Patent Application
20220195858
The embodiments described herein relate generally to solution mining and, more particularly, to a method utilizing downhole flow control via a sliding sleeve or other downhole flow control devices for solution mining. Specifically, the method includes solution mining of a soluble mineral at depth using a technique that allows for the control of the solvent flow through multiple locations within a solution mining injection well.
Solution mining is a mining method in which the mining of desired minerals is achieved by the injection of a water, or a lean water solution, underground and into a geological formation that contains a desired soluble mineral in a grade concentration that has been determined to be economically feasible for solution mining. The mineral is dissolved into the water, and the rich water solution flows by pump pressure back to the surface and into a mineral recovery processing plant. A solution mining project can be, and has been, an alternative to conventional underground mining projects in which miners and mining equipment work underground to extract and bring to the surface ore in a solid form.
Many solution mining designs utilize casing perforations to direct the location of where the solvent will be injected into the mineralized zone to facilitate the solution mining. Additional perforations are added as required using electric wireline operations and casing perforation tools.
With the continued development of oil and gas horizontal well drilling techniques, horizontal boreholes are being utilized to facilitate solution mining. Some horizontal solution mining designs utilize intersecting horizontal wellbores or multiple intersecting wellbores. However, in the case of multiple intersecting wellbores, the operator does not have the flexibility to adjust the solvent flow through each intersecting borehole.
Therefore, what is needed is a method for controlling the downhole flow of solvent injection for recovery of solution mined minerals, even in multiple intersecting wellbores.
Some embodiments of the present disclosure include a method for controlling downhole fluid flow in multi-lateral solution mining may include forming a solution mining production well with a plurality of horizontal laterals drilled from a surface to connect and intersect with a horizontal or vertical injection well; and installing a downhole flow control device at the intersection of the horizontal or vertical injection well and each of the horizontal laterals. The downhole flow control device may be capable of being adjusted to distribute injection flow as desired through the horizontal laterals. The downhole flow control device may be a sliding sleeve capable of ranging from fully opened, partially opened at varying degrees, to fully closed to control flow from the injection well into multiple locations within the mineralized zone.
The detailed description of some embodiments of the invention is made below with reference to the accompanying figures, wherein like numerals represent corresponding parts of the figures.
In the following detailed description of the invention, numerous details, examples, and embodiments of the invention are described. However, it will be clear and apparent to one skilled in the art that the invention is not limited to the embodiments set forth and that the invention can be adapted for any of several applications.
The method of the present disclosure may be used to facilitate and improve the recovery of solution mined minerals by allowing downhole flow control of injected solvents and may comprise the following elements. This list of possible constituent elements is intended to be exemplary only, and it is not intended that this list be used to limit the device of the present application to just these elements. Persons having ordinary skill in the art relevant to the present disclosure may understand there to be equivalent elements that may be substituted within the present disclosure without changing the essential function or operation of the device.
The various elements of the present disclosure may be related in the following exemplary fashion. It is not intended to limit the scope or nature of the relationships between the various elements and the following examples are presented as illustrative examples only.
As used herein, the following terms and nomenclature have the following definitions:
Solution mine: the wellfield pumping, equipment, and underground caverns as required for solution mining.
Injection well: a well drilled from the surface to the mineralized geological formation at depth to facilitate the injection of a solution, water, or solvent to dissolve a desired mineral into solution.
Injection solution, injection water, or solvent: the water or water solution leaving the process plant and pumped to the wellfield injection wells to facilitate the solution mining.
Downhole flow control device: a device installed within the injection well that can be adjusted as desired to vary the flow through the device into the mineralized geological formation to facilitate the solution mining.
Production well: a well drilled from the surface to the mineralized geological formation to facilitate the flow of the dissolved mineral solution to the surface and subsequently to the processing plant.
Horizontal lateral borehole or lateral: a horizontal borehole drilled along the mineralized geological formation which creates a flow path between the injection well and the production well. Some designs utilize multiple laterals to enhance the distribution of the solvent and to increase the quantity of mineral dissolved into solution.
