Method for exploring manganese ore based on well-well induced polarization technique

Abstract

The present application belongs to the technical field of manganese ore exploration, and particularly relates to a method for exploring manganese ore based on well-to-well induced polarization technology, comprising the following steps: step 1, arranging a current injection well and a potential measurement well in a target mining area; step 2, expanding a surrounding rock fissure network by using high-pressure hydraulic fracturing technology in a target well section; step 3, injecting brine into the fractured section; and step 4, sampling and analyzing induced polarization signals of the bottom layer between the wells. The present application expands the surrounding rock fissure network and improves the formation permeability by implementing high-pressure hydraulic fracturing in the target well section. Then, the brine is injected to enhance the current conduction path, improve the formation conductivity and the polarization ability of the ore body surface. The combination strengthens the response strength and spatial distribution uniformity of the induced polarization signals, lays a foundation for subsequent high-resolution detection, solves the problems of weak induced polarization anomaly and low signal-to-noise ratio of manganese ore, and has a good application prospect in the technical field of manganese ore exploration.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of manganese ore exploration, and particularly relates to a method for exploring manganese ore based on well-to-well induced polarization technology. BACKGROUND

[0002] Induced polarization (IP) is a widely used geophysical electrical method in mineral resource exploration. The basic principle is that when a low-frequency current is applied to the underground medium, the electrically active interfaces such as metal mineralization, electrolyte ion adsorption layer existing in the ore body or surrounding rock will produce "polarization phenomenon". When the current stops, these polarization effects will cause the secondary electric field to decay slowly, thus showing a characteristic induced polarization effect. By collecting the change curve of the electric potential with time, the apparent polarization rate and apparent charge rate of the underground medium can be inverted, which is used to infer the location, range and grade variation of the underground ore body.

[0003] The traditional induced polarization method mainly uses surface devices, which is limited by factors such as terrain, geoelectric environment and depth attenuation, and it is difficult to obtain deep geological information. In order to overcome the above limitations, researchers have proposed well-induced polarization method, and developed two forms of "well-induced polarization method" and "well-to-well induced polarization method". Among them, "well-to-well induced polarization method" refers to a method for obtaining deep electrical property change information around the ore body by arranging current source and potential measurement device between underground boreholes. This technology improves the detection depth, resolution and target control accuracy, and is especially suitable for deep or covered metal ore exploration.

[0004] Well-to-well induced polarization method has high precision and depth advantage in theory, but when it is actually applied to specific types of deposits such as manganese ore, there are still some technical bottlenecks. First, manganese ore bodies are mostly distributed in layers or lenses, and the induced polarization anomaly intensity is weak, the signal and background contrast is insufficient, which leads to blurred imaging. Second, most of the manganese minerals (such as pyrolusite, hard manganese, manganese oxide, etc.) are semiconductor type minerals, and their surface polarization ability is not as strong as that of metal sulfides, so it is difficult to produce significant secondary field response. In addition, the surrounding rock of manganese ore is mostly sandstone, shale and other low polarization background media, which further weakens the recognition degree of induced polarization effect.

[0005] Although the existing technology attempts to improve signal quality by increasing current source power and optimizing electrode distance layout, it still does not fundamentally solve the problem of weak manganese induced polarization response. SUMMARY

[0006] To solve the above problems, the application provides a method for exploring manganese ore based on well-to-well induced polarization technology, which comprises the following steps:

[0007] Step 1, arranging a current injection well and a potential measurement well in a target mining area;

[0008] Step 2, use high-pressure hydraulic fracturing technology to expand the fracture network of surrounding rock in the target well section;

[0009] Step 3, inject salt water into the fractured section;

[0010] Step 4, sample and analyze the induced electric signal of the interwell bottom layer.

[0011] The well-to-well induced electric method applies a periodic induced electric current between underground boreholes to excite the electrochemical polarization effect between underground minerals and surrounding rock. After the current is interrupted, the decay signal of the secondary electric field is collected to obtain the apparent polarization rate and discharge time constant of the ore body, which is used to identify the mineral enrichment area with induced electric effect. This method is particularly suitable for mineral exploration under deep or complex overburden, and can provide higher resolution and deeper detection depth than surface induced electric method.

[0012] The present application enhances the induced electric response of manganese ore body by introducing high-pressure hydraulic fracturing and salt water injection measures based on well-to-well induced electric method. Specifically, hydraulic fracturing forms a through fracture network in the target well section, improving the seepage channel of salt water and electric charge; the injected salt water increases the formation conductivity, reduces the dispersion speed of polarization charge, and at the same time enhances the action strength of electric field on the surface of the ore body, thereby exciting more significant polarization behavior. In addition, the salt water-mineral contact surface formed on the fracture interface is conducive to the establishment of electric double layer structure, enhancing the charge retention and release process on the surface of the ore body, ultimately improving the amplitude and duration of the secondary electric field, and improving the identification ability of induced electric method for manganese ore.

