System and method for extracting trace hydrocarbons in oil field water

Abstract

The invention relates to the technical field of oil-gas exploration, and discloses a system and a method for extracting trace hydrocarbons in oil field water. An extraction system for trace hydrocarbons in oil field water comprises an oscillation mixing device, the condensing device is used for cooling the oil field water and extracting solvent mixed solution heated by the oscillation mixing device; the separating and settling unit is used for receiving layering and liquid separation of mixed liquid of oil field water and an extracting solvent; and the oscillation mixing device mixes the oil field water and the extraction solvent by adopting rotary oscillation and ultrasonic oscillation. The invention relates to a method for extracting trace hydrocarbons in oil field water. The method comprises the following steps: fully mixing oil field water and an extraction solvent by adopting rotary oscillation and ultrasonic oscillation; oil field water and extracting solvent mixed liquid enters the condensing device to be cooled and then is discharged into the separating and settling unit to be layered and separated. The technical scheme is operated in a closed state, hydrocarbons in the oil field water can be effectively separated, light components of the hydrocarbons can be reserved, and the extracted dissolved hydrocarbons in the water can provide important information for formation of oil and gas reservoirs and parent material sources.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas exploration, and particularly to a system and method for extracting trace hydrocarbons in oilfield water; it is used for extracting trace hydrocarbons in oilfield water and can further achieve cyclic extraction. Background Art

[0002] Oilfield water refers to the formation water associated with oil and gas in the reservoir, and it is an important component of reservoir fluids. Formation water participates in the whole process of oil and gas formation, so the chemical composition of oilfield water is closely related to the formation of oil and gas reservoirs; its hydrocarbon components and composition can directly or indirectly reflect some characteristics of crude oil and natural gas in the oil and gas reservoirs. Therefore, studying the dissolved hydrocarbons in oilfield water can obtain the source information of crude oil and natural gas. In order to obtain the geochemical composition information of hydrocarbons in oilfield water, it is necessary to first separate the hydrocarbons from the oilfield water.

[0003] At present, in the laboratory, the liquid-liquid extraction method is generally used to separate the hydrocarbons in oilfield water. According to the properties of oilfield water and the different required components, the extraction solvents are generally chloroform, dichloromethane, petroleum ether, etc. The separation method is generally that after the experimenter adds the extraction solvent into the bottle, tightens the bottle cap and manually shakes it to make it fully mixed, then transfers the liquid to a separating funnel for sedimentation and stratification, and finally obtains the hydrocarbon components dissolved in the extraction solvent. However, this relatively primitive method belongs to the form of manual shaking, which has the disadvantages of consuming a lot of manpower and time, insufficient extraction, easy leakage of reagents, harming the health of experimenters, etc. Moreover, the experimental result data has low repeatability and large errors, which is not conducive to the development of subsequent test research work and cannot accurately obtain the source information of hydrocarbons in oilfield water.

[0004] Through retrieval, some patent documents related to oil-water separation devices are obtained. When designing their technologies, they do not consider the characteristics of hydrocarbons in oilfield water and have some disadvantages.

[0005] An extraction device for oil in water (CN212998517U), which relates to the technical field of oil-water separation, includes a negative pressure generating device and at least one extraction unit. The extraction unit includes a negative pressure oscillation bottle, a liquid storage bottle and a negative pressure joint. Both the top and bottom of the negative pressure oscillation bottle are open. At least one thin tube is fixedly arranged at the bottom of the negative pressure oscillation bottle, and the thin tube extends into the bottom of the liquid storage bottle. A vacuum breaking port for introducing air is arranged at the top of the liquid storage bottle. A negative pressure joint is arranged at the top of the negative pressure oscillation bottle. One end of the negative pressure joint extends into the negative pressure oscillation bottle and can seal the top of the negative pressure oscillation bottle, and the other end is connected to the negative pressure generating device. The negative pressure generating device can make the negative pressure oscillation bottle generate negative pressure. The mixed liquid splashes and oscillates under the action of pressure, and the extraction process only needs to be manually controlled to start and stop the device.

