Fractured stratum pipe fixing process

Abstract

The invention relates to the technical field of overlying strata separation layer grouting and drilling casing pipe fixing processes, in particular to a fractured stratum pipe fixing process which comprises the following steps that 1, equipment is installed; step 2, opening a high-pressure ball valve at an exhaust port at the top of the second-opening sleeve and an exhaust port of the first-opening sleeve during testing; 3, observing fluid at an exhaust port, pressing 1 / 2 volume of clear water into the casing pipe for back pressure cleaning, then closing the valve, and continuing to inject cement paste under pressure; 4, the pressure is monitored, and injection is stopped when the pressure naturally returns to zero; cement paste is manually mixed and supplemented to the annular space of the tops of the two casing pipes, and pipe fixing is completed until the paste supplementing pressure is stabilized for 30 min. Aiming at the characteristics of large pores and strong permeability of the fractured formation, through a dynamic adjustment strategy of firstly injecting a low-cost plugging material to plug the pores and then injecting pure cement paste, and in combination with segmented pressure control, invalid diffusion and loss of slurry towards the deep part of the formation are reduced, and accurate filling and sufficient retention of the slurry in a casing annulus and a target fracture are ensured; and the pipe fixing material loss is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of overburden separation grouting and drilling casing pipe fixing technology, and in particular to a broken stratum pipe fixing technology. BACKGROUND

[0002] With the acceleration of resource development, the safe and efficient release of coal resources under buildings, railways and water bodies (three under) has become a key problem restricting the sustainable development of mines. Under this background, overburden separation grouting technology, as one of the core paths of green mining system, can effectively control surface subsidence by accurately injecting slurry into the separation space in the overburden of mining, and simultaneously achieve the triple goals of overburden resource recovery, ecological environment protection and social stability.

[0003] The standard process of this technology includes: drilling from the ground to the target layer, and transporting the slurry prepared by the ground slurry station to the separation space through the drilling pipe to achieve the purpose of filling and subsidence reduction. The successful application of this technology is highly dependent on one prerequisite: the drilling from the surface to the deep separation zone must be stable and unobstructed. Among them, the thick loose broken zone, as a common adverse geological body, becomes the main problem of drilling and post-casing work due to its loose, broken and low mechanical strength.

[0004] Specifically, after completing the pipe-laying operation in the drilling through such strata, the conventional pipe fixing process has the following problems: 1. The fixing material is prone to loss, and the cementation quality is poor: the thick loose broken zone has high porosity and strong permeability. When ordinary cement slurry or chemical slurry is used for annular grouting and pipe fixing, the slurry will diffuse and lose in large quantities to the deep and surrounding strata, and cannot be effectively retained around the casing pipe to form a dense and complete stone body. This leads to poor pipe fixing quality and a high risk of slurry leakage.

[0005] 2. High risk of pipe column instability and difficulty in ensuring positioning accuracy: due to poor initial pipe fixing effect, during subsequent grouting construction, the pipe body is prone to sinking, deviation or even bending and breaking under the combined action of gravity, slurry upward force and stratum disturbance. Not only does this cause the grouting target to deviate from the designed layer, leading to failure of separation grouting, but it can also cause the drilling to be scrapped, resulting in serious engineering delays and safety accidents.

[0006] The traditional one-time grouting and slurry return pipe fixing method is designed for good integrity bedrock strata. For the thick loose broken zone, which is a special geological body with strong seepage and low strength, this process is not adaptable enough and cannot solve the problems of controllable accumulation and accurate sealing of slurry.

[0007] Therefore, the existing conventional pipe fixing technology has become a technical bottleneck restricting the popularization and application of overburden separation grouting technology under complex geological conditions. There is an urgent need in the field to develop a new pipe fixing process that can realize efficient plugging and reliable anchoring according to the geological characteristics of the thick loose and broken zone, and ensure the safe and efficient implementation of grouting. SUMMARY

[0008] To solve one of the above technical problems, the technical solution adopted is: a broken formation pipe fixing process, comprising the following steps: Step 1, equipment installation: drill a drilling hole, weld a grouting joint on the outer wall, open an exhaust hole, and assemble a first casing into the drilling hole; fix a guide head at the bottom of a second casing, pass the second casing into the first casing, and lower it to the target layer of the broken formation; Seal the annular space at the top of the first casing and the second casing with full welding of a steel plate, and install an integrated pressure gauge and orifice device at the top end of the first casing; The exhaust hole is higher than the grouting joint and a high-pressure ball valve is installed, the inside of the guide head is filled with cement, and a drainage hole is reserved; Step 2, connect the matching grouting pump and grouting joint, and conduct a water pressure test on the annular space of the second casing and the broken formation; open the exhaust port at the top of the second casing and the high-pressure ball valve at the exhaust hole of the first casing during the test; Step 3, observe the exhaust port fluid, if the exhaust port at the top of the second casing is self-sucking, first inject a plugging material through the grouting joint; if the exhaust hole of the first casing is liquid, close the high-pressure ball valve and inject pure cement slurry; after the pure cement slurry overflows from the valve port at the top of the first casing, wash it with 1 / 2 volume of clean water under pressure, then close the valve and continue to inject cement slurry under pressure; Step 4, monitor the pressure, stop injection when the pressure naturally returns to zero; manually mix cement slurry to supplement the annular space at the top of the two casings, and complete the pipe fixing when the supplementing pressure stabilizes for 30 minutes.

[0009] On the basis of any of the above technical solutions, further optimization is: in step 2, the water pressure test pressure is controlled by a matching pressure monitoring element to be 0.2-0.5MPa, and lasts for 15-20 minutes; if the water outflow from the exhaust ports of the two casings is uneven, check whether there is liquid leakage at the casing sealing position.

[0010] On the basis of any of the above technical solutions, further optimization is: in step 3, the plugging material is made by mixing bentonite, fly ash and water in a mass ratio of 3:1:2, the injection rate is controlled at 8-12L / min, and after the self-sucking phenomenon disappears, the pure cement slurry is injected after standing for 5-8 minutes.

[0011] Based on any of the above technical solutions, the following optimization is made: In step 3, when injecting cement grout under pressure, the pressure is less than or equal to 75%-80% of the safe bearing pressure of an open sleeve, and the pressure rise rate is controlled at 0.08-0.1MPa / min.

[0012] To prevent the casing from rupturing due to impact.

[0013] Based on any of the above technical solutions, the following further optimization is made: In step 4, the water-cement ratio of the cement grout used for patching is 0.8-1.0, the grouting rate is 5-8 L / min, and the patching pressure is maintained at 0.3-0.4 MPa.

[0014] Ensure that the annular space shrinkage gap is filled.

[0015] Based on any of the above technical solutions, the following optimization is made: In step 1, the second casing is lowered to a depth that meets the requirement that the bottom guide head is 2-3m away from the lower interface of the fractured stratum, and the casing lowering resistance is monitored by a pressure gauge during the lowering process. When the resistance exceeds 5kN, the lowering angle is adjusted.

