Method and apparatus for determining relative viscosity of sand-hydrate slurry

Abstract

The present invention provides a method and device for determining the relative viscosity of a sand-hydrate slurry. The corresponding method includes: determining the effective volume fraction of aggregates according to the actual volume fraction of aggregates of sand-hydrate, the particle size of aggregates, the initial particle size of aggregates, and the fractal dimension function of hydrates; determining the structure characteristic characterization parameters of aggregates and the interaction characterization parameters between particles according to the effective volume fraction; determining the relative viscosity of the sand-hydrate slurry according to the structure characteristic characterization parameters, the interaction characterization parameters, the optimal weighting factor of the pre-determined sand particle volume fraction or the optimal weighting factor of the hydrate volume fraction. The present invention quantifies the influence of sand particles on the viscosity of hydrate slurry by using a weighting factor, and combines the effective medium theory to establish a relative viscosity calculation method under constant volume fraction and variable shear rate conditions. This method can be widely applied to directions such as hydrate exploitation, hydrate risk control technology, and flow safety assurance.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and particularly relates to a method and device for determining the relative viscosity of a sand-hydrate slurry. Background Art

[0002] With the increasing depletion of onshore oil and gas resources, oil and gas exploration and development are gradually moving towards the deep sea. The special environment of low temperature and high pressure on the seabed provides favorable conditions for the formation of hydrates. However, during the oil and gas pipeline transportation process, the formation, blockage, and deposition of hydrates will damage equipment such as pipelines and valves, thus hindering the safe operation of pipelines and affecting the safe exploitation and transportation of natural gas. Among them, the viscosity characteristics of hydrate slurries are an important part of pipeline transportation engineering. Effective and accurate viscosity prediction is conducive to laying the foundation for the research of hydrate slurries and realizing the effective application of hydrate slurry transportation technology in engineering. Its research can provide basic data for hydrate risk control technology and the flow safety guarantee of deep-water oil and gas pipelines, which is of great significance.

[0003] During the pipeline transportation of slurries from the deep sea to an offshore platform, solid particles such as sand grains and hydrates exist in the system, thus presenting a multiphase flow pattern of the slurry, and the viscosity characteristics of the slurry become complex and unknown. During multiphase mixed transportation, the viscosity characteristics of the slurry can be used as an important index to judge its fluidity. It can effectively predict the blockage and deposition of hydrates, providing clear experimental data support and theoretical guidance for the prevention and control of hydrates in pipelines and risk control. Summary of the Invention

[0004] Aiming at the problems in the prior art, the sand-hydrate slurry relative viscosity determination method and device provided by the present invention use a weighting factor to quantify the influence of sand grains on the viscosity of hydrate slurries, and establish a relative viscosity calculation method under constant volume fraction and variable shear rate conditions in combination with the effective medium theory. This method can be widely applied to directions such as hydrate exploitation, hydrate risk control technology, and flow safety guarantee.

[0005] In a first aspect, the present invention provides a method for determining the relative viscosity of a sand-hydrate slurry, including:

[0006] Determining the effective volume fraction of the aggregate according to the actual volume fraction of the aggregate of sand-hydrate, the particle size of the aggregate, the initial particle size of the aggregate, and the fractal dimension function of the hydrate;

[0007] Determining the structural characteristic characterization parameter of the aggregate and the interaction characterization parameter between particles according to the effective volume fraction;

[0008] Determine the relative viscosity of the sand-hydrate slurry according to the structural characteristic characterization parameter, the interaction characterization parameter, the optimal weighting factor of the sand volume fraction or the optimal weighting factor of the hydrate volume fraction determined in advance.

[0009] In one embodiment, the method for determining the relative viscosity of the sand-hydrate slurry further includes:

[0010] Determine the relationship between the particle size of the aggregate and the particle size of the hydrate according to the shear stress for forming the aggregate.

[0011] In one embodiment, the determining the structural characteristic characterization parameter of the aggregate and the interaction characterization parameter between particles according to the effective volume fraction includes:

[0012] Determine the relationship between the effective volume fraction and the actual volume fraction according to the relationship between the particle size of the aggregate and the particle size of the hydrate and the fractal dimension function;

[0013] Determine the structural characteristic characterization parameter of the aggregate and the interaction characterization parameter between particles according to the relationship between the effective volume fraction and the actual volume fraction.

[0014] In one embodiment, the method for determining the optimal weighting factor of the sand volume fraction and the optimal weighting factor of the hydrate volume fraction includes the following steps:

[0015] Under laboratory conditions, measure the structural characteristic characterization parameters and interaction characterization parameters corresponding to the weighting factors of different sand volume fractions;

[0016] Determine the optimal weighting factor of the sand volume fraction and the optimal weighting factor of the hydrate volume fraction according to the structural characteristic characterization parameters and interaction characterization parameters corresponding to the weighting factors of different sand volume fractions.

