Method for measuring sand-carrying capacity of emulsion fracturing fluid

Abstract

The invention relates to a method for measuring the sand-carrying capacity of emulsion fracturing fluid. The method comprises the following steps: measuring the apparent density rho of the emulsion fracturing fluid by using a buoyancy type densimeter; measuring the actual density rho 0 of the emulsion fracturing fluid by using a weighing densimeter; the difference value between the apparent density rho of the emulsion fracturing fluid and the actual density rho 0 of the emulsion fracturing fluid is used for representing the sand-carrying capacity of the emulsion fracturing fluid, and the larger the difference value is, the larger the sand-carrying capacity of the emulsion fracturing fluid is. After the measuring method is put into use, the measurement is simple and convenient, the result can be quickly obtained, and the measuring efficiency of the emulsion fracturing fluid on-site measurement of the sand-carrying capacity is improved. And on-site temporary adjustment is facilitated, the fracturing construction stopping time is shortened, and the fracturing construction efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of fracturing technology, specifically relating to a method for determining the sand-carrying capacity of emulsion fracturing fluid. Background Technology

[0002] Emulsion fracturing fluids are a crucial component of fracturing technology. They possess high viscosity, high cross-linking degree, and excellent suspension and stability, playing a vital role in pressure transmission and proppant transport. During fracturing operations, the proppant-carrying capacity of emulsion fracturing fluids under varying flow rates, proppant concentrations, and fluid viscosities directly impacts the distribution of proppant particles and the conductivity of the filled fracture. Good proppant-carrying capacity delivers the proppant to the designated location, forming highly conductive fractures and improving fracturing effectiveness.

[0003] Existing methods for determining the proppant-carrying capacity of emulsion fracturing fluids include the settling rate method, suspension rate method, and temperature and shear resistance method. The settling rate method involves mixing the emulsion fracturing fluid and proppant in a specific ratio, measuring the proppant height (h1) in the emulsion fracturing fluid with a ruler, and then measuring the proppant height (h2) in the emulsion fracturing fluid after a set time (t). The settling rate is then calculated using h1, h2, and t. The method for determining the suspension rate involves mixing a certain mass of proppant (m1) with a certain volume of emulsion fracturing fluid, placing the mixture into a suspension rate testing device, allowing it to stand for a set time, and then separating the proppant from the emulsion fracturing fluid at a set position without disturbance. The proppant in the carrying fluid above the set position is then dried and weighed (m2). The suspension rate is calculated using m1 and m2. The method for determining temperature and shear resistance is to perform the test at a certain temperature for 170 seconds. -1 The viscosity measured by a rheometer after a certain time under shear rate conditions.

[0004] Methods for determining settling rate have long waiting times; methods for determining suspension rate require drying and weighing processes, involving multiple steps and instruments; methods for determining temperature and shear resistance require a rheometer and need to be performed within 170 seconds. -1 Under these conditions, shearing is required, and the shearing time is long. The determination of the proppant-carrying capacity of these three types of emulsion fracturing fluids is inefficient and complex, making it unsuitable for rapid on-site assessment of the proppant-carrying capacity of emulsion fracturing fluids. Summary of the Invention

[0005] The purpose of this invention is to provide a method for determining the sand-carrying capacity of emulsion fracturing fluid, which solves the problems of low efficiency, complex operation, and difficulty in quickly determining the sand-carrying capacity of emulsion fracturing fluid in the field in the prior art.

[0006] To achieve the above objectives, the technical solution adopted by the method for determining the sand-carrying capacity of emulsion fracturing fluid provided by the present invention is as follows:

[0007] The apparent density ρ of the emulsion fracturing fluid is measured using a buoyancy-type densitometer; the actual density ρ0 of the emulsion fracturing fluid is measured using a gravimetric densitometer; the difference between the apparent density ρ and the actual density ρ0 of the emulsion fracturing fluid is used to represent the sand-carrying capacity of the emulsion fracturing fluid. The larger the difference, the greater the sand-carrying capacity of the emulsion fracturing fluid.

