A method for predicting sand settling velocity in crude oil

Abstract

The application provides a method for predicting the settling velocity of sand particles in crude oil. The method comprises: obtaining a settling velocity model; wherein the settling velocity model is a calculation model of the settling velocity based on the density of sand particles, the density of oil products, and the viscosity of oil products; obtaining the target density of sand particles, the target density of oil products, and the target viscosity of oil products; and determining the settling velocity of target sand particles in the target oil product based on the target density of sand particles, the target density of oil products, and the target viscosity of oil products by using the settling velocity model. The method for predicting the settling velocity of sand particles in crude oil provided by the application can quickly, accurately and conveniently predict the settling velocity of sand particles in crude oil including heavy oil, and solves the problem that the settling velocity of sand particles in crude oil (especially in heavy oil) is difficult to determine, thereby providing a reference for the determination of the minimum flow rate of a gathering pipeline, the cleaning cycle, and the design of a separator and a settling tank.

Description

Technical Field

[0001] This invention relates to a method for predicting the settling velocity of sand particles in crude oil. Background Technology

[0002] During the extraction of high-viscosity crude oil (such as heavy oil), the formation rock skeleton is often destroyed. For shallow oil-bearing reservoirs with loose lithology, sand production is common. Although downhole sand control is strictly enforced in offshore oil extraction, 0.035%-0.058% (mass%) of sand particles still enter the offshore platform processing system with the high-viscosity crude oil. Onshore oilfields, in order to improve crude oil recovery, the cold sand extraction technology often results in a high sand concentration in the produced fluid. In the early stages of extraction, the sand concentration in the produced fluid can be as high as 44%, and after production stabilizes, the sand concentration in the produced fluid remains at around 5%. Sand particles generated during downhole extraction are carried to the surface by high-viscosity crude oil, causing serious damage to production facilities. Sand carried by heavy oil often leads to sand deposition, sand erosion, and corrosion in gathering and transportation pipelines and equipment. In severe cases, it not only causes blockage of pipelines and equipment but also causes pigging to become stuck and even control valves to fail. This significantly increases the workload and maintenance costs of sand removal for pipelines, separators, and other equipment, affecting the operating efficiency of the crude oil gathering and transportation system. The transportation of crude oil in wellbores and gathering pipelines, as well as its separation in equipment such as separators and settling tanks, inevitably involves the sedimentation process of sand in the direction of gravity. Studying the sedimentation velocity of sand particles in crude oil is of great significance for determining the minimum flow velocity of gathering pipelines, the cleaning cycle, and the optimal size of separators and settling tanks. Summary of the Invention

[0003] To address the problem of determining the settling velocity of sand particles in crude oil (especially heavy oil), this invention provides the following technical solution.

[0004] This invention provides a method for predicting the settling velocity of sand particles in crude oil, wherein the method includes:

[0005] Obtain a settling velocity model; wherein, the settling velocity model is a calculation model of settling velocity based on sand density, oil density and oil viscosity;

[0006] Obtain the target sand particle density, target oil density, and target oil viscosity;

[0007] Based on the target sand particle density, target oil density, and target oil viscosity, the settling velocity of the target sand particles in the target oil is determined using a settling velocity model.

[0008] According to the above-mentioned method for predicting the settling velocity of sand particles in crude oil, preferably, the method for obtaining the settling velocity model includes:

[0009] Multiple sets of single-particle sedimentation experiments were conducted to obtain the sedimentation velocity of single-particles with known particle size and density in simulated oil with known density and viscosity for each set of single-particle sedimentation experiments.

[0010] Based on the known particle size and density of each group of single sand particles in simulated oil with known density and viscosity, a sedimentation velocity model is established.

[0011] More preferably, the method further includes: verifying the accuracy of the established settlement model.

