Tubular composite fixed defoaming device and defoaming method

Abstract

The invention relates to a tubular composite fixed defoaming device and a defoaming method, which are used for defoaming shale gas produced liquid. The device comprises a tubular shell, a shale gas produced liquid inlet is formed in one end of the tubular shell, an outlet is formed in the other end of the tubular shell, and a three-stage defoaming structure of a Laval pipe assembly, a defoaming barrel and a cyclone which are sequentially arranged in the flowing-in direction of the shale gas produced liquid is arranged in the tubular shell. Compared with the prior art, physical and chemical combined defoaming is adopted, a filling device, a power source and ground construction do not need to be matched, the earlier-stage investment is reduced, the device does not need to be maintained and inspected, operation is not affected by low temperature, only the defoaming rods need to be regularly filled, and the defoaming efficiency is greatly improved. And the system can be combined with existing shale gas production platform equipment, so that the dependence of a foam drainage process on water resources is reduced.

Description

Technical Field

[0001] This invention relates to a defoaming device, and more particularly to a tubular composite fixed defoaming device and defoaming method. Background Technology

[0002] Shale gas is a "man-made gas reservoir," and fluid accumulation in the low-pressure stage is a major factor limiting well productivity. Foam drainage gas production technology is widely used as an auxiliary fluid removal process in shale gas wells during the low-pressure stage. The main principle of foam drainage is that after mixing a foaming agent with the wellbore fluid, the agitation of natural gas generates a large amount of low-density water-bearing foam, transforming the wellbore fluid into a foamy fluid and lowering the critical fluid carrying capacity. After implementing foam drainage gas production technology, defoaming equipment must be installed at the gas production surface to prevent foam from carrying fluid into downstream gathering and processing stations, which could lead to decreased pipeline efficiency, dehydration tower failure, and substandard product gas dew point.

[0003] Currently, the main defoaming process in the natural gas extraction industry is liquid defoaming, which involves injecting a liquid defoamer of a certain concentration into the surface process. Shale gas wells are characterized by low gas production and low pressure. Liquid defoaming requires corresponding equipment and maintenance personnel, resulting in high costs and hindering efficient development under low-production conditions. Liquid defoaming requires both a one-time expenditure on equipment procurement and long-term costs for chemicals and labor maintenance. Furthermore, its use necessitates periodic replenishment of chemicals and clean water, chemical preparation, equipment maintenance, and monitoring and inspection, leading to a significant overall workload on-site. Low ambient temperatures can also cause the injection process to freeze, preventing normal operation. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art by providing a tubular composite fixed defoaming device and defoaming method. This invention uses a combination of physical and chemical defoaming, eliminating the need for a matching filling device, power supply, and ground construction, thus reducing initial investment. Furthermore, the device requires no maintenance or inspection, is unaffected by low temperatures, and only requires periodic filling of defoaming rods for long-lasting defoaming.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] The first aspect of the present invention provides a tubular composite fixed defoaming device, comprising a tubular shell, one end of which is a shale gas produced fluid inlet and the other end of which is a shale gas produced fluid outlet.

[0007] The tubular shell is equipped with a three-stage defoaming structure, which, along the flow direction of the shale gas produced fluid, includes a Laval tube assembly, a defoaming cylinder, and a hydrocyclone in sequence.

[0008] The Laval tube assembly includes multiple parallel Laval tubes. Shale gas produced fluid entering from one end of the tubular shell first enters the Laval tube assembly for the first stage of defoaming.

[0009] The defoaming cylinder includes at least one screen tube and a fixed defoaming rod disposed in the screen tube. The defoaming cylinder performs a second-stage defoaming on the shale gas produced fluid passing through the Laval tube assembly.

[0010] The hydrocyclone achieves third-stage defoaming by using the centrifugal force, extrusion force, and airflow shear stress generated by the rotational motion of the shale gas produced fluid.

[0011] Furthermore, the tubular shell is a steel round tube, and the Laval tube assembly, defoaming cylinder, and cyclone separator are all detachably connected to the tubular shell.

[0012] Furthermore, the Laval tube assembly also includes a carrier plate, which is connected to the inner wall of the tubular housing, and multiple Laval tubes are connected to the carrier plate.

[0013] Furthermore, the carrier plate is circumferentially perpendicular to the tubular shell, and the carrier plate is perpendicular to the flow direction of the shale gas produced fluid.