[0017] In a second aspect, the present invention provides a device for determining the relative viscosity of a sand-hydrate slurry, and the device includes:

[0018] An effective volume fraction determination module, configured to determine the effective volume fraction of the aggregate according to the actual volume fraction of the aggregate of the sand-hydrate, the particle size of the aggregate, the initial particle size of the aggregate, and the fractal dimension function of the hydrate;

[0019] A characterization parameter determination module, configured to determine the structural characteristic characterization parameter of the aggregate and the interaction characterization parameter between particles according to the effective volume fraction;

[0020] A relative viscosity determination module, configured to determine the relative viscosity of the sand-hydrate slurry according to the structural characteristic characterization parameter, the interaction characterization parameter, a pre-determined optimal weighting factor of the sand volume fraction, or an optimal weighting factor of the hydrate volume fraction.

[0021] In one embodiment, the apparatus for determining the relative viscosity of the sand-hydrate slurry further includes:

[0022] A particle size relationship determination module, configured to determine the relationship between the particle size of the aggregate and the particle size of the hydrate according to the shear stress for forming the aggregate.

[0023] In one embodiment, the characterization parameter determination module includes:

[0024] A volume fraction determination unit, configured to determine the relationship between the effective volume fraction and the actual volume fraction according to the relationship between the particle size of the aggregate and the particle size of the hydrate and the fractal dimension function;

[0025] A characterization parameter determination unit, configured to determine the structural characteristic characterization parameter of the aggregate and the interaction characterization parameter between particles according to the relationship between the effective volume fraction and the actual volume fraction.

[0026] In one embodiment, the apparatus for determining the relative viscosity of the sand-hydrate slurry further includes: an optimal weighting factor determination module, configured to determine an optimal weighting factor of the sand volume fraction and an optimal weighting factor of the hydrate volume fraction, and the optimal weighting factor determination module includes:

[0027] A laboratory measurement unit, configured to measure the structural characteristic characterization parameter and the interaction characterization parameter corresponding to the weighting factors of different sand volume fractions under laboratory conditions;

[0028] An optimal weighting factor determination unit, configured to determine an optimal weighting factor of the sand volume fraction and the optimal weighting factor of the hydrate volume fraction according to the structural characteristic characterization parameter and the interaction characterization parameter corresponding to the weighting factors of different sand volume fractions.

[0029] In a third aspect, the present invention provides an electronic device, including a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the program, the steps of the method for determining the relative viscosity of the sand-hydrate slurry are implemented.

[0030] In a fourth aspect, the present invention provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method for determining the relative viscosity of the sand-hydrate slurry are implemented.

[0031] As can be seen from the above description, the method and device for determining the relative viscosity of a sand-hydrate slurry provided by the embodiments of the present invention, the corresponding method includes: First, determine the effective volume fraction of the aggregates according to the actual volume fraction of the aggregates of sand-hydrate, the particle size of the aggregates, the initial particle size of the aggregates, and the fractal dimension function of the hydrate; Then, determine the structure characteristic characterization parameters of the aggregates and the interaction characterization parameters between the particles according to the effective volume fraction; Finally, determine the relative viscosity of the sand-hydrate slurry according to the structure characteristic characterization parameters, the interaction characterization parameters, the optimal weighting factor of the sand grain volume fraction or the optimal weighting factor of the hydrate volume fraction determined in advance. The present invention can be used to calculate and predict the relative viscosity of a sand-hydrate slurry. It is widely used in the field of hydrate exploitation, can deepen the understanding of the flow law of hydrates in the sand particle dispersion system, and combined with the actual engineering, provide favorable basic data for the safe and stable transportation in actual oil and gas pipelines, and provide theoretical support for the operation safety of subsea production and development systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0033] Figure 1 Flow schematic diagram of the method for determining the relative viscosity of a sand-hydrate slurry in the embodiments of the present invention Figure 1 ;

[0034] Figure 2 Flow schematic diagram of the method for determining the relative viscosity of a sand-hydrate slurry in the embodiments of the present invention Figure 2 ;

[0035] Figure 3 Flow schematic diagram of step 200 in the embodiments of the present invention;

[0036] Figure 4 Flow schematic diagram of the method for determining the relative viscosity of a sand-hydrate slurry in the embodiments of the present invention Figure 3 ;

[0037] Figure 5 Flow schematic diagram of step 500 in the embodiments of the present invention;

[0038] Figure 6 Flow schematic diagram of the method for determining the relative viscosity of a sand-hydrate slurry in a specific application example of the present invention;

[0039] Figure 7Schematic diagram of the comparison between the calculated predicted value and the actual value of the relative viscosity in the specific application example of the present invention Figure 1 ;

[0040] Figure 8 Schematic diagram of the comparison between the calculated predicted value and the actual value of the relative viscosity in the specific application example of the present invention Figure 2 ;

[0041] Figure 9 Schematic diagram of the comparison between the calculated predicted value and the actual value of the relative viscosity in the specific application example of the present invention Figure 3 ;

[0042] Figure 10 Schematic diagram of the comparison between the calculated predicted value and the actual value of the relative viscosity in the specific application example of the present invention Figure 4 ;

