A deep mineral drilling exploration method

Abstract

The present invention relates to a deep mineral drilling exploration method, which belongs to the field of geological survey and mineral exploration, and comprises the following steps: core drilling, drilling out a borehole; when a certain deep mineral layer is encountered, core drilling into the deep mineral layer to determine the impact tendency of the deep mineral layer; if the deep mineral layer has an impact tendency, hydraulic fracturing and pressure relief are performed on it to form a horizontal fracturing fissure; acid is injected to expand the width of the horizontal fracturing fissure; drilling down to a certain depth, and using mud to protect the wall of the deep mineral layer bare hole; lowering a flying pipe; pouring cement slurry into the borehole, fixing the flying pipe in the borehole; using a conventional drill bit to drill to the depth of the original step e drilling; replacing the core drill bit, and continuing drilling. The present invention can solve the problem of deep mineral layers creeping into the borehole and improve the accuracy of drilling exploration.

Description

Technical Field

[0001] The invention belongs to the field of geological survey and mineral exploration, and specifically relates to a deep mineral drilling exploration method. Background Art

[0002] Mineral exploration is a practical geology that studies the geological conditions of mineral formation and distribution, the occurrence law of ore deposits, the characteristics of ore body changes, and the most effective identification and evaluation methods. The task of mineral exploration is to discover and identify industrial ore deposits. To this end, geological mapping, geophysical exploration, geochemical exploration, drilling, pit exploration and other prospecting methods must be used, and sampling and analysis must be carried out. The most commonly used in the existing technology is the drilling and coring prospecting process, but for deep ore layers, especially those with a burial depth of more than 800m, affected by the stratum pressure and the hardness of the ore layer is less than the rock layer, after the borehole is drilled through the ore layer, the ore layer will creep / mutate and unload pressure into the borehole. The ore blocks of the ore layer will fall into the borehole, affecting subsequent drilling exploration, and then affecting subsequent exploration and analysis. This phenomenon is more obvious during drilling exploration in coal mines, because the hardness of coal is much smaller than that of the surrounding rock layers, and the deep buried coal seams in coal mines usually have impact tendency. Summary of the invention

[0003] In order to solve the technical problem that the creep of the ore layer in the borehole affects the subsequent drilling exploration during deep mineral exploration, the present invention proposes a deep mineral drilling exploration method, comprising the following steps:

[0004] a. Core drilling and drilling out of the borehole;

[0005] b. When a deep ore layer is encountered, core drilling is carried out into the deep ore layer to determine the impact tendency of the deep ore layer;

[0006] c. If the deep ore layer has impact tendency, hydraulic fracturing is performed to relieve pressure and form horizontal fracturing fissures;

[0007] d. Inject acid into the horizontal fracturing cracks to expand the crack width;

[0008] e. Continue to drill down to a certain depth;

[0009] f. lowering the flying pipe, the outer diameter of which is slightly smaller than the borehole diameter, and the length of which is greater than the thickness of the deep ore layer;

[0010] g. Pour cement slurry into the borehole to fix the flying pipe in the borehole;

[0011] h. Drill to the original drilling depth of step e using a conventional drill bit;

[0012] i. Replace the core drill bit and continue drilling;

[0013] j. When encountering a deep ore layer again, repeat step bi until drilling reaches the designed depth.

[0014] Preferably, in step a, the drilled hole is a bare hole.

[0015] Preferably, in step b, the on-site drilling conditions are comprehensively considered, and samples are made from the removed cores for testing to determine the impact tendency of the deep ore layer.

[0016] Preferably, in step d, the acid solution is a mixed acid solution with a mass fraction of 15%-20% hydrochloric acid, 2%-4% hydrofluoric acid, and 1%-2% acetic acid.

[0017] Preferably, in step f, the length of the flying pipe can cover the entire thickness of the deep ore layer.

