Method for plugging leakage and gushing in small-caliber core drilling by using expansive fiber cement paste

Abstract

The invention provides a method for plugging leakage and gushing in small-caliber core drilling by using expansive fiber cement paste, and belongs to the technical field of geological drilling. Early-strength adjustable cement (hereinafter referred to as early-strength cement), water and a leakage plugging agent containing a ductile fiber material are adopted as a leakage plugging mixture; for a micro-leakage stratum and a small-leakage stratum, pumping water to press the leaking stoppage mixture into the leakage hole section; in a medium-large-leakage and completely water-return-free stratum, the primarily poured mixture is mainly pasty, the addition amount of an extension fiber material and the use amount of cement are increased or decreased, or a material which has flexibility and can expand when encountering water is added, and pumping water is started to press the leaking stoppage mixture into a leakage hole section; in a water gushing stratum, a box is opened to pressurize a water head, and a pump is started to convey water to press the leaking stoppage mixture into a leakage hole section; if a large water gushing stratum is encountered, weighted slurry is pumped for pressure; the invention mainly aims at the problems of water leakage and water gushing in small-caliber core drilling engineering, especially the problem of leakage and water gushing drilling easily encountered in a shallow hole section or a complex stratum.

Description

TECHNICAL FIELD

[0001] The application provides a method for plugging leakage and gushing of small-diameter core drilling by using expansive fiber cement slurry, and belongs to the technical field of engineering geological drilling. BACKGROUND

[0002] Small-diameter core drilling for prospecting is constantly shifting the focus from the surface and shallow part to the deep part and concealed ore body, and deep hole drilling has become a common geological exploration means. Small-diameter drilling is widely used in the field of infrastructure construction, and investment in this field is increasing. For example, new iron under extremely complex geological conditions needs to check the geological conditions along the line. How to smoothly pass through the shallow hole section and complex strata during the exploration stage has become a prerequisite for the drilling target to be crossed. Leakage or water gushing is easily encountered in the shallow hole section or complex strata, which is the most common engineering problem in the implementation process of these major projects, challenging technical personnel, and it is very difficult to solve this problem in practice. According to hydrogeology, groundwater is divided into aeration zone water, phreatic water and confined water according to the burial conditions of water, and is divided into void water, fissure water and karst water according to the nature of the water layer. From the perspective of drilling, aeration zone water will not have a great impact on drilling and is basically under the isolation control of the casing. The flow direction of phreatic water, the hydraulic slope of phreatic water, the recharge-discharge relationship between phreatic water and river water, etc. will all have an impact on drilling. When the flow direction of phreatic water is significant and the hydraulic slope is large, it may cause drilling leakage or water gushing. Due to different topographic conditions, water permeability of aquifer, runoff conditions, etc., especially when the runoff conditions are good, the hydraulic slope is large, and the confined water head is large, when drilling encounters water storage layers, large leakage or large water gushing may occur. Complex strata and geological structures have undergone complex tectonic movements, and tectonic traces are widely developed, forming many long and wide fracture zones with well-developed fissures. In fissured strata, there is seasonal water storage in the upper part, and in the fracture zone of syncline or monoclinal structure, the confined water layer has large water volume and high water head. These are the main hydrogeological reasons for encountering leakage or water gushing during drilling. In engineering construction, the situation of no water return from the stratum has a serious impact on drilling. Because the mud is completely lost, the drill pipe loses effective lubrication of the drilling fluid, causing the hole load to increase sharply, the drilling machine cannot work normally, and even the drill pipe is twisted off, causing accidents. Once the stratum borehole loses the effective support of the mud, borehole collapse is likely to occur, leading to drill sticking, drill burying and other serious accidents. If complex strata with developed underground water are encountered, water gushing is likely to occur, and the water gushing volume is too large when the drill is lifted, and the water gushing pressure is large, which also affects normal production and construction, and even causes the phenomenon that the inner tube cannot be put into operation, forcing the drilling to stop. At present, there are mainly two methods to solve the leakage and water gushing of the stratum: The first method is pure cement slurry plugging, Cement slurry plugging is one of the most common methods used in drilling construction site, and the gradual plugging is followed in the process of plugging. The amount of mud is gradually increased by using the plugging method. In the process of plugging, sawdust, horse manure and other inert materials are continuously added. When groundwater is developed or the water power gradient of the stratum is large, it is often useless, and the groundwater flow channel cannot be well blocked, so it is difficult to achieve the ideal effect. In the tectonic trace widely developed, the fracture and fracture zone formed is long, and the fissure is very developed. The cement slurry is easy to lose in the high permeability stratum. When the groundwater layer or confined water layer with good runoff condition is encountered, the cement slurry is easy to be carried away by the underground runoff, resulting in plugging failure. Even if the amount of cement slurry is increased, it is also useless. The amount of cement slurry is only a drop in the ocean compared with the huge underground runoff. When the water gushing stratum is drilled, the confined water layer is often entered. At this time, it is more difficult to plug with the traditional simple cement slurry. The reason is very simple. Because the cement slurry has strong fluidity, it cannot form effective pressure control when meeting the underground water gushing, resulting in the dispersion and dilution failure of the cement slurry itself. The root cause of the failure of plugging and gushing is that the water flow channel is not effectively blocked and intercepted. Second, the conventional plugging of ordinary inert materials, For micro-loss stratum or small-loss stratum, the amount of plant glue in the flushing fluid can be increased, or the while-drilling plugging king is added to plug The ordinary inert small particle material plugging can achieve good effect on micro-loss stratum and small-loss stratum, but it is difficult to achieve effect on medium-loss, large-loss and water gushing stratum. For large-loss, completely no-return water or large water gushing stratum, the plugging king + barite powder method needs to be used for comprehensive plugging. However, the method is complex and difficult to master, and the time for cleaning the materials in the hole is long. When the groundwater layer or confined water layer with good runoff condition is encountered, it is difficult to block the water flow channel. SUMMARY