[0014] Furthermore, the carrier plate is provided with multiple through holes, and each Laval tube passes through the through hole and is connected to the carrier plate.

[0015] Furthermore, the Laval tube includes a gradually narrowing converging section, a gradually widening diffuser section, and a throat straight section located between the converging section and the diffuser section.

[0016] Furthermore, the sieve tube is uniformly provided with a plurality of sieve holes;

[0017] A fixed defoaming rod is placed inside the screen tube. Shale gas produced fluid flows through the screen tube channel and comes into contact with the solid defoaming rod. The foam liquid in the airflow dissolves part of the solid defoaming rod to achieve defoaming.

[0018] Furthermore, the defoaming rod is one of the following: polysiloxane defoaming material, organosilicon polyether defoaming material, or cyanoalkyl polysiloxane defoaming material.

[0019] Furthermore, the hydrocyclone is a hydrocyclone.

[0020] A second aspect of the present invention provides a tubular composite fixed defoaming method, implemented by the device described above, comprising the following steps:

[0021] Shale gas produced fluid is introduced into the tubular shell through the inlet and enters the Laval tube assembly. The converging section of the Laval tube accelerates and depressurizes the fluid, while the throat section generates turbulence, causing the foam to burst due to the internal and external pressure difference and the turbulent effect.

[0022] The fluid treated by the Laval tube enters the defoaming cylinder and comes into contact with the solid defoaming rod placed inside through the sieve holes on the defoaming cylinder. The foam liquid in the fluid dissolves part of the solid defoaming rod to achieve chemical defoaming.

[0023] The fluid exiting the defoaming cylinder enters the hydrocyclone, where the centrifugal force, extrusion force, and airflow shear stress generated by the hydrocyclone further separate the bubbles in the fluid, thus effectively eliminating the foam.

[0024] When the consumption of solid defoaming rods in the defoaming cylinder exceeds a preset percentage, the solid defoaming rods in the defoaming cylinder are replaced.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1) This invention adopts a combination of physical and chemical defoaming methods, and achieves defoaming through its own structure. It does not require supporting filling devices, power supply and ground construction, which greatly reduces the capital investment in the early stage of defoaming process and effectively alleviates the cost pressure of enterprises in equipment procurement and construction.

[0027] 2) In this invention, chemical defoaming relies on natural gas to carry liquid to dissolve solid defoaming rods, eliminating the need for additional chemicals and water, as well as the need for chemical preparation. This not only reduces the dependence of foam drainage process on water resources, but also avoids the costs of purchasing, transporting and storing chemicals due to the use of liquid defoamers, while reducing expenses related to water supply and treatment.

[0028] 3) As a built-in device in containers or pipelines, this invention requires no maintenance or inspection, which can significantly save labor costs and maintenance expenses, and reduce the human and material resources that enterprises need to invest in equipment maintenance and management.

[0029] 4) After commissioning, only the solid defoaming sticks need to be filled periodically, with no other additional costs. Moreover, the solid defoaming sticks have a significantly longer working time than liquid defoamers, providing long-lasting defoaming and significantly reducing the frequency and cost of using defoaming agents. In the long run, the economic benefits are significant.

[0030] 5) The operation of the defoaming device is not affected by the low temperature environment and has strong environmental adaptability. It can work stably in cold regions or complex climatic conditions, ensuring the continuity and stability of the production process and reducing the risk of production interruption due to environmental factors.

[0031] 6) The present invention has a regular shape and simple structure, and can be directly built into containers such as separators and desanders in the already operational shale gas production platform without the need for secondary construction and modification. This greatly improves the applicability and ease of installation of the device, reduces the need to modify existing production facilities, saves modification time and costs, and facilitates the rapid upgrading and optimization of the defoaming function. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the tubular composite fixed defoaming device of the present invention.

[0033] In the diagram: 1. Tubular shell, 2. Laval tube assembly, 3. Defoamer, 4. Hydrocyclone, 5. Laval tube, 6. Fixed defoamer rod. Detailed Implementation

[0034] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. Component models, material names, connection structures, control methods, algorithms, and other features not explicitly described in this technical solution are considered common technical features disclosed in the prior art.

[0035] Example 1

[0036] This embodiment provides a tubular composite fixed defoaming device, see [link]. Figure 1 It includes a tubular shell 1, one end of which is a shale gas produced fluid inlet and the other end is a shale gas produced fluid outlet.

