Power well-killing construction parameter chart of blowout well and construction method of power well-killing construction parameter chart

Abstract

The invention discloses a power well killing construction parameter chart of a blowout well and a construction method of the power well killing construction parameter chart. The construction method comprises the following steps of S1, obtaining field data of a target well; s2, establishing a well killing calculation model capable of simulating well killing processes under different well killing parameters; s3, establishing a critical well killing parameter optimization objective function; s4, establishing a genetic optimization algorithm model; s5, the well killing process is simulated through the well killing calculation model, and the critical well killing parameter optimization objective function and the genetic optimization algorithm model are combined for optimization calculation to obtain multiple sets of critical well killing fluid density and critical well killing fluid displacement; and S6, a density and displacement chart is drawn through the multiple sets of critical well killing fluid densities and critical well killing fluid displacements, the density and displacement parameter feasible area is obtained in combination with the density and displacement limiting range of actual conditions, and therefore the empty jet well dynamic well killing construction parameter chart is obtained. According to the method, the empty-jet well dynamic well killing construction parameter chart can be constructed, and a new thought is provided for empty-jet well dynamic well killing parameter design.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of well control of oil drilling, and particularly relates to a blowout well power well killing construction parameter chart and a construction method thereof. BACKGROUND

[0002] With the increasing intensity of oil and gas field development in China, the development range is continuously expanded, the development environment is more and more harsh, the formation conditions are more and more complex, and overflow occurs more frequently in the drilling process. If overflow cannot be discovered and controlled in time, it may further develop into well kick or even blowout, causing serious safety accidents. Blowout accidents are often difficult to avoid, but how to quickly, safely and efficiently dispose of blowout is the key to well control operation and ensures safe and efficient development of oil and gas.

[0003] A blowout well refers to a well in which there is no drilling fluid in the wellbore, and pure gas flows in the wellbore. Blowout well power well killing is often used for well killing operation because of its simple operation, multiple applicable working conditions and other advantages. The high pressure of the formation when blowout makes the wellbore and wellhead equipment after blowout may be damaged to different degrees, reducing the wellbore integrity and leading to a decrease in the wellbore pressure-bearing capacity during well killing. For the traditional power well killing process, referred to as "Process 1" (as shown in Figure 1 ), a suitable well killing fluid density and displacement combination can complete well killing, and it is applicable to working conditions with good wellbore integrity; for working conditions with low wellbore integrity, a light weight well killing fluid is generally first injected to balance the bottom hole pressure with the formation pressure, then air is continuously circulated, and finally a heavy weight well killing fluid is injected to complete well killing, referred to as "Process 2" (as shown in Figure 2 ); for working conditions with extremely low wellbore integrity, referred to as "Process 3" (as shown in Figure 3 ), a light weight well killing fluid is generally first injected to establish a certain continuous liquid phase in the wellbore, thereby minimizing the formation gas production, and then a heavy weight well killing fluid is injected to complete well killing. For the above three well killing processes, there is currently a lack of well killing parameter design method that can guide actual operation. SUMMARY

[0004] In view of the above problems, the present application aims to provide a blowout well power well killing construction parameter chart and a construction method thereof.

[0005] The technical scheme of the present application is as follows: On the one hand, a construction method of a blowout well power well killing construction parameter chart is provided, comprising the following steps: S1: obtaining field data of a target well; S2: establishing a well killing calculation model capable of simulating well killing processes under different well killing parameters; S3: taking well killing fluid density and well killing fluid displacement as optimization parameters, taking that the optimization parameters can just successfully complete well killing as an optimization target, and establishing a critical well killing parameter optimization target function. S4: a genetic optimization algorithm model is established, and an individual fitness value of the genetic optimization algorithm model is calculated in combination with the critical well killing parameter optimization objective function; S5: a well killing process is simulated by using the well killing calculation model, and a plurality of sets of critical well killing fluid density and critical well killing fluid displacement are obtained in combination with the critical well killing parameter optimization objective function and the genetic optimization algorithm model optimization calculation; S6: a density displacement chart is drawn through the plurality of sets of critical well killing fluid density and critical well killing fluid displacement, and a parameter feasible region of density displacement is obtained in combination with a limitation range of density and displacement under a real condition, so as to obtain the blowout well dynamic well killing construction parameter chart.

[0006] Preferably, in step S1, the field data includes wellbore structure, drilling tool assembly, pipe wall absolute roughness, wellhead gas production, wellhead temperature, geothermal gradient, well killing fluid density, well killing fluid displacement, and maximum allowable casing pressure.