[0012] According to the above-mentioned method for predicting the settling velocity of sand particles in crude oil, preferably, the settling velocity model is established based on the settling velocity of single sand particles with known particle size and density in simulated oil with known density and viscosity, corresponding to each group of single sand particle settling experiments, including:

[0013] Based on the known particle size and density of each group of single-particle sedimentation experiments, a sedimentation velocity model was established for the sedimentation velocity of single-particle sand in simulated oil with known density and viscosity. The drag coefficient Cd and parameter d corresponding to each group of single-particle sedimentation experiments were then determined. * ;in,

[0014]

[0015] In the formula, ρ p Sand particle density (kg / m³) 3 ), ρ l Liquid density (kg / m³) 3 ), d is the particle size of sand (m), g is the acceleration due to gravity (m / s²). 2 μ is the viscosity of the oil (Pa·s), and w is the settling velocity, i.e., the final velocity of the sand particles after stable settling (m / s).

[0016] Based on the drag coefficient Cd and parameter d of each group of single sand grain sedimentation experiments * Determine the drag coefficient Cd and parameter d * Relationship;

[0017] Based on the drag coefficient Cd and parameter d * The relationship, combined with the traction coefficient Cd and the parameter d * expression Establish a settlement velocity model;

[0018] Preferably, the traction coefficient Cd and the parameter d * The relation is: A, B, C, and D are coefficients.

[0019] Based on the above method for predicting the settling velocity of sand particles in crude oil, preferably, white oil is used as the simulated oil.

[0020] Based on the above method for predicting the settling velocity of sand particles in crude oil, preferably, the single sand particle settling experiment is conducted in the following manner:

[0021] Pour simulated oil into a 500mL settling cylinder and overflow it by 100-200mL. Start timing from when the sand particles are put into the settling cylinder with zero initial velocity. Track the time taken for the sand particles to pass through the 500mL, 400mL, 300mL, 200mL, and 100mL marks on the settling cylinder. Determine the average settling velocity of the sand particles between the marks based on the distance between the marks. Take the arithmetic mean of the average settling velocities between the marks as the settling velocity of the sand particles in the entire settling cylinder.

[0022] Based on the above method for predicting the settling velocity of sand particles in crude oil, preferably, the accuracy of the established settling model is verified using the following settling experimental apparatus:

[0023] The sedimentation experimental device includes a separatory funnel with a small cone angle and two outlets. The upper part of the separatory funnel is cylindrical and the lower part is conical. The cone angle of the separatory funnel is 10-30°. The lower part of the separatory funnel has a bottom outlet. A lateral outlet is provided on the upper side wall of the separatory funnel at the connection with the lower part. Switches are provided for the bottom outlet and the lateral outlet. Furthermore, the sedimentation experimental device is further provided with a silicone hose connected to the lateral outlet and a peristaltic pump in contact with the silicone hose, which can promote the discharge of sand-containing simulated oil.

[0024] The separatory funnel of the above-mentioned sedimentation experimental device has the characteristics of small cone angle and dual outlet, which overcomes the problems of interfacial sand adsorption and deposition on the wall of conventional separatory funnel. The sedimentation experimental device of sand particles in crude oil built around the dual-outlet separatory funnel can effectively verify the accuracy of the sedimentation velocity model.

[0025] More preferably, the accuracy of the established settlement model includes:

[0026] (1) Pour water and simulated oil into a small cone-angled double-outlet separatory funnel, with the oil-water interface controlled at a distance of not less than 20 mm above the lateral outlet and the simulated oil column height of at least 150 mm; heat the small cone-angled double-outlet separatory funnel containing water and simulated oil to the target temperature and maintain it constant; predict the settling time corresponding to the settling velocity and settling height (i.e., simulated oil column height) based on the established settling model;

[0027] (2) Under constant temperature conditions, take a single-size sand particle and sprinkle it into the separatory funnel with a small cone angle and start timing. Take samples at the side outlet and bottom outlet of the separatory funnel with a small cone angle and a double outlet at the predicted settling time point, the positive deviation time point of 15-30%, and the negative deviation time point of 15-30% (for example, at the predicted settling time and the positive and negative deviation time points of 20%). For each sampling except the last sampling, if the oil-water interface is lower than the side drain after sampling, inject a small amount of clean water in the reverse direction from the side drain.

