Stop filling device for salt mine and anti-accumulation method thereof

Abstract

The invention relates to the technical field of salt mine collection, in particular to a stoping and filling device of a salt mine well and an anti-accumulation method of the stoping and filling device, the device comprises a butt joint well group, and the butt joint well group comprises a mud inlet well and a brine outlet well and is used for achieving backfilling of calcium magnesium mud and stoping of brine; the well logging system is used for detecting the shaft condition and the position of a cavity top plate; the pipe cutting equipment is used for cutting off the sleeve at a preset position below the top plate of the dissolving cavity; the sonar cavity measuring equipment is used for measuring the spatial form of the dissolving cavity; scale on the inner wall of the casing pipe is removed through a high-pressure water nozzle and steel wire brush composite cleaning technology, and pipe cutting position control accurate to the millimeter level is matched, so that a slurry conveying channel is unobstructed, the problem of pipeline blockage is solved, and production halt loss caused by blockage is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of salt mine collection, in particular to a salt mine recovery and filling device and an anti-accumulation method thereof. Background Art

[0002] In the process of well salt mining, drilling water dissolution is a common mining method. Solvents are injected into the well to dissolve the salt layer, forming mineral-rich brine and then extracted. At the same time, a dissolution cavity is formed underground. In order to make full use of resources and reduce environmental pollution, some salt mining companies backfill the calcium-magnesium mud produced during the brine purification process into the dissolution cavity, which not only realizes the comprehensive utilization of waste mud, but also fills the dissolution cavity, thereby improving mining efficiency. The existing industry mostly uses docking well groups for mud discharge and recovery, that is, mud is injected through one well and brine is extracted through another well to achieve continuous operation.

[0003] Since old wells have been in use for a long time, there may be problems such as casing deformation, corrosion, and scaling in the wellbore, which will cause the mud flow to be obstructed during transportation and easily form an accumulation angle at the bottom of the well, thereby blocking the pipeline. If the actual shape of the cavity and the condition of the casing are not accurately understood, blind mud discharge may cause the mud to be unevenly distributed in the cavity, resulting in excessive accumulation in some areas and failure to effectively fill other areas. This not only reduces the utilization rate of the cavity, but may also cause the cavity structure to become unstable due to increased local pressure, and even cause damage to the wellbore. Once blockage occurs, it is often necessary to re-drill the well or replace the mud discharge channel, which greatly increases the mining cost and affects production efficiency.

[0004] Therefore, in response to the above-mentioned problems of wellbore blockage, uneven mud distribution and low cavity filling efficiency, the present invention proposes a salt mine recovery and filling device and an anti-accumulation method thereof. Through precise well logging, optimized pipe cutting position and real-time monitoring of cavity morphology, the mud is ensured to be evenly dispersed and the formation of accumulation angles is effectively prevented, thereby improving the utilization rate of the cavity and reducing mining costs. Summary of the Invention

[0005] In order to overcome the problem of shaft blockage caused by the prior art, the present invention proposes a salt mine recovery and filling device and an anti-accumulation method thereof.

[0006] The technical solution of the present invention is: a salt mine recovery and filling device, comprising:

[0007] The docking well group includes mud inlet wells and brine outlet wells, which are used to realize the backfilling of calcium magnesium mud and the recovery of brine;

[0008] Well logging system, used to detect wellbore condition and cavity roof position;

[0009] Pipe cutting equipment, used to cut the casing at a preset position below the cavity roof;

[0010] Sonar cavity measurement equipment is used to measure the spatial morphology of the dissolution cavity.

[0011] Preferably, the logging system includes a natural gamma ray logging instrument, an electromagnetic flaw detector, a cementing quality detector and a fiber optic gyroscope logging instrument, which comprehensively detects the structural integrity of the wellbore and the accuracy of the cavity positioning through multi-parameters. The natural gamma ray logging instrument is used to identify the lithology of the formation, distinguish the salt layer from the surrounding rock and assist in judging the boundary of the cavity. The electromagnetic flaw detector accurately measures the corrosion degree, cracks and deformation areas of the casing through eddy current detection technology. The cementing quality detector combines CBL / VDL to evaluate the bonding condition between the casing and the formation. The fiber optic gyroscope logging instrument monitors the wellbore trajectory in real time and corrects the well inclination and azimuth data. The entire logging system adopts a modular design, and three-dimensional modeling is performed through professional software after data acquisition.