[0013] Further, in step 1, both the current injection well and the potential measurement well are multiple, forming a multi-angle and multi-directional induced electric field distribution and potential collection network in the target mining area. Compared with the traditional single-well pair induced electric device, this multi-well layout can achieve more comprehensive spatial coverage, enhance the perception of underground electrical changes, and improve the resolution of manganese ore body position, shape and size. In addition, multi-channel measurement helps to suppress local anomaly noise, improve data stability and inversion accuracy, making the induced electric response imaging clearer and more reliable, and enhancing the identification effect of complex ore body structure.

[0014] Further, step 2 further comprises high-pressure hydraulic fracturing in the formation between the current injection well and the potential measurement well.

[0015] Further, high-pressure hydraulic fracturing uses an inflatable downhole fracturing device and induces fractures through high-pressure nozzles distributed in a spiral pattern, which helps to build a more connected fracture channel network between the two wells, improving the continuity of the induced electric signal conduction and response area. Through the expansion of the fractures, not only is the injection and distribution of the current in the target formation enhanced, but also the subsequent injection of brine and functional particles can form a uniform coverage between the wells, improving the polarization effect of the ore body surface and the fracture interface, thereby enhancing the action strength and spatial response consistency of the induced electric field in the target area, expanding the recognition range of the induced electric anomaly of the manganese ore, and improving the signal strength and imaging accuracy.

[0016] Further, controlling the mass concentration of the brine in the range of 0.01-0.5% can ensure the improvement of the conductivity while avoiding problems such as particle agglomeration, decreased formation permeability, or electrode polarization distortion caused by excessive salt concentration. The brine with the appropriate concentration can enhance the ion migration ability of the formation medium, improve the electrochemical environment of the ore body surface, and promote the formation of electric double layers, thereby improving the polarization ability of the ore body and the induced electric response strength.

[0017] Further, the brine is injected in a pulsed manner, which is conducive to the formation of periodic pressure fluctuations and fluid disturbances in the fracture network, thereby promoting the deep penetration and diffusion of the brine in the micro-fractures, improving the injection efficiency and coverage uniformity. At the same time, pulsed injection can avoid the problems of local saturation and seepage short circuit caused by continuous injection, and enhance the contact probability and interfacial reactivity of the brine and the ore body surface, which helps to form a stronger electric double layer structure. In addition, pulsed disturbance can also induce the redistribution of particles on the fracture wall surface, which can improve the sensitivity and stability of the subsequent induced electric response, thereby enhancing the identification effect of the manganese ore body.

[0018] Further, in step 4, a periodic square wave current is injected into the current injection well using a direct current power source, which helps to excite clearer and more controllable induced electric response signals. The square wave current has clear current mutation boundaries and steep rising edges, which can produce strong polarization and depolarization processes at the moment of current opening and closing, making the electrochemical differences between the ore body and the surrounding rock more pronounced. At the same time, the repeated excitation of the periodic square wave can realize multiple measurements superimposed, improving the signal-to-noise ratio and data stability of the signal, which is convenient for analyzing the polarization rate, discharge time and other parameter characteristics of the ore body, thereby improving the accuracy of manganese ore body identification and imaging resolution.

[0019] Further, the presence of titanium dioxide nanoparticles in the brine can further enhance the electrochemical polarization effect on the surface of the manganese ore body, thereby improving the detection sensitivity of the induced polarization method. Specifically, titanium dioxide is a typical n-type semiconductor nanomaterial with good charge capture and storage capacity. When it is injected into the fissure with brine and adsorbed on the surface of the ore body or surrounding rock, it can form a nanoscale heterojunction structure on the mineral surface, enhancing the interface charge separation and retention capacity, and prolonging the polarization discharge process. In addition, the high specific surface area of nanoparticles is conducive to the formation of a dense electric double layer system in the microstructure of the ore body, improving the interface polarization response amplitude. In combination with the conductivity enhancement effect of the brine, the introduction of titanium dioxide particles makes the induced polarization signal stronger and decays more slowly, thereby highlighting the abnormal response of the manganese ore body in a low polarization background, improving the detection contrast and resolution, and solving the technical problems of weak induced polarization signal and difficult identification of manganese ore.

[0020] Further, after step 3, a brine suspension of titanium dioxide nanoparticles is further injected into the fractured section, i.e., a step-by-step injection strategy of "brine first, then nanoparticle suspension" is adopted, which helps to improve the deposition efficiency of particles on the surface of the ore body and the induced polarization enhancement effect. Specifically, the first injection of brine can improve the conductivity environment of the fractured section, remove gas or impurities in the fissure, establish a uniform and continuous liquid channel, and reduce the interface impedance, laying a foundation for the smooth transport and distribution of subsequent particles; the subsequently injected titanium dioxide nanoparticles are more easily permeated into the fine fissure in the pre-formed high-conductivity channel, and form stable heterojunction structures and electric double layer interfaces on the mineral surface, enhancing the polarization response. This sequential injection method avoids the problem of reduced deposition rate due to the first injection of particles being washed away or agglomerated, while improving the controllability and uniformity of the interface reaction, ultimately achieving significant enhancement of the induced polarization signal of manganese ore and improvement of the identification ability.

