Geological exploration bifurcated hole sealing device and method

Abstract

The invention provides a hole sealing device and method for a geological exploration bifurcated hole, and belongs to the technical field of hole packers.The hole sealing device for the geological exploration bifurcated hole comprises a pipe body, one end of the pipe body is provided with an opening, the other end of the pipe body is sealed, the pipe body comprises a grouting pipe, a centralizer, an ejector and a packing pipe which are communicated, and a plurality of nozzles are evenly arranged in the annular direction of the ejector and are detachable; the grouting pipe comprises an outer sleeve, a circulating hole is formed in the outer sleeve, and a slidable lower sliding sleeve and a closing sleeve are arranged in the outer sleeve. The problems existing in the prior art are solved, one-time well entering segmented splitting and full-well-section hole sealing or local hole sealing are achieved, and the problem that a large-depth ground exploration hole bifurcated hole is difficult to seal is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of hole sealers, and in particular relates to a device and method for sealing a bifurcated hole in geological exploration. Background Art

[0002] In the process of geological exploration, whether in the field of coalfield geological exploration or in other mineral resource exploration activities, bifurcations in the borehole are often encountered. During the construction of the exploration borehole, due to the complexity and uncertainty of the geological structure, the alternation of strata with different hardness and different lithology, or the presence of geological structures such as faults, collapse columns and fissures underground, may cause the direction of the borehole to change, thus forming bifurcated holes. If these bifurcated holes cannot be effectively sealed, a series of serious problems will occur. Taking the coalfield geological exploration hole as an example, if gas leaks from the bifurcated hole, a dangerous environment of gas accumulation will be formed in the exploration area. Once an open flame or high temperature source is encountered, it is very easy to cause an explosion accident, posing a direct threat to the life safety of the explorers. At the same time, in the exploration of other mineral resources, groundwater channeling is also a problem that cannot be ignored. The disordered flow of groundwater may wash away the rock cuttings samples in the borehole, destroy the original structural state of the stratum, and then affect the accuracy of the exploration data, causing subsequent judgments on key information such as mineral reserves and distribution range to deviate. Some affect the safety of subsequent mining operations.

[0003] The traditional sealing method usually involves injecting a certain sealing material, such as cement slurry or special sealing glue, into the borehole under a certain pressure, and forming a sealing layer after solidification. This sealing method can still play a certain role in dealing with a single borehole, but when faced with a complex bifurcated hole structure, the traditional sealing method is powerless. The traditional method cannot achieve the ideal sealing effect, which poses a huge safety hazard to exploration operations and subsequent mining operations.

[0004] At present, the bifurcation hole sealing technology in geological exploration has the following shortcomings:

[0005] On the one hand: When a borehole bifurcate occurs, the traditional sealing technology is usually used to seal the bifurcation hole, that is, by injecting cement slurry into the drill pipe, the cement slurry flows into the old wellbore and the new wellbore, so as to seal the new and old wellbores. However, due to the irregular shape of the bifurcation hole, it is difficult to evenly distribute the cement slurry or sealing material to each bifurcation hole. There will often be accumulation of sealing materials at some bifurcations, while other bifurcations are insufficiently sealed or even completely without material filling, resulting in poor wellbore sealing.

[0006] On the other hand: when using the method of orifice pressurization to seal new and old wellbores, especially when cement slurry is used as the sealing material, the cement slurry itself has the characteristics of a liquid. Due to the fluidity and incompressibility of the liquid, the pressure often disperses and is lost during the transmission process, making it difficult to transmit it evenly and efficiently as expected, so that some areas cannot obtain sufficient pressure to drive the cement slurry to fill the gaps and spaces in the wellbore. Especially in some complex wellbore structures, such as the presence of bends, branches, or junctions of different lithological layers in the wellbore trajectory, the unevenness of pressure transmission is more prominent, resulting in a significant reduction in the sealing effect. It is difficult to ensure that the new and old wellbores can be completely and completely sealed, and they are prone to become leakage channels, thereby bringing great risks and uncertainties to the stability, safety, and subsequent mining, construction, and other operations of the entire project. It is impossible to effectively meet the high standards and strict requirements required for the sealing operation, which may ultimately lead to serious impacts on the quality and benefits of the entire project.

[0007] Third aspect: At present, in the process of sealing old and new wellbores using sealing devices, there is only a vague qualitative expression due to the lack of an accurate measurement formula specifically for the sealing pressure of the sealing device, which brings many inconveniences and disadvantages to the sealing construction. It is difficult for construction personnel to accurately determine at what sealing pressure both effective sealing and formation fracture pressure limit can be achieved. This may lead to loose sealing, and it is difficult to hold back pressure during the splitting process of the sandwich wall between the new and old wellbores, resulting in leakage, or the fracture of the far formation due to excessive pressure, resulting in serious consequences such as damage to the far formation structure and disturbance of the groundwater system, which greatly affects the quality and safety of the sealing construction and increases the project risk and cost. Summary of the invention

[0008] The purpose of the present invention is to provide a geological exploration bifurcation hole sealing device and method to solve the problems existing in the prior art, realize segmented splitting, full-section sealing or partial sealing in one entry into the well, and solve the problem of difficulty in sealing bifurcation holes in ground exploration holes with greater depth.

