CN114428046A - Microscopic experimental device and method for testing asphaltene deposition - Google Patents
Microscopic experimental device and method for testing asphaltene deposition Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000012360 testing method Methods 0.000 title claims abstract description 32
- 238000005530 etching Methods 0.000 claims abstract description 194
- 239000007788 liquid Substances 0.000 claims abstract description 107
- 238000002347 injection Methods 0.000 claims abstract description 87
- 239000007924 injection Substances 0.000 claims abstract description 87
- 238000006243 chemical reaction Methods 0.000 claims abstract description 60
- 230000035699 permeability Effects 0.000 claims abstract description 37
- 239000012530 fluid Substances 0.000 claims abstract description 35
- 238000002474 experimental method Methods 0.000 claims abstract description 16
- 239000012780 transparent material Substances 0.000 claims abstract description 4
- 239000010779 crude oil Substances 0.000 claims description 60
- 239000003921 oil Substances 0.000 claims description 35
- 230000015572 biosynthetic process Effects 0.000 claims description 27
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- 229920006395 saturated elastomer Polymers 0.000 claims description 8
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- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 12
- 230000035515 penetration Effects 0.000 description 12
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N15/00—Investigating characteristics of particles; Investigating permeability, pore-volume, or surface-area of porous materials
- G01N15/08—Investigating permeability, pore-volume, or surface area of porous materials
- G01N15/082—Investigating permeability by forcing a fluid through a sample
- G01N15/0826—Investigating permeability by forcing a fluid through a sample and measuring fluid flow rate, i.e. permeation rate or pressure change
Abstract
The invention discloses a microscopic experimental device and a microscopic experimental method for testing asphaltene deposition, wherein the microscopic experimental device comprises the following steps: the microscopic etching model is made of transparent materials, a plurality of permeation areas are etched in the microscopic etching model, a liquid inlet and a liquid outlet are respectively arranged at two ends of the microscopic etching model, and the plurality of permeation areas are positioned on the same plane and connected between the liquid inlet and the liquid outlet in parallel; the injection device is used for injecting fluid into the micro-etching model; the metering device is used for measuring the gas-liquid ratio of the fluid produced by the micro etching model; the back pressure valve is used for adjusting the pressure in the micro etching model; the reaction kettle is connected with a temperature control system and a vacuum pump, a window is arranged on a top cover of the reaction kettle, the micro-etching model is sealed in the reaction kettle, and a plurality of permeation areas of the micro-etching model face the window; the image acquisition device acquires the image of the micro-etching model through the window. The method is used for accurately, quickly, efficiently and visually determining the deposition condition of the asphaltene and the permeability limit of the deposition of the asphaltene under the condition of the high-temperature high-pressure porous medium.
Description
Technical Field
The invention belongs to the field of petroleum development experiments, and particularly relates to a microscopic experiment device and method for testing asphaltene deposition.
Background
Asphaltenes are an important component of crude oil in oil reservoirs, and in the process of primary oil recovery and gas drive enhanced oil recovery, the asphaltene can be precipitated due to the change of temperature and pressure, and the precipitation can occur in the oil reservoirs, and can also occur in equipment such as wellholes, separators, surface pipelines, oil tanks and the like. If the deposition of the asphaltene occurs in the oil reservoir, the precipitated asphaltene can be adsorbed on the surface of the rock, so that the wettability of the rock is changed, and even the pore throat of the stratum is blocked, thereby reducing the oil displacement efficiency. Therefore, for oil reservoirs with high asphaltene content, the determination of asphaltene deposition rules is one of important works for determining whether the oil reservoirs can be effectively developed.
In order to deeply know the deposition rule of the formation pressure and injected gas composition on the asphaltene under reservoir conditions and determine the permeability limit of asphaltene deposition, influence factor research needs to be carried out from a microscopic perspective, so that a microscopic etching model is essential.
Although the existing microscopic etching model is simple to manufacture and low in cost, the interlayer heterogeneity characteristic is not considered, the reservoir permeability limit of asphaltene deposition can be determined only through a large number of experiments, and the microscopic action process of injected media and crude oil is not easy to observe.
Therefore, the research and development of a microscopic experimental device and a method for testing asphaltene deposition are expected to solve the problem of researching the influence of the porous medium on the deposition rule of crude oil asphaltene under the high-temperature and high-pressure conditions, and accurately, quickly, efficiently and intuitively determine the asphaltene deposition condition under the high-temperature and high-pressure porous medium condition and the permeability limit of asphaltene deposition in a heterogeneous reservoir.
Disclosure of Invention
The invention aims to provide a microscopic experimental device and a microscopic experimental method for testing asphaltene deposition, which are used for researching the influence of high-temperature high-pressure porous medium on the asphaltene deposition rule of crude oil.