[0003] In view of the above technical problems, the present application provides a method for plugging and gushing of small-diameter core drilling by using expandable fiber cement slurry, to solve the following technical problems: The purpose is to solve the problem that when the deep hole engineering drilling of geological prospecting deep concealed ore body encounters large loss and large water gushing stratum, a more reasonable treatment method is formed by using natural law, trying, innovating and discovering new technology, new material and new mechanism, so that the hole section part is smoothly and quickly passed, the deep drilling is entered, and the high-quality, efficient and low-cost drilling target is achieved. Objective two: The geological exploration drilling encountered extremely complex and diverse geological conditions. The geological characteristics of the route were high intensity, well-developed bedding fractures, and no water return throughout the entire borehole section. The goal was to solve the formation leakage problem by plugging leaks, thus paving the way for the use of fault-based mud suppression, altering the physicochemical environment within the borehole, forming a new mud circulation system, and creating conditions for successful drilling. The specific technical solution is as follows: The method of plugging leaks and seepage in small-diameter core drilling using expansive fiber cement grout is divided into the following three types based on the leakage or seepage situation: Scenario 1: Micro-loss formations, small-loss formations Early-strength cement, water, and a leak-stopping compound containing ductile fibers are used. The above materials are thoroughly mixed and stirred. The mixture is quickly poured into the hole, and the pump is turned on to push the leak-stopping mixture into the leaking section. The pump is then turned off, and the mixture is left to stand until the cement mixture in the leaking section solidifies. The machine is then started to drill. Scenario 2: Medium to large leakage, no water return formation Early-strength cement, water, and a leak-stopping compound containing ductile fiber are used. The above materials are thoroughly mixed and stirred. The initial mixture is mainly in paste form. The amount of ductile fiber material and cement added is adjusted according to the actual size of the leak on site. Alternatively, a flexible material that can expand when exposed to water is added. The mixture is quickly poured into the hole, and water is pumped to force the leak-stopping mixture into the leaking section. The pump is then turned off, and the mixture is allowed to stand until it solidifies. The machine is then started to drill. Scenario 3: Water-bearing strata To plug leaks and stop seepage in a water-bearing formation, the first step is to open the tank and pressurize the water head. (1) If a small water inflow formation is encountered, paste-like barite powder is thrown into the borehole to increase the density of the fluid in the borehole until the water inflow is controlled and a space is formed in the surface drill rod or drill sleeve. Early-strength cement, water and a plugging agent containing ductile fiber material are used to fully mix and stir the above materials. The initial mixture is mainly in paste form. The amount of ductile fiber material and cement is increased or decreased according to the actual leakage on site. The mixed mixture is quickly poured into the borehole. The pump is turned on to send water to press the plugging mixture into the leakage section. The pump is turned off and left to stand until the cement mixture is completely solidified in the leakage channel before the drilling machine is turned on. (2) If a large water inflow formation is encountered, pump weighted mud to press the borehole, and then plug the leak according to the method in (1) above. Furthermore, in scenario one, add 50-100 kg of early-strength cement to water (water-cement ratio 0.6-0.8), and then add 0.05-0.2 kg of a sealant containing ductile fiber material. In scenario two, use 50-300 kg of early-strength cement, add water (water-cement ratio 0.45-0.6), and then add 1-3 kg of a sealant containing ductile fiber material. The material with flexibility and water-expanding function can be partially made of local dry branches or fallen leaves, In case three, 50-300 kg of early strength cement, water, water-cement mass ratio of 0.45-0.6, and 1-3 kg of the plugging king containing ductile fiber material are added, The plugging and gushing method and principle provided by the application mainly aims at the water leakage and gushing problem of small-diameter core drilling engineering, especially the leakage and gushing drilling problem easily encountered in the shallow hole section or complex stratum. The scheme has certain originality in the technical method, problem analysis and mechanism of plugging and gushing, and has achieved good practical effect in field engineering test, BRIEF DESCRIPTION OF DRAWINGS

