Drilling fluid density measuring device and method considering the influence of barite settling rate

Abstract

The present application relates to the technical field of oil drilling, and particularly relates to a drilling fluid density measuring device and method considering the influence of barite settling rate. The technical scheme is as follows: the lower end of a mud tank is connected with a screw pump through a second electronic valve, the upper side of the mud tank is connected with a viscosity agent tank through a pipeline, and the middle part is connected with a viscometer through a pipeline; a wellbore mounting frame is installed on one side of the mud tank, a wellbore is installed on the wellbore mounting frame, the middle part of the wellbore is adjusted in inclination angle through a wellbore angle rotating motor, an inner cylinder for simulating a drill string is installed in the inner cavity of the wellbore, an inner cylinder rotating motor is installed on the top of the inner cylinder, the mud tank is connected with the inner cylinder through a pipeline at the bottom of the inner cylinder, and a plurality of density meters are installed at equal intervals from top to bottom in the inner cylinder. The beneficial effects are as follows: the present application can measure the barite settling rate at different depths and the drilling fluid density under the conditions of different densities, viscosities and barite particle sizes, and can establish a model on the basis of experimental data to predict the drilling fluid density.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil drilling technology, in particular to a drilling fluid density measuring device and method considering the influence of barite settling rate. BACKGROUND

[0002] In drilling operations, the pressure control of the formation is crucial, generally, high-density minerals such as barite and hematite are used to increase the density of the drilling fluid, so as to control the pressure; however, rheological property and settling stability control is one of the main technical difficulties in high-density drilling fluid technology, due to the influence of gravity and other factors, the settling of barite or other weighting materials in the drilling fluid causes the significant heavy particle material to easily settle down from the suspension, this problem in high-angle drilling and completion, during the drilling process, the settling of the weighting material leads to the change of the drilling fluid density used for control, that is designated as "settling" in the drilling industry, the settling can cause the weighting material to hinder the normal operation of the casing or the insufficient drilling fluid density during the cementing operation, causing the well control difficulty and other problems. For example, the shut-in time before completion is often long, that is, the drilling fluid is in a static state for a long time, which can cause the deposition of the weighting material on the top of the drill bit, resulting in the downtime for removing the settled material before starting the operation, increasing the operation time and cost.

[0003] There are many factors affecting the settling, the pore diameter, the pore angle, the borehole length, the annular velocity, the drill pipe rotation, the flow state, the drilling fluid viscosity, the drilling fluid gel strength, the fluid density, the weighting agent density, the particle size and shape, the particle concentration and time, etc. all can affect the settling of the weighting material.

[0004] Through the analysis of the influence of each factor on the settling of barite, the influence law of each factor on the settling rate of barite can be obtained, which is helpful to prevent and solve the barite settling problem on site, and has a positive significance for the design of deepwater oil and gas layer drilling engineering and the improvement of on-site well control decision-making measures.

[0005] At present, people carry out relatively more experimental research on the settling rate of barite in the drilling fluid, but due to the limitation of related experimental equipment and methods, there is a certain error in the final obtained settling rate data. SUMMARY

[0006] The purpose of the present application is to overcome the above-mentioned defects in the prior art, provide a drilling fluid density measuring device and method considering the influence of barite settling rate, which can measure the barite settling rate and drilling fluid density at different depths under the conditions of different density, viscosity and barite particle size, and establish a model based on experimental data to predict the drilling fluid density.