In order to achieve the above object, the present invention provides a microscopic experimental apparatus for testing asphaltene deposition, comprising:
the micro-etching model is made of transparent materials, a plurality of permeation areas are etched in the micro-etching model, a liquid inlet and a liquid outlet are respectively arranged at two ends of the micro-etching model, and the permeation areas are located on the same plane and connected between the liquid inlet and the liquid outlet in parallel;
the injection device is connected with the liquid inlet of the micro-etching model and is used for injecting fluid into the micro-etching model;
the metering device is connected to the liquid outlet of the micro etching model and is used for measuring the gas-liquid ratio of the fluid produced by the micro etching model;
the back pressure valve is arranged between the metering device and the liquid outlet of the micro etching model and is used for adjusting the pressure in the micro etching model;
the reaction kettle is connected with a temperature control system and a vacuum pump, a window is arranged on a top cover of the reaction kettle, the micro-etching model is sealed in the reaction kettle, and a plurality of permeation areas of the micro-etching model face the window;
and the image acquisition device acquires the image of the micro etching model through the window.
Optionally, the micro-etching model comprises ground glass and plate glass;
the liquid inlet and the liquid outlet are respectively etched from two ends of the ground glass to the middle part on the top surface of the ground glass, and a plurality of flow channels are etched between the liquid inlet and the liquid outlet in parallel;
the plurality of permeation regions are etched on the top surface of the ground glass, and each permeation region is communicated with one flow channel;
the plate glass covers the top surface of the ground glass.
Optionally, each permeation region is in a groove shape, a plurality of circular concave grooves for simulating pores are distributed on the bottom surface of each groove, and the sizes of the circular concave grooves in the plurality of permeation regions are the same or different;
the outline of each permeation area is rectangular, one side of each permeation area is parallel to the extending direction of the flow channel and is overlapped with the flow channel, and the other sides of each permeation area are closed.
Optionally, the injection device comprises two injection pumps and two intermediate containers, wherein one of the injection pumps is connected to the liquid inlet of the micro etching model through one of the intermediate containers, and a valve is arranged between the intermediate container and the liquid inlet of the micro etching model;
the other injection pump is connected to the reaction kettle through the other intermediate container.
Optionally, the back pressure valve is connected to a back pressure pump, and a valve is arranged between the back pressure valve and the metering device.
Optionally, the metering device comprises a gas-liquid separator and a liquid measuring pipe, the inlet end of the gas-liquid separator is connected to the back pressure valve, the liquid outlet end of the gas-liquid separator is connected to the liquid measuring pipe, and the gas outlet end of the gas-liquid separator is provided with a pressure gauge.
Optionally, the image acquisition device includes a bottom lamp, a camera and an image processor, the bottom lamp is disposed below the reaction kettle, and the camera is disposed above the window and connected to the image processor.
An experimental method for testing asphaltene deposition, which utilizes the above microscopic experimental apparatus for testing asphaltene deposition, the method comprising the steps of:
1) sealing the micro-etching model in the reaction kettle;
2) vacuumizing the reaction kettle and the interior of the micro etching model by using the vacuum pump;
3) injecting a fluid medium into the micro-etching model by using the injection device, and injecting saturated deionized water into the reaction kettle simultaneously to increase the pressure inside the micro-etching model and the reaction kettle to be higher than the bubble point pressure of the target reservoir crude oil;
4) keeping the pressure constant, and heating the temperature inside the reaction kettle to the target oil reservoir temperature by using the temperature control system;
5) injecting saturated simulated formation crude oil into the micro-etching model by using the injection device, so that the plurality of permeation regions are filled with the simulated formation crude oil;
6) and reducing the temperature inside the micro etching model and the reaction kettle and the pressure inside the micro etching model to a target temperature and a target pressure, and then displacing the simulated formation crude oil by using a displacement fluid, or directly injecting gas into the micro etching model to displace the formation crude oil, and capturing residues in the micro etching model by using the image acquisition device.
Optionally, the step 6) includes:
6.1) reducing the temperature inside the microscopic etching model and the reaction kettle and the pressure inside the microscopic etching model step by using the temperature control system and the back pressure valve to a target temperature and a target pressure and maintaining the temperature and the pressure stable;
6.2) injecting a displacement fluid into the micro etching model by using an injection device, and capturing the color change of the crude oil in the micro etching model by using the image acquisition device in the injection process until the color does not change any more;
6.3) if no residue exists in the micro-etching model, returning to the step 5), and changing the target temperature and the target pressure; and if residues are left in the micro-etching model, capturing the residues in the micro-etching model by using the image acquisition device, wherein the current temperature and pressure are the starting point of asphaltene precipitation, and the permeability corresponding to the permeation area with the residues is the boundary of the deposition permeability at the current temperature and pressure.