[0004] Figure 1 Schematic diagram of cement three components and fiber action; Figure 2 Schematic diagram of simple cement slurry plugging; Figure 3 Schematic diagram of cement slurry plugging with oil expansion fiber; Figure 4 One of the core photos of the leakage stratum of the embodiment; Figure 5 Two of the core photos of the leakage stratum of the embodiment; Figure 6 Three of the plugging effect photos of the leakage stratum of the embodiment; Figure 7 Four of the plugging effect photos of the leakage stratum of the embodiment, DETAILED DESCRIPTION

[0005] The specific technical scheme of the application is described in combination with the embodiment, The formula, operation and applicable conditions of the scheme of the application are as follows: In case one, the micro-leakage stratum and small-leakage stratum, 50-100 kg of early strength cement, water, water-cement mass ratio of 0.6-0.8, and 0.05-0.2 kg of the plugging king containing ductile fiber material are added, and the above materials are fully mixed and stirred; the plugging mixture is quickly poured from the hole, water is pumped to press the plugging mixture into the leakage hole section, the pump is closed, and the mixture is left for 4-6 hours (the cement mixture in the leakage section has been solidified), and the machine is started for drilling, Scenario 2: For medium to large leakage in formations with no backflow (drilling), use 50-300 kg of early-strength cement, add water (water-cement ratio 0.45-0.6), and 1-3 kg of a plugging agent containing extensible fiber material. Thoroughly mix the above materials. Initially, the mixture should be a paste. Adjust the amount of extensible fiber material and cement according to the actual leakage on site. A small amount of locally sourced dead branches and leaves can also be added; choose branches and leaves with good flexibility and some expansion when wet. Quickly pour the mixture into the borehole, start the pump to force the plugging mixture into the leakage section, turn off the pump, let it stand for 4-8 hours, and then start drilling. Case 3: Water-bearing formation. In water-bearing formations, the first step in plugging and sealing is to open the box and pressurize the water head (pressurize the water); (1) If a small water-bearing formation is encountered, it is necessary to throw a paste-like barite powder into the borehole to increase the density of the fluid in the borehole until the water inflow is controlled, and a space is formed in the surface drill (sleeve) rod. Use 50-300 kg of early-strength cement, add water, with a water-cement mass ratio of 0.45-0.6, and 1-3 kg of plugging agent containing ductile fiber material. Mix the above materials thoroughly and stir evenly; initially pour the mixture into a paste-like form, and then... Adjust the amount of extended fiber material and cement according to the actual leakage size on site. Quickly pour the mixed mixture into the hole, turn on the pump to send water to press the plugging mixture into the leakage hole section, turn off the pump and let it stand for 12-24 hours until the cement mixture is completely solidified in the leakage channel, then turn on the drilling machine. (2) If a large water inflow formation is encountered, throw paste barite powder at the hole opening. If it is difficult to suppress the water inflow head, it is necessary to pump weighted mud to press the hole, and then perform the above (1) method to plug the leak. The plugging method, materials and operation are the same. This invention utilizes the principle of the combined action of active and inactive leak-sealing materials: Small-diameter core drilling operations require rapid passage through complex lost-strength formations, necessitating selective plugging materials with requirements for rapid hardening, high early strength, and adjustable setting time. Research and engineering practice have demonstrated that early-strength cement is suitable. Its active material, anhydrous calcium sulfoaluminate clinker, primarily consists of anhydrous calcium sulfoaluminate and dicalcium silicate (mainly β-type), along with small amounts of calcium sulfate, perovskite, and iron-containing phases. These components, combined with most non-reactive fibrous materials, work synergistically to achieve the aforementioned objectives.

