Bridge plug material downhole drill passability prediction method, apparatus, and storage medium

Abstract

This invention provides a method, device, and storage medium for predicting the passability of bridging and plugging materials in downhole drilling tools. The method includes the following steps: S1, establishing a prediction model for the passability of bridging and plugging materials in drilling tools; S2, determining the characteristic particle size value of the plugging slurry; S3, determining the number of variable diameter locations and inlet / outlet diameters of the downhole drilling tool assembly; S4, measuring the density and apparent viscosity of the plugging slurry base; S5, calculating the critical value for the passability of bridging and plugging materials in drilling tools based on the prediction model; and S6, determining the passability of bridging and plugging materials in drilling tools. The beneficial effects of this invention include: it allows for rapid and accurate determination of the passability of plugging materials in drilling tools based on the current downhole drilling tool assembly, the designed plugging formula, and construction parameters. This provides a more accurate basis for designing plugging formulas and determining plugging construction parameters, reducing the risk of drill string blockage during the plugging process, thereby improving the safety and success rate of plugging construction.

Description

Technical Field

[0001] This invention relates to the field of drilling and completion engineering technology, and in particular to a method, equipment, and storage medium for predicting the passability of downhole drilling tools for bridging and plugging materials. Background Technology

[0002] Well leakage is one of the most common downhole problems in drilling and completion engineering. It delays normal drilling operations, prolongs the drilling cycle, and results in the loss of significant amounts of drilling fluid and plugging materials. In severe cases, it may necessitate sidetracking or even well abandonment, directly causing substantial economic losses. Well leakage can also trigger other drilling problems, such as reducing the rock-carrying efficiency of drilling fluids, affecting wellbore cleaning and causing sand bridges and stuck pipe, interfering with geological logging and normal maintenance of drilling fluid performance, and in severe cases, causing well control problems such as overflows, kicks, and blowouts. It can even lead to necking of salt-gypsum layers and wellbore collapse, resulting in sand accumulation and stuck pipe. Well leakage in reservoir sections will cause reservoir damage, affecting the timely discovery, accurate evaluation, and production capacity of oil and gas reservoirs. Due to its significant direct and indirect hazards, well leakage has become one of the most critical bottleneck problems in drilling and completion engineering.

[0003] Bridging plugs are the most commonly used leak prevention and plugging materials in drilling operations. They are added to the drilling fluid for continuous drilling leak prevention or plugging, or formulated into high-concentration bridging plugs for continuous drilling or plugging during shutdown. Whether used for continuous drilling or shutdown plugging, the bridging plug needs to be delivered to the leaking formation via the drill string assembly. During delivery, the bridging plug needs to pass through narrowing channels such as drill string connections, water holes, screws, MWD (measuring wound deflector), LWD (lubricating wheel chute), guide tools, and check valves. If the size and concentration of the bridging plug are too large, or if the construction parameters are not properly controlled, it can easily cause drill string blockage. Drill string blockage not only directly leads to the failure of plugging operations but also poses significant safety hazards. Removing the blockage also presents considerable difficulties and workload on site. However, currently, the drill string passability of bridging plugs is mainly judged simply based on the one-third bridging rule and the operational experience of the field engineer, or on-site drill string passability test data for downhole plugs. The former is often inaccurate, easily resulting in excessively high concentration size leading to blockage or excessively low concentration size affecting the sealing effect, while the latter is usually difficult to achieve on-site.

[0004] Chinese patent CN111734399A discloses an intelligent plugging method and system for drilling, including: real-time acquisition of flow velocity values; determining whether there is leakage anomaly in the drilling based on the flow velocity difference between the wellbore inlet and outlet; if leakage anomaly exists, calculating the leakage velocity value and its corresponding fracture width and formation strength data to be improved in the leaking layer; outputting the calculation results to an application module that has pre-stored a drilling bridging and plugging scheme database for searching to obtain the optimal drilling bridging and plugging scheme; and verifying the plugging effect on-site using a plugging material performance visualization device.

[0005] Chinese patent CN110147644A discloses a method for designing the particle size distribution of a crack-related leakage bridging and sealing particulate material, comprising the following steps: classifying the sealing material according to particle size; calculating the expected range of characteristic particle size values ​​of the sealing material based on crack width and particle size selection criteria; setting the relative percentage content of each level of sealing material; fitting a particle size distribution curve using a particle size distribution function; calculating the characteristic particle size value of the sealing material based on the particle size distribution curve; determining whether the calculated characteristic particle size value conforms to the expected range of the calculated characteristic particle size value; and finally generating a particle size composition of the sealing material that conforms to the particle size selection criteria.

[0006] However, neither of the above two patents is a method for judging the drill string passability of bridging and plugging materials. Therefore, it is of great significance to establish a method for predicting the downhole drill string passability of bridging and plugging materials, and to determine the size, concentration, and construction parameters of the bridging and plugging materials based on the downhole drill string size parameters, so as to ensure that the plugging materials are safely delivered to the leaking layer through the drill string assembly. Summary of the Invention

[0007] The purpose of this invention is to address at least one of the aforementioned deficiencies in the prior art. One objective of this invention is to provide a method for determining whether bridging and sealing materials have caused drill bit blockage.

[0008] To achieve the above objectives, the present invention provides a method for predicting the passability of downhole drilling tools for bridging and plugging materials.

[0009] The method includes the following steps: S1, establishing a prediction model for the passability of bridging and plugging materials in drilling tools; S2, determining the characteristic particle size value of the plugging slurry; S3, determining the number of variable diameter locations and inlet / outlet diameters of the downhole drilling tool assembly; S4, measuring the density and apparent viscosity of the plugging slurry base; S5, calculating the critical value for the passability of bridging and plugging materials in drilling tools based on the prediction model; S6, judging the passability of bridging and plugging materials in drilling tools.

