A vertical drilling fluid gas-liquid separator and a gas-liquid separation method

Abstract

The application discloses a vertical drilling fluid gas-liquid separator and a gas-liquid separation method, relates to the field of gas-liquid separation of oil and natural gas development, and belongs to the gas-liquid separation field. The gas-liquid separator comprises a tank body, a fluid inlet channel in communication with the inside of the tank body, a drilling fluid discharge channel, and an exhaust port. The exhaust port is located at the top of the tank body, the fluid inlet channel is higher than the drilling fluid discharge channel, and the inside of the tank body is provided with a centrifugal separator and a baffling assembly. The centrifugal separator is in communication with the fluid inlet channel, and the baffling assembly is located below the centrifugal separator. The gas-liquid separation method based on the gas-liquid separator can continuously carry out four times of gas-liquid separation, thereby significantly improving the separation capacity of the gas phase, so as to solve the problem that the separation effect of the gas-liquid separator in the prior art is poor when the gas content in the drilling fluid is high, and the gas-liquid separator is especially suitable for use when the gas content in the drilling fluid is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas development, in particular to a vertical drilling fluid gas-liquid separator and a gas-liquid separation method. BACKGROUND

[0002] The degassing separation system of the drilling fluid is to remove a large amount of gas and solid impurities contained in the drilling fluid (i.e. mud) returned from the downhole through a separator. The gas phase impurities that need to be removed are mixed gases overflowing from the formation into the well during drilling, which contain combustible or harmful gases such as natural gas, hydrogen, hydrogen sulfide, etc. When the content of such mixed gases is high, the returned drilling fluid can enter the solid control system to remove solid impurities only after degassing treatment.

[0003] The purpose of removing gas from the drilling fluid is at least two aspects. One is to remove impurities from the drilling fluid, which is beneficial to recycling, improves utilization rate, reduces drilling operation cost and improves productivity. The second is that a large amount of gas is mixed or dissolved in the drilling fluid, and if the gas removal rate is low, it will cause changes in drilling fluid density and other properties, which will not achieve the purpose of cooling and cleaning when returning to the downhole operation, resulting in drilling risks. The gas separated from the returned drilling fluid is treated by ignition or discharge at a designated location, and the drilling fluid after degassing treatment enters the subsequent solid-liquid separation equipment for solid-liquid separation treatment.

[0004] However, the drilling fluid degassing separation system in the prior art at least has the following defects: (1) when drilling gas wells or drilling high-gas reservoirs, the gas content in the drilling fluid will increase significantly. The structure of the separator widely used in the current operation site is simply based on the principle of gravity impact to separate the drilling fluid. The separated drilling fluid still contains a large amount of gas phase, and the separation effect is limited, which is difficult to meet the working requirements when the gas content is high; (2) when the gas content is high, the internal pipeline of the existing drilling fluid gas-liquid separator is prone to pipeline oscillation; when the flow rate is large, it even causes obvious oscillation of the tank body of the separator, which is not conducive to the safety and stability of the operation; (3) the centrifugal separator for degassing of the drilling fluid in the prior art, such as the cyclone separator, has the phenomena of liquid carrying at the gas outlet and gas entraining at the liquid outlet during operation, especially when the drilling fluid to be treated contains a large amount of gas, the separation effect will be greatly reduced; at the same time, the viscosity of the returned drilling fluid is generally large, which further leads to poor effect of the traditional centrifugal degassing method.

[0005] In summary, the gas-liquid separator for degassing of the drilling fluid in the prior art has the problem of poor separation effect when the gas content in the drilling fluid is high, and it is necessary to improve and optimize it. SUMMARY

[0006] The application provides a vertical drilling fluid gas-liquid separator and a gas-liquid separation method, and aims at solving the problem of poor separation effect of the gas-liquid separator in the prior art when the gas content in the drilling fluid is high.

[0007] The application achieves the above purposes by the following technical scheme:

[0008] The vertical drilling fluid gas-liquid separator comprises a tank body, a fluid inlet channel, a drilling fluid outlet channel and an exhaust port, the fluid inlet channel is in communication with the inside of the tank body, the exhaust port is located at the top of the tank body, the fluid inlet channel is higher than the drilling fluid outlet channel, and the inside of the tank body is provided with a centrifugal separator and a baffle assembly, the centrifugal separator is in communication with the fluid inlet channel, and the baffle assembly is located below the centrifugal separator.

[0009] In view of the problem of poor separation effect of the gas-liquid separator in the prior art when the gas content in the drilling fluid is high, the application provides a vertical drilling fluid gas-liquid separator, the main body of the separator is a tank body, the drilling fluid returned from the wellhead enters the inside of the tank body from the fluid inlet channel, the separated drilling fluid is discharged from the tank body through the drilling fluid outlet channel, and the separated gas is discharged from the tank body through the exhaust port.

[0010] The centrifugal separator comprises a cylinder body, an exhaust pipe located at the top of the cylinder body and a liquid outlet pipe located at the bottom of the cylinder body, a plurality of annular support rods are arranged at the bottom end of the inside of the cylinder body, the top end of the support rods is connected with a cyclone stabilizing disc, the cyclone stabilizing disc is coaxial with the liquid outlet pipe, and the diameter of the cyclone stabilizing disc is greater than the inner diameter of the liquid outlet pipe.

[0011] The mixed drilling fluid carrying solid phase and gas phase enters the cylinder body of the centrifugal separator through the fluid inlet channel, and does centrifugal motion in the cylinder body under the action of inertia, thereby being beneficial to separating the mixed gas in the mixed drilling fluid and making the separated gas discharged upwards from the exhaust pipe at the top to the tank body space outside the cylinder body, and the remaining liquid and solid are discharged from the liquid outlet pipe at the bottom of the cylinder body to the tank body space outside the cylinder body.

