CN104196516B - Double-cylinder type two-stage axial flow down-hole degasser - Google Patents

Abstract

The invention provides a double-tube two-stage axial-flow downhole degassing device, which is installed between an oil well pump and a screen pipe, and is firstly used for gas-liquid two-phase separation before the output liquid of an oil and gas well enters the pump. Based on its double-tube special structure and two-stage axial flow technology, the degassing device realizes the separation of output liquid, gas and liquid, thereby improving the efficiency of the mechanical mining system; the liquid inlet keeps the screen tube and the inner liquid cylinder connected, and realizes the The speed of the produced liquid is increased; the axial flow tube assembly implements two-stage axial flow gas-liquid separation, and the axial flow tube adopts a standardized and block design to ensure efficient and thorough degassing of the produced liquid; the inner liquid cylinder ensures that the produced liquid Inject into the axial flow tube at a high initial velocity, and form a double-tube annular space together with the outer liquid cylinder, and transport the degassed liquid of the axial flow tube; the degassed liquid is first reversely integrated into a steady flow by the rectifier, and then It is discharged into the outer liquid cylinder by the liquid discharge device, and finally sent to the oil well pump after being accelerated by the deflector, and the gas is discharged into the wellbore after being decelerated and boosted by the exhaust device that can avoid backflow.

Description

Double-tube two-stage axial flow downhole degassing device

technical field

The invention is suitable for downhole degassing devices of oil and gas wells and unconventional gas wells, and in particular relates to a device for separating gas and oil, gas oil and water or gas and water before the produced liquid enters the pump.

Background technique

In the pumping system of oil and gas wells, the efficiency of the downhole pump plays a key role in the efficiency of the entire system. During the production operation of oil and gas wells, it is inevitable that the gas in the downhole production fluid enters the pump together with the liquid, and the existence of these gases directly leads to the low efficiency of the oil pumping system; In the oil process, if the necessary degassing measures are not adopted, it is easy to cause a large amount of gas to enter the oil well pump before the gas-liquid two-phase output liquid is fully separated, resulting in the occurrence of gas lock. For this reason, how to reduce the impact of gas in the produced fluid, improve the efficiency of the mechanical recovery system, and prevent the occurrence of gas lock phenomenon is an urgent problem to be solved in the normal production operation and efficient production of oil and gas wells.

Since the existence of gas in the produced fluid is the main factor affecting the reduction of the pump efficiency of the oil well pump, the most direct and effective measure is to use an downhole degassing device to ensure that the gas-liquid two-phase separation of the produced fluid is achieved before entering the oil well pump, and the maximum Minimize the gas content in the pump well fluid. At present, C-FER (The Center for Engineering Research Inc.) of Canada is cooperating with equipment manufacturers REDA and Vortoil to promote the industrialization of a spiral separator for downhole gas-liquid two-phase separation system. The spiral separator technology adopts The helical blade is a fixed piece of helical blade similar to the screw thread. The helical blade makes the air flow rotate under force to achieve separation, realizing the idea of gas-liquid separation and produced water injected into the formation at the same time; however, the working performance of the separator depends on the helical blade. The pitch, the number of heads, the diameter, and the flow rate of the airflow are not suitable for handling the liquid-containing airflow with a large volume flow rate. At the same time, there are certain difficulties in the manufacture of the spiral blade, and the welding technology between the spiral blade and the tank is relatively difficult and the weld seam Quality is difficult to guarantee. Domestically, Daqing Petroleum Institute has mainly designed downhole gas-liquid separation equipment, and carried out related process research. The water flow after downhole gas-liquid separation is injected back into the water injection layer, and the gas enters the production layer through the exhaust device. In the stage of ground separation test, it has not been seen to be practically applied in downhole gas-liquid separation.

To sum up, foreign downhole gas-liquid separation and reinjection technologies have many problems such as limited working performance and difficult manufacturing, while domestic research is only in the ground test stage. Therefore, on the basis of the existing feasible technology, using the simulation analysis results of gas-liquid two-phase flow in the oil pump and combining the field test results of the oil and gas wells in Shengli Oilfield and the unconventional gas wells in the Ordos Basin, the effects of different gas contents on the normal operation of the oil pump are studied. The influence of operation and pump efficiency provides an important basis for the optimal design of the degassing device; at the same time, a new type of two-stage axial flow downhole degassing device is developed by using new technology, new materials and processing technology, which will greatly improve the oil pumping efficiency of the mechanical recovery system and the oil and gas It is of great significance to save energy and reduce consumption of wells and improve comprehensive development benefits.

Contents of the invention

In order to overcome the defects and deficiencies in the existing downhole gas-liquid separation technology, the purpose of the present invention is to develop a new double-tube two-stage axial flow downhole degassing device suitable for gas-liquid separation of oil and gas well output. After the downhole degassing device is combined with the conventional downhole mechanical recovery system, the gas-liquid two-phase separation of the produced fluid before entering the pump is realized for the first time. Efficiency, prevention of gas lock phenomenon, and the goal of ensuring efficient production of oil and gas wells.