[0016] Based on any of the above technical solutions, a further optimization is made: the matching pressure monitoring element records data every 3-5 minutes. If the pressure suddenly drops by more than 0.3 MPa, the grouting should be stopped immediately, and the sealing gasket of the grouting joint, the valve core of the high-pressure ball valve, and the pipeline interface should be checked. Grouting can only be resumed after the leak is eliminated.

[0017] The present invention also provides a pipe-stabilizing device for implementing the above-mentioned pipe-stabilizing process in fractured formations, comprising a first open sleeve, a second open sleeve, a grouting joint, a high-pressure ball valve, an exhaust port, a pressure monitoring element, an orifice device, and a guide head; A grouting joint is welded to the outer wall of the open sleeve. A high-pressure ball valve is detachably installed on the grouting joint to form a grout inlet channel. An exhaust hole is opened on the outer wall of the open sleeve 30-50cm directly above the grouting joint. A high-pressure ball valve is installed on the exhaust hole to form an exhaust / back pressure channel. A pressure monitoring element is fixedly installed at the grout inlet channel near the grouting joint. The diameter of the double-sleeve is smaller than that of the single-sleeve. The bottom of the double-sleeve is fixedly connected to a guide head by a thread. The guide head is a conical alloy steel support and is filled with cement. A drainage hole with a diameter of 5-10mm is opened on it. The orifice device is connected to the top of an open sleeve via a flange. The orifice device integrates an auxiliary pressure gauge and a shock-absorbing oil cup. The range of the auxiliary pressure gauge is not less than 1.2 times the safe bearing pressure of the open sleeve. The annular space at the top of the first and second open sleeves is sealed by welding steel plates, and the weld height is not less than 1.5 times the sleeve wall thickness.

[0018] Based on any of the above technical solutions, a further optimization is made as follows: the pressure monitoring element is an orifice wireless pressure gauge, which is connected to the slurry inlet pipeline by a threaded seal, and the seal is wrapped with polytetrafluoroethylene raw material tape to prevent slurry leakage from affecting pressure detection.

[0019] Based on any of the above technical solutions, a further optimization is made as follows: the diameter of the vent hole is 1 / 2 to 2 / 3 of the inner diameter of the grouting joint, and the inner wall of the vent hole is galvanized for corrosion protection to prevent formation water from corroding the hole wall and causing the hole diameter to increase.

[0020] Based on any of the above technical solutions, the following further optimizations are made: the bottom conical angle of the guide head is 30°-45°, the two ends of the drainage hole are rounded to prevent scraping the ground or clogging during lowering, and high-strength sealant is applied to the threaded connection between the guide head and the two-opening sleeve.

[0021] Based on any of the above technical solutions, a further optimization is made: after the weld of the annular space at the top of the first and second sleeves is completed, a 0.5MPa water pressure test must be performed. If there is no leakage after 30 minutes of pressure holding, the orifice device can be installed to ensure the sealing performance of the annular space.

[0022] Based on any of the above technical solutions, a further optimization is made: the top of the shock-absorbing buffer oil cup configured in the orifice device is provided with a vent hole, and a dust filter is installed at the vent hole to prevent dust from entering the oil cup and contaminating the anti-wear hydraulic oil, thus affecting the buffering effect.

[0023] Based on any of the above technical solutions, the following optimization is made: the welding parts of the grouting joint and the open sleeve are both made using double-sided welding process, and after welding, ultrasonic non-destructive testing is performed to ensure that there are no pores or cracks at the weld, making it suitable for high-pressure grouting conditions (pressure resistance not less than 10MPa).

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention addresses the characteristics of fractured formations with large pores and high permeability by first injecting low-cost plugging material to seal the pores and then replacing it with pure cement grout. This dynamic adjustment strategy, combined with segmented pressure control, significantly reduces the ineffective diffusion and loss of grout into deeper formations, ensuring that the grout accurately fills and is fully retained in the casing annulus and target fractures, thereby reducing the consumption of solidification materials.

[0025] 2. Pressurized grouting causes the cement grout to be tightly squeezed and broken under pressure, forming a high-strength composite solidified body of the first casing, the second casing, the grout, and the stratum. The subsequent grouting process can fill the tiny annular gaps caused by the solidification and shrinkage of the grout. At the same time, the setting of the guide head ensures the accuracy of the second casing placement, effectively avoiding problems such as sinking, displacement, or cracking of the pipe column during subsequent grouting construction.

[0026] 3. By recording data such as water pressure test pressure and live grouting pressure in real time through pressure monitoring elements, the pressure test pressure of 0.2-0.5MPa and the live grouting pressure of not exceeding 80% of the safe bearing pressure of the first casing can be clearly defined. This can promptly detect grout leakage faults with a pressure drop of more than 0.3MPa and quickly troubleshoot and deal with them, avoiding blindly applying high pressure that may cause casing breakage or formation splitting, and reducing the risk of safety accidents.

[0027] 4. Specifically designed for extremely thick, loose, and fractured zones, the construction scheme can be flexibly switched by observing the fluid state at the vent (self-priming or liquid discharge), solving the problem of poor adaptability of traditional one-time grouting return process in highly permeable strata. It can be stably applied to various loose, fractured, and complex geological conditions, and has a wider range of applications.

[0028] 5. The low-cost sealing material prepared in the early stage using bentonite, fly ash and water in a ratio of 3:1:2 significantly reduces material costs compared to using pure cement slurry directly. At the same time, due to the reliable quality of the solidified pipe, the project rework and delays caused by pipe instability and drilling failure are reduced, ensuring that the subsequent overburden separation grouting construction can be carried out efficiently according to plan and shortening the overall construction period. Attached Figure Description

[0029] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. In all the drawings, similar elements or components are generally identified by similar reference numerals. In the drawings, the elements or components are not necessarily drawn to scale.

[0030] Fig. 1 This is a schematic diagram of a fractured formation solidification process according to an embodiment of the present invention.

[0031] Fig. 2 This is a schematic diagram of the orifice device structure according to an embodiment of the present invention.

[0032] In the diagram: 1. Exhaust / backpressure port; 2. Anti-vibration buffer oil cup pressure gauge; 3. Welded part; 4. Threaded wire (top orifice device thread or flange connection); 5. Grout inlet; 6. Grout inlet / exhaust port; 7. First-opening sleeve; 8. Second-opening sleeve; 9. Grout outlet (spare); 10. Bottom exhaust port; 11. Bottom of guide head mounting sleeve; 12. Schematic diagram of grout diffusion route; 13. Compressed stratum; 14. Grout inlet anti-vibration buffer oil cup pressure gauge; 15. Anti-vibration buffer oil cup; 16. High-pressure ball valve; 17. Orifice device; 18. Ground surface. Detailed Implementation

[0033] The embodiments of the technical solution of the present invention will now be described in detail with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore merely examples and should not be used to limit the scope of protection of the present invention. The specific structure of the present invention is as follows: Figs. 1-2 As shown in the image.