[0012] In the working condition of high gas content in the drilling fluid faced by the present application, the amount of gas to be treated can be relatively large, and the gas phase distribution in the cylinder is prone to disorder and the gas core is prone to unstable rotation during centrifugal separation, which leads to the continuous splitting of bubbles and the escape of bubbles from the liquid discharge pipe, seriously affecting the separation efficiency of the centrifugal separator. In order to overcome this problem, the cyclone stabilizing disc is arranged above the liquid discharge pipe, and the diameter of the cyclone stabilizing disc is greater than the inner diameter of the liquid discharge pipe. Through the arrangement of the cyclone stabilizing disc, the rotational flow field stability of the fluid in the cylinder can be significantly improved, and the uniformity of the velocity field distribution can be improved, thereby improving the rotational stability in the cylinder, which is beneficial to the aggregation of bubbles in the mixed fluid and the formation of a stable rotating gas core, thereby reducing the possibility of gas phase extending to the liquid discharge pipe and escaping. Moreover, due to the significant improvement of the gas core stability in the present scheme, the gas-liquid two-phase in the cylinder can form a clear interface, so that the liquid phase and the gas phase are not easy to be entrained with each other, and the gas-liquid separation effect is significantly improved.

[0013] Further, the centrifugal separator further comprises an inlet pipe connected with the fluid inlet channel, and the axis of the inlet pipe is perpendicular to and does not intersect with the axis of the cylinder.

[0014] In the present scheme, the returned drilling fluid after the fluid inlet channel enters the centrifugal separator through the inlet pipe. The axis of the inlet pipe is perpendicular to and does not intersect with the axis of the cylinder, that is, the axes of the two are staggered and perpendicular in space. This arrangement makes the inlet pipe eccentrically arranged compared with the cylinder in the cross section, and the fluid entering the cylinder rotates tangentially along the cylinder wall under the action of inertia. Under the dual action of centrifugal force and gravity, due to the different densities of gas phase and liquid phase, gas and liquid will be stratified in the cylinder, and a liquid film will be formed on the cylinder wall. The gas phase is gathered to form a rotating gas core and floats up and overflows through the gas discharge pipe. The present scheme is beneficial to improving the gas-liquid separation effect in the centrifugal separator.

[0015] Further, the fluid inlet channel comprises a fluid inlet pipe and an inner pipe coaxially fixed inside the fluid inlet pipe; the outer wall of the inner pipe is fixed with a spiral blade, and a plurality of first through holes are formed on the surface of the inner pipe; along the fluid flow direction, one end of the inner pipe close to the tank body is open, and the other end of the inner pipe away from the tank body is closed.

[0016] When the gas content is high, the traditional fluid inlet channel is prone to vibration, and when the flow rate is large, it can even cause the tank to vibrate obviously, which is not conducive to the safety and stability of the operation. The inventor found that the reason for the above phenomenon is that when the drilling fluid flows upward, the pressure gradually decreases, the gas in it expands continuously, and small gas bubbles collide and aggregate to form large gas bubbles; until the bubble diameter is close to the pipe diameter, at this time the bubble occupies most of the pipe cross section, forming a liquid-gas slug flow. The gas slug is shaped like a bullet, which also carries liquid particles; between the two gas segments, there is a liquid (containing solid) segment with small gas bubbles flowing upward. The effect of the bullet-shaped bubble lifting the liquid can be equivalent to a broken piston pushing upward; while the slug moves upward, the liquid layer between the bullet-shaped bubble and the pipe wall also flows relatively. Under this flow pattern, the relative motion between the liquid and gas phases is smaller than that of the bubble flow, the slip effect is also small, which leads to the instability of the fluid and the vibration of the pipe wall.

[0017] To overcome the above problems, the fluid inlet channel of the present application is provided with a double-layer pipe structure, including an inner pipe and a fluid inlet pipe coaxially distributed inside and outside, and a spiral blade is arranged on the outer wall of the inner pipe, thereby forming a spiral flow channel in the annulus between the inner pipe and the fluid inlet pipe. After the drilling fluid enters the fluid inlet pipe, it flows in the annulus along the spiral flow channel, is forced to do centrifugal motion, and generates uniform extrusion force on the inner wall of the fluid inlet pipe in all directions, thereby significantly reducing the pipe wall vibration through the balance of the forces in all directions, ensuring the stability of the fluid inlet pipe and the tank; at the same time, due to the restriction of the spiral flow direction, the generation of slug flow is significantly reduced, which can further reduce the vibration risk of the pipeline and improve the service life of the fluid inlet channel and the tank.

[0018] In addition, due to the density difference between the gas phase and the solid-liquid phase, when the drilling fluid rotates around the spiral blade, a pressure gradient will naturally occur in the fluid, and the liquid and solid will tend to move radially outward, and the gas in the process will be squeezed radially inward; and because the inner pipe surface is provided with a plurality of first through holes, the gas that moves radially inward can enter the inner pipe through the first through holes and finally be discharged from the top end of the inner pipe. Therefore, the present application not only can effectively reduce the vibration of the fluid inlet channel, but also can pretreat the drilling fluid about to enter the tank and pre-separate the gas therein, so that the fluid entering the centrifugal separator has been subjected to primary degassing treatment, effectively reducing the working pressure of the centrifugal separator and improving the overall separation effect of the present application.