[0007] Preferably, in step S2, the well killing calculation model includes an annular gas-liquid two-phase flow model and boundary conditions, the annular gas-liquid two-phase flow model is established based on a gas mass conservation equation, a liquid mass conservation equation, and a gas-liquid two-phase momentum conservation equation in combination with a drift flow model; and the pressure boundary of the boundary conditions is established according to a pressure relationship of the wellbore in the well killing process.

[0008] Preferably, the gas mass conservation equation is: (1) In the formula, A is an annular cross-sectional area, m 2 ; f g is a gas phase volume fraction, dimensionless; p g is a gas phase density, kg / m 3 ; t is a time step, ; v g is a gas phase real velocity, m / s; and x is a space step, m. The liquid mass conservation equation is: (2) In the formula, f l is a well killing fluid volume fraction, dimensionless; p l is a well killing fluid density, kg / cm 3 ; and v l is a well killing fluid real velocity, m / s. The gas-liquid two-phase momentum conservation equation is: (3) In the formula, P is pressure, MPa; p m is a mixed phase density, kg / cm3 ; g is the acceleration of gravity, m / s 2 ; θ is the deviation angle, rad; F m is the miscible friction, MPa; The real gas velocity in the drift-flux model is calculated by the following equation: (4) wherein: Co is the gas distribution coefficient; v m is the gas-liquid mixing velocity, m / s; v d is the drift velocity, m / s.

[0009] As a preference, the gas distribution coefficient is calculated by the following equation: (5) wherein: B is the cross-sectional parameter, dimensionless; γ is the cross-sectional parameter limiting term between 0 and 1, dimensionless; The gas-liquid mixing velocity is calculated by the following equation: (6) The drift velocity is calculated by the following equation: (7) wherein: K(f g ) is the critical Kutateladze number; v c is the characteristic velocity, m / s; m( ) represents the effect of the deviation angle on the drift velocity.

[0010] As a preference, for process one which is suitable for good wellbore integrity conditions, the boundary conditions include a first pressure relationship in the annulus during killing and a second pressure relationship in the drill pipe; For process two which is suitable for lower wellbore integrity conditions, the boundary conditions include a third pressure relationship in the annulus and a fourth pressure relationship in the drill pipe during injection of light kill fluid, a fifth pressure relationship in the annulus after venting and injection of heavy kill fluid, and a sixth pressure relationship in the drill pipe before the heavy kill fluid enters the annulus; and the third pressure relationship is the same as the first pressure relationship, and the fourth pressure relationship is the same as the second pressure relationship; For process three which is suitable for extremely low wellbore integrity conditions, the boundary conditions include a seventh pressure relationship in the annulus and an eighth pressure relationship in the drill pipe during injection of light kill fluid, a ninth pressure relationship in the annulus during injection of heavy kill fluid, and a tenth pressure relationship in the drill pipe before the heavy kill fluid enters the annulus; and the seventh pressure relationship is the same as the first pressure relationship, the eighth pressure relationship is the same as the second pressure relationship, and the tenth pressure relationship is the same as the sixth pressure relationship.

[0011] As a preference, the first pressure relationship is: (8) In the formula: P b P represents the bottom hole pressure, in MPa. a For casing pressure, MPa; P gf Gas circulation friction, MPa; P gh P is the air column pressure, in MPa; mf The circulating friction of the gas-liquid mixture is measured in MPa; P mh The static pressure of the gas-liquid mixture is MPa. The second pressure relationship is as follows: (9) In the formula: P t Pump pressure, MPa; P lf The frictional resistance of the kill fluid circulation, MPa; P lh P is the liquid column pressure, in MPa; bit The drill bit pressure drop is measured in MPa. The fifth pressure relationship is: (10) In the formula: P Lf To increase the friction of the kill fluid circulation, MPa; P Lh To increase the pressure of the kill fluid column, MPa; The pressure relationship six is ​​as follows: (11) The pressure relationship nine is as follows: (12) In the formula: P Mf The circulating friction of the gas and weighted kill fluid mixture, MPa; P Mh The static pressure of the mixture of gas and weighted well-killing fluid is MPa.