[0009] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a geological exploration bifurcation hole sealing device, including a pipe body, one end of the pipe body is provided with an opening, and the other end is sealed, the pipe body includes a communicating grouting pipe, a stabilizer, an injector and a sealing pipe, a plurality of nozzles are evenly arranged on the ring of the injector, and the nozzles are detachable, the grouting pipe includes an outer sleeve, the outer sleeve is provided with a circulation hole, and a slidable lower sleeve and a closing sleeve are provided inside the outer sleeve.

[0010] The lower sleeve and the closing sleeve are both round tubes. The closing sleeve is arranged on the side close to the opening. The fixed sleeve in the lower sleeve is provided with a gravity plug seat, and the fixed sleeve in the closing sleeve is provided with a rubber plug seat. The lower sleeve abuts against the closing sleeve, and the gravity plug seat abuts against the rubber plug seat.

[0011] A first through hole is arranged in the gravity plug seat, and a second through hole is arranged in the rubber plug seat. The diameter of the second through hole is greater than the diameter of the first through hole.

[0012] A ball seat is arranged at one end of the grouting pipe away from the opening.

[0013] The isolation pipe comprises a central pipe, an annular groove is arranged on the central pipe, a liquid hole is arranged on the outer side of the annular groove, a slidable closing valve is arranged in the annular groove, and an expansion capsule is sleeved on the outer side of the central pipe.

[0014] The height of the annular groove along the length direction of the isolation tube is greater than the diameter of the liquid hole, the height of the closing valve along the length direction of the isolation tube is greater than the diameter of the liquid hole and less than the height of the annular groove, and a third through hole is provided in the closing valve.

[0015] The lowering sleeve and the grouting pipe, the closing sleeve and the grouting pipe, the lowering sleeve and the gravity plug seat, the closing sleeve and the rubber plug seat, and the closing valve and the isolation pipe are all connected by pins.

[0016] The outer wall of the central tube is also sleeved with a first floating head and a second floating head, which are respectively located at the two ends of the expansion capsule and connected to the expansion capsule. The outer wall of the isolation tube is also sleeved with an upper joint, which is arranged at one end of the isolation tube close to the ejector. There are gaps between the first floating head and the second joint, and between the second floating head and the upper joint.

[0017] A method for sealing a bifurcated hole in geological exploration comprises the following steps:

[0018] Step 1: Before sealing the new and old wellbores, first determine the intersection position, number, aperture size and other parameters of the new and old wellbores according to the logging trajectory data, then select the geological exploration bifurcation hole sealing device of appropriate specifications and determine the position of lowering the geological exploration bifurcation hole sealing device. For deeper holes, the lower section of the intersection position of the borehole, that is, the lower part of the new wellbore, can be sealed by conventional sealing methods first, and then the bifurcation hole can be sealed by the geological exploration bifurcation hole sealing device after the cement solidifies for 48 hours. After the isolation pipe, ejector, centralizer and grouting pipe are connected in sequence, the pipe string is connected to the end of the pipe body with an opening. At this time, the geological exploration bifurcation hole sealing device is in the initial position, the circulation hole is in a closed state, and the liquid hole is in an open state;

[0019] The conventional sealing method is: if cement mortar is used to seal the hole, cement, sand and water must be mixed in proportion and stirred evenly. The mortar is sent to the bottom of the hole through the grouting pipe with a sealing pump, and grouting is performed while the pipe column is lifted until the mortar fills the sealing section.

[0020] Step 2: Inject high-pressure liquid into the pipe string, with a pumping pressure of about 5-10MPa. The high-pressure liquid enters the pipe body from the opening and penetrates into the expansion capsule through the liquid hole. The expansion capsule absorbs the liquid and expands under a certain pressure difference and comes into close contact with the hole wall. A first-level rubber plug or steel ball matching the shut-off valve is put into the pipe body and pressurized with a drilling pump at a pressure between 15-20MPa. The first-level rubber plug or steel ball sits on the shut-off valve. Under the action of high pressure, the shut-off valve cuts off the pin, and the shut-off valve moves downward along the annular groove of the isolation pipe to close the liquid hole.

[0021] Step 3: Continue to increase the pressure through the high-pressure pump and inject high-pressure liquid into the pipe string. The high-pressure liquid is ejected through the nozzle of the ejector, thereby splitting the sandwich wall between the new and old wellbores, connecting the new and old wellbores through artificial fractures, which is conducive to the later cement slurry flowing from the new wellbore into the old wellbore to seal the old wellbore;

[0022] Step 4: Put a secondary steel ball or rubber plug into the pipe string. The secondary steel ball or rubber plug is seated on the ball seat at the top of the ejector to seal the isolation pipe and the ejector.

[0023] Step 5: Put a three-level rubber plug or steel ball matching the gravity plug seat into the pipe body and pressurize it. The three-level rubber plug or steel ball is seated on the gravity plug seat, cutting off the pin between the lower sleeve and the gravity plug seat and driving the lower sleeve to move. The pin between the lower sleeve and the outer casing is cut off and moves downward, opening the circulation hole and circulating the drilling fluid.

