Constant-speed gas lift equipment for scaling prevention of high-temperature well

Abstract

The invention discloses constant-speed gas lift equipment for scaling prevention of a high-temperature well, and relates to the technical field of gas production processes, and the constant-speed gas lift equipment comprises an anti-scaling gas lift flowing device and a constant-speed gas lift flowing device which are connected to an oil pipe in series; the anti-scale gas lift flowing device comprises a first barrel; a plurality of first gas lift gas injection channels are formed in the annular side wall of the first barrel; the first gas lift gas injection channel is inclined towards the gas-liquid flowing direction; each first gas lift gas injection channel further communicates with an anti-scaling agent channel formed in the first barrel. The constant-speed gas lift flowing device comprises a second barrel; a plurality of second gas lift gas injection channels are formed in the annular side wall of the second barrel; and the second gas lift gas injection channel is inclined towards the flowing direction of the well liquid. By adopting the scheme, the flowing direction of high-pressure gas is almost consistent with that of fluid in a shaft, and the high-pressure gas transmits kinetic energy to liquid flowing along the pipe wall at a low speed, so that liquid slippage is reduced, and the gas lifting efficiency is improved.

Description

Technical Field

[0001] The invention relates to the technical field of gas production technology, and in particular to a constant speed gas lift device for preventing scaling in high temperature wells. Background Art

[0002] The gas lift process is an artificial lifting process that injects high-pressure gas into the oil pipe through a high-pressure gas source to reduce the flow pressure gradient above the gas injection point, reduce the slip loss during the lifting process, discharge the bottom hole liquid, increase the production pressure difference, and restore or improve the production capacity of the gas well. Compared with other processes, the gas lift process has great advantages. It has a wide range of applications, a low failure rate, and a long maintenance-free period.

[0003] 1. Regarding flow performance: The use of gas lift valves is currently the main process for water drainage and gas production in gas lift, but the current process has the following problems:

[0004] 1) Natural gas and water flow upward from the bottom of the well to the wellhead, while when the conventional gas lift injection gas enters the working cylinder from the annulus through the gas lift valve, the injection direction of the injection gas is downward, see Figure 3 The direction of gas lift ejection from the middle working cylinder. The downward-flowing injected gas will cause a large amount of energy loss, and the gas lift efficiency and gas lift stability will be greatly reduced.

[0005] 2) The working tube of the gas lift valve is a mixing channel for high-pressure gas and well fluid. When gas lift is not implemented, the flow velocity in the center of the working tube is the fastest, and the flow velocity along the pipe wall is the lowest. Since the outlet of the gas lift valve working tube is at a 90-degree angle to the flow direction of the fluid in the oil pipe, when the gas lift gas enters the working tube from the annulus through the working tube, it will pass through the low-speed area, the central high-speed area, and then to the low-speed area on the opposite pipe wall. The high-pressure gas forms turbulence locally, and the gas lift efficiency is low.

[0006] 3) In the design of process parameters for conventional gas lift devices, multi-point gas injection should be avoided as much as possible, because this will reduce the gas lift efficiency. At the same time, the injection pressure, injection volume and drainage volume will fluctuate violently. Even when the formation pressure drops to a certain level, a "short circuit" will be formed, causing the injected gas to circulate in the wellbore, resulting in ineffective gas lift.

[0007] 2. Scaling precipitation: During the gas lift process, if the concentration of calcium and magnesium ions in the formation water is high, and the downhole fluid contains CO2 and H2S, the tubing will be scaled with a high probability. The main reason is that the temperature rises and the pressure drops during gas lift, which breaks the ion balance of the solution and causes scaling precipitation. The poor downhole conditions are the primary cause of gas lift process failures. Due to the poor downhole conditions of gas wells, the scaling is severe and the corrosion is strong, which often leads to scaling and blockage of gas lift valves, tubing, working cylinders, etc.

[0008] Scaling in gas wells seriously affects gas well production. The main solution is acid washing and replacement of tubing. MXX210 well has been in gas lift drainage production for less than a year since January 2022. The wellbore is frequently blocked. It is mainly unblocked by pumping inorganic acid + organic unblocking agent. So far, a total of 11 blockages have occurred (13 times of acid unblocking). A total of 25.2 cubic meters of organic unblocking agent, 40 cubic meters of hydrochloric acid, and 137 cubic meters of CT4-12B inorganic acid unblocking agent have been pumped. After acidification, the blockage can be removed and normal drainage production can be restored. However, the effective period of acid unblocking is shortening. The current unblocking frequency is once every 13 days to half a month, which is relatively high (usually once every six months or a year), resulting in a sharp increase in production and operation costs. Alternatively, a separate filling pipeline can be set up outside the oil pipe to fill descaling agents, antiscaling agents or scale inhibitors to prevent scale, but the filling channel construction is complicated and the one-time investment cost is high; or it can be added together with the high-pressure gas through the oil casing annulus. In this case, the filling effect is not obvious. The flow direction of the filled chemical agent is at a 90-degree angle to the flow direction of the liquid in the oil pipe. Most of it is brought to the ground with the well fluid. The descaling agents and scale inhibitors acting on the oil pipe wall are very few, resulting in an insignificant anti-scaling effect. Replacing the tubing, pickling, or filling chemicals through the pipeline all require high costs. During gas lift, the downward injection of gas injection is unstable and inefficient. Summary of the invention