[0010] According to an exemplary embodiment of the present invention, the step of establishing a drilling tool passability prediction model for bridging and plugging materials may include the following steps: S11, calculating the flow rate of the bridging and plugging slurry at a velocity V in The inlet diameter of the flow into the drill string assembly is d i The outlet diameter is d o At the point of diameter change, the particle velocity N flowing into the channel with the smaller diameter change position in S12. Calculate the maximum particle discharge velocity N at the outlet of the variable diameter position. out，max S13. Calculate the average particle concentration at the outlet of the variable diameter position based on classical experimental data. S14. Calculate the average particle velocity at the outlet of the variable diameter position based on the Free Falling Arch theory. S15. Based on the condition of no blockage at the diameter change position: N in <N out,max Determine the critical conditions for the sealing material to pass through the variable diameter location.

[0011] According to an exemplary embodiment of the present invention, the particle velocity N flowing into the channel with the smaller diameter variation position is... in It can be calculated based on equation (1), which is:

[0012]

[0013] In equation (1), N in The velocity of particles flowing into the channel with a smaller diameter change is expressed as particles / s; d i V represents the inlet diameter at the variable diameter location, in meters (m). in The velocity of the plugging grout flowing into the variable diameter location, m / s; C LCM d represents the volume concentration of the plugging material flowing into the variable diameter location, dimensionless; p denoted as particle diameter, in meters (m).

[0014] According to an exemplary embodiment of the present invention, the maximum particle discharge velocity N at the variable diameter outlet is... out，max It can be calculated based on equation (2); equation (2) is:

[0015]

[0016] In equation (2), N out，max The maximum particle discharge velocity at the outlet of the variable diameter position, particles / s; The average particle concentration at the outlet of the variable diameter position is dimensionless. The average particle velocity at the outlet of the variable diameter position is given in m / s; d o The outlet diameter at the variable diameter location is in meters (m); d p denoted as particle diameter, in meters (m).

[0017] According to an exemplary embodiment of the present invention, the average particle concentration at the outlet of the variable diameter position... It can be calculated based on equation (3), which is:

[0018]

[0019] In equation (3), The average particle concentration at the outlet of the variable diameter position is dimensionless; e is the natural constant; d o The outlet diameter at the variable diameter location is in meters (m); d p denoted as particle diameter, in meters (m).

[0020] According to an exemplary embodiment of the present invention, the average particle velocity at the outlet of the variable diameter position... It can be calculated based on equation (4), which is:

[0021]

[0022] In equation (4), V represents the average particle velocity at the outlet of the variable diameter location, in m / s. f C represents the average fluid velocity in m / s. D d is the drag coefficient; o The outlet diameter at the variable diameter location is in meters (m); d p Where β is the particle diameter, in meters; βV f The velocity is the local fluid velocity, in m / s.

[0023] According to an exemplary embodiment of the present invention, the drag coefficient can be calculated based on equation (5), which is:

[0024]

[0025] The formula for calculating the particle Reynolds number Re is:

[0026]

[0027] In the formula, ρ f Fluid density, kg / m³ 3 V f The average fluid velocity is d in m / s. p Particle diameter, m; μ f ρ is the apparent viscosity of the fluid, Pa·s.

[0028] According to an exemplary embodiment of the present invention, determining the critical condition for the sealing material at the variable diameter location may include determining the critical sealing material concentration C based on a given sealing material size and injection / displacement rate. LCM-c And / or, based on the given plugging material size and concentration, determine the critical injection / displacement rate Q. c .

[0029] According to an exemplary embodiment of the present invention, the critical plugging material concentration C LCM-c It can be calculated based on equation (6), which is:

[0030]

[0031] In equation (6), C LCM-c The critical concentration of the plugging material is dimensionless. The average particle concentration at the outlet of the variable diameter position is dimensionless. The average particle velocity at the outlet of the variable diameter position is given in m / s; d o The outlet diameter at the variable diameter location is in meters (m); d pWhere is the particle diameter, in meters; Q is the displacement rate, in meters. 3 / s.

[0032] According to an exemplary embodiment of the present invention, the formula for calculating the injection displacement Q can be:

[0033]

[0034] Where Q is the injection displacement, m 3 / s;V in The velocity of the plugging grout flowing into the variable diameter location, in m / s; d i Let be the inlet diameter at the variable diameter location, in meters (m).

[0035] According to an exemplary embodiment of the present invention, the critical displacement rate Q c It can be calculated based on equation (7), which is:

[0036]

[0037] In equation (7), Q c For critical injection displacement, m 3 / s; The average particle concentration at the outlet of the variable diameter position is dimensionless. The average particle velocity at the outlet of the variable diameter position is given in m / s; d o The outlet diameter at the variable diameter location is in meters (m); d p Where C is the particle diameter, in meters; LCM The volume concentration of the plugging material flowing into the variable diameter location is dimensionless.

[0038] According to an exemplary embodiment of the present invention, determining the characteristic particle size value of the plugging material in the plugging slurry may include the following steps: S21, preparing a plugging slurry sample according to the design formula, and determining the particle size distribution of the plugging material using a sieving method; S22, calculating and plotting the cumulative particle size distribution curve of the plugging slurry, and reading the particle size corresponding to the plugging material with a cumulative volume fraction of 90% in the graph as the characteristic particle size value of the plugging material in the plugging slurry.

