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The United States of America As Represented by the Secretary of

The United States of America, As Represented by the Secretary of the Interior

William C Larson

Edward T Wood

Robert F Snyder

Donald W Dareing

Roger J Morrell

Robert D Schmidt

A method and the necessary equipment to form horizontal cased and perforated drainholes for an underground, in situ leach mining operation. After a vertical hole has been formed and cased in the earth, horizontal drainholes are to be drilled from below its casing. The depth and thickness of the ore body which is to be recovered is determined. Following this, the proper whipstock orientation is computed and the horizontal drainhole is whipstocked and drilled from above the ore bed into it. A flexible casing, such as Coflexip pipe, is used to case the drainholes. Perforations or slots are provided for in these casings before they are put in the earth. A special retrievable cement plug, basket, and one-way valve are used to control and direct the flow of cement to the volume between the outside of the juncture at the casings.

Method and apparatus to complete horizontal drain holes

A method of drilling and completing multiple branch wells extending from a main generally vertical hole. This invention finds its primary applicability in in situ leach mining of deep (500 to several thousand feet) lying ore bodies such as uranium, copper, etc. Initially, the main generally vertical hole is drilled, cased, and cemented. Whipstock drilling guides are placed to extend downwardly and outwardly from the bottom of the casing for this hole and cemented in place. These guides are the same in number as the branch holes to be drilled. In addition, the well bore casing contains an indexing dog just above the whipstock drilling guide. The actual drilling of the branch wells is accomplished with a floating index collar and a drill bit assembly which runs therewith. The indexing dog is fixed in the main hole and engages the indexing collar so that the drill bit is oriented to drill into one of the whipstock drilling guides. After a particular branchis drilled, the collar and bit are retrieved from the main hole. The bit is then placed in another hole of the collar and the combination reinserted in the main hole where it again engages the indexing dog and allows drilling of another branch well. After all branch wells are drilled, they are cased with a flexible casing, like fiberglass, cemented and selectively perforated. If the well is a liquid recovery well, a pump is placed at the bottom of the main vertical hole casing near where it joins the branch wells.

Multiple branch completion with common drilling and casing template

A multiple branch well for use with in situ leach mining of deep lying ore bodies. The branch wells may be formed by a method disclosed in a related invention. Each well may have two branches one of which is a producer well and one an injector well. Internally of the main casing from which the two branch casings extend are--from the lower end up--a packer unit, a tubing hanger, and a wireline retrievable hydraulically generated pump. The packer and tubing hanger serve their conventional function of, respectively, blocking the flow of leach fluids and holding the branch tubular casing in place within the main casing. The hydraulic pump joins the tubular casings to maintain a constant ratio of produced fluid to injected fluid. This pump is operated by a pressurized fluid source. Since it is retrievable and hydraulically operated, the pump can be brought to the surface for any repairs or maintenance and it requires less surface plumbing with no down hole electrical power.

Multiple branch well containing one producer and one injector well

An improved method of in situ mining of a mineral bearing stratum. The method comprises drilling alternating rows of vertical injection and recovery wells to the depth of an aquiferrous mineral bearing stratum. Two horizontal branches are drilled at the bottom of each injection and recovery well. The horizontal branches are substantially parallel to one another and lie within the mineral bearing stratum. Leachant fluid is pumped under pressure into the injection wells to dissolve the minerals contained in the stratum. Leachant fluid containing the dissolved minerals is pumped out through the recovery wells. The method of the present invention requires substantially less drilling and pipe for extracting minerals from a given volume of a mineral bearing stratum and results in more constant mineral extraction rates than conventional techniques.

Method of in situ mining

A method and apparatus for in-situ leach mining which utilizes multiple dhole branch wells whipstocked off a single main generally vertical well. Initially the vertical well is drilled into the earth so that it may intersect the ore zone of material to be recovered. The vertical well may be cased and cemented after drilling. Thereafter from this same well a plurality of branch wells are whipstocked or drilled which intersect the vertical well at an angle from about 2 degrees to 60 degrees. These branch wells extend into the ore zone. A submersible pump and drop pipe are placed in the main well and at some point below the intersection of the main well with the branch wells a packer is placed around the drop pipe. The drop pipe carries solutions to the surface from the pump. Leaching solutions are forced or injected in the main well in the volume between the exterior surface of the drop pipe and well hole or casing so that upon encountering the branch wells and packer their solutions are forced into the branches and out into the ore body. After exiting near the opened ends (or well screens) of the branch wells into the ore zone, the leaching solution dissolves the mineral values and the solution flow with its entrapped minerals is forced by the action of the pump through the ore zone towards the vertical well, where the solution is pumped up to the surface, via the inner drop pipe.

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Bloomington, MN, United States of America

William C Larson