Three-stage separation test system and method for high temperature and high pressure crude oil asphaltene precipitation

Abstract

The present invention discloses a three-stage separation test system and method for high-temperature and high-pressure crude oil asphaltene precipitation, the system includes: a booster pump, a temperature control module, a three-stage separator; it also includes a gas cylinder and an oil sample bottle; the temperature control module is provided with a high-temperature and high-pressure reactor; the booster pump is respectively connected to the oil sample bottle and the temperature control module through a multi-way valve; the oil sample bottle and the gas cylinder are connected to the inlet of the high-temperature and high-pressure reactor through a multi-way valve; the outlet of the high-temperature and high-pressure reactor is connected to the inlet of the three-stage separator; the specific method adopts first configuring the required crude oil for simulation, and screening after high-temperature and high-pressure treatment to obtain the asphalt precipitation law. The advantage of the present invention is that the formation condition crude oil is configured by high temperature and high pressure, and finally the crude oil asphaltene precipitation law is tested by a three-stage separation tester, which better restores the actual situation, and also provides theoretical and technical support for oil and gas field prevention and control work, reducing the losses caused by the asphaltene precipitation problem.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas resource development, and in particular to a three-stage separation test system and method for high-temperature and high-pressure crude oil asphaltene precipitation. Background Art

[0002] Oil is a continuous dynamic stability system, similar to a colloid system, in which petroleum hydrocarbons are solvents, asphaltene is micelles, and colloid is a stabilizer. Asphaltene is the component with the largest molecular weight and the strongest polarity in crude oil. It is insoluble in low-order normal alkanes but soluble in solvents such as benzene and toluene. When factors such as temperature, pressure or composition in crude oil change, the dynamic stability system of asphaltene is disturbed or even destroyed, and asphaltene precipitates, aggregates and deposits.

[0003] In the process of production pipelines transporting crude oil from reservoirs to wellheads, or oil pipelines transporting crude oil from wellheads or storage containers to downstream refineries, asphaltene usually precipitates with other solids such as paraffin, causing blockage of downhole pipes and wellbores, blocking oil pipelines and affecting the operation of separation equipment. It often takes a lot of manpower, financial resources and time to restore normal production at the oil field site.

[0004] According to incomplete statistics, in the Shunbei Oil and Gas Field in the Tarim Basin in Xinjiang alone, asphalt blockage occurred in 11 wells, accounting for a quarter of the entire oil field block. Asphalt blockage reduced the wellhead pressure and caused accidents such as obstruction and sticking of test tools, which greatly reduced the production capacity of single wells and even caused oil well shutdown and overhaul operations, seriously affecting the stable production and efficient development of oil wells.

[0005] At present, the influencing factors and precipitation rules of asphaltene precipitation are not clearly understood, and the on-site prevention and control technology in oil fields is weak. There is an urgent need for a research method to clarify the size distribution law of crude oil asphaltene precipitation under high temperature and high pressure conditions, so as to provide a theoretical basis for subsequent treatment measures.

[0006] Patent CN104062244A reports a device for measuring the amount of crude oil asphaltene deposited in porous media and its application. The device includes a horizontal flow pump, a distilled water tank, a crude oil tank, a cyclohexane tank, a toluene tank, a core clamp, a cyclohexane output liquid collection tank, a toluene output liquid collection tank and a UV-visible spectrometer. Since the deposition of asphaltene in the porous medium of the core is divided into two types, one is blocked by the porous medium of the core, and the other is adsorbed on the surface of the core pores. The asphaltene in the crude oil is soluble in toluene, but not in cyclohexane. Therefore, the first injection of cyclohexane is to carry the asphaltene blocked in the porous medium of the test core out of the core, while the asphaltene adsorbed on the surface of the test core pores cannot be smoothly carried out by cyclohexane. When the blocked asphaltene is carried out, toluene is injected again, and the adsorbed asphaltene can be dissolved in toluene, thereby carrying out the adsorbed asphaltene. The method and device can test the quality of asphalt blocked in the pores and the quality of asphalt adsorbed on the surface of the rock pores under the conditions of simulated formation pressure and temperature.