[0012] Preferably, the pipe cutting equipment includes a centralizer, a casing cutting tool and a drill collar, which are used to accurately cut the technical casing 30 meters below the top plate of the cavity. The centralizer adopts a Φ150mm rigid structure to stabilize the drill tool and center the casing cutting tool. The casing cutting tool is a hydraulically driven cutter equipped with a high-strength alloy blade. It can efficiently cut Φ177.8mm casing at a speed of 40-60r / min and a displacement of 16L / s. A drop of 2-3MPa in pump pressure during cutting indicates that the casing is broken. The drill collar provides axial pressure and transmits torque. Its Φ120mm diameter matches the cutter. The pipe cutting position is strictly selected 30 meters below the top plate of the cavity. The cut casing falls freely to the bottom of the cavity. The entire set of equipment monitors the drilling pressure, speed and pump pressure in real time through the ground control system.

[0013] Preferably, the sonar cavity measurement equipment includes a high-precision sonar probe, a data acquisition unit and a three-dimensional modeling software, which is used to comprehensively analyze the geometry of the cavity and guide mud discharge optimization. The sonar probe uses multi-beam emission technology and lowers the cable at a uniform speed of 25 meters per second. The cavity data is collected at intervals of 1 meter in the depth direction and 10° in the circumferential direction, covering the contours of the cavity top, bottom and side walls. The data acquisition unit records the sound wave reflection signal in real time and corrects the depth error in combination with the temperature, pressure and magnetic positioning curves. The three-dimensional modeling software converts the original data into the cavity volume and maximum / minimum diameter, and generates a top view, a cross-sectional view and a three-dimensional model. By comparing the changes in the cavity morphology before and after pipe cutting, the mud discharge speed and direction are dynamically adjusted to make the calcium-magnesium mud evenly fill the cavity. The equipment can also be linked with the logging system data to predict the stability of the cavity.

[0014] Preferably, the anti-accumulation method of the recovery and filling device of the salt mine includes the following steps:

[0015] S1, select the docking well group and determine the mud inlet well and brine outlet well;

[0016] S2, perform exploration, hole sweeping and hole washing on the mud well to remove scale and dirt on the inner wall of the casing;

[0017] S3, using the logging system to detect the wellbore condition and the position of the cavity roof;

[0018] S4, according to the logging results, the casing is cut at a preset position below the cavity roof;

[0019] S5, use sonar cavity measurement equipment to measure the spatial morphology of the cavity so that the mud can be evenly dispersed when falling.

[0020] Preferably, the hole sweeping and hole washing process in step S2 uses a composite cleaning technology combining a high-pressure water nozzle and a wire brush to thoroughly remove the crystallized salt, calcium and magnesium deposits and corrosion products on the inner wall of the casing through the dual effects of physical scouring and mechanical scraping. 6-10 fan-shaped water nozzles with an aperture of 10-16 mm are installed at the front end of the drill bit, and a high-pressure water flow of 15-20 MPa is used to impact the scale on the pipe wall. At the same time, a rotating wire brush is arranged at the rear of the drill bit to scrape the casing 360° without dead angles at a speed of 30-50 r / min. The cleaning fluid is a low-solid drilling fluid containing polyacrylamide. This step is continued until the return fluid is clear and free of residue, and the cleanliness is verified by downhole video or diameter gauge detection.

[0021] Preferably, the logging inspection in step S3 uses multi-dimensional data fusion analysis technology, quantifies the degree of casing corrosion by an electromagnetic flaw detector, locates the deformation area by a laser caliper, and evaluates the cement sheath bond strength in combination with the CBL / VDL logging curve; wherein the electromagnetic flaw detection uses pulsed eddy current technology to penetrate the scaling layer to detect the remaining wall thickness and identify transverse cracks and hole defects, and the fiber optic gyroscope re-measures the well inclination and azimuth with an accuracy of 0.01°, thereby constructing a three-dimensional wellbore trajectory model and correcting the cavity roof depth error to ±0.5 meters. All data are integrated in real time through the geological steering system to generate a comprehensive evaluation report of the wellbore integrity, focusing on marking high-risk sections, and providing a quantitative basis for the selection of pipe cutting positions.