Optionally, the step 6) includes:
6.1) injecting gas into the micro etching model by using the injection device, wherein the gas injection pressure is gradually increased from low to high, and the color change of crude oil in the model is continuously captured in the gas injection process;
6.2) stopping gas injection when the gas-liquid ratio of the produced fluid in the micro etching model is not less than 3000 according to the measurement result of the metering device after the color of the crude oil is not changed any more;
6.3) injecting a displacement fluid into the micro etching model by using the injection device, capturing the color change of the crude oil in the model in the injection process, and stopping injecting the displacement fluid until the color and the state are not changed any more;
6.4) if no residue exists in the micro etching model, returning to the step 5), and increasing the injection pressure of the gas; and if residues are left in the micro-etching model, capturing the residues in the micro-etching model by using the image acquisition device, wherein the current temperature and gas injection pressure are the starting points of asphaltene precipitation in the gas drive process, and the permeability corresponding to the permeability zone where the residues are left is the boundary of the precipitation permeability at the current temperature and gas injection pressure in the gas drive process.
The invention has the beneficial effects that:
1. injecting simulated formation oil into the microscopic etching model, controlling the temperature and pressure in the reaction kettle and the microscopic etching model by using a temperature control system and a back pressure valve, displacing the simulated formation oil after the temperature and pressure of the device are stabilized, and capturing the color change of crude oil and whether the microscopic etching model contains residues by using an image acquisition device, so that the experimental efficiency is high and the experimental result is more visual; the device can perform multiple experiments on the simulated formation oil, and accurately, quickly, efficiently and intuitively determine the initial point of asphaltene deposition and the limit of deposition permeability by changing the temperature, the pressure and the gas injection conditions; the device can be repeatedly used, the actual core of the oil reservoir can be simulated in the microscopic etching model to set the penetration zones with different permeabilities, and the asphaltene deposition rule in the actual core of the oil reservoir can be more accurately obtained.
2. The method is convenient to implement, and can accurately, quickly, efficiently and visually determine the temperature and pressure conditions and the deposition permeability limit of the deposition of the asphaltene as well as the temperature and pressure conditions and the deposition permeability limit of the deposition of the asphaltene in the gas flooding process.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.
FIG. 1 shows a schematic structural diagram flow diagram of a microscopic experimental setup for testing asphaltene deposition according to one embodiment of the present invention.
FIG. 2 shows a schematic block diagram of a microetching model according to one embodiment of the invention.
Description of the reference numerals
1. Micro-etching the model; 2. a reaction kettle; 3. a back pressure valve; 4. a valve; 5. an injection pump; 6. an intermediate container; 7. a vacuum pump; 8. a temperature control system; 9. a camera; 10. an image processor; 11. a gas-liquid separator; 12. a liquid amount measuring tube; 13. a sapphire window; 14. a seal ring; 15. a bolt; 16. a bottom lamp.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.
The invention discloses a microscopic experimental device for testing asphaltene deposition, which comprises:
the micro-etching model is made of transparent materials, a plurality of permeation areas are etched in the micro-etching model, a liquid inlet and a liquid outlet are respectively arranged at two ends of the micro-etching model, and the permeation areas are located on the same plane and connected between the liquid inlet and the liquid outlet in parallel;
the injection device is connected with the liquid inlet of the micro-etching model and is used for injecting fluid into the micro-etching model;
the metering device is connected to the liquid outlet of the micro-etching model and is used for measuring the gas-liquid ratio of the fluid produced by the micro-etching model;
the back pressure valve is arranged between the metering device and the liquid outlet of the micro etching model and is used for adjusting the pressure in the micro etching model;
the reaction kettle is connected with a temperature control system and a vacuum pump, a window is arranged on a top cover of the reaction kettle, the micro-etching model is sealed in the reaction kettle, and a plurality of permeation areas of the micro-etching model face the window;
and the image acquisition device acquires the image of the micro etching model through the window.
Specifically, the simulated formation oil is injected into the microscopic etching model, the temperature and the pressure in the reaction kettle and the microscopic etching model are controlled by using the temperature control system and the back pressure valve, the simulated formation oil is displaced after the temperature and the pressure of the device are stabilized, and the color change of the crude oil and whether the microscopic etching model contains residues are captured by using the image acquisition device, so that the device is high in experimental efficiency and more visual in experimental result;
the device can be used for carrying out multiple experiments on the simulated formation oil, and accurately, quickly, efficiently and visually determining the initial point of asphaltene deposition and the limit of deposition permeability by changing the temperature, the pressure and the gas injection condition;
the device can be repeatedly used, the actual core of the oil reservoir can be simulated in the microscopic etching model to set the penetration zones with different permeabilities, and the asphaltene deposition rule in the actual core of the oil reservoir can be more accurately obtained.
