Solid ore body range delineation method and natural gamma measurement while drilling instrument for direction difference

Abstract

The invention provides a solid ore body range delineation method for radioactive distinguishing and a natural gamma measurement-while-drilling instrument for direction difference. The solid ore body range delineation method for radioactive distinguishing comprises the following steps: surrounding a sodium iodide crystal by using a radioactive shielding material on the periphery of the sodium iodide crystal on a gamma detector of a natural gamma measurement-while-drilling instrument to form an annular radiation shielding cover, and leaving a window capable of emitting a radiation signal on the annular radiation shielding cover, therefore, the natural gamma measurement-while-drilling instrument shows difference when detecting the radioactivity of the surrounding environment in the rotating process. A direction difference natural gamma measurement while drilling instrument comprises a scintillator and a radiation shielding cover, the radiation shielding cover is made of radioactive shielding materials, and the annular radiation shielding cover is provided with a window capable of emitting radiation signals. According to the method, the range of the ore body can be accurately delineated.

Description

Technical Field

[0001] The invention relates to the field of solid ore body exploration, and in particular to a solid ore body range delineation method for radioactivity differentiation and a natural gamma-ray while-drilling measuring instrument for directional difference. Background Art

[0002] Solid minerals are formed by volcanic activity or sedimentation, and exist in irregular shapes such as veins, blocks, and sheets. After a long geological era, most of them are now deeply buried underground. Due to later tectonic actions, the shapes and occurrences of these deposits have been highly distorted by structures such as faults and folds compared to their original states, and more detailed exploration work is needed to roughly define their scope.

[0003] The exploration process of solid minerals is to go through geological survey, detailed survey and then fine survey, delineate the scope of the ore body, and then calculate the reserves and submit them to the government department in charge. After the approval of the government department in charge, development can be carried out. To delineate the scope of the ore body, it is necessary to drill geological exploration holes, obtain core data, determine the top and bottom boundaries of the ore body at a certain point, and then drill multiple holes within a certain range to obtain the top and bottom boundaries of the ore body at multiple points. By connecting these points, the approximate scope of the ore body can be obtained. The accuracy of the ore body scope depends on the density of the drill holes. Due to insufficient density, some small faults and folds cannot be reflected in the exploration results, so they will be lost in the mining stage, and further work and cost are required to find out.

[0004] In summary, the prior art has the following problems: During the mining stage, the prior art cannot accurately determine the ore body for high-precision on-site delineation, or in other words, cannot determine the precise range of the solid ore body. Summary of the invention

[0005] The present invention provides a method for delineating the scope of a solid mineral body, for example: a method for accurately delineating the scope of a solid mineral body for radioactive differentiation, and a natural gamma-ray while-drilling measurement instrument for directional difference, so as to solve the problem of high-precision on-site delineation of mineral bodies that cannot be accurately determined by existing technical means.

[0006] To this end, the present invention proposes a method for delineating the scope of a solid mineral body for radioactive differentiation, and the method for delineating the scope of a solid mineral body for radioactive differentiation comprises:

[0007] In the underground drilling exploration of solid mines, natural gamma-ray measurement while drilling instruments are used for data collection;

[0008] Among them, radioactive shielding material is used to surround the sodium iodide crystal on the gamma detector of the natural gamma ray while drilling instrument to form an annular radiation shielding cover, and then a window that can emit radiation signals is left on the annular radiation shielding cover, so that the natural gamma ray while drilling instrument will show differences when detecting the radioactivity of the surrounding environment during the rotation process.

[0009] Furthermore, the window is a 10-70° sector.

[0010] Furthermore, the window is a 20-60° sector.

[0011] Furthermore, the method further includes: calculating the gamma values ​​within a unit time in a sector range of 20-60° just above and just below the probe of the natural gamma measurement while drilling instrument.

[0012] Furthermore, the method further includes: when the probe of the natural gamma ray while drilling instrument rotates through the radioactive formation interface, the gamma values ​​above and below the probe of the natural gamma ray while drilling instrument appear to be discrete with respect to the mean value.

[0013] Furthermore, the discrete phenomenon is specifically: when the radioactivity value of the formation above the probe is greater than that below, the upper gamma value is high, and when the radioactivity value of the formation below the probe is greater than that above, the lower gamma value is high.

[0014] The present invention also provides a directional difference natural gamma measurement while drilling instrument, comprising: a scintillator, and an annular radiation shielding cover surrounding the scintillator, wherein the radiation shielding cover is made of radioactive shielding material, wherein the annular radiation shielding cover is provided with a window capable of emitting a radiation signal.

[0015] Furthermore, the scintillator is sodium iodide crystal.

[0016] Furthermore, the window is a 10-70° sector.