[0022] Preferably, the pipe cutting operation in step S4 uses a three-stage process of "positioning-cutting-trimming". First, the cutting point is marked 1.5-2 m below the coupling based on well logging data. Then, the cutter is precisely transported to the target depth using gyroscope positioning. During the cutting stage, a hydraulic expansion cutter is used. The blade rotates at 50-60 r / min and applies a radial force of 20-30 kN. The cutter head is cooled by a drilling fluid displacement of 16 L / s. The casing is determined to be completely severed when the pump pressure suddenly drops by 2-3 MPa. Then, the process is operated in trimming mode for 20 minutes. The cut surface is polished to a 45° chamfer using a diamond milling head. The severed casing falls freely due to gravity, and sonar monitoring confirms that it is completely out of the wellbore.

[0023] Preferably, the sonar cavity measurement in step S5 implements refined grid scanning, adopts a 24-element phased array sonar probe, emits 200kHz high-frequency sound waves at a beam angle of 0.2°, and collects cavity data at intervals of 0.5m in the vertical direction and 5° in the horizontal direction. Each measuring point synchronously records the round-trip time, amplitude attenuation and Doppler frequency shift of the sound wave, calculates the topological morphology and surface roughness of the cavity wall through an inversion algorithm, introduces a machine learning algorithm during data processing, automatically identifies potential accumulation areas and marks them as red warning areas, and the final output three-dimensional model includes a dynamic change curve of the cavity volume, a thermal map of the mud settling rate and recommended mud discharge pressure parameters, which guides the operator to adjust the injection and discharge ratio so that the mud forms a flushing effect in the warning area.

[0024] Preferably, the method further comprises restoring the wellhead and well site after pipe cutting, wherein a three-stage "solid, liquid, and gas" treatment system is implemented in the wellhead and well site restoration process. The solid waste is first separated by a vibrating screen to remove drill cuttings with a particle size greater than 2 mm, and then a magnetic separator is used to recover metal debris. The remaining waste residue is solidified with cement and then landfilled in a designated mining area; the liquid waste is treated in a three-stage sedimentation tank, and the supernatant is tested to have a chloride ion content of less than 500 mg / L and then pumped into the brine extraction pipeline for recycling. An activated carbon adsorption device is installed at the gas discharge end to capture VOCs volatilized from the drilling fluid.

[0025] After the restoration, an intelligent monitoring module is installed at the wellhead to monitor the casing stress, cavity pressure and brine composition in real time. The data is transmitted wirelessly to the central control system via LoRa.

[0026] Beneficial effects of the present invention:

[0027] 1. The high-pressure water nozzle and wire brush composite cleaning technology is used to remove the scale on the inner wall of the casing. Combined with the pipe cutting position control accurate to the millimeter level, the mud conveying channel is unobstructed, solving the problem of pipeline blockage and avoiding production losses caused by blockage.

[0028] 2. Through precise well logging to locate the position of the cavity roof, combined with optimized pipe cutting technology, the mud is evenly dispersed in the cavity, effectively improving the filling rate and effectively utilizing the cavity space resources. At the same time, it reduces repeated construction caused by local accumulation, shortens the time of single well operation, and significantly improves the overall efficiency of salt mining. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 What is shown is a schematic diagram of the workflow of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0031] The present invention provides an embodiment: a salt mine recovery and filling device, comprising:

[0032] The docking well group includes mud inlet wells and brine outlet wells, which are used to realize the backfilling of calcium magnesium mud and the recovery of brine;

[0033] Well logging system, used to detect wellbore condition and cavity roof position;

[0034] Pipe cutting equipment, used to cut the casing at a preset position below the cavity roof;

[0035] Sonar cavity measurement equipment is used to measure the spatial morphology of the dissolution cavity.

[0036] The logging system includes a natural gamma ray logging instrument, an electromagnetic flaw detector, a cementing quality detector and a fiber optic gyroscope logging instrument. It uses multi-parameter comprehensive detection to detect the structural integrity of the wellbore and the accuracy of the cavity positioning. The natural gamma ray logging instrument is used to identify the lithology of the formation, distinguish the salt layer from the surrounding rock and assist in judging the boundary of the cavity. The electromagnetic flaw detector uses eddy current detection technology to accurately measure the corrosion degree, cracks and deformation areas of the casing. The cementing quality detector combines CBL / VDL to evaluate the bonding condition between the casing and the formation. The fiber optic gyroscope logging instrument monitors the wellbore trajectory in real time and corrects the well inclination and azimuth data. The entire logging system adopts a modular design. After data collection, three-dimensional modeling is performed using professional software, which can adapt to different well diameters and depths. After data collection, three-dimensional modeling is performed using professional software, which provides a reliable basis for pipe cutting and sonar cavity measurement, thereby optimizing the mud discharge path and avoiding the problem of accumulation angle blockage caused by unknown wellbore structure.

