Drilling fluid hoisting and filling volume calculation method based on control of oil and gas channeling speed to be zero

Abstract

The invention relates to the technical field of oil and gas development well control, in particular to a drilling fluid hoisting and filling volume calculation method based on zero oil and gas channeling speed control. Comprising the following steps that after well leakage return is found, drilling fluid is fully circulated, and the oil and gas channeling speed is mastered; calculating density distribution of oil gas and drilling fluid in the shaft; calculating the critical leakage velocity at which oil gas does not move upwards in the drilling stopping static process; determining the hoisting and filling volume of the drilling fluid in the static period, and obtaining the drilling fluid speed in the drilling pulling-out process and the drilling fluid viscosity change in the drilling pulling-out period; calculating the migration velocity of the bubbles after being disturbed in the trip-out process; the critical leakage velocity and the drilling fluid hanging and filling volume are obtained. The method disclosed by the invention has the beneficial effects that through the oil and gas channeling speed obtained through field measurement, an oil and gas channeling speed calculation model in the pulling-out process is established, the critical leakage speed for controlling the oil and gas channeling speed to be not greater than zero is determined, and the drilling fluid hoisting and filling volume in the pulling-out process of the drill column is accurately calculated, so that the operation safety is ensured.

Description

Technical Field

[0001] This invention relates to the field of well control technology for oil and gas development, and in particular to a method for calculating the volume of drilling fluid used for well filling based on controlling the upward flow rate of oil and gas to zero. Background Technology

[0002] As oil and gas development expands into deeper areas and the deep sea, the geological conditions encountered during drilling and completion are becoming increasingly complex. Drilling fluid injection is a crucial method for achieving pressure balance between the wellbore and formation by intermittently and continuously injecting drilling fluid into the wellbore, thereby slowing down oil and gas upwelling and reducing risks such as blowouts and spills. Drilling fluid injection technology has demonstrated significant application value in tripping, completion, and plugging operations. However, the implementation of drilling fluid injection often relies on the experience of field engineers, leading to insufficient or excessive injection. Existing technicians have established a functional relationship between annular fluid level height and leakage rate using fluid level monitoring and proposed a safe time calculation model for drilling fluid injection. However, this method does not consider the impact of oil and gas upwelling rate, which can easily cause oil and gas to migrate to the wellhead, thus increasing well control risks.

[0003] In addition, Chinese patent application number CN202311496107.5, entitled "Calculation Method of Mud Supplementation Volume Based on Annular Fluid Level Monitoring," includes the following steps: establishing a model of the relationship between the leakage rate and fluid level during drilling fluid loss, predicting the location of the leakage equilibrium point, and calculating the leakage pressure difference at each measuring point; establishing a model of the relationship between the leakage pressure difference and the leakage rate, and establishing a leakage dynamic function; calculating the fluid level height required to compensate for the drill string shortage; calculating the fluid level height required to balance the formation high pressure and determining the safe fluid level height; and calculating the time from the current fluid level to the safe fluid level to obtain the mud suspension volume. This invention also utilizes fluid level monitoring technology, observing the fluid level drop rate to fit a model of the relationship between the leakage rate and fluid level during drilling fluid loss, determining whether drilling fluid suspension is needed and the suspension volume. However, it still has the following shortcomings: the aforementioned invention application does not consider the oil and gas surge rate during the suspension and tripping process. If this factor is not considered during tripping, it can easily lead to oil and gas surging to the wellhead, causing risks such as blowouts. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned deficiencies in existing technologies by providing a method for calculating drilling fluid loading volume based on controlling the oil and gas upward velocity to zero. This method utilizes field measurements of the oil and gas upward velocity, combined with wellbore structure and drill string assembly, to calculate the influence of tripping speed on the oil and gas upward velocity. A calculation model for the oil and gas upward velocity during tripping is established, determining the critical leakage rate to ensure the oil and gas upward velocity is not greater than zero. This allows for precise calculation of the drilling fluid loading volume during drill string tripping, thereby ensuring operational safety.