[0008] The beneficial effects of this invention are as follows: By using a densitometer to measure the actual density and apparent density of the emulsion fracturing fluid, the difference between the apparent density and the actual density of the emulsion fracturing fluid is used to represent its proppant-carrying capacity. This densitometer measurement method is simple and quick to operate, requiring only two densitometers to measure the actual and apparent densities of the emulsion fracturing fluid, allowing for rapid measurement results. The proppant-carrying capacity of the emulsion fracturing fluid can then be obtained through the difference between the apparent and actual densities. This method enables rapid on-site assessment of the proppant-carrying capacity of the emulsion fracturing fluid, improving the efficiency of on-site proppant-carrying capacity measurement. It also facilitates on-site adjustments, reducing downtime during fracturing operations and improving overall fracturing efficiency. After being put into use, the measurement efficiency of emulsion fracturing fluid has increased by 3 to 40 times, demonstrating significant effectiveness.

[0009] This invention is for testing the sand-carrying capacity of emulsion fracturing fluid at fracturing sites, and is mainly applied in oil and gas extraction technology.

[0010] The emulsion fracturing fluid is a type of fracturing fluid that uses an emulsion thickener.

[0011] To enable rapid characterization of the apparent density of emulsion fracturing fluid and prevent densitometer failure, the buoyancy-type densitometer preferably has a measurement range of 0.8–1.5 g / cm³. 3 .

[0012] To improve the effectiveness and accuracy of the measurement, preferably, the viscosity of the emulsion fracturing fluid is 132–192 mPa·s. Attached Figure Description

[0013] Figure 1 This is a schematic diagram illustrating the measurement of a buoyancy-type density meter in a non-suspended emulsion fracturing fluid according to the implementation method.

[0014] Figure 2 This is a schematic diagram of the forces acting on a buoyancy-type density meter in a suspended emulsion fracturing fluid according to the embodiment.

[0015] Figure 3 This is a schematic diagram illustrating the measurement of the apparent density of emulsion hydraulic fracturing fluid using a buoyancy-type densitometer in the implementation method. Detailed Implementation

[0016] Current methods for determining the sand-carrying capacity of emulsion fracturing fluids, including settling rate, suspension rate, and temperature and shear resistance, are inefficient, complex, and impact on on-site construction progress. Therefore, this invention proposes a hydrometer-based method for determining the sand-carrying capacity of emulsion fracturing fluids. This method uses a buoyancy-type hydrometer to measure the apparent density ρ of the emulsion fracturing fluid and a gravimetric hydrometer to measure the actual density ρ0. The difference between the apparent density ρ and the actual density ρ0 represents the sand-carrying capacity of the emulsion fracturing fluid; the larger the difference, the greater the sand-carrying capacity.

[0017] The technical concept of this invention is as follows: By conducting stress analysis on proppant particles, a method for determining the sand-carrying capacity of emulsion fracturing fluid is derived based on Archimedes' principle. A buoyancy-type hydrometer with an appropriate range is selected to measure the apparent density of the emulsion fracturing fluid, and a weighing-type hydrometer is used to measure the actual density. The difference between the two densities represents the sand-carrying capacity of the emulsion fracturing fluid; the larger the difference, the greater the sand-carrying capacity. The above-mentioned method for determining the sand-carrying capacity of emulsion fracturing fluid using the hydrometer method is simple, quick, and convenient for on-site operation, improving measurement efficiency by 3 to 40 times.

