Seismic exploration explosive package plugging method, formula, tool and process

Abstract

The invention discloses a seismic exploration explosive package plugging method, which comprises the following steps: based on an energy conversion mechanism excited by seismic exploration explosives, injecting a plugging agent into an excitation well by using a tool, plastically plugging a gap between an explosive package and surrounding rock, rigidly plugging a channel of a shaft at the top of the explosive package, and improving the excitation energy and frequency band of seismic waves. The method for filling the plugging agent comprises but is not limited to a one-way valve filling barrel filling method, a plug filling barrel filling method, a funnel filling pipe filling method, a slurry pump filling pipe filling method and a method for directly filling the plugging agent from a wellhead. The method comprises but is not limited to a combined plugging method adopting plastic plugging and rigid plugging, a rigid plugging method singly adopted and a plastic plugging method singly adopted. The method comprises but not limited to a method for completely plugging a gap between an explosive charge and a surrounding rock and a shaft channel at the top of the explosive charge, and a method for partially plugging the shaft channel at the top of the explosive charge.

Description

Technical Field

[0001] The present invention belongs to the technical fields of seismic exploration data acquisition technology and blasting operation technology, and particularly relates to a method, a formula, tools and a process for plugging seismic exploration explosive packages. Background Technique

[0002] China's seismic exploration technology originated in the 1950s and has since become the main exploration method for discovering large oil and gas fields in China. Through the efforts of several generations, the BGP of CNPC has now become the largest geophysical company in the world, with its business covering the globe.

[0003] The most primitive excitation technology for seismic exploration is the explosive source. A shallow borehole (dozens of meters deep) is drilled on the surface, the explosive package and the electric detonator are lowered into the well, and the detonator cable is led to the surface. A remote-controlled exploder is used to detonate the electric detonator and the explosive to generate a pulsed seismic wave. With the development of society, the controlled source excitation technology emerged in the 1970s for exciting seismic waves on the surface where vehicles can pass; however, the explosive source is still the main excitation source for seismic exploration, especially in exploration areas where vehicle access is difficult, such as mountains, loess plateaus, large deserts, farmlands, swamps, etc., and it is an irreplaceable excitation method.

[0004] The mechanism of the explosive source for exciting seismic waves is that at the moment of explosive explosion, the explosive gasifies to generate high-temperature and high-pressure gas, and the instant high pressure of the gas pushes the surrounding rock to vibrate to generate seismic waves. The efficiency of the conversion of explosive energy into seismic wave energy is related to the structure of the wellbore, the lithology of the surrounding rock, and the depth of the phreatic surface. Generally, in the plain area, it is better to select the clay formation below the phreatic surface for excitation, and the excitation well depth and charge amount are determined through experiments. However, the lithology of the surrounding rock and the phreatic surface exist naturally and cannot be changed. For example, the excitation lithology in mountains and loess plateaus is determined and there is no water in the excitation well. After determining the excitation well depth and charge amount through experiments, the only excitation condition that can be changed manually is to change the structure of the wellbore to improve the excitation effect. Through years of field practice, engineers have a profound understanding of the structure of the excitation wellbore: when the well is drilled, the explosive is lowered, and the well is not filled for excitation, the explosive explosion gas flow rushes out of the wellhead, causing energy leakage and polluting the surface, with small excitation energy, narrow frequency band, and poor excitation effect; when the well is drilled, the explosive is lowered, and the well is filled for excitation, the excitation effect is good; but the excitation quality depends on the filling effect of the well. Therefore, the seismic exploration data acquisition technology community has carried out long-term and unremitting exploration and research on the well filling (plugging) technology.

[0005] Existing explosive plugging methods and problems at present:

[0006] 1. Drilling debris well filling method

[0007] After drilling the excitation well and setting the explosive, backfill the formation debris generated during drilling from the wellhead into the well with a shovel to achieve the effect of well killing. This method is the mainstream or even the only plugging method in current seismic exploration and has the following characteristics: In plain areas, it is effective in exploration areas with a sandy-muddy structure near the surface and a relatively shallow water table. The plugging effect is related to the excitation lithology. The plugging effect for excitation in clay layers is good, while that in sand layers is poor. The plugging effect is related to the water table. The plugging effect for excitation below the water table is good, while that above the water table is poor. The plugging effect is related to the backfilled debris. The backfilling effect of sand, mud, and hard clay debris is good, while that of pure sand is poor. The plugging effect is related to the precipitation and cementation time of the debris after backfilling. The longer the time, the better the effect. The plugging effect is related to the well depth. Due to the irregular wellbore structure, if the well is too deep, it is difficult for the backfilled sand and mud debris to fall to the position of the explosive package. The plugging effect is related to the responsibility of the operator. The drilling debris backfilling method is a technological process that cannot be quantitatively quality controlled. In mountainous areas, loess plateaus and other water-deficient near-surface exploration areas, plugging is ineffective. The main reason is that after backfilling the drilling cuttings, since there is no water in the well, precipitation cementation cannot form and it cannot integrate with the surrounding rock, failing to achieve the plugging effect. Instead, when firing the shot, the high-pressure air flow will wash the backfilled sand and gravel into the sky, causing a huge safety hazard.