The technical scheme adopted by the present invention to solve the technical problem is to develop a double-tube two-stage axial flow downhole degassing device, which mainly consists of a liquid inlet, an inner liquid cylinder, an axial flow pipe assembly, a rectifier, a liquid drain, a drain The air device, the outer liquid cylinder and the deflector are composed of several parts. The downhole degassing device is directly suspended on the upper part of the fluid-producing layer in the well through the tubing string and auxiliary downhole tools along with the oil well pump and the sand control screen. The liquid container flows into the downhole degassing device, so that the inner liquid cylinder is filled with gas-liquid two-phase liquid with bottom-hole flow pressure, and the produced liquid enters the axial flow tube tangentially through the upper liquid inlet of the axial flow tube assembly for two-stage axial flow In the gas-liquid separation process, firstly, the output liquid forms two coaxial flows and co-rotating swirling flows in the upper straight pipe section. After flowing into the upper cone section, the increased angular momentum makes the friction between the output liquid and the cone wall The coefficient is small, the produced liquid rotates at a high speed, the gas migrates to the center of the axial flow tube to form a reversely rising gas column, and the produced liquid after the preliminary gas-liquid separation is gradually thrown to the tube wall, thereby realizing the first-stage axial flow After the gas-liquid separation, the produced liquid continues to flow into the lower straight pipe section, stays in the axial flow field for a period of time, and then flows into the lower cone section, the pipe section shrinks rapidly, and the produced liquid with high angular acceleration continuously accelerates during the axial flow process After rotating, the remaining gas in the produced fluid migrates to the center of the axial flow tube to form a gas column and merges with the gas column of the first stage axial flow, and after being boosted by the exhauster, it is discharged from the degassing device and enters the downhole tubing and casing The liquid is thrown to the pipe wall and flows downward axially to the rectifier and reversely integrates into a smooth flow, then flows into the annular space of the inner liquid cylinder and the outer liquid cylinder through the drainer, and finally enters the oil well pump through the deflector , and then lifted to the ground, since then the second stage of axial flow gas-liquid separation has been realized.

The liquid inlet is located at the bottom of the downhole degassing device, so that the screen tube and the inner liquid cylinder are connected to have the same bottomhole flow pressure, and at the same time, according to its ever-shrinking flow channel section, the speed of the produced fluid is increased to avoid the production fluid The small amount of fine sand carried by it is deposited in the chamber of the inner liquid cylinder. The liquid inlet includes a liquid inlet cover, a liquid inlet, a partition and a support rib, and the material of each part is made of two-way stainless steel. The shape of the liquid inlet cover is in the shape of a "bell mouth", which is composed of a shell, a cone and a backing plate from top to bottom. , there are evenly arranged threaded holes around the backing plate; the cone adopts a cylindrical inverted cone structure, the output liquid flows through the cone section and then enters the shell, and the diameter of the large end of the cone is equal to the diameter of the inner ring surface of the backing plate diameter, while the diameter of its small end circle is equal to the outer diameter of the shell; the outer surface of the shell adopts the structure of a combination of inverted cone and cylinder, while its inner surface adopts a streamlined structure with variable cross-section. The upper and lower parts of the line are straight line segments parallel to the axis of the liquid inlet, the upper middle part is a concave arc segment, while the lower middle part is a convex arc segment, and the straight line segment and the arc segment are tangent , and at the same time, the normals at the joints of the circular arcs overlap to ensure the continuity and stability of the output liquid flowing in the liquid inlet cover. The liquid inlet adopts a variable cross-section shuttle body structure, and its upper part is a cone to avoid the vortex of the output liquid at the outlet of the liquid inlet; the contour line of the liquid inlet profile matches the profile of the liquid inlet cover, and it is a straight line from top to bottom Section, convex and concave circular arc sections ensure that the flow channel in the liquid inlet has a variable cross-section annular structure with gradually shrinking area, so that the flow rate of the axially flowing output liquid in the flow channel is continuously increased. The clapboard adopts a ring-shaped plate structure, and the liquid inlet and the outer liquid cylinder are fixed through interference fit. The upper part of the inner ring surface of the clapboard is designed with a rectangular full-ring groove, and the screw holes evenly distributed under the groove are fastened with screws. The connection between the partition and the liquid inlet cover is realized after the parts are installed. The support rib adopts a rhombus-shaped strip structure with a number of four and is evenly arranged on the top of the liquid inlet cover to realize the positioning between the liquid inlet and the liquid inlet cover.

The inner liquid cylinder is used to accommodate the produced liquid that is still in gas-liquid two-phase in the downhole degassing device, while maintaining the internal pressure equal to the bottom hole pressure to ensure that the produced liquid is injected into the axial flow tube at a relatively high initial velocity A high-speed swirling flow is formed. The inner liquid cylinder includes a tube cover, an inner liquid cylinder body and a support plate, and the material of each part is made of two-way stainless steel. The inner liquid cylinder adopts the structure of a cylindrical cylinder and an inverted cone. The blind cover at the upper end is processed with an internal threaded hole in the center, and three threaded through holes are evenly arranged around it; the outer diameter of the cylindrical cylinder in the middle is equal to the backing plate of the liquid inlet cover The diameter of the outer ring surface; the diameter of the small end of the inverted cone at the lower part is equal to the outer diameter of the shell of the liquid inlet cover, and the inner liquid cylinder is fixed by circumferential welding with the cone of the liquid inlet cover, while the inverted cone The middle part of the body is processed with three circular holes corresponding to the position of the axial flow tube. The tube cover adopts an annular cylinder, and the center of the upper end cover is processed with a round hole, and the external thread on the outer ring surface of the lower cylinder is connected with the blind cover of the inner liquid cylinder to realize the positioning of the axial flow tube in the inner liquid cylinder. The strut plate adopts a cylindrical circular plate, and its central inner ring surface adopts an inverted conical surface with a taper of 20°. It cooperates with the shell of the liquid inlet cover to achieve positioning, so as to ensure the levelness of the strut plate and the alignment of the axial flow tube and the rectifier. Verticality: Three inverted conical holes corresponding to the position of the rectifier are evenly arranged around the support plate.