[0019] Further, the axis of the fluid inlet pipe is parallel to the axis of the tank; the top end of the inner pipe is open, the bottom end is closed, and a flow guide cap is arranged at the bottom end of the inner pipe;

[0020] The top end of the fluid inlet pipe is connected to a T-shaped joint, the top end of the T-shaped joint is closed, and the other end is used to communicate with the centrifugal separator;

[0021] The bottom end of the fluid inlet pipe is connected to a cross joint, and the bottom end of the cross joint is connected to a first drain valve; of the other two ends of the cross joint, one end is closed and the other end is used for drilling fluid entry.

[0022] Since this application pertains to a vertical drilling fluid gas-liquid separator, with the tank axis vertically distributed, both the fluid inlet pipe and the inner pipe are vertically distributed. The bottom end of the inner pipe is sealed by a flow guide cap. The drilling fluid enters from the bottom end of the fluid inlet pipe, is guided and diverted by the flow guide cap, and then enters the spiral blades in the annulus. The presence of the flow guide cap can mitigate the erosion and impact of the drilling fluid on the bottom end of the inner pipe, which is beneficial to the stability of the inner pipe and reduces the risk of vibration.

[0023] Furthermore, in existing technologies, due to the high flow velocity of the returned mud, the solid particles carried in the mud continuously impact the pipe wall, easily causing erosion and even puncture leaks at bends. This solution, however, reduces the erosion of the fluid inlet pipe by using T-joints and cross-joints. Specifically: In the three joints of the T-joint, the bottom connects to the top of the inner pipe, the side connects to the centrifuge, and the top is directly opposite the connection to the inner pipe and is closed. The drilling fluid does not directly enter the centrifuge direction through the bend, but rather enters the centrifuge direction at the top of the T-joint in a vortex manner. In the four joints of the cross-joint, the top connects to the fluid inlet pipe, the bottom connects to the first drain valve, and of the remaining two side ends, one is used for drilling fluid entry, while the other is closed. Therefore, the drilling fluid entering the cross-joint does not directly enter the fluid inlet pipe through the bend, but rather enters the fluid inlet pipe within the cross-joint in a vortex manner.

[0024] This solution can significantly reduce the erosion of the fluid inlet channel by the drilling fluid, extending its service life and operational stability. Furthermore, the first drain valve can be controlled manually or electrically, facilitating regular draining and preventing blockages caused by the accumulation of solid deposits in the drilling fluid or pipeline freezing.

[0025] Furthermore, the baffle assembly includes a plurality of baffles arranged alternately on opposite sides of the inner wall of the tank, the baffles being wavy; and the baffles gradually slope downward from one end near the inner wall of the tank to the end away from the inner wall of the tank.

[0026] This design uses several baffles arranged alternately on opposite sides of the tank's inner wall, allowing the liquid after passing through the centrifugal separator to flow downwards sequentially through the surfaces of each baffle. The inclined arrangement of the baffles facilitates the layer-by-layer flow of the drilling fluid. Larger bubbles will break up on the baffle surfaces, detach from the mud, and form an air film on the mud surface. Through repeated deflection and bubble breaking by multiple layers of baffles, the purpose of mud degassing is achieved.

[0027] Furthermore, this solution creatively employs a wave-shaped baffle. When the fluid flows on the surface of the baffle, it undulates along the wave-shaped surface to form a wave-like flow. From the perspective of flow pattern, the fluid exhibits a separated flow on the surface of the baffle (a phenomenon where the boundary layer's velocity relative to the object drops to almost zero when it travels a sufficient distance relative to the adverse pressure gradient, resulting in flow separation). Under this condition, the gas and liquid phases easily form a distinct phase interface. Due to the velocity difference between the two phases at the phase interface, relative friction is generated between the gas and liquid phases, which in turn creates turbulent waves at the phase interface. The phase interface becomes constantly fluctuating due to the waves moving along the flow direction, thus forming a wave-like flow pattern both macroscopically and microscopically. This is more conducive to gas-liquid separation and improves the degassing capacity of the baffle assembly.

[0028] Furthermore, a baffle assembly is fixedly connected to the inner wall of the tank. The inner wall of the baffle assembly is provided with a guide groove and a mounting protrusion. The mounting protrusion is provided with a plurality of first threaded holes evenly distributed along the longitudinal direction.

[0029] The end plate near the inner wall of the tank is fixedly connected to the baffle plate. The end plate is provided with a sliding part that matches the guide groove and a convex part that matches the mounting protrusion. The opposite side walls of the convex part are provided with a plurality of second threaded holes evenly distributed in the longitudinal direction. The second threaded holes match the first threaded holes.

[0030] In this design, each baffle plate is connected to an end plate, enabling detachable connection between the baffle plate assembly and the end plate, and allowing for longitudinal sliding. This facilitates flexible adjustment of the height of each baffle plate and the spacing between adjacent baffle plates. In practical use, the convex part is fitted over the mounting protrusion, the sliding part enters the corresponding guide groove, each baffle plate is adjusted to a suitable height, the second threaded hole is aligned with the first threaded hole, and then connected with bolts.

[0031] Furthermore, the outer wall of the baffle assembly is provided with a longitudinally extending air guide channel, both the upper and lower ends of which are open; the baffle assembly is also provided with a plurality of second through holes, one end of which is located on the inner surface of the baffle assembly, and the other end of which is connected to the air guide channel.

[0032] During further research, the inventors discovered that due to the inclined arrangement of the baffles, an acute angle is formed between the bottom surface of the baffle and the baffle assembly. This causes some of the gas escaping from the area below a certain baffle to accumulate in the area between the bottom surface of the baffle and the baffle assembly during its upward movement. The gas in this area is difficult to flow upward and dissipate, accumulating inside the tank for a long time. This is not conducive to the full exhaust of the tank and can easily bring significant safety hazards to the maintenance and repair of the gas-liquid separator. In particular, the corrugated baffles used in this application exacerbate this phenomenon due to the corrugations at the bottom.

