An experimental device and method for testing the freezing point of super-low freezing point condensate oil

Abstract

The application discloses a kind of super-low freezing point condensate oil freezing point test experimental device and method, the experimental device includes support system, cooling system, sample placement system, temperature testing device;The sample placement system includes glass test tube and the sealing plug of sealing the glass test tube, the glass test tube is used to hold condensate oil to be tested, and the lower part of the glass test tube is equipped with three parallelly arranged scale lines A, B, C from bottom to top;The temperature testing device is used for testing the temperature of the condensate oil to be tested by passing through the sealing plug;The cooling system includes glass sleeve, isolation glass bottle, open glass bottle, the glass test tube is arranged in the glass sleeve, the glass sleeve is arranged in the isolation glass bottle, and the isolation glass bottle is arranged in the open glass bottle;The support system has height adjustment and rotation function.The application can predict freezing point in advance, and can efficiently test the freezing point of super-low freezing point condensate oil.

Description

Technical Field

[0001] This invention relates to the field of oil and gas field development technology, and in particular to an experimental apparatus and method for testing the pour point of ultra-low pour point condensate. Background Technology

[0002] During the development of condensate gas fields, condensate oil is produced. This oil needs to be separated and processed before being transported via long-distance pipelines and other means to various industrial applications. In extremely cold regions or certain industrial applications, it is necessary to determine the pour point of the condensate oil to prevent blockages caused by condensation.

[0003] Current technologies for testing the pour point of crude oil mainly target conventional crude oil and general light oils. They lack methods for predicting pour points and rely solely on slow, incremental cooling, which is time-consuming—reducing temperature from room temperature to -40°C takes several hours, and further cooling is even slower and less efficient. The cooling process also consumes significant amounts of electricity, which is not energy-efficient or environmentally friendly. Furthermore, the achievable temperature range is insufficient for testing the pour point of some ultra-low pour point condensates. Within this temperature range, the condensate samples do not show signs of condensation, making it impossible to determine their pour point. For such ultra-low pour point condensates, current technologies are inadequate, necessitating the exploration of new experimental methods.

[0004] Furthermore, existing condensate oil pour point testing apparatuses have long cooling times. When the temperature drops to a certain level, the cooling becomes very slow, making the experiment time-consuming. Moreover, the achievable testing temperature range is insufficient for some light oils with low pour points, and even less suitable for condensate oils with extremely low pour points. During testing, the setpoint of the low-temperature water supply unit at the end of the test is taken as the pour point of the crude oil. However, due to energy loss during energy transfer between the cooling medium and the crude oil in the test tube, the actual temperature of the crude oil will always be higher than that of the cooling medium outside the test tube, leading to an overestimation of the test results. Summary of the Invention

[0005] To address the aforementioned problems, this invention aims to provide an experimental apparatus and method for testing the pour point of ultra-low pour point condensate oil.

[0006] The technical solution of the present invention is as follows:

[0007] On the one hand, an experimental apparatus for testing the pour point of ultra-low pour point condensate is provided, including a support system, a cooling system, a sample placement system, and a temperature testing device;

[0008] The sample placement system includes a glass test tube and a sealing plug for sealing the glass test tube. The glass test tube is used to hold the condensate oil to be tested, and the lower part of the glass test tube is provided with three parallel markings A, B, and C arranged from bottom to top.

[0009] The temperature testing device passes through the sealing plug to test the temperature of the condensate oil to be tested;

[0010] The cooling system includes a glass sleeve, an insulating glass bottle, and an open glass bottle. The glass test tube is placed inside the glass sleeve, the glass sleeve is placed inside the insulating glass bottle, and the insulating glass bottle is placed inside the open glass bottle. The glass sleeve contains an insulating medium one, the insulating glass bottle contains an insulating medium two, and the open glass bottle contains a cooling medium.

[0011] The support system includes a support frame and a bracket. The support frame has a height adjustment function, and the open glass bottle is placed on the support frame. The bracket has a rotation function, with one end connected to the support frame and the other end connected to the glass sleeve.

[0012] Preferably, the temperature testing device is a thermometer, and the sealing plug is a rubber plug.

[0013] As a preferred option, the three marking lines are distributed at equal intervals.

[0014] Preferably, the interval between two adjacent markings is 1.5 mm.

[0015] Preferably, both the first and second isolation media are alcohol, and the cooling medium is liquid ammonia.