[0039] According to an exemplary embodiment of the present invention, the calculation of the critical value of the bridging and plugging material drill bit passability based on the prediction model may include substituting the characteristic particle size value of the plugging slurry determined in S2 to S4, the inlet and outlet diameters at the diameter change position, and the designed plugging slurry volume concentration and / or injection / displacement rate into the bridging and plugging material drill bit passability prediction model established in S1, and performing iterative calculation using numerical calculation methods to obtain the critical plugging material concentration and / or critical injection / displacement rate at the diameter change position.

[0040] According to an exemplary embodiment of the present invention, the determination of the passability of the bridging and plugging material drill bit may include calculating the critical plugging material concentration and / or critical injection displacement at the diameter change position in the drill bit assembly, obtaining their minimum values, determining whether drill bit blockage occurs under the designed plugging slurry concentration and / or injection displacement, and determining the passability of the bridging and plugging material drill bit.

[0041] According to an exemplary embodiment of the present invention, whether drill string blockage occurs at the designed injection displacement rate can be determined based on equation (8), which is:

[0042]

[0043] In equation (8), C LCM C represents the volume concentration of the sealing material flowing into the variable diameter location, dimensionless; LCM-c The critical concentration of the sealing material is dimensionless.

[0044] According to an exemplary embodiment of the present invention, whether drill string blockage occurs at the designed plugging slurry concentration can be determined based on equation (9), which is:

[0045]

[0046] In equation (9), Q c For critical injection displacement, m 3 / s.

[0047] In another aspect, the present invention provides a computer device, which may include: a processor; and a memory storing a computer program, which, when executed by the processor, implements the downhole drilling tool passability prediction method for bridging and plugging materials as described above.

[0048] In another aspect, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the downhole drilling tool passability prediction method for bridging and plugging materials as described above.

[0049] Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

[0050] (1) The bridging and plugging material drill bit passability prediction model provided by the present invention considers the comprehensive influence of factors such as plugging material concentration, size, injection rate, drill bit assembly diameter change position, base slurry density and rheology on drill bit assembly blockage, realizes quantitative prediction and judgment, and the results are more scientific, accurate and reliable, reducing the risk of drill bit blockage or plugging failure caused by insufficient accuracy leading to excessive error between the design plugging slurry formula and construction parameters.

[0051] (2) This invention is time-saving, low-cost, safe, easy to implement and highly adaptable, making it more suitable for application in well site plugging construction.

[0052] (3) This invention can determine the location with the highest risk of blockage in the drill string assembly under given conditions, quantitatively determine the critical concentration and critical displacement rate of the plugging material to safely pass through the drill string assembly, and guide the plugging grout formulation and construction design. Attached Figure Description

[0053] The above and other objects and features of the present invention will become clearer from the following description taken in conjunction with the accompanying drawings, in which:

[0054] Figure 1 A flowchart illustrating an exemplary embodiment of the present invention for predicting the passability of downhole drilling tools using bridging and plugging materials is shown.

[0055] Figure 2 The diagram shows the error analysis of the predicted critical value and the critical value of indoor experiment and numerical simulation in Example 1 of the present invention;

[0056] Figure 3 A schematic diagram of a computer device according to an exemplary embodiment of the present invention is shown.

[0057] Explanation of reference numerals in the attached figures:

[0058] 100 - Computer equipment; 101 - Memory; 102 - Processor. Detailed Implementation

[0059] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention.

[0060] To reduce the risk of downhole drill string blockage during the injection and replacement of bridging and plugging materials, this invention provides a method for predicting the downhole drill string passability of bridging and plugging materials. This method considers the maximum permissible passability of the bridging and plugging material in the downhole drill string assembly and provides a predictive model for its passability. Based on the dimensional parameters of the downhole drill string assembly used in the plugging operation, it can timely and accurately estimate the critical bridging and plugging material concentration, size, and plugging slurry injection and discharge rate for the plugging drill string. This overcomes the shortcomings of insufficient accuracy in engineers' experience-based judgment and the difficulty in conducting downhole drill string passability tests for bridging and plugging materials, providing a reliable basis for the design of bridging and plugging technology construction schemes.

[0061] Exemplary Example 1

[0062] This exemplary embodiment provides a method for predicting the passability of downhole drilling tools for bridging and plugging materials. Figure 1 The present invention illustrates the process for predicting the downhole drilling passability of bridging and plugging materials, specifically including the following steps:

[0063] S1. Establish a prediction model for the passability of drilling tools for bridging and plugging materials.

[0064] Downhole drilling tools generally function as cylindrical flow channels of uniform diameter, within which the injected bridging and plugging material flows at a set flow rate. At local locations (such as the junctions between different drill bits), there are variable-diameter channels where the flow channel diameter abruptly changes from a larger to a smaller diameter. When the amount of plugging material in the larger flow channel exceeds the maximum allowable flow capacity of the smaller flow channel, plugging will occur near the variable-diameter location. Based on this principle, a drill bit flowability prediction model for bridging and plugging material can be established to determine whether plugging occurs at the variable-diameter location.

[0065] In this embodiment, establishing a drilling tool passability prediction model for bridging and plugging materials includes the following steps:

[0066] S11. Calculate the bridging and plugging grout at a flow velocity V. in The inlet diameter of the flow into the drill string assembly is d i The outlet diameter is d o At the point of diameter change, the particle velocity N flowing into the channel with the smaller diameter change position in .

[0067] In this embodiment, it is assumed that there are n diameter-changing positions in descending order on the plugging slurry injection path in the downhole drilling tool assembly, where the inlet diameter of the m-th diameter-changing position is d. i The outlet diameter is d o Assuming the bridging and sealing material consists of uniformly sized spherical particles, and the sealing slurry flows at a velocity V... in The particle velocity N flowing into the channel with a larger diameter change position is the same as the particle velocity N flowing into the channel with a smaller diameter change position. in Calculated based on equation (1),

[0068] Equation (1) is:

[0069]

[0070] In equation (1), N in The velocity of particles flowing into the channel with a smaller diameter change position is expressed as particles / s.