[0024] Step 6: Inject cement slurry through the opening, and the cement slurry enters the splitting channel of the sandwich wall between the new and old wellbores through the circulation hole to achieve the purpose of sealing the old wellbore, and the cement slurry is replaced by liquid;

[0025] Step 7: Put a four-stage rubber plug or steel ball matching the rubber plug seat into the pipe body. After being pressed by high-pressure liquid, the four-stage rubber plug or steel ball sits on the rubber plug seat, cuts off the pin between the closing sleeve and the rubber plug seat and drives the closing sleeve to move downward, cuts off the pin between the closing sleeve and the outer sleeve and moves downward, closes the circulation hole, and waits for the cement slurry to solidify;

[0026] Step 8: After the cement slurry solidifies for 10-20 minutes, remove the geological exploration bifurcation hole sealing device to complete the bifurcation hole sealing work.

[0027] In step 2, the expanded capsule absorbs the liquid at a certain pressure difference P w Downward expansion,

[0028] In order to effectively seal the isolation pipe, the setting pressure of the isolation pipe should be W =F f The following relationship is satisfied: ① In order to prevent the isolation tube from being pushed out by high-pressure water, F f Should be greater than Fw ; ② Ensure that there is no high-pressure water overflow between the isolation pipe and the borehole wall, P e Should be greater than P w .

[0029] When the pipe string is hung at the wellhead using the wellhead hanger, the isolation pipe does not bear the deadweight of the pipe string in the borehole, but is only affected by water pressure and friction. According to the principle of statics, the equilibrium equation between the isolation pipe and the borehole wall is established: F W =F f , namely μP e S1=P w S2

[0030] Among them, F w F is the force on the isolation pipe in the borehole under the action of water pressure, f is the friction between the isolation tube and the borehole wall, μ is the friction coefficient between the expansion capsule surface and the borehole wall, which is taken as 0.2, P e is the pressure on the hole wall, P w is the water pressure in the borehole, which is equivalent to the setting pressure, S1 is the contact area between the expansion capsule and the borehole, S1=πDL' e ; S2 is the cross-sectional area of ​​the expansion capsule in the borehole after expansion,

[0031] Since the high-pressure water first flows through the isolation tube, enters from the liquid hole to expand the expansion capsule with a certain pressure, and the remaining liquid flows out from the nozzle of the ejector, at this time, due to the partial pressure loss of the expansion capsule, the final effective pressure P acting on the borehole wall e for

[0032] P e =P 入 -P 胶囊

[0033] Where P 胶囊 is the expansion pressure of the expansion capsule, and is also the pressure when the expansion capsule is fully expanded; P 入 The water pressure input to the string.

[0034] For a single-sealed capsule, the length of the effective portion that can contact the hole wall and generate friction is not equal to the length of the entire capsule. The effective sealing length L' e , the effective sealing length L' of the expansion capsule e for:

[0035] L' e ≈L-0.8D

[0036] Where D is the diameter of the drill hole; L is the length of the expansion capsule; L' e is the effective length of the expansion capsule, and P is obtained by substituting the above formula intow .

[0037] The present invention adopts the above technical scheme and has the following advantages: the geological exploration bifurcation hole sealing device of the present invention, in the process of bifurcation hole sealing, opens one end of the tube body and seals the other end, injects high-pressure liquid into the tube body through the opening, and the high-pressure liquid enters the tube body and penetrates into the expansion capsule through the set liquid hole. Under the action of pressure difference, the expansion capsule absorbs the high-pressure liquid and then expands and holds the pressure and contacts closely with the well wall, so that the isolation pipe is sealed. When the expansion capsule absorbs the high-pressure liquid and expands to the maximum, the liquid hole is closed by throwing a ball, so as to avoid the expansion capsule of the isolation pipe from continuing to expand and lose its life under the action of the pressure difference of the high-pressure liquid in the later stage. Then, by injecting high-pressure liquid into the tube body, the high-pressure liquid is ejected from the nozzle of the ejector to split the sandwich wall between the new and old wellbores. Subsequently, the ejector is closed by throwing a ball into the tube body through the opening to prevent the ejector nozzle from being blocked by cement slurry in the later stage. After the ejector is closed, cement slurry is injected from the opening, and the cement slurry flows into the old wellbore from the artificial cracks of the split sandwich wall through the set circulation hole. After the cement slurry fills the gap of the old wellbore, the circulation hole is closed by throwing a ball to complete the sealing work. The present invention can not only realize the full-well section sealing of the new and old wellbores of the bifurcated hole, but also the partial sealing, and realizes the segmented splitting between the sandwich wall of the new and old wellbores through the ejector, provides an artificial channel for the flow of cement slurry, and blocks the isolation pipe and the ejector by throwing balls to prevent the cement slurry from consolidating the tools in the hole in the later stage. The present invention is lowered into the well together with the pipe string during the lowering process, realizes the segmented splitting, full-well section sealing or partial sealing in one time, and after the sealing is completed, the drilling tool is lifted up, which solves the problem of difficulty in sealing bifurcated holes in ground exploration holes with greater depth, and also provides certain guidance and reference for the sealing of other bifurcated boreholes.