[0006] An oil-in-water enrichment extraction device (CN112206550A), mainly related to the field of extraction technology. It includes a turntable and a liquid transfer path; a transmission mechanism for controlling the rotation of the turntable is arranged at the bottom of the table, and a plurality of water sample bottle bodies are arranged in an annular array on the top of the turntable; the liquid transfer path includes an extraction liquid placement bottle, a multi-way switching valve, a waste liquid bottle, a water filtration device, a magnesium silicate device, a measurement colorimetric cell, and a first air pump. The beneficial effects of the present invention are as follows: It can continuously extract and measure multiple water sample samples; moreover, when using this extraction and measurement device, the entire operation process is fully automated, without the need to touch any liquid by hand, and the measurement experiment process is safer. The waste liquid is discharged by means of negative pressure transfer through an air pump. And the pipeline can be cleaned based on the principle of negative pressure transfer.

[0007] An oscillating extractor with an automatic constant volume liquid adding device (CN205095456U), which relates to the field of chemical devices. It includes a separating funnel, and the separating funnel is connected to at least one liquid inlet. The liquid inlet is connected to the automatic constant volume liquid adding device. By setting a peristaltic pump, a motor, a one-way solenoid valve, and a control system, the digital operation of constant volume liquid adding is realized, and the error caused by manual operation is avoided.

[0008] Through research and analysis, although the above-mentioned patent documents solve some problems of pure manual extraction to a certain extent, there are still deficiencies in the separation of hydrocarbons in oilfield water: the hydrocarbons in oilfield water are trace or even measured, and the characteristic of extremely low content of the target product should be considered during separation and extraction. Moreover, most of the hydrocarbons dissolved in water are lighter oils with fewer carbon atoms, which are volatile at high temperatures. As the solution temperature rises, some components will escape. Summary of the Invention

[0009] The present application provides an extraction system and method for trace hydrocarbons in oilfield water to solve the above-mentioned technical problems of poor extraction effect and low efficiency of trace hydrocarbons in oilfield water in the prior art.

[0010] According to one aspect of the present application, an embodiment provides an extraction system for trace hydrocarbons in oilfield water, including:

[0011] An oscillating mixing device for oilfield water extraction;

[0012] A condensation device connected to the outlet of the oscillating mixing device through a pipeline; the condensation device is used to cool the mixed liquid of oilfield water and extraction solvent heated by the oscillating mixing device; and

[0013] A separation and sedimentation unit connected to the inlet of the oscillating mixing device; the separation and sedimentation unit is used to receive the layering and liquid separation of the cooled mixed liquid of oilfield water and extraction solvent;

[0014] Among them, the oscillation mixing device uses rotational oscillation and ultrasonic oscillation to mix the oilfield water and the extraction solvent.

[0015] In one embodiment, the oscillation mixing device includes an extraction solvent storage tank and an ultrasonic spiral tube connected to the outlet of the extraction solvent storage tank; a rotator for driving the ultrasonic spiral tube to rotate itself is provided on the ultrasonic spiral tube, and valves are provided at both ends of the ultrasonic spiral tube; the oscillation mixing device further includes an ultrasonic oscillation water tank and an ultrasonic generator.

[0016] In one embodiment, the condensation device includes a condensation spiral tube connected to the outlet of the oscillation mixing device; the condensation device further includes a condensation water tank cooperating with the condensation spiral tube.

[0017] In one embodiment, a circulation device is further included; the circulation device is connected to the outlet of the condensation device; the circulation device is used to pass the oilfield water and extraction solvent mixture discharged from the condensation device into the oscillation mixing device.

[0018] In one embodiment, the circulation device includes a circulation pipeline connected to the outlet of the condensation device; a circulation pump is provided on the circulation pipeline.