[0034] To address the shortcomings of existing technologies in pipe-stabilizing in thick, loose, and fractured formations, such as easy grout loss, poor pipe-stabilizing quality, easy instability of the tubing string, and insufficient process adaptability, this invention aims to provide a pipe-stabilizing process for fractured formations. Its core objectives are: to achieve controllable and efficient filling of the target annulus space with grout, avoiding ineffective diffusion and loss; to ensure the overall stability of the first and second casings, preventing subsidence, displacement, or damage under grouting pressure and formation disturbance; and to achieve precise control of the entire pipe-stabilizing process through an integrated pressure monitoring and feedback system, ensuring the final pipe-stabilizing strength and sealing performance, and providing a reliable channel for subsequent grouting operations.

[0035] A grouting technology for fractured formations, the core of which lies in the adoption of a staged and controllable grouting strategy, the main steps of which are as follows: 1. Insert a first-stage casing into the drilled borehole. Weld a grouting joint to a specific location on its outer wall and install a high-pressure ball valve to form a grout inlet channel. Open an vent hole on the outer wall of the first-stage casing above the grouting port and install a high-pressure valve thereon as an vent / backpressure channel. Install a pressure monitoring device (such as a pressure gauge) on the grout inlet pipeline to monitor the grouting pressure in real time. Insert a second-stage casing through the first-stage casing to the target depth. Then, weld the annular space at the top of the first and second-stage casings together with a steel plate to seal them, forming a closed system. Install an orifice device at the top of the first-stage casing, which integrates a pressure gauge and a shock-absorbing oil cup, among other components.

[0036] The core of this step is to construct an integrated foundation system encompassing grout injection, venting, pressure monitoring, and sealed bearing. Each component complements the others to prepare for grouting in fractured formations. The grout injection channel, consisting of the grouting joint and high-pressure ball valve, is welded to ensure a tight seal during high-pressure grouting, preventing grout leakage and pressure loss. The vent is located above the grouting port, following the fluid dynamics principle that air rises, effectively venting air from the annulus and formation fractures, preventing air resistance from affecting grout diffusion. A pressure monitoring device collects grouting pressure data in real time, providing a basis for subsequent pressure control.

[0037] The second casing is inserted into the first casing to form a double-layer structure of casing-annular space. The top annular space is welded and sealed based on the principle that an effective pressure can only be established in a closed system, preventing pressure leakage from the top during grouting. The orifice device can use existing technology. The pressure gauge on the orifice device is used for secondary pressure calibration, and the shock-absorbing buffer cup can absorb the pressure impact during grouting, preventing the pressure gauge from being damaged by instantaneous high pressure. The overall function is to build a stable and controllable grouting carrier, providing structural support for subsequent grouting and ensuring construction safety through multi-dimensional monitoring. At the same time, the double-layer casing design improves adaptability to fractured strata.

[0038] 2. Connect the grouting pipeline and conduct a water pressure test in the annulus and fractured strata where the second casing is located.

[0039] Key judgment steps: Observe the fluid conditions at each vent. If the self-priming phenomenon at the top vent of the second casing is obvious, it indicates that the formation has a large amount of grout. At this time, low-cost sealing material can be injected for preliminary sealing. When liquid flows out of the vent of the first casing, close its valve and switch to injecting pure cement grout.

[0040] The water pressure test is based on the principle of simulating grouting conditions to test the system's sealing performance and formation permeability. By injecting clean water into the annulus and formation, the fluid state at the vent is observed to determine the formation characteristics and system integrity.

[0041] When fluid flows in the annulus and formation, if self-priming occurs at the vent at the top of the second casing, it is because the fractured formation has well-developed fissures and high porosity, forming a negative pressure suction effect, indicating that the formation has a very strong grout absorption capacity. Directly injecting pure cement grout can easily lead to a surge in cost due to excessive usage. Therefore, large fissures are first filled with low-cost sealing materials such as bentonite and fly ash to achieve preliminary sealing and seepage reduction.

[0042] When liquid flows out of the vent of the first casing, it indicates that the annular space between the second and first casings has been filled with clean water, and the shallow fractures in the formation have been filled with clean water. At this point, closing the vent allows the subsequently injected pure cement grout to flow directionally to the deep fractures in the broken formation. The core function of the water pressure test is to accurately identify the formation's grout absorption capacity and the degree of fracture development, avoiding material waste or incomplete sealing caused by blind grouting. By adopting a graded strategy of first sealing leaks at low cost and then reinforcing with pure grout, construction costs can be controlled while ensuring the sealing effect, and the sealing performance of the pipeline can be tested to identify leaks in advance.

[0043] 3. When pure cement slurry overflows from the top valve port of the casing, initiate the backpressure cleaning procedure: inject approximately half the casing volume of clean water into the casing through the top orifice device, then close the valve. This operation aims to prevent slurry backflow and blockage of the upper pipeline, and to create conditions for pressure buildup.

[0044] Continue injecting cement grout, and strictly control the grouting pressure using a pressure monitoring device to ensure it does not exceed the safe bearing pressure of the first casing and the already consolidated stratum. During this stage, the pressure remains constant to ensure that the grout is fully squeezed into the formation fractures, so that the second casing, the grout-bound rock mass, and the surrounding fractured stratum are firmly consolidated into one unit.

[0045] The overflow of pure cement slurry from the top valve indicates that the annular space and shallow formation fractures have been filled with slurry. Initiating backpressure cleaning at this point is based on the principle of hydrostatic pressure balance. Injecting 1 / 2 the casing volume of clean water creates a water column of a certain height above the casing. The density difference between the water and the cement slurry generates reverse pressure, preventing uncured cement slurry from flowing back into the upper grouting pipeline due to gravity, thus avoiding pipeline blockage and affecting subsequent construction. After closing the valve, the water column forms a pressure barrier, ensuring that subsequently injected cement slurry can only diffuse into the deep fractures of the broken formation. Controlling the pressure during pressurized grouting to not exceed the safe bearing pressure is crucial because excessive pressure can cause deformation and rupture of the casing or secondary cracking of the already partially consolidated formation. Stable, continuous pressure allows the cement slurry to fully penetrate and compact within the fractures, reducing the porosity of the slurry-bound aggregate. The purpose of this step is to achieve synergy between pipeline protection, directional pressure transmission, and full grout consolidation: back pressure cleaning ensures unobstructed pipeline flow, reserving conditions for subsequent construction; pressure control ensures construction safety and avoids structural damage; continuous pressure causes the grout to bond tightly with the fracture wall, forming a three-in-one load-bearing structure with the second-opening sleeve, the rock body, and the stratum, significantly improving the stability and load-bearing capacity of the solidified pipe.

[0046] 3. Post-grouting reinforcement stage: After the pressure in the grouting system naturally dissipates to zero, the main grouting process is complete. At this time, manually mixed cement grout is used to reinforce the tiny annular spaces in the upper part that may have been formed due to solidification shrinkage, ensuring the integrity and durability of the grouting effect.

