ABSTRACT: A method of solution mining soluble subterranean deposits is shown in which a bore hole is cased to the depth equivalent to a desired height of a cavity to be developed in a deposit. Into the cased bore hole a tubing string is introduced with a liner rigidly mounted thereon. The tubing is passed through the casing and into the soluble deposit a substantial distance below the end of the casing set in the deposit. A fixed distance is provided between the end of the tubing and the end of the liner attached thereto. Solvent is then introduced into the soluble deposit and cavity development begun by dissolution of the minerals in the deposit with a suitable solvent. When lateral development of the cavity has proceeded to the desired extent, roof raises are made by moving the tubing string in a vertical direction upward from ground level. The fixed liner moves with the tubing string since it is rigidly mounted thereto. Thus, a fixed mining distance is maintained between the influent point for the solvent entering the soluble deposit and the efiluent or withdrawal point. Roof raises can be accomplished in this manner as fixed distances until the liner is finally introduced into the casing by the vertical movement of the tubing toward the ground surface. The apparatus involved in conducting the novel method of the invention is also disclosed.

PATENTED HAY] 8 I97! SHEET 1 OF 4 FIG. 2

, ma/v nzomowos Doc/6M5 0.2 .55

BY 9 v A'XTORNEYj INVENTOR 5 PATENTED um 8I97| 3578,8053 sum 3 nr 4 FIG. 6

. mvENToR; BYRoA/ R 0M0M05 Dona: 6. Russ ATTORNEY:

" FIGS PATENTED MAY 1- 8 1971 SHEET Q [If 4 WAW/A F 7 INVENTORY BYRON e 50M ouos DOUGLAS 0. e055 A ORNEYS SOLUTION MINING METHOD AND APPARATUS BACKGROUND OF THE INVENTION Many methods have been employed in the past for developing cavities in salt or other soluble rock. Representative of the recent patents issued in this area are U.S. Pat. Nos. 2,787,455, 3,277,654 and 3,088,717. As disclosed in these patents, various methods are employed for adjusting tubing strings and tailpipe liners in developing well cavities. These prior art methods, however, provide for independent movement of tubing strings and liners which is undesirable where it is desired that a fixed distance be maintained between the influent for solvent and the effluent for dissolved material from a solution mining cavity. The inability to precisely determine the position of the liner or the tailpipe or tubing in a subterranean cavity located several thousand feet below ground makes it extremely difficult to precisely determine the extent to which a roof raise will be taken. Furthermore, in developing large cavities in soluble salt deposits. when roof raises are made it is frequently necessary that the tubing be pulled from the hole in order that the casing can be perforated during a roof raise. This latter procedure, of course, requires a considerable amount of development time within a given solution mining cavity for the tubing string to be pulled and for the devices to be set in the casing for the necessary perforation.

THE INVENTION In accordance with the instant invention, mining height may remain constant during the solution mining of a subterranean cavity and the tubing does not have to be pulled from the hole to perforate casings in order to make a roof raise in a development cavity. By virtue of the instant invention, a constant mining height is maintained, that is the influent and effluent points are a fixed vertical distance from each other, and since the tubing goes completely through the liner and is firmly and rigidly affixed to the lining, it is only necessary that the tubing be raised in order to make a roof raise in a development cavity thereby minimizing development time since the necessity of removing drill strings to perforate casing is avoided.

The invention will be more readily understood by reference to the accompanying drawing in which:

FIGS. ll, 2, 3, 4 and of the accompanying drawing show a diagrammatic illustration of the method ofthe instant invention as applied to the solution mining of a KCI deposit having NaCl present therein,

FIG. 6 is illustrative of suitable apparatus to accomplish the method of solution mining disclosed, and

FIG. 7 illustrates the method of the instant invention appliedto two interconnected cavities.