[0007] In summary, the current method for testing the asphaltene deposition in crude oil is to test the total asphaltene deposition, and it is impossible to test the particle size of asphaltene precipitated from crude oil separately under high temperature and high pressure conditions. Therefore, it is necessary to test the particle size distribution law of asphaltene precipitation in crude oil under high temperature and high pressure conditions to provide strong theoretical and technical support for guiding the stable production of oil and gas reservoirs. Summary of the invention

[0008] In view of this, the present invention provides a three-stage separation test system and method for high-temperature and high-pressure crude oil asphaltene precipitation, which can solve the above problems.

[0009] To this end, the present invention is implemented by the following technical solutions.

[0010] A high-temperature and high-pressure crude oil asphaltene precipitation three-stage separation test system, comprising: a booster pump, a temperature control module, and a three-stage separator;

[0011] The three-stage separation test system also includes a gas cylinder and an oil sample bottle; the temperature control module is provided with a high-temperature and high-pressure reactor;

[0012] The booster pump is connected to the inlet of the oil sample bottle and the temperature control module respectively through a multi-way valve; the oil sample bottle and the gas cylinder are connected to the inlet of the high-temperature and high-pressure reactor through a multi-way valve; the outlet of the high-temperature and high-pressure reactor is connected to the inlet of the three-stage separator.

[0013] Furthermore, the filling gas of the gas cylinder is natural gas.

[0014] Furthermore, the upper limit of the working temperature of the high-temperature and high-pressure reactor is 170°C; the upper limit of the working pressure is 60MPa.

[0015] Furthermore, the temperature control module controls the temperature range to be 40°C-170°C.

[0016] Furthermore, it also includes a back pressure controller, which is connected to the outlet of the three-stage separator and adjusts the system pressure working range to 0.1MPa-60MPa.

[0017] Furthermore, it also includes a gas recovery device, which is connected to the outlet of the three-stage separator.

[0018] Furthermore, each stage of the three-stage separator is provided with a sieve; the aperture sizes of the sieves at each stage are different, as follows: the first stage is 150 mesh, with an aperture of 80μm-120μm; the second stage is 300 mesh, with an aperture of 30μm-50μm; the third stage is 600 mesh, with an aperture of 1μm-3μm.

[0019] On the other hand, the present invention also provides a three-stage separation test method for high-temperature and high-pressure crude oil asphaltene precipitation based on the above three-stage separation test system, and the specific method includes:

[0020] S1. First, the degassed crude oil in the oil sample bottle is pumped into a high-temperature and high-pressure reactor, and then the calculated gas is injected into the high-temperature and high-pressure reactor according to the actual gas-oil ratio of the formation;

[0021] S2, heating and pressurizing the temperature control module to the temperature and pressure designed for the experiment, simulating the preparation of formation crude oil;

[0022] S3, turning on the stirring function of the high temperature and high pressure reactor, stirring for a preset time, and then inverting and letting it stand;

[0023] S4, injecting the crude oil in the inverted high-temperature and high-pressure reactor into a three-stage separator to screen out asphaltene precipitates of different particle sizes;

[0024] S5. Wash the asphaltene precipitate with petroleum ether, dry it and weigh it to obtain the mass of asphaltene precipitates with different particle sizes;

[0025] S6. Repeat S1-S5 by changing the temperature and pressure to obtain the particle size distribution law of asphaltene precipitated from the formation crude oil under different temperature and pressure conditions.

[0026] Furthermore, the system also includes a back pressure controller, which is connected to the outlet of the three-stage separator; in S4, different experimental pressures are adjusted by controlling the back pressure controller.

