Vertical drilling fluid gas-liquid separator and gas-liquid separation method

Abstract

The invention discloses a vertical drilling fluid gas-liquid separator and a gas-liquid separation method, and relates to the field of gas-liquid separation of petroleum and natural gas development.The gas-liquid separator comprises a tank body, a fluid inlet channel communicated with the interior of the tank body, a drilling fluid outlet channel and an exhaust port, and the exhaust port is located in the top of the tank body; the fluid inlet channel is higher than the drilling fluid discharge channel, a centrifugal separator and a baffling assembly are arranged in the tank body, the centrifugal separator is communicated with the fluid inlet channel, and the baffling assembly is located below the centrifugal separator. According to the gas-liquid separation method developed based on the gas-liquid separator, four times of gas-liquid separation can be continuously carried out, then the gas phase separation capacity is remarkably improved, the problem that in the prior art, the gas-liquid separator is poor in separation effect when the gas content in drilling fluid is high is solved, and the gas-liquid separator is particularly suitable for being used 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, and after returning to the downhole operation, it cannot achieve the purpose of cooling and cleaning the drilling fluid, 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 stability of the cyclone flow field of the fluid in the cylinder doing centrifugal motion can be significantly improved, and the uniformity of the velocity field distribution is improved, thereby improving the cyclone 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 vertically 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 aggregated 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 spiral blades, 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 with a cross joint, the bottom end of the cross joint is connected with the first blowdown valve, one of the other two ends of the cross joint is closed, and the other end is used for drilling fluid to enter.

[0022] Since the present application is a vertical drilling fluid gas-liquid separator, the tank body axis is vertically distributed, so the fluid inlet pipe and the inner pipe are vertically distributed. The bottom end of the inner pipe is closed by a flow guide cap, drilling fluid enters from the bottom end of the fluid inlet pipe, is guided and divided by the flow guide cap, and then enters the spiral blades in the annular space. The presence of the flow guide cap can slow down the erosion and impact of drilling fluid on the bottom end of the inner pipe, which is conducive to the stability of the inner pipe and reduces the vibration risk of the inner pipe.

[0023] In addition, in the prior art, because the returning mud has a large flow rate, the solid particles carried in the mud will continuously impact the pipe wall, and erosion and even puncture leakage may occur at the elbow. However, the present application can reduce the erosion of drilling fluid on the fluid inlet pipe by using T-shaped joints and cross joints. Specifically, in the three joints of the T-shaped joint, the bottom end is connected with the top end of the inner pipe, the side end is connected with the centrifugal separator, and the top end is opposite to the connection end of the inner pipe and is in a closed state. Instead of directly entering the direction of the centrifugal separator through the elbow, the drilling fluid enters the direction of the centrifugal separator in a vortex manner at the top end of the T-shaped joint. In the four joints of the cross joint, the top end is connected with the fluid inlet pipe, the bottom end is connected with the first blowdown valve, and the remaining two side ends are closed. Therefore, the drilling fluid entering the cross joint will not directly enter the fluid inlet pipe through the elbow, but will enter the fluid inlet pipe in a vortex manner in the cross joint.

[0024] The present application can significantly reduce the erosion of drilling fluid on the fluid inlet passage, prolong the service life and working stability of the fluid inlet passage. In addition, the first blowdown valve can be manually or electrically controlled, which is convenient for regular blowdown and avoids blockage caused by accumulation of solid deposits in the drilling fluid or pipeline freezing.

[0025] Further, the baffle assembly includes a plurality of baffle plates arranged in an alternating manner on opposite sides of the inner wall of the tank body, and the baffle plates are in a wave shape and gradually inclined downward from one end close to the inner wall of the tank body to the other end away from the inner wall of the tank body.

[0026] The present application arranges a plurality of baffle plates in an alternating manner on opposite sides of the inner wall of the tank body, so that the liquid after the centrifugal separator flows downward in turn on the surface of each baffle plate. The inclined arrangement of the baffle plates is conducive to the layer-by-layer flow of the drilling fluid. The larger diameter gas bubbles will break and separate from the mud on the surface of the baffle plate and form a gas film on the surface of the mud. Through the repeated baffle breaking of the bubbles by the multiple baffle plates, the purpose of degassing the mud is achieved.