Alternatively, the micro-etching model comprises ground glass and plate glass;
a liquid inlet and a liquid outlet are respectively etched from two ends of the ground glass to the middle part on the top surface of the ground glass, and a plurality of flow channels are etched between the liquid inlet and the liquid outlet in parallel;
a plurality of permeation regions are etched on the top surface of the ground glass, and each permeation region is communicated with one flow channel;
the flat glass is covered on the top surface of the ground glass.
Specifically, the plate glass and the ground glass can be fixedly connected by bonding or other methods to ensure that each penetration area is communicated with the liquid inlet and the liquid outlet;
further, the micro-etching model can be a micro-etching model of the homogeneous characteristic groove and is used for testing the initial point of the asphaltene precipitation of the homogeneous reservoir; the method can also be used as a micro-etching model of the heterogeneous characteristic groove for testing the initial point of asphaltene precipitation under the heterogeneous reservoir condition.
As an alternative scheme, each penetration zone is in a groove shape, a plurality of circular depressed grooves for simulating pores are distributed on the bottom surface of each groove, and the circular depressed grooves in the penetration zones are the same or different in size;
the outline of each permeation area is rectangular, one side of each permeation area is parallel to the extending direction of the flow channel and is overlapped with the flow channel, and the other sides of each permeation area are closed.
Specifically, the circular depressed trench for simulating the pore in each permeability zone is usually made by a photoetching method according to the pore throat sizes of reservoir cores of different permeabilities of a target reservoir, and generally has a concavo-convex shape of tens of microns to hundreds of microns;
furthermore, each permeability area is three-sided closed, and one side is communicated with the runner, and the design is more favorable for exerting the dissolving and extracting action of the injected gas and the crude oil, so that the phenomenon that the asphaltene is displaced after being deposited and formed under the gas drive action to cause that the asphaltene cannot be observed to precipitate and bring adverse effects to the experimental result is avoided.
As an alternative, the injection device comprises two injection pumps and two intermediate containers, wherein one of the injection pumps is connected with the liquid inlet of the micro-etching model through one of the intermediate containers, and a valve is arranged between the intermediate container and the liquid inlet of the micro-etching model;
another injection pump is connected to the reactor through another intermediate vessel.
In particular, the intermediate container is arranged to play a role in storage and slow flow so as to ensure the smooth operation of the experiment.
As an alternative, the back-pressure valve is connected to the back-pressure pump, and a valve is arranged between the back-pressure valve and the metering device.
Specifically, the application pressure range of the device is 0-70 Mpa, and the application temperature range is 0-300 ℃.
As an alternative scheme, the metering device comprises a gas-liquid separator and a liquid metering pipe, the inlet end of the gas-liquid separator is connected with the back pressure valve, the liquid outlet end of the gas-liquid separator is connected with the liquid metering pipe, and the gas outlet end of the gas-liquid separator is provided with a pressure gauge.
As an alternative scheme, the image acquisition device comprises a bottom lamp, a camera and an image processor, wherein the bottom lamp is arranged below the reaction kettle, and the camera is arranged above the window and connected to the image processor.
The invention also discloses an experimental method for testing asphaltene deposition, which utilizes the microscopic experimental device for testing asphaltene deposition, and the method comprises the following steps:
1) sealing the microscopic etching model in the reaction kettle;
2) vacuumizing the reaction kettle and the interior of the micro etching model by using a vacuum pump;
3) injecting a fluid medium into the micro-etching model by using an injection device, and simultaneously injecting saturated deionized water into the reaction kettle, so that the micro-etching model and the interior of the reaction kettle are boosted to be above the bubble point pressure of the crude oil of the target oil reservoir;
4) keeping the pressure constant, and heating the temperature inside the reaction kettle to the temperature of the target oil reservoir by using a temperature control system;
5) injecting saturated simulated formation crude oil into the micro etching model by using an injection device, so that the plurality of permeation regions are filled with the simulated formation crude oil;
6) and reducing the temperature inside the micro etching model and the reaction kettle and the pressure inside the micro etching model to a target temperature and a target pressure, and then displacing the simulated formation crude oil by using a displacement fluid, or directly injecting gas into the micro etching model to displace the formation crude oil, and capturing residues in the micro etching model by using an image acquisition device.
Specifically, the method is convenient to implement, and can accurately, quickly, efficiently and visually determine the temperature and pressure conditions and the deposition permeability limit of the deposition of the asphaltene as well as the temperature and pressure conditions and the deposition permeability limit of the deposition of the asphaltene in the gas flooding process.