[0071] d i Let be the inlet diameter at the variable diameter location, in meters (m).

[0072] V in The velocity of the sealing grout flowing into the variable diameter location, in m / s;

[0073] C LCM The volume concentration of the plugging material flowing into the variable diameter location is dimensionless.

[0074] dp denoted as particle diameter, in meters (m).

[0075] S12. Calculate the maximum particle discharge velocity N at the outlet of the variable diameter position. out，max .

[0076] In this embodiment, the maximum particle discharge velocity N at the outlet can be obtained by integrating the fluid velocity and volume concentration at the outlet of the variable diameter location over the outlet area. out，max (Number of particles per unit of time):

[0077]

[0078] In the formula, r is the distance from a point to the center of the exit, and V exit (r) represents the outlet fluid velocity profile, C exit (r) represents the outlet particle volume concentration profile.

[0079] The above formula can be simplified to:

[0080]

[0081] The particle discharge volume concentration in the piston flow model is integrated over the above equation. In piston flow, C exit V is constant throughout the entire outlet. exit Only at the edge of the exit (C) exit Only when N = 0 is there a significant deviation from the center line. Therefore, N out，max It can be well approximated by equation (2):

[0082]

[0083] In equation (2), N out，max The maximum particle discharge velocity at the outlet of the variable diameter position, particles / s;

[0084] The average particle concentration at the outlet of the variable diameter position is dimensionless.

[0085] The average particle velocity at the outlet of the variable diameter position is in m / s;

[0086] d o Let be the outlet diameter at the variable diameter location, in meters (m).

[0087] d p denoted as particle diameter, in meters (m).

[0088] S13. Calculate the average particle concentration at the outlet of the variable diameter position based on classical experimental data.

[0089] In this embodiment, based on the empirical formula for particle discharge concentration with different combinations of particle and opening sizes, when the opening is reduced to near the particle size, the particle volume concentration at the opening centerline tends to be 0.48, close to the assumed particle size from a distance equal to d. o / d p The height obtained by passing through the openings one after another is 0.52. As the openings gradually increase in size, the particle volume concentration at the center line of the openings tends to be 0.83, which is very close to the critical particle volume concentration of 0.84 for the transition from a blocked state to a flow dynamic in isotropic compression. For piston flow, C exit The average particle concentration at the outlet is constant throughout the opening; therefore, assuming the average particle concentration at the outlet is equal to the particle concentration at the centerline, the average particle concentration at the outlet is... Calculated based on equation (3),

[0090] Equation (3) is:

[0091]

[0092] In equation (3), The average particle concentration at the outlet of the variable diameter position is dimensionless.

[0093] e is a natural constant;

[0094] d o Let be the outlet diameter at the variable diameter location, in meters (m).

[0095] d p denoted as particle diameter, in meters (m).

[0096] S14. Calculate the average particle velocity at the outlet of the variable diameter position based on the Free Falling Arch theory.

[0097] In this embodiment, assuming that the Free Falling Arch (FFA) theory still holds in fluid-driven flows, and that particles are freely dragged by the flowing fluid rather than falling freely under gravity, then a particle dragged by a fluid satisfies the following condition in its direction of motion x:

[0098]

[0099] In the formula, a p It is the acceleration of the particle, V p Where x is the velocity of the particle, and x is the direction of fluid flow. D It is the drag coefficient, V f It is the average fluid velocity, βV f It is the local fluid velocity, which has certain characteristics at the point of change of diameter.

[0100]

[0101] Use boundary conditions (V) p =0, x=0; x = d o Solving the above equations will yield the particle exit velocity. Expression (4) is:

[0102]

[0103] In equation (4), The average particle velocity at the outlet of the variable diameter position is in m / s;

[0104] V f The average fluid velocity is given in m / s.

[0105] C D This is the drag coefficient;

[0106] d o Let be the outlet diameter at the variable diameter location, in meters (m).

[0107] d p Where is the particle diameter, in meters (m);

[0108] βV f The velocity is the local fluid velocity, in m / s.

[0109] In this embodiment, the drag coefficient is calculated based on equation (5), which is:

[0110]

[0111] The formula for calculating the particle Reynolds number Re is:

[0112]

[0113] In the formula, ρ f Fluid density, kg / m³ 3 ;

[0114] V f The average fluid velocity is given in m / s.

[0115] d p Where is the particle diameter, in meters (m);

[0116] μ f ρ is the apparent viscosity of the fluid, Pa·s.

[0117] S15. Based on the condition of no blockage at the diameter change position: N in <N out,max Determine the critical conditions for the sealing material to pass through the variable diameter location.

[0118] When the velocity of the particles flowing into the smaller channel at the diameter change position is less than the maximum particle discharge velocity, the diameter change position will not be blocked, and the sealing material will pass through the diameter change position smoothly.

[0119] In this embodiment, by comparing equation (1) and equation (2): N in <N out,max This allows us to determine the critical conditions for the sealing material to pass through the variable diameter location.

[0120] In this embodiment, determining the critical condition for the sealing material to pass through the change-of-diameter location includes determining the critical sealing material concentration C based on the given sealing material size and injection / displacement rate. LCM-c Based on the given size and concentration of the plugging material, determine the critical injection / displacement rate Q. c .

[0121] For a given plugging material size and injection / displacement rate, the critical plugging material concentration C LCM-c Calculated based on equation (6),

[0122] Equation (6) is:

[0123]

[0124] In equation (6), C LCM-c The critical concentration of the plugging material is dimensionless.

[0125] The average particle concentration at the outlet of the variable diameter position is dimensionless.