[0005] The present invention discloses a method for calculating drilling fluid injection volume based on controlling the upward velocity of oil and gas to zero. The technical solution includes the following steps: 1. After discovering well leakage and return, fully circulate the drilling fluid and monitor the rate of oil and gas surge. II. Calculate the density distribution of oil, gas, and drilling fluid in the wellbore based on the temperature and pressure distribution in the wellbore; (1) The distribution of wellbore temperature after drilling stops is equivalent to the formation temperature. By selecting a point every 100 meters, the distribution of wellbore pressure and drilling fluid density is calculated using the superposition method. (2) Calculate the density of natural gas downhole based on the temperature and pressure field; III. Calculate the critical leakage rate at which oil and gas no longer rise during the shutdown and stagnant process, taking into account the wellbore size and drill string assembly; IV. Determining the drilling fluid loading volume during the static period based on the critical leakage rate: , in: V The volume of drilling fluid being poured in is in meters. 3 ; t For time, s; 5. After a period of time, monitor the liquid level and determine whether the irrigation volume is reasonable based on the changes in the liquid level. (1) When the liquid level is equal to the previous liquid level, it means that the drilling fluid filling volume meets the filling requirements during the static period; (2) When the fluid level is higher than the previous fluid level, reduce the amount of drilling fluid poured in; when the fluid level is lower than the previous fluid level, increase the amount of drilling fluid poured in. (3) Once the liquid level has stabilized, prepare to pull up the drill string; VI. Determine the size of the air bubbles in the wellbore based on the upward velocity of oil and gas; 7. Based on the wellbore size and drill string assembly, the drilling fluid velocity and viscosity changes during the tripping process are obtained; 8. Calculate the migration speed of the air bubble after it is disturbed during the drilling process; The rising velocity of bubbles during tripping in drilling fluid is obtained based on the calculation method for bubble migration velocity in drilling fluid. The actual migration velocity of bubbles during tripping can be calculated using the following formula: , in: The actual upward velocity of the bubble is expressed in m / s; v g The upward velocity of the bubble under the influence of drilling fluctuations, in m / s; C 0 is the distribution coefficient; 9. Based on the fundamental principle that the drilling fluid descent rate is greater than the oil and gas upflow rate, the critical leakage rate and drilling fluid loading volume are obtained. 10. Calculate the required leakage pressure differential based on the functional relationship between leakage pressure differential and leakage velocity: , Where: Δ p Leakage pressure differential, MPa; a , b The coefficient for calculating leakage pressure difference; 11. For every three drill strings or one drill collar drilled, liquid level monitoring technology should be used to monitor the liquid level height at this time and compare it with the liquid level. The subsequent operation procedure should be determined based on the change in liquid level height. (1) When the fluid level is equal to the previous fluid level, it means that the drilling fluid grouting volume meets the grouting requirements during the tripping period. At this time, continue grouting according to this volume. (2) When the liquid level is higher than the previous liquid level, it is necessary to determine whether the higher liquid level is caused by excessive drilling fluid injection or by insufficient grouting volume leading to increased overflow. The judgment method is to observe statically. If the liquid level drops, it indicates that the drilling fluid injection volume is excessive. (3) When the fluid level is lower than the previous fluid level, it indicates that the drilling fluid injection volume is insufficient and it is necessary to increase the drilling fluid injection volume. 12. After reaching the target well section, proceed with other operations.

[0006] Preferably, the specific method in step three above includes the following: (1) The relationship between the drilling fluid descent rate and the leakage rate during the static period is shown in the following formula: , in: v ms The drilling fluid descent velocity during the stationary period, in m / s; v loss Let m be the leakage rate. 3 / h; D w The diameter of the wellbore is in meters (m). D d Drill pipe diameter, in meters (m); (2) The critical leakage rate was calculated based on the principle of balancing the drilling fluid descent rate and the oil and gas upflow rate; , in: v gm The velocity of the oil and gas rises is expressed in m / s.

