A well completion method for in-situ leaching drilling

Abstract

The present invention belongs to the technical field of in-situ leaching uranium mining, and specifically relates to a well completion method for in-situ leaching drilling. The well completion method for in-situ leaching drilling provided by the present invention uses a high-pressure hydraulic sandblasting device to implement the method. The high-pressure hydraulic sandblasting device includes a high-pressure hydraulic jet spray gun, a sand mixing skid, and a booster skid. The method includes the following steps: After cementing, lower the high-pressure hydraulic jet spray gun into the casing for interval cutting to obtain interval slits; lower an internal filter into the casing, with the bottom of the filter flush with the lowermost end of the interval slits and the top of the filter flush with the uppermost end of the interval slits. In the well completion method of the present invention, the entire slit cutting operation only takes 3.0 - 4.0 h, greatly improving the construction efficiency compared with the existing mechanical cutting process which takes 8.0 - 14.0 h.

Description

Technical Field

[0001] The present invention belongs to the technical field of in-situ leaching uranium mining, and particularly relates to a well completion method for in-situ leaching drilling. Background Art

[0002] Drilling is a key link in the in-situ leaching uranium mining process, and the well completion process of drilling directly affects the leachate concentration, leaching efficiency and mining cost. The drilling in the traditional in-situ leaching uranium mining process usually adopts a large-diameter gravel-packed structure. The well completion process is as follows: piping is completed on the surface, a sand settling pipe, an annular outer skeleton filter and a casing are lowered into the open hole, gravel is filled in the filter section, and cementing is completed by positive grouting. However, problems such as bridging are likely to occur during the gravel filling process, which affects the gravel filling quality and thus the normal operation of the drilling.

[0003] With the development of technology, the drilling in the in-situ leaching uranium mining process gradually adopts the method of in-well cutting to achieve well completion. The main process is as follows: the ore layer is cut by a mechanical cutting tool (such as a cutting tool) to establish a connection with the ore layer, and then an in-built filter is lowered to complete well completion. Although this process can ensure the quality of well completion, the well completion efficiency is low. Summary of the Invention

[0004] In view of this, the present invention provides a well completion method for in-situ leaching drilling, which improves the well completion efficiency while ensuring the well completion quality.

[0005] In order to solve the above technical problems, the present invention provides a well completion method for in-situ leaching drilling, which is implemented by a high-pressure hydraulic sandblasting device. The high-pressure hydraulic sandblasting device includes a high-pressure hydraulic jet spray gun, a sand mixing skid and a booster skid. The method includes the following steps:

[0006] After cementing, the high-pressure hydraulic jet spray gun is lowered into the casing for interval cutting to obtain interval cut slots;

[0007] An in-built filter is lowered into the casing, the bottom of the filter is flush with the lowermost end of the interval cut slots, and the top of the filter is flush with the uppermost end of the interval cut slots.

[0008] Preferably, the pressure of the high-pressure hydraulic jet spray gun is 32 - 40 MPa, and the flow rate of the high-pressure hydraulic jet spray gun is 260 - 450 L / min.

[0009] Preferably, the length of the high-pressure hydraulic jet spray gun is 600 - 640 mm, and the diameter of the high-pressure hydraulic jet spray gun is 110 - 120 mm.

[0010] Preferably, the high-pressure hydraulic jet spray gun includes nozzles arranged at the top and located in the same plane, and the number of the nozzles is 1 - 4;

[0011] The diameter of the nozzle is 2.5 to 4.5 mm; the product of the included angle between two adjacent nozzles and the number of nozzles is 360°.

[0012] Preferably, the width of any single slit in the spaced slits is 5 to 9 mm; the distance between any two single slits in the spaced slits is 90 to 110 mm.

[0013] Preferably, the total length of the spaced slits is 5 to 11 m.

[0014] Preferably, the cementing includes the following steps: lowering a casing into the open hole and injecting cement slurry reversely through the grouting holes reserved at the bottom of the casing.

[0015] Preferably, the diameter of the open hole is 210 to 220 mm, and the depth of the open hole is 334 to 429 m.

[0016] Preferably, the lowering depth of the filter is 321.0 to 423.5 m.