As shown in FIG. 1, a bore hole 1 is drilled to a point near the bottom of a KCl rich-NaCl lean deposit located beneath a KCl rich-NaCl lean deposit which is to be mined. The bore hole I is cased to the upper face of the KCl rich-NaCl lean deposit with casing member 2 utilizing conventional casing techniques. The casing is then utilized to pass a drill pipe or tube 3 down into the deposit 4 rich in KCl' and lean in NaCl, through that deposit and into a KCl lean-NaCl rich deposit 5. The tube 3 is positioned in the deposit 5 near the bottom thereof. Associated with the tube 3 and rigidly attached thereto is a liner 6. This liner is long enough to reach from the casing to a point above the end of. the tube member 3. The distance between the end of the liner 6 and the tube 3 is fixed at the desired distance for solution mining the deposit to be worked. Solution, typically water or weak brine, is then preferably introduced into the liner member 6 in annular space 8 and into the deposit 5 and solution mining of the NaCl rich-KC] lean deposit begins. The dissolved sodium chloridepotassium chloride is removed through the tube 3 and passed to the surface of the ground where it may be discarded, processed for its NaCl content or utilized as feed solvent to KC] rich-NaCl lean deposit.

A suitable cavity is then developed in the deposit in a lateral as well as vertical direction. Lateral development in the deposit may be accomplished by oil or gas padding the roof of the cavity once development has begun. This is readily accomplished, for example, by feeding a liquid immiscible with brine solution to the cavity. Any liquid immiscible with brine and having a density less than the cavity solution may be employed to provide a layer of protective liquid 10 on the roof of the cavity (See FIG. 5). In similar fashion, a liquid immiscible with cavity liquor and having a density greater than the cavity solution can be introduced with the solvent to provide a liquid pad 11 on the floor of the cavity. Obviously, both padding liquids should be such that they do not solubilize the material being mined. In this manner, the initial cavity can be developed in a lateral direction for a substantial distance. Typically, hydrocarbon oils, chlorinated organics and other like materials are utilized for padding purposes.

In FIG. 2, a cavity 7 which has been developed in a lateral direction for some distance has been formed'in the NaCl rich- KCl lean deposit. The tube 3 and its associated liner have been raised so that the end of the liner is now resting on the interface 9 of the

deposits

5 and 4. Solution is continuously introduced through liner 6 to the cavity 7 and with further padding the cavity is extended in a lateral direction for a substantial distance preparatory to mining the KC] rich-NaCl lean strata 4 located above the cavity 7.

I In FIG. 3, the tube 3 and liner 6 have been moved vertically through the NaCl rich-KCI lean deposit. The end of the tube 3 is now located at the base of the KC] rich-NaCl lean deposit and the end of the liner 6 is positioned inside the KCl rich- NaCl lean deposit. Solution for dissolution of the KCI rich- NaCl lean deposit is continuously introduced into the deposit and dissolution of the KC] rich-NaCl lean deposit takes place. The lateral extent of the cavity formed is preferably maintained the same as that established in the NaCl rich-KCL lean deposit in the final roof raise in that deposit and the cavity 7 is now expanded in the vertical direction through the KCI rich- NaCl lean deposit. Solution introduced into the cavity 7 through the liner 6 is removed with dissolved minerals through the tube 3.

FIG. 4 depicts the raising of the roof of the cavity 7 in the KCl rich-NaCl lean deposit by a further movement of the tube 3 and the attached liner 6 upward in the deposit 4. Once again preferably the lateral confines of the cavity are maintained the same and the deposit is mined vertically until the roof of the cavity with the desired lateral dimension reaches the end of the liner 6. Solution is preferably introduced to the cavity 7 and exits through annular space 8 to the surface. Lateral development takes place by roof padding in the conventional manner.

FIG. 5 shows the final roof raise of the cavity 7 to the end of the permanent casing member 2. Once again, the tube 3 and the associated liner 6 have been raised vertically into the casing so that the end of the liner 6 is now within the casing 2.

Tube 3 is still within the cavity and is utilized to remove product fluid therefrom. The incoming solvent for the cavity 7 passes in space 8 through liner 6.