[0019] In one embodiment, the separation and sedimentation unit includes a liquid separation tank and an outlet pipeline connected to the bottom of the liquid separation tank; the outlet pipeline includes an extraction product outlet valve and an oilfield water outlet valve provided on the outlet pipeline; the oilfield water outlet valve is connected to the oscillation mixing device.

[0020] In one embodiment, the extraction system for trace hydrocarbons in oilfield water further includes a pressure balancing device; the pressure balancing device includes a communicating vessel connected to the pipeline; the communicating vessel maintains the pressure balance in the extraction system for trace hydrocarbons in oilfield water through a water seal.

[0021] According to one aspect of the present application, one embodiment provides a method for extracting trace hydrocarbons in oilfield water based on the extraction system for trace hydrocarbons in oilfield water as described in any one of the above, including the following steps:

[0022] S1. Add oilfield water and extraction solvent to the oscillation mixing device, and fully mix them into a mixture by using rotational oscillation and ultrasonic oscillation;

[0023] S2. The oilfield water and extraction solvent mixture enters the condensation device to be cooled and then is discharged into the separation and sedimentation unit for stratification and liquid separation.

[0024] In one embodiment, the method for extracting trace hydrocarbons in oilfield water further includes the following steps:

[0025] S3. The oilfield water separated by the separation and sedimentation unit is discharged to the oscillation mixing device for re-extraction to form a cyclic extraction of the oilfield water.

[0026] In one embodiment, in step S1, the total volume of the extraction solvent and the oilfield water is less than half of the volume of the oscillating spiral tube of the oscillating mixing device.

[0027] The technical solution of the above embodiment operates in a closed state. The oilfield water sample and the extraction solvent are successively added into the oscillating mixing device, and self-rotation stirring and ultrasonic oscillation are carried out to make them fully mixed, and then cooled to room temperature in the condensing device; thereafter, the mixed liquid is transported to the separation and sedimentation unit for stratification, and the extraction solvent part is discharged through the discharge port. The hydrocarbons in the oilfield water can be effectively separated and the light component composition can be retained. The dissolved hydrocarbons in the extracted water can provide important information for the formation of oil and gas reservoirs and the source of the parent material. This technical solution can reduce the use of extraction solvents and the emission of toxic hydrocarbons.

[0028] In the above, the remaining part of the oilfield water can also be discharged through the discharge port, and it is continuously passed into the oscillating mixing device and the extraction solvent is added again, and then oscillated and stirred again; the extraction treatment is continued. And it can be circulated according to the type of oilfield water and the requirements of the experiment, and the cycle extraction is carried out until the experiment is completed. The separation of trace hydrocarbons in the oilfield water can be maximally realized.

[0029] Furthermore, in the extraction system for trace hydrocarbons in oilfield water, by connecting an electronic valve, a photoelectric inductor, an ultrasonic generator, etc. through a central controller, the cyclic repeated extraction of oilfield water can be carried out, and the separation of trace hydrocarbons in oilfield water can be realized. Through the precise control of the extraction solvent addition valve, the extraction solvent can be added in small amounts and multiple times, reducing the use of the solvent; and when the system operates, the oilfield water sample in its circulation system does not contact with air, which is a sealed cycle, reducing the release of toxic hydrocarbons and meeting the requirements of green and environmental protection. Description of the Drawings

[0030] Figure 1 is a schematic structural diagram of an extraction system for trace hydrocarbons in oilfield water in an embodiment of the present application;

[0031] Figure 2 is a schematic diagram of the separation of group components and chromatographic and mass spectrometric tests of the extraction product of a sample in an embodiment of the present application;

[0032] Reference Signs:

[0033] 101 - Liquid separation tank; 102 - Photoelectric inductor; 103 - Extraction product outlet valve; 104 - Oilfield water outlet valve; 105 - Extraction product discharge port; 201 - Extraction solvent storage tank; 202 - Extraction solvent addition valve; 203 - Ultrasonic generator; 204 - Valve before ultrasonic spiral tube; 205 - Rotator; 206 - Ultrasonic oscillation water tank; 207 - Ultrasonic spiral tube; 208 - Valve after ultrasonic spiral tube; 301 - Condensation water tank; 302 - Condensation spiral tube; 402 - Connection line; 401 - Central controller; 501 - Pump equipment; 502 - Circulation pipeline; 503 - Communicator. Detailed implementation manners

[0034] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0035] In order to enable those skilled in the art of the present technology to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present application.