[0009] The present invention aims to solve the deficiencies of the prior art and to provide a constant-speed gas lift device for preventing scaling in high-temperature wells. By adopting this solution, the flow direction of high-pressure gas is almost consistent with the flow direction of fluid in the wellbore, and the high-pressure gas transfers kinetic energy to the liquid flowing at a low speed along the pipe wall, thereby reducing liquid slippage and improving gas lift efficiency; and while improving gas lift stability and efficiency, it prevents scaling of gas wells, reduces production costs, and supports efficient development of gas wells.

[0010] The present invention is achieved through the following technical solutions:

[0011] A constant speed gas lift device for preventing scaling in high temperature wells, comprising:

[0012] An anti-scaling gas lift flow device and a constant speed gas lift flow device are respectively connected in series on the oil pipe;

[0013] The anti-fouling gas lift flow device comprises a first cylinder, both ends of which are open and connected to the oil pipe; a plurality of first gas lift injection channels are opened on the circumferential side wall of the first cylinder, and both ends of the first gas lift injection channels respectively penetrate the inner wall and the outer wall of the first cylinder; from the outer end to the inner end of the first gas lift injection channel, the first gas lift injection channel is inclined in the direction of gas-liquid flow; each of the first gas lift injection channels is also connected to an anti-fouling agent channel opened on the first cylinder;

[0014] The constant speed gas lift flow device includes a second cylinder, both ends of which are open and connected to the oil pipe; a plurality of second gas lift injection channels are opened on the circumferential side wall of the second cylinder, and both ends of the second gas lift injection channels respectively pass through the inner wall and the outer wall of the second cylinder; from the outer end to the inner end of the second gas lift injection channel, the second gas lift injection channel is inclined in the direction of well fluid flow; along its own length direction, the second gas lift injection channel includes a second Rafale pipe section.

[0015] In a further solution, the first gas lift injection channel includes a first Rafale pipe section along its length direction; the anti-scaling agent channel is connected to the roar channel in the middle of the first Rafale pipe section.

[0016] In a further embodiment, the first cylinder outer side wall is provided with an anti-scaling agent pipeline and a plurality of annular pipelines arranged in an annular direction, and the plurality of annular pipelines are sequentially spaced and distributed along the axis direction of the first cylinder; the anti-scaling agent pipeline sequentially passes through each of the annular pipelines and is connected to the interior of each of the annular pipelines;

[0017] Each of the antiscalant passages is communicated with the annular pipe at a respective position.

[0018] In a further embodiment, a plurality of the first gas lift and gas injection channels are distributed in a spiral shape in the axial direction of the first cylinder.

[0019] In a further solution, the first cylinder includes a plurality of first rings, and the plurality of first rings are coaxially spliced ​​in sequence.

[0020] In a further embodiment, a plurality of the second gas lift and gas injection channels are distributed in a spiral shape in the axial direction of the second cylinder.

[0021] In a further solution, the second cylinder includes a plurality of second rings, and the plurality of second rings are coaxially spliced ​​in sequence.

[0022] In a further embodiment, the anti-fouling gas lift flow device is located below the constant speed gas lift flow device.

[0023] In a further solution, the anti-scaling gas lift flow device is located above the completion packer, and an anti-scaling agent injection device is provided between the completion packer and the anti-scaling gas lift flow device;

[0024] The anti-scaling gas lift flow device is provided with an anti-scaling agent pipeline connected with a plurality of anti-scaling agent channels, the anti-scaling agent pipeline is connected with the anti-scaling agent filling device; and the end of the anti-scaling agent pipeline is provided with a filtering device.

[0025] A further solution further comprises a gas injection device, wherein the gas injection device is used to provide high-pressure gas to each of the first gas lift gas injection channel and the second gas lift gas injection channel.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] 1. The present invention provides a constant speed gas lift device for preventing scaling in high temperature wells. The flow direction of high pressure gas is almost consistent with the flow direction of fluid in the wellbore. The high pressure gas transfers kinetic energy to the liquid flowing at a low speed along the pipe wall, thereby reducing liquid slippage and improving gas lift efficiency. The Lafarge nozzle design can significantly improve the flow state. The high pressure gas flow in the nozzle is a critical flow, which does not change with the change of wellhead pressure. Its flow rate is constant, which further improves the gas lift efficiency, and the gas-liquid mixing is more uniform, and the drainage efficiency is higher.