[0126] The average particle velocity at the outlet of the variable diameter position is in m / s;

[0127] d o Let be the outlet diameter at the variable diameter location, in meters (m).

[0128] d p Where is the particle diameter, in meters (m);

[0129] Q represents the displacement, m 3 / s.

[0130] Furthermore, the formula for calculating the displacement Q is:

[0131]

[0132] Where Q is the injection displacement, m 3 / s;

[0133] V in The velocity of the sealing grout flowing into the variable diameter location, in m / s;

[0134] d i Let be the inlet diameter at the variable diameter location, in meters (m).

[0135] For a given plugging material size and concentration, the critical displacement rate Q c Calculated based on equation (7),

[0136] Equation (7) is:

[0137]

[0138] In equation (7), Q c For critical injection displacement, m 3 / s;

[0139] The average particle concentration at the outlet of the variable diameter position is dimensionless.

[0140] The average particle velocity at the outlet of the variable diameter position is in m / s;

[0141] d o Let be the outlet diameter at the variable diameter location, in meters (m).

[0142] d p Where is the particle diameter, in meters (m);

[0143] C LCM The volume concentration of the plugging material flowing into the variable diameter location is dimensionless.

[0144] S2. Determine the characteristic particle size value of the sealing material in the sealing grout.

[0145] For a homogeneous particulate system, d p It is the diameter of a single particle. For a particle system with a certain particle size distribution, d p It is a particle size range. Studies have found that clogging in polydisperse particle systems is mainly caused by large particles (d... p ≥d 90 The decision is based on the fact that the bridging structures causing blockages are primarily composed of these large particles. The blockage probability of particle systems with a wide particle size distribution correlates poorly with the volume average diameter but strongly with d0 / d 90 The correlation is very good.

[0146] For particle systems with different particle size distributions, d 90 If the particle systems are the same, the probability of blockage at the same opening is the same, and their critical and absolute blockage d0 / d 90 The same applies to both polydisperse and homogeneous particle systems. 90 If they are the same, then the critical and absolute blocking d0 / d 90 They are basically the same. Therefore, d 90 It can be used as a characteristic particle size of a particle system with particle size distribution for predicting the passability of bridging and plugging materials in drilling tools.

[0147] In this embodiment, determining the characteristic particle size value of the sealing slurry includes the following steps:

[0148] S21. Prepare a sample of the sealing slurry according to the design formula, and determine the particle size distribution of the sealing material by sieving method.

[0149] S22. Calculate and plot the cumulative particle size distribution curve of the plugging formula using the measured particle size distribution data. The particle size corresponding to the plugging material with a cumulative volume fraction of 90% in the graph is the characteristic particle size value d of the plugging slurry. 90 .

[0150] S3. Determine the number of variable diameter locations and inlet / outlet diameters of the downhole drilling tool assembly.

[0151] In this embodiment, based on the current downhole drill string assembly, the total number n of diameter-changing locations, including drill string connections, water inlets, screws, MWD (Measurement While Drilling), LWD (Log While Drilling), directional tools, and check valves, is determined. The inlet diameter d of each diameter-changing location is determined by consulting the drill string manual for each location. i and outlet diameter d o .

[0152] S4. Measure the density and apparent viscosity of the plugging slurry base.

[0153] In this embodiment, a sample of the plugging slurry is prepared, and the density ρ of the base slurry is measured using a drilling fluid density meter. f The apparent viscosity μ of the base slurry was measured using a six-speed rotational viscometer. f Of course, the measuring instruments are not limited to these. Other similar instruments can be used to measure the density of the base slurry, and similar instruments such as an eight-speed rotational viscometer and a stepless speed-adjustable rotational viscometer can be used to measure the apparent viscosity of the base slurry.

[0154] S5. Calculate the critical value of the drilling tool's passability for bridging and plugging materials based on the prediction model.

[0155] In this embodiment, the critical plugging material concentration C at the m-th diameter change position is calculated according to steps S1 to S4. LCM-cm and critical displacement Q cm .

[0156] The characteristic particle size values ​​of the plugging material, the inlet and outlet diameters at the diameter change position, the drag coefficient, and the designed plugging slurry volume concentration and injection / displacement rate determined in S2 to S4 are substituted into the bridging plugging material drill bit passability prediction model established in S1. Numerical calculation methods are used for iterative calculation to obtain the critical plugging material concentration and / or critical injection / displacement rate at the diameter change position.

[0157] S6. Determine the drilling passability of the bridging and plugging material.

[0158] In this embodiment, the critical plugging material concentration C at the m diameter change locations calculated in step S5 is determined. LCM-c and critical displacement Q c The minimum value. Use equations (8) and (9) to determine whether drill bit blockage occurs under the designed plugging grout concentration and injection / displacement rate.

[0159] In this embodiment, whether drill string blockage occurs at the designed injection displacement rate is determined based on equation (8).

[0160] Equation (8) is:

[0161]

[0162] In equation (8), C LCM The volume concentration of the plugging material flowing into the variable diameter location is dimensionless.

[0163] C LCM-c The critical concentration of the sealing material is dimensionless.

[0164] C LCM To prevent clogging, the concentration of the sealing material must be less than the minimum critical concentration at all diameter changes. LCM If the concentration of the sealing material exceeds the critical level at any point where the diameter changes, a blockage will occur at that point.

[0165] In this embodiment, whether drill string blockage occurs at the designed plugging slurry concentration is determined based on equation (9).

[0166] Equation (9) is:

[0167]

[0168] In equation (9), Q c For critical injection displacement, m 3 / s.