[0008] 2. Wooden plug hammering method

[0009] In swamp exploration areas, since the excitation well is about 6 meters shallow, the charge is less than 1 kg, the excitation lithology is good (clay), the data quality is good, and there is rich forest resources at the edge of the swamp. After the explosive is excited, sulfide and carbonized gases are ejected from the wellhead with water, polluting the swamp water system and causing the death of surface animals and plants. The geophysical prospecting team uses locally available materials to make wooden plugs that are basically the same diameter as the wellbore from newly cut trees, and uses a sledgehammer + drill pipe to hammer the wooden plugs into the well for plugging. There are the following problems: In terms of the method, the well depth cannot be too deep as the depth of the wooden plug hammered in is limited. In terms of resources, there should be large forests nearby. In terms of environmental protection, cutting down forests damages the environment, which is a way of using evil to control evil. In terms of the effect, there is no major problem just after firing the shot, but the gas generated after the explosive explodes has been trapped in the well. The interface between the wooden plug and the wellbore wall is the weak point of this balance system. Over time, the air flow seeps into the surface along the wooden plug surface and gradually pushes out part of the wooden plug from the wellbore, and the pollution of the surface water system has not been completely cured.

[0010] According to relevant information, some domestic seismic teams use a plugging method with cylindrical bricks plus an outer wrapping of an expanding agent. Its basic principle is to make cylindrical bricks with a diameter equivalent to that of the explosive as the matrix, wrap the expanding agent around the cylindrical bricks and lower them into the well to the top of the explosive package. After the expanding agent encounters water and expands, it plugs the well. The plugging effect is unknown. However, from the perspective of the method, industrialization cannot be achieved either, because the three major technical problems of tight coupling, solidification, and compaction among the brick, the expanding agent, and the wellbore wall cannot be solved, and the cost and labor intensity are not discussed here.

[0011] It should be noted that the plastic anti-explosive buoyancy device used in seismic exploration is installed on the top of the explosive package. In wells with a shallow water table, it is a device to prevent the explosive package from floating due to buoyancy and does not have the function of plugging.

[0012] 3. Method of pouring sand, gravel and cement slurry

[0013] The inventor was engaged in the research of small-dose cement plugging projects. The method was to pour sand, gravel and cement slurry into the well at the wellhead for plugging after drilling the well and setting the charge. Since it was uncertain whether the pouring was in place during the pouring process, the only quality control method was to fill the wellbore with sand, gravel and cement slurry up to the wellhead. The data quality was greatly improved compared with the method of filling the well with drilling cuttings and was much better than not filling the well. However, the project was not promoted and had the following problems: At that time, seismic exploration was mainly in the stage of structural exploration in the plain area. The exploration community generally believed that as long as the reflected energy was sufficient, the method of filling the well with drilling cuttings also had good effects. This method required a large amount of cement, sand, gravel and water supply, increasing exploration costs such as materials and transportation. Mainly because the transport vehicles of seismic teams were very tense at that time. The labor intensity of the operation was large, increasing labor costs. Ground mixing and pouring into the well from the wellhead caused cement consolidation pollution to the farmland near the wellhead.

[0014] 4. Method of plugging with formed plugging agent

[0015] In the 2010s, the inventor cooperated with a research institution to conduct research on the method of plugging with explosive plugging agent and developed a formed plugging agent. The basic method was to make the plugging agent into the same shape and specification as the explosive, connect it to the top of the explosive and lower it into the well with the explosive. The plugging agent undergoes physical and chemical reactions when it encounters water, first expands and then solidifies, and finally completely plugs the wellbore at the top of the explosive. The test data had good effects, but it was not promoted either and had the following problems: The expansion force was too large (10 - 30 MPa), breaking some of the running lines. The comprehensive costs such as material cost, manufacturing cost, packaging cost, moisture-proof cost and transportation cost reached an unacceptable level of the seismic exploration acquisition cost.

[0016] In recent years, with the progress of exploration and development technologies, oil and gas field development has extended to low-signal-to-noise areas of seismic exploration in mountainous areas and loess plateaus, and to weak reflection energy strata of seismic exploration in deeper reservoirs (more than 8,000 meters). Higher requirements have been put forward for the excitation energy and frequency band of seismic exploration. Since the seismic exploration acquisition technology has achieved a very high coverage rate, the space for greatly improving the quality of seismic results is very limited. It has urgent practical significance to revive the technology of plugging explosive packages in seismic exploration. However, due to environmental protection requirements, the raw materials of explosive plugging agents are not easily obtained. After a large amount of research, it was decided to use an alternative method to develop a formed plugging agent. However, the results were disappointing after different formula tests. Either the expansion coefficient was not enough or the solidification force after expansion was not enough. The research and development of the formed plugging agent was in an embarrassing situation.