[0037] Further, the implementation of the well logging system is described:

[0038] First, select the appropriate docking well group, determine the mud well and brine well, and then conduct well cleaning operations on the mud well. Use a combination of high-pressure water nozzles and wire brushes to remove scale and corrosion products on the inner wall of the casing. Then use a logging system including a natural gamma ray logging tool, an electromagnetic flaw detector, a cementing quality detector, and a fiber optic gyro logging tool to fully detect the wellbore condition, so as to accurately determine the position of the cavity roof and the integrity of the casing. According to the logging data, a hydraulic expansion cutter is used to cut the casing 30 meters below the cavity roof to ensure that the cutting position avoids the The coupling and the centralizer are cut off to allow the casing to fall freely to the bottom of the cavity. Then, the cavity is scanned with a multi-beam sonar cavity measurement device at a vertical interval of 0.5 meters and a horizontal interval of 5 degrees to generate a three-dimensional model containing the cavity volume, top and bottom plate positions and diameter parameters. Finally, by adjusting the flow ratio of the mud inlet well and the brine outlet well, the calcium-magnesium mud is evenly dispersed and filled in the cavity. At the same time, the pressure changes in the cavity are monitored in real time. The waste generated in the whole process is recycled after solid-liquid separation and precipitation treatment, realizing efficient and environmentally friendly salt mine recovery and filling operations.

[0039] The pipe cutting equipment includes a centralizer, a casing cutting tool and a drill collar, which are used to accurately cut the technical casing 30 meters below the top plate of the cavity. The centralizer adopts a Φ150mm rigid structure to stabilize the drill tool and center the casing cutting tool. The casing cutting tool is a hydraulically driven cutter equipped with a high-strength alloy blade. It can efficiently cut Φ177.8mm casing at a speed of 40-60r / min and a displacement of 16L / s. A drop in pump pressure of 2-3MPa during cutting indicates that the casing is broken. The drill collar provides axial pressure and transmits torque. Its Φ120mm diameter matches the cutter. The pipe cutting position is strictly selected 30 meters below the top plate of the cavity.

[0040] Further, the implementation of the pipe cutting equipment is described:

[0041] First, based on the cavity roof position and casing condition data provided by the logging system, the pipe cutting position was determined 1.5-2 meters below the coupling, avoiding the centralizer. The drill string assembly, equipped with a Φ150mm centralizer, a Φ144mm casing cutting tool, and a Φ120mm drill collar, was lowered to the predetermined depth. The surface control system maintained the bit pressure at 0 and the rotation speed at 50-60 r / min, and the mud pump was started at a displacement of 16 L / s for targeted cutting. The casing was determined to be severed when the pump pressure dropped by 2-3 MPa. The tool was rotated for another 20-30 minutes to trim and polish the cut section to form a 45° chamfer. The severed casing was allowed to fall freely to the bottom of the cavity under the action of gravity. At the same time, sonar monitoring confirmed that it was completely separated from the wellbore to avoid the formation of a "door bar" shape. The bit pressure, rotation speed, and pump pressure parameters were monitored in real time throughout the cutting process to ensure the safe and efficient completion of the cutting operation and provide an unobstructed wellbore channel for subsequent mud backfill.

[0042] The sonar cavity measurement equipment includes a high-precision sonar probe, a data acquisition unit and three-dimensional modeling software, which are used to comprehensively analyze the geometric morphology of the cavity and guide mud discharge optimization; the sonar probe uses multi-beam emission technology to lower the cable at a uniform speed of 25 meters per second, and collects cavity data at intervals of 1 meter in the depth direction and 10° in the circumferential direction, covering the contours of the cavity top, bottom and side walls. The data acquisition unit records the sound wave reflection signal in real time, and corrects the depth error in combination with the temperature, pressure and magnetic positioning curves. The three-dimensional modeling software converts the original data into the cavity volume and maximum / minimum diameter, and generates a top view, a cross-sectional view and a three-dimensional model. By comparing the changes in the cavity morphology before and after pipe cutting, the mud discharge speed and direction are dynamically adjusted to make the calcium-magnesium mud evenly fill the cavity. The equipment can also be linked with the logging system data to predict the stability of the cavity.

