Downhole oil-water separation device and method based on composite technology

Abstract

The invention relates to the field of underwater oil extraction tools, in particular to an underground oil-water separation device and method based on a composite technology, and the underground oil-water separation device comprises a liquid extraction part which is used for obtaining a petroleum stock solution; the separation part comprises a first separation assembly and a second separation assembly and is used for enriching the petroleum stock solution to obtain water-rich liquid and oil-rich liquid; the reinjection part is used for reinjecting the water-rich liquid; the liquid separation part comprises a Y-shaped connector and a liquid separation pipe so as to converge and jack oil-rich liquid to the earth surface, a sand suction pipe is arranged on the outer side of the spiral channel, the open position of one side of the sand suction pipe is attached to a pipeline hole in the electrode pipe body, in the petroleum swirling process of the swirler, gravel enters the sand suction pipe to be automatically separated due to centrifugal force, and the oil-rich liquid can be automatically separated. According to the oil-water separation device, gravel in the oil stock solution is effectively collected and is prevented from being accumulated in the separation device and rubbing the inner wall, so that the abrasion degree of the inner wall of the underground oil-water separation device is remarkably reduced, the service life of the device is prolonged, the problem of rotational flow failure or leakage is effectively avoided, and the underwater oil extraction efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of underwater oil production tools, and particularly to a downhole oil-water separation device and a separation method based on composite technology. Background Art

[0002] Currently, with the continuous exploitation of oil resources globally, offshore oil fields have inevitably entered the high water cut stage. At this stage, the ratio of oil and water production shows an increasingly unbalanced trend. The oil production volume is decreasing day by day, while the water production volume is rising sharply, and the ratio gap between the two is constantly widening. A large amount of water produced along with the oil brings a great load to all aspects of the oil production process, seriously affecting the stability and continuity of oil production.

[0003] Therefore, how to increase the proportion of oil in the process of downhole oil production and reasonably solve the accompanying large amount of water is the top priority for ensuring the normal operation of the downhole oil-water separation device based on composite technology. For example, a downhole oil-water separation device and an oil-water separation method are disclosed in the prior art, including a central pipe. A turbine generator is arranged in the opening at the upper end of the externally connected central pipe. A pulse generator is fixed on the central pipe below the generator. The power output end of the turbine generator is connected to the power input end of the pulse generator. A multi-cup equal-flow type oil-water separator is formed on the central pipe below the pulse generator. The multi-cup equal-flow type oil-water separator includes several settling cups. Each settling cup has a positive electrode and a negative electrode directly surrounding the edge of the settling cup at the upper and lower edges respectively. All the positive electrodes in the settling cups are connected together by wires, and all the negative electrodes in the settling cups are connected together by wires. The device can improve the separation speed of oil and water, accelerate the demulsification degree and the aggregation of oil, and improve the oil-water separation ratio.

[0004] However, in the technical solution of the above downhole oil-water separation device, it is impossible to solve the accumulation and friction of the medium sand carried in the process of oil production in the downhole oil-water separation device, resulting in serious wear of the inner wall of the separation device, leading to the invalidation or leakage of the cyclone. At the same time, the accumulated sand will block the suction of the formation reinjection water, resulting in poor water absorption capacity. Summary of the Invention

[0005] The purpose of the present invention is to provide a downhole oil-water separation device and a separation method based on composite technology to solve the problems in the related technology that the accumulation and friction of the medium sand carried in the process of oil production in the downhole oil-water separation device cannot be solved, resulting in serious wear of the inner wall of the separation device, leading to the invalidation or leakage of the cyclone, and at the same time, the accumulated sand will block the suction of the formation reinjection water, resulting in poor water absorption capacity of the formation, and thus the water in the separation device cannot be discharged in time.

[0006] To this end, the present invention provides a downhole oil-water separation device based on a composite technology, comprising: A liquid extraction part for obtaining crude oil. A separation part connected to the liquid extraction part, comprising a first separation component and a second separation component, for enriching the crude oil to obtain a water-rich liquid and an oil-rich liquid. An injection part connected to the separation part for injecting the water-rich liquid back. A liquid separation part connected to the separation part and the injection part, comprising a Y-shaped joint and a liquid separation pipe, for converging and lifting the oil-rich liquid to the ground surface.