[0017] 5. Inspiration from Mud Sealing in Mine Blasting

[0018] The mud sealing technology for mine (coal mine) blasting refers to using mud to seal the borehole opening after charging the drill hole, which can improve the blasting effect and prevent the explosion gas from overflowing. The composition of mud for different working conditions is very complex. The main component of general mud is fine clay. The clay and water are kneaded evenly by a mud machine (dough mixer) to a hardness similar to that of hard rubber clay, and then extruded into cylindrical mud according to the borehole diameter. A wooden stick is used to push the cylindrical mud into the borehole for sealing. The sealing length is not less than 0.3 meters, and the sealing length of deep boreholes is not less than 1 / 3 of the length of the explosive package. Clay mud has the characteristics of high temperature resistance, expansibility, adhesiveness and cementation. The mud sealing technology for mine blasting has become a standard technology for mine blasting, providing a research idea that can be used for reference for the in-depth study of the mud sealing technology for seismic exploration explosive packages.

[0019] To sum up, none of the above sealing methods can fundamentally solve the industrial application problem of seismic exploration explosive package sealing. They all end up halfway, and currently, the most primitive method of filling the well with drilling cuttings is still used. Summary of the Invention

[0020] The purpose of the present invention is to solve the above problems and provide a seismic exploration explosive package sealing method, formula, tool and process with simple method, ordinary materials, simple operation and low cost.

[0021] To solve the above technical problems, the technical solution of the present invention is: a seismic exploration explosive package sealing method, including a method for improving the seismic wave excitation energy and frequency band by using tools to pour a sealing agent into the excitation well based on the energy conversion mechanism of seismic exploration explosive excitation, plastically sealing the gap between the explosive package and the surrounding rock, and rigidly sealing the channel of the wellbore at the top of the explosive package.

[0022] Further, the method for pouring the sealing agent includes but is not limited to various methods for pouring the sealing agent into the excitation well, including the one-way valve pouring bucket pouring method, the plug pouring bucket pouring method, the funnel plus pouring pipe pouring method, the mud pump plus pouring pipe pouring method, and the direct pouring method from the wellhead, etc.

[0023] Further, the method includes but is not limited to the combined sealing method of plastic sealing plus rigid sealing, the single rigid sealing method and the single plastic sealing method.

[0024] Further, the method includes but is not limited to the method of completely sealing the gap between the explosive package and the surrounding rock and the channel of the wellbore at the top of the explosive package, or the method of partially sealing the channel of the wellbore at the top of the explosive package.

[0025] The present invention also provides a formula for a plugging agent for seismic exploration explosive packages, characterized in that it includes a plastic plugging agent formula and a rigid plugging agent formula. The plastic plugging agent formula includes, but is not limited to, various mixtures having the elastic properties of water and the plastic properties of fine powder, wherein the mixtures include various clays, bentonite, kaolin, clay powder, fine soil, fine-grained powdered cuttings of seismic drilling, etc. in the category of fine powder; drilling mud, clay, and water.

[0026] Furthermore, the formula of the rigid plugging agent includes, but is not limited to, various mixtures having micro-expansion properties and consolidation and compaction properties. The mixtures include cement, expansive agents such as calcined calcium oxide, sand or coarse-grained gravel cuttings of seismic drilling, and water.

[0027] The present invention also provides a plugging tool for seismic exploration explosive packages, including, but not limited to, tools for stirring and pouring the plugging agent into the well. The tools include: a stirring tank, stirring shovels, a plug head pouring bucket, a one-way valve pouring bucket, a funnel, a mud pump, and a pouring pipe. The mixture is put into the stirring tank and mixed with the stirring shovels. The stirred mixture is used through the above different tools in combination with different working conditions; the one-way valve pouring bucket and the plug head pouring bucket are suitable for all working conditions, and the combination of the funnel and the pouring pipe is suitable for shallow well working conditions with a depth less than 6 meters, and the combination of the mud pump and the pouring pipe is suitable for mud pump drilling working conditions.

[0028] The present invention also provides a plugging process for seismic exploration explosive packages, including the following steps:

[0029] S1. Before the well is completed and the explosive is placed, use the plugging tool to pour the plastic plugging agent into the bottom of the well;

[0030] S2. Lower the explosive package with an anti-floating device to the bottom of the well, and submerge the plastic plugging agent to the top of the explosive package;

[0031] S3. After the explosive is placed, use the plugging tool to pour the rigid plugging agent into the top of the explosive package, and the length of the rigid plugging agent blocking the wellbore channel is not less than 50 cm.

[0032] The beneficial effects of the present invention are:

[0033] 1. The plugging method, formula, tool, and process for seismic exploration explosive packages provided by the present invention achieve a comprehensive plugging of seismic exploration explosive packages with practical methods, ordinary materials, simple tools, and easy-to-operate processes, and explore a feasible technical route for improving seismic wave excitation energy and excitation frequency band research.

[0034] 2. The present invention is simple and easy to understand, safe to operate, and convenient for industrial promotion, providing inclusive technical support for the general improvement of the quality of seismic exploration explosive excitation data.

[0035] 3. The application cost of the present invention is quite low. Description of the Drawings

[0036] Figure 1 It is a schematic structural diagram of the one-way valve filling barrel of the present invention;

[0037] Figure 2 It is a schematic structural diagram of the plug filling barrel of the present invention.