[0018] The method for determining the proppant-carrying capacity of emulsion fracturing fluid in this invention is derived by conducting a stress analysis on the proppant particles in the emulsion fracturing fluid and applying Archimedes' principle. The specific derivation process is as follows:

[0019] 1. Stress Analysis of Proppant in Emulsion Fracturing Fluid

[0020] (1) Stress conditions in emulsion fracturing fluid without suspension

[0021] The hydrometer floats in a fracturing emulsion with no levitation force; the buoyancy force acting on the hydrometer is the theoretical buoyancy force. According to Archimedes' principle:

[0022] Theoretical buoyancy F f The gravity F of the unsuspended emulsion fracturing fluid displaced by the densitometer g1 If in equilibrium, the theoretical buoyancy force F is... f Equal to the gravity F of the hydrometer displacing the unsuspended emulsion fracturing fluid. g1 That is, F g1 =F f That is, we get:

[0023] F f =ρ0V1g(1);

[0024] Among them, F g1 To displace the gravity of the unsuspended emulsion fracturing fluid by the density meter, F f ρ0 is the theoretical buoyancy, V1 is the actual density of the emulsion fracturing fluid, g is the volume of the emulsion fracturing fluid without levitation force displaced by the hydrometer, and g is the acceleration due to gravity.

[0025] A schematic diagram of measurements using a densitometer in a non-suspended emulsion fracturing fluid is shown below. Figure 1 As shown.

[0026] (2) Stress conditions in emulsion fracturing fluid with suspension force

[0027] The hydrometer is suspended in the emulsion fracturing fluid with suspending force. At this point, the buoyancy force on the hydrometer is the resultant force of the theoretical buoyancy and the sand-carrying buoyancy. According to Archimedes' principle:

[0028] The buoyant force acting on the hydrometer, i.e., the theoretical buoyant force F. f And the buoyancy of carrying sand F x The resultant force and the density meter displace the suspending force of the emulsion fracturing fluid F, which has a suspending force. g2 Equilibrium, the specific force diagram is as follows: Figure 2 As shown. Then the theoretical buoyancy F f And the buoyancy of carrying sand F x The resultant force is equal to the weight F of the emulsion fracturing fluid displaced by the hydrometer and having a suspending force. g2 That is, F g2 =F f +F x That is, we get:

[0029] F g2 =F f +F x (2);

[0030] The gravity of the suspended emulsion fracturing fluid displaced by the hydrometer is:

[0031] F g2 =ρV2g (3);

[0032] Among them, F g2 To displace the gravity of the suspended emulsion fracturing fluid by the density meter, F f For theoretical buoyancy, F x ρ is the buoyancy of the sand-carrying fluid, V2 is the apparent density of the emulsion fracturing fluid, V2 is the volume of the emulsion fracturing fluid displaced by the hydrometer with suspending force, and g is the acceleration due to gravity.

[0033] 2. Derivation of the formula for sand-carrying suspension force

[0034] From equations (1), (2), and (3), we can derive:

[0035] F X =F g2 -F f =g(ρV2-ρ0V1) (4);

[0036] Since the diameter of the hydrometer scale is very small, the difference between V1 and V2 is not significant, i.e., V1≈V2, then F x It can be represented as:

[0037] F X =(ρ-ρ0)Vg(5);

[0038] For the same hydrometer, if V g is a constant, then F x It can be represented as:

[0039] F X =ρ-ρ0(6)

[0040] Wherein: F g1 To displace the gravity of the unsuspended emulsion fracturing fluid by the density meter, F g2 To displace the gravity of the suspended emulsion fracturing fluid by the density meter, F f For theoretical buoyancy, F x For sand carrying buoyancy, ρ0 is the actual density of the emulsion fracturing fluid, ρ is the apparent density of the emulsion fracturing fluid, V1 is the volume of emulsion fracturing fluid without suspending force displaced by the hydrometer, V2 is the volume of emulsion fracturing fluid with suspending force displaced by the hydrometer, and g is the acceleration due to gravity.

[0041] In conclusion, F x The buoyancy for carrying sand represents the sand-carrying capacity of the emulsion fracturing fluid. That is, the difference between the apparent density ρ and the actual density ρ0 of the emulsion fracturing fluid represents its sand-carrying capacity. The larger the difference, the greater the sand-carrying capacity of the emulsion fracturing fluid.