[0007] The application discloses a drilling fluid density measuring device considering the influence of barite settling rate, which is characterized by comprising a mud tank (2), a stirrer (3), a thickening agent tank (4), a viscosity meter (5), an inner cylinder rotating motor (6), a first densimeter (7), a second densimeter (8), a fourth densimeter (10), a first electronic valve (12), a third densimeter (13), a well shaft angle rotating motor (15), a well shaft (16), a data acquisition processing and control center (18), a screw pump (19), a second electronic valve (20) and a well shaft mounting rack (21), the lower end of the mud tank (2) is connected with the screw pump (19) through the second electronic valve (20), the inner cavity of the mud tank (2) is provided with the stirrer (3), the upper side of the mud tank (2) is connected with the thickening agent tank (4) through a pipeline, and the middle part of the mud tank (2) is connected with the viscosity meter (5) through a pipeline; the well shaft mounting rack (21) is arranged on one side of the mud tank (2), the well shaft (16) is arranged on the well shaft mounting rack (21), the middle part of the well shaft (16) is provided with the well shaft angle rotating motor (15) for adjusting the inclination angle, the inner cylinder (16.1) for simulating a drill string is arranged in the inner cavity of the well shaft (16), the top of the inner cylinder (16.1) is provided with the inner cylinder rotating motor (6), the first electronic valve (12) is arranged on one side of the bottom of the inner cylinder (16.1), the outlet of the first electronic valve (12) is connected with the mud tank (2) through a pipeline, the top of the inner cylinder (16.1) is connected with the output end of the screw pump (19) through a pipeline, and the first densimeter (7), the second densimeter (8), the third densimeter (13) and the fourth densimeter (10) are arranged in the inner cylinder (16.1) at equal intervals from top to bottom; the thickening agent tank (4), the viscosity meter (5), the inner cylinder rotating motor (6), the well shaft angle rotating motor (15) and the screw pump (19) are connected with the data acquisition processing and control center (18) through control lines respectively.

[0008] Preferably, the inner cavity of the inner cylinder (16.1) is provided with the stirring paddle (11), one side of the stirring paddle (11) is arranged as an outlet, and the first electronic valve (12) is arranged at the outlet.

[0009] Preferably, the vertical scale (17) is arranged on the outer wall of the well shaft (16) in the axial direction, and the horizontal scale (14) is arranged on the horizontal scale sliding rail (9) in the radial direction.

[0010] Preferably, the horizontal scale sliding rail (9) is arranged on the outer wall of the well shaft (16) in the axial direction, the outer end of the horizontal scale (14) is sleeved on the horizontal scale sliding rail (9) and moves up and down along the horizontal scale sliding rail (9).

[0011] Preferably, the middle part of the wellbore mounting frame (21) is mounted with a wellbore angle rotating motor (15), and the output end of the wellbore angle rotating motor (15) is connected to the middle part of the wellbore (16), the wellbore (16) is driven to have a certain inclination angle by the rotation of the wellbore angle rotating motor (15), and is used for simulating different inclination angles of the inclined shaft.

[0012] Preferably, an electromagnetic flowmeter (1) is mounted on the pipeline between the output end of the screw pump (19) and the inner cylinder (16.1).

[0013] Preferably, four measuring points are arranged equidistantly on the inner cylinder (16.1) of the wellbore (16) to measure the density change of the barite sample liquid to obtain the barite settling rate data, and a mathematical model of the density of the barite sample liquid at a certain depth with respect to different densities, viscosities and barite particle sizes is established, and the specific method is as follows:

[0014] (1.1)

[0015] In the formula, ρ represents the density of the barite sample liquid, g / cm 3 ; ρ0 represents the initial density of the sample liquid, g / cm 3 ; μ represents the viscosity, mPa·s; t represents the time, min; d represents the diameter of the barite, 10 -5 m; h represents the depth from the pipe opening, m; a and b represent the correlation coefficients obtained by fitting, dimensionless.

[0016] The test method of the drilling fluid density measuring device considering the influence of the barite settling rate mentioned in the application comprises the following steps:

[0017] S1, cleaning the experimental device: the entire pipeline and the mud tank (2) are cleaned 2-3 times by circulating system using clean water;

[0018] S2, preparing the experimental sample liquid: first, calculate the approximate water and barite weight required for the experiment, then inject water into the mud tank (2), set the highest speed, open the stirrer (3) and the screw pump (19); then add the barite and viscosity enhancer to the mud tank (2) at a uniform speed, after stirring and circulating for a sufficient time at the highest speed, read the sample liquid density and viscosity in the data acquisition and processing and control center (18), and control the next step of preparation by reading the sample liquid density and viscosity, such as adding water or adding barite and viscosity enhancer, until the set density and viscosity are reached.