[0016] Preferably, the support system further includes a knob disposed on the support frame, through which the support is rotated.

[0017] On the other hand, a method for testing the pour point of ultra-low pour point condensate oil is also provided, which uses the pour point testing apparatus for ultra-low pour point condensate oil described in any one of the above-mentioned methods, and includes the following steps:

[0018] S1: Predict the pour point of the condensate oil to be tested, and obtain the predicted pour point of the condensate oil to be tested;

[0019] S2: The condensate oil to be tested is loaded into the glass test tube, the glass test tube is sealed with the sealing plug, the temperature testing device is inserted into the glass test tube, and it is ensured that after the temperature testing device is loaded, the interface of the condensate oil to be tested is flush with the mark A.

[0020] S3: Inject the first isolation medium into the glass sleeve, and make the interface of the first isolation medium higher than the mark C;

[0021] S4: Inject the second isolation medium into the isolation glass bottle, and make the interface of the second isolation medium higher than the interface of the first isolation medium, or flush with the interface of the first isolation medium.

[0022] S5: Continuously add the cooling medium to the open glass bottle, and observe the temperature change measured by the temperature testing device, as well as the color and state changes of the condensate oil to be tested:

[0023] When the temperature measured by the temperature testing device differs from the predicted freezing point by a threshold temperature, the rate of addition of the cooling medium is reduced.

[0024] When the color of the condensate oil to be tested changes to milky white or light brown, proceed to step S6;

[0025] S6: Adjust the height of the support frame so that the mark A of the glass test tube is higher than the interface of the cooling medium;

[0026] S7: Rotate the bracket so that the glass sleeve and the glass test tube rotate together, and the angle after rotation forms an acute angle with the horizontal plane;

[0027] If the interface of the condensate oil to be tested is located between line A and line B within the time threshold, then the temperature measured by the temperature testing device at this time is the pour point of the condensate oil to be tested.

[0028] If, within the time threshold, the interface of the condensate oil to be tested exceeds line B and is located between lines A and C, or intersects with all three lines, then rotate the support to restore it to a vertical state, adjust the height of the support frame to restore the interface state, and repeat steps S5-S7.

[0029] Preferably, in step S1, the pour point of the condensate oil to be tested is predicted using the following formula:

[0030] T n =56.511ln(α)-306.36 (1)

[0031] In the formula: T n α represents the predicted pour point of the condensate oil to be tested, in °C; α represents the molar content of heavy aromatics (aromatics with more than C10) in the condensate oil to be tested, in °C.

[0032] Preferably, in step S7, the acute angle is 45° and the time threshold is 15s.

[0033] Preferably, in step S7, when the interface of the condensate oil to be tested exceeds line B and is located between line A and line C, the cooling rate after returning to step S5 is lower than the cooling rate after returning to step S5 when the interface of the condensate oil to be tested intersects all three lines.

[0034] The beneficial effects of this invention are:

[0035] This invention can meet the requirements for pour point testing at temperatures below -60℃ or even lower, and can predict the pour point in advance, greatly improving testing efficiency. Existing technologies require several hours to test samples with very low pour points, while this invention can generally complete the test within half an hour to an hour, and skilled operators can even complete it within half an hour, improving efficiency several times over. The experimental method described in this invention is convenient and efficient to operate, resulting in good experimental repeatability and providing technical support for the development of condensate gas fields. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the experimental apparatus for testing the pour point of ultra-low pour point condensate oil according to the present invention.

[0038] Figure 2 This is a schematic diagram of the glass test tube structure of the experimental apparatus for testing the pour point of ultra-low pour point condensate oil according to the present invention.

[0039] The following numbers are labeled in the diagram: 1-Support frame, 2-Knob, 3-Bracket, 4-Sealing plug, 5-Temperature testing device, 6-Glass test tube, 7-Glass sleeve, 8-Isolation glass bottle, 9-Open glass bottle, 10-Cooling medium, 11-Isolation medium II, 12-Isolation medium I, 13-Condensate oil to be tested. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and technical features described in this application can be combined with each other. It should also be pointed out that, unless otherwise indicated, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. The terms "comprising" or "including" and similar words used in this invention refer to elements or objects preceding the word that encompass the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0041] On the one hand, such as Figure 1-2 As shown, the present invention provides an experimental apparatus for testing the pour point of ultra-low pour point condensate oil, including a support system, a cooling system, a sample placement system, and a temperature testing device 5.