[0007] The first separation component in the separation part comprises: The first separation component is composed of an electrode tube body, a spiral channel, a pipe hole and an insulating end. Among them, the pipe holes are arranged on the electrode tube body at equal intervals. The insulating end is arranged at one end of the electrode tube body. The spiral channel is arranged in the electrode tube body in a spiral channel form.

[0008] The second separation component in the separation part comprises: The second separation component comprises a main swirl generator, a secondary swirl generator, a secondary liquid separation pipe and a secondary water separation port. Among them, the main swirl generator is arranged inside and above the main liquid separation channel, the secondary swirl generator is arranged inside and below the secondary liquid separation channel, and the main liquid separation channel is connected to the secondary liquid separation channel. The secondary liquid separation pipe is arranged inside the secondary liquid separation channel and above the secondary swirl generator. The secondary water separation port is arranged below the secondary liquid separation pipe and on the side far from the main swirl generator.

[0009] A sand suction pipe is tightly attached to the outside of the spiral channel. Among them, a pressure sensor is arranged at the bottom of the sand suction pipe.

[0010] The sand suction pipe has a structure with a closed bottom, an open upper end and an open side. The open side of the sand suction pipe is fitted with the pipe hole arranged on the electrode tube body to collect the sand and gravel in the crude oil screened out by the pipe hole.

[0011] The injection part comprises an injection three-way upper joint, an injection three-way lower joint, an injection three-way Venturi section and a secondary water separation port docking interface. Among them, the injection three-way upper joint is connected to the injection three-way lower joint through the injection three-way Venturi section. The sub-water diversion port interface is arranged in the middle of the Venturi section of the reinjection tee, and is connected to the sub-water diversion port so that the rich water liquid is reinjected into the reinjection part.

[0012] The Y-shaped joint is composed of a liquid inlet channel, a rich oil channel, and a rich water channel; Among them, the liquid inlet channel and the rich oil channel have the same diameter, and the rich oil channel is arranged above the liquid inlet channel; The rich water channel is arranged at the branch end of the Y-shaped joint, and the liquid separation pipe is arranged between the rich oil channel and the rich water channel.

[0013] On the other hand, the present invention provides a downhole oil-water separation method based on a composite technology, which is applied to the downhole oil-water separation device based on the composite technology in any of the above solutions, including: Obtain the original petroleum liquid; The original petroleum liquid is enriched by the separation part to obtain rich water liquid and rich oil liquid; The rich oil liquid enters the liquid separation part to converge and rise to the surface; The rich water liquid enters the reinjection part to be reinjected into the formation.

[0014] Respectively obtain the total flow rate of the original petroleum liquid, the rich water flow rate of the rich water liquid reinjected into the formation, and the rich oil flow rate of the rich oil liquid rising to the surface.

[0015] Determine the swirling parameters of the separation part according to the total flow rate, the rich oil flow rate, and the rich water flow rate.

[0016] The beneficial effects of the present invention are: The present invention provides a downhole oil-water separation device based on a composite technology. By arranging a sand suction pipe outside the spiral channel, and the open side of the sand suction pipe is attached to the pipe hole on the electrode tube body. During the swirling of the petroleum by the swirler, the sand and gravel enter the sand suction pipe due to centrifugal force and are automatically separated, effectively collecting the sand and gravel in the original petroleum liquid, avoiding the accumulation of sand and gravel in the separation device and rubbing against the inner wall, thereby significantly reducing the wear degree of the inner wall of the downhole oil-water separation device, extending the service life of the equipment, effectively avoiding the problems of swirl failure or leakage, and further improving the underwater oil production efficiency.

[0017] Furthermore, the separated sand and gravel are discharged in time through the sand suction pipe, preventing the blockage of the formation pores and channels, maintaining the permeability of the formation, ensuring the reinjection capacity, effectively avoiding the accumulation of water in the downhole oil-water separation device due to the deterioration of the water absorption capacity, thereby ensuring the smooth progress of subsequent mining operations and facilitating the long-term stable exploitation of the oilfield.

[0018] Furthermore, the crude oil solution of the present invention first undergoes preliminary separation by the first separation component and then enters the second separation component for in-depth separation. This multi-stage separation process can gradually remove the water in the crude solution, making the final rich oil solution have a lower moisture content compared to traditional mechanical single extraction, and the oil content in the rich water solution is also effectively controlled, improving the overall quality of oil-water separation.