[0017] The present invention provides a well completion method for in-situ leaching drilling. The method is implemented by using a high-pressure water jet sandblasting device. The high-pressure water jet sandblasting device includes a high-pressure water jet spray gun, a sand mixing skid, and a pressure boosting skid. The method includes the following steps: After cementing, lowering the high-pressure water jet spray gun into the casing for spaced cutting to obtain spaced slits; lowering an internal filter into the casing, with the bottom of the filter flush with the lowermost end of the spaced slits and the top of the filter flush with the uppermost end of the spaced slits. The present invention uses a high-pressure water jet sandblasting device to cut slits in the casing and the cementing layer, and establish a hydraulic connection between the drilling and the ore layer. After the slitting is completed, the casing and the cement layer can keep the ore layer stable and prevent it from collapsing. The entire slitting operation only takes 3.0 to 3.5 h, greatly improving the construction efficiency compared with the existing mechanical cutting process which takes 12 to 14 h. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic structural diagram of the spaced slits in the casing, where 1-1 is the first spaced slit, 1-2 is the second spaced slit, and 1-3 is the third spaced slit;

[0019] Figure 2 It is the current logging curve of Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention provides a well completion method for in-situ leaching drilling, including the following steps:

[0021] The method is implemented by using a high-pressure water jet sandblasting device. The high-pressure water jet sandblasting device includes a high-pressure water jet spray gun, a sand mixing skid, and a pressure boosting skid. The method includes the following steps:

[0022] After cementing, lower the high-pressure water jet gun into the casing for interval cutting to obtain interval slits.

[0023] Lower an internal filter into the casing. The bottom of the filter is flush with the lowermost end of the interval slits, and the top of the filter is flush with the uppermost end of the interval slits.

[0024] The present invention implements the method using a high-pressure water jet sandblasting device. The high-pressure water jet sandblasting device includes a high-pressure water jet gun, a sand mixing skid, and a booster skid. Preferably, in the present invention, the sand mixing skid and the booster skid are connected by a stainless steel steel pipe and then connected to the high-pressure water jet gun. In the present invention, the sand mixing skid is used to mix cutting abrasives; the booster skid is used to provide the pressure required by the high-pressure water jet gun. In the present invention, the length of the high-pressure water jet gun is preferably 600 - 640 mm, more preferably 600 - 620 mm; the diameter of the high-pressure water jet gun is preferably 110 - 120 mm, more preferably 115 mm. In the present invention, the high-pressure water jet gun includes nozzles provided at the top and located in the same plane. The number of nozzles is preferably 1 - 4, more preferably 2 - 3. In the present invention, the diameter of the nozzles is preferably 2.5 - 4.5 mm, more preferably 3 - 4 mm. In the present invention, the product of the angle between adjacent two nozzles and the number of nozzles is 360°. In the present invention, when the number of nozzles is 2, the angle between adjacent two nozzles is 180 degrees; when the number of nozzles is 3, the angle between adjacent two nozzles is 120 degrees; when the number of nozzles is 4, the angle between adjacent two nozzles is 90 degrees.

[0025] After cementing, in the present invention, lower the high-pressure water jet gun into the casing for interval cutting to obtain interval slits. In the present invention, the cementing preferably includes the following steps: lower the casing into the open hole, and inject cement slurry reversely through the grouting holes reserved at the bottom of the casing. In the present invention, the open hole is preferably obtained by opening a hole with a drill bit. In the present invention, the diameter of the open hole is the same as the diameter of the drill bit. The diameter of the open hole is preferably 210 - 220 mm, more preferably 215 mm; the depth of the open hole is preferably 334 - 429 m, more preferably 420 - 427 m. In the present invention, the grouting holes are preferably located 0.1 m above the bottom of the casing; the shape of the grouting holes is preferably rectangular, circular or triangular, more preferably circular. In the present invention, the area of the grouting holes is preferably 300 - 900 cm 2 ², more preferably 350 - 480 cm 2 ²; in the present invention, the number of grouting holes is preferably 1 - 2. The present invention has no special requirements for the cement slurry, and conventional cement slurry in the art can be used.