[0169] Q c To prevent clogging, the displacement must be less than the minimum critical displacement at all diameter change positions. c If the displacement exceeds the critical displacement at any change-of-diameter position, a blockage will occur at that position.

[0170] Exemplary Example 2

[0171] This exemplary embodiment provides a method for predicting the passability of downhole drilling tools using bridging and plugging materials. The method is essentially the same as the method for predicting the passability of downhole drilling tools using bridging and plugging materials described in Exemplary Embodiment 1, except that:

[0172] In this embodiment, the critical condition for determining the plugging material at the change-of-diameter location in step S15 includes determining the critical plugging material concentration C based on the given plugging material size and injection / displacement rate. LCM-c Furthermore, in step S6, determining the drill bit passability of the bridging and plugging material only requires calculating the critical plugging material concentration C at the m-th diameter change position. LCM-c The minimum value is compared with the design value to determine whether drill string blockage occurs under the designed injection displacement rate.

[0173] S15. Based on the condition of no blockage at the diameter change position: N in <N out,max Determine the critical conditions for the sealing material to pass through the variable diameter location.

[0174] In this embodiment, for a given plugging material size and injection / displacement rate, the critical plugging material concentration C is... LCM-c Calculated based on equation (6),

[0175] Equation (6) is:

[0176]

[0177] In equation (6), C LCM-c The critical concentration of the plugging material is dimensionless.

[0178] The average particle concentration at the outlet of the variable diameter position is dimensionless.

[0179] The average particle velocity at the outlet of the variable diameter position is in m / s;

[0180] d o Let be the outlet diameter at the variable diameter location, in meters (m).

[0181] d p Where is the particle diameter, in meters (m);

[0182] Q represents the displacement, m 3 / s.

[0183] S6. Determine the drilling passability of the bridging and plugging material.

[0184] In this embodiment, whether drill string blockage occurs at the designed injection displacement rate is determined based on equation (8).

[0185] Equation (8) is:

[0186]

[0187] In equation (8), C LCM The volume concentration of the plugging material flowing into the variable diameter location is dimensionless.

[0188] CLCM-c The critical concentration of the sealing material is dimensionless.

[0189] C LCM To prevent clogging, the concentration of the sealing material must be less than the minimum critical concentration at all diameter changes. LCM If the concentration of the sealing material exceeds the critical level at any point where the diameter changes, a blockage will occur at that point.

[0190] Exemplary Example 3

[0191] This exemplary embodiment provides a method for predicting the passability of downhole drilling tools using bridging and plugging materials. The method is essentially the same as the method for predicting the passability of downhole drilling tools using bridging and plugging materials described in Exemplary Embodiment 1, except that:

[0192] In this embodiment, the critical condition for determining the location of the plugging material at the change-of-diameter point in step S15 includes determining the critical injection / displacement rate Q based on the given plugging material size and concentration. c Furthermore, in step S6, determining the drill bit passability of the bridging and plugging material only requires calculating the critical displacement rate Q at the m-th diameter change position. c The minimum value is compared with the design value to determine whether drill bit blockage occurs at the designed plugging grout concentration.

[0193] S15. Based on the condition of no blockage at the diameter change position: N in <N out,max Determine the critical conditions for the sealing material to pass through the variable diameter location.

[0194] In this embodiment, for a given plugging material size and concentration, the critical displacement rate Q is... c Calculated based on equation (7),

[0195] Equation (7) is:

[0196]

[0197] In equation (7), Q c For critical injection displacement, m 3 / s;

[0198] The average particle concentration at the outlet of the variable diameter position is dimensionless.

[0199] The average particle velocity at the outlet of the variable diameter position is in m / s;

[0200] d o Let be the outlet diameter at the variable diameter location, in meters (m).

[0201] d p Where is the particle diameter, in meters (m);

[0202] C LCM The volume concentration of the plugging material flowing into the variable diameter location is dimensionless.

[0203] S6. Determine the drilling passability of the bridging and plugging material.

[0204] In this embodiment, whether drill string blockage occurs at the designed plugging slurry concentration is determined based on equation (9).

[0205] Equation (9) is:

[0206]

[0207] In equation (9), Q c For critical injection displacement, m 3 / s.

[0208] Q c To prevent clogging, the displacement must be less than the minimum critical displacement at all diameter change positions. c If the displacement exceeds the critical displacement at any change-of-diameter position, a blockage will occur at that position.

[0209] To better understand exemplary embodiments of the present invention, further explanation is provided below with reference to specific examples.

[0210] Example 1

[0211] The method for predicting the passability of downhole drilling tools using bridging and plugging materials according to the present invention is as follows: Figure 1 The process shown uses relevant numerical simulations and indoor experimental data to predict the downhole drilling performance of bridging and plugging materials. The specific implementation steps are as follows:

[0212] Step 1: Prepare the sealing slurry according to the design formula, measure the particle size distribution of the sealing material using the sieving method, plot the cumulative particle size distribution curve of the sealing formula, and obtain the characteristic particle size value d. 90 As shown in Table 1 below.

[0213] Table 1

[0214]

[0215] Step 2: Determine the number of diameter change positions n and the inlet and outlet diameters d of the current drill string assembly. i d o In this example, the variable diameter position is 1 in a single indoor experiment or numerical simulation, and the inlet and outlet diameters are d. i d o As shown in Table 2 below.

[0216] Table 2

[0217]

[0218] Step 3: Determine the density ρ of the sealing grout base. f and apparent viscosity μ f Take samples of the plugging slurry to prepare the base slurry, and measure the density ρ using a drilling fluid density meter. f Apparent viscosity μ was measured using a six-speed rotational viscometer. f The measurement results are shown in Table 3 below.