[0019] Furthermore, by separately obtaining the total flow rate, rich water flow rate, and rich oil flow rate of the crude oil solution and determining the swirling parameters of the separation part based on these flow rate data, precise control of the separation process can be achieved, optimizing the separation effect of the crude oil solution, improving oil recovery rate, reducing production costs, and improving the overall quality of oil-water separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural block diagram of the downhole oil-water separation device based on the composite technology in the embodiment of the present invention; Figure 2 It is a structural schematic diagram of the downhole oil-water separation device based on the composite technology in the embodiment of the present invention; Figure 3 It is a structural schematic diagram of the first separation component in the embodiment of the present invention; Figure 4 It is a structural schematic diagram of the second separation component in the embodiment of the present invention; Figure 5 It is a structural schematic diagram of the sand suction pipe in the embodiment of the present invention; Figure 6 It is a structural schematic diagram of the reinjection part in the embodiment of the present invention; Figure 7 It is a structural schematic diagram of the liquid separation part in the embodiment of the present invention; Figure 8 It is a process schematic diagram of the downhole oil-water separation method based on the composite technology in the embodiment of the present invention; Figure 9 It is a structural schematic diagram of the reinjection measurement and adjustment short joint in the embodiment of the present invention.

[0021] In the figure, the liquid production part 1, the separation part 2, the electrode tube body 2-1, the spiral channel 2-2, the pipeline hole 2-3, the insulating end 2-4, the main swirl generator 2-5, the secondary swirl generator 2-6, the secondary liquid separation pipe 2-7, the secondary water separation port 2-8, the main liquid separation channel 2-9, the secondary liquid separation channel 2-10, the reinjection part 3, the reinjection three-way upper joint 3-1, the reinjection three-way lower joint 3-2, the reinjection three-way Venturi section 3-3, the secondary water separation port docking interface 3-4, the liquid separation part 4, the liquid inlet channel 4-1, the rich oil channel 4-2, the rich water channel 4-3, the liquid separation pipe 4-4, the sand suction pipe 5, the pressure sensor 6, the electric control measurement and adjustment valve 9-1, the measurement and adjustment control circuit 9-2, the measurement and adjustment short joint flow sensor 9-3, the main control circuit 9-4. Detailed Implementation Modes

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without any creative work belong to the scope of protection of the present invention.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installation", "connection", and "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0024] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, where the same or similar reference numerals indicate the same or similar elements or elements with the same or similar functions from beginning to end. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0025] To better understand the present invention, the following nouns in the present invention are explained: Crude oil: It refers to the initial liquid mixture directly extracted from underground oilstones to the ground through the drilling channel by pumping equipment or natural flow, etc., without any separation or purification processing. It may also contain water, solid particles (such as sand, mud, etc.), dissolved gas (such as methane, ethane, etc.), and other impurities.

[0026] Water-rich liquid: In downhole oil production operations, the water-rich liquid refers to the liquid phase part with a relatively high water content separated from the fluid produced from the oil well.

[0027] Oil-rich liquid: In downhole oil production operations, the oil-rich liquid refers to the liquid phase part with a relatively high oil content separated from the fluid produced from the oil well.

[0028] Please refer to Figure 1 and Figure 2 As shown, a downhole oil-water separation device based on a composite technology provided by the present invention includes: Liquid extraction part 1, which is used to obtain crude oil; Separation part 2, which is connected to the liquid extraction part 1 and includes a first separation component and a second separation component, and is used to enrich the crude oil to obtain a water-rich liquid and an oil-rich liquid; A reinjection section 3, which is connected to the separation section 2 and is used to reinject the water-rich liquid; A liquid separation section 4, which is connected to the separation section 2 and the reinjection section 3, includes a Y-shaped joint and a liquid separation pipe to converge and lift the oil-rich liquid to the ground surface.

[0029] Please refer to Figure 3 As shown, the first separation component in the separation section includes: The first separation component is composed of an electrode tube body 2-1, a spiral channel 2-2, a pipe hole 2-3, and an insulating end 2-4; Among them, the pipe holes 2-3 are arranged at equal intervals on the electrode tube body 2-1; The insulating end 2-4 is arranged at one end of the electrode tube body 2-1; The spiral channel 2-2 is arranged in the electrode tube body 2-1 in a spiral channel form.

[0030] It can be understood that the above-mentioned insulating end 2-4 can be located at the upper end of the electrode tube body 2-1 or at the lower end of the electrode tube body 2-1.

