Dynamic scaling simulation experiment device and experiment analysis method

Abstract

The invention provides a dynamic scaling simulation experiment device and an experiment analysis method. The scaling condition in a pipe wall under the condition that fluid flows in a pipeline and the anti-scaling effect of a chemical anti-scaling agent can be simulated; compared with a static evaluation method used in the SY / T 5673 oilfield scale inhibitor performance evaluation method in the petroleum and natural gas industry standard, the device disclosed by the invention is adopted to evaluate the performance of the scale inhibitor, and is closer to the actual production; compared with a small field test, manpower, material resources, time and cost can be greatly saved.

Description

Technical Field

[0001] The present invention belongs to the field of application of oilfield scale inhibitors, and particularly relates to a dynamic scale formation simulation experimental device and an experimental analysis method. Background Art

[0002] During the water injection / hot water injection development process in the Bohai Oilfield, due to the presence of a certain amount of scaling ions such as Ca 2+ , Mg 2+ , HCO3 - in the injected water, scaling phenomena often occur in the process as the injection temperature changes. Therefore, in the oilfield development process, a scale prevention system needs to be added to the surface process and pipelines to delay the scaling phenomenon.

[0003] The scale prevention mechanisms of scale inhibitors include complexation solubilization, lattice distortion, electrostatic repulsion, and dispersion. According to these mechanisms, the macroscopic manifestations of scale prevention are divided into two aspects. One is that the scale inhibitor increases the solubility of inorganic scale, keeping more inorganic salts in a dissolved state; the other is that even if tiny crystals of scale are formed, the scale inhibitor prevents the aggregation or dense deposition of the crystals, making the scale not easily adhere to the inner wall of the pipe.

[0004] For the actual situation on site, whether the scale inhibitor increases the solubility of inorganic salts or prevents the growth and orderly aggregation of scale crystals, it can prevent the formation of a hard and dense scale layer on the inner wall of the heat exchanger.

[0005] Currently, the evaluation of scale inhibitors often adopts the "Petroleum and Natural Gas Industry Standard SY / T 5673 Performance Evaluation Method for Scale Inhibitors Used in Oilfields", which is a static evaluation method. The scaling system is kept at a constant temperature for 24 hours at a set temperature, and the scaling amount is evaluated by titrating and analyzing the change of scaling cations in the solution before and after the scaling reaction, and then the quality of the scale inhibitor is evaluated. This static evaluation method is carried out under the condition that the scaling system is completely static. However, from the on-site working conditions, the injected water flows in the pipeline, and the flow state and flow velocity will inevitably affect the deposition degree of scale on the inner wall of the coil. The indoor static experimental conditions are very different from the actual on-site working conditions, and it is impossible to evaluate the scaling deposition situation under the flowing condition of the fluid. Therefore, the static scale prevention experimental method is one-sided.

[0006] Through small-scale on-site tests, the actual situation on site can be more comprehensively reflected, and accurate evaluation and optimization results that conform to the actual situation on site can be obtained, such as key parameters such as scale inhibitor type, usage concentration, scaling rate, and pressure difference between the inlet and outlet of the heat exchanger. However, it has high costs, a long cycle, and requires a large amount of manpower and material resources. Therefore, it is necessary to find a more efficient and low-cost research method. Summary of the Invention

[0007] The present invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a dynamic scale formation simulation experimental device and an experimental analysis method.

[0008] The present invention is realized through the following technical solutions:

[0009] A dynamic scale formation simulation experimental device includes a water storage tank, a metering pump, a scale formation pipe, and a riser pipe that are sequentially connected through a connecting pipeline to form a circulation loop; the scale formation pipe is placed in an electrothermal constant temperature box.

[0010] In the above technical solution, the scale formation pipe is communicated with the inlet on the side wall of the riser pipe, and the outlet at the top of the riser pipe is communicated with the inlet of the water storage tank.

[0011] In the above technical solution, the bottom of the riser pipe is communicated with a transparent conical pipe, and the transparent conical pipe gradually reduces in diameter from top to bottom.

[0012] In the above technical solution, a 400-mesh filter screen is arranged at the outlet of the water storage tank; a 400-mesh filter screen is arranged at the upper outlet of the riser pipe.

[0013] In the above technical solution, the riser pipe is vertically placed.

[0014] A dynamic scale formation simulation experimental analysis method is characterized in that it includes:

[0015] (Ⅰ) Evaluating the influence of different factors on scale formation;

[0016] (Ⅱ) Quantitatively analyzing suspended scale and deposited scale;

[0017] (Ⅲ) Evaluating the scale prevention performance of chemical scale inhibitors.