[0042] The density of the suspended emulsion fracturing fluid was measured using a hydrometer, and the sand-carrying capacity of the emulsion fracturing fluid was calculated based on the formula derived above. The specific measurement method is as follows:

[0043] (1) Take a certain amount of emulsion fracturing fluid and place it in a container;

[0044] (2) The measurement range is 0.8~1.5g / cm 3 The buoyancy-type density meter remains vertically suspended in the emulsion fracturing fluid, without contacting the container wall, such as... Figure 3 As shown;

[0045] (3) Read the readings of the buoyancy hydrometer and the lowest point of the emulsion fracturing fluid, which is the apparent density ρ of the emulsion fracturing fluid;

[0046] (4) The actual density ρ0 of the emulsion hydraulic fracturing fluid was measured using a gravimetric hydrometer;

[0047] (5) The difference between the apparent density ρ of hydraulic fracturing fluid and the actual density ρ0 of emulsion hydraulic fracturing fluid represents the sand-carrying capacity of emulsion hydraulic fracturing fluid.

[0048] The implementation process of the present invention will be described in detail below with reference to specific embodiments.

[0049] I. Implementation Examples

[0050] Example 1:

[0051] The present invention provides a method for determining the sand-carrying capacity of emulsion fracturing fluid, the specific method being:

[0052] (1) Take 200 mL of emulsion fracturing fluid with a viscosity of 132 mPa·s and place it in a container;

[0053] (2) The measurement range is 0.8~1.5g / cm 3 The buoyancy-type density meter remains vertically suspended in the emulsion fracturing fluid, without contacting the container wall;

[0054] (3) The reading of the buoyancy-type hydrometer at the lowest point of the emulsion fracturing fluid level is 1.098 g / cm³. 3 That is, the apparent density ρ of the emulsion fracturing fluid is 1.098 g / cm³. 3 ;

[0055] (4) The actual density ρ0 of the emulsion fracturing fluid was measured to be 0.998 g / cm³ using a gravimetric hydrometer. 3 ;

[0056] (5) The difference between the apparent density ρ of hydraulic fracturing fluid and the actual density ρ0 of emulsion hydraulic fracturing fluid is 0.1 g / cm³. 3 This indicates the sand-carrying capacity of the emulsion fracturing fluid.

[0057] Example 2:

[0058] The difference between the method for determining the sand-carrying capacity of the emulsion fracturing fluid in Example 2 and that in Example 1 is that the viscosity of the emulsion fracturing fluid is 141 mPa·s.

[0059] (1) Take 200 mL of emulsion fracturing fluid with a viscosity of 141 mPa·s and place it in a container;

[0060] (2) The measurement range is 0.8~1.5g / cm 3 The buoyancy-type density meter remains vertically suspended in the emulsion fracturing fluid, without contacting the container wall;

[0061] (3) The reading of the buoyancy-type hydrometer at the lowest point of the emulsion fracturing fluid level is 1.146 g / cm³. 3 That is, the apparent density ρ1.146 of the emulsion fracturing fluid is g / cm³. 3 ;

[0062] (4) The actual density ρ0 of the emulsion fracturing fluid was measured to be 0.996 g / cm³ using a gravimetric hydrometer. 3 ;

[0063] (5) The difference between the apparent density ρ of hydraulic fracturing fluid and the actual density ρ0 of emulsion hydraulic fracturing fluid is 0.15 g / cm³. 3 This indicates the sand-carrying capacity of the emulsion fracturing fluid.

[0064] Example 3:

[0065] The difference between the method for determining the sand-carrying capacity of the emulsion fracturing fluid in Example 3 and that in Example 1 is that the viscosity of the emulsion fracturing fluid is 165 mPa·s.