[0012] Preferably, in step S3, for process one applicable to wellbore integrity conditions, the objective function for optimizing the critical well control parameters includes: (13) (14) For Process 2, which is applicable to conditions with low wellbore integrity, the objective function for optimizing the critical well control parameters includes: (15) (16) For Process 3, which is applicable to conditions with extremely low wellbore integrity, the objective function for optimizing the critical well-killing parameters includes: (17) (18) In the formula: P aerror The error between the casing pressure and atmospheric pressure is expressed in MPa; Q k Mud represents the kill fluid displacement, in L / s. k To optimize the density of the kill fluid, kg / m 3 ;P p Formation pressure, MPa; Time error Time represents the time node error, which is dimensionless; Time represents the time node required for well control, which is dimensionless; Time0 represents the total time node from the bottom of the well to the wellhead, which is dimensionless.

[0013] Preferably, in step S4, the individual fitness value of the genetic optimization algorithm model is calculated using the following formula: (19) Where: Fitness i Let be the individual fitness value of individual i, which is dimensionless; e is the natural base, which is dimensionless; w1 and w2 are both weighting coefficients, and their sum is 1. The total fitness of the current i individuals is represented as: (20) Where: C_Fitness i for i The total fitness of an individual, dimensionless; C_Fitness i-1 for i -1 is the total fitness of an individual, dimensionless; The average fitness of a population is expressed as: (twenty one) In the formula: Ave_Fitness N denoted as the average fitness of the population, dimensionless; N is the number of individuals in the population, dimensionless.

[0014] On the other hand, a power kill construction parameter chart for blowout wells is also provided, which is constructed using the construction method for power kill construction parameter charts for blowout wells described in any one of the above-mentioned methods.

[0015] The beneficial effects of this invention are: This invention can construct a chart of dynamic well control parameters for blowout wells. This chart can intuitively reflect the reasonable selection range of well control parameters and provide new ideas for the design of dynamic well control parameters for blowout wells. Attached Figure Description

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0017] Figure 1 Figure 1 is a schematic diagram of critical killing of process one; Figure 2 Figure 2 is a schematic diagram of critical killing of process two; Figure 3 Figure 3 is a schematic diagram of critical killing of process three; Figure 4 Figure 4 is a schematic diagram of gene crossing; Figure 5 Figure 5 is a schematic diagram of gene mutation; Figure 6 Figure 6 is a schematic diagram of genetic optimization algorithm calculation process; Figure 7 Figure 7 is a schematic diagram of critical killing parameter convergence process of process one in a specific embodiment; Figure 8 Figure 8 is a schematic diagram of critical killing parameter convergence process of process two in a specific embodiment; Figure 9 Figure 9 is a schematic diagram of critical killing parameter convergence process of process three in a specific embodiment; Figure 10 Figure 10 is a construction parameter chart of process one in a specific embodiment; Figure 11 Figure 11 is a construction parameter chart of process two in a specific embodiment; Figure 12 Figure 12 is a construction parameter chart of process three in a specific embodiment. DETAILED DESCRIPTION

[0018] The present application will be further described below in conjunction with the accompanying drawings and embodiments. It should be noted that the embodiments in the present application and the technical features in the embodiments can be combined with each other without conflict. It should be noted that unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as generally understood by those skilled in the art to which the present application belongs. The present application discloses that the "including" or "containing" and similar words mean that the elements or objects before the word cover the elements or objects listed after the word and their equivalents, and do not exclude other elements or objects.

[0019] In one aspect, the present application provides a method for constructing a construction parameter chart of dynamic killing of a blowout well, comprising the following steps: S1: obtaining field data of a target well. Optionally, the field data includes well profile, drilling assembly, pipe wall absolute roughness, wellhead gas production, wellhead temperature, geothermal gradient, kill fluid density, kill fluid displacement, maximum allowable casing pressure.

[0020] S2: establishing a kill calculation model capable of simulating a kill process under different kill parameters.

[0021] In one specific embodiment, the kill calculation model includes an annular gas-liquid two-phase flow model and boundary conditions, the annular gas-liquid two-phase flow model being established based on a gas mass conservation equation, a liquid mass conservation equation, and a gas-liquid two-phase momentum conservation equation in combination with a drift flow model; and the pressure boundary of the boundary conditions being established according to the pressure relationship of the wellbore in the kill process.

[0022] In the above embodiment, for the three kill processes suitable for different working conditions, the core model of the kill calculation model is the annular gas-liquid two-phase flow model. The annular gas-liquid two-phase flow model is first established based on the gas-liquid mass conservation, momentum conservation equation, and in combination with the drift flow model. Secondly, according to the different wellhead and bottom boundary conditions of each kill process, the kill calculation model of each process is established. Through the kill calculation model, the change of the wellbore parameters under different kill parameters in the kill process can be calculated.