[0043] The method for preventing accumulation of a recovery and filling device in a salt mine comprises the following steps:

[0044] S1, select the docking well group and determine the mud inlet well and brine outlet well;

[0045] S2, perform exploration, hole sweeping and hole washing on the mud well to remove scale and dirt on the inner wall of the casing;

[0046] S3, using the logging system to detect the wellbore condition and the position of the cavity roof;

[0047] S4, according to the logging results, the casing is cut at a preset position below the cavity roof;

[0048] S5, use sonar cavity measurement equipment to measure the spatial morphology of the cavity so that the mud can be evenly dispersed when falling.

[0049] The hole sweeping and hole washing process in step S2 uses a composite cleaning technology combining a high-pressure water nozzle and a wire brush to thoroughly remove crystallized salts, calcium and magnesium deposits, and corrosion products on the inner wall of the casing through the dual effects of physical scouring and mechanical scraping. 6-10 fan-shaped water nozzles with an aperture of 10-16 mm are installed at the front end of the drill bit to impact the scale on the pipe wall with a high-pressure water flow of 15-20 MPa. At the same time, a rotating wire brush is configured at the rear of the drill bit to scrape the casing 360° without dead angles at a speed of 30-50 r / min. The cleaning fluid is a low-solid drilling fluid containing polyacrylamide. This step is continued until the return fluid is clear and free of residue, and the cleanliness is verified by downhole video or diameter gauge testing.

[0050] The well logging test in step S3 uses multi-dimensional data fusion analysis technology to quantify the degree of casing corrosion through an electromagnetic flaw detector, locate the deformation area through a laser caliper, and evaluate the cement sheath bond strength in combination with CBL / VDL logging curves. The electromagnetic flaw detection uses pulsed eddy current technology to penetrate the scaling layer to detect the remaining wall thickness and identify transverse cracks and hole defects. The fiber optic gyroscope re-measures the well inclination and azimuth with an accuracy of 0.01° to construct a three-dimensional wellbore trajectory model and correct the cavity roof depth error to ±0.5 meters. All data are integrated in real time through the geosteering system to generate a comprehensive wellbore integrity evaluation report, focusing on marking high-risk sections and providing a quantitative basis for pipe cutting location selection.

[0051] The pipe cutting operation in step S4 uses a three-stage process of "positioning-cutting-trimming". First, the cutting point is marked 1.5-2 meters below the coupling based on well logging data. Then, the cutter is precisely transported to the target depth using gyroscope positioning. During the cutting stage, a hydraulic expansion cutter is used. The blade rotates at 50-60 rpm and applies a radial force of 20-30 kN. The cutter head is cooled by a drilling fluid flow rate of 16 L / s. The casing is determined to be completely severed when the pump pressure suddenly drops by 2-3 MPa. The process then operates in trimming mode for 20 minutes. The cut surface is polished to a 45-degree chamfer using a diamond milling head. The severed casing falls freely due to gravity, and sonar monitoring confirms that it has completely separated from the wellbore.

[0052] The sonar cavity measurement in step S5 implements refined grid scanning, uses a 24-element phased array sonar probe, emits 200kHz high-frequency sound waves at a beam angle of 0.2°, and collects cavity data at intervals of 0.5m in the vertical direction and 5° in the horizontal direction. Each measuring point synchronously records the round-trip time, amplitude attenuation, and Doppler frequency shift of the sound wave. The topology and surface roughness of the cavity wall are calculated through an inversion algorithm. A machine learning algorithm is introduced during data processing to automatically identify potential accumulation areas and mark them as red warning areas. The final output three-dimensional model includes a dynamic change curve of the cavity volume, a thermal map of the mud settling rate, and recommended mud discharge pressure parameters, which guides the operator to adjust the injection and discharge ratio so that the mud forms a flushing effect in the warning area.

[0053] The method also includes restoring the wellhead and well site after pipe cutting, and implementing a "solid, liquid, and gas" three-stage treatment system in the wellhead and well site restoration process. Solid waste is first separated by a vibrating screen to remove drill cuttings with a particle size greater than 2 mm, and then a magnetic separator is used to recover metal debris. The remaining waste residue is solidified with cement and then landfilled in a designated mining area; liquid waste is treated in a three-stage sedimentation tank, and the supernatant is tested to have a chloride ion content of less than 500 mg / L and then pumped into the brine extraction pipeline for recycling; an activated carbon adsorption device is installed at the gas discharge end to capture VOCs volatilized from the drilling fluid and reduce the concentration of non-methane total hydrocarbons to less than 50 mg / m 3After the restoration, an intelligent monitoring module is installed at the wellhead to monitor the casing stress, cavity pressure and brine composition in real time. The data is transmitted to the central control system via LoRa wireless.