The axial flow tube assembly is used to implement two-stage axial flow gas-liquid separation to ensure efficient and thorough degassing of the produced liquid. The axial flow tubes are evenly arranged vertically along the circumferential direction in the inner liquid cylinder, and the axis of the axial flow tube assembly coincides with the central axis of the degassing device. In order to ensure the efficient degassing treatment of the produced fluid while considering the volume of produced fluid and the space limitation in the wellbore, the axial flow tube assembly is finally preferably a parallel connection of three axial flow tubes. The upper part of the axial flow tube is kept connected with the exhaust device through the overflow section, and the gap fit is adopted between the overflow section and the tube cover of the inner liquid cylinder; at the same time, the lower part of the axial flow tube is kept in contact with the outer liquid cylinder through the lower cone section, rectifier and liquid drainer. Unicom, and the lower cone section is fixed between the axial flow tube and the rectifier through circumferential welding.

The three axial flow tubes all adopt the same structure and size to achieve their standardized and block design. The axial flow tube adopts a special structure combining cones and cylinders, and the overall shape is an inverted cone with a thick top and a thin bottom, including The overflow section, the upper and lower straight pipe sections and the upper and lower cone sections are all made of two-way stainless steel and lined with epoxy resin.

The first-stage axial flow gas-liquid separation of the produced fluid is carried out in the upper straight pipe section and the upper cone section. The upper part of the straight pipe section is processed with liquid inlets arranged symmetrically along the circumferential direction, and the outlets of the liquid inlets are arranged clockwise to ensure that the produced liquid produces a rotating flow of the same direction in the axial flow tube. Each liquid inlet is a cylindrical channel with a certain diameter, and the outer end line of the horizontal section of the channel is tangent to the circumference of the upper straight pipe section, so as to ensure that the produced liquid enters the axial flow tube tangentially and forms two streams of coaxial flow. swirling flow. The diameter of the large end circular surface of the upper cone section is equal to the inner diameter of the upper straight pipe section, while the diameter of the small end circular surface is equal to the inner diameter of the lower straight pipe section. After the swirling flow enters the upper cone section from the upper straight pipe section, the angular momentum increases, and the distance between it and the cone wall The coefficient of friction becomes smaller, resulting in high-speed rotation.

The produced fluid is subjected to the second-stage axial flow gas-liquid separation in the lower straight pipe section and the lower cone section. The axial spacing decreases successively to ensure that the swirling flow stays in the lower straight pipe section for a short time. The diameter of the large end circular surface of the lower cone section is equal to the diameter of the small end circular surface of the upper cone section. At the same time, the distance between the upper cone section and the lower cone section of the axial flow tube along the axial direction decreases sequentially, while the taper of the cone surface increases sequentially. The optimal design is respectively 10° and 20°, to ensure that the pipe section shrinks rapidly after the rotating flow enters the lower cone section, the angular acceleration becomes larger, and the rotation speed continues to increase, so as to achieve the best separation effect of the remaining gas and liquid.

The overflow section is located at the upper end of the axial flow tube, and is used to ensure that the gas after the gas-liquid separation of the two-stage axial flow shrinks smoothly and overflows the axial flow tube. The upper part of the overflow section adopts flanges and elbows in turn, and the connection between the axial flow pipe assembly and the exhauster is realized through bolt fasteners; the outer ring surface of the lower part is processed with full rings arranged in layers at equal intervals Rectangular grooves, place ○-shaped sealing rings on the part where each layer of grooves matches with the inner liquid tube cover, so as to realize the sealing between the inner liquid tube and the axial flow tube; at the same time, the overflow section realizes its connection with Positioning between inner liquid cylinders. The inner ring surface of the overflow section adopts a structure combining a conical surface and a curved cylindrical surface to ensure that the volume is continuously reduced and the flow pressure is gradually increased when the gas overflows, so that it can be discharged smoothly. The axis of the inlet of the overflow section coincides with the axis of the axial flow tube, while the axis of the outlet is at 45° to the horizontal plane to reduce the pipe resistance loss caused by the change of air flow direction.

The rectifier is connected to the axial flow pipe at the top and the drainer at the bottom, and the degassed liquid flows downward to the rectifier for reverse integration and becomes a steady flow, so that the flow pressure can be restored and increased. The evenly distributed positions of the three rectifiers correspond to the axial flow tubes. Each rectifier includes a rectifying cylinder, rectifying blades, rectifying rods and rectifying wheels. Except for the rectifying blades, other parts are made of two-way stainless steel. The rectifying cylinder adopts a cylindrical structure, and the lower part of the outer ring surface adopts an inverted conical structure with a taper of 20°, which is matched with the hole of the inner liquid cylinder support plate to achieve positioning, and the diameter of the inner ring surface is equal to the small end of the lower cone section of the axial flow tube The diameter of the circular face. The rectifier rod and the rectifier are coaxially arranged, and the structure of the combination of the cone and the rod body is adopted. The upper cone is used to guide the liquid to the rectifier vanes smoothly, and the lower cone is used to guide the reversely integrated liquid smoothly. to the rectifier wheel and avoid localized vortices after the liquid leaves the guide vanes. The rectifying wheel is used to turn the liquid into a steady flow. In order to maintain the fluidity of the liquid, the wheel shaft adopts a thin-walled circular tube, and the eight wheel pieces are vertically evenly arranged along the outer ring surface of the wheel shaft. The upper part of each wheel piece adopts an isosceles triangle cross section. Advanced tip structure to reduce friction when liquid cuts in.