' FIG. 6 shows the apparatus of the instant invention positioned in a casing at its upper end with the tube 3 positioned in the cavity 7 and the associated liner positioned in casing 2. In this apparatus, the tube 3 passes through the liner member 6 and the end of the tube 3 in the cavity 7 is positioned a fixed distance below the one end of liner 6. The liner 6 is rigidly mounted to the tube 3 by means of a spider connection 13 at the base and a similar connection 14 located beneath a liner joint 15. Positioned above the joint 15 is a mandrel packer cup 16. The mandrel packer cup seals the liner assembly against the casing 2 and thus fluid will not flow through the liner above this point. Fluid, leaving the cavity may be passed up through the annulus formed by the outer wall of the tube 3 and the inside wall of the liner 6 though in preferred operation this annulus is used for feed solution to the cavity. The spider connections l3 and 14 can conveniently consist of metal rods, bars, braces and the like which are welded to the outside of the tube 3 and the inside wall of the liner 6. The number and placement of these elements is discretionary, the only important consideration being that they be so arranged that fluid flow through the liner is not prevented. While normal flow to the cavity is for solvent to enter via liner 6 and the annulus 8 and leave via tube 3, once the solution mining cavity is established the flow can be reversed so that the tube 3 serves as the feed conduit and the annulus 8 as the product solution removal conduit.

The exact distance between the end of the liner 6 and the end of the tube 3 that is maintained may be varied considerably without departing from the spirit of the invention. This distance will be detennined by the deposit in which it is desired to employ the invention and the number of roof raises that are desired in developing a cavity in that deposit. In formations where considerable roof collapsing is anticipated, it might be determined that a multiplicity of roof raises are desired prior to establishing the final cavity mining width. In such an instance, the use of a small mining height 2 to feet may be desired. If this should be the case, the liner and tube are fixed so that the distance between their end points in the cavity are within this specified range. In other deposits, the use of greater mining heights and a smaller number of roof raises may be desired. In this case, of course, the mining height is increased accordingly by providing a larger distance between the end ofthe liner 6 in the cavity and the end of the tube 3 in the cavity.

In FIG. 7 the use of the instant invention is depicted in a preferred embodiment utilized in the solution mining of multiple cavities. As shown in FIG. 7, two

cavities

7 and 7 have been established in a KCl lean-NaCl rich deposit and by lateral development these cavities have been connected at and 10. The liner 6' and its connected tube 3' is moved vertically into deposit 4 which is KCl rich-NaCl lean. Solvent flows into the deposit 4' through annulus 8 and dissolution of the KCl rich-NaCl lean deposit is begun. The product fluid is removed preferably through annulus 8 of the liner 6 placed in the cavity 7. In this operation the tube 3 can be plugged to prevent flow therethrough. When the mining of deposit 4 has proceeded to the desired extent the tube 3 and liner 6 of cavity 7 may be moved upwardly in deposit 4 and liquid flow reversed so that solvent is now introduced via annulus 8 to the deposit 4 and product solution is recovered via annulus 8' from the cavity 7. As has been previously stated while it is preferable to employ the annulus 8 or 8' for solvent flow into a deposit the tube 3 can be employed for this purpose.

As will be readily understood the instant invention can be employed to develop a cavity in a KCl lean-NaCl rich deposit positioned adjacent a large cavity located in a KCl rich-NaCl lean deposit to laterally communicate with the cavity through the KO lean-NaCl rich zone. The tube and liner can then be raised in increments to mine the KCl rich-NaCl lean deposit above the KC] lean-NaCl rich zone by operating the existing cavity as a withdrawal cavity for the KCl dissolved as the KCl rich-NaCl lean deposit is mined during movement of the tube and liner vertically through the deposit.

In discussing the invention, particular emphasis has been made to the solution mining of KCl. This has been only for the purpose ofillustration. Indeed, the method described for mining a specific type of KCl deposit has been given as a preferred mode of mining such a deposit. This same deposit can be mined differently with the method of the instant invention without departing from the inventive concept.