[0054] See also Figure 1 , further, the specific workflow of the present invention is described:

[0055] First, the optimal docking well group is selected based on the mine mining data, and the pairing plan for the mud inlet well and the brine outlet well is determined. The wellhead of the selected mud inlet well is welded and repaired, and equipment is installed to ensure that the derrick, overhead crane, and vertical shaft are in a straight line and fixed with guy ropes, creating safe and stable construction conditions for subsequent operations.

[0056] A Φ152mm full-face drill bit and a Φ89mm drill pipe are used for well clearing operations. When encountering obstructions, a homemade diameter guide or spindle expander is used to deal with the deformed casing. At the same time, a drill string assembly with a high-pressure water nozzle and a wire brush is lowered to thoroughly remove scale on the inner wall of the casing by combining 15-20MPa pressure flushing and mechanical scraping until the return fluid is clear and free of residue, ensuring that the wellbore is unobstructed.

[0057] An electromagnetic flaw detector, cementing quality tester and fiber optic gyro logging instrument were sequentially lowered to conduct all-round inspections of the casing corrosion degree (accurate to percentage of wall thickness), deformation position (resolution 1mm), cementing quality (three-level evaluation of A / B / C) and wellbore trajectory (accuracy 0.01°). Through data fusion, a three-dimensional report on the wellbore integrity was generated, the position of the cavity roof was accurately located (error ±0.5 meters), and high-risk pipe sections were identified.

[0058] According to the logging data, a cutting point was set 30 meters below the top of the cavity, 1.5-2 meters away from the coupling. A hydraulic expansion cutter assembly was lowered and cutting was carried out under the conditions of 0 bit pressure, 50-60r / min rotation speed and 16L / s displacement. The pipe was cut when the pump pressure suddenly dropped by 2-3MPa. Subsequently, a diamond milling head was used to trim the cross section for 20 minutes to form a 45° chamfer to ensure that the severed casing fell freely to the bottom of the cavity without the risk of "door bar".

[0059] A 24-element phased array sonar probe is used to scan the cavity at a vertical interval of 0.5m and a horizontal interval of 5°. The cavity wall morphology is measured and the surface roughness is recorded using 200kHz high-frequency sound waves. A machine learning algorithm is used to automatically identify accumulation risk areas with a slope of less than 15°, and a three-dimensional model containing volume change curves and settlement thermal maps is output to provide a basis for optimizing mud discharge parameters.

[0060] The flow ratio of the mud inlet well to the brine outlet well is dynamically adjusted (1:1.2-1.5) according to the sonar model, forming a flushing flow in the risk area to evenly disperse the mud. At the same time, the state of the dissolution cavity is monitored in real time through the stress-pressure sensor installed at the wellhead. The data is wirelessly transmitted to the central control system via LoRa, realizing closed-loop control of the filling process.

[0061] After the operation is completed, the waste is classified and processed. The drill cuttings are separated by a vibrating screen and a magnetic separator and then solidified and landfilled. The wastewater is reused after reaching the chloride ion standard of <500mg / L through three-stage sedimentation (coarse sedimentation-flocculation-fine filtration). VOCs gas is treated by activated carbon adsorption. Finally, the well site is restored and a digital file containing construction parameters and environmental protection indicators is generated.

[0062] Furthermore, the present invention provides an embodiment, in a highly corrosive environment:

[0063] In highly corrosive mining areas where the chloride ion concentration of brine exceeds 200g / L, the present invention first uses an electromagnetic flaw detector made of 316L stainless steel to perform casing inspection, which has a corrosion resistance three times higher than that of conventional tools. During pipe cutting operations, a 5% corrosion inhibitor combination (molybdate + organic amine) is added to the drilling fluid to extend the blade life to 80 hours. The sonar measurement cavity is replaced with a titanium alloy shell probe, which can work continuously for 120 hours without failure in an acidic dissolution cavity with a pH value of 2-4, ultimately achieving safe pipe cutting and precise filling in a corrosive environment, and reducing the maintenance cost of a single well by 45%.