[0047] The main grouting pressure naturally dissipates to zero because the cement grout has completed its initial solidification within the fissures, ceasing to flow. The composite of the strata and the consolidation mass no longer absorbs the grout, and the pressure within the system gradually releases after losing its support, marking the completion of the main consolidation process. However, during the cement grout solidification process, volume shrinkage occurs due to water evaporation, easily forming micro-fissures or voids in the upper annular space. If these voids are not treated, they will become channels for groundwater seepage, potentially leading to casing corrosion or loosening of the consolidation structure in the long term. Subsequent reinforcement is based on the principle of filling shrinkage voids and strengthening the top seal. The artificially mixed cement grout must have good fluidity to penetrate into the micro-voids. During the grouting process, pressure changes are observed to ensure that the voids are completely filled. The core function of this stage is to compensate for the shrinkage defects of the main grouting, forming a seamless, consolidated closed structure across the entire cross-section, preventing groundwater intrusion and extending the casing's service life. Simultaneously, the top consolidation formed by the grouting further fixes the casing position, improves the overall structure's resistance to deformation, ensures long-term stability of the consolidation effect, and adapts to the complex geological environment of fractured strata.

[0048] Specifically, the present invention includes the following specific embodiments: Example 1: To solve one of the above-mentioned technical problems, the present invention adopts the following technical solution: a process for consolidating fractured formations, comprising the following steps: Step 1, Equipment Installation: Drill a first borehole, pre-weld the grouting joint on the outer wall, pre-open the vent hole, and assemble the first casing before lowering it into the borehole; fix the guide head at the bottom of the second casing, insert the second casing into the first casing, and lower it to the target layer of the fractured stratum. The annular space at the top of the first and second open sleeves is fully sealed by welding steel plates, and an integrated pressure gauge and orifice device are installed at the top of the first open sleeve. The vent is higher than the grouting joint and a high-pressure ball valve is installed. The guide head is filled with cement and a drainage hole is reserved. Drilling a pre-drilled hole provides an installation channel for the casing. The pre-welded grouting joint and pre-drilled vent hole on the outer wall of the pre-drilled casing can avoid the complex operation of downhole welding and improve construction efficiency. The vent hole is higher than the grouting joint, which conforms to the gas-liquid separation law and ensures that gas is discharged from the top during grouting, avoiding the formation of voids by air trapped in the grout.

[0049] The guide head at the bottom of the second-stage casing adopts a conical structure, utilizing the principle of force dispersion at the tip to reduce frictional resistance with the borehole wall during lowering, facilitating precise arrival at the target layer. Cement filling inside the guide head increases its weight, improving lowering stability. Pre-drainage holes allow slurry that enters the guide head during casing lowering to drain, preventing internal slurry accumulation from affecting structural strength. The top annular space is fully welded and sealed, using continuous welds to block leakage channels and ensure no pressure leakage during grouting. An integrated pressure gauge at the orifice provides dual pressure monitoring, enhancing data reliability.

[0050] The purpose of this step is to ensure the functional compatibility of each component through prefabrication and precise positioning; the guide head design solves the problem of casing jamming in broken formations, and full welding sealing and pressure monitoring provide safety assurance for subsequent high-pressure grouting, laying the structural foundation for the smooth implementation of the entire process.

[0051] Step 2: Connect the matching grouting pump and grouting joint, and conduct a water pressure test on the annular space of the second casing and the fractured stratum. During the test, open the high-pressure ball valve at the vent at the top of the second casing and the vent at the vent of the first casing. After connecting the grouting pump and the grouting joint, clean water enters the annular space under pump pressure and permeates into the fractured strata fissures. Opening two vents allows the clean water to push out internal air, preventing air resistance from affecting the permeation range. During the water pressure test, the flow state of the clean water directly reflects the system's sealing performance and the strata's permeability: if the water flow from the vents is uniform and there is no sudden pressure drop, it indicates that the pipeline is well-sealed and the strata fissures are evenly distributed; if the water flow is obstructed or the pressure is abnormal, leaks or areas with abnormal fissure development can be quickly located. The purpose of this step is to preemptively check for sealing defects in equipment and pipelines, avoiding material waste and pressure loss caused by grout leakage during grouting; at the same time, the clean water permeation initially clears the strata fissures, creating channels for subsequent grout diffusion. Compared to direct grouting, the water pressure test can reduce the construction risks caused by system failures or sudden changes in strata, improve the controllability of the grouting process, and is a key preliminary step to ensure the quality of the solidified pipe.

[0052] Step 3: Observe the fluid at the vent. If the vent at the top of the second-opening sleeve is self-priming, inject the sealing material through the grouting joint. If the vent at the first-opening sleeve is leaking liquid, close its high-pressure ball valve and replace it with pure cement grout. After the pure cement grout overflows from the valve at the top of the first-opening sleeve, press 1 / 2 volume of clean water into the sleeve for back pressure cleaning, then close the valve and continue to inject cement grout under pressure. The self-priming of the vent at the top of the second-stage casing is due to the negative pressure zone formed by deep fractures in the broken strata, which rapidly draws in clean water, indicating a large amount of grout absorbed by the formation. At this point, bentonite, fly ash, and other sealing materials are injected, utilizing their particle size distribution to fill large fractures and reduce permeability, quickly forming a primary sealing layer and reducing the amount of pure cement grout needed subsequently. When liquid emerges from the vent of the first-stage casing, it indicates that clean water has filled the upper annular space, and the shallow fractures in the formation have been filled. After closing the valve, the pressure can be directionally transmitted to the deep fractures, and pure cement grout is injected to achieve permanent reinforcement due to its high strength and good consolidation properties. After the pure cement grout overflows, half the volume of clean water is injected. Based on the principle of hydrostatic pressure balance, the clean water column forms a reverse pressure to prevent grout backflow, while simultaneously cleaning residual grout in the upper pipeline. Continued pressurized grouting allows the grout to fully penetrate into the micro-fractures under pressure, improving the consolidation density. The purpose of this step is to balance sealing efficiency and reinforcement quality by dynamically adjusting material and process parameters: the sealing material reduces costs, pure cement slurry ensures strength, and backpressure cleaning ensures unobstructed pipelines; pressurized grouting ensures that the slurry is tightly bonded to the formation, solving the core problem of insufficient reinforcement strength in fractured formations.

[0053] Step 4: Monitor the pressure and stop injection when the pressure naturally returns to zero; manually mix cement slurry and add it to the annular space at the top of the two pipes until the slurry pressure stabilizes for 30 minutes to complete the pipe solidification.

[0054] During pressurized grouting, pressure monitoring data directly reflects the grout consolidation process: as the grout fills and solidifies within the fissures, the formation permeability decreases, and the grouting pressure gradually increases; when the pressure naturally returns to zero, it indicates that the grout has completely solidified and is no longer absorbed by the formation, marking the end of the main consolidation process. However, during the solidification of cement grout, volume shrinkage occurs due to water evaporation, forming tiny voids in the upper annular space. Artificially mixed cement grout must possess high fluidity and low shrinkage to penetrate into these voids; a stable grouting pressure for 30 minutes, based on the principle that constant pressure indicates the voids have been completely filled and there are no leakage channels, ensures a dense grouting.