[0043] Figure 11 Schematic diagram of the structure of the device for determining the relative viscosity of sand-hydrate slurry in the embodiment of the present invention Figure 1 ;

[0044] Figure 12 Schematic diagram of the structure of the device for determining the relative viscosity of sand-hydrate slurry in the embodiment of the present invention Figure 2 ;

[0045] Figure 13 Schematic diagram of the composition structure of the characterization parameter determination module 20 in the device for determining the relative viscosity of sand-hydrate slurry in the embodiment of the present invention;

[0046] Figure 14 Schematic diagram of the structure of the device for determining the relative viscosity of sand-hydrate slurry in the embodiment of the present invention Figure 3 ;

[0047] Figure 15 Schematic diagram of the composition structure of the optimal weighting factor determination module 50 in the device for determining the relative viscosity of sand-hydrate slurry in the embodiment of the present invention;

[0048] Figure 16 Schematic diagram of the structure of the electronic device in the embodiment of the present invention. Detailed implementation manners

[0049] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0050] It should be noted that, in the description, claims and above-mentioned drawings of this application, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that comprises a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0051] It should be noted that, without conflict, the embodiments in this application and the features in the embodiments can be combined with each other. The following will detail this application with reference to the drawings and in combination with the embodiments.

[0052] An embodiment of the present invention provides a specific implementation manner of a method for determining the relative viscosity of a sand-hydrate slurry. Refer to Figure 1 , and the method specifically includes the following contents:

[0053] Step 100: Determine the effective volume fraction of the aggregates according to the actual volume fraction of the aggregates of sand-hydrate, the particle size of the aggregates, the initial particle size of the aggregates, and the fractal dimension function of the hydrate.

[0054] The hydrate in Step 100 refers to white crystals formed by certain components in natural gas and water under certain temperature and pressure conditions, with an appearance similar to dense ice and snow, and a density of 0.88 - 0.90 g / cm 3 . The hydrate is a kind of clathrate crystal inclusion, where water molecules form a cage-shaped crystal through hydrogen bonding, and gas molecules are surrounded in the crystal lattice.

[0055] It should be noted that the aggregates mentioned in this application refer to the particle aggregates formed by sand grains and hydrates, and the slurry refers to the suspension formed by sand grains, hydrates and water.

[0056] Step 200: Determine the structure characteristic characterization parameter of the aggregates and the interaction characterization parameter between the particles according to the effective volume fraction.

[0057] It should be noted that the interaction characterization parameter can characterize the interaction characteristics between particles and is a parameter related to the aggregate fragmentation mechanism.

[0058] Step 300: Determine the relative viscosity of the sand-hydrate slurry according to the structure characteristic characterization parameter, the interaction characterization parameter, the optimal weighting factor of the sand grain volume fraction determined in advance, or the optimal weighting factor of the hydrate volume fraction.

[0059] In the aggregate sand-containing system, the particle volume fraction includes two parts: the hydrate volume fraction and the sand grain volume fraction. Since the proportion of the sand grain volume fraction is relatively small, the weighted coefficient method is used to correct the particle volume fraction. Specifically, laboratory data and calculation data are used for fitting to inversely deduce the optimal weighting factor, and then the relative viscosity of the sand-hydrate slurry is determined.

[0060] As can be seen from the above description, for the method for determining the relative viscosity of the sand-hydrate slurry provided by the embodiment of the present invention, first, the effective volume fraction of the aggregate is determined according to the actual volume fraction of the aggregate of the sand-hydrate, the particle size of the aggregate, the initial particle size of the aggregate, and the fractal dimension function of the hydrate; then, the structural characteristic characterization parameter of the aggregate and the interaction characterization parameter between the particles are determined according to the effective volume fraction; finally, the relative viscosity of the sand-hydrate slurry is determined according to the structural characteristic characterization parameter, the interaction characterization parameter, the optimal weighting factor of the sand grain volume fraction or the optimal weighting factor of the hydrate volume fraction determined in advance. The present invention can be used to study the viscosity characteristics of the sand-hydrate slurry in a multiphase system and predict the viscosity of the slurry, which has important practical significance for the process design of the development or exploitation of oil and gas and natural gas hydrate resources.

[0061] In one embodiment, referring to Figure 2 , the method for determining the relative viscosity of the sand-hydrate slurry further includes:

[0062] Step 400: Determine the relationship between the particle size of the aggregate and the particle size of the hydrate according to the shear stress for forming the aggregate.

[0063] According to the fractal theory, the ratio of the particle size of the hydrate aggregate to the particle size of the hydrate is related to the shear action and can be expressed by Equation (1):

[0064]

[0065] where τ is the shear stress that the aggregate can form, in Pa; τ0 is the critical shear stress that the aggregate can form, in Pa; the value of m c depends on the interaction characteristics between the particles and is a parameter related to the aggregate fragmentation mechanism, usually between 0.3 and 0.5.