[0027] The present invention has the following advantages:

[0028] The present invention controls pressure and temperature, utilizes a high-temperature and high-pressure reactor to simulate the configuration of formation condition crude oil, and finally uses a three-stage separation tester to effectively test the rules and understanding of crude oil asphaltene precipitation under different temperatures and pressures. Not only does it achieve the total amount of crude oil asphaltene precipitation test under high temperature and high pressure conditions, but it can also quantitatively test the different particle size distribution characteristics of precipitated asphaltene, and better restore the actual situation. Further, combined with the test method, it solves the problem that the current technology cannot test the particle size of crude oil asphaltene precipitation, and also provides theoretical and technical support for the prevention and control of oil and gas fields with serious asphaltene precipitation, avoiding or reducing the losses caused by asphaltene precipitation problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only one or several embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] The distribution positions and distribution numbers of the same structures shown in the drawings are only for the convenience of describing the present invention, rather than indicating or implying that the structures referred to must have specific orientations and distribution numbers, and therefore cannot be understood as limiting the present invention.

[0031] Figure 1 It is a simplified diagram of the system of the present invention;

[0032] Figure 2 The figure is a flow chart of the method of the present invention.

[0033] In the figure:

[0034] 1-boosting pump; 2-gas cylinder; 3-oil sample bottle; 4-temperature control module; 5-high temperature and high pressure reactor; 6-three-stage separator; 7-back pressure controller; 8-gas recovery device. DETAILED DESCRIPTION

[0035] In order to make the purpose and features of the present invention more obvious and understandable, the specific implementation methods of the present invention are further described below in conjunction with the accompanying drawings.

[0036] A high-temperature and high-pressure crude oil asphaltene precipitation three-stage separation test system mainly comprises: a booster pump 1, a temperature control module 4, and a three-stage separator 6; preferably, each stage of the three-stage separator 6 is provided with a screen; the aperture sizes of the screens at each stage are different from each other, in order: the first stage is 150 mesh, with an aperture of 80μm-120μm; the second stage is 300 mesh, with an aperture of 30μm-50μm; the third stage is 600 mesh, with an aperture of 1μm-3μm.

[0037] The three-stage separation test system also includes a gas cylinder 2 and an oil sample bottle 3; the temperature control module 4 is a temperature control system, which is provided with a high-temperature and high-pressure reactor 5; preferably, the upper limit of the working temperature of the high-temperature and high-pressure reactor 5 is 170°C; the upper limit of the working pressure is 60MPa; and the temperature control module 4 controls the temperature range to be 40°C-170°C, and can choose to stay at one of the temperatures and maintain it for a long time.

[0038] like Figure 1 As shown, the booster pump 1 is connected to the oil sample bottle 3 and the temperature control module 4 through a multi-way valve. The oil sample bottle 3 and the gas cylinder 2 are connected to the inlet of the high-temperature and high-pressure reactor 5 through the multi-way valve; preferably, the filling gas of the gas cylinder 2 is natural gas to simulate the gas atmosphere in the real formation. The outlet of the high-temperature and high-pressure reactor 5 is connected to the inlet of the three-stage separator 6.

[0039] Preferably, a back pressure controller 7 is also provided in the system, and the back pressure controller 7 is connected to the outlet of the three-stage separator 6 via a multi-way valve, and the system pressure working range can be adjusted to 0.1 MPa-60 MPa.

[0040] Preferably, the system further comprises a gas recovery device 8, which is connected to the outlet of the three-stage separator 6 and is used for recovering waste gas after the experiment.

[0041] The present invention also provides a three-stage separation test method for high temperature and high pressure crude oil asphaltene precipitation based on the above embodiment, such as Figure 2 As shown, the method includes:

[0042] S1, firstly, the degassed crude oil in the oil sample bottle 3 is pumped into the high temperature and high pressure reactor 4, and then the calculated natural gas is injected into the high temperature and high pressure reactor 4 according to the actual gas-oil ratio of the formation;

[0043] S2, heating and pressurizing the high-temperature and high-pressure reactor system to the temperature and pressure designed in the experiment to simulate the preparation of formation crude oil;

[0044] S3, turn on the stirring function of the reactor, stir for 24 hours, then invert and let stand for 24 hours;