[0031] In implementation, the electrode tube body 2-1 is a wear-resistant stainless steel tube body. The spiral channel 2-2 makes the liquid rise along a spiral path. The bottom of the electrode tube body 2-1 contacts the electrode connection contact to achieve electrical connection, weakening the interfacial film strength of the emulsion, promoting the collision and coalescence of water droplets, and finally coalescing into water droplets with larger particle sizes and separating from the crude oil. At the same time, the second separation component establishes a centrifugal condition through swirling, enabling the denser sand grains to be thrown out of the electrode tube body 2-1 through the pipe holes 2-3 to the outside. The insulating end 2-4 abuts against the lower structural step of the liquid separation section, realizing the combination of the separation section and the liquid separation section, providing a prerequisite for obtaining the oil-rich liquid subsequently.

[0032] Please refer to Figure 4 As shown, the second separation component in the separation section includes: The second separation component includes a main swirl generator 2-5, an auxiliary swirl generator 2-6, an auxiliary liquid separation pipe 2-7, and an auxiliary water separation port 2-8; Among them, the main swirl generator 2-5 is arranged inside and above the main liquid separation channel 2-9, the auxiliary swirl generator 2-6 is arranged inside and below the auxiliary liquid separation channel 2-10, and the main liquid separation channel 2-9 is connected to the auxiliary liquid separation channel 2-10; The auxiliary liquid separation pipe 2-7 is arranged inside the auxiliary liquid separation channel 2-10 and above the auxiliary swirl generator 2-6; The auxiliary water separation port 2-8 is arranged below the auxiliary liquid separation pipe 2-7 and on the side away from the main swirl generator 2-5.

[0033] In a specific embodiment, the main swirl generator 2-5 causes the ionized oil-water mixture to swirl, making the fluid rotate. The Venturi section provided in the main liquid separation channel 2-9 serves to accelerate the fluid on the one hand, providing lifting power for the oil-rich liquid in the secondary liquid separation pipe 2-7; on the other hand, it provides a structural step to tightly hold the electrode tube body. The secondary water outlet 2-8 is where the water-rich liquid of the swirling liquid of the secondary swirl generator 2-6 enters the secondary liquid separation channel 2-10, connected to the interface of the secondary water outlet 2-8 to transfer the water-rich liquid to the reinjection tee.

[0034] The present invention adopts a composite separation technology that combines mechanical swirl separation and electroseparation. After electroseparation, the degree of emulsification is reduced. Compared with traditional primary separation, the present invention innovatively adds mechanical swirl separation, making the crude oil separation more thorough and greatly reducing the risk of crude oil blocking the reinjection formation. At the same time, the technologies of swirl sand separation, sand settling, and sand suction are adopted to minimize the presence of sand in the process, reducing the risks of wear and sand blockage of the reinjection formation. Compared with traditional oil extraction tools, the present invention has a higher recovery efficiency, extends the service life of the overall device, and reduces the failure and maintenance costs.

[0035] Please refer to Figure 5 As shown, a sand suction pipe is tightly attached to the outside of the spiral channel; Among them, a pressure sensor 6 is provided at the bottom of the sand suction pipe 5.

[0036] Please continue to refer to Figure 5 As shown, the sand suction pipe 5 has a structure with a closed bottom, an open upper end, and one side open. The open side of the sand suction pipe 5 is fitted with a pipe hole provided on the electrode tube body to collect the sand and gravel in the crude oil stock solution screened out through the pipe hole.

[0037] In one embodiment, an external sand suction pump is connected to the open upper end of the sand suction pipe 5. When the pressure of the sand and gravel received by the pressure sensor 6 is greater than its set threshold, the sand suction pump is started to clean and suck the accumulated sand and gravel in the sand suction pipe 5, so as to reduce the wear caused by sand and gravel on the inner wall of the downhole oil-water separation device.

[0038] The present invention effectively collects the sand and gravel in the crude oil stock solution by setting a sand suction pipe outside the spiral channel and fitting the open side of the sand suction pipe with a pipe hole on the electrode tube body. During the swirling of the oil by the swirl generator, the sand and gravel enter the sand suction pipe due to centrifugal force and are automatically separated, avoiding the accumulation of sand and gravel in the separation device and rubbing against the inner wall, thereby significantly reducing the wear degree of the inner wall of the downhole oil-water separation device, extending the service life of the equipment, effectively avoiding the problems of swirl failure or leakage, and further improving the underwater oil production efficiency.