[0006] The hydration reaction between anhydrous calcium sulfoaluminate clinker and gypsum mainly takes the following two forms: 3CaO·3AL2O3·CaSO4+2(CaSO4·2H2O)+aq→ 3CaO·AL2O3·3CaSO4·31H2O+4AL(OH)3 (1) Formula 3CaO·3AL2O3·CaSO4+aq→ 3CaO·AL2O3·CaSO4·12H2O+4AL(OH)3 (2) From equation (1), it can be seen that when the molar ratio of gypsum to anhydrous calcium sulfoaluminate is equal to 2, all anhydrous calcium sulfoaluminate forms ettringite. If the molar ratio is less than 2, the amount of gypsum is insufficient, and some anhydrous calcium sulfoaluminate will react according to equation (2) to form monosulfide-type hydrated calcium sulfoaluminate. Therefore, reducing the amount of gypsum and reacting to obtain ettringite allows for the formation of a strong framework in a shorter time. On the other hand, the Ca(OH) precipitated during β-C2S hydration, under the condition of the presence of aluminum glue and gypsum, generates ettringite. 3Ca(OH)2+ 3(CaO·2H2O) +A1(OH)3+ aq→3CaO·AL2O3·3CaSO4·31H2O The hydration reaction of β-C2S accelerates the formation of hydrated calcium silicate gel, resulting in rapid densification of the cement stone structure and achieving early strength. The rate of early strength can be controlled by adjusting the gypsum content in the early-strength cement. The bonding medium is a non-reactive, expansive fibrous material that remains inert during the hardening process of the cement stone. After the cement stone forms, it acts as a skeletal framework, strengthening the tensile, compressive, and shear strength of the cement stone, creating a unique effect in the leak-sealing process, such as... Figure 1 The diagram shows the interaction between the three components of cement and fibers.

[0007] Mechanism of Leakage Sealing in Engineering Geological Construction: Using fiber-reinforced cement grout does not affect the conventional properties of cement grout and has the dual function of sealing leaks and gushing. It also significantly improves the toughness of cement stone, enhances the bonding quality at the interface, and ensures the integrity of the cement stone. The leak-sealing agent contains water-swellable fibers. When mixed with cement grout and injected into the hole, the fiber material does not affect the performance of the cement grout, thus providing the dual function of sealing leaks and gushing. Furthermore, it helps improve the toughness of the cement stone, enhances the bonding quality between cement and other materials, and ensures that the hardening effect of the cement stone is not affected. This effectively seals leaks and gushing. The leak-stopping compound contains a water-swelling fiber (with delayed-release properties). When the leak-stopping compound is mixed with cement slurry in a certain proportion, and the mixture is homogeneous, it can be pumped if the flow is within pumpable limits. If pumping is not possible, orifice injection is required. Once this expansive fiber cement slurry enters the orifice, the expansive fibers first expand upon contact with water, forming a network structure. This network forms the basic framework within the leakage or seepage channels. Coarse cement slurry particles begin to block the flow as they pass through the fiber "bridges" of the network structure. The leakage or seepage channels gradually become smaller and narrower until they are completely blocked. At this point, the cement slurry gradually enters its initial setting state, and its fluidity decreases significantly. The water, cement slurry, and leak-stopping fibers within the channels essentially become stagnant, creating conditions for cement to solidify. The successful solidification and blocking of the leak or seepage channels by the cement slurry within them signifies successful leak sealing. Figure 2 See the diagram for a simple cement grout sealing method. Figure 3 A schematic diagram of cement grout sealing with added expansive fibers.