The rectifying vane is used to reversely integrate the degassed liquid, and its material is 60Si2Mn, and the quenching and tempering treatment has a Brinell hardness greater than 230. Each rectifier includes two rectifying blades arranged uniformly along the circumferential direction, and fixed on the rectifying rod by welding. The tooth line of the rectifying blade is a helix extending along the outer ring surface of the rectifying rod, the height of the helix is equal to the height of the rod body of the rectifying rod, and the pitch increases gradually. The rectifying blade is isosceles trapezoidal at the end face of the normal surface perpendicular to the tooth line, and the inside is wide and the outside is narrow to ensure the stiffness and strength of the rectifying blade, while maintaining a continuous and stable liquid film on the blade. The height of the end face of the upper half of the pitch remains unchanged along the tooth line, the diameter of the cylindrical surface where the end face of the face is located is equal to the diameter of the inner ring surface of the rectifier, and the rectification is realized by interference fit with the rectifier The fixing of blades and rectifying rods; while the height of the normal surface of the lower quarter of the pitch decreases continuously along the tooth line, so the contact area of the liquid on the rectifying blades is gradually reduced to ensure that the flow pressure of the liquid is gradually reduced during the reverse integration process. Pick up and eventually flow smoothly out of the straightening blades.

The liquid drainer is used to smoothly discharge the degassed liquid of the produced liquid into the outer liquid cylinder. It includes a liquid discharge pipe and a liquid discharge wheel, and the material is two-way stainless steel. The inlet section of the discharge pipe adopts an elbow to realize the 45° direction change of the liquid from the rectifier to the liquid discharger; after that, the liquid flows into the pressurized section, and the cross-sectional area of the pressurized section gradually increases, so that the kinetic energy of the liquid is transformed into an enthalpy increase. The flow pressure of the liquid is improved; the outer ring surface of the discharge pipe adopts a structure combining a conical surface and a cylindrical surface, wherein the cylindrical surface and the circular hole at the lower part of the inner liquid cylinder are connected through clearance fit. The liquid discharge wheel is located at the outlet section of the liquid discharge pipe, and its structure is similar to the rectifier wheel in the rectifier to ensure that the degassed liquid is finally injected into the outer liquid cylinder smoothly.

The outer liquid cylinder is located at the outermost layer of the downhole degassing device, and together with the inner liquid cylinder forms a double-tube annular space for liquid flow, which is used to transport the degassed liquid of the axial flow tube upward to the deflector. The material of the outer liquid cylinder is made of 45 steel, the outer surface of which is spray-welded, while the surface of the inner wall is treated with electroless plating, the thickness of the coating is greater than 0.08mm, and the spray-welded layer and the coating are firmly combined with the base metal. The upper and lower ends of the outer liquid cylinder are processed with external threads, the upper end is connected to the oil well pump through a coupling, and the lower end is connected to the screen pipe through a coupling. The upper part of the outer liquid cylinder is processed with three circular holes uniformly arranged along the circumferential direction, and the axis of the holes is 45° to the horizontal plane.

The degasser is used to decelerate and pressurize the gas released from the produced fluid and discharge it into the annular space of the downhole tubing and casing, and at the same time prevent the fluid in the wellbore from being reversed to degassing through the degasser when the bottom hole pressure fluctuates and becomes low during operation device. The evenly distributed position of the three exhausters corresponds to the axial flow tube, each exhauster includes a pressure control valve and a diffuser tube, the axis of the exhauster coincides with the axis of the outlet of the overflow section of the axial flow tube and is at a 45° angle to the horizontal plane °. The diffuser tube adopts the combination of flange, cone and cylinder in turn. The taper of the inner ring surface is smaller than the taper of the outer ring surface. After being compressed, it slows down and the pressure increases. A pressure control valve is connected to the outlet of the diffuser tube to ensure that the gas is smoothly discharged into the wellbore after the pressure is increased, and at the same time to avoid the backflow of the fluid in the wellbore under the condition of bottom hole pressure fluctuations.

The deflector is located at the uppermost part of the downhole degassing device, and the liquid in the outer liquid cylinder is sent to the oil pump after the speed is increased, so as to avoid deposition in the outer liquid cylinder when the liquid carries sand particles. The deflector includes a deflector and a deflector cone. The axes of the deflector and the deflector cone coincide with the central axis of the degassing device, and the upper end surfaces are flush with the upper end surface of the outer liquid cylinder to realize the positioning of the deflector. . The material of the liquid guide cover is 35CrMo, the surface of the cover is oxidized, and the Brinell hardness of the tempering treatment is not less than 220; the material of the diversion cone is 60Si2Mn, and the Brinell hardness of the quenching and tempering treatment is greater than 230. The liquid guide cover adopts a variable cross-section rotary body structure, and its lower end is higher than the outlet of the pressure control valve of the exhauster, and the diameter of the outer ring surface is equal to the inner diameter of the outer liquid cylinder, and is fixed with the outer liquid cylinder by interference fit; The inner wall of the liquid cover adopts a streamline shape, and the upper part of the axial section contour line is a convex arc segment, the tangent line at the outlet of the arc segment is parallel to the axis of the deflector, and the lower part is a concave circular segment. The arc segment, the tangent at the entrance of the arc segment is parallel to the axis of the deflector. The diversion cone adopts a variable cross-section conical structure with thin ends and thick middle, and the outer thread is processed on the cylindrical surface at the bottom, which is connected with the inner liquid cylinder to realize the fixation of the diversion cone; the diversion cone and the diversion cover The channel for ensuring the flow of the liquid is in the form of a ring-shaped structure with a gradually decreasing cross-sectional area after being used together, so as to realize the continuous increase of the flow rate of the liquid. The outer contour line of the axial section of the diversion cone matches the contour line of the diversion cover section. Axially uniform outflow; the middle part is a convex arc segment, and the normal lines at the joints of the two ends of the arc segment are coincident to ensure the continuity of the liquid in the flow channel of the deflector; the lower part is a concave arc segment, the circle The tangent at the entrance of the arc segment is parallel to the axis of the deflector, so as to ensure that the liquid in the outer liquid cylinder flows into the deflector smoothly along the axial direction.