[0038] Explanation of reference numerals: A, the first rope; B, the second rope; C, cotton ball; D, one-way valve; E, plug. Specific embodiments

[0039] The following further describes the present invention in conjunction with the accompanying drawings and specific embodiments:

[0040] As Figure 1 and Figure 2 shown, the seismic exploration explosive package plugging method provided by the present invention includes a method of improving the seismic wave excitation energy and frequency band by using tools to pour plugging agents into the excitation well based on the energy conversion mechanism of seismic exploration explosive excitation, plastically plugging the gap between the explosive package and the surrounding rock, and rigidly plugging the channel of the wellbore at the top of the explosive package.

[0041] In this embodiment, the energy conversion mechanism based on seismic exploration explosive excitation is the explosion mechanism excited by the explosive source. Theoretical and practical research on the explosive explosion mechanism shows that after the explosive explodes, the fracture zone, plastic zone, and elastic zone are three regions that describe the impact of the explosion on the surrounding medium (such as rock). The formation and characteristics of these regions are as follows:

[0042] A) Fracture zone: The fracture zone is the area directly affected by the explosion of the explosive and is located at the innermost part of the explosion point. In this area, the rock is directly impacted by the shock wave of the high-pressure gas generated by the explosion, resulting in the destruction of the rock structure, forming explosion cavities, rock fractures, and rock fragments. The diameter of the fracture zone depends on the compressive strength of the rock.

[0043] B) Plastic zone: The plastic zone is located outside the fracture zone. In this area, the stress on the rock exceeds its yield strength but does not reach the level of complete fragmentation. The rock undergoes irreversible deformation within the plastic zone but still maintains a certain degree of integrity. The diameter of the plastic zone depends on the yield strength of the rock.

[0044] C) Elastic zone: The elastic zone is located outside the plastic zone. In this area, the stress on the rock does not exceed its elastic limit, so the rock undergoes reversible elastic deformation. When the stress generated by the explosion disappears, the rock can return to its original shape.

[0045] The formation of the fracture zone, plastic zone, and elastic zone is related to factors such as the power of the explosive and the properties of the rock. The interface between the plastic zone and the elastic zone is the power source for generating seismic waves.

[0046] Experimental studies on the mechanism of explosive explosion show that the energy of elastic waves generated after the explosion of unconfined explosives is proportional to the diameter of the explosive charge. The spherical explosive charge has the best excitation effect. The total energy of elastic waves generated by the excitation of a cylindrical explosive charge is about 1.4 times the energy of elastic waves generated by the explosive contained in the length equal to the bottom diameter of the explosive charge. That is to say, the larger the diameter of the explosive charge, the greater the energy of the excited elastic waves. However, in practical applications, the length / diameter ratio of the explosive charge is greater than 10 and much larger than 1.4 times. After the explosive charge is detonated, the function of the upper part of the explosive charge is to exert a downward compaction effect formed by the superposition of explosion impact forces, and to increase the radius of the broken zone and plastic zone. Further research shows that the initial energy of seismic waves generated by the excitation of explosives, that is, the initial energy at the interface between the plastic zone and the elastic zone, only accounts for 2%-6% of the total energy of explosive excitation, and the work done on the broken zone and plastic zone consumes most of the energy of explosive excitation.

[0047] The reason why the explosive charge used in seismic exploration must be plugged is that the inventor conducted a comparative test of explosive excitation in the field. The excitation well depth was 18 meters and the charge amount was 0.5 kg. The surface was sealed with clay, the lithology in the well for excitation was hard clay, and the phreatic surface was 12 meters; Comparison: no filling in the 18-meter well, filling and plugging the 18-meter well with clay, filling the 18-meter well with sediment and cement slurry up to the wellhead for plugging, a 0.5-meter deep hole shot on the ground, a 0.1-meter deep hole shot on the ground plus a 26-ton vibration source flat plate pressing the explosive charge in the middle, and pre-vibrating the vibration source once to compact the explosive charge. The data quality was ranked from good to bad as follows: excellent: filling the 18-meter well with sediment and cement slurry up to the wellhead, filling the 18-meter well with clay; good: a 0.1-meter deep hole shot on the ground plus a 26-ton vibration source flat plate pressing the explosive charge in the middle, no filling in the 18-meter well; poor: a 0.5-meter deep hole shot on the ground. The main conclusion was obtained: whether the top of the explosive charge is plugged and compacted is the most important factor affecting the quality of seismic data.

[0048] The reason why the phreatic surface has such a great influence on the excitation effect is as follows:

[0049] A) Theoretical and practical data show that water is an excellent medium for the excitation and propagation of seismic waves by air-blast sources (explosives, air guns). Water has a high elastic modulus of 2.2 GPa, 0 shear modulus, infinite compressive strength, and infinite yield strength; the characteristics of small elastic deformation and no plastic deformation of water result in no broken zone and no plastic zone after the explosion of explosives in water, and the explosion energy is only consumed in the expansion and contraction of the explosive gas, with a large original amplitude and high original frequency of seismic waves; this is the main reason why marine seismic data is much better than land seismic data.