[0036] It should be noted that the terms "first", "second", etc. in the present application are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances, so as to implement the embodiments of the present application described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0037] It should be understood that when an element (such as a layer, film, region, or substrate) is described as being "on" another element, the element can be directly on the other element, or there may also be an intermediate element. Moreover, in the present application, when it is described that an element is "connected" to another element, the element can be "directly connected" to the other element, or "connected" to the other element through a third element.

[0038] Embodiment 1

[0039] Please refer to Figure 1, an embodiment of the present application provides a micro hydrocarbon extraction system for oilfield water, comprising: a shaking and mixing device, a condensation device connected to the outlet of the shaking and mixing device through a pipeline, and a separation and sedimentation unit connected to the inlet of the shaking and mixing device; wherein, the shaking and mixing device is used for shaking and mixing oilfield water for extraction; the condensation device is used for cooling the mixture of oilfield water and extraction solvent heated by the shaking and mixing device; the separation and sedimentation unit is used for receiving the stratification and liquid separation of the cooled mixture of oilfield water and extraction solvent. Preferably, the shaking and mixing device uses rotary shaking and ultrasonic shaking to mix oilfield water and extraction solvent.

[0040] In one embodiment, the oscillating mixing device includes an extraction solvent storage tank 201 and an ultrasonic spiral tube 207 connected to the outlet of the extraction solvent storage tank 201; a rotator 205 for driving the ultrasonic spiral tube 207 to rotate about its own axis is provided on the ultrasonic spiral tube 207, and valves are provided at both ends of the ultrasonic spiral tube 207; among them, the valve at the front end of the ultrasonic spiral tube 207 is set as the front valve 204 of the ultrasonic spiral tube; correspondingly, the valve at the rear end of the ultrasonic spiral tube 207 is set as the rear valve 208 of the ultrasonic spiral tube. Preferably, the oscillating mixing device further includes an ultrasonic oscillating water tank 206 and an ultrasonic generator 203. Specifically, the oscillating mixing system includes an extraction solvent storage tank 201, an extraction solvent addition valve 202, an ultrasonic generator 203, a front valve 204 of the ultrasonic spiral tube, a rotator 205, an ultrasonic oscillating water tank 206, an ultrasonic spiral tube 207, and a rear valve 208 of the ultrasonic spiral tube. Preferably, the extraction solvent storage tank 201 is detachable and is connected to the extraction solvent addition valve 202 by a threaded port. When the extraction solvent storage tank 201 is removed, the oilfield water sample and the extraction reagent can also be directly added into the oscillating mixing device through the extraction solvent addition valve 202. Preferably, the ultrasonic generator 203 is located on the outer wall of the ultrasonic oscillating water tank 206 and is connected to the central controller 401 through a connection line 402. Among them, the front valve 204 of the ultrasonic spiral tube is connected to the rotator 205 and is used to discharge the oilfield water and the extraction solvent into the ultrasonic spiral tube 207. The rotator 205 is connected to the ultrasonic spiral tube 207 and is connected to the central controller 401 through a connection line 402, and is used to make the ultrasonic spiral tube 2 of the ultrasonic spiral tube 207 rotate around its central axis, so that the mixed liquid of the oilfield water and the extraction solvent is in full contact. Among them, the rotator 205 is a mechanical device that can make the subsequent connected ultrasonic spiral tube 207 rotate around the axis; the rotator 205 needs to be powered on and run, and its structure can have two types. The first type is a mechanical motor that can rotate in the same direction, and the second type is a rack that moves left and right, which can refer to the automatic barbecue rotation. Specifically, the rotator 205 is connected to the front valve 204 of the ultrasonic spiral tube, and the front valve 204 of the ultrasonic spiral tube is connected to the ultrasonic spiral tube 207. Through the rotator 205, the front valve 204 of the ultrasonic spiral tube can be made to rotate around the axis, and then drive the ultrasonic spiral tube 207 to rotate around the axis, while the structure of the rear valve 208 of the ultrasonic spiral tube allows the ultrasonic spiral tube 207 to rotate around the axis and the end connected to the condensation spiral tube 302 of the rear valve 208 of the ultrasonic spiral tube does not rotate. Further, the ultrasonic spiral tube 207 is located in the ultrasonic oscillating water tank 206; during operation, a part of the ultrasonic spiral tube 207 should be immersed in water.