[0033] To overcome this problem, this method incorporates a longitudinally extending gas guiding channel on the outer wall of the baffle assembly. This channel is fully longitudinally open and has several second through-holes connecting it to the interior of the tank. When gas accumulates between the bottom surface of the baffle and the baffle assembly, preventing upward flow, it enters through the second through-holes and then into the gas guiding channel, ultimately exiting from the top of the channel. This solution effectively avoids gas accumulation and retention inside the tank due to the structure and arrangement of the baffles, significantly improving the tank's exhaust capacity and operational safety during gas-liquid separator maintenance.

[0034] It should be noted that, in this application, the inner wall of the baffle assembly refers to the side wall facing the central area inside the tank, that is, the side wall facing radially inward; conversely, the outer wall of the baffle assembly refers to the side wall away from the central area inside the tank, that is, the side wall facing radially outward.

[0035] Furthermore, the drilling fluid discharge channel includes a discharge outlet disposed on the side wall of the tank and a first discharge pipe coaxial with and connected to the discharge outlet; a filter plate is disposed at one end of the discharge outlet connected to the inside of the tank, and a reduced-diameter liner is disposed inside the discharge outlet, with the large-diameter end of the reduced-diameter liner connected to the filter plate and the small-diameter end extending into the inside of the first discharge pipe.

[0036] After degassing, the drilling fluid accumulates at the bottom of the tank. When the fluid level reaches the outlet height, it is filtered through the filter plate and discharged downstream through the reduced-diameter liner pipe inside the outlet. The outlet is located on the side wall of the tank, so the area at the bottom of the tank below the outlet can be used as a sedimentation zone. The filter plate filters large solid particles, preventing them from clogging the reduced-diameter liner pipe and its downstream pipes. Due to the gradually changing inner diameter of the reduced-diameter liner pipe, the fluid velocity gradually increases upon entering it, providing a faster initial velocity for the fluid entering the first discharge pipe. This facilitates smoother drainage to the downstream solids control system and also promotes subsequent gas return through the first discharge pipe.

[0037] Furthermore, the end face of the first discharge pipe away from the discharge outlet is closed, and the bottom of the end of the first discharge pipe away from the discharge outlet is connected to a second discharge pipe;

[0038] The inner wall of the first discharge pipe is provided with a plurality of first baffles and second baffles arranged alternately at the upper and lower ends; the first baffles are inclined from top to bottom in the direction away from the discharge outlet; the second baffles are inclined from bottom to top in the direction away from the discharge outlet.

[0039] Between any two adjacent first baffle plates, there is a first bypass pipe opened at the top of the first discharge pipe; all first bypass pipes are connected to the return gas pipe, the return gas pipe is connected to the inside of the tank, and the height of the position where the return gas pipe is connected to the tank is greater than or equal to the height of the centrifugal separator.

[0040] Between any two adjacent second baffles, there is a second bypass pipe located at the bottom of the first discharge pipe; all second bypass pipes are connected to the second discharge pipe.

[0041] In this design, a transverse flow channel is formed by several first and second baffles. The fluid ejected at high speed through the narrow-diameter inner liner tube flows up and down between the first and second baffles, which promotes the formation of the gas-liquid interface and further separates the gas remaining in the drilling fluid. Since the fluid flows laterally in the first discharge pipe, gravity has a more significant effect on the separation of the gas and liquid phases. The separated gas gathers in the top area between two adjacent first baffles, enters the return gas pipe through the first bypass pipe, and finally returns to the tank and is discharged from the exhaust port. In addition, the fluid ejected at high speed from the narrow-diameter inner liner tube slows down suddenly after entering the first discharge pipe, which also facilitates the rapid stratification of the gas and liquid phases.

[0042] Furthermore, the fluid entering the first discharge pipe still contains a large number of small solid rock cuttings and impurities. Due to the presence of several second baffles, these particles and impurities are prone to accumulate in the first discharge pipe, leading to a reduction in the flow diameter or even blockage. Therefore, this solution also opens a second bypass pipe between any two adjacent second baffles, so that the rock cuttings or impurities accumulated between adjacent second baffles can directly enter the second discharge pipe without unnecessary bypassing, which significantly improves the stability of this application in the drilling fluid discharge process and provides sufficient guarantee for the discharge efficiency of this application.

[0043] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0044] 1. This invention provides a vertical drilling fluid gas-liquid separator and a gas-liquid separation method. The drilling fluid entering the tank moves from top to bottom. During the movement, it passes through a centrifugal separator and a baffle assembly in sequence. Through the combined action of the centrifugal separator and the baffle assembly, the gas and liquid phases are separated, and the return drilling fluid is efficiently degassed, thereby improving the gas-liquid separation effect of drilling fluid with high gas content.

[0045] 2. This invention can significantly improve the stability of the swirling flow field of the fluid undergoing centrifugal motion inside the cylinder and improve the uniformity of the velocity field distribution, thereby improving the swirling stability inside the cylinder. This is beneficial for the aggregation of bubbles in the mixed fluid and for the formation of stable rotating gas nuclei, thereby reducing the possibility of the gas phase extending to the drain pipe and escaping. Due to the significantly improved stability of the gas nuclei, a clear interface can also be formed between the gas and liquid phases inside the cylinder, making it less likely for the liquid and gas phases to entrain each other, thus significantly improving the gas-liquid separation effect.

[0046] 3. This invention can significantly reduce pipe wall vibration, ensuring the stability of fluid entering the pipe and tank; at the same time, it significantly reduces the generation of slug flow, further reducing the vibration risk of the pipeline and improving the service life of the fluid entry channel and tank.