[0017] Furthermore, the window is a 20-60° sector.

[0018] The method of the present invention is applied in the mining stage to carry out high-precision on-site delineation of ore bodies that cannot be accurately determined by existing technical means. Principle of the invention: Radioactive solid ore refers to a mineral deposit in which the ore body itself contains significantly more radioactive elements such as thorium, uranium, radium, potassium, etc. than the surrounding rock, such as uranium ore, phosphate ore, fluorite ore, rare earth ore, etc. Due to this characteristic, these mines can be identified and distinguished using natural gamma instruments during the exploration stage, for example, the natural gamma response of phosphate ore. In addition, there are some solid ore bodies, such as coal, which contain relatively few radioactive elements themselves, but when the sandstone and mudstone of the surrounding rock, especially the mudstone, have a relatively high content, they can also be identified using natural gamma instruments (natural gamma logging instruments). For example, the natural gamma response of coal seams.

[0019] The present invention uses a radioactive shielding material (such as lead) to surround the scintillator, or scintillator crystal or crystal, such as sodium iodide (NAI) crystal, on a gamma detector (natural gamma logging instrument) (crystal length 30-150 mm, thickness 25-50 mm), and then leaves a window on the radiation shielding cover (for example, a 60-degree fan-shaped area, the axial length of the fan-shaped area is less than or equal to the length of the scintillator 17), so that the natural gamma logging instrument presents differences when detecting the radioactivity of the surrounding environment during rotation.

[0020] The gamma values ​​in the sectors directly above and below the probe within a unit time are counted (the probe needs to open a window because there is a difference between the data collected by the window of the formation interface and the data collected by the non-window. (For example, through an algorithm), this difference is screened out and matched with the tool surface parameters indicated by the MWD measurement while drilling instrument to know the difference between the upper and lower formations. That is, the parameter matching method of the upper and lower tool surfaces of the MWD measurement while drilling instrument in the oil and gas industry can be adopted or referred to). When the probe rotates through the radioactive formation interface, the gamma values ​​above and below the probe will be discrete relative to the mean (that is, the two curves of the gamma values ​​above and below the probe are not intertwined, which is discrete). When the formation radioactivity value above the probe is significantly greater than that below (based on the measured curves not intertwining), the upper gamma value is high. When the formation radioactivity value below the probe is significantly greater than that above, the lower gamma value is high. In this way, the scope of the ore body can be more accurately delineated. The scope of the ore body can be accurate to within 1 meter, or even within 0.1 meter. For example, if the thickness of the ore body is about 10 meters, the error can be controlled within 0-1 meter, and the error source is mainly the distance between the marker layer and the upper and lower interfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram of gamma value data changes of a natural gamma measurement while drilling instrument using the present invention; Figure 1 The vertical axis is the gamma depth, the unit is meter; the horizontal axis is the gamma value, the unit is API;

[0022] Figure 2 It is a structural schematic diagram of the main viewing direction of the natural gamma-ray while drilling measurement instrument with directional difference of the present invention;

[0023] Figure 3 It is a schematic structural diagram of the radiation shielding cover and the scintillator of the natural gamma ray while drilling instrument with directional difference of the present invention;

[0024] Figure 4 A schematic diagram of the detection principle of using the natural gamma-ray measurement while drilling instrument of the present invention to detect differences in the radioactivity of the surrounding environment;

[0025] Figure 5 It is a schematic diagram of the principle of delineating the scope of the ore body in the prior art;

[0026] Figure 6 It is a schematic diagram of the principle of delineating the scope of the ore body using the present invention;

[0027] Figure 7 A schematic diagram of the principle of delineating the scope of the ore body using the present invention when long drilling is required and there is a marker layer;

[0028] Figure 8 A schematic diagram of the principle of delineating the scope of the ore body by using the present invention when a long drill is required and a marker layer is present and a fault is encountered;

[0029] Fig. 9 A schematic diagram of the principle of delineating the scope of the ore body using the present invention when long drilling is required and there is no marker layer;

[0030] Fig.10 A schematic diagram of the principle of delineating the scope of an ore body using the present invention under the requirement of short drilling.

[0031] Description of Figure Numbers:

[0032] 1. Probe; 11. Connector; 12. High voltage and circuit processing device; 13. Photomultiplier tube; 15. Radiation shielding cover; 16. Packaging cover; 17. Scintillator; 160. Window; 18. Probe housing. DETAILED DESCRIPTION

[0033] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the present invention is now described with reference to the accompanying drawings.