[0039] Furthermore, the separated sand and gravel are discharged in time through the sand suction pipe, which prevents the blockage of formation pores and channels, maintains the permeability of the formation, ensures the reinjection capacity, and avoids the deterioration of water absorption capacity leading to water accumulation in the downhole oil-water separation device, thereby ensuring the smooth progress of subsequent mining operations and facilitating the long-term and stable mining of the oil field.

[0040] It is understandable that the threshold value of the pressure sensor 6 in the above embodiment can be set according to the size of the sand suction pipe and the density of the sand and gravel. For example, the diameter of the sand suction pipe 5 is 50 mm, and its internal space is relatively small. After analyzing the sand and gravel samples of the target oil field, it is determined that the density of the sand and gravel in the area is about 2.5 g / cm 3 Based on the sand suction pipe size and sand density, the threshold of pressure sensor 6 is set to 5 kPa. When the sand pressure on pressure sensor 6 exceeds 5 kPa, the sand pump starts to remove the sand accumulated in the sand suction pipe 5, thereby reducing the wear of the inner wall of the downhole oil-water separator caused by sand and gravel.

[0041] See also Figure 6 As shown, the reinjection part includes a reinjection tee upper joint 3-1, a reinjection tee lower joint 3-2, a reinjection tee venturi section 3-3 and a secondary water diversion port docking port 3-4; The upper connector 3-1 of the reinjection tee is connected to the lower connector 3-2 of the reinjection tee via the venturi section 3-3 of the reinjection tee. The auxiliary water diversion port docking port 3-4 is arranged in the middle of the reinjection three-way venturi section 3-3, and is connected to the auxiliary water diversion port so that the water-rich liquid can be reinjected into the reinjection part.

[0042] It can be understood that the materials used for the above-mentioned reinjection tee upper joint 3-1, reinjection tee lower joint 3-2, reinjection tee Venturi section 3-3 and auxiliary water diversion port docking interface 3-4 can be arbitrarily matched with existing technology according to the actual use conditions of the downhole oil-water separation device, and will not be elaborated here.

[0043] During implementation, the upper joint of the reinjection tee and the lower joint of the reinjection tee are connected through the Venturi section of the reinjection tee, which enhances the overall stability and can withstand the pressure and impact force in the complex downhole environment. The Venturi section can evenly disperse the fluid pressure, enhance the structural strength, improve the reliability and extend the service life. The auxiliary water diversion port docking interface is located in the middle of the Venturi section of the reinjection tee and is connected to the auxiliary water diversion port. The auxiliary water diversion port docking interface receives the water-rich liquid from the auxiliary water diversion port to provide lifting and migration power, and can accurately guide the water-rich liquid into the reinjection part, so that the flow direction and flow of the water-rich liquid can be controlled, avoiding leakage and flow direction errors, and greatly optimizing the reinjection process.

[0044] It is connected to the secondary water diversion port through the secondary water diversion port connection interface, which can accurately reinject a large amount of water-rich liquid generated during mining into the formation, avoid wasting water resources caused by direct discharge, and enable the reuse of water resources that were originally unable to be reused. At the same time, the reinjected water-rich liquid can supplement the formation energy, maintain pressure balance, facilitate subsequent mining, and re-participate in the groundwater cycle, improving the water resource recycling rate. In addition, the reuse of the reinjected water-rich liquid reduces the dependence on fresh water during the mining process.

[0045] Please refer to Figure 7 As shown, the Y-shaped joint consists of a liquid inlet channel 4-1, a rich oil channel 4-2, and a rich water channel 4-3; Among them, the liquid inlet channel 4-1 and the rich oil channel 4-2 have the same pipe diameter, and the rich oil channel 4-2 is arranged above the liquid inlet channel 4-1; The rich water channel 4-3 is arranged at the branch end of the Y-shaped joint, and the liquid separation pipe 4-4 is arranged between the rich oil channel 4-2 and the rich water channel 4-3.

[0046] In implementation, the rich oil liquid separated by the cyclone separation in the separation part is lifted upward from the rich oil channel 4-2 to the ground. The liquid separation pipe 4-4 is installed inside the main body of the Y-shaped joint. The liquid enters from the liquid inlet channel 4-1, and the rich oil liquid is separated by using cyclone separation. The centripetal force F = volume V • density ρ • angular velocity ω 2 • rotation radius r. Therefore, under the same centripetal force, the water-rich liquid with a large density will undergo centrifugal motion, so that the water-rich liquid with a large density is on the outside and the oil-rich liquid with a small density is on the inside. The two are separated through the liquid separation pipe 4-4. The rich oil liquid enters the rich oil channel 4-2 through the central channel of the liquid separation pipe 4-4, and the rich water liquid enters the rich water channel 4-3 through the side channel of the liquid separation pipe 4-4 and is connected to the upper joint of the reinjection three-way.