[0023] In one specific embodiment, the gas mass conservation equation is: (1) In the formula, A is the annulus cross-sectional area, m 2 ; f g is the gas phase volume fraction, dimensionless; p g is the gas phase density, kg / cm 3 ; t is the time step, s; v g is the gas phase real velocity, m / s; and x is the spatial step, m. The liquid mass conservation equation is: (2) In the formula, f l is the kill fluid volume fraction, dimensionless; p l is the kill fluid density, kg / cm 3 ; and v l is the kill fluid real velocity, m / s. The gas-liquid two-phase momentum conservation equation is: (3) In the formula, P is the pressure, MPa; p m is the mixed phase density, kg / cm 3 ; and g is the gravitational acceleration, m / s2 ; θ is the well inclination, rad; F m is the miscible friction, MPa; The real gas velocity in the drift flow model is calculated by the following equation: (4) wherein: Co is the gas distribution coefficient; v m is the gas-liquid mixing velocity, m / s; v d is the drift velocity, m / s.

[0024] In one specific embodiment, the gas distribution coefficient is calculated by the following equation: (5) wherein: B is the profile parameter, dimensionless; γ is the profile parameter limiting term between 0 and 1, dimensionless; The gas-liquid mixing velocity is calculated by the following equation: (6) The drift velocity is calculated by the following equation: (7) wherein: K(f g ) is the critical Kutateladze number; v c is the characteristic velocity, m / s; m( ) represents the effect of the well inclination on the drift velocity.

[0025] In one specific embodiment, the specific algorithm of the annular gas-liquid two-phase flow model is as follows: The calculation steps of the gas channeling dynamic process of any two nodes j, j+1 in the annulus from time t to t+1 are as follows: wherein the parameters of the nodes j, j+1 at time n are known.

[0026] 1) Assuming the well bottom pressure of the well bottom node t+1 at time t+1 ; 2) According to , the gas channeling rate equation is used to calculate the well bottom gas channeling rate; 3) The pressure of the node j at time t+1 is estimated ; 4) The density, viscosity, deviation coefficient and other parameters are calculated according to the real gas state equation; 5) The gas holdup of the node j at time t+1 is assumed ; 6) The gas-liquid phase velocities , are calculated according to the continuity equation difference result; 7) The gas holdup is calculated according to the gas holdup equation , and if ( error requirement, generally take 0.01), continue to the next step calculation, otherwise, return to step 5) recalculation until the calculation condition is established; 8) the , , , etc. are substituted into the difference of motion equation to calculate , if , the calculation of node j is finished, continue to take the parameters calculated at node j as known conditions of j+1 point, otherwise, return to step 3) recalculation until all calculation conditions are established; 9) when the calculation is to the wellhead, judge whether the calculation result meets the wellhead boundary condition, if yes, proceed to the next time calculation, otherwise, return to step 1) recalculation until the calculation condition is established.

[0027] In a specific embodiment, for process one suitable for good wellbore integrity condition (strong wellbore pressure-bearing capacity, a suitable density displacement combination can be selected according to actual situation to complete well killing), the boundary conditions include pressure relationship one in annulus during well killing and pressure relationship two in drill pipe; For process two suitable for lower wellbore integrity condition (lower wellbore pressure-bearing capacity, well killing parameters are limited. Process two well killing process is to use light weight killing fluid to kill well first, so that the bottom hole pressure balances the formation pressure, continue to circulate light weight killing fluid until the annulus gas is completely discharged, then inject heavy weight killing fluid until the casing pressure is atmospheric pressure, i.e. only liquid column pressure can balance the formation pressure), the boundary conditions include pressure relationship three and pressure relationship four in annulus and drill pipe during injection of light weight killing fluid, pressure relationship five in annulus during injection of heavy weight killing fluid after exhaust, and pressure relationship six in drill pipe before heavy weight killing fluid enters annulus; and the pressure relationship three is the same as the pressure relationship one, and the pressure relationship four is the same as the pressure relationship two; For process three suitable for extremely low wellbore integrity condition (extremely low wellbore pressure-bearing capacity, well killing parameters are greatly limited, process three well killing process is to use light weight killing fluid to form a certain continuous liquid phase in the annulus (considering cost factor, clear water can be used), reduce formation gas production, then inject heavy weight killing fluid to balance the formation pressure and reduce the casing pressure to atmospheric pressure to complete well killing), the boundary conditions include pressure relationship seven and pressure relationship eight in annulus and drill pipe during injection of light weight killing fluid, pressure relationship nine in annulus during injection of heavy weight killing fluid, and pressure relationship ten in drill pipe before heavy weight killing fluid enters annulus; and the pressure relationship seven is the same as the pressure relationship one, the pressure relationship eight is the same as the pressure relationship two, and the pressure relationship ten is the same as the pressure relationship six.