Thus, the initial cavity in a KC] rich-NaCl lean deposit can be formed in that deposit, if desired, instead of in the NaCl rich-KCl lean deposit below it as depicted in FIGS. 1 through 5. In such an operation. the method utilized is essentially the same as described above. The tube 3 and its liner 6 are placed in the deposit through borehole I and the casing 2 to the desired depth and the solvent is introduced through tube 3 to solubilize the minerals in the deposit. The cavity solution containing the minerals is removed through the liner 6 between the outer wall of tube 3 and the inner wall of the liner 6. Lateral development of the cavity is undertaken as described above by suitably protecting the floor and roof of the cavity preferably with an inert liquid. If desired, an inert solid can be employed on the floor. Gas padding of the roof in lieu of liquid padding is also within our contemplation. The use of a liquid padding of a cavity roof is described in U.S. Pat. No. 3,096,969 and the method described therein is suitable for use in association with the development of solution mining cavities using the instant invention. The use of solid inerts to protect cavity floor is similarly described in U.S. Pat. No. 3,339,978. Obviously, inert liquids heavier than the cavity solution, can also be employed for floor protection. Maintaining a saturated brine not capable of dissolving any further scale at the cavity floor will also serve adequately as protection and permit lateral development.

' Once the cavity has been extended laterally in the KCl rich- NaCl lean deposit the desired distance, the tube 3 is moved in a vertical direction the desired distance and further development of the cavity in a vertical and, if desired, lateral direction can take place.

In a further embodiment of the instant invention the bore hole 1 may be cased to the interface 9 between

deposits

4 and 5 depicted in FIG. 1. In this instance the roof raises are taken in the same manner as depicted in FIGS. 1, land 3 until the cavity is in communication with the casing member 1. At this point the casing may be used during the mining of the KC] rich-NaCl lean deposit. By conventional perforation techniques the casing may be perforated, the tubing string with the associated liner may be removed and a tube introduced into the bore hole for the introduction of solvent. Solution mining of the KCl-n'ch zone can then proceed in the conventional manner employed with casing permanently affixed in a minable deposit. This further method may be desirable where a communication with a second cavity has been established during the development of the cavity in the NaCl rich-KCl lean deposit and both cavities are being used in the mining operation. In this latter instance one of the cavities is typically utilized as the solvent introduction point for mining the KCl rich-NaCl lean deposit while the second cavity is employed as the withdrawal zone for the KCl product mineral. During operation of multiple cavities of this nature, flow may be reversed from time to time so that a cavity may serve to receive fresh solvent at one time and be utilized to remove product another time.

The ease with which a roof raise can be made utilizing the invention concept herein described can be readily appreciated. '1" he costly procedures formerly employed of perforating casings during cavity development stages of solution mining is eliminated. A constant mining height may now be maintained by vertical adjustment from ground level of the tubing 3 both during development stages of a solution mining operation as well as during development of the product cavity. The apparatus employed can be simply constructed to accomplish the method described and a considerable reduction in the time normally required to develop a solution mining cavity and the consequent saving in costs readily realized.

As used herein in the specification and claims, KCl rich- NaCl lean deposit refers to deposits of KCl and NaCl containing 15 to 60 percent KCl based on the total weight of KCl and NaCl in the deposit. KCl lean-NaCl rich deposits refer to deposits which contain less than 15 percent KCl by weight of the NaCl and KCl therein or which contain no substantial amount of KCl but which are predominantly sodium chloride.

It will be apparent that the method described can be utilized in any solution mining operation involving the dissolution of mineral deposits such as sodium chloride, potassium chloride, magnesium chloride and the like. Thus, while the invention has been described with specific reference to KCl mineral deposits, it is not intended that the method and apparatus be so limited. .So long as a mineral deposit can be mined by solution mining techniques, the method and apparatus herein described may be employed and the advantages obtained. Therefore, it is not intended that the invention be limited to a ing claims.