[0045] S4, adjusting different experimental pressures by controlling the back pressure controller 7. Injecting the crude oil in the inverted high temperature and high pressure reactor into the three-stage separator 6, the sieves with different aperture sizes in the three-stage separator will screen out asphaltene precipitates with different particle sizes;

[0046] S5. Use petroleum ether to clean the sieve (asphalt is insoluble in petroleum ether), weigh the sieve after drying, and compare it with the original sieve weight to obtain the mass of asphaltene precipitates with different particle sizes;

[0047] S6. Repeat the above experimental steps S1-S5 by changing the temperature and pressure to obtain the particle size distribution law of asphaltene precipitated from the formation crude oil under different temperature and pressure conditions.

[0048] The above specific implementation methods are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to examples, those skilled in the art should understand that the technical solutions of the invention can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A three-stage separation test method for high-temperature and high-pressure crude oil asphaltene precipitation based on a three-stage separation test system, characterized in that the method include: S1. First, the degassed crude oil in the oil sample bottle (3) is pumped into the high-temperature and high-pressure reactor (5). Then, according to the actual gas-oil ratio of the formation, the calculated gas is injected into the high-temperature and high-pressure reactor (5); S2, raising the temperature and pressurizing the temperature control module (4) to the temperature and pressure designed for the experiment, simulating the preparation of formation crude oil; S3, turning on the stirring function of the high temperature and high pressure reaction kettle (5), stirring for a preset time, and then inverting and letting it stand; S4, injecting the crude oil in the inverted high-temperature and high-pressure reactor (5) into a three-stage separator (6) to screen out asphaltene precipitates of different particle sizes; S5. Wash the asphaltene precipitate with petroleum ether, dry it and weigh it to obtain the mass of asphaltene precipitates with different particle sizes; S6, changing the temperature and pressure and repeating S1-S5, the particle size distribution law of asphaltene precipitated from the formation crude oil under different temperature and pressure conditions can be obtained; A high-temperature and high-pressure crude oil asphaltene precipitation three-stage separation test system, comprising: a booster pump (1), a temperature control module (4), and a three-stage separator (6); It also includes a gas cylinder (2) and an oil sample bottle (3); the temperature control module (4) is provided with a high-temperature and high-pressure reaction kettle (5); The booster pump (1) is connected to the oil sample bottle (3) and the temperature control module (4) respectively through a multi-way valve; the oil sample bottle (3) and the gas cylinder (2) are connected to the inlet of the high-temperature and high-pressure reactor (5) through a multi-way valve; the outlet of the high-temperature and high-pressure reactor (5) is connected to the inlet of the three-stage separator (6); Each level of the three-stage separator (6) is provided with a sieve; the aperture sizes of the sieves at each level are different from each other, and are as follows: the first level is 150 mesh, with an aperture of 80 μm-120 μm; the second level is 300 mesh, with an aperture of 30 μm-50 μm; the third level is 600 mesh, with an aperture of 1 μm-3 μm.

2. The three-stage separation test method according to claim 1, characterized in that: The system further comprises a back pressure controller (7), wherein the back pressure controller (7) is connected to the outlet of the three-stage separator (6); and different experimental pressures are adjusted in S4 by controlling the back pressure controller (7).

3. The three-stage separation test method according to claim 1, characterized in that: The gas filled in the gas cylinder (2) is natural gas.

4. The three-stage separation test method according to claim 1, characterized in that: The upper limit of the working temperature of the high temperature and high pressure reactor (5) is 170° C.; the upper limit of the working pressure is 60 MPa.

5. The three-stage separation test method according to claim 4, characterized in that: The temperature control module (4) controls the temperature range to be 40°C-170°C.

6. The three-stage separation test method according to claim 1, characterized in that: It also includes a back pressure controller (7), which is connected to the outlet of the three-stage separator (6) and adjusts the system pressure working range to 0.1 MPa-60 MPa.

7. The three-stage separation test method according to claim 1, characterized in that: It also comprises a gas recovery device (8), wherein the gas recovery device (8) is connected to the outlet of the three-stage separator (6).

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