The technical effect achieved by the present invention is that the downhole degassing device realizes the gas-liquid two-phase separation of the produced liquid before entering the pump according to its double-barrel special structure and two-stage axial flow technology, thereby improving the efficiency of the mechanical mining system , to prevent the occurrence of gas lock and ensure the efficient production of oil and gas wells; the liquid inlet keeps the screen and the inner liquid cylinder in communication, and according to its continuously shrinking flow channel section, the speed of the produced liquid is increased to avoid the deposition of fine sand particles; the inner liquid The cylinder is used to maintain the internal pressure equal to the bottom hole pressure to ensure that the produced fluid is injected into the axial flow tube at a high initial velocity to form a high-speed rotating flow; the outer liquid cylinder and the inner liquid cylinder together form a double-tube annular space for liquid flow. It is used to transport the liquid degassed by the axial flow tube; the axial flow tube assembly realizes the two-stage axial flow gas-liquid separation of the downhole produced liquid, ensuring that the produced liquid is degassed efficiently and thoroughly; the rectifier is equipped with rectifying blades, The liquid after the degassing of the produced liquid is reversely integrated and turned into a steady flow, and the flow pressure can be restored and increased; the deflector sends the liquid in the outer liquid cylinder to the oil well pump after increasing the speed, so as to avoid the deposition of sand particles; The liquid device is used to smoothly discharge the degassed liquid into the outer liquid cylinder, and the degasser is used to decelerate and increase the pressure of the gas from the produced fluid and discharge it into the wellbore, while preventing the fluid in the wellbore from backflow through the degasser.

Description of drawings

Fig. 1 is a schematic diagram of a typical structure of a double-tube two-stage axial-flow downhole degassing device proposed according to the present invention.

Fig. 2 is a cross-sectional view along line A-A of Fig. 1 .

Fig. 3 is a schematic structural diagram of a liquid inlet in a double-tube two-stage axial flow downhole degassing device.

Fig. 4 is a schematic structural diagram of the inner liquid cylinder in the double-tube two-stage axial flow downhole degassing device.

Fig. 5 is a schematic structural diagram of an axial flow tube in a double-tube two-stage axial flow downhole degassing device.

Fig. 6 is a schematic structural diagram of a rectifier in a double-tube two-stage axial flow downhole degassing device.

Fig. 7 is a schematic structural diagram of a liquid drainer in a double-tube two-stage axial flow downhole degassing device.

Fig. 8 is a schematic structural diagram of the exhaust device in the double-tube two-stage axial flow downhole degassing device.

Fig. 9 is a schematic structural diagram of the deflector in the double-tube two-stage axial flow downhole degassing device.

Fig. 10 is a schematic diagram of the gas-liquid separation process of the double-tube two-stage axial flow downhole degassing device.

In the figure, 1- deflector, 2- exhauster, 3- outer liquid cylinder, 4- inner liquid cylinder, 5- axial flow tube assembly, 6- rectifier, 7- liquid drainer, 8- liquid inlet, 9-supporting ribs, 10-inlet liquid, 11-inlet liquid cover, 12-baffle, 13-tube cover, 14-inner liquid cylinder, 15-supporting plate, 16-overflow section, 17-upper straight pipe section, 18 - upper cone section, 19 - lower straight pipe section, 20 - lower cone section, 21 - straightening cylinder, 22 - rectifying blade, 23 - rectifying rod, 24 - rectifying wheel, 25 - draining wheel, 26 - draining pipe, 27-pressure control valve, 28-diffuser pipe, 29-drilling cover, 30-draining cone.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited to the following embodiments.

In Fig. 1 and Fig. 2, the double-tube two-stage axial-flow downhole degassing device consists of a deflector 1, an exhaust device 2, an outer liquid cylinder 3, an inner liquid cylinder 4, an axial flow pipe assembly 5, and a rectifier 6. , drainer 7 and liquid inlet 8, when in operation, the downhole degassing device is connected to the oil well pump and the sand control screen through the coupling, and goes downhole directly along the casing string along with the tubing string and auxiliary downhole tools, Finally, it is suspended on the upper part of the fluid-producing layer in the well. When assembling, the liquid inlet 8 is first fixed on the bottom of the outer liquid cylinder 3, and then the axial flow tubes, rectifiers 6 and liquid dischargers 7 of each axial flow tube assembly 5 are respectively welded into three single bodies, and are connected with the inner tubes in sequence. After the liquid cylinder 4 is connected, it is inserted into the liquid inlet 8, and then each exhaust device 2 is fixed on the upper part of the outer liquid cylinder 3, and connected with each axial flow tube of the axial flow tube assembly 5 through fasteners, and finally the deflector The deflector cone of 1 is connected to the top of the inner liquid cylinder 4, and the deflector 1 deflector is embedded in the top of the outer liquid cylinder 3. After the downhole degassing device is assembled, the outer liquid cylinder 3 is finally painted.

In Fig. 1 and Fig. 2, when debugging the double-tube two-stage axial-flow downhole degassing device, the hydraulic test and the air tightness test are first carried out on the whole device; then, check whether each weld is qualified and whether each joint is properly connected; Finally, check whether the connecting threaded fasteners are loose and corroded. During maintenance during workover operations, each component needs to be inspected and repaired separately. First, check the inner liquid cylinder 4, the axial flow pipe inlet of the axial flow pipe assembly 5, the liquid drainer 7 and the outer liquid cylinder 3 for accumulation of foreign matter. , and then check whether the surface of the rectifier blades of the rectifier 6 is corroded, and replace it if necessary, and then check the dirt on the axial flow tubes of the axial flow tube assembly 5, the deflector 1 and the liquid inlet 8, and if necessary, use alkali cleaning or Cleaning solution for cleaning.