[0008] Example 1: Field test of integrated exploration drilling for vanadium-titanium magnetite deposits in Panzhihua: 1. The arduous process of traditional leak sealing and slugging techniques During the leak-sealing process at borehole ZK11003 in the Hongge Vanadium-Titanium Magnetite Mine Area of ​​Panzhihua, a national integrated mineral exploration project, a gradual leak-sealing method was followed. Traditional cement slurry was used, with the amount of slurry gradually increased. Later, inert materials such as sawdust and donkey dung were added, but all to no avail. A total of nine leak-sealing attempts were performed without success. This failure directly led to the drying up of the reservoir's water source, making further drilling impossible and forcing a halt to the project. During the drilling of borehole ZK9803 in the same mining area, the traditional cement slurry plugging method was consistently used. On one occasion, five cement slurry plugging attempts were made in a single day, consuming a total of 2 tons of cement, but all were unsuccessful. This led to subsequent drilling losses and water inrush when the drill string was pulled, resulting in the serious consequences of the drilling unit being shut down and unable to carry out normal construction operations. 2. Successful application of the method of this invention (1) For ZK11001 drilling, first calculate the specific gravity of the weighted cement slurry to determine the amount of barite powder to add. After obtaining the amount of weighted cement slurry needed, pump it into the hole to create a pressure difference. Therefore, a pressure difference is formed at the top of the borehole. Then, mix water, sealant, and barite powder until it is semi-dry and semi-wet, and pour it directly into the hole. Start the pump to pump water to force the sealant mixture into the bottom of the hole. At this time, the pump pressure will rise. Maintain the pump pressure for a certain period of time. After the pump pressure gradually returns to normal, start drilling. Using this method, the leak was successfully sealed in one go, and the effect was very good. (2) After drilling ZK9803 to 80 meters, severe water inflow occurred in the formation, with a flow rate of 15 m3 / h and a water head pressure of 0.4 MPa. After numerous failed attempts to plug the inflow with traditional simple cement slurry, expansive fiber cement slurry was finally chosen for plugging. The preparation method is as follows: (4 bags of cement + water) Mixed evenly at a water-cement mass ratio of 0.5, then 20 kg of barite powder and 5 kg of plugging agent were added and mixed until semi-dry and semi-wet. The mixture was poured directly into the borehole, gradually suppressing the water inflow. The pump was turned on to pump water to push the plugging mixture into the bottom of the borehole. The pump pressure was maintained at 1.5 MPa for 8 hours. The borehole was then cleared, and no water inflow was found. The drilling was not leaking, indicating that the plugging was very successful. Engineering construction practice shows that expansive fiber cement slurry can play a very good role in plugging and sealing inflow. Core photos of lost strata at the site, such as Figure 4 and Figure 5 As shown in the photos, the effect of plugging the lost formation is as follows: Figure 6 and Figure 7 As shown, Example 2: Drilling and Construction Test along the Sichuan-Tibet Highway The geological features along the newly constructed Sichuan-Tibet Railway route are characterized by high intensity, high geothermal activity, high stress, and a strong development of diverse geological hazards and active faults. Bedding fissures are well-developed. During construction, drilling encountered Quaternary alluvial and diluvial deposits, primarily composed of fine, gravelly soils, and colluvial deposits at the foot of mountain slopes, consisting of gravelly soils, gravel, pebbly soils, and glacial till. These geological conditions posed significant challenges to drilling, primarily due to: fractured strata, water leakage, complete lack of water return in the borehole, ineffective mud systems, and difficulty in forming new physicochemical environments within the borehole. A particularly difficult problem encountered during construction was the encounter with a fault where water return was completely absent, and the use of specially formulated fault mud proved ineffective. The primary issue in addressing this problem is plugging the leaks. Repeated practice has proven that the application and selection of drilling mud are fundamental for handling deep boreholes in complex formations. Borehole plugging is a prerequisite for selecting and configuring fault-inhibiting mud. Dealing with muddy fault sections requires configuring fault-inhibiting mud to solve the problem of seepage of flushing fluid and its filtrate. This method is essential for navigating faults. To meet the physicochemical environment requirements within the borehole, a mud circulation system is needed, necessitating borehole plugging. When the method provided by this invention is tested, the delayed-expansion fiber material and cement slurry are mixed and injected into the hole to form a skeleton structure in the leakage channel. At the beginning, when the coarse particles of cement slurry pass through the mesh structure, the fluidity decreases and they gradually enter the initial setting state. The water in the channel basically enters a static state, which creates conditions for cement to solidify and effectively solves the problem of borehole leakage and backflow prevention. This creates the preconditions for preparing the anti-drilling mud, promotes the smooth progress of the Sichuan-Tibet line project exploration, and enables the project to achieve good economic and social benefits.