[0038] The present invention will be further described below in conjunction with specific implementations and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a schematic diagram of the force applied to the isolation pipe of a geological exploration bifurcated hole sealing device when it is set;

[0040] Figure 2 It is a schematic diagram of the present invention at the intersection of the new and old wellbores;

[0041] Figure 3 It is a structural schematic diagram of a geological exploration bifurcation hole sealing device of the present invention;

[0042] Figure 4 It is a structural schematic diagram of a sealing pipe of a geological exploration bifurcated hole sealing device according to the present invention;

[0043] Figure 5 It is a structural schematic diagram of a grouting pipe of a geological exploration bifurcated hole sealing device of the present invention;

[0044] Figure 6 The present invention is a state diagram of a geological exploration bifurcation hole sealing device during construction.

[0045] In the figure,

[0046] 1-thread plug, 2-second joint, 3-first floating head, 4-expansion capsule, 5-center tube, 6-shut-off valve, 7-pin, 8-ring groove, 9-second floating head, 10-upper joint, 11-nozzle, 12-injector, 13-centralizer, 14-first through hole, 15-second through hole, 16-outer sleeve, 17-gravity plug seat, 18-lower sleeve, 19-circulation hole, 20-shut-off sleeve, 21-rubber plug sleeve, 22-first joint, 23-tube body, 24-ball seat, 25-opening, 26-third through hole. DETAILED DESCRIPTION

[0047] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0048] The initial position herein refers to the working state of the present invention when entering the geological exploration hole, which is consistent with the direction of drilling, and is called the front section.

[0049] Example 1

[0050] like Figure 3-5 As shown, a geological exploration bifurcation hole sealing device includes a tube body 23, one end of the tube body 23 is provided with an opening 25, and the other end is sealed. The tube body 23 includes a grouting pipe, a centralizer 13, an injector 12 and a sealing pipe that are connected to each other. The opening 25 is arranged at one end of the grouting pipe, and the sealing end is arranged at the end of the sealing pipe. The centralizer 13 is connected to the grouting pipe by a thread, one end of the injector 12 is threadedly connected to the centralizer 13, and the other end of the injector 12 is threadedly connected to the sealing pipe.

[0051] The centralizer 13 is mainly used to stabilize the geological exploration bifurcation hole sealing device in the bifurcation hole to prevent deflection;

[0052] The ejector 12 is mainly used for splitting the sandwich wall between the bifurcated holes of the new and old wells, providing a channel for the uniform flow of cement slurry and effectively sealing the old wellbore. A plurality of nozzles 11 are evenly arranged on the ring of the ejector 12. The nozzles 11 are detachable. Nozzles 11 of different apertures are used for sandwich walls of different thicknesses to obtain different pressures.

[0053] The grouting pipe includes an outer sleeve 16, on which a circulation hole 19 is provided, and inside the outer sleeve 16 there are a slidable lower sleeve 18 and a closing sleeve 20, wherein the lower sleeve 18 can control the closing and opening of the circulation hole 19, and the closing sleeve 20 can control the closing of the circulation hole 19;

[0054] The lower sleeve 18 and the closing sleeve 20 are both round tubes and are slidably arranged in the grouting pipe. The closing sleeve 20 is arranged on the side close to the opening 25. The fixed sleeve in the lower sleeve 18 is provided with a gravity plug seat 17, and the fixed sleeve in the closing sleeve 20 is provided with a rubber plug seat 21. The gravity plug seat 17 is provided with a first through hole 14, and the rubber plug seat 21 is provided with a second through hole 15. The diameter of the second through hole 15 is greater than that of the first through hole 14. The lower sleeve 18 abuts against the closing sleeve 20, and the gravity plug seat 17 abuts against the rubber plug seat 21.

[0055] A ball seat 24 is provided at one end of the grouting pipe away from the opening 25. The ball seat 24 maintains a preset distance with the gravity plug seat 17 and the gravity plug seat 17 can be stuck on the ball seat 24. The gravity plug seat 17 can slide within the preset distance to open the circulation hole 19; in the initial position, the lower sleeve 18 covers the circulation hole 19.

[0056] The isolation tube includes a central tube 5, on which an annular groove 8 is provided, and a plurality of liquid holes are evenly arranged on the outer side of the annular groove 8. The height of the annular groove 8 along the length direction of the isolation tube is greater than the diameter of the liquid holes. A slidable shut-off valve 6 is provided in the annular groove 8. The sliding of the shut-off valve 6 can control the closing and opening of the liquid holes. The height of the shut-off valve 6 along the length direction of the isolation tube is greater than the diameter of the liquid holes and less than the height of the annular groove 8. A third through hole 26 is provided in the shut-off valve 6. An expansion capsule 4 is sleeved on the outside of the central tube 5, and the expansion capsule 4 expands after absorbing liquid from the liquid holes.

[0057] In the initial position, the closing valve 6 is in a position where it fails to cover the liquid hole, and the liquid hole is communicated with the third through hole 26 in this position.

[0058] The lower sleeve 18 and the grouting pipe, the closing sleeve 20 and the grouting pipe, the lower sleeve 18 and the gravity plug seat, the closing sleeve 20 and the rubber plug seat, and the closing valve 6 and the isolation pipe are all connected by pins 7.