[0041] Preferably, the extraction solvent addition valve 202, the front valve 204 of the ultrasonic spiral tube, and the rear valve 208 of the ultrasonic spiral tube are all electronic valves and are connected to the central controller 401 through a connection line 402.

[0042] In a certain solution, the post-valve 208 of the ultrasonic spiral tube is connected to a condensation device, which is used to discharge the mixed liquid of oilfield water and extraction solvent that has undergone rotational ultrasonic oscillation into the condensation device for cooling. Further, a condensation device is provided. The condensation device includes a condensation spiral tube 302 connected to the outlet of the oscillation mixing device; the condensation device also includes a condensation water tank 301 that cooperates with the condensation spiral tube 302. Preferably, the condensation water tank 301 can be connected to an external water source to cool the mixed liquid of oilfield water and extraction solvent that has been heated due to ultrasonic energy. Further, the condensation spiral tube 302 is connected to a circulation device.

[0043] In an embodiment, the trace hydrocarbon extraction system in oilfield water further includes a circulation device; the circulation device is connected to the outlet of the condensation device; the circulation device is used to introduce the mixed liquid of oilfield water and extraction solvent discharged from the condensation device into the oscillation mixing device. Preferably, the circulation device includes a circulation pipeline 502 connected to the outlet of the condensation device; a circulation pump is provided on the circulation pipeline 502. Further, the pump device 501 is located on the circulation pipeline 502, at the outlet of the condensation spiral tube 302, and is used to pump the mixed liquid of oilfield water and extraction solvent into the separation tank 101 for layering and liquid separation. After the mixed liquid is separated, the remaining oilfield water will enter the oscillation mixing device again for mixing and extraction.

[0044] Preferably, the circulation device further includes a communicating vessel 503. At this time, the communicating vessel 503 belongs to the circulation device. Of course, the communicating vessel 503 can also be used alone as a pressure balancing device. Further, the pressure balancing device includes the communicating vessel 503 connected to the pipeline; the communicating vessel 503 maintains the pressure balance in the trace hydrocarbon extraction system in oilfield water through a water seal. Specifically, the communicating vessel 503 is of a U-shaped structure, and there is a water level buffer ball at each top of the two sides. The communicating vessel 503 is located at the highest point of the trace hydrocarbon extraction system in oilfield water, one side is connected to the circulation pipeline 502, and the other side communicates with the outside air; it contains a section of water inside to maintain the pressure balance in the trace hydrocarbon extraction system in oilfield water.