[0028] In a specific embodiment, the pressure relationship one is: (8) P = P b P = P a P = P gf P = P gh P = P mf P = P mh P = P The pressure relationship two is: (9) P = P t P = P lf P = P lh P = P bit P = P The pressure relationship five is: (10) P = P Lf P = P Lh P = P The pressure relationship six is: (11) The pressure relationship nine is: (12) P = P Mf P = P Mh P = P

[0029] S3: Establishing a critical killing parameter optimization objective function with killing fluid density and killing fluid displacement as optimization parameters and successfully completing killing as an optimization goal with the optimization parameters.

[0030] In order to take killing fluid density and killing fluid displacement as optimization parameters and successfully complete killing as an optimization goal with the optimization parameters, the critical killing parameter optimization objective function first establishes a wellhead casing pressure error function and a killing time error function with density and displacement as variables, and then uses the two error functions to establish an optimization objective function.

[0031] To ensure that the well killing parameters can be completed once, the critical well killing parameter condition of process one is that the casing pressure drops to atmospheric pressure when the gas-liquid mixed phase front just reaches the wellhead position. In a specific embodiment, for process one suitable for good wellbore integrity conditions, the critical well killing parameter optimization objective function includes: (13) (14) For process two, if the density of the weighted well killing fluid is too small, the casing pressure has not dropped to atmospheric pressure when the front end of the weighted well killing fluid circulates to the wellhead. Therefore, the critical well killing parameter of process two is the minimum well killing parameter that can reduce the casing pressure to atmospheric pressure. For process two suitable for low wellbore integrity conditions, the critical well killing parameter optimization objective function includes: (15) (16) For process three, if the well killing parameter of the weighted well killing fluid is too small, the bottom hole pressure may be able to balance the formation pressure, but the casing pressure cannot be reduced to atmospheric pressure, and even steady-state gas-liquid two-phase flow may occur. Therefore, the critical well killing parameter of process three is the well killing fluid density and displacement combination that can reduce the casing pressure to atmospheric pressure and maximize the well killing time. For process three suitable for extremely low wellbore integrity conditions, the critical well killing parameter optimization objective function includes: (17) (18) In the formula, P aerror is the error between the casing pressure and atmospheric pressure, MPa; Q k is the well killing fluid displacement, L / s; Mud k is the optimized well killing fluid density, kg / m 3 ; P p is the formation pressure, MPa; Time error is the time node error, dimensionless; Time is the time node required for well killing, dimensionless; Time0 is the total time node of the bottom hole circulating to the wellhead, dimensionless.

[0032] S4: A genetic optimization algorithm model is established, and the individual fitness value of the genetic optimization algorithm model is calculated in combination with the critical well killing parameter optimization objective function.

[0033] In the present application, the genetic optimization algorithm is a prior art, and the basic steps include initializing the population, fitness evaluation, population selection, gene crossover, and gene mutation, the details of which are as follows: (1) Initialize the population A density displacement combination represents an individual, each individual is composed of two gene segments, respectively representing the density and displacement of the well killing fluid, a certain number of individuals are randomly generated in the value range as the initial population, and each individual represents a potential solution of the optimization problem. The individual is represented by formula (22), and the initial population is represented by formula (23): (22) (23) (2) Fitness evaluation Fitness is an index used to measure the pros and cons of individual solutions, indicating the effect or performance that a solution (individual) can achieve in a specific problem. The higher the fitness value, the better the individual solution, the better the optimization goal of the problem. The fitness value of the individual of the present application is calculated in combination with the critical well killing parameter optimization objective function, and the fitness value of the individual is adjusted by increasing the weight coefficient and the importance of different types of errors.

[0034] In a specific embodiment, the fitness value of the individual of the genetic optimization algorithm model is calculated by the following formula: (19) In the formula: Fitness i is the fitness value of individual i, dimensionless; e is the natural base, dimensionless; w1 and w2 are weight coefficients, and the sum of the two is 1; The total fitness of the current i individuals is represented by: (20) In the formula: C_Fitness i is the total fitness of the i individuals, dimensionless; C_Fitness i-1 is the total fitness of the i individuals, dimensionless; i i -1 individual, dimensionless; The population average fitness is represented by: (21) In the formula: Ave_Fitness N is the population average fitness, dimensionless; N is the population individual number, dimensionless.