[0018] Preferably, in step g, the flying tube is centered, and then cement slurry is poured into the borehole until the cement slurry covers the upper end of the flying tube to a certain height; the cement slurry is left to stand for a period of time to solidify and form a cement layer; the cement layer includes the gap between the flying tube and the bare hole, and also includes the cement layer located within the inner diameter of the flying tube.

[0019] Preferably, in step h, a cement layer in the gap between the fly-removing pipe and the open hole is drilled.

[0020] Preferably, in step i, a special drill pipe is used, the special drill pipe includes a centralizer located in the middle and evenly distributed in the circumference, and a locking tongue is arranged in the middle of the centralizer, and the sharp part of the locking tongue faces downward. Further, the outer diameter of the locking tongue when retracted is not greater than the inner diameter of the flying tube, and the outer diameter when extended is not less than the inner diameter of the flying tube. Furthermore, the outer diameter when extended is equal to the outer diameter of the flying tube.

[0021] The beneficial technical effects of the present invention are as follows: 1. In view of the problem of creep toward the borehole caused by impact-prone mineral layers during core drilling and exploration of deep mineral layers, the present invention proposes first to use hydraulic fracturing to form horizontal cracks to relieve the pressure of the deep mineral layers, and then to expand the horizontal cracks through acidification to provide sufficient deformation space for subsequent creep of the deep mineral layers, and then to use casing to protect the deep mineral layers to prevent the deep mineral layers from creeping into the borehole.

[0022] 2. In order to prevent the casing from falling and being difficult to remove, resulting in the scrapping of the drilling, the present invention specially manufactures a drill rod, which includes a centralizer located in the middle and evenly distributed circumferentially. A locking tongue is arranged in the middle of the centralizer, and the sharp part of the locking tongue faces downward.

[0023] 3. The present invention can solve the problem of deep ore layers creeping into the borehole and improve the accuracy of drilling exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1Schematic diagram of the drilling process when the deep mineral exploration drilling encounters a coal layer (only the drilling part near the coal layer is taken in the up and down directions);

[0025] Figure 2 The drill rod for deep mineral drilling exploration of the present invention;

[0026] In the figure, borehole 1, coal mine layer 2, fracturing fissure 3, cement 4, casing (flying pipe) 5, drill pipe 6, centralizer 7, locking tongue 8. DETAILED DESCRIPTION

[0027] Take the deep drilling survey of coal mine seams as an example;

[0028] like Figure 1-2 As shown, a deep mineral drilling exploration method is used for coal mine layer drilling exploration, comprising the following steps:

[0029] a. Coring drilling, drilling a borehole 1 in the coal rock layer section, wherein the borehole 1 is an open hole;

[0030] b. When drilling to a depth of 867.1m, a coal layer 2 is encountered, where 867.1m is the buried depth of the top interface of the coal layer. The core is drilled into the coal layer 2 and the thickness of the coal layer is 4.3m, that is, the buried depth of the bottom interface of the coal layer is 871.4m. Based on the on-site drilling situation and the test of the coal samples taken out, it is determined that the coal layer has an impact tendency;

[0031] c. Raise the drill pipe, perform hydraulic fracturing to decompress the coal layer 2, and generate horizontal fracturing fissures 3 in the coal layer 2;

[0032] d. Injecting acid into the horizontal fracturing fissure 3 to expand the fissure width; the acid can be a mixed acid of hydrochloric acid, hydrofluoric acid, and acetic acid with mass fractions of 15%-20%, 2%-4%, and 1%-2%, respectively;

[0033] e. Continue to drill down to the bottom interface of the sandstone layer at the bottom of the coal mine layer, and drill to a depth of 874.6m. This step drills a total of 3.2m, that is, the thickness of the sandstone layer is 3.2m;

[0034] f. The casing (flying pipe) 5 is lowered, the outer diameter of the casing 5 is slightly smaller than the open hole diameter of the borehole 1, the length of the casing is greater than the thickness of the coal layer, and the embodiment selected is 9.8m;