[0059] The two ends of the pipe body 23 are respectively provided with a first joint 22 and a second joint 2. The first joint 22 is provided on the grouting pipe, and the second joint 2 is provided on the isolation pipe. The second joint 2 is provided with a thread plug 1 to seal the end of the isolation pipe.

[0060] The outer wall of the center tube 5 is also sleeved with a first floating head 3 and a second floating head 9, which are respectively located at the two ends of the expansion capsule 4 and connected to the expansion capsule 4. The outer wall of the isolation tube is also sleeved with an upper joint 10, which is arranged at one end of the isolation tube close to the injector 12. There are gaps between the first floating head 3 and the second joint 9, and between the second floating head 9 and the upper joint 10.

[0061] The first floating head 3 and the second floating head 9 are used to fix the expansion capsule 4 to enhance the stability of the expansion capsule 4 .

[0062] In the process of sealing the bifurcated hole in the geological exploration bifurcated hole of the present invention, one end of the tube body 23 is sealed, and high-pressure liquid is injected into the tube body 23 through the opening 25 at the other end of the tube body 23. After the high-pressure liquid enters the tube body 23, it penetrates into the expansion capsule 4 through the provided liquid-passing hole. After absorbing the high-pressure liquid, the expansion capsule 4 expands under the action of the pressure difference and comes into close contact with the well wall, so that the isolation pipe is sealed. The liquid-passing hole is closed by sliding the closing valve 6, so that the expansion capsule 4 is prevented from continuing to expand in the later stage and reducing its service life. At the same time, by injecting high-pressure liquid into the tube body 23, the high-pressure liquid The ejector 12 is used to spray out the cement slurry from the nozzle 11 to split the sandwich wall between the new and old wellbores, thereby providing a channel for the flow of cement slurry at a later time; then, a ball is thrown into the pipe body 23 through the opening 25 to close the ejector 12, thereby preventing the cement slurry at a later time from blocking the nozzle 11 of the ejector 12; after the ejector 12 is closed, cement slurry is injected through the opening 25, and the cement slurry flows into the old wellbore from the artificial cracks in the split sandwich wall through the circulation holes 19 provided on the grouting pipe, so that the cement slurry fills the gap and returns to the ground, and then the circulation holes 19 are closed by throwing a ball to complete the sealing work of the new and old wellbores.

[0063] The present invention can not only realize the full well section closure of the new and old wellbore of the bifurcated hole, but also partial closure, and realize the segmented splitting between the sandwich wall of the new and old wellbore through the ejector 12, provide an artificial channel for the flow of cement slurry, and block the isolation pipe and the ejector 12 by throwing balls to prevent the cement slurry from consolidating in the later stage. The present invention is put into the well together with the pipe string during the lowering process, and realizes the segmented splitting, full well section sealing or partial sealing in one time. After the sealing is completed, the drilling tool is lifted up, which solves the problem of difficulty in sealing bifurcated holes in ground exploration holes with large depths, and also provides certain guidance and reference for the sealing of other bifurcated drilling holes.

[0064] In order to effectively seal the isolation pipe, the setting pressure of the isolation pipe should be Figure 1 As shown, F W =F f The following relationship is satisfied: ① In order to prevent the isolation tube from being pushed out by high-pressure water, F f Should be greater than F w ; ② Ensure that there is no high-pressure water overflow between the isolation pipe and the borehole wall, P e Should be greater than P w .

[0065] When the pipe string is hung at the wellhead using the wellhead hanger, the isolation pipe does not bear the deadweight of the pipe string in the borehole, but is only affected by water pressure and friction. According to the principle of statics, the equilibrium equation between the isolation pipe and the borehole wall is established: F W =F f ,Right now

[0066] μP e S1=P wS2 (1)

[0067] Among them, F w F is the force on the isolation pipe in the borehole under the action of water pressure, f is the friction between the isolation tube and the borehole wall, μ is the friction coefficient between the surface of the expansion capsule 4 and the borehole wall, which is taken as 0.2, P e is the pressure on the hole wall, P w is the water pressure in the borehole, which is equivalent to the setting pressure, S1 is the contact area between the expansion capsule 4 and the borehole, S1=πDL' e ; S2 is the cross-sectional area of ​​the expansion capsule 4 in the borehole after expansion,

[0068] Since the high-pressure water first flows through the isolation tube, enters from the liquid hole to expand the expansion capsule 4 with a certain pressure, and the remaining liquid flows out from the nozzle 11 of the ejector 12, at this time, due to the partial pressure loss of the expansion capsule 4, the effective pressure P acting on the borehole wall is e for

[0069] P e =P 入 -P 胶囊 (2)

[0070] Where P 胶囊 is the expansion pressure of the expansion capsule 4, and is also the pressure when the expansion capsule 4 is fully expanded; P 入 The water pressure input to the string.

[0071] For a single-sealed capsule, the length of the effective portion that can contact the hole wall and generate friction is not equal to the length of the entire capsule. The effective sealing length L' e According to the empirical formula, the effective sealing length L' of the expansion capsule 4 is e for:

[0072] L' e ≈L-0.8D(3)

[0073] Wherein, D is the diameter of the drill hole; L is the length of the expansion capsule 4; L' e is the effective length of the expansion capsule 4. Substituting the above formula into the equation, we get:

[0074]

[0075] The circulation hole 19 serves as a circulation channel for the drilling fluid and cement slurry.