[0018] In the above technical solution, the step (Ⅰ) of evaluating the influence of different factors on scale formation specifically includes:

[0019] (ⅰ) Fixing the fluid composition and the heating temperature of the scale formation pipe, changing the flow rate of the fluid, measuring the scale formation conditions at different flow rates, and then evaluating the influence of the flow rate of the fluid and the flow state of the fluid on the scale formation conditions;

[0020] (ⅱ) Fixing the fluid composition and the flow rate of the fluid, changing the heating temperature of the scale formation pipe, measuring the scale formation conditions at different heating temperatures of the scale formation pipe, and evaluating the influence of the heating temperature of the scale formation pipe on the scale formation conditions;

[0021] (ⅲ) Fixing the flow rate of the fluid and the heating temperature of the scale formation pipe, changing the fluid composition, measuring the scale formation conditions at different fluid compositions, and evaluating the influence of the fluid composition on the scale formation conditions.

[0022] In the above technical solution, the flow state of the fluid is determined by calculating the Reynolds number during fluid flow. The calculation formula for the Reynolds number is Re = dvρ / μ;

[0023] In the formula: Re is the Reynolds number, dimensionless; d is the diameter of the fouled pipe, in m; ρ is the fluid density, in kg / m 3 ; v is the flow velocity, in m / s; μ is the fluid viscosity, in Pa·s;

[0024] When the Reynolds number Re < 2300, the flow state of the fluid is laminar flow;

[0025] When 2300 < Re < 4000, the flow state of the fluid is in the transition state;

[0026] When the Reynolds number Re > 4000, the flow state of the fluid is turbulent flow.

[0027] In the above technical solution, the (II) quantitative analysis of suspended scale and deposited scale specifically includes:

[0028] (i) Using the titration analysis method, measure the concentrations of scaling cations at the outlet end and the inlet end of the storage tank respectively. The sampling time interval for the samples at the outlet end and the inlet end of the storage tank is determined according to the specific experimental situation;

[0029] (ii) According to the difference in the concentrations of scaling cations at the outlet end and the inlet end of the storage tank, use the equivalent law to calculate the total scaling amount of the system during the above sampling time interval;

[0030] (iii) Determine the amount of suspended scale according to the amount of scale separated in the riser pipe during the above sampling time interval;

[0031] (iv) Determine the amount of deposited scale in the fouled pipe during the sampling time interval according to the difference between the total scaling amount and the amount of floating scale.

[0032] In the above technical solution, the step (III) of evaluating the scale inhibition performance of the chemical scale inhibitor specifically includes:

[0033] (i) Measure the amount of deposited scale under the blank condition without adding the scale inhibitor;

[0034] (ii) Under the same test conditions as in step (i), measure the amount of deposited scale after adding different types of scale inhibitors;

[0035] (iii) Calculate the scale inhibition rate according to the reduction in the amount of deposited scale in step (ii) with the scale inhibitor and step (i) without the scale inhibitor, and evaluate the scale inhibition performance of different scale inhibitors;

[0036] (iv) Under the same test conditions as in step (i), measure the amount of deposited scale after adding different concentrations of the same scale inhibitor;

[0037] (ⅴ) Calculate the scale inhibition rates of scale inhibitors at different concentrations and determine the usage concentration of the scale inhibitor.

[0038] The beneficial effects of the present invention are as follows:

[0039] The present invention provides a dynamic scale formation simulation experimental device and an experimental analysis method, which can simulate the scale formation situation inside the pipe wall and the scale inhibition effect of chemical scale inhibitors under the condition of fluid flowing in the pipeline; using the device of the present invention to evaluate the performance of scale inhibitors is closer to the actual production than the static evaluation method used in the petroleum and natural gas industry standard "SY / T 5673 Evaluation Method for the Performance of Scale Inhibitors for Oil Fields"; compared with small-scale on-site tests, it can greatly save manpower, material resources, time and costs. Description of the Drawings

[0040] Figure 1 It is a schematic structural diagram of the dynamic scale formation simulation experimental device of the present invention.

[0041] Wherein:

[0042] 1, water storage tank; 2, metering pump; 3, scaling pipe; 4, electrothermal constant temperature box; 5, riser pipe; 6, transparent conical pipe.

[0043] For those of ordinary skill in the art, without creative efforts, other relevant drawings can be obtained based on the above drawings. Detailed Embodiments

[0044] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be further described below in conjunction with the drawings of the specification and through specific embodiments.