[0035] (3) Population selection Selecting the population means selecting excellent individuals as parents to participate in the process of gene inheritance according to the fitness of the individuals. The original roulette selection selects one parent individual at a time according to the fitness of the individual, which may lead to better individuals being selected too much and accelerating convergence, or worse individuals being selected too much and reducing evolution efficiency. Therefore, the improved roulette selection method is adopted in the present application, and a plurality of parent individuals are selected at a time for crossover and mutation operation. The specific steps are as follows:​ ① Definition , and a decimal number is randomly generated ; ② Definition ; , , = 0; ③ Definition ; ④ Determine whether is true; ⑤ If step ④ is false, let , and go to step ③; ⑥ If step ④ is true, let be selected as the next generation parent, and then let ; ⑦ Repeat the above steps until next generation parent individuals are selected.

[0036] (4) Gene crossover Crossover refers to combining the genes of parent individuals to produce offspring individuals. The core purpose of crossover is to pass the excellent genes (solution characteristics) of parent individuals to offspring. Single-point crossover is used, as shown in Figure 4 , to convert the density and displacement values into binary data strings, and to achieve crossover by exchanging gene fragments at a certain cutting point. The first 4 binary codes of the density binary string are exchanged, and the first 2 binary codes of the displacement binary string are exchanged. The crossover probability is 60% to 90%.

[0037] (5) Gene mutation Population mutation refers to the differences in genetic characteristics between different individuals of a species. Mutation is achieved by changing the value of a bit or multiple bits in the gene binary string. As shown in Figure 5 , if the bit value is 1, it is changed to 0; if the bit value is 0, it is changed to 1. The probability of gene mutation is usually very small, generally 1% to 5%.

[0038] As shown in Figure 6 , the basic order of the genetic optimization algorithm process is to initialize the population, calculate the fitness, then select the next generation parents for gene crossover and gene mutation to obtain offspring, and then update the population. The loop operation is repeated until the set number of iterations is reached.

[0039] S5: Simulate the kill well process through the kill well calculation model, and combine the critical kill well parameter optimization objective function and the genetic optimization algorithm model to obtain multiple sets of critical kill fluid density and critical kill fluid displacement.

[0040] In the present application, based on the complementary principle of the well killing fluid density and displacement, it can be known that the critical well killing fluid density and displacement exist multiple solutions, therefore, multiple sets of critical well killing fluid density and displacement can be obtained through multiple optimization calculations.

[0041] S6: drawing a density and displacement chart by using the multiple sets of critical well killing fluid density and displacement, and combining the limitation range of density and displacement under the actual conditions to obtain the parameter feasible region of density and displacement, thereby obtaining the well kick killing construction parameter chart of the blowout well.

[0042] In a specific embodiment, the density and displacement combination during the well killing process is too small to establish an effective liquid column in the well, therefore, it is necessary to ensure that the density and displacement combination is greater than the minimum density and displacement combination. The criterion of the well killing displacement and density relationship of the liquid column in the well is as follows: (24) In the formula, μ l is the well killing fluid viscosity, Pa·s; μ g is the gas viscosity, Pa·s; q g is the gas invasion rate, m 3 / s.

[0043] The minimum well killing fluid density and minimum well killing fluid displacement are determined in combination with the actual conditions, and the rated power of the pump is also considered to establish the well killing fluid density and displacement constraints as follows: (25) (26) In the formula, Mud kmin is the minimum well killing fluid density, g / cm 3 ; Mud kmax is the maximum well killing fluid density, g / cm 3 ; Q kmin is the minimum well killing fluid displacement, L / s; Q kmax is the maximum well killing fluid displacement, L / s.

[0044] On the other hand, the present application also provides a well kick killing construction parameter chart of the blowout well, which is constructed by using the construction method of the well kick killing construction parameter chart of the blowout well according to any one of the above.

[0045] In a specific embodiment, taking a certain blowout well as an example, the construction parameter chart of the blowout well is constructed by using the construction method of the well kick killing construction parameter chart of the blowout well according to the present application. In the present embodiment, for the process one, the process two and the process three, the population iteration is 50 times, and the population optimal fitness, the population average fitness, the optimal density and displacement of the well killing fluid are changed as shown in Table 1. Figure 7-9 Figure 7-9 ​It can be seen that the population average fitness tends to converge from the 35th generation, and the fluctuations are caused by gene mutation, which helps to enhance the exploration of the solution space. For process one, the critical kill fluid density converges to 1.79 g / cm 3 , and the displacement converges to 21 L / s. For process two kill, the weighted kill fluid density converges to 1.37 g / cm 3 , and the displacement converges to 29 L / s. For process three kill, the weighted kill fluid density converges to 1.82 g / cm 3 , and the displacement converges to 22 L / s.