[0028] (3) Separate, clean, dry and weigh the sand particles in each sample taken from the side outlet and bottom outlet in step (2);

[0029] (4) Based on the ratio of the weight of sand particles in each sample to the total amount of sand sprinkled, the sand recovery rate at each time point is determined; the ratio of the sum of the sand amount in the samples taken at the positive and negative deviation time points and the predicted time points to the total amount of sand sprinkled is the prediction accuracy of the settling velocity model.

[0030] Based on the above method for predicting the settling velocity of sand particles in crude oil, the preferred settling velocity model is as follows:

[0031]

[0032]

[0033]

[0034] In the formula, ρ p Sand particle density (kg / m³) 3 ), ρ l Liquid density (kg / m³) 3 ), d is the particle size of sand (m), g is the acceleration due to gravity (m / s²). 2 μ is the viscosity of the oil (Pa·s), w is the settling velocity, i.e., the final velocity of the sand particles after stable settling (m / s); A, B, C, and D are coefficients.

[0035] More preferably, the settlement velocity model is:

[0036]

[0037]

[0038]

[0039] In the formula, ρ p Sand particle density (kg / m³) 3 ), ρ l Liquid density (kg / m³) 3 ), d is the particle size of sand (m), g is the acceleration due to gravity (m / s²). 2 μ is the viscosity of the oil (Pa·s), and w is the settling velocity, i.e., the final velocity of the sand particles after stable settling (m / s).

[0040] The aforementioned settling velocity model has high prediction accuracy, simple structure, and convenient calculation, which can provide convenience for relevant practitioners to quickly and accurately predict the settling velocity of sand particles in crude oil.

[0041] The beneficial effects of this invention are: the method for predicting the settling velocity of sand particles in crude oil provided by this invention can quickly, accurately and conveniently predict the settling velocity of sand particles in crude oil, including heavy oil, and solve the problem that the settling velocity of sand particles in crude oil is difficult to determine. It provides a reference for determining the minimum flow rate of gathering and transportation pipelines, the cleaning cycle, and the design of separators and settling tanks. Attached Figure Description

[0042] Figure 1 This is a schematic diagram of the first sedimentation test apparatus used in Example 1.

[0043] Figure 2 This is a schematic diagram of the second sedimentation experimental apparatus used in Example 2. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0045] To explore the settling velocity of sand particles in crude oil, a specific embodiment of the present invention provides a method for predicting the settling velocity of sand particles in crude oil, wherein the method includes:

[0046] Step S1: Obtain the settling velocity model; wherein, the settling velocity model is a calculation model of settling velocity based on sand density, oil density and oil viscosity;

[0047] Step S2: Obtain the target sand particle density, target oil density, and target oil viscosity;

[0048] Step S3: Based on the target sand particle density, target oil density, and target oil viscosity, determine the settling velocity of the target sand particles in the target oil using a settling velocity model.

[0049] In one embodiment, step S1, obtaining the settlement velocity model includes:

[0050] Step S11: Conduct multiple sets of single sand grain sedimentation experiments to obtain the sedimentation velocity of single sand grains with known particle size and density in simulated oil with known density and viscosity corresponding to each set of single sand grain sedimentation experiments.

[0051] Step S12: Based on the known particle size and density of each group of single sand particles in simulated oil with known density and viscosity, establish a sedimentation velocity model;

[0052] Further, step S1, obtaining the settlement velocity model, further includes:

[0053] Step S13: Verify the accuracy of the established settlement model.

[0054] In one embodiment, step S12, establishing a settling velocity model based on the settling velocity of single sand particles with known particle size and density in simulated oil with known density and viscosity corresponding to each group of single sand particle settling experiments, includes:

[0055] Step S121: Based on the known particle size and density of each group of single sand grains in simulated oil with known density and viscosity, establish a settling velocity model and determine the drag coefficient Cd and parameter d corresponding to each group of single sand grain settling experiments. * ;in,

[0056]

[0057] In the formula, ρ p Sand particle density (kg / m³) 3 ), ρ l Liquid density (kg / m³) 3 ), d is the particle size of sand (m), g is the acceleration due to gravity (m / s²). 2 μ is the viscosity of the oil (Pa·s), and w is the settling velocity, i.e., the final velocity of the sand particles after stable settling (m / s).