[0019] S3, sedimentation experiment: through the data acquisition and processing and control center (18) control experiment required wellbore inclination angle, the rotation speed of the inner tube, the mud circulation flow, in the static sedimentation experiment, the data acquisition and processing and control center (18) control the first electronic valve (12) or the second electronic valve (20) and the stop of the circulation system; see the curve of the reading of each densimeter with time, while the real-time reading of each densimeter is transmitted to the model establishment system through the information acquisition card;

[0020] S4, calculate the barite content reduction rate: through the density value p i,t of each measuring point at different times, the barite content η i，t of the corresponding measuring point i can be calculated, and the calculation formula is as follows:

[0021] (1.2)

[0022] In the formula: p i,t is the density value of each measuring point at different times, g / cm 3 ; η i，t is the barite content of measuring point i; p 重晶石 is the initial density of the barite sample liquid, g / cm 3 ;

[0023] S5, after the experiment, the experimental sample liquid in the mud tank (2) is discharged and injected with clean water, and the experimental sample liquid in the pipeline and the wellbore (16) is displaced with clean water, and the cleaning is repeated for 3-5 times, and the power is turned off.

[0024] Specifically, in the above step S4,

[0025] the theoretical time required for sufficient sedimentation is calculated by the relationship between the settling velocity of barite particles in static or flowing liquid and the length of the pipe column, formula (1.2), and the experimental results are verified by comparing the theoretical time length with the actual sedimentation time.

[0026] (1.3)

[0027] In the formula: u t is the settling velocity, m / s; L is the length of the pipe column, m; T is the predicted settling time, min;

[0028] Through the force analysis of the solid particles in the liquid, it can be known that the solid particles are affected by their own gravity and the buoyancy of the liquid, and the settling velocity calculation formula of the particles in the static liquid is obtained through analysis, as shown in formula (1.3);

[0029] (1.4)

[0030] In the formula: ut settling velocity, m / s; C d drag coefficient, dimensionless; V 3 density of liquid, N / cm S density of solid particle, N / m 3 ;

[0031] When the Reynolds number Re is less than 1, the relative movement between the particle and the liquid belongs to laminar flow. The drag coefficient C d and the free settling velocity formula of the solid particle in the laminar flow region are respectively:

[0032] (1.5)

[0033] (1.6)

[0034] wherein u t settling velocity, m / s; C d drag coefficient, dimensionless; p 3 density of liquid, kg / m s density of solid particle, kg / m 3 kinematic viscosity, mPa·s; d

[0035] When the Reynolds number is 1<Re<1000, it is called transition region settling, which indicates the gradually developed turbulence in the movement of the solid particle. The drag coefficient is

[0036] (1.7)

[0037] wherein u t settling velocity, m / s; C d drag coefficient, dimensionless; p 3 density of liquid, kg / m

[0038] Substitute formula (1.6) into formula (1.4), and the free settling velocity u t of the spherical particle in the transition region can be obtained by calculation.

[0039] When the Reynolds number is 1000<Re<2x10', it is called turbulent region settling, which describes the fully developed turbulence except the boundary layer. The drag coefficient of the spherical solid particle in the turbulent settling is close to a constant C d ≈0.45.

[0040] Substitute C d ≈0.45 into formula (1.4), and the free settling velocity of the solid particle is calculated as shown in formula (1.7):

[0041] (1.8)

[0042] In the formula: u t Settling velocity, m / s; d solid particle diameter, m; V liquid specific gravity, N / cm 3 ; V S Specific gravity of solid particles, N / m 3 .

[0043] Compared with the prior art, the beneficial effects of the present application are as follows:

[0044] 1. The present application simultaneously considers normal operation and well shut-down operation in drilling operation, i.e. dynamic settling and static settling; in addition, after obtaining the sample liquid density and viscosity uploaded on the measurement system through data acquisition and processing and the control center, the present application controls to proceed to the next step of adjustment, such as adding water or heavy spar and viscosity increasing agent, until the sample liquid reaches the set density and viscosity;

[0045] 2. The present application can completely meet the conditions of set drilling fluid circulation flow rate, drill pipe rotation speed and wellbore angle in static and dynamic drilling fluid barite settling; the barite settling state can be observed through the wellbore made of acrylic material, and the specific settling progress can be read through the horizontal and vertical scales, in addition, the horizontal scale can be moved along the slide rail to adjust the height;