[0046] Many restrictions in actual well killing operations may not be able to set the well killing parameters according to the optimization results. In theory, there are multiple solutions for kill fluid density and displacement, that is, the decrease and increase of density can be balanced by the increase and decrease of displacement. Using this multiple solution principle, multiple sets of critical kill fluid density and displacement can be obtained by optimization calculation, and then a kill parameter chart is formed. In this embodiment, it is assumed that the maximum kill displacement that can be achieved under the maximum pump power is 100 L / s. The construction parameter charts obtained by process one, process two and process three kill are shown in Figure 10-12 The density and displacement on the curve of the chart are the critical density and displacement, and combined with the maximum displacement limit, the green area on the right side of the curve is the feasible area of the well killing parameters, and the well killing parameters in this area can successfully complete the well killing.

[0047] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above, it is not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present application are still within the scope of the technical solution of the present application.

Claims

1. A method for constructing a graph of operational parameters for a power kill operation in a blowout well, characterized in that, The method comprises the following steps: S1: obtaining field data of a target well; S2: establishing a kill calculation model capable of simulating a kill process under different kill parameters; S3: taking kill fluid density and kill fluid displacement as optimization parameters, and taking that the optimization parameters can just successfully complete the kill as an optimization target, to establish a critical kill parameter optimization target function; S4: establishing a genetic optimization algorithm model, and calculating individual fitness values of the genetic optimization algorithm model in combination with the critical kill parameter optimization target function; S5: simulating a kill process through the kill calculation model, and obtaining multiple sets of critical kill fluid density and critical kill fluid displacement by combining the critical kill parameter optimization target function and the genetic optimization algorithm model for optimization calculation; S6: drawing a density-displacement chart by using the multiple sets of critical kill fluid density and critical kill fluid displacement, and obtaining a parameter feasible region of density and displacement in combination with a limitation range of density and displacement in real conditions, to obtain a blowout well dynamic kill construction parameter chart.

2. The method for constructing a dynamic kill construction parameter graph for a blowout well according to claim 1, wherein, In step S1, the field data comprises wellbore structure, drilling tool assembly, pipe wall absolute roughness, wellhead gas production, wellhead temperature, geothermal gradient, kill fluid density, kill fluid displacement, and maximum allowable casing pressure.

3. The method for constructing a dynamic kill construction parameter graph for a blowout well according to claim 1, wherein, In step S2, the kill calculation model comprises an annular gas-liquid two-phase flow model and boundary conditions. The annular gas-liquid two-phase flow model is established based on a gas mass conservation equation, a liquid mass conservation equation, and a gas-liquid two-phase momentum conservation equation in combination with a drift flow model. The pressure boundary of the boundary conditions is established according to the pressure relationship of the wellbore in the kill process.

4. The method for constructing a dynamic kill construction parameter graph for a blowout well according to claim 3, wherein, The gas mass conservation equation is: （1） where: A = annulus cross-sectional area, m 2 ; f g = gas phase volume fraction, dimensionless; p g = gas phase density, kg / cm 3 ; t is the time step, s; v g is the gas phase real velocity, m / s; x is the spatial step, m; The liquid mass conservation equation is: （2） where: f l is the volume fraction of the kill fluid, dimensionless; p l is the density of the kill fluid, kg / cm 3 ; v l is the real velocity of the kill fluid, m / s; The gas-liquid two-phase momentum conservation equation is: （3） In the formula: P is the pressure, MPa; ρ m The density is the miscibility, in kg / cm³. 3 g is the acceleration due to gravity, m / s² 2 θ is the well inclination angle, in rad; F m For miscible friction, MPa; The gas phase real velocity in the drift flow model is calculated by the following formula: （4） where: Co is the gas phase distribution coefficient; v m is the gas-liquid mixing velocity, m / s; v d is the drift velocity, m / s.