[0058] Step S122: Based on the drag coefficient Cd and parameter d corresponding to the single sand grain settling experiments of each group * Determine the drag coefficient Cd and parameter d * Relationship;

[0059] Based on the drag coefficient Cd and parameter d * The relationship, combined with the traction coefficient Cd and the parameter d * expression Establish a settlement velocity model;

[0060] Furthermore, the traction coefficient Cd and the parameter d * The relation is: A, B, C, and D are coefficients.

[0061] In one embodiment, the settlement velocity model is as follows:

[0062]

[0063]

[0064]

[0065] In the formula, ρ pSand particle density (kg / m³) 3 ), ρ l Liquid density (kg / m³) 3 ), d is the particle size of sand (m), g is the acceleration due to gravity (m / s²). 2 μ is the viscosity of the oil (Pa·s), w is the settling velocity, i.e., the final velocity of the sand particles after stable settling (m / s); A, B, C, and D are coefficients.

[0066] Furthermore, the settlement velocity model is as follows:

[0067]

[0068]

[0069]

[0070] In the formula, ρ p Sand particle density (kg / m³) 3 ), ρ l Liquid density (kg / m³) 3 ), d is the particle size of sand (m), g is the acceleration due to gravity (m / s²). 2 μ is the viscosity of the oil (Pa·s), and w is the settling velocity, i.e., the final velocity of the sand particles after stable settling (m / s).

[0071] The aforementioned settling velocity model has high prediction accuracy, simple structure, and convenient calculation, which can provide convenience for relevant practitioners to quickly and accurately predict the settling velocity of sand particles in crude oil.

[0072] The Brown-Lawlerye model is the most widely used settling velocity model in existing technologies. Although this settling velocity model has high accuracy in predicting the settling process of sand particles in liquid, the drag coefficient C... d With the Reynolds number Re of sand grains p It is an implicit relationship, requiring continuous trial and error iterations during the determination of sand particle settling velocity, a process that is extremely tedious. The inventors obtained the sand particle settling velocity through single-particle settling experiments. Given the known sand particle size, data analysis revealed that C... d With d * 3 In the Brown-Lawlerye model, C d With Re p Similar relationships, among which

[0073] In the formula ρ p Sand particle density (kg / m³) 3 ), ρ l Liquid density (kg / m³) 3), d is the sand particle size (m), w is the final velocity of the particle after stable settling (m / s), and g is the acceleration due to gravity (m / s²). 2 μ is the viscosity of the oil (Pa·s). Based on this, the relationship of undetermined coefficients is established. In the formula, A, B, C, and D are all undetermined constants. Based on single sand grain settling experimental data and nonlinear regression processing, the values ​​of A, B, C, and D are determined; thus, a dimensionless explicit settling velocity model for sand grains can be obtained. in, Given the particle size of the sand and the properties of the oil, the natural settling velocity of the sand in the oil can be determined.

[0074] In one embodiment, since crude oil is opaque and not conducive to observing the movement of sand particles in crude oil, transparent white oil is selected instead of crude oil as a simulated oil for single sand particle sedimentation experiments.

[0075] In one embodiment, step S11, the single sand grain sedimentation experiment is conducted in the following manner:

[0076] Pour simulated oil into a 500mL settling cylinder and overflow it by 100-200mL. Start timing from when the sand particles are put into the settling cylinder with zero initial velocity. Track the time taken for the sand particles to pass through the 500mL, 400mL, 300mL, 200mL, and 100mL marks on the settling cylinder. Determine the average settling velocity of the sand particles between the marks based on the distance between the marks. Take the arithmetic mean of the average settling velocities between the marks as the settling velocity of the sand particles in the entire settling cylinder.

[0077] In one embodiment, step S13, verifying the accuracy of the established settlement model, is performed using the following settlement test apparatus:

[0078] The sedimentation experimental device includes a separatory funnel with a small cone angle and two outlets. The upper part of the separatory funnel is cylindrical and the lower part is conical. The cone angle of the separatory funnel is 10-30°. The lower part of the separatory funnel has a bottom outlet. A side outlet is provided on the upper side wall of the separatory funnel at the connection with the lower part. Switches are provided for the bottom outlet and the side outlet. Furthermore, the sedimentation experimental device is further provided with a silicone hose connected to the side outlet and a peristaltic pump in contact with the silicone hose, which can promote the discharge of sand-containing simulated oil.