[0027] In addition, the present application creatively adopts the wave-shaped baffle plate, and the fluid fluctuates along the wave-shaped surface to form the wave flow when flowing on the surface of the baffle plate; from the flow pattern point of view, the fluid is in the separated flow on the surface of the baffle plate (a phenomenon that the speed of the boundary layer relative to the object almost drops to zero to cause the flow separation when the boundary layer travels far enough relative to the adverse pressure gradient), in this state, the gas-liquid two-phase is easy to form the obvious phase interface, and because of the speed difference between the two phases at the phase interface, the relative friction between the gas phase and the liquid phase is generated, and then the wave of disturbance is generated on the phase interface, the phase interface becomes undulating because of the wave moving along the flow direction, and thus the wave flow pattern is formed in the macro and micro, which is more beneficial to the separation of the gas-liquid and improves the degassing capacity of the baffle assembly.

[0028] Further, the inner wall of the baffle plate assembly is fixedly connected with the guide groove and the mounting protrusion, a plurality of first threaded holes distributed along the longitudinal direction are arranged on the mounting protrusion;

[0029] The end plate is fixedly connected with one end of the baffle plate close to the inner wall of the tank body, the sliding part matched with the guide groove and the convex part matched with the mounting protrusion are arranged on the end plate, a plurality of second threaded holes distributed along the longitudinal direction are arranged on the opposite two side walls of the convex part, and the second threaded holes are matched with the first threaded holes.

[0030] In the present application, each baffle plate is connected with an end plate, the detachable connection with the baffle plate assembly is realized through the end plate, the sliding along the longitudinal direction is realized, and then the height of each baffle plate and the spacing between the adjacent baffle plates are flexibly adjusted. In the specific use, the convex part is sleeved outside the mounting protrusion, the sliding part is arranged in the corresponding guide groove, each baffle plate is adjusted to the appropriate height, the second threaded holes are aligned with the first threaded holes, and the connection is realized through the bolts.

[0031] Further, the outer wall of the baffle plate assembly is provided with the longitudinally extending air guide channel, the upper and lower ends of the air guide channel are open, a plurality of second through holes are arranged on the baffle plate assembly, one end of the second through hole is located on the inner side surface of the baffle plate assembly, and the other end of the second through hole is communicated with the air guide channel.

[0032] The inventor has found in further research that due to the inclined arrangement of the baffle plates, an acute angle is formed between the bottom surface of the baffle plate and the baffle plate assembly, which causes part of the gas separated from the area below the baffle plate to gather in the area between the bottom surface of the baffle plate and the baffle plate assembly during upward flow, and the gas in this area is difficult to flow upward and is accumulated in the tank for a long time, which is not conducive to the full exhaust of the tank and is likely to cause great safety hazards to the maintenance and repair work of the gas-liquid separator. In particular, the corrugated bottom of the baffle plate used in the present application will further aggravate this phenomenon.

[0033] To overcome this problem, the method provides a longitudinally extending gas guide channel on the outer wall of the baffle plate assembly, and the gas guide channel is longitudinally completely open and has a plurality of second through holes in communication with the inside of the tank. When gas accumulates between the bottom surface of the baffle plate and the baffle plate assembly and cannot flow upward, it can enter the second through hole, enter the gas guide channel through the second through hole, and finally be discharged from the top end of the gas guide channel. It can be seen that the present solution can avoid the accumulation and retention of gas in the tank due to the structure and arrangement of the baffle plate, significantly improve the exhaust capacity of the tank, and significantly improve the safety of the gas-liquid separator during maintenance and repair.

[0034] It should be noted that the inner wall of the baffle plate assembly in the present application refers to the side wall facing the central area of the tank, i.e. the side wall radially inward; on the contrary, the outer wall of the baffle plate assembly refers to the side wall away from the central area of the tank, i.e. the side wall radially outward.