[0066] (1) Take 200 mL of emulsion fracturing fluid with a viscosity of 165 mPa·s and place it in a container;

[0067] (2) The measurement range is 0.8~1.5g / cm 3 The buoyancy-type density meter remains vertically suspended in the emulsion fracturing fluid, without contacting the container wall;

[0068] (3) The reading of the buoyancy-type hydrometer at the lowest point of the emulsion fracturing fluid level is 1.195 g / cm³. 3 That is, the apparent density ρ of the emulsion fracturing fluid is 1.195 g / cm³. 3 ;

[0069] (4) The actual density ρ0 of the emulsion fracturing fluid was measured to be 0.995 g / cm³ using a gravimetric hydrometer. 3 ;

[0070] (5) The difference between the apparent density ρ of hydraulic fracturing fluid and the actual density ρ0 of emulsion hydraulic fracturing fluid is 0.2 g / cm³. 3 This indicates the sand-carrying capacity of the emulsion fracturing fluid.

[0071] Example 4:

[0072] The difference between the method for determining the sand-carrying capacity of the emulsion fracturing fluid in Example 4 and that in Example 1 is that the viscosity of the emulsion fracturing fluid is 192 mPa·s.

[0073] (1) Take 200 mL of emulsion fracturing fluid with a viscosity of 192 mPa·s and place it in a container;

[0074] (2) The measurement range is 0.8~1.5g / cm 3 The buoyancy-type density meter remains vertically suspended in the emulsion fracturing fluid, without contacting the container wall;

[0075] (3) The reading of the buoyancy-type hydrometer at the lowest point of the emulsion fracturing fluid level is 1.243 g / cm³. 3 That is, the apparent density ρ of the emulsion fracturing fluid is 1.243 g / cm³. 3 ;

[0076] (4) The actual density ρ0 of the emulsion fracturing fluid was measured to be 0.993 g / cm³ using a gravimetric hydrometer. 3 ;

[0077] (5) The difference between the apparent density ρ of hydraulic fracturing fluid and the actual density ρ0 of emulsion hydraulic fracturing fluid is 0.25 g / cm³. 3This indicates the sand-carrying capacity of the emulsion fracturing fluid.

[0078] II. Comparative Example

[0079] The sand-carrying capacity of the emulsion fracturing fluids involved in Examples 1 to 4 was measured using methods such as settling rate measurement, suspension rate measurement, and temperature and shear resistance measurement.

[0080] Settlement rate measurement method:

[0081] The emulsion fracturing fluid and proppant were mixed evenly at a ratio of 100:30. The height h1 of the proppant in the emulsion fracturing fluid was measured with a ruler. The time t was set to 10 minutes. The height h2 of the proppant in the emulsion fracturing fluid was then measured with a ruler. The settling rate was obtained using h1, h2, and t.

[0082] Methods for determining suspension rate:

[0083] A proppant mass m1 was thoroughly mixed with 400 mL of hydraulic fracturing emulsion and placed in a suspension testing device. After standing for 10 minutes, the proppant was undisturbed and separated from the hydraulic fracturing emulsion at a predetermined position. The proppant in the sand-carrying fluid above the predetermined position was then dried and weighed, yielding a mass m2. The suspension rate was calculated using m1 and m2.

[0084] Methods for determining temperature and shear resistance:

[0085] At 85℃ for 170 seconds -1 Under shear rate conditions, the viscosity of the emulsion fracturing fluid was measured using a rheometer after 120 minutes.

[0086] The results of measuring the sand-carrying capacity of the emulsion fracturing fluid involved in Examples 1-4 using the densitometer method and the methods of sedimentation rate determination, suspension rate determination, and temperature and shear resistance determination are shown in Table 1 below.