Alternatively, step 6) comprises:
6.1) reducing the temperature inside the micro-etching model and the reaction kettle and the pressure inside the micro-etching model step by using a temperature control system and a back pressure valve to a target temperature and a target pressure, and maintaining the stability;
6.2) injecting a displacement fluid into the micro-etching model by using an injection device, and capturing the color change of crude oil in the micro-etching model by using an image acquisition device in the injection process until the color does not change any more;
6.3) if no residue exists in the micro-etching model, returning to the step 5), and changing the target temperature and the target pressure; if residues are left in the micro-etching model, capturing the residues in the micro-etching model by using an image acquisition device, wherein the current temperature and pressure are the starting point of asphaltene precipitation, and the permeability corresponding to the permeation area with the residues is the boundary of the deposition permeability at the current temperature and pressure.
Specifically, during the injection of the displacement fluid, the crude oil will gradually fade in color, and when the color is not changed, the fluid in the crude oil has been displaced, and if any, the residue is asphaltene precipitation.
Alternatively, step 6) comprises:
6.1) injecting gas into the microscopic etching model by using an injection device, wherein the gas injection pressure is gradually increased from low to high, and the color change of the crude oil in the model is continuously captured in the gas injection process;
6.2) stopping gas injection when the gas-liquid ratio of the produced fluid in the micro etching model is not less than 3000 as measured by the metering device after the color of the crude oil is not changed any more;
6.3) injecting a displacement fluid into the micro etching model by using an injection device, capturing the color change of crude oil in the model in the injection process, and stopping injecting the displacement fluid until the color and the state are not changed any more;
6.4) if no residue exists in the micro etching model, returning to the step 5), and increasing the injection pressure of the gas; if residues are left in the micro-etching model, capturing the residues in the micro-etching model by using an image acquisition device, wherein the current temperature and gas injection pressure are the starting points of asphaltene precipitation in the gas drive process, and the permeability corresponding to the permeability zone where the residues are left is the boundary of the precipitation permeability at the current temperature and gas injection pressure in the gas drive process.
Specifically, in the gas flooding process, liquid substances in the crude oil are displaced, so that the concentration of colloids and asphaltenes in the crude oil is higher and higher, the color of the crude oil is gradually darker, and when the color of the crude oil is not changed any more, the liquid substances in the crude oil are displaced; when the gas-liquid ratio of the fluid produced in the micro-etching model is more than or equal to 3000, the liquid in the micro-etching model is very little, that is, the liquid is completely displaced, namely, only residual colloid and asphaltene are removed, and at the moment, the displacement fluid is injected into the micro-etching model, so that the color of the crude oil is gradually lightened.
Example 1
FIG. 1 shows a schematic structural diagram flowchart of a microscopic experimental apparatus for testing asphaltene deposition according to the present embodiment; fig. 2 shows a schematic configuration diagram of the micro etching model of the present embodiment.
As shown in fig. 1, the microscopic experimental apparatus for testing asphaltene deposition comprises a microscopic etching model 1, wherein the microscopic etching model 1 is composed of ground glass and plate glass, a liquid inlet and a liquid outlet are respectively etched from two ends of the ground glass to the middle part on the top surface of the ground glass, three flow channels are parallelly etched between the liquid inlet and the liquid outlet, and the connecting line of the liquid inlet and the liquid outlet is the diagonal line of the ground glass; etching three permeable areas on the top surface of the ground glass, wherein each permeable area is in a groove shape, a plurality of circular depressed grooves for simulating pores are distributed on the bottom surface of each groove, the sizes of the circular depressed grooves in each permeable area are different, and the specific sizes are manufactured according to the pore throat size of a target oil reservoir in proportion; each permeation region is rectangular in outline, one side of each permeation region is parallel to the extending direction of the flow channel and is overlapped with the flow channel, and the other sides of each permeation region are closed, as shown in fig. 2; the plate glass covers the top surface of the ground glass and is bonded with the top surface of the ground glass;
the reaction kettle 2 is connected with a temperature control system 8 and a vacuum pump 7, a sapphire window 13 is arranged on a top cover of the reaction kettle 2, the micro-etching model 1 is arranged in the reaction kettle 2 and is tightly pressed by a sealing ring 14 and a bolt 15, and three penetration areas of the micro-etching model 1 face the sapphire window 13; a bottom lamp 16 is arranged below the reaction kettle 2, and a camera 9 is arranged above the sapphire window 13 and connected with an image processor 10 so as to collect images of the micro-etching model 1 through the sapphire window 13;
the injection device comprises two injection pumps 5 and two intermediate containers 6, wherein one injection pump 5 is connected with the liquid inlet of the micro-etching model 1 through one intermediate container 6 and is used for injecting fluid into the micro-etching model 1, and a valve 4 is arranged between the intermediate container 6 and the liquid inlet of the micro-etching model 1; another injection pump 5 is connected to the reaction vessel 2 through another intermediate container 6 for injecting fluid into the reaction vessel 2;
the metering device is used for measuring the gas-liquid ratio of fluid produced by the micro etching model 1 and comprises a gas-liquid separator 11 and a liquid metering measuring pipe 12, wherein the inlet end of the gas-liquid separator 11 is connected with the back pressure valve 3, the liquid outlet end of the gas-liquid separator 11 is connected with the liquid metering measuring pipe 12, and the gas outlet end of the gas-liquid separator 11 is provided with a pressure gauge;
the back-pressure valve 3 is arranged between the metering device 11 and the liquid outlet of the micro etching model 1, connected to the back-pressure pump and used for adjusting the pressure in the micro etching model 1, and a valve 4 is arranged between the back-pressure valve 3 and the metering device.