[0079] The high viscosity of oil and the large cone angle of conventional separatory funnels easily lead to the adhesion and deposition of sand particles on the variable-diameter wall. Although oil-water stratification facilitates the discharge of sand particles from the lower aqueous phase through the drain outlet, the presence of interfacial tension causes sand particles to easily adhere to the oil-water interface. Based on this, the inventors developed the aforementioned separatory funnel with a small cone angle and dual outlets. The separatory funnel of the aforementioned sedimentation experimental device features a small cone angle and dual outlets, overcoming the problems of interfacial sand particle adsorption and deposition on the walls of conventional separatory funnels. The sedimentation experimental device for sand particles in crude oil built around this dual-outlet separatory funnel can effectively verify the accuracy of the sedimentation velocity model and can provide a reference for the design of separators and settling tanks.

[0080] In one embodiment, the verification of the accuracy of the established settlement model includes:

[0081] (1) Pour water and simulated oil into a small cone-angled double-outlet separatory funnel, with the oil-water interface controlled at a distance of not less than 20 mm above the lateral outlet and the simulated oil column height of at least 150 mm; heat the small cone-angled double-outlet separatory funnel containing water and simulated oil to the target temperature and maintain it constant; predict the settling time corresponding to the settling velocity and settling height (i.e., simulated oil column height) based on the established settling model;

[0082] (2) Under constant temperature conditions, take a single-size sand particle and sprinkle it into the separatory funnel with a small cone angle and start timing. Take samples at the side outlet and bottom outlet of the separatory funnel with a small cone angle and a double outlet at the predicted settling time point, the positive deviation time point of 15-30%, and the negative deviation time point of 15-30% (for example, at the predicted settling time and the positive and negative deviation time points of 20%). For each sampling except the last sampling, if the oil-water interface is lower than the side drain after sampling, inject a small amount of clean water in the reverse direction from the side drain.

[0083] (3) Separate, clean, dry and weigh the sand particles in each sample taken from the side outlet and bottom outlet in step (2);

[0084] (4) Based on the ratio of the weight of sand particles in each sample to the total amount of sand sprinkled, the sand recovery rate at each time point is determined; the ratio of the sum of the sand amount in the samples taken at the negative deviation time point and the predicted time point to the total amount of sand sprinkled is the prediction accuracy of the settling velocity model.

[0085] In one embodiment, since crude oil is opaque and the sedimentation process of sand particles cannot be tracked, transparent white oil is used instead of crude oil as a simulated oil to verify the accuracy of the established sedimentation model.

[0086] Example 1

[0087] This embodiment provides a method for predicting the settling velocity of sand particles in crude oil, wherein the method includes:

[0088] 1. Obtain the settling velocity model; wherein, the settling velocity model is a calculation model of settling velocity based on sand density, oil density, and oil viscosity; specifically including:

[0089] 1.1 Conduct multiple sets of single-grain sedimentation experiments to obtain the sedimentation velocity of single grains with known particle size and density in simulated oil with known density and viscosity for each set of single-grain sedimentation experiments.

[0090] Three types of white oil (10#, 100#, and 500#) were used as simulated oils in the experiment. The properties of the oils are shown in Table 1.

[0091] Table 1 Properties of Simulated Oil and Target Oil

[0092]

[0093]

[0094] Single sand grain sedimentation test uses, for example Figure 1 The first settling experiment device A shown is used for the test. The first settling experiment device A includes a settling cylinder A1, a high-speed camera A2, and a computer A3.