[0055] The purpose of this step is to precisely control the endpoint of the main grouting through pressure monitoring, avoiding over-grouting or under-grouting; the supplementary grouting step solves the sealing defects caused by cement grout shrinkage, forming a full-section consolidation structure. Finally, through the combination of main grouting and supplementary grouting, a firm bond is achieved between the casing and the fractured strata, ensuring the long-term stability and durability of the solidified casing.

[0056] Based on any of the above technical solutions, the following optimization is made: In step 2, the pressure of the water pressure test is controlled to be 0.2-0.5MPa by the matching pressure monitoring element and lasts for 15-20 minutes. If the water output from the exhaust ports of the two sleeves is uneven, check whether there is leakage at the sleeve seal.

[0057] The pressure of the water pressure test is controlled at 0.2-0.5 MPa, which is higher than the formation hydrostatic pressure to drive fluid flow, but lower than the safe bearing pressure of the casing and the formation to avoid damage to the structure during the test. The test lasts for 15-20 minutes to allow enough time for the clean water to penetrate, ensuring that the fluid fully fills the annular space and penetrates into the shallow fractures. If there are any small leaks, they will gradually manifest as a decrease in pressure or uneven water flow during the long test.

[0058] The core reason for uneven water flow is a leak at the seal, causing some clean water to leak out instead of flowing to the vent as expected. This optimization improves the accuracy of the pressure test: a low-pressure setting avoids structural damage during the test, while a long-term test ensures that even minor defects are detected; the uniformity of water flow identifies leaks, providing a clear direction for seal repair. Compared to conventional short-duration high-pressure tests, this optimization reduces test errors, eliminates potential sealing hazards in advance, provides a more reliable safety guarantee for subsequent high-pressure grouting, and reduces construction risks.

[0059] Based on any of the above technical solutions, the following optimization is made: In step 3, the sealing material is made by mixing bentonite, fly ash and water in a mass ratio of 3:1:2. The injection rate is controlled at 8-12L / min. After the self-priming phenomenon disappears, the mixture is left to stand for 5-8 minutes before being replaced with pure cement slurry.

[0060] Bentonite has extremely strong water absorption and expansion properties, and the fine particles of fly ash can fill the gaps between bentonite particles. The 3:1:2 ratio gives the plugging material both good fluidity and high sealing strength. The injection rate is controlled at 8-12 L / min because too fast a rate will cause uneven distribution of the material within the fractures, creating a channel effect that affects the sealing range; too slow a rate will result in low efficiency. The disappearance of the self-absorption phenomenon indicates that the plugging material has filled the main fractures, reducing the formation's grout absorption capacity. The 5-8 minute settling period allows the material to initially solidify, forming a stable primary sealing layer and preventing subsequent scouring by pure cement grout from causing plugging failure. The optimization improves the cost-effectiveness and sealing effect of the plugging material through precise ratio and rate control: the synergistic effect of bentonite and fly ash reduces material costs while achieving rapid sealing of large fractures; the settling period enhances the stability of the primary sealing layer, creating conditions for permanent reinforcement with pure cement grout, further improving the economy and reliability of the process.

[0061] Based on any of the above technical solutions, the following optimization is made: In step 3, when injecting cement grout under pressure, the pressure is less than or equal to 75%-80% of the safe bearing pressure of an open casing, and the pressure rise rate is controlled at 0.08-0.1MPa / min to avoid the casing from being ruptured by impact.

[0062] A safety margin is provided to ensure that the grout fully penetrates into micro-cracks under pressure, while preventing excessive pressure from causing plastic deformation or rupture of the casing. The pressure rise rate is controlled at 0.08-0.1 MPa / min because rapid pressure changes can generate instantaneous impact forces exceeding the casing's impact resistance, and may also cause grout to rapidly accumulate in cracks, forming blockages and affecting the diffusion range. Slow pressure increases allow the grout to penetrate at a uniform rate, gradually filling cracks and reducing the porosity of the grout-formed aggregate. The core function of this optimization is to achieve a balance between safety and effectiveness: setting an upper pressure limit avoids the risk of structural damage, while controlling the pressure rise rate ensures uniform grout diffusion and consolidation quality. Compared to uncontrolled pressurized grouting, this optimization significantly improves construction safety while ensuring a tight bond between the grout and the formation, enhancing the overall strength of the solidified casing structure.

[0063] Based on any of the above technical solutions, a further optimization is made in step 4: the water-cement ratio of the cement grout used for patching is 0.8-1.0, the grouting rate is 5-8 L / min, and the patching pressure is maintained at 0.3-0.4 MPa. This ensures that the annular space shrinkage gap is filled.

[0064] Grouting targets the tiny shrinkage cracks in the top annular space. A cement grout with a water-cement ratio of 0.8-1.0 combines good fluidity with high setting strength. Fluidity ensures the grout can penetrate the tiny cracks, forming a high-strength, solidified mass after setting. The grouting rate is 5-8 L / min, lower than the main grouting rate, because the grouting space is narrow, and excessive speed could cause a sudden pressure surge that could damage the superstructure. The grouting pressure is maintained at 0.3-0.4 MPa, which is higher than the capillary resistance of the shrinkage cracks to drive the grout filling, but lower than the main grouting pressure to avoid impacting the already solidified structure. Stable pressure ensures the grout fully fills the cracks without leaving any dead corners. This optimization achieves efficient filling of shrinkage cracks through precise material proportioning and parameter control: the water-cement ratio design solves the problem of difficult grouting of tiny cracks, and the rate and pressure control ensure the safety and density of the grouting process, ultimately ensuring the integrity of the solidified pipe structure and preventing groundwater from seeping through the cracks and corroding the casing later.

[0065] Based on any of the above technical solutions, the following optimization is made: In step 1, the second casing is lowered to a depth that meets the requirement that the bottom guide head is 2-3m away from the lower interface of the fractured stratum, and the casing lowering resistance is monitored by a pressure gauge during the lowering process. When the resistance exceeds 5kN, the lowering angle is adjusted.

[0066] The casing lowering depth is controlled at 2-3m from the guide head to the lower interface of the fractured formation. This depth allows the casing body to cover the fractured formation, while the guide head penetrates into the lower stable formation. The support of the stable formation enhances the overall stability of the casing, preventing subsequent formation deformation that could cause casing tilting. Lowering resistance is indirectly reflected by a pressure gauge: as resistance increases, the pressure gauge at the orifice changes due to friction between the casing and the borehole wall. A pressure exceeding 5kN indicates potential borehole wall collapse or rock debris accumulation. Adjusting the lowering angle changes the direction of force, reducing frictional resistance. This optimization ensures effective casing coverage of the fractured formation through precise depth control. Resistance monitoring and angle adjustment solve the problems of casing jamming and stuck during lowering in fractured formations, preventing forced lowering that could lead to casing deformation or borehole wall collapse. This improves the success rate and stability of casing installation, providing a reliable structural support for subsequent casing reinforcement processes.