[0021] Further, the particle size of titanium dioxide nanoparticles is controlled in the range of 20-50 nanometers, which ensures stable dispersion and good fluidity of the particles, while achieving efficient adsorption on the surface of the ore body and electrochemical enhancement effect. A particle size that is too large limits the entry of particles into fine fissures and mineral micropores, reducing the deposition coverage; a particle size that is too small is prone to agglomeration, sedimentation or being carried away by seepage, affecting the uniformity of distribution and interface activity. The particle size range of 20-50 nanometers has a moderate specific surface area and good colloidal stability, which can be stably suspended, deeply penetrated and firmly attached to the surface of the manganese ore body during the injection process, building a heterojunction interface and an electric double layer structure, enhancing the charge retention and polarization capacity, thereby improving the strength and duration of the induced polarization response signal, and enhancing the identification sensitivity and imaging clarity of the manganese ore body.

[0022] Further, the brine suspension of titanium dioxide nanoparticles is injected in an intermittent pulse mode, which helps to achieve more efficient particle distribution and surface adsorption effect on the ore body in the formation fracture. Pulse injection can produce fluid dynamic fluctuations in a short time, break the particle deposition inertia in the boundary layer of the fracture, and promote the nanoparticles to penetrate deeply into the microfracture and mineral micropore structure, thereby expanding the action interface; intermittent injection provides a residence time for particle adsorption under static conditions, which helps the particles to form a uniform and dense heterojunction and electric double layer structure on the surface of the manganese ore. In addition, this injection method can prevent particle aggregation or loss caused by continuous delivery, improve the utilization efficiency of the suspension and the stability of the interface reaction, and ultimately enhance the polarization effect and improve the strength and recognition resolution of the induced polarization signal of the manganese ore.

[0023] Further, during the injection of the brine suspension of titanium dioxide nanoparticles, a low-voltage direct current electric field is applied between the current injection well and the potential measurement well to guide the charged particles to migrate directionally under the action of the electric field and deposit on the surface of the manganese ore body. Titanium dioxide nanoparticles usually have a certain surface charge and can overcome the irregularity of Brownian motion and fluid disturbance under the driving of the low-voltage direct current electric field, realizing the ordered movement towards the target area and improving the enrichment efficiency and deposition selectivity of the particles inside the fracture. At the same time, the electric field action helps to enhance the electrochemical coupling reaction between the particles and the ore body interface, promote the formation and stability of the heterojunction and electric double layer, and improve the strength and persistence of the induced polarization effect. This measure improves the utilization efficiency of the particles and the polarization enhancement effect, further strengthens the recognition ability and detection accuracy of the induced polarization method for manganese ore.

[0024] The beneficial effects of the present application are:

[0025] (1) The present application expands the fracture network of the surrounding rock by implementing high-pressure hydraulic fracturing in the target well section, improving the permeability of the formation. Then, the brine is injected to enhance the current conduction path and improve the conductivity of the formation and the polarization ability of the ore body surface. This combination strengthens the response strength and spatial distribution uniformity of the induced polarization signal, lays a foundation for subsequent high-resolution detection, and solves the problem of weak induced polarization anomaly and low signal-to-noise ratio of manganese ore.

[0026] (2) The present application further implements high-pressure hydraulic fracturing between the current injection well and the potential measurement well, which helps to build well-connected fracture channels between the wells and form a stable current injection and signal conduction path. This design can expand the induced polarization response area, improve the continuity and uniformity of the electric field effect between the wells, and thereby enhance the imaging ability and spatial resolution for deep or heterogeneous manganese ore bodies.

[0027] (3) The application adds titanium dioxide nanoparticles in the salt water, uses the high specific surface area and charge capture characteristics to form a heterojunction and an electric double layer structure on the surface of the ore body, and enhances the polarization discharge effect. The measure improves the induced polarization response strength and duration, is especially suitable for enhancing the identification of manganese mines with weak induced polarization anomalies, improves the ore body imaging contrast and spatial resolution, and overcomes the limitation of insufficient sensitivity of the traditional induced polarization method.

[0028] (4) The application adopts the injection strategy of "first injecting salt water and then injecting nanoparticle suspension", first cleans the channel with salt water and improves the permeability conditions, and then injects the nanoparticles in the suspension in a targeted manner to avoid particle agglomeration or loss. The sequence optimizes the deposition efficiency and distribution uniformity of the particles on the surface of the ore body, enhances the interface electrochemical coupling effect, and further enhances the induced polarization response signal and detection clarity of the manganese mine.