In Fig. 3, the liquid inlet 8 is fixed on the bottom of the outer liquid cylinder 3 through the partition plate 12, and the shell of the liquid inlet cover 11 cooperates with the inner ring surface in the center of the support plate of the inner liquid cylinder 4 so that the screen tube and the inner liquid cylinder 4 Stay in touch with each other. The liquid inlet 10 is connected to the top of the liquid inlet cover 11 through the support ribs 9, and the liquid inlet 10 cooperates with the liquid inlet cover 11 to gradually reduce the cross section of the flow channel in the liquid inlet 8, thereby realizing the continuous increase of the flow rate of the oil and gas well output fluid.

In Fig. 4, the inner liquid cylinder 4 is connected to the liquid inlet 8 through the joint action of the support plate 15 and the inverted cone at the lower part of the inner liquid cylinder 14, and the inner liquid cylinder 4 is accommodated by the inner liquid cylinder 14. sand-treated oil and gas wells that have not been degassed, and the degassed liquid in the outer liquid cylinder 3 and the undegassed produced fluid in the inner liquid cylinder 4 are separated by the pipe cover 13 to ensure that the inner The produced fluid in the liquid cylinder 4 always maintains the internal pressure of the bottom hole pressure.

In Fig. 5, the axial flow tube assembly 5 is located in the inner liquid cylinder 4, and the two-stage axial flow gas-liquid separation of the produced liquid is completed based on three vertically evenly arranged axial flow tubes, in which the produced liquid is first in the upper straight pipe section 17 and the upper cone section 18 rotate at high speed to complete the first stage of axial flow gas-liquid separation, and then the rotation speed in the lower straight pipe section 19 and the lower cone section 20 continues to increase again to complete the second stage of axial flow gas-liquid separation. The gas after gas-liquid separation shrinks smoothly through the overflow section 16 at the upper end of the axial flow tube and overflows the axial flow tube, while the liquid after gas-liquid separation continues to axially flow downward to the rectifier 6 through the outlet of the lower cone section 20, thus making The produced fluid is efficiently and thoroughly degassed.

In Fig. 6, the rectifier 6 is integrated with the axial flow tube and the liquid drainer 7 by welding, so that the axial flow tube and the outer liquid cylinder 3 are kept in communication, and the lower part of the rectifier tube 21 is embedded in the hole of the support plate 15 to realize the axial flow tube. Positioning in the inner liquid cylinder 4, the degassed liquid is smoothly diverted to the rectifying blade 22 through the upper cone of the rectifying rod 23, and after reverse integration, it is led to the rectifying wheel 24 by the lower cone of the rectifying rod 23 to form a smooth flow. flow.

In Fig. 7, the liquid drainer 7 is embedded in the round hole in the middle of the inverted cone of the inner liquid cylinder 4, and the steady flow at the outlet of the rectifier wheel 24 continues to flow downward to the drain pipe 26. The liquid wheel 25 injects the degassed liquid from the axial flow tube smoothly into the double-tube annular space formed by the outer liquid cylinder 3 and the inner liquid cylinder 4 .

In Fig. 8, the upper part of the exhauster 2 is embedded in the circular hole in the upper part of the outer liquid cylinder 3, while the lower part is integrated with the axial flow tube through bolt connection and kept connected. The overflow section 16 of the flow pipe enters the diffuser pipe 28 of the exhauster 2, the gas is compressed to decelerate and increase the pressure, and then is discharged into the annular space of the downhole tubing and casing through the pressure control valve 27. When the gas pressure after deceleration and boosting is lower than the flow pressure in the annular space of the tubing and casing, the pressure control valve 27 is automatically closed, and when the gas pressure is higher than the flow pressure in the annular space again, the pressure control valve 27 is automatically opened .

In Fig. 9, the deflector 1's deflector 29 is embedded in the top of the outer liquid cylinder 3, and the deflector cone 30 is threaded on the top of the inner liquid cylinder 4 to cooperate with the deflector 29, so that the deflector 1 The cross-section of the inner annular channel is continuously reduced, so that the liquid in the outer liquid cylinder 3 enters the deflector 1 after the flow rate is increased and then enters the oil well pump.

In Fig. 10, the specific process of gas-liquid separation of oil and gas well output liquid is as follows: the output liquid flows into the downhole degassing device after being desanded by the screen, first passes through the liquid inlet 8 to increase its flow rate, and then passes through the inlet liquid 10 and the liquid inlet cover 11 enter the inner liquid cylinder 4, and the pressure of the produced fluid in the screen pipe, the liquid inlet 8 and the inner liquid cylinder 4 is equal to the flow pressure at the bottom of the well; then the produced fluid passes through the axial flow tube assembly 5 The liquid inlet at the upper part of the flow tube injects tangentially into the upper straight pipe section 17, and forms two coaxial flows and corotating swirling flows, then accelerates the axial flow to the upper cone section 18, where the angular momentum of the produced fluid increases and further High-speed rotation, the high-speed axial flow in the upper straight pipe section 17 and the upper cone section 18 makes the gas in the produced liquid migrate to the center of the axial flow pipe to form a reversely rising gas column, while the produced liquid after preliminary gas-liquid separation is Gradually flung towards the pipe wall; after that, the produced fluid continued to flow downward to the axial flow field of the lower straight pipe section 19, and after staying in the axial flow field of the lower straight pipe section 19 for a period of time, it flowed into the lower cone section 20, where a greater angular acceleration was obtained and continued at high speed. Accelerated rotation, the further accelerated axial flow in the lower straight pipe section 19 and the lower cone section 20 makes the remaining gas in the produced liquid move to the center of the axial flow pipe again to form a gas column, and rises in the opposite direction to the gas column of the first axial flow. The columns converge to form the same gas column, which enters the exhauster 2 from the overflow section 16, and finally boosts the pressure through the diffuser 28 and sends it to the annular space of the downhole tubing and casing through the pressure control valve 27. At this time, the air in the exhauster 2 The pressure of the gas is higher than the flow pressure in the annular space of the oil pipe and the casing; while the degassed liquid is thrown to the pipe wall and collected in the lower cone section 20, then flows downward to the rectifier 6, and is reversely integrated by the rectifier blades 22 Afterwards, it flows to the rectifier wheel 24 to form a steady flow, and then through the liquid discharge pipe 26 of the liquid discharger 7 to increase the flow pressure, it is stably injected into the outer liquid cylinder 3 by the liquid discharge wheel 25, and finally flows through the outer liquid cylinder 3 and the inner liquid cylinder. The double cylinder annular space of 4 is transported to the deflector 1, and enters the oil well pump after being accelerated by the deflector cover 29 and the deflector cone 30. The pressures at the inlets of the well pumps are all equal.