[0046] 3. When the barite settling effect is remarkable, the pipe string bottom end is often blocked by the accumulated barite, the present application can rotate the wellbore to be inverted through the wellbore angle rotating motor, and rotate the stirring paddle at the bottom of the inner cylinder to make the accumulated barite at the bottom move to make the bottom of the inner cylinder unobstructed;

[0047] 4. The present application can establish a model through a model establishment system for each group of experimental data, and the model establishment system can continuously improve the related format and coefficients of the established mathematical model based on the experimental data obtained in the experimental device, and predict the drilling fluid density. BRIEF DESCRIPTION OF DRAWINGS

[0048] Figure 1 is a structural schematic view of the device of the present application;

[0049] Figure 2 is a structural schematic view of the wellbore mentioned in the present application;

[0050] In the above figure: electromagnetic flowmeter 1, mud tank 2, agitator 3, thickening agent tank 4, viscosity instrument 5, inner cylinder rotating motor 6, first density meter 7, second density meter 8, horizontal scale slide rail 9, fourth density meter 10, stirring paddle 11, first electronic valve 12, third density meter 13, horizontal scale 14, wellbore angle rotating motor 15, wellbore 16, vertical scale 17, data acquisition processing and control center 18, screw pump 19, second electronic valve 20, wellbore mounting frame 21, and inner cylinder 16.1. DETAILED DESCRIPTION

[0051] The preferred embodiments of the present application are described below in conjunction with the accompanying drawings, and it should be understood that the preferred embodiments described herein are only used to explain and illustrate the present application, and are not used to limit the present application.

[0052] Example 1, refer to Figure 1 and Figure 2 The drilling fluid density measuring device considering the influence of barite settling rate mentioned in the present application comprises an electromagnetic flowmeter 1, a mud tank 2, an agitator 3, a thickening agent tank 4, a viscosity instrument 5, an inner cylinder rotating motor 6, a first density meter 7, a second density meter 8, a horizontal scale slide rail 9, a fourth density meter 10, a stirring paddle 11, a first electronic valve 12, a third density meter 13, a horizontal scale 14, a wellbore angle rotating motor 15, a wellbore 16, a vertical scale 17, a data acquisition processing and control center 18, a screw pump 19, a second electronic valve 20, a wellbore mounting frame 21, and an inner cylinder 16.1. The lower end of the mud tank 2 is connected to the screw pump 19 through the second electronic valve 20, the inner cavity of the mud tank 2 is provided with the agitator 3, the upper side of the mud tank 2 is connected to the thickening agent tank 4 through a pipeline, and the middle part of the mud tank 2 is connected to the viscosity instrument 5 through a pipeline. The wellbore mounting frame 21 is installed on one side of the mud tank 2, the wellbore 16 is installed on the wellbore mounting frame 21, the middle part of the wellbore 16 is adjusted in inclination angle by the wellbore angle rotating motor 15, the inner cylinder 16.1 for simulating a drill string is installed in the inner cavity of the wellbore 16, the top of the inner cylinder 16.1 is provided with the inner cylinder rotating motor 6, the first electronic valve 12 is installed on one side of the bottom of the inner cylinder 16.1, the outlet of the first electronic valve 12 is connected to the mud tank 2 through a pipeline, the top of the inner cylinder 16.1 is connected to the output end of the screw pump 19 through a pipeline, and the inner cylinder 16.1 is provided with the first density meter 7, the second density meter 8, the third density meter 13, and the fourth density meter 10 at equal intervals from top to bottom. The thickening agent tank 4, the viscosity instrument 5, the inner cylinder rotating motor 6, the wellbore angle rotating motor 15, and the screw pump 19 are respectively connected to the data acquisition processing and control center 18 through control lines.

[0053] Among them, the inner cavity of the inner cylinder 16.1 is provided with the stirring paddle 11, one side of the stirring paddle 11 is provided as an outlet, and the first electronic valve 12 is installed at the outlet.