[0029] (5) The application applies a low-voltage direct current electric field in the process of injecting the nanoparticle salt water suspension, drives the charged particles to migrate to the surface of the manganese mine under the action of the electric field, improves the deposition selectivity and utilization rate thereof. The measure promotes the particles to be more efficiently gathered on the target interface, strengthens the formation of the heterojunction and the electric double layer, and then enhances the polarization reaction process, improves the induced polarization signal strength, and improves the spatial response accuracy of the ore body distribution.

[0030] In combination with the above beneficial effects, the application has good application prospects in the manganese mine exploration technology field. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 is a schematic diagram of a method for exploring a manganese mine based on well-to-well induced polarization technology.

[0032] Figure 2 is a schematic diagram of another method for exploring a manganese mine based on well-to-well induced polarization technology. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below with reference to the drawings and examples.

[0034] Example 1

[0035] The present embodiment provides a method for exploring a manganese mine based on well-to-well induced polarization technology, as shown in Figure 1 , which includes four steps:

[0036] Step 1, arranging current injection wells and potential measurement wells in a target mining area.

[0037] Specifically, within the exploration zone of the target manganese mine, a plurality of current injection wells and a plurality of potential measurement wells are first laid out to achieve multi-dimensional response detection of the underground electrical field. The depth of each borehole is selected according to the burial depth of the target ore body, and is generally 300-600 meters, with a bore diameter controlled between 100 mm and 150 mm. After the borehole is completed, a steel or high-strength polyethylene casing is installed, and thorough hole cleaning is performed to remove wall residues and bottom sediments, ensuring contact and signal stability for subsequent electrode installation.

[0038] In the current injection well, a cylindrical metal electrode with strong corrosion resistance, such as a graphite rod or a 316L stainless steel rod, is selected as the current injection electrode, with a diameter of generally 20 mm and a length of 0.5 to 1.0 meters. The electrode is laid out at 3-10 meters above the target fracture section, fixed in the well through a flexible support structure, and ensures directional contact between the electrode and the well wall. To prevent current leakage and external interference, the electrode and cable connection part is packaged with insulating rubber, and corrosion-resistant and pressure-resistant cables (such as YFFB type) are used, with double-layer PVC or HDPE insulation protection pipes. To improve the contact conductivity between the electrode and the formation, low-resistance salt slurry or polymer conductive slurry is injected around the electrode, and a sealed gland and cable fixing structure are provided at the wellhead to prevent water ingress and disturbance.

[0039] In the potential measurement well, a non-polarized electrode is installed to obtain accurate and stable induced polarization signals. A copper-copper sulfate electrode is usually selected, with a liquid-permeable ceramic head or sand core end on the electrode surface for full contact with the formation potential. 2-3 electrode points are laid out in each measurement well, corresponding to the target layer and shallow background positions respectively, forming a vertical profile potential monitoring. The electrode is suspended in the well through a nylon rope or an insulating cable, with a weight at the bottom to maintain vertical stability. Saturated copper sulfate solution mixed with fine sand is injected around the electrode to enhance the interface stability and long-term electrode performance. Shielded wire is used for the measurement cable, which is connected to the ground induced polarization signal acquisition system and is connected to the wellhead junction box through a waterproof joint to ensure reliable connection.

[0040] The entire well pattern system cooperates with the multi-channel direct current induced polarization instrument, and forms a multi-directional channel structure between the current injection well and the potential measurement well, to obtain stable polarization rate and discharge time constant parameters under periodic current excitation, providing an accurate basis for subsequent fine positioning and anomaly recognition of manganese ore bodies. To reduce noise interference, all wellhead cable wiring adopts zoning shielding, grounding protection and signal isolation measures. The electrode layout scheme in the well takes into account signal accuracy, structural stability and engineering operability, laying a solid foundation for the implementation of high-resolution well-to-well induced polarization method detection.

[0041] Step 2, use high-pressure hydraulic fracturing technology to expand the fracture network of the surrounding rock in the target well section.

[0042] Specifically, in the implementation process of using the well-induced electric technology for manganese ore exploration, high-pressure hydraulic fracturing is carried out on the target well section to expand the fracture network of the surrounding rock and improve the penetration channel of the liquid and the current. The present application selects the stratum with a burial depth of about 250-400 meters as the fracturing section, and the fracturing position is adjacent to the target manganese ore body or its overburden, so as to realize the coverage of the induced electric response zone. In order to realize the expansion of the fracture in a specified position and direction, an inflatable downhole fracturing device is arranged inside the target well section. The device can be inflated and isolated at the specified depth section by hydraulic control, thereby limiting the leakage and diffusion of the fracturing fluid.