The device is high in experimental efficiency and more visual in experimental result, simulated formation oil is injected into the microscopic etching model, the temperature and the pressure in the reaction kettle and the microscopic etching model are controlled by the temperature control system and the back pressure valve, the simulated formation oil is displaced after the temperature and the pressure of the device are stable, the camera is used for capturing the color change of crude oil and whether residues are contained in the microscopic etching model or not, the initial point of asphaltene deposition is determined, and the limit of the deposition permeability of the asphaltene is determined through the permeation area of the residue deposition.
The device can be used for carrying out multiple experiments on simulated formation oil, and accurately, quickly, efficiently and visually determining the initial point of asphaltene deposition and the limit of deposition permeability by changing the temperature, the pressure and the gas injection condition.
Example 2
The embodiment discloses an experimental method for testing asphaltene deposition, which utilizes the microscopic experimental device for testing asphaltene deposition in the embodiment 1, and comprises the following steps:
1) manufacturing a micro-etching model according to a certain oil reservoir actual rock core in proportion, wherein the micro-etching model comprises three penetration zones, the penetration rates are respectively 1000md, 2000md and 3000md, the diameters of a liquid inlet, a liquid outlet and a flow passage are 0.4mm, placing the micro-etching model in a reaction kettle, tightly pressing the micro-etching model by using a sealing ring and a bolt, and sealing the micro-etching model in the reaction kettle by using a top cover with a sapphire window;
2) vacuumizing the reaction kettle and the interior of the micro-etching model by using a vacuum pump until the pressure reaches-0.1 MPa, and closing valves of a liquid inlet and a liquid outlet of the micro-etching model;
3) injecting saturated petroleum ether into the micro-etching model through an injection pump and an intermediate container, simultaneously injecting saturated deionized water into the reaction kettle through another injection pump and the intermediate container, and boosting the pressure inside the micro-etching model to be above the bubble point pressure of the target oil reservoir crude oil through a back pressure valve;
4) keeping the pressure constant, and heating the temperature inside the reaction kettle to the temperature of the target oil reservoir by using a temperature control system;
5) injecting saturated simulated formation crude oil into the micro-etching model through an injection pump and an intermediate container to ensure that the plurality of permeation regions are filled with the simulated formation crude oil;
6) reducing the temperature inside the micro-etching model and the reaction kettle to a target temperature by using a temperature control system, reducing the pressure inside the micro-etching model to 8MPa by using a back pressure valve, and maintaining the pressure stably;
7) injecting n-heptane into the micro-etching model through an injection pump and an intermediate container, and capturing the color change of the crude oil in the micro-etching model by using a camera in the injection process until the color does not change any more;
8) capturing residues in the micro-etching model by using a camera, wherein the residues in the micro-etching model are not found, which indicates that crude oil asphaltene is not deposited at the temperature and the pressure;
9) injecting saturated simulated formation crude oil into the micro etching model again, reducing the temperature of the micro etching model and the temperature inside the reaction kettle to a target temperature by using a temperature control system, reducing the pressure in the micro etching model to 6MPa by using a back pressure valve, and maintaining the stability;
10) injecting n-heptane into the micro-etching model through an injection pump and an intermediate container, and capturing the color change of the crude oil in the micro-etching model by using a camera in the injection process until the color does not change any more;
11) the residues in the micro-etching model are captured by using a camera, and the residues are found in a penetration region with the permeability of 3000md in the micro-etching model, so that the situation that the permeability of a reservoir stratum with the permeability of more than 3000md near a target oil reservoir production well is indicated, and asphaltene precipitates are easily separated out when the bottom hole pressure is reduced to 6 MPa.