[0067] Based on any of the above technical solutions, a further optimization is made: the matching pressure monitoring element records data every 3-5 minutes. If the pressure suddenly drops by more than 0.3 MPa, the grouting should be stopped immediately, and the sealing gasket of the grouting joint, the valve core of the high-pressure ball valve, and the pipeline interface should be checked. Grouting can only be resumed after the leak is eliminated.

[0068] Pressure is a core parameter in the grouting process. Recording pressure every 3-5 minutes allows for timely capture of pressure change trends, preventing the loss of abnormal signals due to excessively long recording intervals. A sudden pressure drop of more than 0.3 MPa indicates a significant leak in the system, where grout is leaking from the leak instead of flowing to the formation as expected. Continuing grouting at this point will lead to material waste and reduced consolidation effectiveness. Leaks often occur at dynamic seals or connections such as grouting joint gaskets, high-pressure ball valve cores, and pipe interfaces. These areas are prone to gaps due to improper installation or wear. This optimization enables rapid early warning of pressure anomalies through high-frequency monitoring. Stopping grouting for inspection allows for precise location and timely repair of leaks, preventing leaks from expanding and causing more serious construction problems. Compared to traditional periodic inspections, this optimization significantly improves leak detection efficiency, reduces grout waste, and ensures the continuity and consolidation quality of the grouting process.

[0069] Example 2: Compared with Example 1, this example also includes the following technical features: The present invention also provides a pipe-stabilizing device for implementing the above-mentioned pipe-stabilizing process in fractured formations, comprising a first open sleeve, a second open sleeve, a grouting joint, a high-pressure ball valve, an vent, a pressure monitoring element, an orifice device, and a guide head.

[0070] The first-layer casing serves as the outer load-bearing structure, providing the installation foundation and pressure bearing capacity. The second-layer casing, as the inner working casing, directly contacts the fractured strata, achieving precise casing fixation. The grouting joint and high-pressure ball valve form a controllable grout inlet channel, controlling the start and stop of grouting and material switching via valve operation. The vent hole, located above the grouting joint, follows the gas-liquid separation principle to remove air from the system. Pressure monitoring elements collect data in real time, providing a basis for pressure control. The orifice device integrates multiple functions, improving operational convenience and data reliability. The guide head solves the casing lowering and positioning problem. All components form an organic whole through structural design, adapting to the needs of phased grouting: from positioning and guidance during equipment installation, to pressure control and material switching during grouting, and then to subsequent grouting reinforcement, each part of the device precisely matches the process steps. The purpose of this device is to provide dedicated hardware support for the grouting process in fractured formations. By standardizing components and adapting functions, it reduces construction difficulty and improves the accuracy and safety of process implementation. Compared with general grouting devices, its targeted design solves core problems such as guidance, sealing, and pressure control in grouting in fractured formations, and is a key hardware foundation for ensuring the effectiveness of the process.

[0071] A grouting joint is welded to the outer wall of the open sleeve. A high-pressure ball valve is detachably installed on the grouting joint to form a grout inlet channel. An exhaust hole is opened on the outer wall of the open sleeve 30-50cm directly above the grouting joint. A high-pressure ball valve is installed on the exhaust hole to form an exhaust / back pressure channel. A pressure monitoring element is fixedly installed at the grout inlet channel near the grouting joint.

[0072] The grouting joint and high-pressure ball valve are detachably connected, facilitating installation and maintenance while allowing for quick shut-off of the grout inlet channel to handle emergencies. The vent is located 30-50cm directly above the grouting joint; this distance ensures grout enters from the bottom and air exits from the top, creating a smooth flow pattern and preventing air blockage. The high-pressure ball valve at the vent also functions as a vent and backpressure valve; when closed, it forms a closed system, working in conjunction with the grout inlet channel to transmit pressure. A pressure monitoring element located near the grouting joint directly collects the grout pressure entering the annular space, providing more accurate data and avoiding measurement errors caused by pipeline resistance. This structure, through the position and functional design of the inlet and outlet channels, ensures thorough gas-liquid separation during grouting, improving grout diffusion efficiency. The detachable valve and precise pressure monitoring enhance construction flexibility and safety; in case of abnormal pressure, the grout inlet can be quickly shut off for troubleshooting, providing reliable channel control and data support for high-pressure grouting.

[0073] The diameter of the double-sleeve is smaller than that of the single-sleeve. The bottom of the double-sleeve is fixedly connected to a guide head by a thread. The guide head is a conical alloy steel support and is filled with cement. A drainage hole with a diameter of 5-10mm is opened on it.

[0074] The diameter of the second-stage casing is smaller than that of the first-stage casing, forming an annular grouting space to provide a channel for grout filling and achieve consolidation of the casing, grout, and formation. The guide head is made of conical alloy steel. The conical structure utilizes the principle of force dispersion at the tip to reduce lowering resistance, while the alloy steel material enhances wear resistance and strength, making it suitable for complex environments in fractured formations. Cement filling inside increases the weight of the guide head, improving lowering stability and preventing deviation. A 5-10mm drainage hole drains slurry that enters the guide head during lowering, preventing internal slurry accumulation that could lead to uneven weight distribution or structural corrosion. Threaded connections facilitate the prefabrication, installation, and replacement of the guide head, improving construction efficiency. The function of this structure is to create a grouting space through pipe diameter design. The structural and material design of the guide head solves the problems of casing jamming and deviation in fractured formations. The drainage holes and threaded connections improve the durability and ease of construction of the device, ensuring the accurate and stable lowering of the second-stage casing to the target layer.

[0075] The orifice device is connected to the top of an open sleeve via a flange. The orifice device integrates an auxiliary pressure gauge and a shock-absorbing oil cup. The range of the auxiliary pressure gauge is not less than 1.2 times the safe bearing pressure of the open sleeve.

[0076] The structure of the orifice device can adopt existing technologies. When using flange connection, it has the characteristics of good sealing and convenient disassembly, ensuring a firm connection between the orifice device and the open sleeve, and avoiding leakage during high-pressure grouting. The auxiliary pressure gauge and the pressure monitoring element of the grout inlet channel form a dual monitoring system. The range is not less than 1.2 times the safe bearing pressure. The measurement principle of reserving a safety margin in the range is followed to avoid the pressure exceeding the range and causing instrument damage, thereby improving data reliability. The anti-wear hydraulic oil in the shock-absorbing buffer oil cup can absorb the pressure impact during grouting. Through the hydraulic buffer principle, the impact of pressure fluctuations on the pressure gauge is reduced, extending the service life of the instrument.

[0077] The structure ensures sealing safety through flange connections, improves data accuracy through dual pressure monitoring, and protects instruments from impact damage with shock-resistant buffer oil cups. The overall design solves the problems of inaccurate pressure monitoring and easy instrument damage during high-pressure grouting, providing reliable protection for pressure control and improving construction safety.