[0095] Specifically, the single sand grain sedimentation experiment was conducted in the following manner:

[0096] The simulated oil was poured into a 500mL settling cylinder A1, overflowing the 500mL mark by 100-200mL. A high-speed camera A2 was used to record the settling sand particles (100 frames). Timing started from when the sand particles were put into the settling cylinder A1 with zero initial velocity. After the experiment, the post-processing software in the computer A3 was used to track the time taken for the sand particles to pass through the 500mL, 400mL, 300mL, 200mL, and 100mL marks of the settling cylinder A1. Based on the distance (50mm) between the marks, the average settling velocity of the sand particles between the four marks was determined, and the arithmetic mean of the four average velocities was taken as the settling velocity of the sand particles in the entire settling cylinder A1. The sand particle size and the measured settling velocity involved in the single sand particle settling experiment in high-viscosity white oil are shown in Table 2.

[0097] Table 2 Settling velocity of sand particles of different sizes in simulated oil

[0098]

[0099]

[0100] 1.2. Based on the known particle size and density of each group of single sand particles in simulated oil with known density and viscosity, a sedimentation velocity model is established.

[0101] Based on the known particle size and density of each group of single-particle sedimentation experiments, a sedimentation velocity model was established for the sedimentation velocity of single-particle sand in simulated oil with known density and viscosity. The drag coefficient Cd and parameter d corresponding to each group of single-particle sedimentation experiments were then determined. * ;in,

[0102]

[0103] In the formula, ρ p Sand particle density (kg / m³) 3 ), ρ l Liquid density (kg / m³) 3 ), d is the particle size of sand (m), g is the acceleration due to gravity (m / s²). 2 μ is the viscosity of the oil (Pa·s), and w is the settling velocity, i.e., the final velocity of the sand particles after stable settling (m / s).

[0104] Based on the drag coefficient Cd and parameter d of each group of single sand grain sedimentation experiments * Determine the drag coefficient Cd and parameter d * relational formula

[0105] Based on the drag coefficient Cd and parameter d * The relationship, combined with the traction coefficient Cd and the parameter d * expression Establish a settlement velocity model; the settlement velocity model is as follows:

[0106]

[0107]

[0108]

[0109] In the formula, ρ p Sand particle density (kg / m³) 3 ), ρ l Liquid density (kg / m³) 3 ), d is the particle size of sand (m), g is the acceleration due to gravity (m / s²). 2 μ is the viscosity of the oil (Pa·s), and w is the settling velocity, i.e., the final velocity of the sand particles after stable settling (m / s).

[0110] 1.3 Verify the accuracy of the established settlement model.

[0111] The accuracy of the established settlement model was verified using methods such as... Figure 2The second sedimentation experiment was conducted using the second sedimentation experiment apparatus B shown. The second sedimentation experiment apparatus B includes a small-cone angled double-outlet separatory funnel B1, a peristaltic pump B2, a first sampling beaker B3, a second sampling beaker B4, and a silicone tubing B5. The upper part of the small-cone angled double-outlet separatory funnel B1 is cylindrical (diameter 60mm, height 180mm), and the lower part is conical (height 180mm, maximum diameter 60mm). The lower part of the small-cone angled double-outlet separatory funnel B1 has a bottom outlet (diameter 10mm). A connection is provided between the upper and lower parts of the upper sidewall of the small-cone angled double-outlet separatory funnel B1. It has a side outlet (10mm in diameter), and switches are provided for the bottom outlet and the side outlet; the upper part of the separatory funnel B1 with a small conical angle and two outlets has a scale line, with a scale line at the top of 150mm and a scale line at 20mm above the side outlet; the silicone tubing B5 is connected to the side outlet of the separatory funnel B1 with a small conical angle and two outlets, and the peristaltic pump B2 is in contact with the silicone tubing; the second sampling beaker B4 is used to collect the sample taken from the bottom outlet of the separatory funnel B1 with a small conical angle and two outlets; the first sampling beaker B3 is used to collect the sample taken from the side outlet of the separatory funnel B1 with a small conical angle and two outlets.

[0112] The accuracy of the established settlement model was verified in the following ways:

[0113] (1) Pour water and simulated oil (white oil) into a small cone-shaped double-outlet separatory funnel B1, control the oil-water interface at the 0 mark, and control the height of the added heavy oil column to 150 mm; place the small cone-shaped double-outlet separatory funnel B1 containing water and simulated oil into an oven and heat it to the experimental temperature and maintain it constant; predict the sedimentation rate and sedimentation height based on the established sedimentation model and determine the corresponding sedimentation time (as shown in Table 3).