[0007] Preferably, the specific steps in step six above include the following: (1) The calculation method for the transport velocity of a single bubble in a static fluid is as follows: , in:d The diameter of the oil droplet / bubble is in meters (m). v is the upward velocity of a single bubble in a static liquid column, in m / s; ρ g The density of the gas is in g / cm³. 3 ; ρ m Density of drilling fluid at the bottom of the well, in g / cm³ 3 ; C d The drag coefficient is dimensionless. (2) Due to the mutual influence between bubbles, the corrected bubble migration velocity in the drilling fluid is shown in the following formula: , Where: α is the gas content; This is a correction factor; (3) Where C d The drag coefficient can be calculated using the following formula: , Where: Re is the Reynolds number; (4) The Reynolds number for the transport of bubbles in a static liquid column is calculated using the following formula: , in: K The viscosity coefficient is Pa·s^n; (5) The bubble size is calculated by combining the oil and gas upwelling velocity measured on site with the above formula.

[0008] Preferably, the specific steps in step seven above include the following: (1) During the tripping process, drilling fluid will replenish the original drill string position, and the faster the tripping speed, the faster the drilling fluid replenishment speed; the relationship between the drilling fluid annular velocity and the tripping speed is shown in the following formula: , in: v m The annular velocity is m / s; v q The drilling speed is measured in m / s. (2) Due to the shear dilution effect of drilling fluid, the viscosity of drilling fluid is calculated using the following formula as it flows: , , Where: γ is the shear rate, s -1 ; μ p ρ represents the drilling fluid viscosity, Pa·s.

[0009] Preferably, the specific steps in step nine above include the following: (1) The calculation method for the drilling fluid descent rate during tripping is as follows: , in: v mu The drilling fluid descent rate during tripping out of the well is expressed in m / s. (2) Based on the fundamental principle that the drilling fluid descent rate is greater than the oil and gas upflow rate, a method for calculating the critical leakage rate required for the drilling fluid is derived. When the leakage rate is greater than 10m... 3 When the drilling speed is reduced to 0.1 m / s, the leakage rate is recalculated. Even when the speed is reduced to 0.1 m / s, the leakage rate is still greater than 10 m / s. 3 / h, start drilling at a speed of 0.1m / s: ; (3) The ratio K between the drilling fluid injection volume and the drill string tripping volume B The calculation method is as follows: , in: L The height of the drill string to be pulled out, in meters (m); V 钻柱 This represents the drill string volume; K B This represents the ratio between the volume of drilling fluid injected and the volume of the drill string pulled out.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention addresses the well control risks caused by excessive or insufficient drilling fluid volume during tripping after well loss of circulation. By measuring the oil and gas upwelling velocity before tripping and combining it with parameters such as well structure, drill string assembly, and drilling fluid properties, the invention calculates the variation law of oil and gas upwelling velocity during tripping. By controlling the loss of circulation velocity, the invention enables the suspension or reversal of air bubbles downhole, achieving accurate calculation of drilling fluid volume and thus ensuring operational safety. In addition, the critical leakage rate proposed in this invention is calculated for controllable downhole micro-leakage. The safe leakage rate of drilling fluid under different tripping speed conditions is calculated. Under this leakage rate condition, the air bubbles are suspended or turned in the wellbore, thereby calculating the volume of drilling fluid poured during tripping. The downhole is kept in a micro-leakage state during the tripping operation, and the drilling is safely and quickly tripped to the target area. Attached Figure Description

[0011] Figure 1 This is a layout diagram of the hoisting and drilling system of the present invention; Figure 2 The required drilling fluid volume and corresponding leakage rate under different tripping speeds for a certain well; Figure 3The required drilling fluid injection volume and corresponding leakage rate for a certain well under different oil and gas upwelling rates; In the diagram: 1. Drilling fluid tank; 2. Drilling pump; 3. Wellhead blowout preventer; 4. Fluid level monitoring system. Detailed Implementation

[0012] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0013] Example 1, referring to Figure 1 The present invention mentions a drilling fluid tank 1, a drilling pump 2, a wellhead blowout preventer 3, and a fluid level monitoring system 4. The wellhead blowout preventer 3 is installed at the top of the wellbore. The drilling pump 2 and the drilling fluid tank 1 are connected to the wellhead blowout preventer 3 by pipelines. One side of the wellhead blowout preventer 3 is connected to the fluid level monitoring system 4 by a data cable.