[0026] In the present invention, the pressure of the high-pressure water jet gun during the spaced cutting is preferably 32 - 40 MPa, more preferably 35 - 36 MPa; the flow rate of the high-pressure water jet gun is preferably 260 - 450 L / min, more preferably 280 - 380 L / min.

[0027] In the present invention, the width of any single cut in the spaced slits is preferably 5 - 9 mm, more preferably 6 - 8 mm; the distance between any two single cuts in the spaced slits is preferably 90 - 110 mm, more preferably 100 mm. In the present invention, the number of the spaced slits is preferably 1 - 4, more preferably 2 - 3. In the present invention, the number of the spaced slits is preferably the same as the number of nozzles provided at the top end of the high-pressure water jet gun.

[0028] In the present invention, taking the number of the spaced slits being 3 as an example, the schematic structural diagram of the spaced slits in the casing is as Figure 1 shown, where 1 - 1 is the first spaced slit, 1 - 2 is the second spaced slit, and 1 - 3 is the third spaced slit. The three spaced slits are evenly distributed in the cross-section of the casing, and the width of the spaced slit is the slit width on the surface of the casing.

[0029] In the present invention, the total length of the spaced slits is preferably 5 - 11 m, more preferably 6 - 10 m.

[0030] In the present invention, the casing is not completely cut through by the spaced cutting, thereby avoiding permanent damage to the casing and ensuring the integrity of the casing.

[0031] After the spaced cutting is completed, an internal filter is lowered into the casing in the present invention. Before lowering the filter, it is preferably to perform an electric current logging to determine the actual position of the cut.

[0032] In the present invention, the filter preferably includes an annular outer frame filter, a gravel-packed filter or a slotted filter, more preferably a slotted filter. In the present invention, the bottom of the filter is flush with the lowermost end of the spaced slit, and the top of the filter is flush with the uppermost end of the spaced slit.

[0033] In the present invention, the lowering depth of the filter is preferably 321.0 - 423.5 m. The lowering depth of the filter in the present invention is preferably the same as the depth of the uranium ore layer. The present invention preferably uses the method of geophysical logging to detect the depth of the uranium ore layer.

[0034] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below in conjunction with embodiments, but they cannot be understood as limiting the protection scope of the present invention.

[0035] Example 1

[0036] Taking the production well drilling of uranium deposit SC0117 as an example for well completion:

[0037] Step 1: Use a Φ215mm bit to drill a bare hole with a diameter of 215mm and a depth of 429.0m. Lower a casing into the bare hole. Reserve a circular grouting hole with a diameter of 22cm at 0.1m (i.e., 428.9m) from the bottom of the casing. The area of the grouting hole is 380cm 2 , and use reverse cement slurry injection to complete well cementing;

[0038] Step 2: Use geophysical logging methods to detect that the depth of the uranium ore layer is 413.0 - 420.4m, and design the borehole slotted position to be 413.0 - 420.4m. Lower a high-pressure hydraulic jet gun from inside the casing to a depth of 420.4m. The length of the high-pressure hydraulic jet gun is 620mm, the diameter is 115mm, and 3 nozzles are set at the top. The included angle between two adjacent nozzles is 120°. Connect the high-pressure hydraulic jet gun with the surface sand mixing skid and the booster skid;

[0039] Step 3: Start the high-pressure hydraulic sandblasting device, and jet cutting abrasive from the nozzles to cut slots on the casing and the well cementing layer, cutting through the casing, the well cementing layer, and the nearby ore layer. The pressure of the high-pressure hydraulic jet gun is 36.0MPa, and the flow rate is 380.0L / min;

[0040] Step 4: During the slot cutting process, the high-pressure hydraulic sandblasting device moves from bottom to top for intermittent cutting. Cut every 800mm with a 100mm interval and then cut again. Stop the cutting construction until the depth of 413.0m is reached, and 3 spaced slots are obtained. The total length of each spaced slot is 7.4m;

[0041] Step 5: Use current logging to determine the actual slot cutting position to be 413.0 - 420.4m, and lower the slotted filter to a depth of 413.0 - 420.4m to complete the well completion process. The current logging curve is as Figure 2 shown.