[0050] B) Excitation is carried out below the water table. The energy of the explosive explosion undergoes an evolution process through the high-pressure gas in the explosive package - the water (or mud) between the explosive package and the wellbore wall - the water-bearing solid surrounding rock, from gaseous energy - to liquid energy - to solid energy transfer process; through the role of the middleman water, water decomposes and shares the huge wave impedance difference between the gaseous state and the direct action on the solid state of the explosion energy, effectively reducing the energy consumption of the shock wave for impact fragmentation of the solid surrounding rock; enabling the shock wave pressure to be reduced in two steps, and the saved energy is converted into the broadening of the shock wave pulse time (frequency reduction), and finally applied to the water-bearing solid surrounding rock, reducing the radius of the broken zone, expanding and extrapolating the radius of the plastic zone, and increasing the seismic wave energy.

[0051] C) Excitation is carried out in the water-deficient and diagenetic old formation. The high-pressure gas energy of the explosive explosion is directly applied to the solid surrounding rock. Due to the huge wave impedance difference between the gas and the solid, the peak pressure of the shock wave (20 GPa pressure, 40 kHz frequency level) directly acts on the rock, and the shock wave energy greater than the rock fracture pressure (about 20 MPa) is consumed here to generate a broken zone, and the shock wave pressure is reduced by 1000 times. The yield strength of the diagenetic rock is about 10 MPa level, and the shock wave pressure above this pressure is consumed by the broken zone and the plastic zone. This consumption does not play a major role in broadening the shock wave pulse width, mainly a total energy consumption. Therefore, the 10 MPa yield strength determines that when excited in the diagenetic old formation, the original seismic wave has the characteristics of small amplitude and high frequency.

[0052] D) Excitation is carried out in the water-deficient and unconsolidated new formation. Due to the low elastic modulus (10 MPa level), low elastic deformation, very low compressive strength (kPa level), very low yield strength, and the characteristic of no elastic property of water to support the bottom of the water-free sandy soil layer, the high-pressure gas energy of the explosive explosion is directly applied to the unconsolidated surrounding rock similar to fine glass fiber cementation without diagenesis, resulting in a large-scale collapse cavity of the surrounding rock after the explosion, and it is difficult for the explosion energy to be converted into seismic wave energy. The original seismic wave has the characteristics of very small amplitude and high frequency.

[0053] The main conclusions are obtained: When excited below the water table, the explosive explosion energy undergoes a three-state conversion and transfer process from gaseous - to liquid - to solid, with good excitation effects. When excited in the water-free formation, the explosive explosion energy undergoes a two-state conversion from gaseous - directly acting on solid, with very poor excitation effects. Whether it is possible to build a bridge for three-state conversion in the wellbore and improve the excitation effect has become the core technical issue in the research of excitation structures.

[0054] The reason why the formed plugging agent must have a large expansion coefficient is as follows: Since the formed plugging agent needs to be lowered to the top of the explosive package, the diameter of the plugging agent cannot be too large. It can only be made to a size equivalent to the diameter of the explosive package to be lowered into the well. After the plugging agent swells upon contact with water, it must expand to be tightly coupled with the wellbore. After the plugging agent solidifies, it can become integrated with the formation. After the explosive detonates, the plugged section does not break, shift, or leak air, achieving the effect of plugging and compaction. According to the actual gap between the explosive package and the wellbore, it is required that the volume expansion coefficient of the plugging agent is greater than 2.

[0055] Main conclusion: Solving the core technical problems of smoothly lowering the plugging agent into the well and densely filling the space between the plugging agent and the wellbore for the plugging of the explosive package.

[0056] The methods adopted by the present invention for pouring the plugging agent include, but are not limited to, various methods of pouring the plugging agent into the excitation well, including the one-way valve pouring bucket pouring method, the plug head pouring bucket pouring method, the funnel plus pouring pipe pouring method, the mud pump plus pouring pipe pouring method, and the direct pouring method from the wellhead.

[0057] The methods of the present invention include, but are not limited to, the combined plugging method of using plastic plugging plus rigid plugging, the separate use of the rigid plugging method, and the separate use of the plastic plugging method.

[0058] The methods of the present invention include, but are not limited to, the method of fully plugging the gap between the explosive package and the surrounding rock and the wellbore passage at the top of the explosive package, as well as the method of partially plugging the wellbore passage at the top of the explosive package.

[0059] The present invention also discloses a formula for the plugging agent of the seismic exploration explosive package, including the plastic plugging agent formula and the rigid plugging agent formula. The formula of the plastic plugging agent includes, but is not limited to, various mixtures with the elastic properties of water and the plastic properties of fine powder. The mixtures include various clays, bentonites, kaolinites, clay powder, fine soil in the category of fine powder, fine-grained powdered rock cuttings from seismic drilling; drilling mud, clay; and water.

[0060] After being stirred with water, the plastic plugging agent forms a paste-like non-Newtonian fluid, which has the properties of high viscosity, high expansibility, and low water loss. When stressed, it shows the elastic characteristics of water, and after being stressed, it shows the plastic deformation characteristics of fine powder.

[0061] The formula of the rigid plugging agent includes, but is not limited to, various mixtures with micro-expansion properties and consolidation and compaction properties. The mixtures include cement, expansion agents such as calcined calcium oxide, sand or coarse-grained sandstone cuttings from seismic drilling, and water.

[0062] After being stirred with water, the rigid plugging agent forms a sand-cement slurry with a density of about 3 g / cm³, which has the semi-flowing properties of a non-Newtonian fluid after stirring; after being poured into the well, it quickly fills up to the wellbore, and after standing, it has the characteristics of micro-expansion, cementing with the wellbore surrounding rock, and quickly solidifying into one body with consolidation and compaction characteristics.