[0043] The fluid used in the fracturing operation is treated clear water, which has good pressure transmission performance and environmental compatibility. The fracturing pump is set to an injection pressure of 20-30 MPa, which is dynamically adjusted according to the strength of the stratum and the fracture extension. The duration of a single fracturing is 5-10 minutes, and the operation time and liquid volume are flexibly controlled according to the response of the stratum. During the fracturing process, the fracturing device is continuously supplied with liquid through the ground high-pressure manifold, and the ground pressure, liquid injection flow and stratum back pressure are monitored in real time.

[0044] In order to induce the fracture to extend in a favorable direction and form a fracture network with stronger connectivity and wider coverage, a plurality of high-pressure nozzles are arranged along a spiral line on the periphery of the fracturing device shell. The nozzles are made of high-pressure stainless steel material, with a hole diameter of 1-2 mm. Each nozzle is arranged at an angle of about 45 o The deflection angle is arranged towards the well wall, ensuring that the high-pressure fluid impacts the well wall in a tangential manner, weakening the local structure of the well wall and promoting the opening of the fracture along the spiral path. The spiral arrangement of the nozzles not only increases the complexity of the fracture expansion direction, but also improves the fracture intersection density, which is beneficial to the uniform penetration and distribution of subsequent brine and functional particles.

[0045] In addition, in order to avoid damage to the stratum structure caused by excessive fracturing, the fracturing device system is equipped with a pressure relief valve and a backflow monitoring module to timely release pressure and recover fracturing residual liquid through the ground back pressure or back pumping system after fracturing is completed. The entire fracturing system has good control accuracy, liquid injection uniformity and safety, providing ideal structural channels and fluid field conditions for enhancing the induced electric response. The design of the specified and directional fracturing improves the detection accuracy and data resolution of the manganese ore body.

[0046] Step 3, injecting brine into the fracturing section.

[0047] Specifically, after the completion of high-pressure hydraulic fracturing operations and the confirmation of the fracture network expansion, a saltwater solution injection operation is performed to further enhance the fracture conductivity and the ore body induced polarization response capability. In this embodiment, the saltwater used is a 0.1% mass concentration sodium chloride (NaCl) solution, which is prepared by dissolving industrial purity NaCl and deionized water in proportion, fully and uniformly mixed by stirring, and stored in a stainless steel or corrosion-resistant plastic liquid tank for standby, ensuring that the solution is pure, stable in concentration, and free of impurities.

[0048] The saltwater injection is controlled by a ground injection device, using a high-pressure variable frequency injection pump connected to the wellhead injection pipeline system, with a stable injection rate of 5 liters per minute. In order to achieve uniform penetration and micro-fracture expansion in deep layers, the injection mode is designed as pulse intermittent injection: every 5 seconds of injection, pause for 10 seconds, forming periodic shock waves and penetration driving, which is beneficial to break the air blockage and capillary resistance effect that may exist in the fractures. This pulse injection strategy improves the migration ability of saltwater in complex fracture networks, enhancing the range and efficiency of its contact with the ore body.

[0049] The duration of the entire injection process is dynamically adjusted according to the length of the well section and the permeability of the formation, controlled between 30 to 60 minutes, and the total injection volume is evaluated based on the fracture volume of the fractured section, usually 300-800 liters. To prevent liquid backflow and upward flow, a one-way check valve is installed at the wellhead, and a liquid level monitoring and pressure release device is equipped at the top of the wellbore to realize real-time monitoring of the injection pressure and liquid distribution state.

[0050] In addition, to improve the ion exchange efficiency of saltwater with the surface of the manganese ore body, the injection pressure can be appropriately increased by 2-3 MPa in the initial stage of injection for "pre-flushing" the fracture wall of the well section, removing residual drilling fluid and debris, and then switching to normal pressure pulse mode for stable injection, ensuring that the saltwater forms a stable electrolyte environment on the surface of the ore body. This saltwater injection scheme is simple in process, precise in control, and strong in adaptability, providing ideal electrochemical conditions for the subsequent delivery of functional particles and the excitation of electrode response.

[0051] Step 4, sampling and analyzing the induced polarization signals of the interwell bottom layer.

[0052] Specifically, after the saltwater has been stably infiltrated and fully wetted the target fracture network, the well-to-well induced polarization data acquisition system is started, and the polarization response of the manganese ore body area is quantitatively recorded and analyzed. The entire testing process adopts a well-to-well induced polarization arrangement, that is, periodic current excitation is applied in multiple current injection wells, and response signals are simultaneously collected in multiple potential measurement wells, thereby constructing a three-dimensional electrical model.

[0053] The power system selects a high-stability direct-current induced electric power source, and the output waveform is a symmetrical bipolar square wave. This waveform can eliminate the influence of electrode polarization and improve the accuracy of induced electric parameters. The current excitation amplitude is set to 20-50 mA, which is adjusted according to the formation resistivity and electrode contact resistance; the frequency is set to 0.1-0.5 Hz to ensure that the signal has sufficient charging and discharging time and to enhance the resolution of polarization parameters such as apparent polarization rate and time constant. The current excitation sequence adopts a multi-injection well sequential or rotating excitation strategy, that is, different injection wells are excited in a predetermined cycle sequence to avoid electric field interference caused by energy concentration and to improve the spatial distribution density of data.