[0035] g. Center the casing (flying pipe) 5, and then pour cement slurry into the borehole 1 until the cement slurry covers a certain height above the upper end of the casing (flying pipe) 5; let it stand for a period of time until the cement slurry solidifies and forms a cement layer; the cement layer includes the gap between the casing (flying pipe) 5 and the open hole, which can fix the casing (flying pipe) 5 in the borehole, and also includes a cement layer located within the inner diameter of the casing (flying pipe) 5, which needs to be drilled out later;

[0036] h. Use a conventional drill bit (without coring) to drill into the cement layer except the gap between the casing (flying pipe) 5 and the open hole until the bottom interface of the sandstone layer in step e, that is, drill to 874.6m;

[0037] i. Replace the core drill bit and use a special drill rod 6 for subsequent drilling. The special drill rod 6 includes a centralizer 7 located in the middle and evenly distributed around the circumference. A locking tongue 8 is arranged in the middle of the centralizer. The sharp part of the locking tongue 8 faces downward, that is, it is wide at the top and narrow at the bottom, and it can be extended and retracted in the horizontal direction. The outer diameter of the locking tongue when retracted is not larger than the inner diameter of the casing (flying tube) 5, and the outer diameter when extended is not smaller than the inner diameter of the casing (flying tube) 5, preferably equal to the outer diameter of the casing (flying tube) 5; preferably, the locking tongue can be connected to the drill rod through a spring. j. When the coal mine layer is encountered again, repeat step bi until the drilling reaches the designed depth.

Claims

1. A deep mineral drilling exploration method, It is characterized in that The steps include: a. Core drilling and drilling out of the borehole; b. When a deep ore layer is encountered, core drilling is carried out into the deep ore layer to determine the impact tendency of the deep ore layer; c. If the deep ore layer has impact tendency, hydraulic fracturing is performed to relieve pressure and form horizontal fracturing fissures; d. Inject acid into the horizontal fracturing cracks to expand the crack width; e. Drill down to a certain depth after coring; f. The flying pipe is lowered, the outer diameter of the flying pipe is slightly smaller than the borehole diameter, the length is greater than the thickness of the deep ore layer and the flying pipe covers the entire thickness of the deep ore layer; g. Pour cement slurry into the borehole to fix the flying tube in the borehole until the cement slurry is submerged to a certain height above the upper end of the flying tube, and the cement layer formed includes the gap between the flying tube and the bare hole, and also includes a cement layer located within the inner diameter of the flying tube; h. Drill to the original drilling depth of step e using a conventional drill bit, drilling into the cement layer in addition to the gap between the flying pipe and the open hole; i. Replace the core drill bit and continue drilling; j. When encountering a deep ore layer again, repeat step bi until drilling reaches the designed depth.

2. The deep mineral drilling exploration method according to claim 1, It is characterized in that In step a, the drilled hole is a bare hole.

3. The deep mineral drilling exploration method according to claim 1, It is characterized in that In step b, the on-site drilling situation is comprehensively considered, and samples are made from the extracted cores for testing to determine the impact tendency of the deep ore layer.

4. The deep mineral drilling exploration method according to claim 1, It is characterized in that In step d, the acid solution is a mixed acid solution with a mass fraction of 15%-20% hydrochloric acid, 2%-4% hydrofluoric acid, and 1%-2% acetic acid.

5. The deep mineral drilling exploration method according to claim 1, It is characterized in that In step g, the flying pipe is centered, and then cement slurry is poured into the borehole; after pouring, the cement slurry is left to stand for a period of time to solidify and form a cement layer.

6. The deep mineral drilling exploration method according to claim 5, It is characterized in that In step i, a special drill rod is used, and the special drill rod includes a centralizer located in the middle thereof. A locking tongue is arranged in the middle of the centralizer, and the sharp part of the locking tongue faces downward.

7. The deep mineral drilling exploration method according to claim 6, It is characterized in that The outer diameter of the lock tongue when retracted is not larger than the inner diameter of the flying tube, and the outer diameter of the lock tongue when extended is not smaller than the inner diameter of the flying tube.

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