We claim:

1 l. A method of solution mining a soluble subterranean deposit comprising drilling a borehole into a subterranean deposit, casing said borehole to a depth equivalent to a desired height for a cavity to be developed in said deposit, introducing into said casing a tubing string with a liner rigidly mounted thereon, said tubing string passing through said liner, continuing the introduction of said tubing through the casing and into the soluble deposit to be mined a substantial distance below the end of said casing while maintaining the liner within said casing at one end thereof and a substantial distance below the casing at the other end thereof, providing a fixed distance between the end of the tubing and the end of the liner positioned in the deposit, introducing solvent into the deposit through the liner and removing dissolved minerals through the tubing to thereby form a cavity and adjusting the height of the cavity by moving the tubing vertically away from the cavity to thereby move the liner rigidly mounted thereto the same distance that the tubing is moved.

2. A method of initiating cavity development in a solution mining cavity comprising positioning a fluid conduit for influent solvent in a desired location in a soluble deposit, positi'oning a second conduit for effluent in said soluble deposit at a fixed distance from said influent conduit, said conduits being affixed to each other and one conduit surrounding at least a portion of the other conduit, the ends of both conduits being a fixed distance from each other, introducing solvent through the conduit for influent solvent capable of dissolving said soluble deposit, removing solution from said second conduit, to thereby establish a cavity in said soluble deposit, repositioning both of said conduits when the cavity has reached a predetermined size by raising one of said conduits to thereby increase the height of the roof of said cavity and to thereby raise the other conduit afiixed to the one which is raised.

3. A method of developing a solution mining cavity in a subterranean mineral deposit comprising boring a hole into said deposit, casing said deposit at a desired height for a solution mining cavity to be developed, introducing through said casing at least two fluid conduits rigidly affixed to each other so that when one conduit is moved in a vertical direction the other conduit must move with it, one of said conduits being circumferentially disposed around at least a part of the other conduit, the lower end of said two conduits being spaced a fixed distance from each other, positioning the lower ends of both conduits a substantial distance below the end of said casing, introducing fluid capable of dissolving the mineral content of the said deposit into the outer conduit and withdrawing product solution from the inner conduit, developing a cavity by dissolution of minerals in a lateral direction to a desired distance, raising both of said conduits simultaneously to a higher level in said deposit while maintaining the distance between their lower ends constant by raising one of the con duits, dissolving further quantities of minerals at the new position of said conduits until the desired mineral content has been removed from said deposit in the new position.

4. Apparatus for developing a solution mining cavity comprising a first fluid conduit, a second fluid conduit having a diameter greater than said first ,fluid conduit, means for mounting said second conduit in a fixed engagement to said first conduit to thereby form a unit whereby one conduit cannot be moved without the other conduit being moved, both conduits being constructed and arranged so as to be capable of being passed into a cased borehole, means associated with said second conduit to seal said conduit to a borehole casing, said first and second conduits being spaced from each other in a vertical direction to provide a fixed distance between their lower ends when positioned in a borehole.

5. A method of solution mining a soluble subterranean deposit comprising drilling a borehole into a subterranean deposit, casing said borehole to a depth equivalent to a desired height for a cavity to be developed in said deposit, introducing into said casing tubing having a liner rigidly affixed thereto so that the liner moves when said tubing moves, the liner and tubing being so arranged in fixed relationship that the lower ends of each terminate at a fixed distance from each other thereby providing a vertical mining height between their ends, passing the said tubing through the said casing and into the soluble deposit while maintaining at least a portion of the attached liner within said casing, introducing solvent for the minerals in said deposit into the liner and removing dissolved minerals through said tubing.