[0054] The axial direction of the wellbore 16 is provided with a vertical scale 17, the radial direction is provided with a horizontal scale 14, and the horizontal scale 14 is arranged on the horizontal scale slide rail 9.

[0055] The horizontal scale slide rail 9 is axially arranged on the outer wall of the wellbore 16, the outer end of the horizontal scale 14 is sleeved on the horizontal scale slide rail 9, and the position of the horizontal scale 14 is moved up and down along the horizontal scale slide rail 9.

[0056] The wellbore angle rotating motor 15 is arranged in the middle of the wellbore mounting frame 21, the output end of the wellbore angle rotating motor 15 is connected to the middle of the wellbore 16, the wellbore 16 is driven to have a certain inclination angle through the rotation of the wellbore angle rotating motor 15, and different inclination angle inclined shafts are simulated.

[0057] The electromagnetic flowmeter 1 is arranged on the pipeline between the output end of the screw pump 19 and the inner cylinder 16.1.

[0058] Four measuring points are arranged on the inner cylinder 16.1 of the wellbore 16 at equal intervals to measure the density change of the barite sample liquid to obtain the barite settling rate data, and a mathematical model of the density of the barite sample liquid at a certain depth with respect to different densities, viscosities and barite particle sizes is established, and the specific process is as follows:

[0059] (1.1)

[0060] In the formula, ρ represents the density of the barite sample liquid, g / cm 3 ; ρ0 represents the initial density of the sample liquid, g / cm 3 ; μ represents the viscosity, mPa·s; t represents the time, min; d represents the diameter of the barite, 10 -5 m; h represents the depth from the pipe mouth, m; a and b represent the fitting correlation coefficients, dimensionless.

[0061] The test method of the drilling fluid density measuring device considering the influence of the barite settling rate comprises the following steps:

[0062] S1, cleaning the experimental device: the entire pipeline and the mud tank 2 are cleaned 2-3 times by using clean water through a circulating system;

[0063] S2, preparing the experimental sample liquid: first, calculate the approximate amount of water and barite needed for the experiment, then inject the water into the mud tank 2, set the highest speed and open the stirrer 3 and screw pump 19; then add barite and viscosity enhancer to the mud tank 2 at a constant speed, after stirring and circulating for a sufficient time at the highest speed, read the sample liquid density and viscosity in the data acquisition and processing and control center 18, control the next step of preparation by reading the sample liquid density and viscosity, such as adding water or adding barite and viscosity enhancer, until the set density and viscosity are reached;

[0064] S3, settling experiment: control the required wellbore inclination angle, inner cylinder rotation speed and mud circulation flow rate through the data acquisition and processing and control center 18, during the static settling experiment, the data acquisition and processing and control center 18 controls the closure of the first electronic valve 12 or the second electronic valve 20 and the stop of the circulation system; see the curve of the readings of each densimeter changing with time, and the real-time readings of each densimeter are transmitted to the model establishment system through the information acquisition card;

[0065] S4, calculating the barite content reduction rate: the density values ρ i,t measured at different times at each measuring point i，t can be used to calculate the barite content η i，t at measuring point i, the calculation formula is as follows:

[0066] (1.2)

[0067] In the formula: ρ i,t is the density value measured at different times at each measuring point, g / cm 3 ; η i，t is the barite content at measuring point i; ρ 重晶石 is the initial density of the barite sample liquid, g / cm 3 ;

[0068] S5, at the end of the experiment, the experimental sample liquid in the mud tank 2 is discharged and clean water is injected, the experimental sample liquid in the pipeline and wellbore 16 is displaced with clean water, and this process is repeated 3-5 times, and the power is turned off.

[0069] Specifically, in the above step S4,

[0070] the theoretical time required for sufficient settling is calculated by continuing to use the relationship between the settling velocity of barite particles in still or flowing liquid and the length of the pipe column, formula (1.2), and the experiment is verified by comparing the theoretical time length with the actual settling time;

[0071] (1.3)

[0072] In the formula: u tSettling velocity, m / s; L Column length, m; T Predicted settling time, min;

[0073] Force analysis of solid particles in liquid shows that the solid particles are affected by their own gravity and the buoyancy of the liquid. Through analysis, the formula for calculating the settling velocity of particles in static liquid is obtained, as shown in equation (1.3).