[0035] Further, the drilling fluid discharge channel comprises a discharge port provided on the side wall of the tank, and a first discharge pipe coaxial with and in communication with the discharge port; one end of the discharge port in communication with the inside of the tank is provided with a residue filter plate, and a reduced-diameter inner liner pipe is arranged in the discharge port, the large-diameter end of the reduced-diameter inner liner pipe is connected with the residue filter plate, and the small-diameter end extends into the first discharge pipe.

[0036] After degassing treatment, the drilling fluid is accumulated at the bottom of the tank, and when the liquid level reaches the height of the discharge port, the drilling fluid can be filtered through the residue filter plate and then discharged downstream through the reduced-diameter inner liner pipe in the discharge port. The discharge port is located on the side wall of the tank, so the area of the tank bottom below the discharge port can be used as a sedimentation area; the residue filter plate is used to filter large-size solid particles to prevent them from blocking the reduced-diameter inner liner pipe and the downstream pipeline; due to the gradually changing inner diameter of the reduced-diameter inner liner pipe, the flow rate of the fluid entering the reduced-diameter inner liner pipe gradually increases, which is beneficial to providing a faster initial flow rate for the fluid entering the first discharge pipe, facilitating more smooth liquid discharge to the downstream solid control system, and also facilitating subsequent gas return on the first discharge pipe.

[0037] Further, the first discharge pipe is closed at an end away from the end face of the discharge port, and a second discharge pipe is communicated with the bottom of the end of the first discharge pipe away from the discharge port;

[0038] The inner wall of the first discharge pipe is provided with a plurality of first baffles and second baffles staggered at the upper end and the lower end; the first baffles are inclined downward away from the discharge port; and the second baffles are inclined upward away from the discharge port.

[0039] Between any two adjacent first baffles, a first bypass pipe is arranged at the top of the first discharge pipe; all the first bypass pipes are communicated with a return pipe, the return pipe is communicated with the inside of the tank body, and the height of the position where the return pipe is communicated with the tank body is greater than or equal to the height of the centrifugal separator.

[0040] Between any two adjacent second baffles, a second bypass pipe is arranged at the bottom of the first discharge pipe; all the second bypass pipes are communicated with the second discharge pipe.

[0041] In the scheme, the first baffles and the second baffles jointly form a transverse baffling channel, the fluid sprayed at high speed through the reduced-diameter lining pipe fluctuates up and down between the first baffles and the second baffles to flow in a baffling manner, which can promote the formation of the gas-liquid phase interface again, and further separate the gas remaining in the drilling fluid again; and since the overall trend of the fluid in the first discharge pipe is transverse flow, the effect of gravity on the separation of the gas-liquid two phases is more obvious, the separated gas is gathered in the top region between the adjacent two first baffles, enters the return pipe through the first bypass pipe, and is finally returned to the inside of the tank body and discharged from the exhaust port; in addition, after the fluid sprayed at high speed through the reduced-diameter lining pipe enters the first discharge pipe, the flow rate is suddenly slowed down, which is also beneficial to the rapid stratification of the gas-liquid two phases.

[0042] Moreover, a large amount of small-particle solid cuttings impurities still exist in the fluid entering the first discharge pipe, and due to the presence of the second baffles, such particle impurities are easy to accumulate in the first discharge pipe to reduce the passage diameter or even cause blockage; therefore, the second bypass pipe is arranged between any two adjacent second baffles in the scheme, so that the cuttings particles or impurities accumulated between the adjacent second baffles can directly enter the second discharge pipe without unnecessary flow around, which significantly improves the stability of the drilling fluid discharge process of the present application and provides sufficient guarantee for the discharge efficiency of the present application.