[0045] Embodiment 1

[0046] As Figure 1 shown, a dynamic scale formation simulation experimental device includes a water storage tank 1, a metering pump 2, a scaling pipe 3 and a riser pipe 5 that are sequentially connected through connecting pipelines to form a circulation loop; the scaling pipe 3 is communicated with the inlet on the side wall of the riser pipe 5, and the outlet at the top of the riser pipe 5 is communicated with the inlet of the water storage tank 1; the scaling pipe 3 is placed in the electrothermal constant temperature box 4.

[0047] The bottom of the riser pipe 5 is communicated with a transparent conical pipe 6, and the transparent conical pipe 6 gradually tapers from top to bottom.

[0048] The experimental fluid starts from the liquid storage tank 1, passes through the metering pump 2, the scaling pipe 3, the riser pipe 5 and returns to the liquid storage tank 1 to form a closed circulation.

[0049] The water storage tank 1 is used to store the fluid medium, and a 400-mesh filter screen is arranged at the outlet of the water storage tank 1 to prevent suspended solid particles in the liquid storage tank from entering the metering pump and the circulation loop;

[0050] The water storage tank 1 is made of plastic material, which has good chemical stability for the experimental fluid; the water storage tank is covered to prevent dust in the air from polluting the experimental medium.

[0051] The metering pump 2 provides power for the fluid circulation. A micro metering pump on the market can be selected, and the flow rate can be adjusted according to needs.

[0052] The scaling tube 3 is the place where the fluid undergoes scaling reaction. The fluid is heated in the scaling tube, and the scaling ions dissolved in the fluid precipitate from the solution after scaling. Part of the scale particles deposit on the inner wall of the scaling tube, and part of the scale particles are suspended in the fluid.

[0053] The electrothermal constant temperature oven 4 provides heat source for the scaling tube 3. It is a conventional commercially available device, and the heating temperature can be adjusted according to needs.

[0054] The riser tube 5 is a suspended scale separation component. The riser tube 5 is vertically placed. After the fluid enters the riser tube, the flow direction changes and the flow velocity decreases. The suspended scale carried by the fluid precipitates and is separated from the fluid; a 400-mesh filter screen is arranged at the upper outlet of the riser tube 5 to further capture the suspended scale that has not been completely deposited.

[0055] The transparent conical tube 6 is a component for observing the suspended scale. The transparent conical tube 6 is connected to the lower part of the riser tube 5. The suspended scale separated from the fluid in the riser tube 5 deposits in the transparent conical tube 6. Through the transparent conical tube 6, the color, morphology, and deposition amount of the suspended scale after precipitation can be visually observed.

[0056] Example 2

[0057] A dynamic scaling simulation experiment analysis method includes:

[0058] (Ⅰ) Evaluating the influence of different factors on scaling

[0059] The different factors include the flow velocity of the fluid, the flow pattern of the fluid, the heating temperature of the scaling tube, and the fluid composition;

[0060] (ⅰ) Fixing the fluid composition and the heating temperature of the scaling tube, changing the flow velocity of the fluid, measuring the scaling conditions at different flow velocities, and then evaluating the influence of the flow velocity and flow state of the fluid on the scaling conditions;

[0061] The flow condition is determined by calculating the Reynolds number when the fluid flows, and is divided into laminar flow, transitional state, and turbulent flow;

[0062] The flow state of the fluid is determined by calculating the Reynolds number when the fluid flows. The calculation formula of the Reynolds number is Re = dvρ / μ;

[0063] Where: Re is the Reynolds number, dimensionless; d is the diameter of the fouled tube, in m; ρ is the fluid density, in kg / m 3 ; v is the flow velocity, in m / s; μ is the fluid viscosity, in Pa·s;

[0064] When the Reynolds number Re < 2300, the flow state of the fluid is laminar flow;

[0065] When the Reynolds number 2300 < Re < 4000, the flow state of the fluid is transitional state;

[0066] When the Reynolds number Re > 4000, the flow state of the fluid is turbulent flow;

[0067] (ii) Fix the composition of the fluid and the flow velocity of the fluid, change the heating temperature of the fouled tube, measure the fouling conditions at different heating temperatures of the fouled tube, and evaluate the influence of the heating temperature of the fouled tube on the fouling conditions;

[0068] (iii) Fix the flow velocity of the fluid and the heating temperature of the fouled tube, change the fluid composition, measure the fouling conditions under different fluid compositions, and evaluate the influence of the fluid composition on the fouling conditions;

[0069] (II) Quantitative analysis of suspended scale and deposited scale

[0070] (i) Using the titration analysis method, measure the concentrations of scaling cations at the outlet end and the inlet end of the liquid storage tank respectively. The sampling time interval for the two samples is determined according to the specific experimental situation;

[0071] The titration analysis method uses an EDTA standard solution to perform complexometric titration on the fluid, so as to measure the concentration of scaling cations in the fluid at the outlet end of the liquid storage tank; Sampling at the outlet end of the liquid storage tank is a sample before fluid fouling. After a certain period of time, sampling is carried out at the inlet end of the liquid storage tank. Sampling at the inlet end of the liquid storage tank is a sample after fluid fouling. Using the same method. The concentration of scaling cations in the fouled fluid is measured by complexometric titration.