Claims

1. A method for plugging leakage and gushing in small-diameter core drilling by using an expansive fiber cement slurry, characterized in that, According to the leakage or gushing water, the following three cases are divided to deal with: Case one: micro-leakage formation, small leakage formation Early strength cement, water and plugging king containing ductile fiber material are fully mixed and stirred, and then the mixture is poured into the hole quickly, and the plugging mixture is pressed into the leakage hole section by pumping water, the pump is closed, and the cement mixture is solidified in the leakage section. Drilling is started; Case two: medium-large leakage, completely no return water formation Early strength cement, water and plugging king containing ductile fiber material are fully mixed and stirred, and then the mixture is poured into the hole quickly, and the plugging mixture is pressed into the leakage hole section by pumping water, the pump is closed, and the cement mixture is solidified in the leakage section. Drilling is started; Case three: gushing water formation In the gushing water formation, the water head is first pressed in the box: (1) If small gushing water formation is encountered, paste-like barite powder is thrown into the hole to increase the density of the fluid in the hole, until the gushing water is controlled, and a space is formed in the surface pipe or drill sleeve. Early strength cement, water and plugging king containing ductile fiber material are fully mixed and stirred, and then the mixture is poured into the hole quickly, and the plugging mixture is pressed into the leakage hole section by pumping water, the pump is closed, and the cement mixture is solidified in the leakage channel. Drilling is started again; (2) If large gushing water formation is encountered, pumping weighted mud is used to press the hole, and then the method of (1) is used to plug the hole.

2. The method for plugging leakage and gushing of small-diameter core drilling by using the expanded fiber cement slurry according to claim 1, characterized in that, In case one, 50-100 kg of early strength cement, water, water-cement mass ratio 0.6-0.8, and 0.05-0.2 kg of plugging king containing ductile fiber material are added.

3. The method for plugging leakage and gushing of small-diameter core drilling by using the expanded fiber cement slurry according to claim 1, characterized in that, In case two, 50-300 kg of early strength cement, water, water-cement mass ratio 0.45-0.6, and 1-3 kg of plugging king containing ductile fiber material are added.

4. The method for plugging leakage and gushing of small-diameter core drilling by using the expanded fiber cement slurry according to claim 1, characterized in that, The material with flexibility and water expansion is dry branches or fallen leaves.

5. The method for plugging leakage and gushing of small-diameter core drilling by using the expanded fiber cement slurry according to claim 1, characterized in that, In case three, 50-300 kg of early strength cement, water, water-cement mass ratio 0.45-0.6, and 1-3 kg of plugging king containing ductile fiber material are added.

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