[0042] The specific slot cutting positions of each spaced slot in Example 1 are shown in Table 1.

[0043] Table 1 Specific slot cutting positions of each spaced slot in Example 1

[0044]

[0045]

[0046] Example 2

[0047] Taking the production well drilling of uranium deposit SC0105 as an example for well completion:

[0048] Step 1: Use a Φ215mm drill bit to drill a bare hole with a diameter of 215mm and a depth of 427.0m, and lower a casing into the bare hole. A rectangular grouting hole is reserved at 0.1m from the bottom of the casing (i.e., 426.9m). Reverse cement grouting is used to complete well cementing. The grouting hole is rectangular, with a length of 30cm and a width of 12cm, and the area of the grouting hole is 360cm 2 ;

[0049] Step 2: Use geophysical logging to detect that the depth of the uranium ore layer is 413.0 - 423.5m, and design the slotting position to be 413.0 - 423.5m; Lower a high-pressure hydraulic jetting gun from inside the casing to a depth of 423.5m; The length of the high-pressure hydraulic jetting gun is 620mm, the diameter is 115mm, and 2 nozzles are set at the top, and the included angle between two adjacent nozzles is 180°; The high-pressure hydraulic jetting gun is connected to the surface sand mixing skid and booster skid;

[0050] Step 3: Turn on the high-pressure hydraulic sandblasting device, and jet cutting abrasives from the nozzles to cut slots on the casing and the well cementing layer, cutting through the casing, the well cementing layer and the nearby ore layer; The pressure of the high-pressure hydraulic jetting gun is 35.0MPa, and the flow rate is 320.0L / min;

[0051] Step 4: During the slotting process, the high-pressure hydraulic sandblasting device moves from bottom to top for intermittent cutting. When cutting every 900mm, there is an interval of 100mm and then cutting again; Until the cutting reaches a depth of 413.0m, stop the cutting construction to obtain 2 intermittent slots, and the total length of each intermittent slot is 10.5m;

[0052] Step 5: Use electric logging to determine the actual slotting position to be 413.0 - 423.5m, and lower the slotted filter to a depth of 413.0 - 423.5m to complete the well completion process.

[0053] Example 3

[0054] Take the production well drilling of uranium deposit SC3557 as an example for well completion:

[0055] Step 1: Use a Φ215mm drill bit to drill a bare hole with a diameter of 215mm and a depth of 334.0m, and lower a casing into the bare hole. A triangular grouting hole is reserved at 0.1m from the bottom of the casing (i.e., 333.9m). Reverse cement grouting is used to complete well cementing. The triangle is an equilateral triangle, the side length of the triangle is 30cm, and the area of the grouting hole is 389.7cm 2 ;

[0056] Step 2: Use geophysical logging method to detect that the depth of the uranium ore layer is 321.0 - 329.5 m, and design the drilling slotting position to be 321.0 - 329.5 m; Lower the high-pressure hydraulic jet gun from inside the casing to a depth of 329.5 m; The length of the high-pressure hydraulic jet gun is 620 mm, the diameter is 115 mm, and 3 nozzles are set at the top, and the included angle between two adjacent nozzles is 120°; The high-pressure hydraulic jet gun is connected to the surface sand mixing skid and the booster skid;

[0057] Step 3: Turn on the high-pressure hydraulic sandblasting device, spray cutting abrasive from the nozzles to cut slots on the casing and the cement sheath, and cut through the casing, the cement sheath and the nearby ore layer; The pressure of the high-pressure hydraulic jet gun is 32.0 MPa, and the flow rate is 280.0 L / min;

[0058] Step 4: During the slotting process, the high-pressure hydraulic sandblasting device moves from bottom to top for intermittent cutting. When cutting every 900 mm, there is an interval of 100 mm and then cutting again; Until the cutting reaches a depth of 321.0 m, stop the cutting construction to obtain 3 intermittent slots, and the total length of each intermittent slot is 8.5 m;

[0059] Step 5: Use electric logging to determine the actual slotting position to be 321.0.0 - 329.5 m, and lower the gravel-packed filter with a porosity of 24% to a depth of 321.0 - 329.5 m to complete the well completion process.