Claims (10)

1. a double-cylinder type two-stage axial flow down-hole degasser, after computer collecting system is combined under conventional well, special according to its double-cylinder type Structure and two-stage axial flow technology, it is achieved production fluid gas-liquid two-phase before entering pump separates, it is characterised in that:

One liquid inlet device；The feed liquor cover profile of described liquid inlet device presents " horn mouth " shape, and production fluid flows through conic section and shrinks laggard Entering housing, the outer surface of housing uses inverted cone and the structure of cylinder combination, and its inner surface then uses the streamline of variable cross-section Shape structure；Feed liquor body uses the shuttle body structure of variable cross-section, and the contour line of its section matches with feed liquor cover section, stream in liquid inlet device Road is area diminishing variable cross-section loop configuration, and dividing plate realizes fixing between liquid inlet device and outer fluid cylinder by interference fit；

Fluid cylinder in one；The interior fluid cylinder body of described interior fluid cylinder uses the structure of cylindrical tube and inverted cone combination, fagging central authorities internal ring The rounding conical surface that face uses tapering to be 20 °, matches with the housing of feed liquor cover and realizes location；

One axial flow pipe assembly；The axial flow pipe of described axial flow pipe assembly is the most vertical in interior fluid cylinder to be evenly arranged, three axles Flow tube all uses identical structure and size, and axial flow pipe uses the special tectonic that cone and cylinder combine, under entirety presents slightly Thin inverted cone；Production fluid implements first order axial flow gas-liquid separation in upper straight length and upper cone section, and at lower straighttube section and lower cone Second level axial flow gas-liquid separation is implemented in section；Upper straight length and the lower straighttube section spacing vertically of axial flow pipe are sequentially reduced, and on Cone section and lower cone section spacing vertically are sequentially reduced, and the tapering of the conical surface increases successively；Overflow between being machined with on gas section outer ring surface etc. Away from the loopful rectangular recess of layered arrangement, and its inner ring surface uses the structure that taper seat combines with bending cylinder；

One commutator；The uniform position of described commutator is corresponding with axial flow pipe, and flow regulating barrels outer ring surface bottom uses tapering to be 20 ° Turbination structure, rectification bar is coaxially arranged with commutator, uses the structure that cone and the body of rod combine, eight of rectification wheel Wheel sheet is vertical evenly distributed along wheel shaft outer ring surface；Each commutator comprises two straightener(stator) blades the most evenly distributed, whole The pitch of stream blade is gradually increased, and straightener(stator) blade is isosceles trapezoid at the normal plane end face being perpendicular to tooth trace, and in wide outer the narrowest, on The normal plane face height of portion 1/2nd pitch keeps constant along tooth trace, and the normal plane face height of bottom 1/4th pitch is along tooth Line constantly reduces, and liquid contact area on straightener(stator) blade is gradually reduced；

One drain pump；The area in the discharging tube boost section cross section of described drain pump is gradually increased so that the kinetic energy of liquid is changed into enthalpy Increasing, stream pressure is improved, the rectification wheel that discharge opeing wheel construction is similar in commutator；

One outer fluid cylinder；Described outer fluid cylinder forms the bitubular annular space of liquid flowing together with interior fluid cylinder；

One deaerator；Described deaerator axis coincides with axial flow Guan Yiqi section outlet axes, the tapering of the diffuser pipe inner ring surface conical surface Less than the tapering of outer ring surface, at cone, the cross section of runner gradually tapers up, and diffuser pipe exit connects pressure-control valve；

One air deflector；The kuppe of described air deflector and the axis of deflection cone overlap with the axis of degasser, upper surface all with The upper surface flush of outer fluid cylinder；Drain cover uses variable cross-section rotary structure, and its lower end is higher than deaerator pressure control valve outlet The position at place, and inwall uses streamlined；Deflection cone uses variable cross-section pyramidal structure thick between two ends details, deflection cone with lead Stream cover is the diminishing annular configuration of cross-sectional area with the use of the passage of rear guarantee liquid flowing, and deflection cone axially cuts open Face outer contour matches with the contour line of kuppe section.

Double-cylinder type two-stage axial flow down-hole the most according to claim 1 degasser, it is characterised in that: the pad of described feed liquor cover Using matched in clearance between plate outer ring surface and partition groove, cone big end disc diameter is equal to the diameter of backing plate inner ring surface, and its small end Disc diameter is then equal to housing outer diameter；

The upper and lower of the axial cross sectional profile line of the shell inner surface of described feed liquor cover is the straight line parallel with liquid inlet device axis Section, middle and upper part is the arc section of up concave type, and middle and lower part is the arc section of upwards-raised.