[0076] Example 2

[0077] Taking a coal mine in Anhui as an example, a bifurcation of the wellbore occurred during the construction of the ground exploration hole. In order to effectively seal the new and old wellbores and prevent the formation aquifer from seeping into the mine through the old wellbore due to poor drilling closure, it would cause certain safety hazards to the subsequent large tunnel excavation and coal mining work.

[0078] The geological exploration hole depth is 1100-1300m, and the main rock type of 0-500m is the Quaternary loose layer. A geological exploration hole is implemented from the ground. Taking the second opening well body structure as an example, the drilling tool is used to clear the well before the geological exploration bifurcation hole sealing device is lowered. The first opening of the vertical well is 0-500m deep, the well diameter is 168.00mm, and it is a bare hole; the second opening is 500-1300m deep, the well diameter is 94.00mm, and it is a bare hole. Because there are problems of old wellbore and new wellbore after 220 meters during the drilling process, the wellbore trajectories of the new and old wellbores intersect at 550-600m, and the sandwich wall is thick, that is, the bifurcation hole sealing method is adopted. The first stage is sealed from the bottom of the hole to 620 meters, and the hole is sealed while the drill is lifted to ensure that the bottom of the drill is about 30 meters below the cement slurry surface. After the first stage of cement solidifies for 48 to 72 hours, the second stage of sealing begins. In order to prevent poor sealing of the borehole during the sealing process, the present invention provides a geological exploration bifurcation hole sealing method for the problem of the second stage of bifurcation hole sealing, such as Figure 6 As shown, the specific implementation is as follows:

[0079] Step 1: After the drilling is completed, when new and old wellbores appear, before the new and old wellbores are sealed, first determine the intersection position, number, aperture size and other parameters of the new and old wellbores based on the logging trajectory data, such as depth, zenith angle and azimuth, and then select a geological exploration bifurcation hole sealing device of appropriate specifications and determine the position where the geological exploration bifurcation hole sealing device is lowered. For deeper holes, the lower section of the intersection position of the drilling hole, that is, the lower part of the new wellbore, can be sealed using a conventional sealing method. After the cement solidifies for 48 hours, the bifurcation hole can be sealed using the geological exploration bifurcation hole sealing device. After the isolation pipe, ejector 12, centralizer 13 and grouting pipe are connected in sequence, the pipe string is connected to the end of the pipe body 23 with an opening 25. At this time, the geological exploration bifurcation hole sealing device is in the initial position, the circulation hole 19 is in a closed state, and the liquid hole is in an open state;

[0080] The conventional sealing method is: if cement mortar is used to seal the hole, cement, sand and water must be mixed in proportion and stirred evenly. The mortar is sent to the bottom of the hole through the grouting pipe with a sealing pump, and grouting is performed while the pipe column is lifted until the mortar fills the sealing section.

[0081] Step 2: Use a drilling pump to inject high-pressure liquid into the pipe string, with a pumping pressure of about 5-10 MPa. The high-pressure liquid enters the pipe body 23 from the opening 25, and penetrates into the expansion capsule 4 through the liquid hole. The expansion capsule 4 absorbs the liquid and expands under a certain pressure difference and comes into close contact with the hole wall. A first-level rubber plug or steel ball matching the shut-off valve 6 is put into the pipe body 23, and the drilling pump is used to pressurize the pressure to between 15-20 MPa. The first-level rubber plug or steel ball is seated on the shut-off valve 6. Under the action of high pressure, the shut-off valve 6 cuts off the pin 7, and the shut-off valve 6 moves downward along the annular groove 8 of the isolation pipe to close the liquid hole.

[0082] Step 3: Continue to increase the pressure through the high-pressure pump and inject high-pressure liquid into the pipe string. The high-pressure liquid is ejected through the nozzle 11 of the ejector 12. Under the control of pump pressure, displacement and nozzle size, the high-pressure liquid converts pressure energy into kinetic energy according to the Bernoulli principle. The rock formation can be broken under the condition of certain kinetic energy, thereby splitting the sandwich wall between the new and old wellbores, connecting the new and old wellbores through artificial cracks, which is conducive to the later cement slurry flowing from the new wellbore into the old wellbore to seal the old wellbore;

[0083] Step 4: Put a secondary steel ball or rubber plug into the pipe column. The secondary steel ball or rubber plug is seated on the ball seat 24 at the top of the injector 12 to seal the isolation pipe and the injector 12, so as to prevent the cement slurry from flowing out of the nozzle 11 of the injector 12 in the later stage, making it difficult to lift the geological exploration bifurcation hole sealing device;

[0084] Step 5: A three-level rubber plug or steel ball matching the gravity plug seat 17 is put into the pipe body 23 through the pipe string to pressurize. The three-level rubber plug or steel ball is seated on the gravity plug seat 17, and the pin 7 between the lower sleeve 18 and the gravity plug seat 17 is cut off and the lower sleeve 18 is driven to move. The pin 7 between the lower sleeve 18 and the outer casing 16 is cut off and moves downward, and the circulation hole 19 is opened to circulate the drilling fluid;