[0042] The sample placement system includes a glass test tube 6 and a sealing plug 4 for sealing the glass test tube 6. The glass test tube 6 is used to hold the condensate oil 13 to be tested, and the lower part of the glass test tube 6 is provided with three parallel markings A, B and C arranged from bottom to top.

[0043] The temperature testing device 5 passes through the sealing plug 4 to test the temperature of the condensate oil 13 to be tested;

[0044] The cooling system includes a glass sleeve 7, an isolation glass bottle 8, and an open glass bottle 9. The glass test tube 6 is placed inside the glass sleeve 7, the glass sleeve 7 is placed inside the isolation glass bottle 8, and the isolation glass bottle 8 is placed inside the open glass bottle 9. The glass sleeve 7 contains an isolation medium 12, the isolation glass bottle 8 contains an isolation medium 11, and the open glass bottle 9 contains a cooling medium 10.

[0045] The support system includes a support frame 1 and a bracket 3. The support frame 1 has a height adjustment function, and the open glass bottle 9 is mounted on the support frame 1. The bracket 3 has a rotation function, with one end connected to the support frame 1 and the other end connected to the glass sleeve 7.

[0046] In one specific embodiment, the temperature testing device 5 is a thermometer; the sealing plug 4 is a rubber stopper; the three markings are evenly spaced, with a 1.5mm interval between adjacent markings; both the first isolation medium 12 and the second isolation medium 11 are alcohol, and the cooling medium 10 is liquid ammonia. Optionally, to make the three markings clearer, the three markings are set to easily identifiable colors, and each marking is a different color.

[0047] In the above embodiment, the interval between two adjacent markings is set to 1.5 mm because condensate oil in its condensed state is close to solid. If the interface deviation exceeds 1.5 mm within a short period of time during observation, it is clear that the pour point has not yet been reached. A spacing that is too large is meaningless, while a spacing that is too small is inconvenient for observation. This value is the result of the inventor's creative efforts, achieving a value that is both easy to observe and allows for accurate measurement of the condensate oil's pour point.

[0048] In one specific embodiment, the support system further includes a knob 2 disposed on the support frame 1, and the bracket 3 is rotated by the knob 2.

[0049] It should be noted that height-adjustable support frames and brackets that can be rotated via knobs are existing technologies, and their specific structures will not be described in detail here.

[0050] On the other hand, the present invention also provides a method for testing the pour point of ultra-low pour point condensate oil, which uses the pour point testing apparatus for ultra-low pour point condensate oil described in any one of the above-mentioned methods, and includes the following steps:

[0051] S1: Predict the pour point of the condensate oil 13 to be tested, and obtain the predicted pour point of the condensate oil 13 to be tested.

[0052] In one specific embodiment, the pour point of the condensate oil 13 to be tested is predicted by the following formula:

[0053] T n =56.511ln(α)-306.36 (1)

[0054] In the formula: T n α represents the predicted pour point of the condensate oil to be tested, in °C; α represents the molar content of heavy aromatics (aromatics with more than C10) in the condensate oil to be tested, in °C.

[0055] In this embodiment, the inventors innovatively discovered that there is a relatively good correlation between the pour point of condensate oil and the molar content of C10+. The pour point of the condensate oil to be tested can be predicted quickly and effectively through the fitting formula of equation (1), providing an expected temperature anchor point for the subsequent pour point test of the condensate oil to be tested.

[0056] S2: The condensate oil 13 to be tested is loaded into the glass test tube 6, the glass test tube 6 is sealed with the sealing plug 4, the temperature testing device 5 is inserted into the glass test tube 6, and it is ensured that after the temperature testing device 5 is loaded, the interface of the condensate oil 13 to be tested is flush with the mark A.

[0057] In one specific embodiment, a syringe is used to draw and inject the condensate oil to be tested. This allows for more precise control of the injection volume, ensuring that the interface is flush with mark A. It is worth noting that when inserting the temperature testing device 5, it should be positioned as centrally as possible within the glass test tube 6 to avoid contact between the device and the tube, which could affect the accuracy of the temperature readings.

[0058] S3: Inject the first isolation medium into the glass sleeve, and make the interface of the first isolation medium higher than the mark C.

[0059] S4: Inject the second isolation medium into the isolation glass bottle, and make the interface of the second isolation medium higher than or flush with the interface of the first isolation medium.