[0045] One feasible solution is that the separation and sedimentation unit includes a liquid separation tank 101 and an outlet pipeline connected to the bottom of the liquid separation tank 101; the outlet pipeline includes an extraction product outlet valve 103 and an oilfield water outlet valve 104 provided on the outlet pipeline; the oilfield water outlet valve 104 is connected to the oscillation mixing device. Specifically, the liquid separation tank 101 is designed such that the upper half is in a smooth water droplet shape, and the lower half is a slender neck section with a T-shaped bifurcation structure. Preferably, the liquid separation tank 101 is made of glass, the slender neck section is externally connected with a photoelectric sensor 102, the T-shaped bifurcation port is side-connected with the extraction product outlet valve 103, and the bottom is connected with the oilfield water outlet valve 104. Further, the extraction product outlet valve 103 is connected to the extraction product discharge port 105. Among them, the liquid separation tank 101 is used for the stratification and liquid separation of the mixed liquid. The photoelectric sensor 102 should be located above the T-shaped bifurcation of the neck section and is used to detect the liquid level of the oilfield water and the extraction solvent, and is connected to the central controller 401 through the connection line 402. At the same time, the oilfield water outlet valve 104 is set to be connected to the oscillation mixing device, and is used to discharge the remaining oilfield water to the oscillation mixing device for re-extraction treatment. Preferably, both the extraction product outlet valve 103 and the oilfield water outlet valve 104 are electronic valves and are connected to the central controller 401 through the connection line 402.

[0046] In one embodiment, the above technical solution further relates to a control device. The control device includes a central controller 401 and a connection line 402. It can be understood that the connection line 402 is a connecting component between all electronic components and the central controller 401, and is used to control the operation of the entire system through the central controller 401.

[0047] Since most of the hydrocarbons dissolved in water are relatively light oils with fewer carbon atoms and are volatile at high temperatures, and ultrasonic oscillation will cause the temperature of the solution to rise, resulting in the escape of some components. If the device is not sealed and is in communication with the atmosphere, it will also cause the loss of these components and will cause environmental pollution. Therefore, in the above technical solution, the separation and sedimentation device, the oscillation mixing device, the condensation device, and the circulation device are connected in series through pipelines to form a micro-hydrocarbon extraction system in oilfield water, and this system operates under the control of a control device in a closed environment; the escape of hydrocarbon components is prevented.

[0048] The above-mentioned system for extracting trace hydrocarbons from oilfield water can realize the extraction of trace hydrocarbons from oilfield water. First, the oilfield water sample and the extraction solvent are added to the ultrasonic spiral tube 207 in sequence through the feeding port (the extraction solvent adding valve 202), and the mixture is subjected to spin stirring and ultrasonic oscillation in the oscillation tank to be re-divided and mixed; thereafter, the mixture is cooled to room temperature in the condensation tank and pumped to the sedimentation tank (liquid separation tank 101) for stratification. The extraction solvent portion is discharged through the discharge port, and the remaining portion continues to enter the ultrasonic spiral tube 207 and is added with the extraction solvent for further oscillation and stirring. A cycle program can be set through the central control device (control device) according to the type of oilfield water and the requirements of the experiment, and the extraction is circulated until the experiment is completed. The system can separate the hydrocarbons in the oilfield water to the maximum extent and retain its light component composition. The extracted dissolved hydrocarbons in the water can provide important information for the formation of oil and gas reservoirs and the source of parent materials.

[0049] Example 2

[0050] Please refer to Figure 1 An embodiment of the present application provides a method for extracting trace hydrocarbons from oilfield water, which is based on the system for extracting trace hydrocarbons from oilfield water in Example 1.

[0051] Step 1: Add sample and start the instrument;

[0052] Add sufficient water to the ultrasonic oscillation water tank 206 and the condensation water tank 301. Open the central controller 401, select the type of extraction solvent, and set parameters such as the extraction solvent addition amount, ultrasonic oscillation duration, rotation rate, and number of cycles. Open the ultrasonic spiral tube front valve 204, remove the extraction solvent storage tank 201, and inject the oilfield water sample into the ultrasonic spiral tube 207 through the extraction solvent addition valve 202. Install the extraction solvent storage tank 201 and start the system.