[0066] In one embodiment, referring to Figure 3 , step 200 includes:

[0067] Step 201: Determine the relationship between the effective volume fraction and the actual volume fraction according to the relationship between the particle size of the aggregate and the particle size of the hydrate and the fractal dimension function;

[0068] According to the effective medium theory, the commonly used formula for calculating the viscosity of the suspension system is shown in Equation (2):

[0069]

[0070] Where η r is the relative apparent viscosity of the slurry; is the effective volume fraction; is the maximum volume fraction of hydrate.

[0071] Introduce the relationship between the effective volume fraction and the actual volume fraction in the Carmargo-Palermo model, and express the effective volume fraction as a function of the actual volume fraction in the system, the aggregate particle size d A , the initial particle size d p and the fractal dimension f of hydrate:

[0072]

[0073] Where d A is the aggregate particle size of hydrate, m; d p is the particle size of hydrate particles, m.

[0074] Step 202: Determine the structure characteristic characterization parameters of the aggregates and the interaction characterization parameters between particles according to the relationship between the effective volume fraction and the actual volume fraction.

[0075] Combining equations (1) and (3) gives equations (4) to (6):

[0076]

[0077] X = (3 - f)m c (5)

[0078]

[0079] Where X = (3 - f)m characterizes the aggregate structure characteristics; characterizes the interaction between particles, the aggregate structure characteristics and the fragmentation mechanism.

[0080] In one embodiment, referring to Figure 4 , the method for determining the relative viscosity of sand-hydrate slurry further includes:

[0081] Step 500: Determine the optimal weighting factor of the sand particle volume fraction and the optimal weighting factor of the hydrate volume fraction. Further, referring to Figure 5 , step 500 includes:

[0082] Step 501: Under laboratory conditions, measure the structure characteristic characterization parameters and interaction characterization parameters corresponding to the weighting factors of different sand particle volume fractions;

[0083] Step 502: Determine the optimal weighting factor of the sand volume fraction and the optimal weighting factor of the hydrate volume fraction according to the structure characteristic parameters and interaction characteristic parameters corresponding to the weighting factors of different sand volume fractions.

[0084] Specifically, in Steps 501 and 502, through conducting experiments, experimental data such as pressure, temperature, slurry viscosity, shear stress, etc. under different experimental conditions are obtained. Combining with relevant knowledge of phase equilibrium, the gas consumption is calculated according to the changes in temperature and pressure, and then the hydrate generation amount and the hydrate volume fraction in the liquid phase are obtained. Then, several experimental data points are selected to fit ln(1 - η r -0.4 ) and lnτ, and the weighting factor n is gradually taken from 0, and the values of parameters X and Z corresponding to different weighting factors n can be obtained. Substitute the X and Z values corresponding to different n values into the calculation of the relative viscosity of the slurry, compare the actual values and calculated values of the fitting data points, and the most suitable weighting factor n value and its corresponding X and Z values under different experimental conditions can be obtained by calculating the error.

[0085] To further illustrate the present solution, the present invention also provides a specific application example of the method for determining the relative viscosity of sand-hydrate slurry, and the specific application example specifically includes the following content. See Figure 6 .

[0086] S1: Determine the effective volume fraction of the aggregate according to the actual volume fraction of the sand-hydrate aggregate, the particle size of the aggregate, the initial particle size of the aggregate, and the fractal dimension function of the hydrate.

[0087] For the specific implementation process, see Formula (2) and Formula (3), which will not be repeated here.

[0088] S2: Determine the structure characteristic parameters of the aggregate and the interaction characteristic parameters between particles according to the effective volume fraction.

[0089] For the specific implementation process, see Formulas (1), (4) to (6).

[0090] S3: Determine the optimal weighting factor of the sand volume fraction.

[0091] First, build an experimental platform and obtain the experimental data of the hydrate viscosity of the sand-hydrate system with different initial pressures, shear rates, sand concentrations, and temperature experimental values: The non-equilibrium decomposition experiment of the sand-hydrate slurry is carried out in an Anton Paar rheometer, and the model of the rheometer is MCR 101. The inner cylinder radius and diameter used in the experiment are 13.33 mm and 40.01 mm respectively, and the inner diameter of the outer cylinder is 14.46 mm. The temperature control range of the rheometer is -20°C to 150°C.

[0092] Experimental procedures:

[0093] 1) Measure 20 ml of water, weigh 0.1 wt% of glass microspheres, add them to a beaker and stir with a glass rod. Then add the mixture containing micron-sized sand grains into the measuring cup of the rheometer.

[0094] 2) Measure another 10 ml of water, place it in the beaker and stir to dissolve the solid particles adhering to the beaker wall and bottom in the water. Then pour the solution into the measuring cup.

[0095] 3) Open the Rheoplus software to edit the rheometer test program, and set the experimental temperature, shear rate, and experimental time. The experimental process is set to stir the solution at a shear rate of 700 s -1 for 1 h, and then cool it down to 0.5 °C at a rate of 0.5 °C / min and maintain it until the experiment ends.