[0060] S5: Continuously add the cooling medium to the open glass bottle, and observe the temperature change measured by the temperature testing device, as well as the color and state changes of the condensate oil to be tested:

[0061] When the temperature measured by the temperature testing device differs from the predicted freezing point by a threshold temperature, the rate of addition of the cooling medium is reduced.

[0062] When the color of the condensate oil to be tested changes to milky white or light brown, proceed to step S6.

[0063] In one specific embodiment, if the temperature change observed in this step is too rapid, it can be regulated by reducing the rate of addition of the cooling medium, or by adding isolation medium one or isolation medium two again.

[0064] S6: Adjust the height of the support frame so that the mark A of the glass test tube is higher than the interface of the cooling medium.

[0065] S7: Rotate the bracket so that the glass sleeve and the glass test tube rotate together, and the angle after rotation forms an acute angle with the horizontal plane;

[0066] If the interface of the condensate oil to be tested is located between line A and line B within the time threshold, then the temperature measured by the temperature testing device at this time is the pour point of the condensate oil to be tested.

[0067] If, within the time threshold, the interface of the condensate oil to be tested exceeds line B and is located between lines A and C, or intersects with all three lines, then rotate the support to restore it to a vertical state, adjust the height of the support frame to restore the interface state, and repeat steps S5-S7.

[0068] In one specific embodiment, the acute angle is 45° and the time threshold is 15 seconds. It should be noted that the angle and time in this embodiment are only preferred values; the time threshold can be adjusted accordingly for different acute angles.

[0069] In one specific embodiment, when the interface of the condensate oil to be tested exceeds line B and is located between line A and line C, the cooling rate after returning to step S5 is lower than the cooling rate after returning to step S5 when the interface of the condensate oil to be tested intersects all three lines.

[0070] In one specific embodiment, the pour point test method for ultra-low pour point condensate oil described in this invention was used to test the pour point of each condensate oil to be tested, and the results are shown in Table 1:

[0071] Table 1. Results of Pour Point Tests on Condensate Oil.

[0072] Serial Number Color of condensate oil to be tested Sample Description C10+ molar content (%) Predicted pour point (°C) Test pour point (°C) 1 pale yellow Clear and transparent 82.87 -56.73 -55 2 pale yellow Clear and transparent 84.09 -55.91 -57 3 pale yellow Clear and transparent 90.96 -51.47 -55 4 pale yellow Clear and transparent 84.05 -55.94 -53 5 colorless Clear and transparent 83.70 -56.17 -55 6 pale yellow Clear and transparent 83.59 -56.25 -57 7 pale yellow Clear and transparent 91.05 -51.41 -51 8 pale yellow Clear and transparent 87.67 -53.56 -55 9 colorless Clear and transparent 88.08 -53.29 -53 10 pale yellow Clear and transparent 89.78 -52.21 -50 11 pale yellow Clear and transparent 84.53 -55.61 -54 12 pale yellow Clear and transparent 90.45 -51.79 -55 13 yellow Mild turbidity 86.55 -54.28 -58 14 pale yellow Mild turbidity 85.74 -54.81 -54 15 pale yellow Clear and transparent 87.04 -53.96 -54 16 pale yellow Clear and transparent 87.62 -53.58 -53 17 black Severe turbidity 89.08 -52.65 -56

[0073] Because the thermometer used in this embodiment is a low-temperature thermometer capable of testing ultra-low temperatures of -100℃ and with an accuracy of 1℃, the final pour point of the condensate oil to be tested is an integer.

[0074] As can be seen from Table 1, the condensate oil pour point prediction method shown in Equation (1) can predict the pour point of the condensate oil to be tested relatively accurately, with an error within 5℃. In this embodiment, the time required to obtain the pour point of each condensate oil sample to be tested is relatively short, and the test of each sample can be completed in 20min-60min, which greatly improves the efficiency compared with the traditional pour point test method.