[0053] Step 2: fully mixing the oilfield water and the extraction solvent;

[0054] A certain amount of extraction solvent is added through extraction solvent addition valve 202 according to the set parameters. The total volume of the added extraction solvent and oilfield water sample should be less than half the volume of the oscillating spiral tube. After the addition is complete, the ultrasonic spiral tube front valve 204 and ultrasonic spiral tube rear valve 208 are closed; the ultrasonic generator 203 and rotator 205 begin operation. At this point, the mixture of oilfield water and extraction solvent in the ultrasonic spiral tube 207 undergoes simultaneous rotational oscillation and ultrasonic oscillation for thorough mixing. During this process, the pressure within the device is positive, and the water seal inside the communicating vessel 503 is high on the outside and low on the inside.

[0055] Step 3, condensing the mixture of oilfield water and extraction solvent;

[0056] After the oscillation program ends, the ultrasonic generator 203 and the rotator 205 are turned off. Due to the energy of the ultrasonic waves, the temperature of the mixture of oilfield water and extraction solvent will increase. Open the front valve 204 and the rear valve 208 of the ultrasonic spiral tube, and the mixture of oilfield water and extraction solvent enters the condensation spiral tube 302 and is cooled to room temperature.

[0057] Step 4: Separation of the mixture of oilfield water and extraction solvent; Open the pump device 501 to pump the mixture into the liquid separation tank 101 and let it stand for layering.

[0058] (1) The density of the added extraction solvent is greater than that of water;

[0059] Open the extraction product outlet valve 103 to collect the extraction product. During this process, the pressure in the system returns to normal pressure, and the water seals inside and outside the communicating vessel 503 are at the same height. When the photoelectric reactor detects the liquid level between the oilfield water and the extraction solvent, the extraction product outlet valve 103 is closed. The oilfield water outlet valve 104 is opened, and the oilfield water is injected into the ultrasonic spiral tube 207, and step 2 is repeated until the circulation program ends. After collecting the extraction product at the extraction product outlet valve 103, replace the waste liquid cup to empty the entire system.

[0060] (2) The density of the added extraction solvent is less than that of water;

[0061] Open the oilfield water outlet valve 104, and the oilfield water is injected into the ultrasonic spiral tube 207. When the photoelectric reactor detects the liquid level between the oilfield water and the extraction solvent, the oilfield water outlet valve 104 is closed, and the extraction product outlet valve 103 is opened to collect the extraction product. During this process, the pressure in the system returns to normal pressure, and the water seals inside and outside the communicating vessel 503 are at the same height. Repeat step 2 until the circulation program ends, and replace the waste liquid cup at the extraction product outlet valve 103 to empty the entire system.

[0062] Example 3

[0063] Please refer to Figure 1 , an embodiment of the present application provides a method for extracting trace hydrocarbons in oilfield water, and this method is based on the trace hydrocarbon extraction system in Example 1.

[0064] This method specifically includes the following steps:

[0065] S1. Add oilfield water and extraction solvent to the oscillation mixing device, and use rotary oscillation and ultrasonic oscillation to fully mix them into a mixture;

[0066] S2. The mixture of oilfield water and extraction solvent enters the condensation device to be cooled and then is discharged into the separation and sedimentation unit for layering and liquid separation.

[0067] Since a single extraction cannot completely separate the hydrocarbons in the oilfield water, multiple cyclic extractions are required to achieve a complete separation effect. For the above purpose, in one embodiment, the method for extracting trace hydrocarbons in oilfield water further includes the following steps: S3. The oilfield water separated by the separation and sedimentation unit is discharged to the oscillating mixing device for re-extraction to form a cyclic extraction of the oilfield water.

[0068] Among them, in order to improve the mixing effect of the oilfield water sample and the extraction solvent, in step S1, the total volume of the extraction solvent and the oilfield water is less than half of the volume of the oscillating spiral tube of the oscillating mixing device.

[0069] Embodiment 4

[0070] Please refer to Figure 2 , and the following further elaborates on the system and method for extracting trace hydrocarbons in oilfield water from the perspective of actual use.