[0063] The present invention also discloses a plugging tool for seismic exploration explosive packages, including but not limited to tools for stirring and pouring plugging agents into wells. The tools include: a stirring tank, stirring shovels, a plug filling bucket, a check valve filling bucket, a funnel, a mud pump, and a pouring pipe. The mixture is placed in the stirring tank and mixed with the stirring shovels. The stirred mixture is used through the above different tools according to different working conditions. The check valve filling bucket and the plug filling bucket are suitable for all working conditions. The combination of the funnel and the pouring pipe is suitable for shallow well working conditions with a depth less than 6 meters. The combination of the mud pump and the pouring pipe is suitable for mud pump drilling working conditions.

[0064] In this embodiment, the stirring tank: a rectangular basin-shaped container for stirring the plugging agent and water, and the size is designed according to the working conditions. The long side of the rectangular stirring tank is in a 90-degree upright shape, and the short side is in a 45-degree slope shape for easy stirring by the stirring shovel. An arched slope opening baffle is welded to the top of one end to close the slope, and a cylinder with a diameter of 5 cm is welded above the slope, which is convenient for pouring out the plugging agent from the container after stirring.

[0065] The check valve filling bucket, as Figure 1 shown. The diameter of the steel pipe is equivalent to the diameter of the explosive, and the wall thickness is 2 - 3 mm. The length is designed according to the working conditions. A circular hinge check valve D is connected to the bottom of the steel pipe; inside the check valve D, away from the hinge direction, at the midpoint of the hinge radius, a first rope A longer than the well depth is connected. The first rope A passes through the steel pipe, and a sponge mass or a cloth mass is fixed 20 cm from the rope outlet of the bucket. In this embodiment, a cotton mass C is used to wipe lubricating oil or washing powder water on the inner wall of the filling bucket. The first rope A plays a role in closing the check valve D and bearing and pulling during the process of filling the plugging agent and lowering it into the well. A second rope B longer than the well depth is connected to the top of the steel pipe. The second rope B is lifted upward to open the check valve D, pour the plugging agent into the well, and lift the steel pipe filling bucket out of the well.

[0066] The plug filling bucket, as Figure 2 shown. The diameter of the steel pipe is equivalent to the diameter of the explosive, and the wall thickness is 2 - 3 mm. The length is designed according to the working conditions. The difference between the plug filling bucket and the check valve filling bucket is that the bottom of the steel pipe is finely processed to maintain the section accuracy. The plug E is a circular steel cake plug with a thickness of 10 mm. The outer diameter of the circular cake plug is equal to the outer diameter of the steel pipe, the first inner diameter is equal to the inner diameter of the steel pipe minus 1 mm, the bottom thickness from the outer diameter to the first inner diameter is 4 mm, and the wall thickness of the right-angle plug plate is 3 mm. The first inner diameter forms an outer cone shape with an angle of 60 degrees towards the center, which is convenient for the bottom of the steel pipe to sit into the right-angle plug plate during operation; a first rope A longer than the well depth is connected to the center point of the plug. The first rope A passes through the steel pipe, and a sponge mass or a cloth mass is fixed 20 cm from the rope outlet of the bucket. In this embodiment, a cotton mass C is used to wipe lubricating oil or washing powder water on the inner wall of the filling bucket. A second rope B longer than the well depth is connected to the top of the steel pipe.

[0067] The combination of the funnel and the filling pipe is suitable for shallow well conditions with a depth less than 6 meters. Among them, the funnel with a diameter of 10 cm is connected to the filling pipe with a diameter of 5 cm and a length of 6 meters.

[0068] The combination of the mud pump and the filling pipe is suitable for the mud pump drilling condition, where the length is determined according to the well depth, and the filling pipe with a diameter of 5 cm is connected to the output end of the mud pump.

[0069] For the proportioning of the plugging agent, sand, and water under different near-surface conditions, refer to the proportioning of concrete for building pouring. In this embodiment, taking the steel pipe filling bucket (check valve, plug) as an example, calculate the amount of plugging agent according to the diameter of the explosive package and the actual diameter of the wellbore, and determine the length of the steel pipe filling bucket, customize the steel pipe filling bucket and the mixing tool.

[0070] Estimating with a bit diameter of 7 cm, an actual well diameter of 8 cm, and an explosive package diameter of 6 cm, and the inner diameter of the steel pipe filling bucket of 6 cm: For an explosive package with a diameter of 6 cm, the length of a 1 kg explosive package is about 30 cm. If the excitation charge is 4 kg, the total length of the explosive package is about 120 cm. The gap volume between the explosive and the wellbore wall is 3.14*(4*4 - 3*3)*120 = 2637.6 cubic centimeters; the minimum length of the plastic plugging agent required in the steel pipe filling bucket is 2638 / 3.14 / (3*3)≈93.34 cm = 0.9334 m. The length of the rigid plugging agent used to plug the wellbore is 50 cm, and the minimum length of the rigid plugging agent required in the steel pipe filling bucket is 3.14*(4*4)*50 / (3.14*(3*3))≈88.88 cm = 0.8888 m. Therefore, this condition requires customizing the length of the steel pipe filling bucket to be about 1 m; the total weight of a 1 m long steel pipe filling bucket filled with rigid plugging agent is about: 3.14*100*(3*3*3+(3.2*3.2 - 3*3)*7.85)=11534.476 g≈11.5 kg, where the weight of the rigid plugging agent is about 8.5 kg and the weight of the steel pipe filling bucket is about 3 kg.