[0047] 4. This invention can not only effectively reduce the vibration of the fluid entering the channel, but also pre-treat the drilling fluid that is about to enter the tank and pre-separate the gas in it, so that the fluid entering the centrifugal separator has undergone the initial degassing treatment, effectively reducing the working pressure of the centrifugal separator and improving the overall separation effect of this application.

[0048] 5. This invention can significantly reduce the erosion of the fluid inlet channel by drilling fluid, extend the service life and operational stability of the fluid inlet channel, and facilitate regular drainage, avoiding blockages caused by the accumulation of solid sediments in the drilling fluid or pipeline freezing.

[0049] 6. The baffle assembly of the present invention forms a wavy flow pattern in both the macroscopic and microscopic dimensions, which is more conducive to gas-liquid separation and improves the degassing capacity of the baffle assembly.

[0050] 7. This invention can avoid the accumulation and retention of gas inside the tank due to the structure and arrangement of the baffles, significantly improve the exhaust capacity inside the tank, and significantly improve the operational safety during the maintenance of the gas-liquid separator.

[0051] 8. This invention can significantly improve the stability of drilling fluid during the discharge process, and at the same time, it can perform gas-liquid separation again during the discharge process, further improving the degassing quality. Attached Figure Description

[0052] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0053] Figure 1 This is a front view of a specific embodiment of the present invention;

[0054] Figure 2 This is an isometric view of a specific embodiment of the present invention;

[0055] Figure 3 This is a cross-sectional view of a specific embodiment of the present invention;

[0056] Figure 4 This is a schematic diagram of a centrifugal separator in a specific embodiment of the present invention;

[0057] Figure 5 This is a schematic diagram of a half-section of the centrifugal separator in a specific embodiment of the present invention;

[0058] Figure 6 This is a half-section diagram of the fluid inlet channel in a specific embodiment of the present invention;

[0059] Figure 7 This is a schematic diagram of the deflector component in a specific embodiment of the present invention;

[0060] Figure 8 for Figure 7 A magnified view of a section at point A in the middle;

[0061] Figure 9 This is a partial schematic diagram of the baffle assembly in a specific embodiment of the present invention;

[0062] Figure 10 This is a half-section structural diagram of the drilling fluid discharge channel in a specific embodiment of the present invention;

[0063] Figure 11 This is a schematic diagram of the structure of the deflector umbrella in a specific embodiment of the present invention;

[0064] Figure 12 This is a schematic diagram of the air guide groove in a specific embodiment of the present invention.

[0065] The attached diagram shows the markings and corresponding component names:

[0066] 1-Tank body, 2-Exhaust port, 3-Centrifugal separator, 301-Cylinder body, 302-Exhaust pipe, 303-Drain pipe, 304-Swirl stabilizer, 305-Inlet pipe, 306-Support rod, 4-Fluid inlet channel, 401-Fluid inlet pipe, 402-Inner pipe, 403-Helical blade, 404-First through hole, 405-T-connector, 406-Cross connector, 407-Flow guide cap, 408-First drain valve, 5-Drilling fluid discharge channel, 501-Discharge outlet, 502-First discharge pipe, 503-Filter plate, 504-Reduced diameter inner liner, 50 5-Second discharge pipe, 506-First baffle, 507-Second baffle, 508-First bypass pipe, 509-Return pipe, 510-Second bypass pipe, 6-Baffle plate, 7-Baffle plate assembly, 8-Guide groove, 9-Mounting protrusion, 10-First threaded hole, 11-End plate, 12-Sliding part, 13-Convex part, 14-Second threaded hole, 15-Air guide channel, 16-Second through hole, 17-Safety valve, 18-Manhole, 19-Second drain valve, 20-Baffle umbrella, 201-Umbrella rim, 202-Mounting hole, 203-Umbrella hole, 21-Air guide groove. Detailed Implementation

[0067] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and accompanying drawings. The illustrative embodiments and descriptions of this invention are for explaining the invention only and are not intended to limit the invention. In the description of this application, it should be understood that terms such as "front," "rear," "left," "right," "upper," "lower," "vertical," "horizontal," "high," "low," "inner," and "outer," indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the scope of protection of this application.

[0068] Example 1:

[0069] like Figures 1 to 5 A vertical drilling fluid gas-liquid separator is shown, comprising a tank 1, a fluid inlet channel 4, a drilling fluid outlet channel 5, and an exhaust port 2 connected to the interior of the tank 1. The exhaust port 2 is located at the top of the tank 1, and the fluid inlet channel 4 is higher than the drilling fluid outlet channel 5. A centrifugal separator 3 and a baffle assembly are provided inside the tank 1. The centrifugal separator 3 is connected to the fluid inlet channel 4, and the baffle assembly is located below the centrifugal separator 3.

[0070] The centrifugal separator 3 includes a cylinder 301, an exhaust pipe 302 located at the top of the cylinder 301, and a drain pipe 303 located at the bottom of the cylinder 301. Several annularly distributed support rods 306 are provided at the bottom of the inside of the cylinder 301. The top of the support rods 306 is connected to a vortex stabilizing disk 304. The vortex stabilizing disk 304 is coaxial with the drain pipe 303, and the diameter of the vortex stabilizing disk 304 is larger than the inner diameter of the drain pipe 303.

[0071] The centrifugal separator 3 also includes an inlet pipe 305 for connecting to the fluid inlet channel 4. The axis of the inlet pipe 305 is perpendicular to and does not intersect with the axis of the cylinder 301; that is, the inlet pipe 305 is eccentrically distributed relative to the cylinder 301.