[0054] On the measurement side, the non-polarized electrodes in multiple potential wells are connected through a multi-channel data acquisition host. The acquisition system synchronously records the secondary electric field decay curves of different measurement points after the excitation current is turned off, which are used to calculate the polarization parameters. The system sampling rate is set to 100 times per second (100 Hz) to capture the entire process of potential change after excitation interruption and to avoid signal loss or distortion. Each round of current excitation time is not less than 300 seconds, including at least one complete excitation-power-off-decay cycle, to ensure that the obtained polarization signal has good invertibility and stability.

[0055] During the entire test process, a high-precision clock synchronization module is provided to ensure that the time references of all channels are consistent. At the same time, the excitation waveform, current amplitude, electrode contact state, and environmental interference are monitored and dynamically corrected in real time through the ground control system. To reduce the influence of ground stray current or surrounding electromagnetic noise on the acquisition results, shielded twisted pair cables are used for laying the acquisition lines, and an independent grounding system is set up, with the system grounding resistance controlled within 5 ohms.

[0056] The finally obtained induced electric data will be imported into professional inversion software to conduct three-dimensional apparent polarization rate modeling combined with a geological model, identify the distribution boundary and electrical characteristics of the manganese ore body, and improve the accuracy of ore body identification under complex geological conditions. This design scheme takes into account the excitation stability, signal acquisition density, and data inversion reliability, and provides a high-quality data basis for deep or low-polarization manganese ore exploration.

[0057] Example 2

[0058] On the basis of Example 1, to further improve the interwell fracture connectivity, enhance the permeation effect of salt water and functional particles, and optimize the induced electric signal transmission path, this example adds a formation fracturing operation between the current injection well and the potential measurement well after the original target well section fracturing is completed.

[0059] Specifically, a pair of representative well groups is selected as the test section, the well group spacing is 100 meters, and the formation thickness is about 350 meters. An auxiliary fracturing well is arranged in the middle of the formation between the two wells (about 280-320 meters from the ground surface). A horizontal formation fracturing operation is performed using an expanding bidirectional fracturing device. The fracturing operation still uses clean water as the fracturing fluid, the fracturing pressure is set to 25 MPa, the single fracturing lasts for 8 minutes, and the total liquid injection volume is about 600 liters. In order to induce the crack to extend in the direction of the connecting line between the injection well and the measuring well, two rows of symmetrical spiral nozzles are arranged on the outer shell of the fracturing device, the spacing between each row of nozzles is 30 degrees, and the jet angle is 45 o The crack is inclined to the well wall, forming a crosswise crack induction path, and improving the crack intercommunication rate. After fracturing, well wall cleaning and pressure stabilization treatment are performed. After the formation pressure is stabilized, the saltwater solution is injected in the manner of example 1, and the pulse injection parameters and time are consistent.

[0060] In this embodiment, high-pressure hydraulic fracturing is performed on the formation between the current injection well and the potential measuring well, which enhances the connectivity and permeability of the interwell crack network, establishes a more uniform and low-impedance current transmission channel, and improves the symmetry and stability of the induced polarization field distribution. The newly formed cracks significantly increase the specific surface area of the saltwater and the ore body, enhance the interface polarization and double-layer effect, and thus improve the strength and duration of the induced polarization response. At the same time, the establishment of the multi-channel current path helps to improve the collection accuracy and inversion resolution of the polarization signal, synchronously enhances the identification ability and imaging clarity of the manganese ore body, and optimizes the application effect of the well-to-well induced polarization method under complex formation conditions.

[0061] Example 3

[0062] Based on example 2, this embodiment further improves the injection liquid formula, directly disperses titanium dioxide (TiO2) nanoparticles in the saltwater solution to form a functional composite liquid, and injects it into the target crack section formed by fracturing, in order to enhance the polarization response signal of the manganese ore body and improve the amplitude and clarity of the electrical anomaly.

[0063] Specifically, first, prepare saltwater with a NaCl mass concentration of 0.1%, and at room temperature, add TiO2 nanoparticles with a particle size of 30 nanometers, with an addition ratio of 0.5 grams of nanoparticles per liter of saltwater. To prevent particle agglomeration, high-speed shearing stirring is used for 30 minutes during mixing, and ultrasonic dispersion treatment is performed for 15 minutes, so that the nanoparticles are uniformly and stably suspended in the saltwater to form a milky white nanosuspension. The prepared mixed liquid is stored in a sealed container and immediately injected into the well for use, to avoid particle settling caused by long-term standing.