[0087] Table 1 Comparison of Measurement Data

[0088]

[0089]

[0090] As shown in Table 1 above, with the increase of the viscosity of the emulsion fracturing fluid, the difference between the apparent density and the actual density of the emulsion fracturing fluid measured by the hydrometer method of the present invention increases, indicating an increase in the sand-carrying capacity of the emulsion fracturing fluid; the settling rate measured by the settling rate method decreases, indicating an increase in the sand-carrying capacity of the emulsion fracturing fluid; the suspension rate measured by the suspension rate method increases, indicating an increase in the sand-carrying capacity of the emulsion fracturing fluid; and the temperature and shear resistance rate measured by the temperature and shear resistance method increases, indicating an increase in the sand-carrying capacity of the emulsion fracturing fluid. Therefore, the sand-carrying capacity of the emulsion fracturing fluid obtained by the hydrometer method of the present invention is consistent with the measurement methods of settling rate, suspension rate, and temperature and shear resistance.

[0091] Compared to methods for measuring settling rate, suspension rate, and temperature and shear resistance, the densitometer method of this invention takes significantly less time. Compared to methods for measuring settling rate and suspension rate, the densitometer method of this invention is 3 times more efficient; compared to methods for measuring temperature and shear resistance, it is 40 times more efficient. Therefore, the densitometer method of this invention for determining the sand-carrying capacity of emulsion fracturing fluid is simple, quick, and convenient for on-site operation.

[0092] III. Application Examples

[0093] Based on the usage conditions of emulsion fracturing fluids in North China, the standards for the sand-carrying capacity of emulsion fracturing fluids are clarified. For example, the difference between the apparent density and the actual density of the emulsion fracturing fluid should be 0.1. When the difference between the apparent density and the actual density of the emulsion fracturing fluid is greater than or equal to 0.1, it indicates that the sand-carrying capacity of the emulsion fracturing fluid meets the usage requirements. When the difference between the apparent density and the actual density of the emulsion fracturing fluid is less than 0.1, it indicates that the sand-carrying capacity of the emulsion fracturing fluid does not meet the usage requirements. In this case, it is necessary to consider that the insufficient sand-carrying capacity of the emulsion fracturing fluid may be due to factors such as changes in water quality. Then, the concentration of the emulsion thickener should be adjusted to make its sand-carrying capacity meet the usage requirements.

[0094] The actual density and apparent density of the emulsion fracturing fluid are measured using a weighing hydrometer and a buoyancy hydrometer. The difference between the apparent density and the actual density of the emulsion fracturing fluid represents its sand-carrying capacity. Based on the method for determining the sand-carrying capacity of emulsion fracturing fluid according to the present invention, the sand-carrying capacity of the emulsion fracturing fluid can be quickly determined, guiding the smooth progress of on-site construction.

[0095] In summary, the application of this testing method enables rapid results, improving the efficiency of on-site testing of the proppant-carrying capacity of emulsion fracturing fluids. It also facilitates on-site adjustments, reducing downtime during fracturing operations and thus increasing overall fracturing efficiency.

[0096] The above is a detailed description of the embodiments, but it is not intended to limit the technical solutions of the present invention. Those skilled in the art should understand that any modifications, partial substitutions, and variations can be made to the above embodiments within the scope of the present invention, and all such modifications and variations should be covered within the scope of the present invention.

Claims

1. A method for determining the sand-carrying capacity of emulsion fracturing fluid, characterized in that, The apparent density ρ of the emulsion fracturing fluid is measured using a buoyancy-type densitometer; the actual density ρ0 of the emulsion fracturing fluid is measured using a gravimetric densitometer; the difference between the apparent density ρ and the actual density ρ0 of the emulsion fracturing fluid is used to represent the sand-carrying capacity of the emulsion fracturing fluid. The larger the difference, the greater the sand-carrying capacity of the emulsion fracturing fluid.

2. The method for determining the sand-carrying capacity of emulsion fracturing fluid as described in claim 1, characterized in that, The buoyancy-type density metering range is 0.8–1.5 g / cm³. 3 .

3. The method for determining the sand-carrying capacity of emulsion fracturing fluid as described in claim 1, characterized in that, The viscosity of the emulsion fracturing fluid is 132–192 mPa·s.

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