[0037] The tubular shell 1 is equipped with a three-stage defoaming structure. The three-stage defoaming structure includes, in sequence, a Laval tube assembly 2, a defoaming cylinder 3, and a hydrocyclone 4 along the shale gas produced fluid inflow direction.

[0038] The following is a description of each structure in this embodiment:

[0039] Tubular shell 1

[0040] Description: The external structure of the entire tubular composite fixed defoaming device is cylindrical in shape and made of steel. It provides housing for the internal defoaming structure, and also has inlet and outlet for shale gas produced fluid. It is the part that connects the entire device to the external pipeline.

[0041] Function: Protects internal components and guides the flow of shale gas produced fluid into and out of the device.

[0042] Laval tube assembly 2

[0043] Description: Located inside the tubular shell 1, it is the first stage in a three-stage defoaming structure. It consists of multiple parallel Laval tubes 5 and also includes a carrier plate. The carrier plate is connected to the inner wall of the tubular shell 1, and the multiple Laval tubes 5 pass through and connect to the through holes on the carrier plate. The carrier plate is perpendicular to the circumference of the tubular shell 1 and to the flow direction of the shale gas produced fluid.

[0044] Function: Utilizing the special structure of the Laval tube 5, the foam in the incoming shale gas produced fluid is initially defoamed. The fluid is accelerated and depressurized through the converging section of the Laval tube 5, and turbulence is generated in the throat section, causing the foam to burst due to the internal and external pressure difference and the effect of turbulence.

[0045] Defoaming tube 3

[0046] Description: This is the second stage of the three-stage defoaming structure inside the tubular shell 1. It includes at least one screen tube with multiple screen holes evenly distributed on it, and a fixed defoaming rod 6 is placed inside. A snap-on opening can be provided at the end or middle of the screen tube to facilitate the replacement of the internal fixed defoaming rod 6.

[0047] Function: When the shale gas produced fluid after being processed by the Laval tube assembly 2 passes through the screen tube channel, the foam liquid in the gas flow will dissolve part of the solid defoaming rod 6, thus achieving chemical defoaming.

[0048] Cyclone 4

[0049] Description: As the third stage in the three-stage defoaming structure inside the tubular shell 1. In this invention, it can be a hydrocyclone, which generates centrifugal force, extrusion force, and gas flow shear stress on the shale gas produced fluid through rotational motion.

[0050] Function: To further defoam the shale gas produced fluid after passing through defoaming cylinder 3, so as to further separate the air bubbles in the fluid and thus achieve more thorough foam elimination.

[0051] Laval tube 5

[0052] Description: The components of the Laval tube assembly 2 include a gradually narrowing converging section, a gradually widening diffuser section, and a throat straight section located between the converging section and the diffuser section.

[0053] Function: Based on its special structural design, it generates turbulence by changing the pressure and flow rate of the fluid, thereby disrupting the stability of the foam and achieving the purpose of defoaming.

[0054] Fixed defoaming stick 6

[0055] Description: Placed inside the sieve tube of defoaming cylinder 3, it can be one of polysiloxane defoaming materials, organosilicon polyether defoaming materials, or cyanoalkyl polysiloxane defoaming materials.

[0056] Function: When the shale gas produced fluid flows through the screen tube channel of the defoaming cylinder 3, the foam liquid in the airflow dissolves part of the solid defoaming rod 6, reduces the surface tension of the foam liquid, and causes the foam to break, thus achieving chemical defoaming.

[0057] In specific implementation, the tubular shell 1 is a steel round tube, and the Laval tube assembly 2, defoaming cylinder 3, and cyclone separator 4 are all detachably connected to the tubular shell 1.

[0058] In a specific implementation, the Laval tube assembly 2 further includes a carrier plate, which is connected to the inner wall of the tubular shell 1, and multiple Laval tubes 5 are connected to the carrier plate. The carrier plate is perpendicular to the circumference of the tubular shell 1 and to the flow direction of the shale gas produced fluid.

[0059] The carrier plate has multiple through holes, and each Laval tube 5 passes through the through hole and is connected to the carrier plate.

[0060] In specific implementation, the screen tube is uniformly provided with multiple screen holes; a fixed defoaming rod 6 is placed inside the screen tube, and the shale gas produced fluid flows through the screen tube channel and comes into contact with the solid defoaming rod 6. The foam liquid in the airflow dissolves part of the solid defoaming rod 6, thereby achieving defoaming. The defoaming rod 6 is one of polysiloxane defoaming material, organosilicon polyether defoaming material, or cyanoalkyl polysiloxane defoaming material. The hydrocyclone 4 is a hydrocyclone.