[0064] The injection process is in the manner of example 2, using pulse injection strategy (5 seconds injection, 10 seconds pause), injection rate is controlled at 5 liters per minute, the total injection amount is controlled at 300-800 liters according to the target fracture section capacity. Due to the small particle size of TiO2 nanoparticles and the active surface electrical properties, it can form a heterojunction or electric double layer structure with the surface of manganese ore, and improve the local polarization ability. Compared with the traditional injection of brine, the composite liquid not only retains the good electrolytic performance of brine, but also introduces a controllable interface polarization enhancement mechanism. The nanoparticle composite brine scheme can enhance the exploration effect without increasing the complexity of construction, and the method has good practicality and popularization value.

[0065] Example 4

[0066] On the basis of example 2, in order to further improve the polarization intensity of manganese ore body and the electrical anomaly recognition ability, this example adopts a step-by-step injection strategy, that is, after completing the injection of brine, further inject the saltwater suspension of titanium dioxide nanoparticles into the target fracture section, and apply a low-voltage direct current electric field between the current injection well and the potential measurement well during the injection process, so as to induce the directional migration of the particles and enhance the interface action of the particles with the surface of the ore body.

[0067] First, complete the fracturing operation according to example 2, and pulse injection of brine with a mass concentration of 0.1% NaCl is performed to ensure that the fracture network is fully wetted and pretreated. After the injection of brine, wait for 10-20 minutes to allow it to be stably distributed in the fracture and preliminarily form a conductive channel with the ore body. Then, the injection of the saltwater suspension of titanium dioxide nanoparticles is started. The suspension is prepared as follows: deionized water is used as the solvent, 0.1% NaCl is added to maintain the same electrical conductivity as the previous brine, and TiO2 nanoparticles with a particle size of 20-50 nanometers are added at a concentration of 0.5 grams per liter. In order to prevent particle agglomeration, ultrasonic oscillation is used for 20 minutes, and the suspension state is maintained until injection. The injection process adopts intermittent pulse injection: 5 seconds injection, 10 seconds pause, for 30 minutes, and the total injection amount is controlled between 300-500 liters. The pulse injection method can promote the deep diffusion and stratified deposition of the particles in the fracture network, and reduce the premature settlement or accumulation of the particles to block the fracture. During the injection, a low-voltage electric field with a voltage difference of about 5-10 volts is applied between the current injection well and the potential measurement well, with the same polarity as the square wave excitation power source, to guide the negatively charged or dipole distributed TiO2 particles to migrate to the surface of the manganese ore along the direction of the electric field. This electric field induction mechanism improves the directional deposition efficiency and surface adhesion ability of the particles, and helps to form more stable heterojunction and electric double layer structure at the ore-solution interface. The way of collecting induced polarization data is the same as example 2, using symmetric bipolar square wave current excitation, the sampling frequency is 100 Hz, and the excitation time is not less than 300 seconds.

[0068] Example 5

[0069] On the basis of Example 4, in order to further enhance the electrical adsorption effect of titanium dioxide nanoparticles on the surface of manganese ore, improve the quality of heterojunction formation and the strength of induced polarization response, a method of introducing calcium ions (Ca 2+ ) into the suspension was used for injection treatment. The specific steps are as follows:

[0070] First, a titanium dioxide nanoparticle brine suspension was prepared, the mass concentration of the brine used was 0.1% NaCl, the mass concentration of TiO2 nanoparticles was 0.5 g / L, and the particle size range was controlled at 20-50 nm. Subsequently, 0.05% mass concentration of calcium chloride (CaCl2) was added to the suspension as a source of calcium ions. To enhance the dispersion stability of the particles in the solution, 0.05% polyvinyl alcohol (PVA) can be added as a dispersant, and a uniform and stable composite suspension is obtained after sufficient ultrasonic dispersion.

[0071] The TiO2 suspension containing Ca 2+ was injected into the target fracture section that had been fractured and injected with brine in an intermittent pulse mode, with an injection rate of 5 liters per minute, a pulse injection rhythm of "5 seconds of injection, 10 seconds of intermittent", and a duration of 30-40 minutes. During the injection, a low-voltage direct current electric field with an intensity of 2-5 V / m was applied between the current injection well and the potential measurement well to guide the co-migration of negatively charged nanoparticles and calcium ions and promote the directional deposition of particles on the surface of the ore body.

[0072] After the injection was completed, the induced polarization response signal was collected according to the method of Examples 1-4, and multi-channel potential measurement and inversion analysis were performed.

[0073] In this example, calcium ions, as divalent cations, can neutralize the electrostatic repulsion between TiO2 particles and the surface of manganese ore, form an electrical bridging structure between them, enhance the directional adsorption and stable deposition of particles; at the same time, Ca 2+ adjusts the interface charge distribution, promotes the accumulation of polarization charges and the formation of heterojunction, thereby improving the response strength and recognition ability of the well-to-well induced polarization method for manganese ore bodies.