[0074] (1.4)

[0075] In the formula: u t Settling velocity, m / s; C d Resistance coefficient, dimensionless; V Specific gravity of liquid, N / cm 3 ; V S Specific gravity of solid particles, N / m 3 ;

[0076] When the Reynolds number Re is less than 1, the relative motion between the particles and the liquid belongs to laminar flow. The resistance coefficient C d of the spherical solid particles in the laminar flow zone and the free settling velocity formula of the solid particles are respectively:

[0077] (1.5)

[0078] (1.6)

[0079] In the formula: u t Settling velocity, m / s; C d Resistance coefficient, dimensionless; p Fluid density, kg / m 3 ; p s Solid particle density, kg / m 3 ; mu Fluid dynamic, mPa·s; d Solid particle diameter, m;

[0080] When the Reynolds number is 1<Re<1000, it is called transition zone settling, which represents the gradually developed turbulence in the movement of solid particles. The resistance coefficient is

[0081] (1.7)

[0082] In the formula: u t Settling velocity, m / s; C d Resistance coefficient, dimensionless; p Fluid density, kg / m 3 ; mu Fluid dynamic;

[0083] Substitute equation (1.6) into equation (1.4). Through calculation, the free settling velocity u t of spherical particles in the transition flow zone can be obtained.

[0084] When the Reynolds number is 1000<Re<2x10', it is called turbulent zone sedimentation, which describes the fully developed flow except the boundary layer, and the resistance coefficient of the spherical solid particles is close to a constant C when the spherical solid particles are in turbulent sedimentation d ≈0.45,

[0085] C d ≈0.45 is brought into formula (1.4), and the free sedimentation velocity of the solid particles is calculated as formula (1.7):

[0086] (1.8)

[0087] In the formula, u t Sedimentation velocity, m / s; d Diameter of solid particles, m; V Specific weight of liquid, N / cm 3 ; V S Specific weight of solid particles, N / m 3 .

[0088] Embodiment 2, the application discloses a drilling fluid density measuring device considering the influence of barite sedimentation rate, and the technical scheme is as follows: a mud tank 2, a stirrer 3, a viscosity agent tank 4, a viscosity instrument 5, an inner cylinder rotating motor 6, a first electronic valve 12, a well shaft angle rotating motor 15, a well shaft 16, a data acquisition processing and control center 18, a screw pump 19, a second electronic valve 20 and a well shaft mounting frame 21 are arranged, the lower end of the mud tank 2 is connected with the screw pump 19 through the second electronic valve 20, the inner cavity of the mud tank 2 is provided with the stirrer 3, the upper side of the mud tank 2 is connected with the viscosity agent tank 4 through a pipeline, and the middle part of the mud tank 2 is connected with the viscosity instrument 5 through a pipeline; the well shaft mounting frame 21 is arranged on one side of the mud tank 2, the well shaft 16 is arranged on the well shaft mounting frame 21, the middle part of the well shaft 16 is provided with the well shaft angle rotating motor 15 to adjust the inclination angle, the inner cylinder 16.1 for simulating a drill string is arranged in the inner cavity of the well shaft 16, the top of the inner cylinder 16.1 is provided with the inner cylinder rotating motor 6, the first electronic valve 12 is arranged on one side of the bottom of the inner cylinder 16.1, the outlet of the first electronic valve 12 is connected with the mud tank 2 through a pipeline, and the top of the inner cylinder 16.1 is connected with the output end of the screw pump 19 through a pipeline; the viscosity agent tank 4, the viscosity instrument 5, the inner cylinder rotating motor 6, the well shaft angle rotating motor 15 and the screw pump 19 are respectively connected with the data acquisition processing and control center 18 through control lines.

[0089] The difference between the embodiment 1 and the embodiment 2 is that:

[0090] The inner cylinder 16.1 is provided with six groups of density meters arranged at equal intervals from top to bottom, so that the density data can be better obtained.

[0091] The above merely describes some preferred embodiments of the present application, and any skilled person in the art can modify the above-described technical solutions or modify them into equivalent technical solutions. Therefore, the corresponding simple modifications or equivalent transformations according to the technical solutions of the present application are within the scope of the present application.