[0014] The present invention provides a method for calculating the volume of drilling fluid injection based on controlling the upward velocity of oil and gas to zero, comprising the following steps: 1. After discovering well leakage and return, fully circulate the drilling fluid and monitor the rate of oil and gas surge. II. Calculate the density distribution of oil, gas, and drilling fluid in the wellbore based on the temperature and pressure distribution in the wellbore; (1) The wellbore temperature distribution after drilling is stopped can be equivalent to the formation temperature. The wellbore pressure can be calculated by selecting a point every 100 meters and using the superposition method to obtain the wellbore pressure and drilling fluid density distribution: , , in: ρ 0 Density of drilling fluid at the surface, in g / cm³ 3 ; ρ mi The drilling fluid density at a well depth of 100 m is given in g / cm³. 3 ; g The acceleration due to gravity is m / s². 2 ; a 1. a 2 represents the temperature coefficient; a 3 represents the pressure coefficient; a 4 represents the temperature-pressure interaction coefficient; P i The wellbore pressure at a depth of 100i meters, in MPa; T i The wellbore temperature at a depth of 100 m, in K; h n Let the depth be m; (2) Calculate the density of natural gas downhole based on the temperature and pressure field; , in: ρ g The density of the gas is in g / cm³. 3 ; The specific gravity of natural gas; Z It is the compression factor; T Temperature, K; P Pressure, MPa; III. Calculate the critical leakage rate at which oil and gas no longer rise during the shutdown and quiescent process by combining wellbore size, drill string assembly and other relevant parameters; (1) The relationship between the drilling fluid descent rate and the leakage rate during the static period is shown below; , in: v ms The drilling fluid descent velocity during the stationary period, in m / s; v loss Let m be the leakage rate. 3 / h; D w The diameter of the wellbore is in meters (m). D d Drill pipe diameter, in meters (m); (2) The critical leakage rate can be calculated based on the principle of balancing the drilling fluid descent rate and the oil and gas upflow rate; , in: v gm The velocity of oil and gas rising upwards is expressed in m / s. IV. Determining the drilling fluid loading volume during the static period based on the critical leakage rate: , in: V The volume of drilling fluid being poured in is in meters. 3 ; t For time, s; 5. After a period of time, monitor the liquid level and determine whether the irrigation volume is reasonable based on the changes in the liquid level. (1) When the liquid level is equal to the previous liquid level, it means that the drilling fluid grouting volume meets the grouting requirements during the static period; (2) When the fluid level is higher than the previous fluid level, reduce the amount of drilling fluid poured in; when the fluid level is lower than the previous fluid level, increase the amount of drilling fluid poured in. (3) Once the liquid level has stabilized, prepare to pull up the drill string; VI. Determine the size of the air bubbles in the wellbore based on the upward velocity of oil and gas; (1) The calculation method for the transport velocity of a single bubble in a static fluid is as follows: , in: d The diameter of the oil droplet / bubble is in meters (m). v is the upward velocity of a single bubble in a static liquid column, in m / s; ρ g The density of the gas is in g / cm³. 3 ; ρ m Density of drilling fluid at the bottom of the well, in g / cm³ 3 ; C d The drag coefficient is dimensionless. (2) Due to the mutual influence between bubbles, the corrected bubble migration velocity in the drilling fluid is shown in the following formula: , Where: α is the gas content; This is a correction factor, typically taken as 1.5-2; (3) Where C d The drag coefficient can be calculated using the following formula: , Where: Re is the Reynolds number; (4) The Reynolds number for the transport of bubbles in a static liquid column is calculated using the following formula: , in: K The viscosity coefficient is Pa·s^n; (5) The bubble size can be calculated by combining