[0028] 2. The present invention provides a constant speed gas lift equipment for preventing scaling in high temperature wells, wherein the constant speed gas lift flow device deploys high-pressure gas injection holes through staggered spirals to prevent erosion of the inner wall of the flow device by high-pressure gas when the holes are evenly arranged in the radial direction. The formed annular erosion zone will reduce the tensile strength of the tool. Even under the same material and process conditions, such staggered spiral deployment can significantly reduce erosion; in addition, it is also beneficial to reduce the impact of turbulence in the gas-liquid mixing zone, thereby improving the water-carrying efficiency of gas lift.

[0029] 3. The present invention provides a constant speed gas lift device for preventing scaling in high temperature wells. The constant speed gas lift flow device has also made improvements in anti-erosion. Usually, the flow center speed is fast and the flow speed along the pipe wall is low. The present invention makes the flow speed of the pipe wall high, which can significantly reduce the deposition of scale in high temperature wells prone to scaling. At the same time, the fast flow rate can also make some scale detach from the pipe wall.

[0030] 4. The present invention provides a constant speed gas lift equipment for preventing scaling in high temperature wells. The anti-scaling gas lift flow device introduces high-pressure gas through a plurality of Rafale tube sections in the gas lift injection channels, and can automatically suck chemicals into the Rafale tube sections at the low-pressure end, and spray the chemicals into the well fluid through a similar nozzle, thereby achieving sufficient mixing of the chemicals, gas and well fluid to improve the anti-scaling efficiency.

[0031] 5. The present invention provides a constant speed gas lift equipment for preventing scaling in high temperature wells. The anti-scaling gas lift flow device is spirally distributed in the axial direction through a plurality of gas lift injection channels. The staggered spiral divisions help the absorbed chemicals to act over a longer distance, thereby preventing the formation or reduction of scaling in the scaling section, saving chemicals, and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative work. In the drawings:

[0033] Figure 1 This is a principle diagram of the gas lift drainage gas production process in the prior art;

[0034] Figure 2 It is a schematic diagram of a downhole pipe string for a gas lift drainage and gas production process in the prior art;

[0035] Figure 3 It is a cross-sectional view of a gas lift valve working cylinder in the prior art;

[0036] Figure 4 A schematic diagram of a well completion device for the anti-scaling constant-speed gas lift provided by the present invention;

[0037] Figure 5 A schematic diagram of the structure of a constant speed gas lift flow device provided by the present invention;

[0038] Figure 6 A cross-sectional view of a single second collar provided for the present invention;

[0039] Figure 7 A side view of a single second collar provided for the present invention;

[0040] Figure 8 A schematic structural diagram of a second gas lift gas injection channel provided by the present invention;

[0041] Fig. 9 A schematic diagram of the structure of the anti-fouling gas lift flow device provided by the present invention;

[0042] Fig.10 A cross-sectional view of the anti-fouling gas lift flow device provided by the present invention;

[0043] Fig.11 A cross-sectional view of a single first sleeve provided by the present invention;

[0044] Fig.12 A side view of a single first sleeve provided for the present invention;

[0045] Fig.13 This is a schematic structural diagram of the first gas lift gas injection channel provided by the present invention.

[0046] Fig.14 The production situation analysis diagram under different gas injection conditions provided by the present invention;

[0047] Fig.15 The flow analysis diagram of the nozzle with friction provided by the present invention;

[0048] Fig.16 The internal flow diagram of the Rafale nozzle provided by the present invention;

[0049] Fig.17 A total pressure distribution diagram provided by the present invention;

[0050] Fig.18 The velocity distribution diagram provided by the present invention (the maximum flow velocity at the flared part is 6.5 Mach, and the Mach number at the throat is 1);

[0051] Fig.19 A schematic diagram of the determined gas injection pressure provided by the present invention.

[0052] Marks and corresponding parts names in the attached drawings:

[0053] 1-anti-scaling gas lift flow device, 101-first cylinder, 1011-first sleeve ring, 102-first gas lift gas injection channel, 103-anti-scaling agent channel, 104-first Rafale pipe section, 105-anti-scaling agent pipeline, 106-annular pipeline, 2-constant speed gas lift flow device, 201-second cylinder, 2011-second sleeve ring, 202-second gas lift gas injection channel, 203-second Rafale pipe section, 3-oil pipe, 4-well completion packer. DETAILED DESCRIPTION

[0054] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with embodiments and drawings. The exemplary embodiments of the present invention and their description are only used to explain the present invention and are not intended to limit the present invention.