6. A method of solution mining a KC] rich-NaCl lean deposit positioned above a KC] lean-NaCl rich deposit, comprising providing a borehole through said KC] rich-NaCl lean deposit and into said KCl lean-NaCl rich deposit, casing said borehole to at least the upper portion of said KC] rich-NaC] lean deposit, introducing through said casing a tube having rigidly mounted thereto a liner defining a conduit between its inner wall and the outer wall of said tube, the tube and liner being so arranged in their mounting relationship that the end of the tube is a fixed vertical distance below the end of said liner, positioning the ends of the tube and liner in said KC] lean-NaCl rich deposit while maintaining a portion of the liner within said casing, introducing solvent into said KC] lean-NaCl rich deposit through said liner and removing solution through said tube to thereby form a cavity in the KC] lean-NaCl rich deposit, developing said cavity to a desired lateral distance, moving said tube and thereby moving its associated liner upwardly when the cavity has developed the desired lateral distance, continuing dissolution of the KC] lean-NaCl rich deposit while the tube and liner are in their new position to a desired lateral distance, and continuing the raising of the tube and liner and lateral cavity development in this manner until the end of the tube is positioned within the KCl rich-NaCl lean deposit.

7. A method of solution mining KC] from a KC] rich-NaCl lean deposit located above a KCl lean-NaCl rich deposit comprising drilling a borehole through said KCl rich-NaCl lean deposit and into said KC] lean-NaCl rich deposit, casing said borehole to a point near the upper surface of said KC] rich- NaCl lean deposit, passing a tube having a liner fixedly attached thereto through the cased borehole a sufficient distance to thereby position the lower ends of both the tube and the associated liner in the KC] lean-NaCl rich deposit while positioning the upper end of the liner inside the casing, the tube and liner being so arranged that the end of the tube is positioned below the end of the liner in said deposit a fixed distance, introducing a solvent suitable for dissolution of the mineral content of said KC] lean-NaC] rich deposit through the liner to thereby dissolve the minerals in'said KC] lean- NaCl rich deposit, withdrawing dissolved minerals through said tube, laterally developing a cavity in said KC] lean-NaCl rich deposit to a desired degree, increasing the height of the cavity so developed by raising the tube vertically in increments and thereby raising its associated liner the same increments to thereby ultimately extend the cavity into said KC] rich-NaCl lean deposit, and recovering the mineral content of the KC] rich-NaCl lean deposit as a solution through said tube.

8. The method of claim 7 wherein said borehole is cased to a point near the interface between said KC] rich-NaCl lean deposit and said KC] lean-NaCl rich deposit.

9. The method of claim 7 wherein the initial cavity is developed in a lateral direction by padding the roof of the cavity with a fluid immiscible with the cavity solution.

10. The method of claim 7 wherein said solvent is introduced through said tube and the said dissolved minerals are withdrawn through said liner.

1]. A method of solution mining KC] from a KC] rich-NaC] lean deposit positioned above a KC] lean-NaCl rich deposit wherein a first cavity is positioned adjacent said KCl lean- NaCl rich deposit comprising drilling a borehole into said KC] lean-NaCl rich deposit adjacent to said first cavity, casing the borehole to at least the top of the KC] rich-NaCl lean deposit, passing a tube having a liner fixedly mounted thereto and around said tube through said borehole a sufficient distance to position the lower ends of both the tube and the liner in the KC] lean-NaCl rich deposit while maintaining the upper end of the liner inside of said casing, the tube and liner being so arranged that their lower ends are spaced apart from each other a fixed distance, introducing solvent suitable for dissolution of the mineral content of said KCl lean-NaCl rich deposit through the liner to thereby dissolve the minerals in said deposit, withdrawing dissolved minerals through said tube, laterally developing a cavity in said KC] lean-NaCl rich deposit until the cavity being developed communicates with said first cavity, withdrawing dissolved minerals from said first cavity when the cavity being developed communicates therewith while using the cavity being developed as an injection cavity for solvent, periodically raising the tube and thereby raising the associated liner in the cavity being developed a fixed distance to increase the height of the said injection cavity, continuing the dissolution of the mineral con tent of the KCl lean-NaCl rich deposit, continuing periodic raising of the tube and thereby the liner until the ends of the tube and liner are in the KO rich-NaCl lean deposit and dissolving the mineral content of the KCl rich-NaCl lean deposit.