Double-cylinder type two-stage axial flow down-hole the most according to claim 1 and 2 degasser, it is characterised in that: described liquid inlet device The liquid upper that enters be cone, the contour line of its section is from top to bottom followed successively by the arc section of straightway, upwards-raised and up concave type；

The dividing plate of described liquid inlet device uses annular plate-like structure, and its inner ring surface upper design has rectangle loopful groove；

The brace rod of described liquid inlet device uses cross section to be the list structure of rhombus, and quantity is four and is evenly arranged in feed liquor cover top.

Double-cylinder type two-stage axial flow down-hole the most according to claim 1 degasser, it is characterised in that: in described interior fluid cylinder body The cylindrical tube external diameter in portion is equal to the diameter of feed liquor hood pad plate outer ring surface, and the inverted cone small end disc diameter of bottom is equal to feed liquor The external diameter of over body case, the middle part of inverted cone is machined with three circular aperture corresponding with axial flow pipe position simultaneously；

External screw thread on the external anchor ring of lid lower post of described interior fluid cylinder realizes axial flow pipe at interior liquid after coupling with interior fluid cylinder body blind cover Location in Tong；

The fagging surrounding of described interior fluid cylinder is evenly arranged three turbination eyelets corresponding with commutator position；

Described outer fluid cylinder upper end is coupled with oil well pump by box cupling, and lower end is coupled with screen casing by box cupling；Outer fluid cylinder top processes Having three circular aperture the most evenly distributed, eyelet axis is with the horizontal 45 °.

Double-cylinder type two-stage axial flow down-hole the most according to claim 1 degasser, it is characterised in that: described axial flow pipe assembly Axis overlap with the axis of degasser, axial flow pipe top keeps through by excessive gas section and deaerator, gas section of overflowing and interior liquid Using matched in clearance between the lid of cylinder, axial flow pipe bottom keeps UNICOM by lower cone section, commutator and drain pump with outer fluid cylinder simultaneously.

Double-cylinder type two-stage axial flow down-hole degasser the most according to claim 1 or 5, it is characterised in that: described axial flow pipe The top of upper straight length is machined with the inlet being along the circumferential direction arranged symmetrically with, and the outlet of inlet is along arranged clockwise, Mei Gejin The outer end line of liquid oral pore road horizontal profile is tangent with the circumference of upper straight length position；

The big end disc diameter of described axial flow pipe upper cone section is equal to the internal diameter of upper straight length, and small end disc diameter is equal to lower straighttube section Internal diameter；

Described axial flow pipe lower straighttube section realizes the connection between two-stage axial flow gas-liquid separation pipeline section, and the diameter of lower cone section big end disc is equal to The diameter of upper cone section small end disc；

Described axial flow Guan Yiqi section realizes the location between itself and interior fluid cylinder by the upper surface of upper straight length, overflow gas section inlet axis with The axis of axial flow pipe coincides, and outlet axes is then with the horizontal 45 °.

Double-cylinder type two-stage axial flow down-hole the most according to claim 1 degasser, it is characterised in that: described commutator whole Flow cartridge outer ring surface matches with the eyelet of interior fluid cylinder fagging and realizes location, and its inner ring surface diameter is equal to axial flow pipe lower cone section small end The diameter of disc；

The rectification bar top cone of described commutator is used for being guided on straightener(stator) blade liquid smoothly, and its underpart cone is used for inciting somebody to action Liquid after reversely integrating causes rectification wheel smoothly；

The rectification wheel wheel shaft of described commutator uses thin-wall circular tube, and each employing cross section, top taking turns sheet is the tip of isosceles triangle Structure.

8. according to the double-cylinder type two-stage axial flow down-hole degasser described in claim 1 or 7, it is characterised in that: described rectification leaf The tooth trace of sheet is the helix launched along rectification bar outer ring surface, and the height of helix is equal to the height of rectification club shaft；

The diameter on the face of cylinder, normal plane end face lateral surface place of described straightener(stator) blade top 1/2nd pitch is equal to flow regulating barrels inner ring surface Diameter, and and flow regulating barrels between use interference fit to realize the fixing of straightener(stator) blade and rectification bar.

Double-cylinder type two-stage axial flow down-hole the most according to claim 1 degasser, it is characterised in that: the row of described drain pump Liquid tube inlet section uses elbow, it is achieved liquid is by the change of commutator to 45 ° of directions of drain pump；Discharging tube outer ring surface uses the conical surface The structure combined with cylinder, its central column face is coupled by matched in clearance with the circular aperture of interior fluid cylinder body bottom；

The uniform position of described three deaerators is corresponding with axial flow pipe, and diffuser pipe uses ring flange, cone to tie mutually with cylinder successively The structure closed.

Double-cylinder type two-stage axial flow down-hole the most according to claim 1 degasser, it is characterised in that: described air deflector Drain cover outer ring surface diameter be equal to outer fluid cylinder internal diameter, and and outer fluid cylinder between use interference fit be fixed；

The top of the drain cover axial cross sectional profile line of described air deflector is the arc section of upwards-raised, cutting of place, arc section exit Line is paralleled with air deflector axis, and its underpart is the arc section of up concave type, the tangent line at place, arc section porch and air deflector axle Line is parallel；

The top of the deflection cone axial section outer contour of described air deflector is the arc section of up concave type, place, arc section exit Tangent line is paralleled with air deflector axis, and middle part is the arc section of upwards-raised, and the normal of junction, arc section two ends all overlaps, bottom Arc section in up concave type, the tangent line at place, arc section porch is paralleled with air deflector axis.