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

[0044] 1. The vertical drilling fluid gas-liquid separator and gas-liquid separation method provided by the present application, the drilling fluid entering the inside of the tank body moves from top to bottom, sequentially passes through the centrifugal separator and the deflection assembly in the movement process, the gas-liquid two-phase separation is realized through the joint action of the centrifugal separator and the deflection assembly, the high-efficiency degassing of the returned drilling fluid is realized, and then the gas-liquid separation effect of the high-gas-content drilling fluid is improved.

[0045] 2. The present application can significantly improve the rotational flow field stability of the fluid doing centrifugal motion inside the cylinder body, and improve the uniformity of the velocity field distribution, thereby improving the rotational flow stability inside the cylinder body, being conducive to the aggregation of bubbles in the mixed fluid, being conducive to the formation of a stable rotating gas core, and thereby reducing the possibility of gas phase extending to the liquid discharge pipe and escaping; due to the significant improvement in the stability of the gas core, the gas-liquid two-phase inside the cylinder body can also form a clear interface, so that the liquid phase and the gas phase are not easily entrained with each other, and the gas-liquid separation effect is significantly improved.

[0046] 3. The present application can significantly reduce the pipe wall vibration, ensure the stability of the fluid entering the pipe and the tank body; at the same time, the generation of slug flow is significantly reduced, the vibration risk of the pipeline is further reduced, and the service life of the fluid inlet channel and the tank body is improved.

[0047] 4. 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 body 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.

[0048] 5. The present application can significantly reduce the erosion of the drilling fluid to the fluid inlet channel, prolong the service life and working stability of the fluid inlet channel, and facilitate regular sewage discharge, avoiding blockage caused by accumulation of solid precipitates in the drilling fluid or pipeline freezing.

[0049] 6. The deflection assembly of the present application forms a wavy flow pattern in macro and micro, which is more conducive to the separation of gas and liquid and improves the degassing capacity of the deflection assembly.

[0050] 7. The present application can avoid the accumulation and retention of gas inside the tank body due to the structure and arrangement form of the deflection plate, significantly improve the exhaust capacity inside the tank body, and significantly improve the operation safety during maintenance of the gas-liquid separator.

[0051] 8. The present application can significantly improve the stability of the drilling fluid during the discharge process, and can further separate gas and liquid during the liquid discharge process, thereby further improving the degassing quality. BRIEF DESCRIPTION OF DRAWINGS

[0052] The accompanying drawings, which are included to provide a further understanding of the embodiments of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings:

[0053] Figure 1 is a front view of an embodiment of the application;

[0054] Figure 2 is an isometric view of an embodiment of the application;

[0055] Figure 3 is a sectional view of an embodiment of the application;

[0056] Figure 4 is a schematic view of a centrifugal separator in an embodiment of the application;

[0057] Figure 5 is a schematic view of a half-section of a centrifugal separator in an embodiment of the application;

[0058] Figure 6 is a schematic view of a half-section of a fluid inlet channel in an embodiment of the application;

[0059] Figure 7 is a schematic view of a baffle assembly in an embodiment of the application;

[0060] Figure 8 is a Figure 7 is a close-up view of area A in Figure 1 1 ;

[0061] Figure 9 is a schematic view of a baffle assembly in an embodiment of the application;

[0062] Figure 10 is a schematic view of a half-section of a drilling fluid outlet channel in an embodiment of the application;

[0063] Figure 11 is a schematic view of a flow-blocking umbrella in an embodiment of the application;

[0064] Figure 12 is a schematic view of a gas guide channel in an embodiment of the application.

[0065] Reference signs and corresponding component names in the drawings:

[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 comprises a cylinder 301, an exhaust pipe 302 at the top of the cylinder 301, and a liquid discharge pipe 303 at the bottom of the cylinder 301; a plurality of annular support rods 306 are arranged at the bottom of the inside of the cylinder 301, the top ends of the support rods 306 are connected to a cyclone stabilizing disc 304, the cyclone stabilizing disc 304 is coaxial with the liquid discharge pipe 303, and the diameter of the cyclone stabilizing disc 304 is greater than the inner diameter of the liquid discharge pipe 303.