[0096] 4) Open the valve of the high-pressure gas cylinder, and then turn on the intake valve and the booster pump in sequence.

[0097] 5) Adjust the intake valve and the pressure relief valve to ensure that the initial pressure is 8.8 MPa.

[0098] 6) Close all valves, start the rheometer test program, and the program automatically records the pressure, temperature, and viscosity data during the hydrate formation process.

[0099] 7) If the pressure change does not exceed 0.1 MPa within 30 min and the curve viscosity is basically stable, it is regarded as the stable state of hydrate formation, and start the software program for the subsequent non-equilibrium decomposition experiment.

[0100] 8) The experimental process is set to stir the solution at a shear rate of 700 s -1 and a temperature of 0.5 °C for 40 min.

[0101] 9) At a temperature of 0.5 °C, linearly increase the shear rate from 100 to 800 s within 700 s -1 and measure the viscosity change of the slurry.

[0102] 10) Increase the temperature by 2 °C at a heating rate of 0.5 °C / min. During this process, maintain the shear rate at 700 s -1 .

[0103] 11) After heating to 2.5 °C, maintain the shear rate at 700 s within 5 min -1 .

[0104] 12) Continuously increase the temperature to 2.5, 4.5, 6.5, 8.5, 10.5, 12.5 °C, and repeat steps 9) - 11) for the shear rate change process to measure the change of slurry viscosity with shear rate at different temperature steps.

[0105] 13) After the experiment, evacuate the gas, clean the experimental instruments, and wash the beakers.

[0106] By conducting experiments, experimental data such as pressure, temperature, slurry viscosity, and shear stress under different experimental conditions are obtained. Combining with the relevant knowledge of phase equilibrium, the gas consumption is calculated according to the temperature and pressure changes, and then the hydrate formation amount and the volume fraction of hydrate in the liquid phase are obtained. Subsequently, several experimental data points are selected to fit ln(1 - η r -0.4 ) and lnτ, and the weighted factor n is gradually taken from 0, and the values of parameters X and Z corresponding to different weighted factors n can be obtained. Substitute the X and Z values corresponding to different n values into the calculation of the relative viscosity of the slurry, compare the actual values and calculated values of the fitting data points, and the most suitable weighted factor n value and its corresponding X and Z values under different experimental conditions can be obtained by calculating the error.

[0107] S4: Determine the relative viscosity of the sand-hydrate slurry according to the structure characteristic characterization parameter, the interaction characterization parameter, the optimal weighted factor of the pre-determined sand volume fraction or the optimal weighted factor of the hydrate volume fraction.

[0108] Specifically, substitute formulas (1), (3) to (6) into formula (2) to obtain formula (7):

[0109]

[0110] Take the logarithm of formula (7) and further transform it to obtain calculation formula (8). By fitting ln(1 - η r -0.4 ) and lnτ, the values of parameters X and Z can be obtained. The following formula shows that at a certain solid volume fraction, ln(1 - η r -0.4 ) and lnτ are linearly related, and the slope of the curve is -X (X > 0).

[0111]

[0112] In the sand-containing system, the particle volume fraction includes two parts: the hydrate volume fraction and the sand particle volume fraction. Since the sand particle volume fraction accounts for a relatively small proportion, the weighted coefficient method is used to correct the particle volume fraction. Based on the above inferences, the actual volume fraction in the system can be obtained as shown in formula (9):

[0113]

[0114] In the formula, is the hydrate volume fraction; is the volume fraction of sand grains; n is the weighting factor, which characterizes the influence degree of the sand grain volume fraction on the particle volume fraction, and takes values sequentially starting from 0.

[0115] Combining equations (1)-(9), the following two equations are the calculation methods for the relative viscosity of the sand-hydrate slurry with the coupled weighting factor:

[0116]

[0117] Among them, η r is the relative apparent viscosity of the slurry; X is the fitting parameter, which characterizes the aggregate structure characteristics; Z is the fitting parameter, which characterizes the interaction between particles, the aggregate structure characteristics and the fragmentation mechanism; τ is the shear stress, Pa; is the hydrate volume fraction; is the maximum hydrate volume fraction; c is the mass fraction of sand grains in the total solution; ρ s characterizes the sand grain density and is taken according to the material physical properties; ρ w is the density of water, 1.0 g / cm 3 ; n is the weighting factor, which characterizes the influence degree of the sand grain volume fraction on the particle volume fraction, and takes values sequentially starting from 0;

[0118] After determining the values of n, X, and Z under different experimental conditions, other data points under the same experimental conditions can be selected, and equation (10) can be substituted to calculate the relative viscosity of the sand-hydrate coupled system slurry under different sand concentrations.

[0119] S5: Error checking.

[0120] See Figures 7 to 10 , calculate the viscosity of the stabilized slurry under different sand concentrations. In the systems with sand concentrations of 0 wt%, 0.1 wt%, 0.5 wt%, and 1.5 wt%, five data points under different experimental conditions are selected and substituted into the relative viscosity model for calculation. By comparing and analyzing the experimental values with the model calculation values, it can be seen that the model calculation values are in good agreement with the experimental values, and the maximum error is 12.7%. It can be seen that the method for determining the relative viscosity of the sand-hydrate slurry provided by this application can accurately predict the relative viscosity of the hydrate slurry under different experimental conditions.