[0114] (2) Screen a number of sand particles of various sizes. Take 0.5g of a single size sand particle each time. Under constant temperature conditions, sprinkle the single size sand particles into the separatory funnel B1 with a small cone angle and start timing. Take samples at the side outlet and bottom outlet of the separatory funnel B1 with a small cone angle and a double outlet at three time points: the predicted settling time point and the positive and negative deviation of 20% (as shown in Table 3). For each sampling except the last sampling, if the oil-water interface is lower than the side drain after sampling, inject a small amount of clean water in the opposite direction from the side drain.

[0115] (3) Each sample taken from the side outlet and bottom outlet in step (2) contains some simulated oil. Diesel oil needs to be added to dilute and reduce the viscosity of the upper oil layer. After mixing and stirring, let it stand at room temperature for 1 hour. Then slowly skim off most of the upper oil layer. Add sufficient degreasing agent and put it into an ultrasonic cleaner for ultrasonic cleaning for 10 minutes. Slowly pour out all the liquid in the beaker. Pour sufficient toluene into the beaker and shake for 3 minutes. Let it stand for 8 hours. Then slowly pour the toluene into the waste liquid bucket. Pour sufficient degreasing agent into the beaker and ultrasonically clean it again for 10 minutes. After ultrasonic cleaning, the oil stains on the surface of the sand particles are basically cleaned. Then rinse with boiling water, filter, dry and weigh.

[0116] (4) Based on the ratio of the weight of sand particles in each sample to the total amount of sand sprinkled, the sand recovery rate at each time point is determined; the ratio of the sum of the sand amount in the samples taken at the -20% time point and the predicted time point to the total amount of sand sprinkled is the prediction accuracy of the settling velocity model.

[0117] Table 3 shows the experimental conditions for gravity settling of sand particles in simulated oil and the mass of sand samples recovered at the predicted time and ±20% deviation time points. For large sand particles of 500 μm, the interval between the predicted time and the ±20% deviation time point is relatively short, so 500 μm sand particles were only sampled at the predicted time point. Table 1 shows that the total amount of sand recovered at the predicted time point (including the sum of the sand sampled at the -20% time point and the predicted time point) in the six experimental groups can be maintained at around 90%, that is, the settling velocity model can achieve a prediction accuracy of 90%.

[0118] Table 3. Gravity settling test conditions, predicted time, and recovered sand volume of sand particles in simulated oil.

[0119]

[0120]

[0121] 2. Obtain the target sand density, target oil density, and target oil viscosity.

[0122] The target oils were 75℃ heavy oil and 90℃ heavy oil, respectively. For specific values, please refer to Table 1.

[0123] 3. Based on the target sand particle density, target oil density, and target oil viscosity, the settling velocity of the target sand particles in the target oil was determined using a settling velocity model. The results are shown in Table 4.

[0124] Table 4 Settlement velocity

[0125] Target oil name Target sand particle size / μm <![CDATA[Target sand grain density / (kg / m 3 )]]> Settlement velocity (mm / s) 90℃ heavy oil 580 2654.71 0.9174 90℃ heavy oil 200 2654.71 0.1091 90℃ heavy oil 100 2654.71 0.0273 75℃ heavy oil 580 2654.71 0.4093 75℃ heavy oil 200 2654.71 0.0487 75℃ heavy oil 100 2654.71 0.0122