[0071] The centrifugal separator 3 further comprises an inlet pipe 305 connected 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] For the effect of the cyclone stabilizing disc 304 in the present embodiment, the present inventor has carried out simulation, and according to the simulated pressure and tangential velocity nephogram, after the cyclone stabilizing disc 304 is arranged, the cyclone region in the middle of the cylinder 301 is quite stable, the gas column is stably connected up and down, the velocity field is uniformly distributed, it is a stable cyclone process, which is conducive to the aggregation of the gas bubbles in the mixed liquid to form a stable rotating gas core. When the cyclone stabilizing disc 304 is not arranged, the effect is obviously not as good.

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

[0074] Considering that the traditional gas-liquid separator for drilling fluid is of an integrated structure, the entire separator shell and internal structure are integrally welded, and only a manhole is arranged on the surface, which is not convenient for maintenance and replacement; meanwhile, the existing separator is large in size and heavy in weight, which is not convenient for transportation, installation and maintenance. Therefore, in the present embodiment, the tank body 1 is longitudinally divided into a plurality of parts, and adjacent two parts are sealingly connected through flanges, which is convenient for replacement and maintenance.

[0075] In addition, the inlet pipe 305 and the fluid inlet channel 4 are also sealingly connected through flanges.

[0076] Preferably, the cross section of the inlet pipe 305 is rectangular or semicircular, and numerical simulation experiments of the present inventor have verified that the gas-liquid separation effect of the inlet pipe with a rectangular or semicircular cross section is better than that of a conventional circular structure. In addition, a spiral inlet pipe can also be adopted to strengthen the stratification of the gas-liquid phase in the inlet pipe 305 and improve the separation efficiency.

[0077] Preferably, as shown in Figure 3 Preferably, as shown in

[0078] In a more preferred embodiment, as shown in Figure 11 The bottom end of the baffle umbrella 20 is provided with an umbrella canopy 201, and a plurality of mounting holes 202 are uniformly distributed on the umbrella canopy 201. The top end of the baffle umbrella 20 is provided with an umbrella hole 203 for airflow. A mounting boss is arranged on the inner side wall of the tank body 1, which is used to cooperate with the umbrella canopy 201 so that the umbrella canopy 201 is seated on the mounting boss. Threaded holes corresponding to the mounting holes 202 are arranged on the mounting boss, and the umbrella canopy 201 is connected to the mounting boss by bolts.

[0079] Example 2:

[0080] A vertical drilling fluid gas-liquid separator, based on example 1, as shown in Figures 1 to 6 The fluid inlet channel 4 includes a fluid inlet pipe 401 and an inner pipe 402 coaxially fixed inside the fluid inlet pipe 401. The outer wall of the inner pipe 402 is fixed with spiral blades 403, and a plurality of first through holes 404 are arranged on the surface of the inner pipe 402. In the direction of fluid flow, the end of the inner pipe 402 close to the tank body 1 is open, and the end of the inner pipe 402 away from the tank body 1 is closed.

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

[0082] The top end of the fluid inlet pipe 401 is connected to a T-shaped joint 405. The top end of the T-shaped joint 405 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. The bottom end of the cross joint 406 is connected to the first blowdown valve 408. One of the other two ends of the cross joint 406 is closed, and the other end is used for drilling fluid to enter.

[0084] In this embodiment, the size of the spiral blade 403 matches the fluid inlet pipe 401. That is, in the cross section perpendicular to the axis of the fluid inlet pipe 401, the projection of the spiral blade 403 exactly fills the fluid inlet pipe 401.

[0085] In this embodiment, the aperture of the first through hole 404 is preferably in the order of millimeters.

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

[0087] Example 3:

[0088] A vertical drilling fluid gas-liquid separator, based on example 1 or 2, as shown in Figures 1 to 9As shown, the baffle assembly comprises a plurality of baffle plates 6 arranged in staggered manner on opposite sides of the inner wall of the tank body 1, the baffle plates 6 are wavy; and the baffle plates 6 gradually incline downward from one end close to the inner wall of the tank body 1 to one end away from the inner wall of the tank body 1.