[0219] Table 3

[0220] slurry rheological parameters Indoor Experiment 1 Numerical Simulation 1 Numerical Simulation II <![CDATA[ρ f ,kg / m 3 ]]> 1070 1000 1000 <![CDATA[μ f ,Pa·s]]> 0.003 0.01 0.001

[0221] Step 4: Design the grout injection displacement volume Q. The injection displacement volumes designed by indoor experiments and numerical simulations are shown in Table 4 below.

[0222] Table 4

[0223] slurry rheological parameters Indoor Experiment 1 Numerical Simulation 1 Numerical Simulation II <![CDATA[Q,m 3 / s]]> <![CDATA[1.459×10 -3 ]]> <![CDATA[2.7~5.85×10 -6 ]]> <![CDATA[1.0368×10 -5 ]]>

[0224] Step 5: Using the data from steps 1 to 4, substitute them into equations (1) to (5) to obtain the critical plugging material concentration C at each diameter change location. LCM-c The critical values ​​predicted by this invention are compared with those from indoor experiments and numerical simulations, for example... Figure 2 As shown.

[0225]

[0226]

[0227]

[0228]

[0229]

[0230] Step 6: Determine the minimum critical plugging material concentration (min) for the current drill string assembly. LCM-c Since the number of diameter change locations is 1, the critical plugging material concentration C calculated in step 5 is... LCM-c It is also the minimum value.

[0231] Step 7: Determine if the design value is less than the minimum critical value. For the sealing material d in Indoor Experiment 1... 90 =0.0191m, d i =0.1016m, d o In the case of 0.06668m, arbitrarily choosing a design plugging grout concentration of 30%, the min(C) calculated in step 6 is... LCM-cThe design value was 35.39%, while the experimental value was 35.47%, showing a very close match between the predicted and experimental values. Since the design value was lower than the predicted critical value, the plugging material could safely pass through the drill string assembly at this concentration.

[0232] The method for predicting the passability of bridging and plugging materials in downhole drilling tools according to the present invention can be programmed into a computer program and the corresponding program code or instructions can be stored in a computer-readable storage medium. When the program code or instructions are executed by a processor, the processor performs the above-described method for predicting the passability of bridging and plugging materials in downhole drilling tools. The processor and memory can be included in a computer device.

[0233] Exemplary Example 4

[0234] An exemplary embodiment of another aspect of the present invention also provides a computer-readable storage medium storing a computer program. The computer-readable storage medium stores a computer program that, when executed by a processor, causes the processor to execute the method for predicting the bridging plugging material downhole drilling tool accessibility according to the present invention. The computer-readable recording medium is any data storage device capable of storing data readable by a computer system. Examples of computer-readable recording media include: read-only memory, random access memory, read-only optical disk, magnetic tape, floppy disk, optical data storage device, and carrier waves (such as data transmission via the Internet through wired or wireless transmission paths).

[0235] Exemplary Example 5

[0236] An exemplary embodiment of another aspect of the present invention also provides a computer device.

[0237] In this embodiment, as Figure 3 As shown, the computer device 100 includes a memory 101 and a processor 102. The memory 101 stores computer programs. The computer programs are executed by the processor 102, causing the processor 102 to execute the computer program of the method for predicting the passability of bridging plugging materials in downhole drilling tools according to the present invention.

[0238] In summary, this invention can quickly and accurately determine the drill string permeability of plugging materials based on the current downhole drill string assembly, plugging formula design, and construction parameters. This provides a more accurate basis for designing plugging formulas and determining plugging construction parameters, reduces the risk of drill string blockage during the plugging process, and thus improves the safety and success rate of plugging construction.

[0239] Although the invention has been described above in conjunction with exemplary embodiments, those skilled in the art will understand that various modifications and changes can be made to the exemplary embodiments of the invention without departing from the spirit and scope defined by the claims.

Claims

1. A method for predicting the passability of downhole drilling tools for bridging and plugging materials, characterized in that, The method includes the following steps: S1. Establish a prediction model for the passability of drilling tools for bridging and plugging materials; S2. Determine the characteristic particle size value of the plugging material in the plugging grout; S3. Determine the number of variable diameter locations and inlet / outlet diameters for downhole drilling tool assemblies; S4. Measure the density and apparent viscosity of the plugging slurry base; S5. Calculate the critical value for the drilling tool's passability of the bridging and plugging material based on the prediction model; and S6. Determine the drilling passability of the bridging and plugging material; The establishment of the drilling tool passability prediction model for bridging and plugging materials includes the following steps: S11. Calculate the bridging and sealing grout at the flow rate. V in The inlet diameter of the inflow into the drill string assembly is d i The outlet diameter is d o At the point of diameter change, the particle velocity flowing into the channel with the smaller diameter change position. N in ; S12. Calculate the maximum particle discharge velocity at the outlet of the variable diameter position. N out，max ; S13. Calculate the average particle concentration at the outlet of the variable diameter position based on classical experimental data. ; S14. Calculate the average particle velocity at the outlet of the variable diameter position based on the Free Falling Arch theory. ;as well as S15. Based on the condition of no blockage at the diameter change position: Determine the critical conditions for the sealing material to pass through the variable diameter location; The critical value for the passability of the bridging and plugging material drill bit calculated according to the prediction model includes substituting the characteristic particle size value of the plugging slurry determined in S2 to S4, the inlet and outlet diameters at the diameter change position, and the designed plugging slurry volume concentration and / or injection and displacement rate into the bridging and plugging material drill bit passability prediction model established in S1, and using numerical calculation methods to perform iterative calculations to obtain the critical plugging material concentration and / or critical injection and displacement rate at the diameter change position. The determination of the passability of the bridging and plugging material drill bit includes calculating the critical plugging material concentration and / or critical injection and displacement rate at the diameter change position in the drill bit assembly, obtaining their minimum values, determining whether drill bit blockage occurs under the designed plugging slurry volume concentration and / or injection and displacement rate, and determining the passability of the bridging and plugging material drill bit. The particle velocity flowing into the channel with the smaller diameter change position N in Calculated based on equation (1), Equation (1) is: In equation (1), N in The velocity of particles flowing into the channel with a smaller diameter change position is expressed as particles / s. d i Let be the inlet diameter at the variable diameter location, in meters (m). V in The velocity of the sealing grout flowing into the variable diameter location, in m / s; C LCM The volume concentration of the plugging material flowing into the variable diameter location is dimensionless. d p Where is the particle diameter, in meters (m); The maximum particle discharge velocity at the outlet of the variable diameter position N out，max Calculated based on equation (2); Equation (2) is: In equation (2), N out，max The maximum particle discharge velocity at the outlet of the variable diameter position, particles / s; The average particle concentration at the outlet of the variable diameter position is dimensionless. The average particle velocity at the outlet of the variable diameter position is in m / s; d o Let be the outlet diameter at the variable diameter location, in meters (m). d p Where is the particle diameter, in meters (m); The critical condition for determining the location of the plugging material change includes determining the critical plugging material concentration based on the given plugging material size and injection / displacement rate. C LCM-c And / or, based on the given plugging material size and concentration, determine the critical displacement rate. Q c ; The critical concentration of the plugging material C LCM-c Calculated based on equation (6), Equation (6) is: In equation (6), C LCM-c The critical concentration of the plugging material is dimensionless. The average particle concentration at the outlet of the variable diameter position is dimensionless. The average particle velocity at the outlet of the variable diameter position is in m / s; d o Let be the outlet diameter at the variable diameter location, in meters (m). d p Where is the particle diameter, in meters (m); Q For displacement, m 3 / s.