[0121] As can be seen from the above description, the method for determining the relative viscosity of a sand-hydrate slurry provided by the embodiments of the present invention includes the following steps: First, determine the effective volume fraction of the aggregates according to the actual volume fraction of the aggregates of sand-hydrate, the particle size of the aggregates, the initial particle size of the aggregates, and the fractal dimension function of the hydrate; then, determine the structure characteristic characterization parameters of the aggregates and the interaction characterization parameters between the particles according to the effective volume fraction; finally, determine the relative viscosity of the sand-hydrate slurry according to the structure characteristic characterization parameters, the interaction characterization parameters, the optimal weighting factor of the sand grain volume fraction or the optimal weighting factor of the hydrate volume fraction determined in advance. The present invention can be used to calculate and predict the relative viscosity of a sand-hydrate slurry, and is widely applied in the field of hydrate exploitation, which can deepen the understanding of the flow law of hydrates in a sand grain dispersion system, and combined with engineering practice, provide favorable basic data for the safe and stable transportation in actual oil and gas pipelines, and provide theoretical support for the operation safety of subsea production and development systems.

[0122] Based on the same inventive concept, the embodiments of the present application also provide a device for determining the relative viscosity of a sand-hydrate slurry, which can be used to implement the method described in the above embodiments, as described in the following embodiments. Since the principle of solving problems by the device for determining the relative viscosity of a sand-hydrate slurry is similar to that of the method for determining the relative viscosity of a sand-hydrate slurry, the implementation of the device for determining the relative viscosity of a sand-hydrate slurry can refer to the implementation of the method for determining the relative viscosity of a sand-hydrate slurry, and the repeated parts will not be described again. As used hereinafter, the term "unit" or "module" can be a combination of software and / or hardware that can achieve a predetermined function. Although the systems described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0123] The embodiments of the present invention provide a specific implementation manner of a device for determining the relative viscosity of a sand-hydrate slurry that can implement the method for determining the relative viscosity of a sand-hydrate slurry. Refer to Figure 11 , the device for determining the relative viscosity of a sand-hydrate slurry specifically includes the following contents:

[0124] An effective volume fraction determination module 10, configured to determine the effective volume fraction of the aggregates according to the actual volume fraction of the aggregates of sand-hydrate, the particle size of the aggregates, the initial particle size of the aggregates, and the fractal dimension function of the hydrate;

[0125] A characterization parameter determination module 20, configured to determine the structure characteristic characterization parameters of the aggregates and the interaction characterization parameters between the particles according to the effective volume fraction;

[0126] The relative viscosity determination module 30 is configured to determine the relative viscosity of the sand-hydrate slurry according to the structural feature characterization parameter, the interaction characterization parameter, the optimal weighting factor of the sand volume fraction determined in advance, or the optimal weighting factor of the hydrate volume fraction.

[0127] In one embodiment, referring to Figure 12 , the sand-hydrate slurry relative viscosity determination device further includes:

[0128] The particle size relationship determination module 40 is configured to determine the relationship between the particle size of the aggregate and the particle size of the hydrate according to the shear stress for forming the aggregate.

[0129] In one embodiment, referring to Figure 13 , the characterization parameter determination module 20 includes:

[0130] The volume fraction determination unit 201 is configured to determine the relationship between the effective volume fraction and the actual volume fraction according to the relationship between the particle size of the aggregate and the particle size of the hydrate and the fractal dimension function;

[0131] The characterization parameter determination unit 202 is configured to determine the structural feature characterization parameter of the aggregate and the interaction characterization parameter between the particles according to the relationship between the effective volume fraction and the actual volume fraction.

[0132] In one embodiment, referring to Figure 14 , the sand-hydrate slurry relative viscosity determination device further includes: an optimal weighting factor determination module 50, configured to determine the optimal weighting factor of the sand volume fraction and the optimal weighting factor of the hydrate volume fraction,

[0133] In one embodiment, referring to Figure 15 , the optimal weighting factor determination module 50 includes:

[0134] The laboratory measurement unit 501 is configured to measure the structural feature characterization parameter and the interaction characterization parameter corresponding to the weighting factor of different sand volume fractions under laboratory conditions;

[0135] The optimal weighting factor determination unit 502 is configured to determine the optimal weighting factor of the sand volume fraction and the optimal weighting factor of the hydrate volume fraction according to the structural feature characterization parameter and the interaction characterization parameter corresponding to the weighting factor of different sand volume fractions.