Claims

1. A drilling fluid density measuring device that takes into account the effect of barite settling rate, characterized by: The mud tank (2) is connected with the screw pump (19) through the second electronic valve (20) at the lower end, the inner cavity of the mud tank (2) is provided with the agitator (3), the upper side of the mud tank (2) is connected with the thickening agent tank (4) through a pipeline, and the middle part of the mud tank (2) is connected with the viscosity instrument (5) through a pipeline; the well shaft mounting frame (21) is mounted on one side of the mud tank (2), the well shaft (16) is mounted on the well shaft mounting frame (21), the middle part of the well shaft (16) is adjusted in the inclination angle through the well shaft angle rotating motor (15), the inner cylinder (16.1) for simulating the drill string is mounted in the inner cavity of the well shaft (16), the top of the inner cylinder (16.1) is provided with the inner cylinder rotating motor (6), the first electronic valve (12) is mounted on one side of the bottom of the inner cylinder (16.1), the outlet of the first electronic valve (12) is connected with the mud tank (2) through a pipeline, the top of the inner cylinder (16.1) is connected with the output end of the screw pump (19) through a pipeline, and the first density meter (7), the second density meter (8), the third density meter (13) and the fourth density meter (10) are mounted on the inner cylinder (16.1) at equal intervals from top to bottom; the thickening agent tank (4), the viscosity instrument (5), the inner cylinder rotating motor (6), the well shaft angle rotating motor (15) and the screw pump (19) are connected with the data acquisition processing and control center (18) through control lines.

2. The drilling fluid density measuring device that takes into account the effect of barite settling rate according to claim 1, characterized in that: The inner cavity of the inner cylinder (16.1) is provided with the agitator blade (11), one side of the agitator blade (11) is provided with an outlet, and the first electronic valve (12) is mounted at the outlet.

3. The drilling fluid density measuring device that accounts for the impact of barite settling rate of claim 2, wherein: The vertical scale (17) is mounted on the axial direction of the well shaft (16), and the horizontal scale (14) is mounted on the radial direction and is mounted on the horizontal scale sliding rail (9).

4. The drilling fluid density measuring device that takes into account the effect of barite settling rate according to claim 3, characterized in that: The horizontal scale sliding rail (9) is axially mounted on the outer wall of the well shaft (16), the outer end of the horizontal scale (14) is sleeved on the horizontal scale sliding rail (9) and moves up and down along the horizontal scale sliding rail (9).

5. The drilling fluid density measuring device that takes into account the effect of barite settling rate according to claim 4, characterized in that: The well shaft angle rotating motor (15) is mounted on the middle part of the well shaft mounting frame (21), the output end of the well shaft angle rotating motor (15) is connected with the middle part of the well shaft (16), the well shaft (16) is driven to have a certain inclination angle through the rotation of the well shaft angle rotating motor (15), and the inclined shaft with different inclination angles is simulated.

6. The drilling fluid density measuring device that takes into account the effect of barite settling rate according to claim 5, characterized in that: The electromagnetic flowmeter (1) is mounted on the pipeline between the output end of the screw pump (19) and the inner cylinder (16.1).

7. The drilling fluid density measuring device that accounts for the impact of barite settling rate according to claim 6, wherein: Four measuring points are arranged equidistantly on the inner cylinder (16.1) of the wellbore (16) to measure the density change of the barite sample liquid to obtain the barite settling rate data, and a mathematical model about the density of the barite sample liquid at a certain depth under different densities, viscosities and barite particle sizes is established, which is as follows: （1.1） where: p represents the density of the barite sample liquid, g / cm 3 ; p0 represents the initial density of the sample liquid, g / cm 3 ; μ represents the fluid dynamicity, mPa·s; t represents time, min; d represents the diameter of the solid particles, 10 -5 m; h represents the depth from the pipe mouth, m; a, b represent the correlation coefficients obtained by fitting, dimensionless.