[0072] To assess the effectiveness of the swirl stabilizing disk 304 in this embodiment, the inventors conducted a simulation. The simulated pressure and tangential velocity cloud diagrams show that with the swirl stabilizing disk 304, the cyclone region in the middle of the cylinder 301 is quite stable, the air column is stably connected vertically, and the velocity field is uniformly distributed, resulting in a stable swirling process. This is beneficial for the aggregation of bubbles in the mixture to form a stable rotating gas nucleus. Without the swirl stabilizing disk 304, this effect is clearly not achieved.

[0073] In this embodiment, a safety valve 17 is provided on the tank body 1, a manhole 18 for maintenance is provided on the side of the tank body 1, and a second drain valve 19 is provided at the bottom of the tank body 1.

[0074] Considering that traditional drilling fluid gas-liquid separators are one-piece structures, with the entire separator shell and internal structure welded together and only having a manhole on the surface, they are inconvenient for inspection and replacement; at the same time, existing separators are large in size and heavy, making them inconvenient for transportation, installation and maintenance. Therefore, in this embodiment, the tank 1 is divided into several parts along the longitudinal direction, and adjacent parts are connected by flange sealing to facilitate replacement and maintenance.

[0075] In addition, the inlet pipe 305 is also connected to the fluid inlet channel 4 by a flange seal.

[0076] Preferably, the inlet pipe 305 has a rectangular or semi-circular cross-section. Numerical simulation experiments conducted by the inventors have verified that inlet pipes with rectangular or semi-circular cross-sections exhibit better gas-liquid separation performance than conventional circular structures. Alternatively, a spiral inlet pipe can be used to enhance the stratification of the gas and liquid phases within the inlet pipe 305, thereby improving separation efficiency.

[0077] Preferred, such as Figure 3 As shown, a baffle 20 is also provided inside the tank body 1, and the baffle 20 is located above the exhaust pipe 302 of the centrifugal separator 3. The baffle 20 has a cone-shaped structure that is larger at the bottom and smaller at the top, and is used to capture droplets carried in the rising airflow, and also plays a role in stabilizing the upper cyclone and guiding the rising airflow.

[0078] In a more preferred embodiment, such as Figure 11 As shown, the bottom end of the deflector umbrella 20 is provided with an umbrella rim 201, and a plurality of mounting holes 202 are evenly distributed in a ring on the umbrella rim 201. The top end of the deflector umbrella 20 has an umbrella hole 203 for airflow passage. A ring of mounting bosses is provided on the inner side wall of the tank body 1 for cooperating with the umbrella rim 201, so that the umbrella rim 201 sits on the mounting bosses. Threaded holes corresponding one-to-one with the mounting holes 202 are provided on the mounting bosses, and the umbrella rim 201 is connected to the mounting bosses by bolts.

[0079] Example 2:

[0080] A vertical drilling fluid gas-liquid separator, based on Example 1, such as... Figures 1 to 6 As shown, the fluid inlet channel 4 includes a fluid inlet pipe 401 and an inner pipe 402 coaxially fixed inside the fluid inlet pipe 401; a spiral blade 403 is fixed on the outer wall of the inner pipe 402, and a plurality of first through holes 404 are opened on the surface of the inner pipe 402; along the fluid flow direction, the end of the inner pipe 402 near the tank 1 is open, and the end of the inner pipe 402 away from the tank 1 is closed.

[0081] The axis of the fluid inlet pipe 401 is parallel to the axis of the tank body 1; the inner pipe 402 is open at the top and closed at the bottom, and a flow guide cap 407 is provided at the bottom of the inner pipe 402;

[0082] The top end of the fluid inlet pipe 401 is connected to a T-connector 405, the top end of which is closed and the other end is used to communicate with the centrifugal separator 3;

[0083] The bottom end of the fluid inlet pipe 401 is connected to a cross joint 406, and the bottom end of the cross joint 406 is connected to a first drain valve 408; of the other two ends of the cross joint 406, one end is closed and the other end is used for drilling fluid entry.

[0084] In this embodiment, the size of the helical blade 403 matches that of the fluid inlet pipe 401; that is, on a cross section perpendicular to the axis of the fluid inlet pipe 401, the projection of the helical blade 403 exactly fills the fluid inlet pipe 401.

[0085] In this embodiment, the diameter of the first through hole 404 is preferably in the millimeter range.

[0086] In this embodiment, both the first drain valve 408 and the second drain valve 19 are preferably electric butterfly valves.

[0087] Example 3:

[0088] A vertical drilling fluid gas-liquid separator, based on Example 1 or 2, such as... Figures 1 to 9As shown, the baffle assembly includes several baffle plates 6 arranged alternately on opposite sides of the inner wall of the tank 1. The baffle plates 6 are wavy and gradually slope downward from the end closest to the inner wall of the tank 1 to the end furthest from the inner wall of the tank 1.

[0089] The inner wall of the tank body 1 is fixedly connected to the baffle assembly 7. The inner wall of the baffle assembly 7 is provided with a guide groove 8 and a mounting protrusion 9. The mounting protrusion 9 is provided with a plurality of first threaded holes 10 evenly distributed along the longitudinal direction.

[0090] The end plate 11 is fixedly connected to one end of the baffle plate 6 near the inner wall of the tank body 1. The end plate 11 is provided with a sliding part 12 that matches the guide groove 8 and a convex part 13 that matches the mounting protrusion 9. The two opposite side walls of the convex part 13 are provided with a plurality of second threaded holes 14 evenly distributed in the longitudinal direction. The second threaded holes 14 match the first threaded holes 10.