[0055] Embodiment 1:

[0056] This embodiment 1 provides a constant speed gas lift flow device 2, such as Figure 1-Figure 8 As shown, including:

[0057] A second cylinder 201 connected in series in the middle of the oil pipe 3, wherein both ends of the second cylinder 201 are open and communicated with the oil pipe 3;

[0058] A plurality of second gas lift gas injection channels 202 are formed on the circumferential side wall of the second cylinder 201, and two ends of the second gas lift gas injection channels 202 respectively penetrate the inner wall and the outer wall of the second cylinder 201;

[0059] From the outer end to the inner end of the second gas lift gas injection channel 202, the second gas lift gas injection channel 202 is inclined toward the direction of well fluid flow;

[0060] Along its length direction, the second gas lift gas injection channel 202 includes a second Rafale pipe section 203 .

[0061] In the prior art, the gas lift process is an artificial lift process that injects high-pressure gas into the oil pipe 3 through a high-pressure gas source to reduce the flow pressure gradient above the gas injection point, reduce the slip loss during the lifting process, discharge the bottom hole liquid, increase the production pressure difference, and restore or improve the production capacity of the gas well. Compared with other processes, the gas lift process has great advantages, it has a wide range of applications, low failure rate, and a long maintenance-free period. Figure 1 and Figure 2 As shown, let AA be the static liquid level position after the gas well is flooded. When high-pressure gas is injected from the casing, the high-pressure gas causes the casing liquid level to drop and the oil pipe 3 liquid level to rise. When the casing liquid level drops to the inlet BB of the first gas lift valve, the gas lift valve is opened by the pressure of the high-pressure gas, and the high-pressure gas enters the oil pipe 3 through the gas lift valve. Under the action of the gas expansion force, the liquid above the BB interface is lifted to the ground. At the same time, due to the large amount of high-pressure gas entering the oil pipe 3, the casing pressure is reduced. When the casing pressure drops to the closing pressure of the gas lift valve, the first gas lift valve is closed. Then, the high-pressure gas forces the casing liquid level to drop and the oil pipe 3 liquid level to rise. When the casing liquid level drops to the inlet CC of the second gas lift valve, the second gas lift valve is opened by the high-pressure gas, and the liquid above the CC-BB interface is lifted to the ground. In this way, the liquid level in the oil pipe 3 is continuously lowered until the gas well resumes production. In the process of process parameter design, the depth, opening pressure and other parameters are designed from the first gas lift valve above, and then the second gas lift valve, and then proceed downwards. Therefore, through the above-mentioned gas lift valve gas production principle, the following will occur: 1) the downward-flowing injected gas will cause a large amount of energy loss, and the gas lift efficiency and gas lift stability will be greatly reduced; 2) when the gas lift injected gas passes through the annulus into the interior of the working cylinder, it will successively pass through the low-speed area, the central high-speed area, and then to the low-speed area of ​​the opposite pipe wall. The high-pressure gas will form turbulence locally, and the gas lift efficiency is low; 3) when the formation pressure drops to a certain level, a "short circuit" is formed, causing the injected gas to circulate in the wellbore, resulting in the ineffectiveness of gas lift and other problems. Therefore, the present invention provides a constant-speed gas lift flow device 2 and its equipment. By adopting this scheme, the flow direction of the high-pressure gas is almost consistent with the flow direction of the fluid in the wellbore. The high-pressure gas transfers kinetic energy to the liquid flowing at a low speed along the pipe wall, thereby reducing liquid slippage and improving gas lift efficiency. The injected gas can reach critical flow, and the flow is in a constant speed state, which is convenient for uniform liquid discharge and more conducive to improving liquid discharge efficiency. In addition, the present invention has also made improvements in anti-erosion. Usually, the flow center speed is fast and the flow velocity along the pipe wall is low. The present invention makes the flow velocity of the pipe wall high, which can significantly reduce the deposition of scale for high-temperature wells prone to scaling. At the same time, the fast flow rate can also make some scale detach from the pipe wall. The Rafale nozzle design can significantly improve the flow state, make the gas-liquid mixing more uniform, and improve the drainage efficiency.