[0078] The annular space at the top of the first and second open sleeves is sealed by welding steel plates, and the weld height is not less than 1.5 times the sleeve wall thickness.

[0079] The top annular space is a critical area for grouting pressure transmission. Full welding of the steel plate creates a continuous sealing surface, preventing grout leakage from the top of the annular space. The weld height is no less than 1.5 times the casing wall thickness because the weld's load-bearing strength is positively correlated with its height. This height design ensures the weld strength is no less than the casing body strength, preventing cracking under pressure during high-pressure grouting. Continuous welding is used to avoid leakage channels formed by intermittent welds. The function of this structure is to ensure the sealing and load-bearing capacity of the annular space through high-strength welds, ensuring effective transmission of grouting pressure to formation fractures and preventing insufficient grout diffusion due to pressure leakage. Simultaneously, the weld strength matches the casing, enhancing the overall load-bearing capacity of the entire solidification structure and providing a safe and reliable sealed environment for high-pressure grouting.

[0080] Based on any of the above technical solutions, a further optimization is made as follows: the pressure monitoring element is an orifice wireless pressure gauge, which is connected to the slurry inlet pipeline by a threaded seal, and the seal is wrapped with polytetrafluoroethylene raw material tape to prevent slurry leakage from affecting pressure detection.

[0081] The wireless pressure gauge at the orifice eliminates the need for wired connections, preventing line damage caused by pipeline vibration during grouting. It also enables remote data transmission for real-time monitoring. The threaded sealing connection is simple in structure and provides excellent sealing. When used with PTFE (polytetrafluoroethylene) PTFE tape, the tape undergoes plastic deformation when the threads are tightened, filling the tiny gaps between the threads to form a reliable sealing layer and preventing grout leakage from the connection. Grout leakage can cause corrosion and damage to the pressure monitoring element, and the resulting pressure loss can distort the measurement data. This optimization enhances the convenience and anti-interference capabilities of monitoring through wireless design, preventing line faults from affecting data acquisition; the reinforced sealing design prevents grout leakage, protects the monitoring element from damage, and ensures the accuracy of pressure data. Compared to traditional wired pressure gauges and ordinary seals, this optimization significantly improves the stability and lifespan of pressure monitoring, providing more reliable data support for grouting pressure control.

[0082] Based on any of the above technical solutions, a further optimization is made as follows: the diameter of the vent hole is 1 / 2 to 2 / 3 of the inner diameter of the grouting joint, and the inner wall of the vent hole is galvanized for corrosion protection to prevent formation water from corroding the hole wall and causing the hole diameter to increase.

[0083] The vent hole diameter is designed to be 1 / 2 to 2 / 3 of the grouting joint's inner diameter because the required venting volume is less than the grouting volume. This ratio ensures smooth air discharge while preventing grout from overflowing too quickly and causing waste. If the hole diameter is too large, grout may overflow prematurely, affecting the grouting pressure buildup; if the hole diameter is too small, venting will be obstructed, creating air resistance. Formation water contains minerals and corrosive components. Long-term contact can lead to corrosion and thinning of the vent hole wall, increasing the hole diameter and affecting venting and backpressure functions. Galvanized anti-corrosion treatment forms a dense zinc protective layer on the hole wall, preventing corrosion through sacrificial anode protection. This optimization balances venting efficiency and grouting pressure buildup through precise hole diameter design; galvanized anti-corrosion treatment extends the service life of the vent hole, preventing functional failure due to corrosion, ensuring the stability and reliability of the venting / backpressure channel throughout the grouting process, and improving the long-term stability of the process.

[0084] Based on any of the above technical solutions, the following further optimizations are made: the bottom conical angle of the guide head is 30°-45°, the two ends of the drainage hole are rounded to prevent scraping the ground or clogging during lowering, and high-strength sealant is applied to the threaded connection between the guide head and the two-opening sleeve.

[0085] The guide head's conical angle is 30°-45°. This angle range reduces lowering resistance by distributing force at the tip while ensuring sufficient support area for the guide head body. This prevents excessive wear due to a small angle or increased resistance due to a large angle. The drainage holes are rounded at both ends to eliminate sharp edges, preventing them from scraping the hole wall and causing collapse during lowering. It also prevents rock debris from getting stuck and causing blockage, ensuring unobstructed drainage. High-strength sealant is applied to the threaded connections. The sealant's adhesive and filling properties fill the tiny gaps between the threads, preventing formation water from entering and corroding the threads, while also enhancing the threaded connection's strength. This optimization, through the angle and rounded design, improves the safety of the guide head's lowering, reducing damage to the hole wall and the risk of blockage. The sealant treatment enhances the sealing and strength of the connection, preventing the guide head from detaching due to corrosion during long-term use and ensuring the long-term stability of the casing.

[0086] Based on any of the above technical solutions, a further optimization is made: after the weld of the annular space at the top of the first and second sleeves is completed, a 0.5MPa water pressure test must be performed. If there is no leakage after 30 minutes of pressure holding, the orifice device can be installed to ensure the sealing performance of the annular space.

[0087] The top annular space weld is a critical sealing component of the closed system. A 0.5MPa hydrostatic test, lower than the main grouting pressure but higher than the formation hydrostatic pressure, effectively verifies the weld's sealing performance. Holding the pressure for 30 minutes allows sufficient time for water penetration. If the weld contains micropores or cracks, water will gradually penetrate, manifesting as a pressure drop or leakage. Only a leak-free pressure hold ensures no pressure leakage during subsequent high-pressure grouting, preventing grout waste and reduced consolidation due to weld leakage. This optimization precisely verifies the weld sealing quality through a specialized hydrostatic test, allowing for early detection and repair of weld defects. Compared to visual inspection alone, the hydrostatic test can detect minute, hidden defects, ensuring the annular space's sealing performance meets high-pressure grouting requirements. This provides core assurance for the pressure construction of the entire closed system, preventing construction failure due to weld issues.

[0088] Based on any of the above technical solutions, a further optimization is made: the top of the shock-absorbing buffer oil cup configured in the orifice device is provided with a vent hole, and a dust filter is installed at the vent hole to prevent dust from entering the oil cup and contaminating the anti-wear hydraulic oil, thus affecting the buffering effect.

[0089] The shock-absorbing buffer cup absorbs pressure shocks through its internal anti-wear hydraulic oil. A vent at the top of the cup balances the internal and external air pressure, preventing pressure buildup caused by oil temperature changes leading to oil volume expansion or contraction, which could affect the buffering effect. Without the vent, oil expansion could damage the cup, and contraction could create negative pressure, hindering buffering. A dust filter installed at the vent filters airborne dust and impurities, preventing them from entering the cup and contaminating the hydraulic oil. This prevents impurities from altering oil viscosity or clogging internal channels, ensuring stable buffering function. This optimization balances air pressure through the vent, guaranteeing the normal buffering function of the buffer cup; the dust filter prevents oil contamination, extending the cup's lifespan and ensuring stable buffering performance, protecting pressure monitoring instruments from long-term impact damage and improving the reliability of pressure monitoring.