[0091] To address the potential issue of gas accumulation below baffle 6, this embodiment provides the following two solutions, which can be used individually or simultaneously:

[0092] Method 1:

[0093] like Figure 7 and Figure 8 As shown, a longitudinally extending air guide channel 15 is provided on the outer wall of the baffle assembly 7, and both the upper and lower ends of the air guide channel 15 are open; a plurality of second through holes 16 are also provided on the baffle assembly 7, one end of the second through hole 16 is located on the inner surface of the baffle assembly 7, and the other end of the second through hole 16 is connected to the air guide channel 15.

[0094] Method 2:

[0095] like Figure 12 As shown, several air guide grooves 21 are provided on the inner wall of the baffle assembly 7, and the upper and lower ends of the air guide grooves 21 pass through the baffle assembly 7. Preferably, the inner wall of the baffle assembly 7 has two guide grooves 8, and an air guide groove 21 is provided next to each guide groove 8. The air guide grooves 21 and the guide grooves 8 are parallel to each other.

[0096] Preferably, the angle between the extension direction of the baffle 6 and the horizontal plane is 8° to 30°. The extension direction of the baffle 6 can be understood as the line connecting the end of the baffle 6 closest to the inner wall of the tank 1 and the end furthest from the inner wall of the tank 1.

[0097] In a more preferred embodiment, the guide groove 8 has an anti-detachment groove type, such as a dovetail groove or a T-shaped groove.

[0098] In a more preferred embodiment, the back of the baffle assembly 7, i.e. the radially outward sidewall, is an outwardly convex arc surface.

[0099] Example 4:

[0100] A vertical drilling fluid gas-liquid separator, based on any of the above embodiments, such as... Figures 1 to 10 As shown, the drilling fluid discharge channel 5 includes a discharge outlet 501 disposed on the side wall of the tank body 1 and a first discharge pipe 502 coaxial with and connected to the discharge outlet 501; a filter plate 503 is disposed at one end of the discharge outlet 501 connected to the inside of the tank body 1, and a reduced diameter liner 504 is disposed inside the discharge outlet 501, with the large diameter end of the reduced diameter liner 504 connected to the filter plate 503 and the small diameter end extending into the inside of the first discharge pipe 502.

[0101] The end face of the first discharge pipe 502 away from the discharge port 501 is closed, and the bottom of the end of the first discharge pipe 502 away from the discharge port 501 is connected to the second discharge pipe 505.

[0102] The inner wall of the first discharge pipe 502 is provided with a plurality of first baffles 506 and second baffles 507 arranged alternately at the upper and lower ends; the first baffles 506 are inclined from top to bottom in a direction away from the discharge outlet 501; the second baffles 507 are inclined from bottom to top in a direction away from the discharge outlet 501.

[0103] Between any two adjacent first baffle plates 506, there is a first bypass pipe 508 opened at the top of the first discharge pipe 502; all first bypass pipes 508 are connected to the return pipe 509, the return pipe 509 is connected to the inside of the tank 1, and the position where the return pipe 509 is connected to the tank 1 is located above the centrifugal separator 3 and below the baffle umbrella 20.

[0104] Between any two adjacent second baffles 507, there is a second bypass pipe 510 opened at the bottom of the first discharge pipe 502; all second bypass pipes 510 are connected to the second discharge pipe 505.

[0105] In this embodiment, the outlet 501 is located at a low position on the side wall of the tank 1, and there is a gap between the outlet 501 and the bottom of the tank 1. When the tank 1 is placed on a horizontal surface, the axis of the first discharge pipe 502 is horizontal and the axis of the second discharge pipe 505 is vertical.

[0106] Preferably, the inner diameter of the first discharge pipe 502 is larger than the inner diameter of the small diameter end of the reduced-diameter liner pipe 504, and also larger than the inner diameter of the second discharge pipe 505.

[0107] More preferably, the angle between the first baffle 506, the second baffle 507 and the vertical plane is 30°~45°.

[0108] Example 5:

[0109] A drilling fluid gas-liquid separation method, implemented based on the vertical drilling fluid gas-liquid separator in any of the above embodiments, includes:

[0110] S1. Drilling fluid returning from the wellhead enters fluid inlet channel 4, where the first gas-liquid separation takes place.

[0111] S2. The drilling fluid discharged from the fluid inlet channel 4 enters the centrifugal separator 3 through the inlet pipe 305, where a second gas-liquid separation is carried out.

[0112] S3. The drilling fluid discharged from the drain pipe 303 at the bottom of the centrifugal separator 3 passes through the baffle assembly from top to bottom and undergoes a third gas-liquid separation by the baffle assembly.

[0113] S4. The drilling fluid that has accumulated at the bottom of tank 1 enters the drilling fluid discharge channel 5 and undergoes a fourth gas-liquid separation in the drilling fluid discharge channel 5.

[0114] As can be seen, this embodiment can perform four consecutive gas-liquid separations, which significantly reduces the gas content in the drilling fluid after it flows through the gas-liquid separator. It can significantly improve the separation ability of the gas phase in the drilling fluid, and is especially suitable for use when the gas content in the drilling fluid is high.

[0115] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0116] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Additionally, the term "connection" as used herein, unless otherwise specified, can refer to a direct connection or an indirect connection via other components.