[0062] In the specific scheme, it includes a second cylinder 201 connected in series in the middle of the oil pipe 3, the second cylinder 201 and the oil pipe 3 are coaxially arranged, and both ends are connected to the oil pipe 3; an inclined second gas lift injection channel 202 is arranged on the side wall of the second cylinder 201, and the second gas lift injection channel 202 is inclined in the direction of well fluid flow, so that an external high-pressure gas source can inject high-pressure gas into the interior through the second gas lift injection channel 202, and the injection direction of the high-pressure gas is the same as the flow direction of the well fluid, so that the high-pressure gas can transfer kinetic energy to the liquid flowing at a low speed along the pipe wall, thereby reducing liquid slippage and improving gas lift efficiency. Secondly, since the second gas lift injection channel 202 includes a second Rafale pipe section 203, using the Rafale nozzle principle, its outlet pressure is only related to the external transmission pressure; by controlling the external transmission pressure, the injected gas reaches the critical flow velocity. Since the maximum speed in the constant speed gas lift flow device 2 reaches the critical flow velocity, its flow rate is the critical flow rate and it is impossible to continue to increase. Therefore, other natural gas (total gas injection volume minus total critical flow rate) naturally enters the next level flow device, thereby continuing to increase the gas lift depth, forming a relay lift, and improving the gas lift efficiency. In a word: the diameter of the valve hole of the gas lift valve on the conventional gas lift string is much larger than the nozzle size of the constant speed gas lift device. Its flow is not critical flow rate. The pressure at the valve is affected by the wellhead back pressure and fluctuates with the wellhead pressure fluctuation. The gas volume passing through the first gas lift valve also changes. However, the high-pressure gas flow in the nozzle of the designed constant speed gas lift device is critical flow, which does not change with the change of wellhead pressure and its flow rate is constant. Therefore, it flows through the critical constant speed and the speed does not change with the wellhead pressure, which further improves the gas lift efficiency. Figure 6 As shown in FIG. 1 , a schematic diagram of a high-pressure gas injection flow channel of a constant-speed gas lift flow device 2 is shown. The principle is that after the high-pressure gas passes through the large bypass channel ① and then enters the extremely narrow channel ②, part of its potential energy is converted into kinetic energy, so that the speed of the high-pressure gas reaches or approaches the speed of sound. Its speed is constant and does not change with the change of downstream pressure. After flowing out from ③, it mixes with the well fluid. Generally, for natural gas with a relative density of 0.6, when P③ / P①<0.546, that is, when the ratio of downstream pressure to upstream pressure is less than 0.546, the gas reaches the critical flow rate. The shape of the flow channel is obtained through the critical flow rate and the Lafarge spray pipe theory combined with the experimental device.

[0063] In addition, the present invention has also made improvements in anti-erosion. In conventional gas lift processes, the flow center speed is usually fast and the flow velocity along the pipe wall is low. In the present invention, the high-pressure gas can transfer kinetic energy to the liquid flowing at a low speed along the pipe wall, so that the flow velocity of the pipe wall is high. For high-temperature wells that are prone to scaling, the scale deposition can be significantly reduced. At the same time, the fast flow rate can also make some scale detach from the pipe wall. The Rafale nozzle design can significantly improve the flow state, make the gas-liquid mixing more uniform, and improve the drainage efficiency.

[0064] In order to reduce turbulence and erosion, several of the second gas lift injection channels 202 are distributed in a spiral in the axial direction of the second cylinder 201. In this solution, several of the second gas lift injection channels 202 are distributed in a spiral as a whole, forming a complete spiral hole arrangement. The advantage is to prevent the erosion of the inner wall of the flow device by high-pressure gas when the holes are evenly arranged in the radial direction, and the formed annular erosion zone will reduce the tensile strength of the tool. Even under the same material and process conditions, such staggered spiral deployment can significantly reduce erosion; in addition, the deployment of high-pressure gas injection holes by staggered spirals is also beneficial to reduce the impact of turbulence in the gas-liquid mixing zone, thereby improving the water-carrying efficiency of gas lift.

[0065] In order to realize the length selection of the second cylinder 201 and quick splicing, the second cylinder 201 includes a plurality of second rings 2011, and the plurality of second rings 2011 are coaxially spliced ​​in sequence. The present invention can design the specific number of holes and the aperture according to the gas injection amount and the gas injection pressure, so that the gas injection in each hole can reach the critical flow, at which time the change of the input pressure will not cause the change of the discharge amount, and the flow is in a constant speed state; wherein, as shown in the figure, there are 6 second rings 2011, and 4 to 6 second gas lift gas injection channels 202 are arranged in each second ring 2011, preferably 4 second gas lift gas injection channels 202, and the 4 second gas lift gas injection channels 202 are gradually increased in a spiral of 90 degrees in sequence, and between adjacent second rings 2011, each second ring 2011 and the previous second ring 2011 are spirally rotated 15 to 30 degrees, preferably 15 degrees, so as to form a complete spiral hole arrangement.