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for predicting the settling velocity of sand particles in crude oil, wherein, The method includes: Obtain a settling velocity model; wherein, the settling velocity model is a calculation model of settling velocity based on sand density, oil density and oil viscosity; Obtain the target sand particle density, target oil density, and target oil viscosity; Based on the target sand particle density, target oil density, and target oil viscosity, the settling velocity of the target sand particles in the target oil is determined using a settling velocity model. The settlement velocity model can be determined by including the following steps: Multiple sets of single-particle sedimentation experiments were conducted to obtain the sedimentation velocity of single-particles with known particle size and density in simulated oil with known density and viscosity for each set of single-particle sedimentation experiments. Based on the known particle size and density of each group of single-particle sedimentation experiments, a sedimentation velocity model was established for the sedimentation velocity of single-particle sand in simulated oil with known density and viscosity. The drag coefficient Cd and parameters corresponding to each group of single-particle sedimentation experiments were then determined. ;in, ， In the formula, ρ p The density of the sand particles is kg / m³. ρ l The density of the liquid is kg / m³. d The particle size of the sand is in meters (m). g The acceleration due to gravity is m / s². 2 ; μ The viscosity of the oil is expressed in Pa·s. w Settling velocity is the final velocity of sand particles after they have settled stably, expressed in m / s. Based on the drag coefficient Cd and parameters corresponding to each group of single sand grain sedimentation experiments Determine the drag coefficient Cd and parameters Relationship; Based on the drag coefficient Cd and parameters The relationship, combined with the traction coefficient Cd and parameters expression , Establish a settlement velocity model.

2. The method according to claim 1, wherein, Traction coefficient Cd and parameters The relation is: A, B, C, and D are coefficients.

3. The method according to claim 1, wherein, The acquisition of the settlement velocity model further includes: verifying the accuracy of the established settlement model.

4. The method according to claim 3, wherein, The accuracy of the established settlement model was verified using the following settlement test setup: The sedimentation experimental apparatus includes a separating funnel with a small cone angle and two outlets; the upper part of the separating funnel is cylindrical and the lower part is conical, the cone angle of the separating funnel is 10-30°, the lower part of the separating funnel is provided with a bottom outlet, the upper side wall of the separating funnel is provided with a side outlet at the connection between the lower part and the bottom outlet, and the bottom outlet and the side outlet are provided with switches.

5. The method according to claim 4, wherein, The sedimentation experimental device is further provided with a silicone hose connected to the side outlet and a peristaltic pump in contact with the silicone hose.

6. The method according to claim 4, wherein, The accuracy of the established settlement model, as verified, includes: (1) Pour water and simulated oil into a small cone-angled double-outlet separatory funnel. The oil-water interface is controlled at a distance of not less than 20 mm above the side outlet, and the height of the simulated oil column is at least 150 mm. Heat the small cone-angled double-outlet separatory funnel containing water and simulated oil to the target temperature and keep it constant. Predict the settling time corresponding to the settling velocity and settling height based on the established settling model. (2) Under constant temperature conditions, take a single-size sand particle and sprinkle it into the separatory funnel with a small cone angle and start timing. Take samples at the side outlet and bottom outlet of the separatory funnel with a small cone angle and a double outlet at the predicted settling time point, the positive deviation time point, and the negative deviation time point. For each sampling except the last sampling, if the oil-water interface is lower than the side drain after sampling, inject a small amount of clean water in the opposite direction from the side drain. (3) Separate, clean, dry and weigh the sand particles in each sample taken from the side outlet and bottom outlet in step (2); (4) Based on the ratio of the weight of sand particles in each sample to the total amount of sand sprinkled, the sand recovery rate at each time point is determined; the ratio of the sum of the sand amount in the samples taken at the negative deviation time point and the predicted time point to the total amount of sand sprinkled is the prediction accuracy of the settling velocity model.

7. The method according to any one of claims 1-6, wherein, The settlement velocity model is as follows: In the formula, ρ p The density of the sand particles is kg / m³. ρ l The density of the liquid is kg / m³. d The particle size of the sand is in meters (m). g The acceleration due to gravity is m / s². 2 ; μ The viscosity of the oil is expressed in Pa·s. w is the settling velocity, i.e., the final velocity of the sand particles after stable settling, in m / s; A, B, C, and D are coefficients.

8. The method according to claim 7, wherein, The settlement velocity model is as follows: In the formula, ρ p The density of the sand particles is kg / m³. ρ l The density of the liquid is kg / m³. d The particle size of the sand is in meters (m). g The acceleration due to gravity is m / s². 2 ; μ The viscosity of the oil is expressed in Pa·s. w Settling velocity is the final velocity of sand particles after they have settled stably, expressed in m / s.

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