Example 3
The embodiment discloses an experimental method for testing asphaltene deposition, which utilizes the microscopic experimental device for testing asphaltene deposition in the embodiment 1, and comprises the following steps:
1) manufacturing a micro-etching model according to a certain oil reservoir actual rock core in proportion, wherein the micro-etching model comprises three penetration zones, the penetration rates are respectively 300md, 500md and 1000md, the diameters of a liquid inlet, a liquid outlet and a flow passage are 0.4mm, placing the micro-etching model in a reaction kettle, tightly pressing the micro-etching model by using a sealing ring and a bolt, and sealing the micro-etching model in the reaction kettle by using a top cover with a sapphire window;
2) vacuumizing the reaction kettle and the interior of the micro-etching model by using a vacuum pump until the pressure reaches-0.1 MPa, and closing valves of a liquid inlet and a liquid outlet of the micro-etching model;
3) injecting saturated petroleum ether into the micro-etching model through an injection pump and an intermediate container, simultaneously injecting saturated deionized water into the reaction kettle through another injection pump and the intermediate container, and boosting the pressure inside the micro-etching model to be above the bubble point pressure of the target oil reservoir crude oil through a back pressure valve;
4) keeping the pressure constant, and heating the temperature inside the reaction kettle to the temperature of the target oil reservoir by using a temperature control system;
5) injecting saturated simulated formation crude oil into the micro-etching model through an injection pump and an intermediate container to ensure that the plurality of permeation regions are filled with the simulated formation crude oil;
6) injecting CO into the micro-etching model in a constant pressure mode of 10MPa through an injection pump and an intermediate container2Continuously capturing the color change of the crude oil in the model in the gas injection process;
7) stopping gas injection when the gas-liquid ratio of the produced fluid in the micro-etching model reaches 3000 measured by the metering device after the color of the crude oil is not changed any more;
8) injecting n-heptane into the micro-etching model by using an injection pump and an intermediate container, capturing the color change of crude oil in the model in the injection process, and stopping injection until the color and the state do not change any more;
9) no residue was captured in the microetch pattern, indicating that crude oil asphaltenes were not deposited at the injection pressure;
10) injecting CO into the micro-etching model in a constant pressure mode of 12.5MPa through an injection pump and an intermediate container2Continuously capturing the color change of the crude oil in the model in the gas injection process;
11) stopping gas injection when the gas-liquid ratio of the produced fluid in the micro-etching model reaches 3000 measured by the metering device after the color of the crude oil is not changed any more;
11) injecting n-heptane into the micro-etching model by using an injection pump and an intermediate container, capturing the color change of crude oil in the model in the injection process, and stopping injection until the color and the state do not change any more;
12) capturing residues in the micro-etching model by using a camera, finding that residues exist in a penetration zone with the permeability of 300md in the micro-etching model, and indicating that the target oil reservoir is injected with CO2When the pressure is more than 12.5MPa in the process, the permeability is lower than that of a reservoir stratum of 300md, and asphaltene precipitation is easy to separate out.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (10)
1. A microscopic experimental apparatus for testing asphaltene deposition, comprising:
the micro-etching model is made of transparent materials, a plurality of permeation areas are etched in the micro-etching model, a liquid inlet and a liquid outlet are respectively arranged at two ends of the micro-etching model, and the permeation areas are located on the same plane and connected between the liquid inlet and the liquid outlet in parallel;
the injection device is connected with the liquid inlet of the micro-etching model and is used for injecting fluid into the micro-etching model;
the metering device is connected to the liquid outlet of the micro etching model and is used for measuring the gas-liquid ratio of the fluid produced by the micro etching model;
the back pressure valve is arranged between the metering device and the liquid outlet of the micro etching model and is used for adjusting the pressure in the micro etching model;
the reaction kettle is connected with a temperature control system and a vacuum pump, a window is arranged on a top cover of the reaction kettle, the micro-etching model is sealed in the reaction kettle, and a plurality of permeation areas of the micro-etching model face the window;
and the image acquisition device acquires the image of the micro etching model through the window.
2. A microscopic experimental apparatus for testing asphaltene deposition according to claim 1, wherein said microscopic etching model comprises ground glass and plate glass;
the liquid inlet and the liquid outlet are respectively etched from two ends of the ground glass to the middle part on the top surface of the ground glass, and a plurality of flow channels are etched between the liquid inlet and the liquid outlet in parallel;
the plurality of permeation regions are etched on the top surface of the ground glass, and each permeation region is communicated with one flow channel;
the plate glass covers the top surface of the ground glass.