[0047] Please refer to Figure 8 As shown, this embodiment also provides an underground oil-water separation method based on a composite technology, which is applied to the above-mentioned underground oil-water separation device based on a composite technology, including: Obtain the original petroleum liquid; The original petroleum liquid is enriched by the separation part to obtain a water-rich liquid and an oil-rich liquid; The oil-rich liquid enters the liquid separation part to converge and rise to the ground surface; The water-rich liquid enters the reinjection part to be reinjected into the formation.

[0048] Respectively obtain the total flow rate of the original petroleum liquid, the water-rich flow rate of the water-rich liquid reinjected into the formation, and the oil-rich flow rate of the oil-rich liquid lifted to the ground surface.

[0049] It can be understood that the above-mentioned obtaining of the total flow rate of the original petroleum liquid, the water-rich flow rate of the water-rich liquid reinjected into the formation, and the oil-rich flow rate of the oil-rich liquid lifted to the ground surface can all be realized according to the flow rate monitor in the prior art. Exemplarily, please refer toFigure 9 The flow measurement and adjustment sub - section: The flow sensor 9 - 3 of the flow measurement and adjustment sub - section collects fluid flow data in real - time and converts it into an electrical signal. After receiving the signal, the flow measurement and control circuit 9 - 2 performs filtering, amplification, and digital processing to ensure data accuracy. The main control circuit 9 - 4 integrates the processed data, calculates the instantaneous flow and cumulative flow values in combination with preset parameters, and corrects the flow error through a built - in algorithm. At the same time, the electronically controlled flow measurement and adjustment valve 9 - 1 serves as a fluid channel and remains fully open so that the flow sensor 9 - 3 of the flow measurement and adjustment sub - section can accurately collect fluid flow data. The four components cooperate to accurately obtain flow data.

[0050] In the device of the present invention, specifically, a total flow measurement and adjustment sub - section is set in the liquid production section to obtain the total flow of the crude oil. An oil - quantity test tool is installed at the connection of the rich - oil channel to the external wellhead to obtain the rich - oil flow. A reinjection flow measurement and adjustment sub - section is set at the lower joint of the reinjection tee in the reinjection section to obtain the rich - water flow.

[0051] Determine the swirling parameters of the separation section according to the total flow, rich - oil flow, and rich - water flow; The swirling parameter S is determined by the following formula:

[0052] where S is the swirling parameter, Q 油 is the rich - oil flow, Q 水 is the rich - water flow, Q 总 is the total flow, α is the weight coefficient, reflecting the dominant role of fluid physical properties in swirl separation, determined according to the separation target, and k is the exponential parameter, reflecting the influence degree of rich - oil flow and rich - water flow on swirl separation, determined according to the fluid properties.

[0053] Generally, the value range of the swirling parameter S is 1.5 - 5.0, the value range of the weight coefficient α is 0.5 - 2, and the value range of the exponential parameter k is 0.8 - 1.5. By determining the value of the weight coefficient α and the exponential parameter k, the total flow Q 总 is adjusted to ensure that the swirling parameter S is within the corresponding reasonable value range.

[0054] Specifically, the weight coefficient α balances the proportion of oil - water flow. When the rich - oil flow dominates (such as when the oil - phase proportion is 70%), α≥0.5 can be taken to strengthen the oil - phase separation. When the rich - water flow dominates (such as when the water - phase proportion is 70%), 1 < α≤2 is taken to preferentially ensure the water - phase separation. When the flow fluctuates greatly, α = 1.2 to balance the dynamic adaptability. Especially, when the proportions of the oil phase and the water phase are the same, that is, the proportion is 50%, the weight coefficient α = 1.

[0055] The value of the exponential parameter k is determined according to the fluid properties. If the non-linear influence of the liquid flow rate is significant (such as the sudden drop in the swirl separation efficiency caused by flow rate fluctuations), k≥0.8 can be taken. If the flow rate influence is linear, k = 1.0 is taken to simplify the control. For fluids with high viscosity or high density difference, k≤1.5 is taken to reduce the flow rate interference.