Claims

1. A vertical drilling fluid gas-liquid separator, comprising a tank (1), a fluid inlet channel (4) communicating with the interior of the tank (1), a drilling fluid outlet channel (5), and an exhaust port (2), wherein the exhaust port (2) is located at the top of the tank (1), characterized in that, The fluid inlet channel (4) is higher than the drilling fluid outlet channel (5). The tank body (1) is equipped with a centrifugal separator (3) and a baffle assembly. The centrifugal separator (3) is connected to the fluid inlet channel (4), and the baffle assembly is located below the centrifugal separator (3). The centrifugal separator (3) includes a cylinder (301), an exhaust pipe (302) at the top of the cylinder (301), and a drain pipe (303) at the bottom of the cylinder (301). Several annularly distributed support rods (306) are provided at the bottom of the inside of the cylinder (301). The top of the support rods (306) is connected to a swirling stabilizer (304). The swirling stabilizer (304) is coaxial with the drain pipe (303), and the diameter of the swirling stabilizer (304) is larger than the inner diameter of the drain pipe (303). The baffle assembly includes several baffle plates (6) arranged alternately on opposite sides of the inner wall of the tank (1), the baffle plates (6) being wavy; and the baffle plates (6) gradually tilt downward from one end close to the inner wall of the tank (1) to the other end away from the inner wall of the tank (1); The inner wall of the tank (1) is fixedly connected to the baffle assembly (7). The inner wall of the baffle assembly (7) is provided with a guide groove (8) and a mounting protrusion (9). The mounting protrusion (9) is provided with a plurality of first threaded holes (10) evenly distributed along the longitudinal direction. The baffle (6) is fixedly connected to an end plate (11) at one end near the inner wall of the tank (1). The end plate (11) is provided with a sliding part (12) that matches the guide groove (8) and a convex part (13) that matches the mounting protrusion (9). The opposite side walls of the convex part (13) are provided with a plurality of second threaded holes (14) evenly distributed in the longitudinal direction. The second threaded holes (14) match the first threaded holes (10). The outer wall of the baffle assembly (7) is provided with a longitudinally extending air guide channel (15), and both the upper and lower ends of the air guide channel (15) are open; the baffle assembly (7) is also provided with a number of second through holes (16), one end of the second through hole (16) is located on the inner surface of the baffle assembly (7), and the other end of the second through hole (16) is connected to the air guide channel (15).

2. A vertical drilling fluid gas-liquid separator according to claim 1, characterized in that, The centrifugal separator (3) also includes an inlet pipe (305) for connection to the fluid inlet channel (4), the axis of which is perpendicular to and does not intersect with the axis of the cylinder (301).

3. A vertical drilling fluid gas-liquid separator according to claim 1, characterized in that, The fluid inlet channel (4) includes a fluid inlet pipe (401) and an inner pipe (402) coaxially fixed inside the fluid inlet pipe (401); a spiral blade (403) is fixed on the outer wall of the inner pipe (402), and a plurality of first through holes (404) are opened on the surface of the inner pipe (402); along the fluid flow direction, the end of the inner pipe (402) close to the tank (1) is open, and the end of the inner pipe (402) away from the tank (1) is closed.

4. A vertical drilling fluid gas-liquid separator according to claim 3, characterized in that, The axis of the fluid inlet pipe (401) is parallel to the axis of the tank body (1); the inner pipe (402) is open at the top and closed at the bottom, and a flow guide cap (407) is provided at the bottom of the inner pipe (402). The top end of the fluid inlet pipe (401) is connected to a T-connector (405), the top end of which is closed and the other end is used to communicate with the centrifuge (3); The bottom end of the fluid inlet pipe (401) is connected to a cross joint (406), and the bottom end of the cross joint (406) is connected to a first drain valve (408); of the other two ends of the cross joint (406), one end is closed and the other end is used for drilling fluid entry.

5. A vertical drilling fluid gas-liquid separator according to claim 1, characterized in that, The drilling fluid discharge channel (5) includes a discharge port (501) provided on the side wall of the tank (1) and a first discharge pipe (502) coaxial with and connected to the discharge port (501); a filter plate (503) is provided at one end of the discharge port (501) connected to the inside of the tank (1), and a reduced diameter liner (504) is provided inside the discharge port (501). The large diameter end of the reduced diameter liner (504) is connected to the filter plate (503), and the small diameter end extends into the inside of the first discharge pipe (502).

6. A vertical drilling fluid gas-liquid separator according to claim 5, characterized in that, The end face of the first discharge pipe (502) away from the discharge port (501) is closed, and the bottom of the end of the first discharge pipe (502) away from the discharge port (501) is connected to the second discharge pipe (505). The inner wall of the first discharge pipe (502) is provided with a plurality of first baffles (506) and second baffles (507) arranged alternately at the upper and lower ends; the first baffles (506) are inclined from top to bottom in a direction away from the discharge outlet (501); the second baffles (507) are inclined from bottom to top in a direction away from the discharge outlet (501); Between any two adjacent first baffle plates (506), there is a first bypass pipe (508) opened at the top of the first discharge pipe (502); all first bypass pipes (508) are connected to the return pipe (509), the return pipe (509) is connected to the inside of the tank (1), and the height of the position where the return pipe (509) is connected to the tank (1) is greater than or equal to the height of the centrifugal separator (3); Between any two adjacent second baffles (507), there is a second bypass pipe (510) opened at the bottom of the first discharge pipe (502); all second bypass pipes (510) are connected to the second discharge pipe (505).

7. A gas-liquid separation method based on any one of claims 1 to 6 of a vertical drilling fluid gas-liquid separator, comprising the following steps: S1. Drilling fluid returning from the wellhead enters the fluid inlet channel (4) and undergoes the first gas-liquid separation in the fluid inlet channel (4); S2. The drilling fluid discharged from the fluid inlet channel (4) enters the centrifugal separator (3) and undergoes a second gas-liquid separation in the centrifugal separator (3); S3. The drilling fluid discharged from the drain pipe (303) at the bottom of the centrifugal separator (3) passes through the baffle assembly from top to bottom and undergoes a third gas-liquid separation by the baffle assembly. S4. The drilling fluid that has accumulated at the bottom of the tank (1) enters the drilling fluid discharge channel (5) and undergoes a fourth gas-liquid separation in the drilling fluid discharge channel (5).

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