[0061] In specific implementation, this embodiment also provides a tubular composite fixed defoaming method, including the following steps:

[0062] Shale gas produced fluid is introduced into the tubular shell 1 through the inlet and enters the Laval tube assembly 2. The converging section of the Laval tube accelerates the fluid and reduces its pressure, while the throat section generates turbulence, causing the foam to burst due to the internal and external pressure difference and the turbulent effect.

[0063] The fluid treated by the Laval tube enters the defoaming cylinder 3 and comes into contact with the solid defoaming rod 6 placed inside through the sieve holes on the defoaming cylinder. The foam liquid in the fluid dissolves part of the solid defoaming rod to achieve chemical defoaming.

[0064] The fluid coming out of the defoaming cylinder enters the hydrocyclone 4, where the centrifugal force, extrusion force and airflow shear stress generated by the hydrocyclone further separate the bubbles in the fluid, thus effectively eliminating the foam.

[0065] When the consumption of solid defoaming rods 6 in the defoaming cylinder 3 exceeds a preset percentage, the solid defoaming rods 6 in the defoaming cylinder 3 shall be replaced.

[0066] The following is a description of the mechanism of the working process of this invention:

[0067] Laval tube assembly 2 defoaming mechanism

[0068] Accelerated blood pressure reduction effect

[0069] When the shale gas produced fluid enters the converging section of Laval tube 5, according to the fluid continuity equation and Bernoulli's equation, the cross-sectional area of ​​the flow path continuously decreases, the fluid velocity gradually increases, and the gas pressure decreases accordingly. For foam, its internal pressure is relatively higher than the external pressure, and this pressure difference causes the bubbles to tend to expand.

[0070] Turbulent destructive effects

[0071] When the fluid passes through the straight section at the throat of the Laval tube 5, the flow velocity reaches its maximum value due to the abrupt change in pipe diameter. At this point, the fluid flow becomes extremely turbulent, generating strong turbulence. The eddies and irregular velocity changes in the turbulence exert powerful shear and impact forces on the foam. These forces disrupt the stability of the foam, causing bubbles to collide and merge. Under the combined effect of the internal and external pressure difference and turbulence, the surface film of the foam cannot maintain its intact structure, leading to the rupture of a large number of bubbles and achieving the initial defoaming process.

[0072] Defoaming cartridge 3 Chemical defoaming mechanism

[0073] Contact dissolution process

[0074] The fluid, after being processed by the Laval tube assembly 2, enters the defoaming cylinder 3. The fluid passes through the sieve holes on the sieve tube and comes into full contact with the solid defoaming rods 6 inside. The defoaming rods 6 are made of defoaming materials such as polysiloxane defoaming materials, organosilicon polyether defoaming materials, and cyanoalkyl polysiloxane defoaming materials. When the foam liquid comes into contact with the solid defoaming rods 6, due to the solubility of these materials in the foam liquid, the foam liquid will dissolve some of the solid defoaming rods 6.

[0075] Reduce surface tension to defoam

[0076] The surface properties of the foam liquid after dissolving component 6 of the defoaming stick are altered. The active ingredient in defoaming stick 6 reduces the surface tension of the foam liquid, disrupting the conditions for foam formation and stability. According to the theory of foam formation and stability, the reduction in surface tension accelerates the drainage rate of the foam film, thins the film, and ultimately leads to foam rupture, thus achieving the chemical defoaming process.

[0077] Hydrocyclone 4 Defoaming Mechanism

[0078] Centrifugal separation effect

[0079] The fluid exiting the defoaming cylinder 3 enters the hydrocyclone 4 and rotates at high speed inside. Based on the principle of centrifugal force, during rotation, the denser liquid is thrown towards the outer wall of the hydrocyclone 4, while the less dense gas accumulates in the center. This centrifugal force further separates any remaining bubbles from the liquid, reducing the gas content in the liquid.

[0080] Synergistic effect of compressive force and shear stress

[0081] Inside the hydrocyclone 4, the fluid is subjected to centrifugal force, as well as compressive force and airflow shear stress. These forces further disrupt the structure of residual bubbles, causing them to completely separate from the liquid, thus achieving more thorough defoaming. This ensures that the foam in the shale gas produced fluid after processing by the entire device is effectively eliminated, achieving the ideal defoaming effect.