the oil and gas upwelling velocity measured on site with the above formula; 7. Based on the wellbore size and drill string assembly, calculate the drilling fluid velocity and the change in drilling fluid viscosity during the tripping process; (1) During the tripping process, the drilling fluid will be rapidly replenished to the original position of the drill string, and the faster the tripping speed, the faster the drilling fluid replenishment speed; the relationship between the annular velocity of the drilling fluid and the tripping speed is shown in the following formula: , in: v m The annular velocity is m / s; v q The drilling speed is measured in m / s. (2) Due to the shear dilution effect of drilling fluid, the viscosity of drilling fluid is calculated using the following formula as it flows: , , Where: γ is the shear rate, s -1 ; μ p The value is the drilling fluid viscosity, Pa·s; 8. Calculate the migration speed of the air bubble after it is disturbed during the drilling process; (1) The rising velocity of the bubbles during the tripping disturbance process is obtained according to the calculation method of the bubble migration velocity in the drilling fluid. The actual migration velocity of the bubbles during tripping can be calculated according to the following formula: , in: The actual upward velocity of the bubble is expressed in m / s; v g The upward velocity of the bubble under the influence of drilling fluctuations, in m / s; C 0 is the distribution coefficient; 9. Based on the fundamental principle that the drilling fluid descent rate is greater than the oil and gas upflow rate, the critical leakage rate and drilling fluid loading volume are calculated. (1) The calculation method for the drilling fluid descent rate during tripping is as follows: , in: v mu The drilling fluid descent rate during tripping out of the well is expressed in m / s. (2) Based on the fundamental principle that the drilling fluid descent rate is greater than the oil and gas upflow rate, a method for calculating the critical leakage rate required for the drilling fluid is derived. When the leakage rate is greater than 10m... 3 When the drilling speed is reduced to 0.1 m / s, the leakage rate is recalculated. Even when the speed is reduced to 0.1 m / s, the leakage rate is still greater than 10 m / s. 3 / h, start drilling at a speed of 0.1m / s: ; (3) The ratio K between the drilling fluid injection volume and the drill string tripping volume B The calculation method is as follows: , in: L The height of the drill string to be pulled out, in meters (m); V 钻柱 This represents the drill string volume; K B This represents the ratio between the volume of drilling fluid injected and the volume of drill string pulled out. 10. Calculate the required leakage pressure differential based on the functional relationship between leakage pressure differential and leakage velocity: , Where: Δ p Leakage pressure differential, MPa; a , bThe coefficient for calculating leakage pressure difference; 11. For every three drill strings or one drill collar drilled, liquid level monitoring technology should be used to monitor the liquid level height and compare it with the liquid level. The subsequent operation procedure should be determined based on the change in liquid level height. (1) When the fluid level is equal to the previous fluid level, it means that the drilling fluid grouting volume meets the grouting requirements during the tripping period. At this time, continue grouting according to this volume. (2) When the liquid level is higher than the previous liquid level, it is necessary to determine whether the higher liquid level is caused by excessive drilling fluid injection or by insufficient grouting volume leading to increased overflow. The judgment method is to observe statically. If the liquid level drops, it indicates that the drilling fluid injection volume is excessive. (3) When the fluid level is lower than the previous fluid level, it indicates that the drilling fluid injection volume is insufficient and it is necessary to increase the drilling fluid injection volume. 12. After reaching the target well section, proceed with other operations.