[0071] The present invention also discloses a seismic exploration explosive package plugging process, including the following steps:

[0072] S1. Before well completion and explosive charging, use a plugging tool to pour the plastic plugging agent into the bottom of the well.

[0073] Step S1 further includes the following sub-steps:

[0074] S11. Before well completion and explosive charging, dip the sponge mass C of the steel pipe filling bucket in lubricating oil or washing powder water, pull the first rope A from the bottom of the filling bucket, and wipe the inner wall of the steel pipe filling bucket with the sponge mass C dipped in lubricating oil or washing powder water to reduce the adhesion of the plastic plugging agent to the inner wall of the filling bucket.

[0075] S12. Stir the plastic plugging agent and water evenly in a mixing box to form a paste-like state.

[0076] S13. Place the steel pipe filling bucket on the ground, close the one-way valve D or the plug E, tighten the first rope A upward. At this time, the second rope B is in a free state. Under the action of the self-weight of the steel pipe filling bucket, the one-way valve D or the plug E and the bottom of the steel pipe are in a closed state, and pour the plastic plugging agent into the steel pipe filling bucket.

[0077] S14. Use the first rope A as a traction to lower the steel pipe filling bucket to the bottom of the well; keep the second rope B in a free state during the process of lowering into the well.

[0078] S15. Loosen the first rope A and slowly lift the second rope B. Under the pressure of the self-weight of the plastic plugging agent, the one-way valve D or the plug E will open automatically, and the plastic plugging agent will flow from the filling bucket into the bottom of the well. Due to the low water loss of the plastic plugging agent (the strong surface tension property of fine powder particles), the plastic plugging agent in the well is in a thick milk state with non-Newtonian fluid properties for a quite long time.

[0079] S16. Lift the steel pipe filling bucket out of the wellbore.

[0080] S2. Lower the explosive package with an anti-floating device to the bottom of the well, and submerge the plastic plugging agent to the top of the explosive package.

[0081] In this step, under the action of the anti-floating device, the explosive package will not float.

[0082] S3. After putting the explosive, use a plugging tool to pour the rigid plugging agent into the top of the explosive package. The length of the rigid plugging agent blocking the wellbore channel is not less than 50 cm.

[0083] Step S3 also includes the following sub-steps:

[0084] S31. Stir the rigid plugging agent, sand and water evenly in the mixing tank.

[0085] S32. Place the steel pipe filling bucket on the ground, close the one-way valve D or the plug E, tighten the first rope A upward. At this time, the second rope B is in a free state. Under the action of the self-weight of the steel pipe filling bucket, the one-way valve D or the plug E and the bottom of the steel pipe are in a closed state, and pour the rigid plugging agent into the steel pipe filling bucket. Since the specific gravity of the steel pipe is greater than that of the plugging agent, as long as the load-bearing is all on the first rope A, there will be no phenomenon of the plugging agent leaking from the bottom.

[0086] S33. Use the first rope A as a traction to lower the filling bucket to the anti-floating device on the top of the explosive package. Keep the second rope B in a free state during the process of lowering into the well. When checking the lowering depth marked on the rope and feeling that there is no tension on the first rope A, it means that the filling bucket has seated on the anti-floating device.

[0087] S34. Loosen the first rope A, slowly lift the second rope B. Under the pressure of the self-weight of the rigid plugging agent, the one-way valve D or the plug E will open automatically, and the rigid plugging agent will flow out of the filling barrel. Under the action of the semi-fluid property of the plugging agent, a section of the wellbore above the anti-floating device will be filled and compacted with the rigid plugging agent. Lift the second rope B. If the pulling force suddenly becomes smaller, it indicates that all the rigid plugging agent has been poured into the wellbore. Lift the second rope B by another 1 meter, then lower the filling barrel. When there is no pulling force on the second rope B, check the depth marked on the rope, which is the height of the ash surface where the rigid plugging agent seals the wellbore.

[0088] S35. Lift the steel pipe filling barrel out of the wellbore.

[0089] S36. Part of the cement and water mixture of the rigid plugging agent seeps into the surrounding rock, and the plugging agent gradually expands slightly and solidifies, consolidating with the surrounding rock as a whole.

[0090] Finally, the plugging work of the explosive package is completed.

[0091] Compared with the existing dilatant non-Newtonian fluid hole sealing, in the prior art, a kind of stemming used in mine blasting is adopted, and there are essential differences between the stemming sealing in mines and the present invention:

[0092] 1) The application business fields are different. The stemming is applied to mine exploitation, while the present invention is applied to seismic exploration.

[0093] 2) The explosives to be plugged are different. Small-dose bulk gunpowder is used in mines, while large-dose shaped high-explosives are used in the present invention.