[0056] The value of the swirl parameter S needs to be adjusted according to the fluid viscosity and solid content. For low-viscosity fluids (such as light oil) without solids, when the viscosity is 1000 cp, the value of S is 1.5. For high-viscosity fluids with solid content (such as heavy oil) with a viscosity of 5000 cp, the value of S is 5.0 to avoid clogging of the swirl separation channel.

[0057] The formula design of the swirl parameter S is based on the coupling effect of fluid dynamics and multiphase flow separation mechanism in the swirl separation process. Its core principle is to quantify the dominant influence of fluid physical properties (such as density difference, viscosity, interfacial tension) on the separation efficiency through the weight coefficient α, and to characterize the non-linear effect degree of the flow rate (oil-rich flow rate Q_oil, water-rich flow rate Q_water) on the tangential velocity and centrifugal force distribution of the swirl field through the exponential parameter k. Among them, α increases when the oil phase is dominant to strengthen the oil phase separation, increases when the water phase is dominant to give priority to ensuring the water phase separation, and takes the value of 1 when the oil and water are balanced to balance the separation. And k adjusts the influence weight of the flow rate on the separation efficiency according to the fluid viscosity fluctuation characteristics (k≥0.8 for non-Newtonian fluids or high-turbulence conditions, k = 1.0 for linear stable conditions, k≤1.5 for high-viscosity / high-density difference fluids). Finally, the value range of S (1.5 - 5.0) is used to match the fluid viscosity and solid content (low value for low-viscosity without solids, high value for high-viscosity with solids) to optimize the flow field distribution in the swirl separation channel, avoid clogging and improve the oil-water separation efficiency.

[0058] It can be understood that the swirl parameter is a dimensionless parameter that describes the rotation intensity or swirl characteristics of the crude oil when it enters the separation section. It reflects the relative relationship between the tangential velocity and the axial velocity in the fluid flow, that is, the driving ability of the main swirl generator and the auxiliary swirl generator to rotate the crude oil. The larger the swirl parameter, the more intense the rotation of the corresponding crude oil in the separation section, and the stronger the separation effect of sand and water in the crude oil.

[0059] By separately obtaining the total flow rate, water-rich flow rate, and oil-rich flow rate of the crude oil, and determining the swirl parameter of the separation section according to these flow rate data, the precise control of the separation process can be realized, the separation effect of the crude oil can be optimized, the oil recovery rate can be increased, the production cost can be reduced, and the overall quality of the oil-water separation can be improved.

[0060] In a complete embodiment, the original oil is lifted upward along the oil pipe. The total flow rate of the original oil is obtained through the total flow rate monitoring short joint. The produced liquid is lifted into the first separation assembly. Under the action of the DC electric field of the electrode tube body, the interfacial film strength of the emulsion is weakened, promoting the collision and coalescence of water droplets, which finally coalesce into larger water droplets and are separated from the original oil. At the same time, the rotational flow of the main swirl generator in the second separation assembly causes the sand grains with high density to be thrown out of the pipe and enter the sand suction pipe. At this time, some oil-containing liquid still flows out of the electrode tube body and enters the auxiliary liquid separation channel. Through the action of the auxiliary swirl generator and the auxiliary liquid separation pipe, the oil-rich part converges into the main fluid under the lifting force provided by the Venturi section, and the water-rich part enters the reinjection tee through the auxiliary water separation port.

[0061] After the fluid separated by ionization passes through the Venturi section, it enters the main liquid separation channel. Through the swirling action of the main swirl generator, mechanical swirl separation is carried out on the oil-water mixture. At the Y-joint, the oil-rich liquid continues to be lifted upward to the ground oil-rich flow rate. At the same time, the oil-rich monitoring short joint obtains the oil-rich flow rate. The water-rich liquid is diverted to the reinjection section and reinjected into the formation through the upper joint and the lower joint of the reinjection tee. At the same time, the water-rich monitoring short joint obtains the water-rich flow rate, and determines the swirling parameters of the separation section according to the total flow rate, the oil-rich flow rate, and the water-rich flow rate, so as to make the split ratio reach the optimal state.

[0062] After working for a period of time, when the pressure sensor reaches the threshold value, the external sand suction pump is started, and the sand grains accumulated in the well are sucked out through the sand suction pipe.

[0063] The components involved in the embodiments described in this application can be implemented in a hardware manner or in a software manner. The described components can also be set in the system. For example, it can be described as: a downhole oil-water separation system based on composite technology includes a liquid production unit, a separation unit, a reinjection unit, and a liquid separation unit. Among them, the names of these units do not constitute a limitation to the component itself in some cases.