[0066] In order to provide an outlet end face for the injected high-pressure gas and allow the high-pressure gas to enter along the flow direction of the well fluid, the inner side of the second collar 2011 includes a large diameter section and a small diameter section connected to each other, and the end face between the large diameter section and the small diameter section is a spiral end face arranged along the axial direction of the second collar 2011, and the inner end of each of the second gas lift injection channels 202 on the second collar 2011 passes through the spiral end face.

[0067] In order not to affect the flow rate of the high-pressure gas and allow the high-pressure gas to smoothly enter the internal flow channel along its axial direction, the spiral end surface is inclined from the large diameter section side to the small diameter section side and is perpendicular to the axis of the second gas lift injection channel 202.

[0068] As a redundancy solution, adjacent second rings 2011 are detachably connected.

[0069] As a splicing method between several second rings 2011, the large diameter section and the small diameter section are respectively located at the outlet end and the inlet end of the second ring 2011, and the outer side of the inlet end of the second ring 2011 is provided with a reduced diameter section, and the outer diameter of the reduced diameter section is adapted to the inner diameter of the outlet end. Adjacent second rings 2011, and between the second ring 2011 and the oil pipe 3 are connected with the outlet end through the reduced diameter section for socket connection or thread connection. Of course, in order to make the connection node more stable, other fixed connection methods such as welding can also be used.

[0070] Embodiment 2:

[0071] This embodiment 2 provides an anti-fouling gas lift flow device 1, such as Figure 4 , Figure 9-13 As shown, including:

[0072] A first cylinder 101 connected in series in the middle of the oil pipe 3, wherein both ends of the first cylinder 101 are open and communicated with the oil pipe 3;

[0073] A plurality of first gas lift gas injection channels 102 are formed on the circumferential side wall of the first cylinder 101, and two ends of the first gas lift gas injection channels 102 respectively penetrate the inner wall and the outer wall of the first cylinder 101;

[0074] From the outer end to the inner end of the first gas lift gas injection channel 102, the first gas lift gas injection channel 102 is inclined toward the direction of gas-liquid flow;

[0075] Each of the first gas lift injection channels 102 is also connected to an anti-scaling agent channel 103 opened on the first cylinder 101 .

[0076] Compared with the prior art, the flow direction of the injected chemical agent is at a 90-degree angle to the flow direction of the liquid in the oil pipe 3, and most of it is brought to the surface with the well fluid. Very few descaling agents and scale inhibitors act on the wall of the oil pipe 3, resulting in an unclear anti-scaling effect. Replacing the tubing string, pickling, or injecting chemicals through the pipeline all require relatively high costs. During gas lift, the downward injection of gas is unstable and inefficient. The present invention provides an anti-scaling gas lift flow device 1 and its equipment. By adopting this solution, gas lift stability and efficiency can be improved while preventing scaling of gas wells, reducing production costs and supporting efficient development of gas wells.

[0077] In the specific scheme, it includes a first cylinder 101 connected in series in the middle of the oil pipe 3, the first cylinder 101 and the oil pipe 3 are coaxially arranged, and both ends are connected to the oil pipe 3; an inclined first gas lift injection channel 102 is arranged on the side wall of the first cylinder 101, and the first gas lift injection channel 102 is inclined in the direction of well fluid flow, so that an external high-pressure gas source can inject high-pressure gas into the interior through the first gas lift injection channel 102, and the injection direction of the high-pressure gas is the same as the flow direction of the well fluid, so that the high-pressure gas can transfer kinetic energy to the liquid flowing at a low speed along the pipe wall, thereby reducing liquid slippage and improving gas lift efficiency. In addition, there are several anti-scaling agent channels 103 on the side wall of the first cylinder 101. Through the several anti-scaling agent channels 103, it is convenient to input chemical agents that play a role in scale inhibition or descaling into the several first gas lift injection channels 102. The first gas lift injection channels 102 drive the chemical agents to enter the interior and mix with the incoming liquid through the high-pressure gas source output by themselves, and the entry direction of the chemical agents is also inclined in the direction of the well fluid flow. At this time, the flow velocity of the pipe wall is high, and it is easier to distribute the chemical agents to the pipe wall, so that part of the scale is separated from the pipe wall, playing a role in scale inhibition or descaling, and achieving the purpose of scale prevention and control. Of course, according to the scaling situation, two or three types of descaling agents, scale inhibitors or anti-scaling agents can also be added at the same time to achieve the purpose of joint scaling prevention and control. Before mixing, it is necessary to do a compatibility test of the agents and conduct a comprehensive performance evaluation.