[0064] Furthermore, the present invention provides an embodiment, in a deep high-pressure dissolution cavity environment:

[0065] For deep-layer dissolved cavities with depths exceeding 1,500 meters and pressures reaching 25 MPa, the present invention optimizes the drill tool assembly to a Φ165mm pressure-resistant pipe cutter + a Φ102mm weighted drill pipe (total weight 18 tons). A stepped pressurization process (10 MPa→20 MPa→25 MPa, with 10 minutes of pressure stabilization at each level) is adopted during cutting. During the cavity measurement phase, a high-pressure sonar probe (rated pressure 40 MPa) is used in conjunction with a weighted cable to scan at a speed of 0.2 m / s to obtain high-precision cavity data. Finally, the pipe cutting is completed while maintaining bottomhole pressure balance. The mud filling efficiency can reach 92%, which is 37% higher than that of conventional methods.

Claims

1. A salt mine recovery and filling device, characterized in that: Includes: The docking well group includes mud inlet wells and brine outlet wells, which are used to realize the backfilling of calcium magnesium mud and the recovery of brine; Well logging system, used to detect wellbore condition and cavity roof position; Pipe cutting equipment, used to cut the casing at a preset position below the cavity roof; Sonar cavity measurement equipment is used to measure the spatial morphology of the dissolution cavity.

2. The salt mine recovery and filling device according to claim 1, characterized in that: The logging system includes a natural gamma ray logging instrument, an electromagnetic flaw detector, a cementing quality detector and a fiber optic gyroscope logging instrument. It uses multi-parameter comprehensive detection to detect the structural integrity of the wellbore and the accuracy of the cavity positioning. The natural gamma ray logging instrument is used to identify the lithology of the formation, distinguish between the salt layer and the surrounding rock, and assist in determining the boundary of the cavity. The electromagnetic flaw detector uses eddy current detection technology to accurately measure the corrosion degree, cracks and deformation areas of the casing. The cementing quality detector combines CBL / VDL to evaluate the bonding condition between the casing and the formation. The fiber optic gyroscope logging instrument monitors the wellbore trajectory in real time and corrects the well inclination and azimuth data. The entire logging system adopts a modular design, and three-dimensional modeling is performed using professional software after data acquisition.

3. The salt mine recovery and filling device according to claim 1, characterized in that: The pipe cutting equipment includes a centralizer, a casing cutting tool and a drill collar, which are used to accurately cut the technical casing 30 meters below the top plate of the cavity. The centralizer adopts a Φ150mm rigid structure to stabilize the drill tool and center the casing cutting tool. The casing cutting tool is a hydraulically driven cutter equipped with a high-strength alloy blade, which can efficiently cut Φ177.8mm casing at a speed of 40-60r / min and a displacement of 16L / s. A drop of 2-3MPa in pump pressure during cutting indicates that the casing is broken. The drill collar provides axial pressure and transmits torque. Its Φ120mm diameter matches the cutter. The pipe cutting position is strictly selected 30 meters below the top plate of the cavity. The cut casing falls freely to the bottom of the cavity. The entire equipment monitors the drilling pressure, speed and pump pressure in real time through the ground control system.

4. The salt mine recovery and filling device according to claim 1, characterized in that: The sonar cavity measurement equipment includes a high-precision sonar probe, a data acquisition unit and three-dimensional modeling software, which are used to comprehensively analyze the geometric morphology of the cavity and guide mud discharge optimization. The sonar probe uses multi-beam emission technology and lowers the cable at a uniform speed of 25 meters per second. The cavity data is collected at intervals of 1 meter in the depth direction and 10° in the circumferential direction, covering the contours of the cavity top, bottom and side walls. The data acquisition unit records the sound wave reflection signal in real time and corrects the depth error in combination with the temperature, pressure and magnetic positioning curves. The three-dimensional modeling software converts the original data into the cavity volume and maximum / minimum diameter, and generates a top view, a cross-sectional view and a three-dimensional model. By comparing the changes in the cavity morphology before and after pipe cutting, the mud discharge speed and direction are dynamically adjusted to make the calcium-magnesium mud evenly fill the cavity. The equipment can also be linked with the logging system data to predict the stability of the cavity.

5. A method for preventing accumulation of a salt mine recovery and filling device, using the salt mine recovery and filling device according to claims 1-4, characterized in that: The following steps are included: S1, select the docking well group and determine the mud inlet well and brine outlet well; S2, perform exploration, hole sweeping and hole washing on the mud well to remove scale and dirt on the inner wall of the casing; S3, using the logging system to detect the wellbore condition and the position of the cavity roof; S4, according to the logging results, the casing is cut at a preset position below the top of the cavity; S5, use sonar cavity measurement equipment to measure the spatial morphology of the cavity so that the mud can be evenly dispersed when falling.