[0085] Step 6: inject cement slurry through the opening 25, and the cement slurry enters the splitting channel of the sandwich wall between the new and old wellbores through the circulation hole 19 to achieve the purpose of sealing the old wellbore, and the cement slurry is replaced by high-pressure liquid;

[0086] Step 7: A fourth-level rubber plug or steel ball matching the rubber plug seat 21 is put into the pipe body through the pipe column. After being pressurized by high-pressure liquid, the fourth-level rubber plug or steel ball is seated on the rubber plug seat 21, the pin 7 between the closing sleeve 20 and the rubber plug seat 21 is cut off and the closing sleeve 20 is driven to move downward. The pin 7 between the closing sleeve 20 and the outer sleeve 16 is cut off and moves downward, the circulation hole 19 is closed, and the cement slurry is waited for solidification;

[0087] Step 8: After the cement slurry solidifies for 10-20 minutes, remove the geological exploration bifurcation hole sealing device to complete the bifurcation hole sealing work.

[0088] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. The examples of the implementation methods and the parts not described in detail are common knowledge of ordinary technicians in the field. For those skilled in the art, they can still modify the technical solutions recorded in the above embodiments, or replace some of the technical features therein with equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A geological exploration bifurcation hole sealing device, characterized in that: The invention comprises a pipe body (23), one end of which is provided with an opening (25) and the other end is sealed. The pipe body (23) comprises a grouting pipe, a centralizer (13), an ejector (12) and a sealing pipe which are connected to each other. A plurality of nozzles (11) are evenly arranged on the ring of the ejector (12). The nozzles (11) are detachable. The grouting pipe comprises an outer sleeve (16). The outer sleeve (16) is provided with a circulation hole (19). A slidable lower sleeve (18) and a closing sleeve (20) are arranged inside the outer sleeve (16).

2. A geological exploration bifurcation hole sealing device according to claim 1, characterized in that: The lower sleeve (18) and the closing sleeve (20) are both round tubes. The closing sleeve (20) is arranged on a side close to the opening (25). A gravity plug seat (17) is arranged inside the lower sleeve (18), and a rubber plug seat (21) is arranged inside the closing sleeve (20). The lower sleeve (18) abuts against the closing sleeve (20), and the gravity plug seat (17) abuts against the rubber plug seat (21).

3. A geological prospecting bifurcation hole sealing device according to claim 2, characterized in that: The gravity plug seat (17) is provided with a first through hole (14), the rubber plug seat (21) is provided with a second through hole (15), and the diameter of the second through hole (15) is greater than the diameter of the first through hole (14).

4. A geological prospecting bifurcation hole sealing device according to claim 3, characterized in that: A ball seat (24) is provided at one end of the grouting pipe away from the opening (25).

5. A geological prospecting bifurcation hole sealing device according to claim 4, characterized in that: The isolation tube comprises a central tube (5), an annular groove (8) is provided on the central tube (5), a liquid passage hole is provided on the outer side of the annular groove (8), a slidable closing valve (6) is provided in the annular groove (8), and an expansion capsule (4) is sleeved on the outer side of the central tube (5).

6. A geological prospecting bifurcation hole sealing device according to claim 5, characterized in that: The height of the annular groove (8) along the length direction of the isolation tube is greater than the diameter of the liquid hole, the height of the closing valve (6) along the length direction of the isolation tube is greater than the diameter of the liquid hole and less than the height of the annular groove (8), and a third through hole (26) is provided in the closing valve (6).

7. A geological prospecting bifurcation hole sealing device according to claim 6, characterized in that: The lower sleeve (18) and the grouting pipe, the closing sleeve (20) and the grouting pipe, the lower sleeve (18) and the gravity plug seat, the closing sleeve (20) and the rubber plug seat, and the closing valve (6) and the isolation pipe are all connected via pins (7).

8. A geological prospecting bifurcated hole sealing device according to claim 7, characterized in that: The outer wall of the central tube (5) is also sleeved with a first floating head (3) and a second floating head (9), which are respectively located at the two ends of the expansion capsule (4) and connected to the expansion capsule (4). The outer wall of the isolation tube is also sleeved with an upper joint (10), which is arranged at one end of the isolation tube close to the ejector (12). Gaps are provided between the first floating head (3) and the second joint (9), and between the second floating head (9) and the upper joint (10).