[0094] 3) The effects are different. In mine plugging, it is required to generate the largest fracture zone and the smallest elastic wave energy after explosion, while in the plugging of the present invention, it is required to generate the smallest fracture zone and the largest elastic wave energy.

[0095] 4) The plugging positions are different. In mines, only the outlet of the blast hole is plugged, while in the present invention, the periphery of the explosive package is plugged in all directions.

[0096] 5) The formulations of the non-Newtonian fluids are different. The formulation of the mine stemming is made into a cylindrical shaped solid, and the plugging agent becomes liquid after explosion; the plugging of the present invention is made into a thin paste-like bulk fluid, and the plugging agent becomes solid after explosion.

[0097] 6) The plugging processes are different. In mine plugging, the method of stuffing with a wooden stick is used, while in the plugging of the present invention, the method of pouring with a filling barrel is used.

[0098] In the prior art solutions, gun clay is used to block the outlet of the blast hole. Since the blasting charge in the mine is small and the blasting power is low, the gun clay can block the blast hole. However, for seismic exploration blasting with a large blasting power, it is very difficult to block the shaft with plastic plugging agent gun clay. Therefore, only cement slurry solidification plugging can be used. In the present invention, the plastic plugging agent is blocked between the explosive package and the surrounding rock and reaches the top of the explosive package. The function is that the high-pressure gas generated by the explosion of the explosive does not directly act on the rock. The plastic plugging agent acts as a buffer second-hand, reducing the pressure of the high-pressure gas, broadening the gas pulse width and reducing the frequency, minimizing the energy loss of the high-pressure energy to the fracture zone, converting its energy into a lower frequency band, and increasing the elastic wave energy.

[0099] Those of ordinary skill in the art will realize that the embodiments described herein are for helping the reader understand the principles of the present invention, and it should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those of ordinary skill in the art can make various other specific deformations and combinations without departing from the essence of the present invention based on the technical revelations disclosed in the present invention, and these deformations and combinations are still within the protection scope of the present invention.

Claims

1. Method for plugging seismic exploration explosive package, characterized in that: A method for improving seismic wave excitation energy and frequency band, which includes the energy conversion mechanism based on the excitation of seismic exploration explosives, uses tools to pour plugging agents into the excitation well, plastically plugs the gap between the explosive package and the surrounding rock, and rigidly plugs the channel of the wellbore at the top of the explosive package.

2. The seismic exploration explosive package plugging method according to claim 1, characterized in that: The methods for pouring the plugging agent include, but are not limited to, various methods of pouring the plugging agent into the excitation well, including the one-way valve pouring bucket method, the plug head pouring bucket method, the funnel plus pouring pipe method, the mud pump plus pouring pipe method, and the direct pouring method from the wellhead, etc.

3. The method for plugging an explosive package for seismic exploration according to claim 1, characterized in that, The method includes, but is not limited to, the combined plugging method of plastic plugging plus rigid plugging, the separate use of the rigid plugging method and the separate use of the plastic plugging method.

4. The seismic exploration explosive package plugging method according to claim 1, characterized in that, The method includes, but is not limited to, the method of completely plugging the gap between the explosive package and the surrounding rock and the channel of the wellbore at the top of the explosive package, or the method of partially plugging the channel of the wellbore at the top of the explosive package.

5. The formula of the plugging agent for seismic exploration explosive packages, characterized in that: It includes the plastic plugging agent formula and the rigid plugging agent formula. The plastic plugging agent formula is various mixtures with the elastic properties of water and the plastic properties of fine powder, including, but not limited to, various clays, bentonites, kaolinites, clay powder, fine soil, fine-grained powdered rock cuttings from seismic drilling, etc. in the category of fine powder; seismic drilling mud, clay, and water.

6. The formula of the plugging agent for seismic exploration explosive package according to claim 5, characterized in that: The rigid plugging agent formula is various mixtures with micro-expansion properties and consolidation and compaction properties, including, but not limited to, cement, expansion agents such as calcined calcium oxide; sand or coarse-grained rock cuttings from seismic drilling; water.

7. Seismic exploration explosive package plugging tool, characterized in that, The plugging tools are various tools with the function of stirring and pouring the plugging agent into the well, including, but not limited to, mixing tanks, mixing shovels, plug head pouring buckets, one-way valve pouring buckets, funnels, mud pumps, pouring pipes, etc. The mixture is put into the mixing tank and mixed with a mixing shovel. The mixed mixture is used through the above different tools according to different working conditions; the one-way valve pouring bucket and the plug head pouring bucket are suitable for all working conditions, and the combination of the funnel and the pouring pipe is suitable for the shallow well working condition with a depth less than 6 meters, and the combination of the mud pump and the pouring pipe is suitable for the mud pump drilling working condition.

8. The plugging process of seismic exploration explosive package is characterized in that, It includes the following steps: S1. Before the well is completed and the explosive is placed, use the plugging tool to pour the plastic plugging agent into the bottom of the well; S2. Lower the explosive package with an anti-floating device to the bottom of the well, and submerge the plastic plugging agent to the top of the explosive package; S3. After placing the explosive, use the plugging tool to pour the rigid plugging agent into the top of the explosive package, and the length of the rigid plugging agent plugging the wellbore channel is not less than 50 cm.

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