6. The anti-accumulation method of the salt mine recovery and filling device according to claim 5, characterized in that: The hole sweeping and hole washing process in step S2 uses a composite cleaning technology combining a high-pressure water nozzle and a wire brush to thoroughly remove crystallized salts, calcium and magnesium deposits, and corrosion products on the inner wall of the casing through the dual effects of physical scouring and mechanical scraping. 6-10 fan-shaped water nozzles with an aperture of 10-16 mm are installed at the front end of the drill bit to impact the scale on the pipe wall with a high-pressure water flow of 15-20 MPa. At the same time, a rotating wire brush is configured at the rear of the drill bit to scrape the casing 360° without dead angles at a speed of 30-50 r / min. The cleaning fluid is a low-solid drilling fluid containing polyacrylamide. This step is continued until the return fluid is clear and free of residue, and the cleanliness is verified by downhole video or diameter gauge testing.

7. The anti-accumulation method of the salt mine recovery and filling device according to claim 5, characterized in that: The logging test in step S3 uses multi-dimensional data fusion analysis technology to quantify the degree of casing corrosion using an electromagnetic flaw detector, locate the deformation area using a laser caliper, and evaluate the cement sheath bond strength in combination with CBL / VDL logging curves. The electromagnetic flaw detection uses pulsed eddy current technology to penetrate the scaling layer to detect the remaining wall thickness and identify transverse cracks and hole defects. The fiber optic gyroscope re-measures the well inclination and azimuth with an accuracy of 0.01° to construct a three-dimensional wellbore trajectory model and correct the cavity roof depth error to ±0.5 meters. All data are integrated in real time through the geosteering system to generate a comprehensive wellbore integrity evaluation report, focusing on marking high-risk sections and providing a quantitative basis for pipe cutting location selection.

8. The anti-accumulation method for a salt mine recovery and filling device according to claim 5, characterized in that: The pipe cutting operation in step S4 uses a three-stage process of "positioning-cutting-trimming". First, the cutting point is marked 1.5-2 meters below the coupling based on well logging data. Then, the cutter is precisely transported to the target depth using gyroscope positioning. During the cutting stage, a hydraulic expansion cutter is used. The blade rotates at 50-60 rpm and applies a radial force of 20-30 kN. The cutter head is cooled by a drilling fluid flow rate of 16 L / s. The casing is determined to be completely severed when the pump pressure suddenly drops by 2-3 MPa. The process then operates in trimming mode for 20 minutes. The cut surface is polished to a 45-degree chamfer using a diamond milling head. The severed casing falls freely due to gravity, and sonar monitoring confirms that it has completely separated from the wellbore.

9. The anti-accumulation method for a salt mine recovery and filling device according to claim 5, characterized in that: The sonar cavity measurement in step S5 implements refined grid scanning, uses a 24-element phased array sonar probe, emits 200kHz high-frequency sound waves at a beam angle of 0.2°, and collects cavity data at intervals of 0.5m in the vertical direction and 5° in the horizontal direction. Each measuring point synchronously records the round-trip time, amplitude attenuation, and Doppler frequency shift of the sound wave. The topology and surface roughness of the cavity wall are calculated through an inversion algorithm. A machine learning algorithm is introduced during data processing to automatically identify potential accumulation areas and mark them as red warning areas. The final output three-dimensional model includes a dynamic change curve of the cavity volume, a thermal map of the mud settling rate, and recommended mud discharge pressure parameters, which guides the operator to adjust the injection and discharge ratio so that the mud forms a flushing effect in the warning area.

10. The anti-accumulation method for a salt mine recovery and filling device according to claim 5, characterized in that: The method also includes restoring the wellhead and well site after pipe cutting, and implementing a "solid, liquid, and gas" three-stage treatment system in the wellhead and well site restoration process. Solid waste is first separated by a vibrating screen to remove drill cuttings with a particle size greater than 2 mm, and then a magnetic separator is used to recover metal debris. The remaining waste residue is solidified with cement and then landfilled in a designated mining area; liquid waste is treated in a three-stage sedimentation tank, and the supernatant is tested to have a chloride ion content of less than 500 mg / L and then pumped into the brine production pipeline for recycling; an activated carbon adsorption device is installed at the gas discharge end to capture VOCs volatilized from the drilling fluid. An intelligent monitoring module is installed at the restored wellhead to monitor casing stress, cavity pressure, and brine composition in real time, and the data is wirelessly transmitted to the central control system via LoRa.

Images