[0090] Based on any of the above technical solutions, the following optimization is made: the welding parts of the grouting joint and the open sleeve are both made using double-sided welding process, and after welding, ultrasonic non-destructive testing is performed to ensure that there are no pores or cracks at the weld, making it suitable for high-pressure grouting conditions (pressure resistance not less than 10MPa).

[0091] Double-sided welding, by forming welds on both sides of the joint, significantly increases the strength of the welded area compared to single-sided welding. This effectively withstands the radial pressure during high-pressure grouting and prevents weld cracking. Ultrasonic non-destructive testing utilizes the varying propagation speeds of ultrasound in different media to detect hidden defects such as porosity and cracks within the weld. These defects are difficult to detect visually but severely affect the weld's pressure resistance. The design, with a pressure resistance of no less than 10 MPa, far exceeds the grouting pressure in the process, providing ample safety margin. This optimization enhances the weld's load-bearing strength through double-sided welding, while ultrasonic testing ensures the weld is free of internal defects. The combination of these two methods ensures that the connection between the grouting joint and the casing meets the strength and sealing requirements of high-pressure grouting. Compared to conventional welding and inspection, this optimization significantly improves the reliability of the connection, preventing grout leakage or structural damage due to weld failure during high-pressure grouting, thus providing core safety assurance for high-pressure grouting operations.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. For those skilled in the art, any alternative improvements or transformations made to the implementation of the present invention fall within the protection scope of the present invention.

[0093] Any aspects of this invention not described in detail are well-known to those skilled in the art.

Claims

1. A pipe penetrating process for breaking a ground formation, characterized by, It comprises the following steps: Step 1, equipment installation: drill a borehole, weld a grouting joint on the outer wall of the first casing, open an exhaust hole and assemble a first casing into the borehole; fix a guide head at the bottom of the second casing, pass the second casing into the first casing and lower it to the target layer of the broken formation; Seal the annular space at the top of the first casing and the second casing by full welding of the steel plate, and install an integrated pressure gauge and orifice device at the top of the first casing; Step 2, connect the matched grouting pump and grouting joint, and do water pressure test on the annular space of the second casing and the broken formation; open the high-pressure ball valve at the exhaust port at the top of the second casing and the exhaust hole of the first casing during the test; Step 3, observe the exhaust port fluid, if the exhaust port at the top of the second casing is self-sucking, first inject the plugging material through the grouting joint; if the exhaust hole of the first casing is liquid, close the high-pressure ball valve and inject pure cement slurry; after the pure cement slurry overflows from the valve port at the top of the first casing, press 1 / 2 volume of clean water into the casing to wash and close the valve, and continue to inject the cement slurry under pressure; Step 4, monitor the pressure, and stop injecting when the pressure naturally returns to zero; Mix the cement slurry manually to supplement the grout in the annular space at the top of the two casings, and complete the casing fixation when the supplementing pressure is stable for 30 minutes.

2. A process for fracturing a subterranean formation as defined by claim 1, wherein: In step 2, the water pressure test pressure is controlled at 0.2-0.5 MPa by the matched pressure monitoring element for 15-20 minutes, and if the water outflow from the exhaust ports of the two casings is uneven, check whether the casing sealing part leaks.

3. A process for fracturing a subterranean formation as defined by claim 2, wherein: In step 3, the plugging material is made of bentonite, fly ash and water in a mass ratio of 3:1:2, the injection rate is controlled at 8-12 L / min, and after the self-sucking phenomenon disappears, the pure cement slurry is injected after standing for 5-8 minutes.

4. A process for fracturing a subterranean formation as defined by claim 3, wherein: In step 3, when the cement slurry is injected under pressure, the pressure is less than or equal to 75%-80% of the safe bearing pressure of the first casing, and the pressure rise rate is controlled at 0.08-0.1 MPa / min to avoid casing rupture caused by impact.

5. A process for fracturing a subterranean formation as defined in claim 4 wherein: In step 4, the water-cement ratio of the grouting cement slurry is 0.8-1.0, the grouting rate is 5-8 L / min, and the grouting pressure is maintained at 0.3-0.4 MPa to ensure that the annular space shrinkage gap is filled.

6. A process for fracturing a subterranean formation as defined by claim 5, wherein: In step 1, the depth of the second casing lowering meets the requirement that the distance between the guide head at the bottom and the lower interface of the broken formation is 2-3 m, and the casing lowering resistance is monitored by the pressure gauge during the lowering process. If the resistance exceeds 5 kN, the lowering angle is adjusted.

7. A process for fracturing a subterranean formation as defined by claim 6, wherein: The matched pressure monitoring element records data every 3-5 minutes, and if the pressure drops by more than 0.3 MPa, the injection is stopped immediately, the sealing gasket of the grouting joint, the valve core of the high-pressure ball valve and the pipeline interface are checked, and the leakage point is eliminated before grouting.

8. A process for fracturing a subterranean formation as defined by claim 6, wherein: A casing fixation device is used in the broken formation casing fixation process, which comprises a first casing, a second casing, a grouting joint, a high-pressure ball valve, an exhaust hole, a pressure monitoring element, an orifice device and a guide head; The grouting joint is welded on the outer wall of the first casing, the high-pressure ball valve is detachably installed on the grouting joint to form a grouting channel, the exhaust hole is opened on the outer wall of the first casing 30-50 cm above the grouting joint, the high-pressure ball valve is installed on the exhaust hole to form an exhaust / counter-pressure channel, and the pressure monitoring element is fixedly installed on the grouting pipeline close to the grouting joint; The diameter of the two-opening sleeve is smaller than that of the one-opening sleeve, and a guide head is fixedly connected to the bottom of the two-opening sleeve through threads, the guide head is a conical alloy steel support filled with cement inside, and a drainage hole with a diameter of 5-10 mm is formed on the guide head; The orifice device is connected to the top end of the one-opening sleeve through a flange, and an auxiliary pressure gauge and an anti-shock buffer oil cup are integrated on the orifice device, wherein the range of the auxiliary pressure gauge is not less than 1.2 times the safe bearing pressure of the one-opening sleeve; The top annular space of the one-opening sleeve and the two-opening sleeve is sealed through steel plate welding, and the height of the welding seam is not less than 1.5 times the sleeve wall thickness.

9. A process for fracturing a subterranean formation as defined by claim 8, wherein: The pressure monitoring element is an orifice wireless pressure gauge, the orifice wireless pressure gauge is threadedly and sealingly connected to the slurry inlet pipeline, and a polytetrafluoroethylene raw material belt is wound around the sealing part to prevent slurry leakage from affecting pressure detection.

10. A process for fracturing a subterranean formation as defined by claim 9, wherein: The diameter of the exhaust hole is 1 / 2-2 / 3 of the inner diameter of the grouting joint, and the inner wall of the exhaust hole is subjected to galvanizing anticorrosion treatment.

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