[0078] In order to make the chemical agent and the well fluid mix more evenly and automatically absorb the chemical agent by pressure to improve the anti-scaling effect, the first gas lift injection channel 102 includes a first Rafael pipe section 104 along its length direction; the anti-scaling agent channel 103 is connected to the roar channel in the middle of the first Rafael pipe section 104. In this solution, the first gas lift injection channel 102 includes the first Rafael pipe section 104, and uses the Rafael nozzle principle, and its outlet pressure is only related to the external transmission pressure; Fig.11 As shown in the figure, it is a schematic diagram of the Lafarge principle device, which consists of a high-pressure air inlet end ① (the junction of ① and ② can be regarded as a nozzle), ② is a roar channel, ③ is a diffusion section, and ④ is a low-pressure end (i.e., the suction end of the chemical agent). The high-pressure gas flows at a high speed, and the chemical agent is sucked in from the low-pressure end, and the chemical agent is gathered and mixed in the roar channel ②, and mixed more evenly in the diffusion section ③, and then mixed with the well fluid through the outlet of ③, that is, the high-speed kinetic energy of the high-pressure gas is partially converted into the potential energy of the well fluid. At the same time, due to the mixing of the high-pressure gas and the liquid, the pressure gradient of the liquid is also reduced. In addition, the inhaled chemical agent contacts with the well wall to play a role in scale inhibition or descaling. Of course, the anti-scaling agent can also be inhaled, thereby achieving the purpose of scale prevention and control.

[0079] The gas in its flow channel is in a non-critical flow state. Due to the need to absorb chemicals, its flow channels should be at least more than 36, and its roar channel should be determined according to the dosage of the injected chemical, the injection pressure at the location of the device, the injection volume and temperature; the number of its inhaled chemical ends is determined by the continuous injection amount and the type of chemical. Usually, the gas lift design of 4mm aperture is equivalent to 16 special Rafael nozzles, 5mm aperture is equivalent to 25 special Rafael nozzles, 6mm aperture is equivalent to 36 special Rafael nozzles, 7mm aperture is equivalent to 49 special Rafael nozzles, and 8mm aperture is equivalent to 64 special Rafael nozzles. The diameter of each nozzle is usually 1-1.2mm, which needs to be determined according to the dosage of chemical agents. If the design size is too large, the daily consumption of chemical agents will be large. If it is too small, the anti-scaling and scaling effects will be poor. Of course, it is closely related to the performance of descaling agents, scale inhibitors or scale inhibitors. Good performance means less dosage, and of course the nozzle diameter is small. If necessary, some nozzles can be blind-plugged with low-pressure chemical suction end.

[0080] In order to evenly provide corresponding chemical agents to each anti-scaling agent channel 103, the outer wall of the first cylinder 101 is provided with an anti-scaling agent pipeline 105 and a plurality of annular pipelines 106 arranged in an annular direction, and the plurality of annular pipelines 106 are distributed in sequence along the axial direction of the first cylinder 101 at intervals; the anti-scaling agent pipeline 105 passes through each of the annular pipelines 106 in sequence and is connected with the interior of each of the annular pipelines 106; each of the anti-scaling agent channels 103 is connected with the annular pipelines 106 at their respective positions. In this scheme, the anti-scaling agent pipeline 105 is fixed on the outer wall of the first cylinder 101, and one end of the pipeline of the anti-scaling agent pipeline 105 is connected to a plurality of annular pipelines 106, and the other end is extended to a position near the packer, and the pipeline is fixed to the oil pipe 3 by a binding band or a wire tie; in this way, through the collection of multiple air injection holes, the chemical agent suction end is assembled into a separate liquid suction pipeline at the lower end of the anti-scaling gas lift flow device 1, and on the anti-scaling gas lift flow device 1, all the suction ports are also integrated into a channel through the annular pipeline and connected to the lower end suction chemical agent pipeline.

[0081] In order to provide a longer action distance for the chemical agent, the plurality of the first gas lift injection channels 102 are spirally distributed in the axial direction of the first cylinder 101. In this solution, the plurality of the first gas lift injection channels 102 are spirally distributed in the axial direction, and the staggered spiral divisions help the absorbed chemical agent to act on a longer distance, thereby preventing the formation or reduction of scale in the scaling section, and also saving chemical agents, thereby reducing costs.

[0082] In order to select the length of the first cylinder 101 and quickly splice it, the first cylinder 101 includes a plurality of first rings 1011, and the plurality of first rings 1011 are coaxially spliced ​​in sequence.

[0083] In order to provide an outlet end face for the injected high-pressure gas and allow the high-pressure gas to enter along the flow direction of the well fluid, the inner side of the first collar 1011 includes a large diameter section and a small diameter section connected to each other, and the end face between the large diameter section and the small diameter section is a spiral end face arranged along the axial direction of the first collar 1011, and the inner end of each of the first gas lift injection channels 102 on the first collar 1011 passes through the spiral end face.