[0071] An oil-water mixed sample is processed by the system and extraction method for extracting trace hydrocarbons in oilfield water in the above embodiments. After the sample is extracted with n-hexane, dichloromethane, and chloroform respectively, the extraction products are subjected to group component separation and chromatographic and mass spectrometric tests, and the results are shown in Figure 2 . After extraction, the original emulsified oil-water mixed liquid can obtain clearer biological marker compound information, and chloroform and dichloromethane have the best effects.

[0072] The above are only the preferred embodiments of the present application and are not intended to limit the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A micro hydrocarbon extraction system for oilfield water, characterized in that Comprising: An oscillating mixing device for oilfield water extraction; A condensation device connected to the outlet of the oscillating mixing device through a pipeline; the condensation device is used to cool the mixed liquid of oilfield water and extraction solvent heated up by the oscillating mixing device; and A separation and sedimentation unit connected to the inlet of the oscillating mixing device; the separation and sedimentation unit is used to receive the layering and liquid separation of the cooled mixed liquid of oilfield water and extraction solvent; Wherein, the oscillating mixing device mixes oilfield water and extraction solvent by rotary oscillation and ultrasonic oscillation.

2. The micro hydrocarbon extraction system from oilfield water according to claim 1, characterized in that The oscillating mixing device includes an extraction solvent storage tank and an ultrasonic spiral tube connected to the outlet of the extraction solvent storage tank; a rotator for driving the ultrasonic spiral tube to rotate is arranged on the ultrasonic spiral tube, and valves are arranged at both ends of the ultrasonic spiral tube; the oscillating mixing device further includes an ultrasonic oscillation water tank and an ultrasonic generator.

3. The micro hydrocarbon extraction system in oilfield water according to claim 1, characterized in that, The condensation device includes a condensation spiral tube connected to the outlet of the oscillating mixing device; the condensation device further includes a condensation water tank cooperating with the condensation spiral tube.

4. The trace hydrocarbon extraction system in oilfield water according to claim 1, characterized in that It further includes a circulation device; the circulation device is connected to the outlet of the condensation device; the circulation device is used to introduce the mixed liquid of oilfield water and extraction solvent discharged from the condensation device into the oscillating mixing device.

5. The trace hydrocarbon extraction system in oilfield water according to claim 4, characterized in that The circulation device includes a circulation pipeline connected to the outlet of the condensation device; a circulation pump is arranged on the circulation pipeline.

6. The micro-hydrocarbon extraction system for oilfield water according to claim 1, characterized in that, The separation and sedimentation unit includes a liquid separation tank and an outlet pipeline connected to the bottom of the liquid separation tank; the outlet pipeline includes an extraction product outlet valve and an oilfield water outlet valve arranged on the outlet pipeline; the oilfield water outlet valve is connected to the oscillating mixing device.

7. An extraction system for trace hydrocarbons in oilfield water according to any one of claims 1-6, characterized in that, It further includes a pressure balancing device; the pressure balancing device includes a communicating vessel connected to the pipeline; the communicating vessel maintains the pressure balance in the trace hydrocarbon extraction system of oilfield water through a water seal.

8. A method for extracting trace hydrocarbons in oilfield water based on the trace hydrocarbon extraction system in oilfield water described in any one of claims 1-7, characterized in that, Including the following steps: S1. Add oilfield water and extraction solvent to the oscillating mixing device, and fully mix them into a mixed liquid by rotary oscillation and ultrasonic oscillation; S2. The mixed liquid of oilfield water and extraction solvent enters the condensation device for cooling and then is discharged into the separation and sedimentation unit for layering and liquid separation.

9. A method for extracting trace hydrocarbons in oilfield water according to claim 8, characterized in that, It further includes the following steps: S3. The oilfield water separated by the separation and sedimentation unit is discharged to the oscillating mixing device for re-extraction to form a cyclic extraction of oilfield water.

10. A method for extracting trace hydrocarbons in oilfield water according to claim 8 or 9, characterized in that, In step S1, the total volume of the extraction solvent and the oilfield water is less than half of the volume of the oscillation spiral tube of the oscillating mixing device.

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