[0064] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functions, and operations that the systems and methods according to various embodiments of the present application may implement. In this regard, each block in the flowchart or block diagram may represent a module, a segment of a program, or a part of code that contains one or more executable instructions for implementing a specified logical function. It should also be noted that, in some alternative implementations, the functions marked in the blocks may occur in a different order than that marked in the accompanying drawings. For example, two consecutive blocks shown may actually be executed substantially in parallel, and they may sometimes be executed in the reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and combinations of blocks in the block diagram and / or flowchart, may be implemented by a dedicated hardware-based device that performs the specified functions or operations, or may be implemented by a combination of dedicated hardware and computer instructions.

[0065] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or variations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. Downhole oil-water separation device based on composite technology, characterized in that, Comprising: A liquid extraction part for obtaining crude oil. A separation part connected to the liquid extraction part, including a first separation component and a second separation component, for enriching the crude oil to obtain a water-rich liquid and an oil-rich liquid. An injection part connected to the separation part for injecting the water-rich liquid back. A liquid separation part connected to the separation part and the injection part, including a Y-shaped joint and a liquid separation pipe, for converging and lifting the oil-rich liquid to the ground. The first separation component in the separation part includes: The first separation component is composed of an electrode tube body, a spiral channel, a pipe hole, and an insulating end. Wherein, the pipe holes are arranged at equal intervals on the electrode tube body. The insulating end is arranged at one end of the electrode tube body. The spiral channel is arranged in a spiral shape inside the electrode tube body. The second separation component in the separation part includes: The second separation component includes a main swirl generator, a secondary swirl generator, a secondary liquid separation pipe, and a secondary water separation port. Wherein, the main swirl generator is arranged inside and above the main liquid separation channel, the secondary swirl generator is arranged inside and below the secondary liquid separation channel, and the main liquid separation channel is connected to the secondary liquid separation channel. The secondary liquid separation pipe is arranged inside the secondary liquid separation channel and above the secondary swirl generator. The secondary water separation port is arranged below the secondary liquid separation pipe and on the side away from the main swirl generator. A sand suction pipe is tightly attached to the outside of the spiral channel. Wherein, a pressure sensor is arranged at the bottom of the sand suction pipe. The sand suction pipe has a structure with a closed bottom, an open upper end, and an open side. The open side of the sand suction pipe is fitted with the pipe hole arranged on the electrode tube body to collect the sand and gravel in the crude oil screened out by the pipe hole.

2. The downhole oil-water separation device based on the composite technology according to claim 1, characterized in that, The injection part includes an injection three-way upper joint, an injection three-way lower joint, an injection three-way Venturi section, and a secondary water separation port docking interface. Wherein, the injection three-way upper joint is connected to the injection three-way lower joint through the injection three-way Venturi section. The secondary water separation port docking interface is arranged in the middle of the injection three-way Venturi section and is connected to the secondary water separation port to enable the water-rich liquid to be injected back into the injection part.

3. The downhole oil-water separation device based on the composite technology according to claim 2, characterized in that, The Y-shaped joint is composed of a liquid inlet channel, an oil-rich channel, and a water-rich channel. Wherein, the liquid inlet channel and the oil-rich channel have the same diameter, and the oil-rich channel is arranged above the liquid inlet channel. The water-rich channel is arranged at the branch end of the Y-shaped joint, and the liquid separation pipe is arranged between the oil-rich channel and the water-rich channel.

4. Downhole oil-water separation method based on composite technology, characterized in that, Applied to the downhole oil-water separation device based on the composite technology according to any one of claims 1-3, including: Obtaining crude oil. The crude oil is enriched by the separation part to obtain a water-rich liquid and an oil-rich liquid. The oil-rich liquid enters the liquid separation part to converge and lift to the ground. The water-rich liquid enters the injection part to be injected back into the formation.

5. The downhole oil-water separation method based on the composite technology according to claim 4, characterized in that, Respectively obtain the total flow rate of the crude oil, the water-rich flow rate of the water-rich liquid injected back into the formation, and the oil-rich flow rate of the oil-rich liquid lifted to the ground.

6. The downhole oil-water separation method based on the composite technology according to claim 5, characterized in that, Determine the swirl parameters of the separation part according to the total flow rate, the oil-rich flow rate, and the water-rich flow rate.

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