Production solution or production brine: the water solution containing dissolved materials leaving the wellfield production wells and returning to the process plant for mineral recovery.
Oil and gas horizontal drilling technology: well drilling technology developed by oil and gas drilling companies to steer a wellbore from vertical to horizontal and to direct the wellbore horizontally along a specific geological zone.
Sliding sleeve flow control tool: oil and gas well completion component, such as that shown in
Magnetic ranging tool: a specialized oil and gas well drilling technique in which a magnetic source is placed as a target within the targeted wellbore and a magnetic sensor is placed near the drill bit in the drill string within the second wellbore. Using the magnetic source as a beacon, the well is directionally drilled toward the highest magnetic reading. This technique allows two independent boreholes to be drilled in a manner that they intersect at the magnetic source.
By way of example, and referring to
As shown in
When a downhole flow control device is not in place, the horizontal laterals with the lowest pressure drops will accept injection flow through the lateral at higher rates than the other laterals, causing the laterals with a higher flow rate to grow larger than the other laterals, thus further reducing the pressure drop for the other laterals. Over time, one (or possibly several) lateral(s) will develop as the predominate flow path through the solution mining cavern. As this occurs, the injection flow through the other laterals is reduced and the overall soluble mineral recovery of the solution mining system will be significantly reduced. On the other hand, when the method of the present disclosure is practiced and a downhole flow control device is in place, the flow through each lateral can be adjusted as necessary to distribute the injection flow through each individual lateral as desired by the solution mining operator.
The downhole flow control device used in the method of the present disclosure may comprise any suitable device for controlling the flow. For example, as shown in
The method of the present disclosure may comprise first drilling a horizontal injection well 22 and installing a steel liner with a flow control device(s) and then drilling a multi-lateral production well 18. The flow control device may be installed within the horizontal borehole steel liner of the injection well with a spacing as desired by the solution mining well operator. A magnetic ranging tool, which serves as a directional beacon to guide the horizontal drilling of the intersecting wellbore, may be temporarily installed in the injection well 22 as a target to facilitate the intersection of the horizontal injection well 22 and each of the production well laterals. Advantageously, whenever possible, the intersecting lateral may be drilled about 1 to about 3 meters below the horizontal injection well 22 position, and the final intersection may be achieved by solution mining from the lateral up to the horizontal injection well tool position. As a result, a 1 to 3 meter deep sump may be formed at each injection location, wherein the sumps may allow any insoluble material in the ore zone immediately above the injection point to settle within the sump, reducing the insoluble materials' impact on the downhole low control devices.
As the solution mining cavern is placed into service, a baseline wireline temperature log of the horizontal injection well 22 may be performed. During operation of the solution mining cavern, periodic temperature logs of the horizontal injection well 22 may be performed. If the flow distribution is adequate, the temperature distribution through the injection laterals should be similar to the baseline line temperature log. If the temperature log indicates an anomalous temperature profile, then a downhole injection flow measurement may be performed, wherein the flow measurement may comprise a wireline or coiled tubing E-line flow meter tool that measures the injection flow at the tool's location. As the tool passes each downhole flow control device, the flow may be reduced by the amount of flowing going through the lateral that was passed. At the completion of the flow survey, the flow rate through each lateral may be determined. Using the results of the flow survey, the downhole flow control devices may be adjusted, as necessary, to distribute the injection flow across the laterals, as desired.
If desired or necessary, the method of the present disclosure may further comprise directing injection flow through on to multiple laterals as desired. For example, the operator may wish to focus the injection flow down a single lateral to enhance cavern development or cavern maintenance. In another example, at the end of the solution mining cavern life, the operator may wish to direct the injection flow through the outside laterals to increase the quantity of the desired mineral dissolved into solution.
The above-described embodiments of the invention are presented for purposes of illustration and not of limitation. While these embodiments of the invention have been described with reference to numerous specific details, one of ordinary skill in the art will recognize that the invention can be embodied in other specific forms without departing from the spirit of the invention. Thus, one of ordinary skill in the art would understand that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims.