[0060] Comparative Example 1

[0061] Take the mechanical cutting well completion method as the comparative example;

[0062] Construct an in-situ leaching uranium drilling hole, the opening diameter of the drilling hole is 269 mm, one diameter to the bottom, the casing is 152×12 mm, and the filter is an annular outer frame filter; Use mechanical cutting method to build the filter section, and then install the built-in filter;

[0063] Construction process: hole opening → diameter reduction → logging → hole enlargement → punching → pipe lowering → reverse injection of cement slurry → lowering the cutting tool to cut the casing → lowering the hole enlargement tool to enlarge the hole → punching → lowering the built-in filter assembly;

[0064] The ore layer position is 343.05 - 350.65 m, and the length is 7.6 m; Lower the cutting tool to cut the casing, the cutting length is 7.6 m, and the cutting time is 8.5 hours; By the method of right-angled triangular weir, the acceptance water volume of the drilling hole is detected to be 10.20 m 3 / h.

[0065] Detect the acceptance water volume according to the method of right-angled triangular weir, and the results are listed in Table 2.

[0066] Table 2 Well completion time and acceptance water volume of Examples 1 - 3 and Comparative Example 1

[0067]

[0068]

[0069] It can be seen from Examples 1 to 3 and Comparative Example 1 that the slotting efficiency in the examples is high, the slotting time is short, and the time consumption is 3.2 to 4.0 h. However, the cutting time of Comparative Example 1 is 8.5 h, and the method adopted in the examples is superior to that of the comparative example. The acceptance water volume of the slotting and drilling in the examples is all above 11.66 m 3 / h, which is superior to the comparative example. In Example 1 and Comparative Example 1, the lengths of the drilled ore layer and the filter are close, being 7.4 m and 7.6 m respectively. The slotting and drilling are superior to Comparative Example 1 both in construction time and acceptance water volume, indicating the superiority of the slotting and drilling process.

[0070] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all the embodiments. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A well completion method for in-situ leaching drilling, which implements the method by using a high-pressure hydraulic sandblasting device. The high-pressure hydraulic sandblasting device includes a high-pressure hydraulic jet spray gun, a sand mixing skid, and a booster skid. The method includes the following steps: After cementing, lower the high-pressure hydraulic jet spray gun into the casing for interval cutting to obtain interval slits. The width of any single slit in the interval slits is 5 - 9 mm; the distance between any two single slits in the interval slits is 90 - 110 mm; the total length of the interval slits is 5 - 11 m; Lower an internal filter into the casing. The bottom of the filter is flush with the lowermost end of the interval slits, and the top of the filter is flush with the uppermost end of the interval slits.

2. The well completion method of the in-situ leaching drilling well according to claim 1, characterized in that, The pressure of the high-pressure hydraulic jet spray gun is 32 - 40 MPa, and the flow rate of the high-pressure hydraulic jet spray gun is 260 - 450 L / min.

3. The well completion method of the in-situ leaching drilling well according to claim 2, characterized in that, The length of the high-pressure hydraulic jet spray gun is 600 - 640 mm, and the diameter of the high-pressure hydraulic jet spray gun is 110 - 120 mm.

4. The well completion method of the immersion drilling well according to claim 2 or 3, characterized in that, The high-pressure hydraulic jet spray gun includes nozzles arranged at the top and located in the same plane. The number of the nozzles is 1 - 4; The diameter of the nozzles is 2.5 - 4.5 mm; the product of the angle between two adjacent nozzles and the number of nozzles is 360°.

5. The well completion method of the in-situ leaching drilling well according to claim 1, characterized in that, The cementing includes the following steps: lower a casing into the open hole, and inject cement slurry reversely through the grouting holes reserved at the bottom of the casing.

6. The well completion method of the in-situ leaching drilling well according to claim 5, characterized in that, The diameter of the open hole is 210 - 220 mm, and the depth of the open hole is 334 - 429 m.

7. The well completion method of the immersion drilling well according to claim 1 or 6, characterized in that, The lowering depth of the filter is 321.0 - 423.5 m.

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