9. A method for sealing a bifurcated hole in geological exploration, characterized in that: The steps include: Step 1: Before sealing the new and old wellbores, first determine the intersection position, number, aperture size and other parameters of the new and old wellbores according to the logging trajectory data, then select a geological exploration bifurcation hole sealing device of appropriate specifications and determine the position to lower the geological exploration bifurcation hole sealing device. For deep holes, the lower section of the intersection position of the borehole, i.e., the lower part of the new wellbore, can be sealed using a conventional sealing method first. After the cement solidifies for 48 hours, the bifurcation hole is sealed using the geological exploration bifurcation hole sealing device. After the isolation pipe, the ejector (12), the centralizer (13) and the grouting pipe are connected in sequence, the pipe column is connected to one end of the pipe body (23) provided with an opening (25). At this time, the geological exploration bifurcation hole sealing device is in the initial position, the circulation hole (19) is in a closed state, and the liquid hole is in an open state; The conventional sealing method is: if cement mortar is used for sealing, cement, sand and water must be mixed in proportion and stirred evenly. The mortar is sent to the bottom of the hole through the grouting pipe by a sealing pump, and the grouting is performed while the pipe column is lifted until the mortar fills the sealing section. Step 2: inject high-pressure liquid into the pipe column, the pumping pressure is about 5-10MPa, the high-pressure liquid enters the pipe body (23) from the opening (25), and penetrates into the expansion capsule (4) through the liquid hole. The expansion capsule (4) absorbs the liquid and expands under a certain pressure difference and comes into close contact with the hole wall. A first-level rubber plug or steel ball matching the shut-off valve (6) is put into the pipe body (23), and the pressure is between 15-20MPa by using a drilling pump. The first-level rubber plug or steel ball is seated on the shut-off valve (6). Under the action of high pressure, the shut-off valve (6) cuts off the pin (7), and the shut-off valve (6) moves downward along the annular groove (8) of the isolation pipe to close the liquid hole; Step 3: Continue to increase the pressure through the high-pressure pump and inject high-pressure liquid into the pipe string. The high-pressure liquid is ejected through the nozzle (11) of the ejector (12), thereby splitting the sandwich wall between the new and old wellbores, connecting the new and old wellbores through artificial fractures, and facilitating the flow of cement slurry from the new wellbores into the old wellbores in the later stage, thereby sealing the old wellbores; Step 4: inserting a secondary steel ball or rubber plug into the pipe column, the secondary steel ball or rubber plug is seated on the ball seat (24) at the top of the ejector (12), so as to seal the isolation pipe and the ejector (12); Step 5: A third-level rubber plug or steel ball matching the gravity plug seat (17) is put into the pipe body (23) to pressurize. The third-level rubber plug or steel ball is seated on the gravity plug seat (17), and the pin (7) between the lower sleeve (18) and the gravity plug seat (17) is cut off and the lower sleeve (18) is driven to move. The pin (7) between the lower sleeve (18) and the outer sleeve (16) is cut off and moved downward, and the circulation hole (19) is opened to circulate the drilling fluid. Step 6: inject cement slurry through the opening (25), and the cement slurry enters the splitting channel of the sandwich wall between the new and old wellbores through the circulation hole (19) to achieve the purpose of sealing the old wellbore, and the cement slurry is replaced by liquid; Step 7: A fourth-level rubber plug or steel ball matching the rubber plug seat (21) is inserted into the pipe body. After being pressed by high-pressure liquid, the fourth-level rubber plug or steel ball is seated on the rubber plug seat (21), the pin (7) between the closing sleeve (20) and the rubber plug seat (21) is cut off, and the closing sleeve (20) is driven to move downward. The pin (7) between the closing sleeve (20) and the outer sleeve (16) is cut off and moves downward, the circulation hole (19) is closed, and the cement slurry is waited for solidification; Step 8: After the cement slurry solidifies for 10-20 minutes, remove the geological exploration bifurcation hole sealing device to complete the bifurcation hole sealing work.

10. A method for sealing a bifurcated hole in geological exploration according to claim 9, characterized in that: In step 2, the expansion capsule (4) absorbs the liquid at a certain pressure difference P w Downward expansion, In order to effectively seal the isolation pipe, the setting pressure of the isolation pipe should be W =F f The following relationship is satisfied: ① In order to prevent the isolation tube from being pushed out by high-pressure water, F f Should be greater than F w ; ② Ensure that there is no high-pressure water overflow between the isolation pipe and the borehole wall, P e Should be greater than P w ; When the pipe string is hung at the wellhead using the wellhead hanger, the isolation pipe does not bear the deadweight of the pipe string in the borehole, but is only affected by water pressure and friction. According to the principle of statics, the equilibrium equation between the isolation pipe and the borehole wall is established: F W =F f , namely μP e S1=P w S2; Among them, F w F is the force on the isolation pipe in the borehole under the action of water pressure, f is the friction force between the isolation tube and the borehole wall, μ is the friction coefficient between the surface of the expansion capsule (4) and the borehole wall, which is taken as 0.2, and P e is the pressure on the hole wall, P w is the water pressure in the borehole, which is equivalent to the setting pressure, S1 is the contact area between the expansion capsule (4) and the borehole, S1=πDL' e ; S2 is the cross-sectional area of ​​the expansion capsule (4) in the borehole after expansion, Since the high-pressure water first flows through the isolation tube, enters from the liquid hole to expand the expansion capsule (4) with a certain pressure, and the remaining liquid flows out from the nozzle (11) of the ejector (12), at this time, due to the partial pressure loss of the expansion capsule (4), the final effective pressure P acting on the borehole wall is e for P e =P 入 -P 胶囊 Where P 胶囊 is the expansion pressure of the expansion capsule (4), and is also the pressure when the expansion capsule (4) is fully expanded; P 入 The water pressure input to the string; For a single-sealed capsule, the length of the effective portion that can contact the hole wall and generate friction is not equal to the length of the entire capsule. The effective sealing length L' e , the effective sealing length L' of the expansion capsule (4) e for: The e ≈L-0.8D Wherein, D is the diameter of the drill hole; L is the length of the expansion capsule (4); L' e is the effective length of the expansion capsule (4), and the above formula is substituted to obtain P w .

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