[0034] The present invention provides a method for delineating the scope of a solid mineral body for radioactive differentiation, and the method for delineating the scope of a solid mineral body for radioactive differentiation comprises:

[0035] In the underground drilling exploration of solid mines, natural gamma-ray measurement while drilling instruments are used for data collection;

[0036] Among them, Figure 2 , Figure 3 and Figure 4 As shown, a radioactive shielding material is used to surround the sodium iodide crystal on the periphery of the scintillator 11 (for example, sodium iodide crystal) of the gamma detector of the natural gamma ray while drilling instrument to form an annular radiation shielding cover 15, and then a window 160 that can emit a radiation signal is left on the annular radiation shielding cover, so that the natural gamma ray while drilling instrument presents differences when detecting the radioactivity of the surrounding environment during the rotation process.

[0037] The gamma values ​​in the sector directly above and below the probe of the natural gamma MWD instrument are counted per unit time. Figure 1As shown in the figure, when the probe of the natural gamma while drilling instrument rotates through the radioactive formation interface, the gamma values ​​above and below the probe of the natural gamma while drilling instrument appear discrete with respect to the mean. When the formation radioactivity value above the probe is greater than that below, the upper gamma value (i.e., the gamma value above the probe) is high; when the formation radioactivity value below the probe is greater than that above, the lower gamma value (i.e., the gamma value below the probe) is high, as shown in the figure. Figure 1 shown.

[0038] Furthermore, the windowing is a 40-70° sector, so that both the signal can be sent and the difference between the upper and lower gamma values ​​can be achieved.

[0039] Furthermore, the window is a 60° sector, and this angle can effectively reflect the discrete phenomenon of the gamma values ​​above and below the probe relative to the mean.

[0040] The present invention also provides a natural gamma ray while drilling measuring instrument with directional difference, such as Figure 2 and Figure 3 As shown, the directional difference natural gamma measurement while drilling instrument comprises: a probe 1, which mainly comprises: a photomultiplier tube 13, a scintillator 17, an annular radiation shielding cover 15 surrounding the scintillator, and a measuring short section MWD; the photomultiplier tube 13, the scintillator 17 and the measuring short section MWD can all adopt the structure of existing probes;

[0041] like Figure 2 and Figure 3 As shown, the probe 1 specifically includes: a connector 11, a high voltage and circuit processing device 12, a photomultiplier tube 13, a scintillator 17, a radiation shielding cover 15, and a probe housing 18. Figure 3 As shown, the main features of the present invention are: a ring-shaped radiation shielding cover 15 is provided surrounding the periphery of the scintillator, and a window 160 is provided on the radiation shielding cover 15. Outside the window 160 is a probe housing 18, the radiation shielding cover is made of a radioactive shielding material, such as lead, the probe housing 18 only plays a protective role and does not hinder the reception of radiation signals, and the probe housing 18 is a non-radioactive shielding material, that is, it is made of an existing probe housing material.

[0042] in, Figure 3 FIG. 1 is a schematic diagram of the structure of the radiation shield and scintillator of the natural gamma ray while drilling instrument with directional difference of the present invention, that is, Figure 3The structure of the radiation shield 15 and the scintillator 17 is shown in the cross-sectional direction or radial direction of the probe of the natural gamma-ray drilling measurement instrument with directional differences. The annular radiation shield 15 is provided with a window 160 that can emit a radiation signal, that is, the annular radiation shield 15 has a window 160, such as a fan-shaped gap, which is not shielded by radiation, and a radiation signal can be emitted through the fan-shaped gap. The fan-shaped gap is a geological information collection window. The window 160 is, for example, a 60-degree fan-shaped area, also called an open sector. The axial length of the fan-shaped area is less than or equal to the length of the scintillator 17, for example, 20-140 mm. According to the effect of signal transmission, the axial length of the window 160 can be selected to be 10 mm, 40 mm, 60 mm, or 80 mm.

[0043] Furthermore, the scintillator is a sodium iodide crystal, and the sodium iodide crystal is doped with thallium as an activator, and has a good application effect.

[0044] like Figure 5 As shown, for example, a radioactive ore body is undulating in profile, and there is no difference between the upper and lower surrounding rocks. During the drilling process, the drill bit is easy to go out of the layer. The existing technology cannot determine whether the drill bit is above or below the target layer. In this case, the use of the azimuth (discrete) gamma instrument of the present invention, that is, the directional difference natural gamma measurement while drilling instrument, can clearly determine that the drill bit has entered the upper part of the target layer, where the stratum has undergone obvious changes. Figure 6 As shown, high and low gammas are separated, and high gammas indicate that the lower strata have higher radioactivity. For a specific solid ore, it is necessary to understand the specific requirements, including long drill requirements and short drill requirements.