12. The method of claim 11 wherein the flow of solvent in the two cavities is reversed so that solvent flows into the existing cavity and dissolved minerals are withdrawn from said cavity being developed.

223 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,578,808 Dated May 18, 1971 lnvenunis) yron P. Edmonds and Douglas C. Ruse It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading, ssignee's name Kolium" should be "Kalium" Signed and sealed this 31st day of August 1971.

(SEAL) Attest:

EDWARD MFLETGHER JR. ROBERT GOTTSCI IALK Attesting gfficer Acting Commissioner of Patents

Claims

1. A method of solution mining a soluble subterranean deposit comprising drilling a borehole into a subterranean deposit, casing said borehole to a depth equivalent to a desired height for a cavity to be developed in said deposit, introducing into said casing a tubing string with a liner rigidly mounted thereon, said tubing string passing through said liner, continuing the introduction of said tubing through the casing and into the soluble deposit to be mined a substantial distance below the end of said casing while maintaining the liner within said casing at one end thereof and a substantial distance below the casing at the other end thereof, providing a fixed distance between the end of tHe tubing and the end of the liner positioned in the deposit, introducing solvent into the deposit through the liner and removing dissolved minerals through the tubing to thereby form a cavity and adjusting the height of the cavity by moving the tubing vertically away from the cavity to thereby move the liner rigidly mounted thereto the same distance that the tubing is moved.

2. A method of initiating cavity development in a solution mining cavity comprising positioning a fluid conduit for influent solvent in a desired location in a soluble deposit, positioning a second conduit for effluent in said soluble deposit at a fixed distance from said influent conduit, said conduits being affixed to each other and one conduit surrounding at least a portion of the other conduit, the ends of both conduits being a fixed distance from each other, introducing solvent through the conduit for influent solvent capable of dissolving said soluble deposit, removing solution from said second conduit, to thereby establish a cavity in said soluble deposit, repositioning both of said conduits when the cavity has reached a predetermined size by raising one of said conduits to thereby increase the height of the roof of said cavity and to thereby raise the other conduit affixed to the one which is raised.

3. A method of developing a solution mining cavity in a subterranean mineral deposit comprising boring a hole into said deposit, casing said deposit at a desired height for a solution mining cavity to be developed, introducing through said casing at least two fluid conduits rigidly affixed to each other so that when one conduit is moved in a vertical direction the other conduit must move with it, one of said conduits being circumferentially disposed around at least a part of the other conduit, the lower end of said two conduits being spaced a fixed distance from each other, positioning the lower ends of both conduits a substantial distance below the end of said casing, introducing fluid capable of dissolving the mineral content of the said deposit into the outer conduit and withdrawing product solution from the inner conduit, developing a cavity by dissolution of minerals in a lateral direction to a desired distance, raising both of said conduits simultaneously to a higher level in said deposit while maintaining the distance between their lower ends constant by raising one of the conduits, dissolving further quantities of minerals at the new position of said conduits until the desired mineral content has been removed from said deposit in the new position.

4. Apparatus for developing a solution mining cavity comprising a first fluid conduit, a second fluid conduit having a diameter greater than said first fluid conduit, means for mounting said second conduit in a fixed engagement to said first conduit to thereby form a unit whereby one conduit cannot be moved without the other conduit being moved, both conduits being constructed and arranged so as to be capable of being passed into a cased borehole, means associated with said second conduit to seal said conduit to a borehole casing, said first and second conduits being spaced from each other in a vertical direction to provide a fixed distance between their lower ends when positioned in a borehole.