[0136] As can be seen from the above description, the apparatus for determining the relative viscosity of a sand-hydrate slurry provided by the embodiments of the present invention includes: first, determining the effective volume fraction of the aggregates according to the actual volume fraction of the aggregates of sand-hydrate, the particle size of the aggregates, the initial particle size of the aggregates, and the fractal dimension function of the hydrate; then, determining the structure characteristic characterization parameters of the aggregates and the interaction characterization parameters between the particles according to the effective volume fraction; finally, determining the relative viscosity of the sand-hydrate slurry according to the structure characteristic characterization parameters, the interaction characterization parameters, the optimal weighting factor of the sand grain volume fraction or the optimal weighting factor of the hydrate volume fraction determined in advance. The present invention can be used to calculate and predict the relative viscosity of a sand-hydrate slurry. It is widely applied in the field of hydrate exploitation, can deepen the understanding of the flow law of hydrates in a sand grain dispersion system, and combined with engineering practice, provides favorable basic data for the safe and stable transportation in actual oil and gas pipelines, and provides theoretical support for the operation safety of subsea production and development systems.

[0137] The embodiments of the present application also provide a specific implementation manner of an electronic device that can implement all the steps in the method for determining the relative viscosity of a sand-hydrate slurry in the above embodiments. Refer to Figure 16 , and the electronic device specifically includes the following contents:

[0138] A processor 1201, a memory 1202, a communication interface 1203, and a bus 1204;

[0139] Among them, the processor 1201, the memory 1202, and the communication interface 1203 communicate with each other through the bus 1204; the communication interface 1203 is used to implement information transmission between related devices such as a server-side device, a measurement device, and a user-side device.

[0140] The processor 1201 is used to call the computer program in the memory 1202. When the processor executes the computer program, it implements all the steps in the method for determining the relative viscosity of a sand-hydrate slurry in the above embodiments. For example, when the processor executes the computer program, it implements the following steps:

[0141] Step 100: Determine the effective volume fraction of the aggregates according to the actual volume fraction of the aggregates of sand-hydrate, the particle size of the aggregates, the initial particle size of the aggregates, and the fractal dimension function of the hydrate;

[0142] Step 200: Determine the structure characteristic characterization parameters of the aggregates and the interaction characterization parameters between the particles according to the effective volume fraction;

[0143] Step 300: Determine the relative viscosity of the sand-hydrate slurry according to the structural characteristic characterization parameter, the interaction characterization parameter, the optimal weighting factor of the sand volume fraction determined in advance, or the optimal weighting factor of the hydrate volume fraction.

[0144] An embodiment of the present application further provides a computer-readable storage medium capable of implementing all steps in the method for determining the relative viscosity of the sand-hydrate slurry in the above embodiment. A computer program is stored on the computer-readable storage medium. When the computer program is executed by a processor, all steps in the method for determining the relative viscosity of the sand-hydrate slurry in the above embodiment are implemented. For example, when the processor executes the computer program, the following steps are implemented:

[0145] Step 100: Determine the effective volume fraction of the aggregate according to the actual volume fraction of the aggregate of the sand-hydrate, the particle size of the aggregate, the initial particle size of the aggregate, and the fractal dimension function of the hydrate.

[0146] Step 200: Determine the structural characteristic characterization parameter of the aggregate and the interaction characterization parameter between particles according to the effective volume fraction.

[0147] Step 300: Determine the relative viscosity of the sand-hydrate slurry according to the structural characteristic characterization parameter, the interaction characterization parameter, the optimal weighting factor of the sand volume fraction determined in advance, or the optimal weighting factor of the hydrate volume fraction.

[0148] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the hardware + program type embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiments.

[0149] The above describes specific embodiments of this specification. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims can be executed in a different order than in the embodiments and still achieve the desired result. Additionally, the processes depicted in the figures do not necessarily require the specific order or sequential order shown to achieve the desired result. In certain implementations, multitasking and parallel processing are also possible or may be advantageous.

[0150] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0151] Although the embodiments of this specification provide method operation steps as described in the embodiments or flowcharts, more or fewer operation steps may be included based on conventional or non-creative means. The order of steps listed in the embodiments is only one way among many execution orders of the steps and does not represent the only execution order. When the actual device or terminal product is executed, it can be executed in the order of the method shown in the embodiments or the drawings or executed in parallel (for example, in a parallel processor or multi-threaded processing environment, or even in a distributed data processing environment). The term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, product or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, product or device. Without further limitation, there is no exclusion of the presence of additional identical or equivalent elements in the process, method, product or device comprising the said elements.