[0045] 1. Long drilling requirements: For example, if it is known that there is an unknown ore body 200 meters ahead, and the mine requires the precise direction of the ore body within this 200-meter range to be obtained in advance, the following workflow can be adopted:

[0046] By collecting data or drilling test holes, the natural gamma characteristics of the ore body can be determined to see if there are any stratifications inside it, which can be used as a marker layer for geological guidance. The marker layer is ubiquitous and is produced in a specific geological history period. Its upper and lower distances from the target ore body are basically constant. If there is a marker layer, the natural gamma value of the marker layer is different from that of the surrounding rocks above and below it. Figure 7 As shown in the figure, first drill a hole in the target layer and control the drill bit to move up and down along the marker layer until the drilling is completed; Figure 8 As shown, if a large structural undulation is encountered, such as a fault, and the drill bit is out of the layer and too far away from the marker layer, the drill bit should be pulled back for side drilling.

[0047] Through such drilling, the upper and lower boundaries of the ore body can be calculated more accurately. If the thickness of the ore body is about 10 meters, the error can be controlled within 0-1 meter. The error mainly comes from the distance between the marker layer and the upper and lower interfaces.

[0048] If the target layer is relatively uniform inside and has no marker layer, such as Fig. 9 As shown in the figure, through the top-bottom drilling, the natural gamma-ray MWD instrument shows differences in detecting the radioactivity of the surrounding environment during the rotation process. The drilling and exploration method is adopted. Every time a certain distance is drilled, such as 20 meters, the top and bottom are intentionally touched to obtain accurate ore body thickness data. The accuracy of different top-bottom points can be as low as 0.1 meters. If the drill encounters a fault, after determining the drill bit position, it goes up or down into the fault rising plate or descending plate to continue drilling in the target layer.

[0049] Second, short drilling requirements: Usually the ore body is relatively hard and has an irregular shape. It needs to be detected in all directions. Cluster drilling is used to detect the range of the ore body. Fig.10 As shown, a hole is opened inside the ore body, and detection is conducted in four directions, up, down, left, and right, from four points A, B, C, and D located at the midpoint of the rectangle on the vertical plane. The detection ends at the boundary or the specified distance, for example, the end point is the four boundary points A1, B1, C1, and D1. The accuracy error of the ore body circled in this way is about 0.1 meters. (Because we know where we went out after the boundary, the gamma of the boundary is different from that of the ore body itself)

[0050] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. The components of the present invention can be combined with each other without conflict, and any equivalent changes and modifications made by any technician in the field without departing from the concept and principle of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for delineating the scope of a solid ore body for radioactivity differentiation, characterized in that: The solid ore body scoping method for radioactive differentiation includes: In the underground drilling exploration of solid mines, natural gamma-ray measurement while drilling instruments are used for data collection; Among them, radioactive shielding material is used to surround the crystal of the scintillator on the probe of the natural gamma ray while drilling meter to form an annular radiation shielding cover, and then a window that can emit a radiation signal is left on the annular radiation shielding cover, so that the natural gamma ray while drilling meter shows differences when detecting the radioactivity of the surrounding environment during the rotation process.

2. The method for delineating the scope of a solid ore body for radioactive differentiation according to claim 1, characterized in that: The window is a 40-70° sector.

3. The method for delineating the scope of a solid ore body for radioactive differentiation according to claim 1, characterized in that: The window is a 60° sector.

4. The method for delineating the scope of a solid ore body for radioactive differentiation according to claim 1, characterized in that: Also includes: The gamma values ​​within the 20-60° sector directly above and below the probe of the natural gamma measurement while drilling instrument are counted per unit time.

5. The method for delineating the scope of a solid ore body for radioactive differentiation according to claim 1, characterized in that: Also includes: When the probe of the natural gamma ray while drilling instrument rotates through the radioactive formation interface, the gamma values ​​above and below the probe of the natural gamma ray while drilling instrument appear to be discrete with respect to the mean value.

6. The method for delineating the scope of a solid ore body for radioactive differentiation according to claim 5, characterized in that: The discrete phenomenon is specifically: when the radioactivity value of the stratum above the probe is greater than that below, the upper gamma value is high; when the radioactivity value of the stratum below the probe is greater than that above, the lower gamma value is high.

7. A directional difference natural gamma-ray while drilling measurement instrument, characterized in that: include: A scintillator and an annular radiation shielding cover surrounding the scintillator, wherein the radiation shielding cover is made of radioactive shielding material, wherein the annular radiation shielding cover is provided with a window capable of emitting a radiation signal.

8. The directional difference natural gamma measurement while drilling instrument according to claim 7, characterized in that: The scintillator is sodium iodide crystal.

9. The directional difference natural gamma measurement while drilling instrument according to claim 7, characterized in that: The window is a 40-70° sector.

10. The directional difference natural gamma measurement while drilling instrument according to claim 7, characterized in that: The window is a 60° sector.

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