2. The method for predicting the passability of downhole drilling tools for bridging and plugging materials according to claim 1, characterized in that, The average particle concentration at the outlet of the variable diameter position Calculated based on equation (3), Equation (3) is: In equation (3), The average particle concentration at the outlet of the variable diameter position is dimensionless. e It is a natural constant; d o Let be the outlet diameter at the variable diameter location, in meters (m). d p denoted as particle diameter, in meters (m).

3. The method for predicting the passability of downhole drilling tools for bridging and plugging materials according to claim 1, characterized in that, Average particle velocity at the outlet of the variable diameter position Calculated based on equation (4), Equation (4) is: In equation (4), The average particle velocity at the outlet of the variable diameter position is in m / s; V f The average fluid velocity is given in m / s. C D This is the drag coefficient; d o Let be the outlet diameter at the variable diameter location, in meters (m). d p Where is the particle diameter, in meters (m); βV f The velocity is the local fluid velocity, in m / s.

4. The method for predicting the passability of downhole drilling tools for bridging and plugging materials according to claim 3, characterized in that, The drag coefficient is calculated based on equation (5). Equation (5) is: The formula for calculating the particle Reynolds number Re is: In the formula, ρ f Fluid density, kg / m³ 3 ; V f The average fluid velocity is given in m / s. d p Where is the particle diameter, in meters (m); μ f ρ is the apparent viscosity of the fluid, Pa·s.

5. The method for predicting the passability of downhole drilling tools for bridging and plugging materials according to claim 1, characterized in that, The displacement Q The formula for calculation is: in, Q For displacement, m 3 / s; V in The velocity of the sealing grout flowing into the variable diameter location, in m / s; d i Let be the inlet diameter at the variable diameter location, in meters (m).

6. The method for predicting the passability of downhole drilling tools for bridging and plugging materials according to claim 1, characterized in that, The critical displacement rate Q c Calculated based on equation (7), Equation (7) is: In equation (7), Q c For critical injection displacement, m 3 / s; The average particle concentration at the outlet of the variable diameter position is dimensionless. The average particle velocity at the outlet of the variable diameter position is in m / s; d o Let be the outlet diameter at the variable diameter location, in meters (m). d p Where is the particle diameter, in meters (m); C LCM The volume concentration of the plugging material flowing into the variable diameter location is dimensionless.

7. The method for predicting the passability of downhole drilling tools for bridging and plugging materials according to claim 1, characterized in that, The determination of the characteristic particle size value of the sealing slurry includes the following steps: S21. Prepare sealing slurry samples according to the design formula, and determine the particle size distribution of the sealing material using the sieving method; and S22. Calculate and plot the cumulative particle size distribution curve of the plugging slurry. The particle size corresponding to the plugging material with a cumulative volume fraction of 90% in the figure is the characteristic particle size value of the plugging material in the plugging slurry.

8. The method for predicting the passability of downhole drilling tools for bridging and plugging materials according to claim 1, characterized in that, Whether drill string blockage occurs under the designed injection displacement rate is determined based on equation (8). Equation (8) is: In equation (8), C LCM The volume concentration of the plugging material flowing into the variable diameter location is dimensionless. C LCM-c The critical concentration of the sealing material is dimensionless.

9. The method for predicting the passability of downhole drilling tools for bridging and plugging materials according to claim 1, characterized in that, Whether drill string blockage occurs at the designed plugging slurry concentration is determined based on equation (9). Equation (9) is: In equation (9), Q c For critical injection displacement, m 3 / s.

10. A computer device, characterized in that, The computer device includes: processor; and The memory stores a computer program that, when executed by a processor, implements the method for predicting the passability of downhole drilling tools for bridging and plugging materials as described in any one of claims 1 to 9.

11. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by a processor, it implements the method for predicting the passability of downhole drilling tools for bridging and plugging materials as described in any one of claims 1 to 9.

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