[0015] Example 2, refer to Figure 2 and Figure 3 A well was selected with an open hole diameter of 215 mm, a casing diameter of 244.5 mm, and a drill string diameter of 127 mm. The measured oil and gas upwelling velocity was 30 m / h. Based on these simulation conditions, the variation of drilling fluid injection volume and critical leakage velocity under different tripping speeds was established, as shown in the figure. When the tripping speed is 0.1 m / s, three times the volume of drilling fluid needs to be injected into the wellbore for each drill string pulled out, while the critical leakage velocity needs to be controlled at 9.13 m / s. 3 At a certain speed ( / h), it can be ensured that oil and gas will not migrate upwards during the tripping process. Furthermore, the higher the tripping speed, the smaller the volume of drilling fluid required for injection, but the corresponding critical leakage rate must be higher. In addition, as the upward velocity of oil and gas increases, the required volume of drilling fluid increases, and the critical leakage rate also increases accordingly.

[0016] The above description is merely a partial preferred embodiment of the present invention. Any person skilled in the art can modify the above-described technical solutions or modify them into equivalent technical solutions. Therefore, any simple modifications or equivalent transformations made based on the technical solutions of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for calculating the volume of a drilling fluid to be pumped based on the control of the rate of gas migration to zero, characterized in that: The method comprises the following steps: I. After finding the loss of well leakage, circulating the drilling fluid sufficiently, and grasping the oil and gas channeling speed; II. According to the wellbore temperature and pressure distribution, the density distribution of oil and gas and drilling fluid in the wellbore is calculated; (1) The distribution of wellbore temperature after stopping drilling is equivalent to the formation temperature. By selecting a point every 100 meters, the wellbore pressure and drilling fluid density distribution are calculated by using superposition method; (2) According to the temperature and pressure field, the density of natural gas in the well is calculated; III. The critical leakage rate at which oil and gas no longer channel in the static process of stopping drilling is calculated in combination with the borehole size and drilling assembly; IV. The hoisting and circulating volume of drilling fluid during the static period is determined based on the critical leakage rate: ， wherein: V is the volume of the drilling fluid, m3 3 ; t is the time, s; V. After a period of time, the liquid level is monitored, and whether the hoisting and circulating volume is reasonable is determined according to the change of the liquid level; (1) When the liquid level is equal to the previous liquid level, it indicates that the hoisting and circulating volume of drilling fluid meets the hoisting and circulating demand during the static period; (2) When the liquid level is higher than the previous liquid level, the hoisting and circulating volume of drilling fluid is reduced; when the liquid level is lower than the previous liquid level, the hoisting and circulating volume of drilling fluid is increased; (3) When the liquid level is stable, the drilling is prepared to be started; VI. The size of the gas bubble in the wellbore is back calculated according to the oil and gas channeling speed; VII. The drilling fluid speed and the viscosity change of drilling fluid during the tripping process are obtained in combination with the borehole size and drilling assembly; VIII. The migration speed of the gas bubble after being disturbed in the tripping process is calculated; The ascending speed of the gas bubble in the tripping disturbance process is obtained according to the migration speed calculation method of the gas bubble in the drilling fluid, and the actual migration speed of the gas bubble during the tripping process can be calculated according to the following formula: ， wherein: Vb is the actual bubble rise velocity, m / s; v g Vb is the bubble rise velocity under the effect of the drilling wave, m / s; C 0 is the distribution coefficient; IX. The critical leakage rate and the hoisting and circulating volume of drilling fluid are obtained based on the principle that the descending speed of drilling fluid is greater than the channeling speed of oil and gas; X. The leakage pressure difference to be maintained is calculated according to the functional relationship between the leakage pressure difference and the leakage speed: ， wherein: Δ p is the differential pressure of the loss, MPa; a , b is the differential pressure of the loss calculation coefficient; XI. The liquid level at this time is monitored by using the liquid level monitoring technology every time three column drill strings or one column drill collar are tripped out, and the liquid level is compared with the liquid level, and the subsequent operation process is determined according to the change of the liquid level; (1) When the liquid level is equal to the previous liquid level, it indicates that the hoisting and circulating volume of drilling fluid meets the hoisting and circulating demand during the tripping period, and the volume is continued to be grouted at this time; (2) When the liquid level is higher than the previous liquid level, it is needed to determine whether the part of the liquid level that is higher than the previous liquid level is caused by the excessive grouting volume of drilling fluid or by the intensified overflow caused by the insufficient grouting volume; the determination method is static observation, and if the liquid level decreases, it indicates that the hoisting and circulating volume of drilling fluid is excessive; (3) When the liquid level is lower than the previous liquid level, it indicates that the hoisting and circulating volume of drilling fluid is insufficient, and the hoisting and circulating volume of drilling fluid needs to be increased; XII. After the tripping reaches the target well section, other operations are performed.