[0072] (ii) According to the difference in the concentrations of scaling cations at the outlet end and the inlet end of the liquid storage tank, use the equivalent law to calculate the total fouling amount of the system during the above time interval;

[0073] The total fouling amount is calculated based on the difference in the concentrations of scaling cations at the outlet end and the inlet end of the liquid storage tank. The calculation formula is S 总 =(C EDTA V 出 -C EDTA V 进 )M 垢 V / V 样

[0074] Where: S 总is the total amount of scale formed during the time interval between two samplings, in grams; C EDTA is the molar concentration of EDTA, in mol / L; V 出 is the volume of EDTA consumed by the sample at the outlet end of the liquid storage tank, in ml; V 进 is the volume of EDTA consumed by the sample at the inlet end of the liquid storage tank, in ml; M 垢 is the molar mass of the scale, in g / mol; V is the total volume of the fluid in the system, in L; V 样 is the volume of the titrand, in ml;

[0075] (iii) Determine the suspended scale amount based on the scale amount separated from the riser during the same time period. The two are equal;

[0076] The suspended scale can be obtained from the transparent conical tube at the lower part of the riser and placed in a clean weighing dish that has been weighed to a constant weight. It is dried in an oven at 105°C until a constant weight is achieved. The difference from the weighing dish is the suspended scale amount, denoted as S 悬 ;

[0077] The deposited scale amount S on the inner wall of the scaling tube = S 总- S 悬

[0078] (iv) Based on the difference between the total scale amount and the floating scale amount, the deposited scale amount in the scaling tube during the time interval between two samplings can be determined;

[0079] (III) Evaluate the scale inhibition performance of the chemical scale inhibitor

[0080] (i) Determine the deposited scale amount S0 under blank conditions without adding the scale inhibitor;

[0081] (ii) Under the same test conditions as in step (i), determine the deposited scale amount S1 after adding different types of scale inhibitors;

[0082] (iii) Calculate the scale inhibition rate based on the reduction in the deposited scale amount with the addition of the scale inhibitor in step (ii) and without the scale inhibitor in step (i), and evaluate the scale inhibition performance of different scale inhibitors;

[0083] (iv) Under the same test conditions as in step (i), determine the deposited scale amount S2 after adding different concentrations of the scale inhibitor;

[0084] (v) Calculate the scale inhibition rates of different concentrations of the scale inhibitor and determine the usage concentration of the scale inhibitor.

[0085] The formula for calculating the scale inhibition rate is: E = (S0 - S2) / S0 × 100%.

[0086] The present invention can simulate the scaling situation and scale prevention effect on the inner wall of a pipeline under the condition of fluid flowing in the pipeline, including: (1) evaluating the influence of factors such as fluid temperature, flow velocity, flow pattern, and water composition on the scaling situation; (2) quantitatively analyzing the proportion of suspended scale and deposited scale on the inner wall of the pipeline in the fluid; (3) observing the morphology of the scale layer on the inner wall of the pipeline and the variation law of the scale layer; (4) evaluating the dynamic scale prevention performance of the scale inhibitor. Using this device to evaluate the performance of the scale inhibitor is closer to the actual production than the static evaluation method used in the petroleum and natural gas industry standard "SY / T5673 Evaluation Method for the Performance of Scale Inhibitors for Oil Fields".

[0087] The applicant declares that the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by any person skilled in the art within the technical scope disclosed by the present invention fall within the protection scope and the disclosure scope of the present invention.

Claims

1. A dynamic scaling simulation experimental device, characterized in that: It includes a water storage tank (1), a metering pump (2), a scaling pipe (3) and a riser pipe (5) which are connected in sequence through connecting pipelines to form a circulation loop; the scaling pipe (3) is placed in an electrothermal constant temperature box (4).