[0074] In summary, the application provides a method for exploring manganese ore based on well-to-well induced polarization technology, which combines high-pressure hydraulic fracturing, salt water regulation, nanoparticle injection and low-voltage electric field assistance and other measures to enhance the induced polarization response capability of manganese ore body. By hydraulic fracturing in the target well section, the fracture network of surrounding rock is expanded, and the permeability of the injected liquid is improved; low-concentration salt water is injected into the fractures to improve the electrolyte conductivity and enhance the polarization reaction; further introduce titanium dioxide nanoparticles and calcium ions, by constructing a stable ore body-particle heterojunction interface, to enhance the polarization intensity and signal duration; supplemented by low-voltage direct current electric field guided migration, to improve the particle deposition efficiency and response uniformity. The application as a whole improves the induced polarization identification sensitivity and spatial imaging accuracy of the manganese ore body, overcomes the technical bottlenecks of weak signal and blurred boundary in the traditional well-to-well induced polarization method in manganese ore exploration, and has distinct theoretical innovation and engineering practical value.

[0075] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for prospecting manganese ore based on borehole-borehole induced polarization technology, characterized in that, The method comprises the following steps: Step 1: arranging current injection wells and potential measurement wells in the surveying zone of the target manganese mine; the current injection wells and the potential measurement wells are both multiple, in the current injection wells, cylindrical metal electrodes with strong corrosion resistance are selected as current injection electrodes, low-resistance salt slurry or polymer conductive slurry is poured around the cylindrical metal electrodes, and sealing gland and cable fixing structure are arranged at the wellhead to prevent water ingress and disturbance; in the potential measurement wells, non-polarized electrodes are installed to obtain accurate and stable induced polarization signals, 2-3 electrode points are arranged in each potential measurement well, corresponding to the target layer and the shallow background position respectively, to form a vertical profile potential monitoring; the current injection wells and the potential measurement wells form a multi-directional channel structure, and stable polarization rate and discharge time constant are obtained under periodic current excitation, thereby providing an accurate basis for subsequent fine positioning and anomaly identification of the manganese ore body; Step 2: extending the surrounding rock fissure by using high-pressure hydraulic fracturing technology in the target well section; high-pressure hydraulic fracturing is carried out in the stratum between the current injection wells and the potential measurement wells; the high-pressure hydraulic fracturing uses an inflatable downhole fracturing device, and the surrounding rock fissure is induced through high-pressure nozzles distributed along the spiral line on the outer periphery of the inflatable downhole fracturing device shell; the stratum with a buried depth of 250-400 meters is selected as the fracturing section, and the fracturing section is located adjacent to the target manganese ore body or the overlying rock layer to cover the induced polarization response zone; Step 3: injecting salt water into the fracturing section; the salt water injection is controlled by a ground liquid injection device, and the injection mode is pulse intermittent injection to form periodic shock waves and penetration driving, which is beneficial to break the air blockage and capillary resistance effect that may exist in the surrounding rock fissure; Step 4: sampling and analyzing the induced polarization signals of the interwell bottom layer; after the salt water is stably infiltrated and fully wets the surrounding rock fissure, the well-to-well induced polarization data acquisition system is started to quantitatively record and analyze the polarization response of the manganese ore body region; the whole test process adopts the well-to-well induced polarization arrangement mode, that is, periodic current excitation is applied in multiple current injection wells, and response signals are synchronously collected in multiple potential measurement wells, so as to construct a three-dimensional electrical property model.

2. The method for prospecting manganese ore based on borehole-to-borehole induced polarization technique according to claim 1, characterized in that: The mass concentration of the salt water is 0.01-0.5%.

3. The method for prospecting manganese ore based on borehole-to-borehole induced polarization technique according to claim 1, characterized in that: In step 4, a direct current power supply is used to inject periodic square wave current into the current injection well.

4. The method for prospecting manganese ore based on borehole-to-borehole induced polarization technique according to claim 1, characterized in that: The salt water contains titanium dioxide nanoparticles.

5. The method for prospecting manganese ore based on borehole-to-borehole induced polarization technique according to any one of claims 1-4, characterized in that: After step 3, further comprising injecting a salt water suspension of titanium dioxide nanoparticles into the fracturing section.

6. The method for prospecting manganese ore based on borehole-to-borehole induced polarization technique according to claim 5, characterized in that: The particle size of the titanium dioxide nanoparticles is 20-50 nanometers.

7. The method for prospecting manganese ore based on borehole-to-borehole induced polarization technique according to claim 5, characterized in that: The salt water suspension of titanium dioxide nanoparticles is injected in the form of intermittent pulse.

8. The method for prospecting manganese ore based on borehole-to-borehole induced polarization technique according to claim 5, characterized in that: When the salt water suspension of titanium dioxide nanoparticles is injected, a low-voltage direct current electric field is applied between the current injection well and the potential measurement well.

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