2. The hoisting and circulating volume calculation method of drilling fluid based on controlling the oil and gas channeling speed to be zero according to claim 1, characterized in that: The specific method in step III comprises the following: (1) The relationship between the descending speed of drilling fluid and the leakage speed during the static period is as follows: ， wherein: v ms is the rate of drilling fluid descent during static periods, m / s; v loss is the rate of loss, m 3 / h; D w is the borehole diameter, m; D d is the drill pipe diameter, m; (2) The critical leakage rate is calculated based on the principle that the descending speed of drilling fluid is balanced with the channeling speed of oil and gas; ， wherein: v gm is the oil and gas upward migration velocity, m / s.

3. The hoisting and circulating volume calculation method of drilling fluid based on controlling the oil and gas channeling speed to be zero according to claim 2, characterized in that: The specific steps in step VI comprise the following: (1) The migration speed calculation method of a single gas bubble in the static fluid is as follows: ， wherein: d is the oil drop / bubble diameter, m; v is the single bubble rise velocity in the static column, m / s; ​ g is the gas density, g / cm 3 ; ​ m is the bottom hole drilling fluid density, g / cm 3 ; C d is the drag coefficient, dimensionless; (2) The moving velocity of the modified bubble in the drilling fluid is shown in the following formula due to the mutual influence between the bubbles: ， wherein: a is the gas fraction; is a correction factor; (3) where C d is the drag coefficient, which can be calculated by the formula: ， Where Re is the Reynolds number; (4) The calculation method of the Reynolds number of the bubble moving in the static liquid column is shown in the following formula: ， wherein: K is the consistency factor, Pa s n; The bubble size is calculated by the measured oil and gas channeling speed and the above formula.

4. The drilling fluid displacement volume calculation method based on controlling the oil and gas channeling speed to be zero according to claim 3, characterized in that: The specific steps in step seven include the following: (1) The drilling fluid is supplemented to the original drilling tool position during the drilling tool tripping out process, and the faster the tripping out speed, the faster the drilling fluid supplement speed; the relationship between the drilling fluid annular fluid velocity and the tripping out speed is shown in the following formula: ， wherein: v m is the annular fluid velocity, m / s; v q is the trip velocity, m / s; (2) Due to the shear thinning effect of the drilling fluid, the viscosity of the drilling fluid is calculated by the following formula as the drilling fluid flows: ， ， where: γ is the shear rate, s -1 ; μ p is the viscosity of the drilling fluid, Pa-s.

5. The drilling fluid displacement volume calculation method based on controlling the oil and gas channeling speed to be zero according to claim 4, characterized in that: The specific steps in step nine include the following: (1) The calculation method of the drilling fluid descending speed during the tripping out is shown in the following formula: ， wherein: v mu Vd is the rate of drilling fluid descent during tripping, m / s; (2) Based on the basic principle that the drilling fluid descent speed is greater than the oil and gas channeling speed, the critical loss speed calculation method for drilling fluid is obtained. When the loss speed is greater than 10 m / s, the tripping speed is reduced to recalculate, and when the speed is reduced to 0.1 m / s, the loss speed is still greater than 10 m / s, and the tripping speed is 0.1 m / s: 3 / h. 3 / h. ； (3) The multiple relationship K between the volume of the drilling fluid filled and the drilling string pulled out B The calculation method is: ， where: L m is the height of the tripping out drill string; V 钻柱 V is the volume of the drill string; K B K is the multiple relationship between the volume of the drilling fluid pumped in and the tripping out drill string.

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