2. The dynamic scaling simulation experimental device according to claim 1, characterized in that: The scaling pipe (3) is communicated with the inlet on the side wall of the riser pipe (5), and the outlet at the top of the riser pipe (5) is communicated with the inlet of the water storage tank (1).

3. The dynamic scaling simulation experimental device according to claim 1, characterized in that: The bottom of the riser pipe (5) is communicated with a transparent conical pipe (6), and the transparent conical pipe (6) gradually reduces in diameter from top to bottom.

4. The dynamic scaling simulation experimental device according to claim 1, characterized in that: A 400-mesh filter screen is arranged at the outlet of the water storage tank (1); a 400-mesh filter screen is arranged at the upper outlet of the riser pipe (5).

5. The dynamic scaling simulation experimental device according to claim 1, characterized in that: The riser pipe (5) is vertically placed.

6. A dynamic scaling simulation experimental analysis method using the dynamic scaling simulation experimental device according to any one of claims 1 to 5, characterized in that: It includes: (Ⅰ) Evaluating the influence of different factors on scaling; (Ⅱ) Quantitatively analyzing suspended scale and deposited scale; (Ⅲ) Evaluating the scale inhibition performance of chemical scale inhibitors.

7. The dynamic scaling simulation experimental analysis method according to claim 6, characterized in that: The specific content of the step (Ⅰ) of evaluating the influence of different factors on scaling includes: (ⅰ) Fixing the fluid composition and the heating temperature of the scaling pipe, changing the flow velocity of the fluid, measuring the scaling conditions at different flow velocities, and then evaluating the influence of the flow velocity and the flow state of the fluid on the scaling conditions; (ⅱ) Fixing the fluid composition and the flow velocity of the fluid, changing the heating temperature of the scaling pipe, measuring the scaling conditions at different heating temperatures of the scaling pipe, and evaluating the influence of the heating temperature of the scaling pipe on the scaling conditions; (ⅲ) Fixing the flow velocity of the fluid and the heating temperature of the scaling pipe, changing the fluid composition, measuring the scaling conditions at different fluid compositions, and evaluating the influence of the fluid composition on the scaling conditions.

8. The dynamic scaling simulation experimental analysis method according to claim 7, characterized in that: The flow state of the fluid is determined by calculating the Reynolds number when the fluid flows, and the calculation formula of the Reynolds number is Re = dvρ / μ; Where: Re is the Reynolds number, dimensionless; d is the diameter of the scaling pipe, in m; ρ is the fluid density, in kg / m 3 ; v is the flow velocity, the unit is m / s; μ is the fluid viscosity, the unit is Pa.s; When the Reynolds number Re < 2300, the flow state of the fluid is laminar flow; When 2300 < Re < 4000, the flow state of the fluid is transitional state; When the Reynolds number Re > 4000, the flow state of the fluid is turbulent flow.

9. The dynamic scaling simulation experimental analysis method according to claim 6, characterized in that: The specific content of the (Ⅱ) of quantitatively analyzing suspended scale and deposited scale includes: (ⅰ) Using the titration analysis method to respectively measure the concentrations of scaling cations at the outlet end and the inlet end of the liquid storage tank, and the sampling time interval of the samples at the outlet end and the inlet end of the liquid storage tank is determined according to the specific experimental situation; (ⅱ) According to the difference in the concentrations of scaling cations at the outlet end and the inlet end of the liquid storage tank, using the equivalent law to calculate the total scaling amount of the system within the above sampling time interval; (ⅲ) Determining the amount of suspended scale according to the amount of scale separated in the riser pipe within the above sampling time interval; (ⅳ) Determining the amount of deposited scale in the scaling pipe within the sampling time interval according to the difference between the total scaling amount and the amount of floating scale.

10. The dynamic scaling simulation experimental analysis method according to claim 6, characterized in that: The specific content of the step (Ⅲ) of evaluating the scale inhibition performance of chemical scale inhibitors includes: (ⅰ) Measuring the amount of deposited scale under the blank condition without adding a scale inhibitor; (ⅱ) Measuring the amount of deposited scale after adding different types of scale inhibitors under the same test conditions as in step (ⅰ); (ⅲ) Calculating the scale inhibition rate according to the reduction in the amount of deposited scale with the addition of the scale inhibitor in step (ⅱ) and without the addition of the scale inhibitor in step (ⅰ), and evaluating the scale inhibition performance of different scale inhibitors; (ⅳ) Measuring the amount of deposited scale after adding the same scale inhibitor at different concentrations under the same test conditions as in step (ⅰ); (v) Calculate the anti-scaling rate of anti-scaling agents of different concentrations and determine the concentration of the anti-scaling agent to be used.

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