[0152] Specific embodiments of the present invention are used to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only for helping to understand the method and its core idea of the present invention; at the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A method for determining the relative viscosity of a sand-hydrate slurry, characterized in that, Including: Determining the effective volume fraction of the aggregates according to the actual volume fraction of the sand-hydrate aggregates, the particle size of the aggregates, the initial particle size of the aggregates, and the fractal dimension function of the hydrate; Determining the structural characteristic characterization parameters of the aggregates and the interaction characterization parameters between the particles according to the effective volume fraction; Determining the relative viscosity of the sand-hydrate slurry according to the structural characteristic characterization parameters, the interaction characterization parameters, the optimal weighting factor of the sand particle volume fraction or the optimal weighting factor of the hydrate volume fraction determined in advance; The determining the structural characteristic characterization parameters of the aggregates and the interaction characterization parameters between the particles according to the effective volume fraction includes: Determining the relationship between the effective volume fraction and the actual volume fraction according to the relationship between the particle size of the aggregates and the particle size of the hydrate and the fractal dimension function; Determining the structural characteristic characterization parameters of the aggregates and the interaction characterization parameters between the particles according to the relationship between the effective volume fraction and the actual volume fraction; The method for determining the optimal weighting factor of the sand particle volume fraction and the optimal weighting factor of the hydrate volume fraction includes the following steps: Under laboratory conditions, measuring the structural characteristic characterization parameters and the interaction characterization parameters corresponding to the weighting factors of different sand particle volume fractions; Determining the optimal weighting factor of the sand particle volume fraction and the optimal weighting factor of the hydrate volume fraction according to the structural characteristic characterization parameters and the interaction characterization parameters corresponding to the weighting factors of different sand particle volume fractions; The determining the relative viscosity of the sand-hydrate slurry according to the structural characteristic characterization parameters, the interaction characterization parameters, the optimal weighting factor of the sand particle volume fraction or the optimal weighting factor of the hydrate volume fraction determined in advance includes: In the aggregate-containing sand system, the particle volume fraction includes two parts: the hydrate volume fraction and the sand particle volume fraction, and the proportion of the sand particle volume fraction is relatively small. Therefore, the weighted coefficient method is used to correct the particle volume fraction. Specifically, the laboratory data and the calculated data are fitted to inversely deduce the optimal weighting factor, and then the relative viscosity of the sand-hydrate slurry is determined.

2. The method for determining the relative viscosity of a sand-hydrate slurry according to claim 1, characterized in that, Also including: Determining the relationship between the particle size of the aggregates and the particle size of the hydrate according to the shear stress for forming the aggregates.

3. A device for determining the relative viscosity of a sand-hydrate slurry, characterized in that, Including: An effective volume fraction determination module for determining the effective volume fraction of the aggregates according to the actual volume fraction of the sand-hydrate aggregates, the particle size of the aggregates, the initial particle size of the aggregates, and the fractal dimension function of the hydrate; A characterization parameter determination module for determining the structural characteristic characterization parameters of the aggregates and the interaction characterization parameters between the particles according to the effective volume fraction; A relative viscosity determination module for determining the relative viscosity of the sand-hydrate slurry according to the structural characteristic characterization parameters, the interaction characterization parameters, the optimal weighting factor of the sand particle volume fraction or the optimal weighting factor of the hydrate volume fraction determined in advance; The characterization parameter determination module includes: A volume fraction determination unit for determining the relationship between the effective volume fraction and the actual volume fraction according to the relationship between the particle size of the aggregate and the particle size of the hydrate and the fractal dimension function; A characterization parameter determination unit for determining the structural characteristic characterization parameters of the aggregate and the interaction characterization parameters between particles according to the relationship between the effective volume fraction and the actual volume fraction; A device for determining the relative viscosity of a sand-hydrate slurry further includes: an optimal weighting factor determination module for determining the optimal weighting factor of the sand particle volume fraction and the optimal weighting factor of the hydrate volume fraction, and the optimal weighting factor determination module includes: A laboratory measurement unit for measuring the structural characteristic characterization parameters and the interaction characterization parameters corresponding to the weighting factors of different sand particle volume fractions under laboratory conditions; An optimal weighting factor determination unit for determining the optimal weighting factor of the sand particle volume fraction and the optimal weighting factor of the hydrate volume fraction according to the structural characteristic characterization parameters and the interaction characterization parameters corresponding to the weighting factors of different sand particle volume fractions; The determination of the relative viscosity of the sand-hydrate slurry according to the structural characteristic characterization parameters, the interaction characterization parameters, the pre-determined optimal weighting factor of the sand particle volume fraction or the optimal weighting factor of the hydrate volume fraction includes: In the aggregate-containing sand system, the particle volume fraction includes two parts, the hydrate volume fraction and the sand particle volume fraction, and the proportion of the sand particle volume fraction is relatively small. Therefore, the weighted coefficient method is used to correct the particle volume fraction. Specifically, laboratory data and calculation data are used for fitting to inversely deduce the optimal weighting factor, and then the relative viscosity of the sand-hydrate slurry is determined.

4. The device for determining the relative viscosity of a sand-hydrate slurry according to claim 3, characterized in that, It further includes: A particle size relationship determination module for determining the relationship between the particle size of the aggregate and the particle size of the hydrate according to the shear stress for forming the aggregate.

5. An electronic device, comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the steps of the method for determining the relative viscosity of the sand-hydrate slurry according to any one of claims 1 to 2.

6. A computer-readable storage medium, on which a computer program is stored, characterized in that, When the computer program is executed by the processor, it implements the steps of the method for determining the relative viscosity of the sand-hydrate slurry according to any one of claims 1 to 2.

Images