[0082] Through the synergistic effect of the above three steps, this invention can effectively eliminate foam in shale gas produced fluid. Simultaneously, by monitoring the consumption of the solid defoaming rods 6 in the defoaming cylinder 3 and replacing them in a timely manner, the continuous effectiveness of the entire defoaming process can be ensured.

[0083] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A tubular composite fixed defoaming device, characterized in that, It includes a tubular shell (1), one end of which is the shale gas produced fluid inlet and the other end is the shale gas produced fluid outlet; The tubular shell (1) is equipped with a three-stage defoaming structure. The three-stage defoaming structure includes, in sequence, a Laval tube assembly (2), a defoaming cylinder (3), and a hydrocyclone (4) along the shale gas produced fluid inflow direction. The Laval tube assembly (2) includes multiple parallel Laval tubes (5). Shale gas produced fluid entering from one end of the tubular shell (1) first enters the Laval tube assembly (2) simultaneously for the first stage of defoaming. The defoaming cylinder (3) includes at least one screen tube and a fixed defoaming rod (6) disposed in the screen tube. The defoaming cylinder (3) performs a second-stage defoaming on the shale gas produced fluid passing through the Laval tube assembly (2). The hydrocyclone (4) achieves the third stage of defoaming by using the centrifugal force, extrusion force and airflow shear stress generated by the rotational motion of the shale gas produced fluid.

2. The tubular composite fixed defoaming device according to claim 1, characterized in that, The tubular shell (1) is a steel round tube, and the Laval tube assembly (2), defoaming cylinder (3), and cyclone separator (4) are all detachably connected to the tubular shell (1).

3. The tubular composite fixed defoaming device according to claim 1, characterized in that, The Laval tube assembly (2) also includes a carrier plate, which is connected to the inner wall of the tubular housing (1), and multiple Laval tubes (5) are connected to the carrier plate.

4. The tubular composite fixed defoaming device according to claim 3, characterized in that, The carrier plate is circumferentially perpendicular to the tubular shell (1), and the carrier plate is perpendicular to the flow direction of the shale gas produced fluid.

5. The tubular composite fixed defoaming device according to claim 3, characterized in that, The carrier plate is provided with multiple through holes, and each Laval tube (5) passes through the through hole and is connected to the carrier plate.

6. The tubular composite fixed defoaming device according to claim 1, characterized in that, The Laval tube (5) includes a gradually narrowing converging section, a gradually widening diffuser section, and a throat straight section located between the converging section and the diffuser section.

7. The tubular composite fixed defoaming device according to claim 1, characterized in that, The sieve tube is uniformly provided with multiple sieve holes; A fixed defoaming rod (6) is placed inside the screen tube. The shale gas produced fluid flows through the screen tube channel and comes into contact with the solid defoaming rod (6). The foam liquid in the airflow dissolves part of the solid defoaming rod (6) to achieve defoaming.

8. The tubular composite fixed defoaming device according to claim 7, characterized in that, The defoaming rod (6) is one of the following: polysiloxane defoaming material, organosilicon polyether defoaming material, or cyanoalkyl polysiloxane defoaming material.

9. The tubular composite fixed defoaming device according to claim 1, characterized in that, The hydrocyclone (4) is a hydrocyclone.

10. A tubular composite fixed defoaming method, characterized in that, Implemented by the apparatus as described in any one of claims 1 to 9, comprising the following steps: Shale gas produced fluid is introduced into the tubular shell (1) through the inlet and enters the Laval tube assembly (2). The converging section of the Laval tube accelerates the fluid and reduces its pressure. Turbulence is generated in the throat section, causing the foam to burst due to the pressure difference between the inside and outside and the turbulence. The fluid treated by the Laval tube enters the defoaming cylinder (3) and comes into contact with the solid defoaming rod (6) placed inside through the sieve holes on the defoaming cylinder. The foam liquid in the fluid dissolves part of the solid defoaming rod to achieve chemical defoaming. The fluid coming out of the defoaming cylinder enters the hydrocyclone (4), and the centrifugal force, extrusion force and airflow shear stress generated by the hydrocyclone further separate the bubbles in the fluid, thereby effectively eliminating the foam. When the consumption of solid defoaming rods (6) in the defoaming cylinder (3) exceeds a preset percentage, the solid defoaming rods (6) in the defoaming cylinder (3) shall be replaced.

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