[0089] The inner wall of the tank body 1 is fixedly connected with a baffle plate assembly 7, the inner wall of the baffle plate 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 screw holes 10 distributed along the longitudinal direction;

[0090] One end of the baffle plate 6 close to the inner wall of the tank body 1 is fixedly connected with an end plate 11, the end plate 11 is provided with a sliding part 12 matched with the guide groove 8 and a convex part 13 matched with the mounting protrusion 9, the opposite side walls of the convex part 13 are both provided with a plurality of second screw holes 14 distributed along the longitudinal direction, the second screw holes 14 are matched with the first screw holes 10.

[0091] In view of the problem that gas may accumulate below the baffle plate 6, the embodiment provides the following two solutions, which can be used alternatively or simultaneously, in particular:

[0092] Solution one:

[0093] As shown in the drawings, Figure 7 and Figure 8 A longitudinally extending gas guide channel 15 is arranged on the outer wall of the baffle plate assembly 7, the upper and lower ends of the gas guide channel 15 are open; a plurality of second through holes 16 are also arranged on the baffle plate assembly 7, one end of the second through hole 16 is located on the inner side surface of the baffle plate assembly 7, and the other end of the second through hole 16 is communicated with the gas guide channel 15.

[0094] Solution two:

[0095] As shown in the drawings, Figure 12 A plurality of gas guide grooves 21 are arranged on the inner wall of the baffle plate assembly 7, the upper and lower ends of the gas guide groove 21 penetrate the baffle plate assembly 7. Preferably, the inner wall of the baffle plate assembly 7 has two guide grooves 8, and one gas guide groove 21 is arranged beside each guide groove 8, and the gas guide grooves 21 are parallel to the guide grooves 8.

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

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

[0098] In a more preferred embodiment, the back of the baffle assembly 7, i.e. the radially outward side wall, is outwardly convex.

[0099] Embodiment 4:

[0100] A vertical drilling fluid gas-liquid separator, based on any of the above embodiments, as shown in Figures 1 to 10 the drilling fluid discharge channel 5 includes a discharge port 501 provided on the side wall of the tank body 1, a first discharge pipe 502 coaxial with and communicating with the discharge port 501; the discharge port 501 is provided with a residue filter plate 503 at one end connected to the inside of the tank body 1, and a reduced-diameter inner liner pipe 504 is provided in the discharge port 501, the large-diameter end of the reduced-diameter inner liner pipe 504 is connected to the residue filter plate 503, and the small-diameter end extends 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 communicated with a 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 downward away from the discharge port 501; the second baffles 507 are inclined upward away from the discharge port 501;

[0103] Between any two adjacent first baffles 506, there is a first bypass pipe 508 provided on the top of the first discharge pipe 502; all the first bypass pipes 508 are communicated to a gas return pipe 509, which is communicated to the inside of the tank body 1, and the position where the gas return pipe 509 is communicated to the tank body 1 is above the centrifugal separator 3 and below the flow-blocking umbrella 20;

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

[0105] In this embodiment, the discharge port 501 is located at a low position on the side wall of the tank body 1, and there is a gap between the discharge port 501 and the bottom of the tank body 1. When the tank body 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 greater than the inner diameter of the small-diameter end of the reduced-diameter inner liner pipe 504, and also greater than the inner diameter of the second discharge pipe 505.

[0107] More preferably, the included angle between the first baffles 506, the second baffles 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) located at the top of the cylinder (301), and a drain pipe (303) located at the bottom of the cylinder (301). Several ring-shaped 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).

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 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 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).

6. A vertical drilling fluid gas-liquid separator according to claim 5, characterized in that, 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 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).

7. A vertical drilling fluid gas-liquid separator according to claim 6, characterized in that, 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).

8. 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).

9. A vertical drilling fluid gas-liquid separator according to claim 8, 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).

10. A gas-liquid separation method based on any one of claims 1 to 9 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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