5. The method for constructing a dynamic kill well construction parameter graph for a blowout well according to claim 4, wherein, The gas distribution coefficient is calculated by the following formula: （5） In the formula, B is a section parameter, dimensionless; γ is a section parameter limiting item between 0 and 1, dimensionless; The gas-liquid mixed velocity is calculated by the following formula: （6） The drift velocity is calculated by the following formula: （7） where: K(f g ) is the critical Kutateladze number; v c is the characteristic velocity, m / s; m characterizes the effect of the inclination angle on the drift velocity.

6. The method for constructing a dynamic kill well construction parameter graph for a blowout well according to claim 3, wherein, For process one suitable for a good wellbore integrity condition, the boundary conditions comprise a pressure relationship one in the annulus and a pressure relationship two in the drill pipe during the kill process. For process two suitable for a lower wellbore integrity condition, the boundary conditions comprise a pressure relationship three in the annulus and a pressure relationship four in the drill pipe during the injection of light kill fluid, a pressure relationship five in the annulus after exhaust, and a pressure relationship six in the drill pipe before the heavy kill fluid enters the annulus; the pressure relationship three is the same as the pressure relationship one, and the pressure relationship four is the same as the pressure relationship two. For process three suitable for an extremely low wellbore integrity condition, the boundary conditions comprise a pressure relationship seven in the annulus and a pressure relationship eight in the drill pipe during the injection of light kill fluid, a pressure relationship nine in the annulus during the injection of heavy kill fluid, and a pressure relationship ten in the drill pipe before the heavy kill fluid enters the annulus; the pressure relationship seven is the same as the pressure relationship one, the pressure relationship eight is the same as the pressure relationship two, and the pressure relationship ten is the same as the pressure relationship six.

7. The method for constructing a dynamic kill construction parameter graph for a blowout well according to claim 6, wherein, The pressure relationship one is: （8） where: P b is the bottom hole pressure, MPa; P a is the casing pressure, MPa; P gf is the gas circulation friction, MPa; P gh is the gas column pressure, MPa; P mf is the gas-liquid mixed phase circulating resistance, MPa; P mh is the gas-liquid mixed phase static pressure, MPa; The pressure relationship two is: （9） where: P t Ppump is the pump pressure, MPa; lf Pcirc is the circulating friction of the kill fluid, MPa; lh Pcolumn is the fluid column pressure, MPa; bit Pbit is the bit pressure drop, MPa; The pressure relationship five is: （10） wherein: P Lf P is the circulating friction of the weighted kill fluid, MPa; P Lh P is the hydrostatic pressure of the weighted kill fluid, MPa; The pressure relationship six is: （11） The pressure relationship nine is: （12） wherein: P Mf Pcirc is the circulating friction of the gas and weighted kill fluid mixture phase, MPa Mh Pstat is the static pressure of the gas and weighted kill fluid mixture phase, MPa.

8. The method for constructing a dynamic kill construction parameter graph for a blowout well according to claim 7, wherein, In step S3, for the process one suitable for the good wellbore integrity condition, the critical kill parameter optimization objective function comprises: （13） （14） For the process two suitable for the lower wellbore integrity condition, the critical kill parameter optimization objective function comprises: （15） （16） For the process three suitable for the extremely low wellbore integrity condition, the critical kill parameter optimization objective function comprises: （17） （18） where: P aerror is the error between casing pressure and atmospheric pressure, MPa; Q k is the displacement of the kill fluid, L / s; Mud k is the optimized kill fluid density, kg / m 3 ; P p is the formation pressure, MPa; Time error is the time node error, dimensionless; Time is the time node required for killing, dimensionless; Time0 is the total time node from the bottom of the well to the wellhead, dimensionless.

9. The method for constructing a dynamic kill construction parameter graph for a blowout well according to claim 8, wherein, In step S4, the individual fitness value of the genetic optimization algorithm model is calculated by the following formula: （19） where: Fitness i is the individual fitness value of individual i, dimensionless; e e is a natural base, and dimensionless; w1 and w2 are weight coefficients, and the sum of the two is 1; The total fitness of the current i individuals is represented as: （20） where: C_Fitness is the fitness of the individual; and i is the total fitness of the individuals, dimensionless. i the total fitness of the individuals, dimensionless. C_Fitness i-1 For i -1 total fitness of the individual, dimensionless; The population average fitness is represented as: （21） wherein: Ave_Fitness N is the population average fitness, dimensionless; N is the population size, dimensionless.

10. A graph for well kill operation parameters in a blowout well, characterized by, The construction method of the well-killing construction parameter chart of the empty well is constructed by using the construction method of the well-killing construction parameter chart of the empty well in any one of claims 1-9.

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