6. A method of solution mining a KCl rich-NaCl lean deposit positioned above a KCl lean-NaCl rich deposit, comprising providing a borehole through said KCl rich-NaCl lean deposit and into said KCl lean-NaCl rich deposit, casing said borehole to at least the upper portion of said KCl rich-NaCl lean deposit, introducing through said casing a tube having rigidly mounted thereto a liner defining a conduit between its inner wall and the outer wall of said tube, the tube and liner being so arranged in their mounting relationship that the end of the tube is a fixed vertical distance below the end of said liner, positioning the ends of the tube and liner in said KCl lean-NaCl rich deposit while maintaining a portion of the liner within said casing, introducing solvent into said KCl lean-NaCl rich deposit through said liner and removing solution through said tube to thereby form a cavity in the KCl lean-NaCl rich deposit, developing said cavity to a desired lateral distance, moving said tube and thereby moving its associated liner upwardly when the cavity has developed the desired lateral distance, continuing dissolution of the KCl lean-NaCl rich deposit while the tube and liner are in their new position to a desired lateral distance, and continuing the raising of the tube and liner and lateral cavity development in this manner until the end of the tube is positioned within the KCl rich-NaCl lean deposit.

7. A method of solution mining KCl from a KCl rich-NaCl lean deposit located above a KCl lean-NaCl rich deposit comprising drilling a borehole through said KCl rich-NaCl lean deposit and into said KCl lean-NaCl rich deposit, casing said borehole to a point near the upper surface of said KCl rich-NaCl lean deposit, passing a tube having a liner fixedly attached thereto through the cased borehole a sufficient distance to thereby position the lower ends of both the tube and the associated liner in the KCl lean-NaCl rich deposit while positioning the upper end of the liner inside the casing, the tube and liner being so arranged that the end of the tube is positioned below the end of the liner in said deposit a fixed distance, introducing a solvent suitable for dissolution of the mineral content of said KCl lean-NaCl rich deposit through the liner to thereby dissolve the minerals in said KCl lean-NaCl rich deposit, withdrawing dissolved minerals through said tube, laterally developing a cavity in said KCl lean-NaCl rich deposit to a desired degree, increasing the height of the cavity so developed by raising the tube vertically in increments and thereby raising its associated liner the same increments to thereby ultimately extend the cavity into said KCl rich-NaCl lean deposit, and recovering the mineral content of the KCl rich-NaCl lean deposit as a solution through said tube.

8. The method of claim 7 wherein said borehole is cased to a point near the interface between said KCl rich-NaCl lean deposit and said KCl lean-NaCl rich deposit.

11. A method of solution mining KCl from a KCl rich-NaCl lean deposit positioned above a KCl lean-NaCl rich deposit wherein a first cavity is positioned adjacent said KCl lean-NaCl rich deposit comprising drilling a borehole into said KCl lean-NaCl rich deposit adjacent to said first cavity, casing the borehole to at least the top of the KCl rich-NaCl lean deposit, passing a tube having a liner fixedly mounted thereto and around said tube through said borehole a sufficient distAnce to position the lower ends of both the tube and the liner in the KCl lean-NaCl rich deposit while maintaining the upper end of the liner inside of said casing, the tube and liner being so arranged that their lower ends are spaced apart from each other a fixed distance, introducing solvent suitable for dissolution of the mineral content of said KCl lean-NaCl rich deposit through the liner to thereby dissolve the minerals in said deposit, withdrawing dissolved minerals through said tube, laterally developing a cavity in said KCl lean-NaCl rich deposit until the cavity being developed communicates with said first cavity, withdrawing dissolved minerals from said first cavity when the cavity being developed communicates therewith while using the cavity being developed as an injection cavity for solvent, periodically raising the tube and thereby raising the associated liner in the cavity being developed a fixed distance to increase the height of the said injection cavity, continuing the dissolution of the mineral content of the KCl lean-NaCl rich deposit, continuing periodic raising of the tube and thereby the liner until the ends of the tube and liner are in the KCl rich-NaCl lean deposit and dissolving the mineral content of the KCl rich-NaCl lean deposit.