8. The method of testing a drilling fluid density measuring device that accounts for the impact of barite settling rate of claim 7, wherein The method comprises the following steps: S1, cleaning the experimental device: the entire pipeline and the mud tank (2) are cleaned 2-3 times by circulating system using clean water; S2, preparing the experimental sample liquid: first, calculate the approximate amount of water and barite required for the experiment, then inject water into the mud tank (2), set the highest speed, and open the stirrer (3) and the screw pump (19); then add barite and viscosity enhancer to the mud tank (2) at a uniform speed, after stirring and circulating for a sufficient time at the highest speed, read the sample liquid density and viscosity in the data acquisition and processing control center (18), and control the next step of preparation by reading the sample liquid density and viscosity, add water or barite and viscosity enhancer until the set density and viscosity are reached; S3, settling experiment: control the required wellbore inclination angle, inner cylinder rotation speed and mud circulation flow rate through the data acquisition and processing control center (18), in the static settling experiment, the data acquisition and processing control center (18) controls the closure of the first electronic valve (12) or the second electronic valve (20) and the stop of the circulating system; observe the curve of the readings of each densimeter changing with time, and the real-time readings of each densimeter are transmitted to the model establishment system through the information acquisition card; S4, calculate the rate of decrease of barite content: through the density values ρ measured at different times at each measuring point i,t The barite content η at the corresponding measuring point i can be calculated i，t The calculation formula is as follows: （1.2） wherein: p i,t represents the density value measured at different times for each measuring point, g / cm 3 ; η i，t represents the barite content at measuring point i; p 重晶石 represents the initial density of the barite sample liquid, g / cm 3 ; S5, after the experiment, the experimental sample liquid in the mud tank (2) is discharged and clean water is injected, the experimental sample liquid in the pipeline and the wellbore (16) is displaced using clean water, and this process is repeated 3-5 times, and the power is turned off.

9. The method of testing drilling fluid density measuring devices that take into account the effect of barite settling rate according to claim 8, characterized in that: In step S4, Continue to calculate the theoretical time required for full settling through the relationship between the settling speed of barite particles in static or flowing liquid and the length of the pipe column, formula (1.2), and compare the theoretical time length with the actual settling time to verify the experiment; （1.3） wherein: u t represents the settling velocity, m / s; L represents the column length, m; T represents the predicted settling time, min; Through force analysis of solid particles in liquid, it can be known that the solid particles are affected by their own gravity and the buoyancy of the liquid, and the settling speed calculation formula of the particles in static liquid is obtained, as shown in formula (1.3); （1.4） where: u t represents the settling velocity, m / s; C d represents the drag coefficient, dimensionless; V represents the specific weight of the liquid, N / cm 3 ; V S represents the specific weight of the solid particles, N / m 3 ; When the Reynolds number Re is less than 1, the relative movement between the particle and the liquid belongs to laminar flow, and the resistance coefficient C d and the free settling velocity formula of the solid particle are respectively: （1.5） （1.6） wherein: u t represents the settling velocity, m / s; C d represents the drag coefficient, dimensionless; p represents the fluid density, kg / m 3 ; ρ s represents the solid particle density, kg / m 3 ; μ represents the fluid dynamicity, mPa-s; d represents the solid particle diameter, m; When the Reynolds number is 1<Re<1000, it is called transition zone settling, which represents the gradually developed turbulence in the movement of solid particles, and the resistance coefficient is （1.7） wherein: u t represents the settling velocity, m / s; C d represents the drag coefficient, dimensionless; p represents the fluid density, kg / m 3 ; μ represents the fluid dynamic Substituting equation (1.6) into equation (1.4), the free settling velocity of the spherical particles in the transition regime can be obtained by calculation t , When the Reynolds number is 1000 < Re < 2 x 107, it is called turbulent settling, which describes the fully developed flow except for the boundary layer. The drag coefficient of the spherical solid particles is close to a constant C when they are in turbulent settling d ≈ 0.45, C d ≈0.45 into equation (1.4), the free settling velocity of the solid particles is calculated as shown in equation (1.7): （1.8） wherein: u t represents the settling velocity, m / s; d represents the diameter of the solid particles, m; V represents the specific weight of the liquid, N / cm 3 ; V S represents the specific weight of the solid particles, N / m 3 .

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