[0075] In summary, this invention can scientifically and accurately quantify the pour point of ultra-low pour point condensate oil, providing important evidence for determining whether condensation blockage will occur in pipeline transportation in extremely cold regions or in certain industrial applications. The invention proposes a novel method for determining whether an ultra-low pour point condensate oil sample has reached its pour point; it is simple to operate, highly repeatable, and easily identifiable for various states. This invention significantly improves testing efficiency, reaching several times that of existing technologies, and can quickly determine the pour point of ultra-low pour point condensate oil. The experimental apparatus designed in this invention does not require a complex system, has low cost, and does not consume large amounts of electricity, thus contributing to energy conservation and environmental protection. Compared with existing technologies, this invention represents a significant advancement.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for testing the pour point of ultra-low pour point condensate oil, characterized in that, The pour point test was conducted using an ultra-low pour point condensate oil pour point test apparatus; the pour point test apparatus includes a support system, a cooling system, a sample placement system, and a temperature test device. The sample placement system includes a glass test tube and a sealing plug for sealing the glass test tube. The glass test tube is used to hold the condensate oil to be tested, and the lower part of the glass test tube is provided with three parallel markings A, B, and C arranged from bottom to top. The temperature testing device passes through the sealing plug to test the temperature of the condensate oil to be tested; The cooling system includes a glass sleeve, an insulating glass bottle, and an open glass bottle. The glass test tube is placed inside the glass sleeve, the glass sleeve is placed inside the insulating glass bottle, and the insulating glass bottle is placed inside the open glass bottle. The glass sleeve contains an insulating medium one, the insulating glass bottle contains an insulating medium two, and the open glass bottle contains a cooling medium. The support system includes a support frame and a bracket. The support frame has a height adjustment function, and the open-mouthed glass bottle is mounted on the support frame. The bracket has a rotation function, with one end connected to the support frame and the other end connected to the glass sleeve. The freezing point test method includes the following steps: S1: The predicted pour point of the condensate oil to be tested is obtained by predicting the pour point using the following formula: （1） In the formula: T n α represents the predicted pour point of the condensate oil to be tested, in °C; α represents the molar content of heavy aromatics in the condensate oil to be tested, in %; S2: The condensate oil to be tested is loaded into the glass test tube, the glass test tube is sealed with the sealing plug, the temperature testing device is inserted into the glass test tube, and it is ensured that after the temperature testing device is loaded, the interface of the condensate oil to be tested is flush with the mark A. S3: Inject the first isolation medium into the glass sleeve, and make the interface of the first isolation medium higher than the mark C; S4: Inject the second isolation medium into the isolation glass bottle, and make the interface of the second isolation medium higher than the interface of the first isolation medium, or flush with the interface of the first isolation medium. S5: Continuously add the cooling medium to the open glass bottle, and observe the temperature change measured by the temperature testing device, as well as the color and state changes of the condensate oil to be tested: When the temperature measured by the temperature testing device differs from the predicted freezing point by a threshold temperature, the rate of addition of the cooling medium is reduced. When the color of the condensate oil to be tested changes to milky white or light brown, proceed to step S6; S6: Adjust the height of the support frame so that the mark A of the glass test tube is higher than the interface of the cooling medium; S7: Rotate the bracket so that the glass sleeve and the glass test tube rotate together, and the angle after rotation forms an acute angle with the horizontal plane; If the interface of the condensate oil to be tested is located between line A and line B within the time threshold, then the temperature measured by the temperature testing device at this time is the pour point of the condensate oil to be tested. If, within the time threshold, the interface of the condensate oil to be tested exceeds line B and is located between lines A and C, or intersects with all three lines, then rotate the support to restore it to a vertical state, adjust the height of the support frame to restore the interface state, and repeat steps S5-S7.

2. The method for testing the pour point of ultra-low pour point condensate oil according to claim 1, characterized in that, The temperature testing device uses a thermometer, and the sealing plug uses a rubber plug.

3. The method for testing the pour point of ultra-low pour point condensate oil according to claim 1, characterized in that, The three marking lines are evenly spaced.

4. The method for testing the pour point of ultra-low pour point condensate oil according to claim 3, characterized in that, The interval between two adjacent markings is 1.5mm.

5. The method for testing the pour point of ultra-low pour point condensate oil according to claim 1, characterized in that, Both the first and second isolation media are made of alcohol, and the cooling medium is made of liquid ammonia.

6. The method for testing the pour point of ultra-low pour point condensate oil according to claim 1, characterized in that, The support system also includes a knob disposed on the support frame, through which the support can be rotated.

7. The method for testing the pour point of ultra-low pour point condensate oil according to claim 1, characterized in that, In step S7, the acute angle is 45° and the time threshold is 15s.

8. The method for testing the pour point of ultra-low pour point condensate oil according to claim 1, characterized in that, In step S7, when the interface of the condensate oil to be tested exceeds line B and is located between line A and line C, the cooling rate after returning to step S5 is lower than the cooling rate after returning to step S5 when the interface of the condensate oil to be tested intersects all three lines.

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