3. The microscopic experimental apparatus for testing asphaltene deposition according to claim 2, wherein each of the infiltration regions is groove-shaped, a plurality of circular concave grooves for simulating pores are distributed on the bottom surface of the groove, and the sizes of the circular concave grooves in the plurality of infiltration regions are the same or different;
the outline of each permeation area is rectangular, one side of each permeation area is parallel to the extending direction of the flow channel and is overlapped with the flow channel, and the other sides of each permeation area are closed.
4. The micro experimental apparatus for testing asphaltene deposition according to claim 1, wherein the injection apparatus comprises two injection pumps and two intermediate containers, wherein one of the injection pumps is connected to the liquid inlet of the micro etching model through one of the intermediate containers, and a valve is provided between the intermediate container and the liquid inlet of the micro etching model;
the other injection pump is connected to the reaction kettle through the other intermediate container.
5. The microscopic experimental apparatus for testing asphaltene deposition according to claim 1, wherein the back-pressure valve is connected to a back-pressure pump, and a valve is provided between the back-pressure valve and the metering device.
6. The microscopic experimental apparatus for testing asphaltene deposition according to claim 1, wherein the metering device comprises a gas-liquid separator and a liquid metering tube, the inlet end of the gas-liquid separator is connected to the back pressure valve, the liquid outlet end of the gas-liquid separator is connected to the liquid metering tube, and the gas outlet end of the gas-liquid separator is provided with a pressure gauge.
7. The microscopic experimental apparatus for testing asphaltene deposition according to claim 1, wherein the image acquisition device comprises a bottom lamp, a camera and an image processor, the bottom lamp is disposed below the reaction kettle, and the camera is disposed above the window and connected to the image processor.
8. An experimental method for testing asphaltene deposition using the microscopic experimental apparatus for testing asphaltene deposition according to any one of claims 1-7, characterized in that the method comprises the following steps:
1) sealing the micro-etching model in the reaction kettle;
2) vacuumizing the reaction kettle and the interior of the micro etching model by using the vacuum pump;
3) injecting a fluid medium into the micro-etching model by using the injection device, and injecting saturated deionized water into the reaction kettle simultaneously to increase the pressure inside the micro-etching model and the reaction kettle to be higher than the bubble point pressure of the target reservoir crude oil;
4) keeping the pressure constant, and heating the temperature inside the reaction kettle to the target oil reservoir temperature by using the temperature control system;
5) injecting saturated simulated formation crude oil into the micro-etching model by using the injection device, so that the plurality of permeation regions are filled with the simulated formation crude oil;
6) and reducing the temperature inside the micro etching model and the reaction kettle and the pressure inside the micro etching model to a target temperature and a target pressure, and then displacing the simulated formation crude oil by using a displacement fluid, or directly injecting gas into the micro etching model to displace the formation crude oil, and capturing residues in the micro etching model by using the image acquisition device.
9. The experimental method for testing asphaltene deposition according to claim 8, wherein said step 6) comprises:
6.1) reducing the temperature inside the microscopic etching model and the reaction kettle and the pressure inside the microscopic etching model step by using the temperature control system and the back pressure valve to a target temperature and a target pressure and maintaining the temperature and the pressure stable;
6.2) injecting a displacement fluid into the micro etching model by using an injection device, and capturing the color change of the crude oil in the micro etching model by using the image acquisition device in the injection process until the color does not change any more;
6.3) if no residue exists in the micro-etching model, returning to the step 5), and changing the target temperature and the target pressure; and if residues are left in the micro-etching model, capturing the residues in the micro-etching model by using the image acquisition device, wherein the current temperature and pressure are the starting point of asphaltene precipitation, and the permeability corresponding to the permeation area with the residues is the boundary of the deposition permeability at the current temperature and pressure.
10. The experimental method for testing asphaltene deposition according to claim 8, wherein said step 6) comprises:
6.1) injecting gas into the micro etching model by using the injection device, wherein the gas injection pressure is gradually increased from low to high, and the color change of crude oil in the model is continuously captured in the gas injection process;
6.2) stopping gas injection when the gas-liquid ratio of the produced fluid in the micro etching model is not less than 3000 according to the measurement result of the metering device after the color of the crude oil is not changed any more;
6.3) injecting a displacement fluid into the micro etching model by using the injection device, capturing the color change of the crude oil in the model in the injection process, and stopping injecting the displacement fluid until the color and the state are not changed any more;
6.4) if no residue exists in the micro etching model, returning to the step 5), and increasing the injection pressure of the gas; and if residues are left in the micro-etching model, capturing the residues in the micro-etching model by using the image acquisition device, wherein the current temperature and gas injection pressure are the starting points of asphaltene precipitation in the gas drive process, and the permeability corresponding to the permeability zone where the residues are left is the boundary of the precipitation permeability at the current temperature and gas injection pressure in the gas drive process.
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