[0084] As a splicing method between several first sleeve rings 1011, the large diameter section and the small diameter section are respectively located at the outlet and inlet ends of the first sleeve ring 1011, and the outer side of the inlet end of the first sleeve ring 1011 is provided with a reduced diameter section, and the outer diameter of the reduced diameter section is adapted to the inner diameter of the outlet end; the adjacent first sleeve rings 1011, the first sleeve ring 1011 and the oil pipe 3 are all connected with the outlet end through the reduced diameter section for socket connection or thread connection. Of course, in order to make the connection node more stable, other fixed connection methods such as welding can also be used.

[0085] Embodiment 3:

[0086] This embodiment 3 is further optimized on the basis of embodiment 1 and embodiment 2. Figure 4 As shown, a constant speed gas lift equipment for preventing scaling in high temperature wells is also provided, comprising an anti-scaling gas lift flow device 1 and a constant speed gas lift flow device 2 which are sequentially connected in series on an oil pipe 3 from bottom to top, wherein the anti-scaling gas lift flow device 1 is the anti-scaling gas lift flow device 1 in Example 2, and the constant speed gas lift flow device 2 is the constant speed gas lift flow device 2 in Example 1.

[0087] The present invention adopts a two-stage multi-point gas injection method to implement gas lift. A constant-speed gas lift flow device 2 is used in the upper first stage. The flow mode of the injected gas in the flow channel of the gas lift device is critical flow, and its outlet pressure is only related to the external transmission pressure. Since the maximum speed in the upper constant-speed gas lift flow device 2 reaches the critical flow rate, its flow rate is the critical flow rate and it is impossible to continue to increase. Therefore, other natural gas (total gas injection volume minus total critical flow rate) naturally enters the next-stage flow device, thereby continuing to increase the gas lift depth, forming a relay lift, and improving the gas lift efficiency. In a word: the valve hole diameter of the gas lift valve on the conventional gas lift column is much larger than the nozzle size of the constant-speed gas lift device. Its flow is non-critical flow rate. The pressure at the valve is affected by the wellhead back pressure and fluctuates with the wellhead pressure fluctuation. The gas volume passing through the first gas lift valve also changes. However, in the designed constant-speed gas lift device, the high-pressure gas flow in its nozzle is critical flow, which does not change with the change of the wellhead pressure, and its flow rate is constant.

[0088] The second-stage anti-scaling gas lift device below has a high-pressure gas injection channel and an anti-scaling agent injection channel. The flow channel of the Lafarge nozzle (with a low-pressure inlet end) optimized by the Venturi experimental device is also used as the gas lift injection channel. The device can rely on the injection of high-pressure gas to continuously and evenly inhale the chemical agent from the low-pressure inlet end, further reducing the frequency of ground descaling construction, reducing the number of descaling times, and reducing costs, thereby achieving the purpose of anti-scaling and descaling.

[0089] The process parameter design of this device is different from all the gas lift process parameter design methods currently disclosed. First, the parameters of the second-stage anti-scaling and descaling gas lift device are designed. The gas injection volume of the second stage does not exceed 2 / 3 to 3 / 4 of the total well gas injection volume. The gas injection pressure is determined according to the liquid discharge volume and the gas injection depth, or the gas injection depth is determined according to the liquid discharge volume and the gas injection pressure. Then, the flow channel size and the number of holes of the second-stage anti-scaling and descaling gas lift flow device are determined according to the injection pressure, gas injection volume, the temperature of the gas injection point, and the daily injection chemical dosage. Finally, the first-stage constant-speed gas lift flow device 2 is designed. The gas injection aperture and number are designed according to the critical flow formula with 1 / 3 to 1 / 4 of the total well gas injection volume. Usually, the gas injection aperture is preferably 1 mm. The well entry depth of the first-stage constant-speed gas lift flow device 2 is designed in combination with the pipe flow formula. At this depth, the high-pressure gas is in a critical flow state.

[0090] Generally, for natural gas with a relative density of 0.6, when P③ / P①<0.546, that is, when the ratio of downstream pressure to upstream pressure is less than 0.546, the gas reaches the critical flow rate. The shape of the flow channel is obtained through the critical flow rate and Laval nozzle theory combined with the experimental device. Figure 14-Figure 19 As shown in the following design method:

[0091] 1. Analysis of gas lift injection volume, drainage volume, and bottom hole flow pressure;

[0092] According to the possible production situation of the gas well, the water production, gas production, pressure and other parameters under different gas injection rates are analyzed and calculated. Fig.14 .

[0093] 2. Design the dimensions and working parameters of the Rafale tube;

[0094] Due to friction, the actual nozzle performance is slightly different from that calculated using the isentropic flow relationship. However, because the deviation is small, when designing a nozzle, it is generally calculated using the isentropic flow formula and then corrected using two experimentally determined coefficients, the nozzle efficiency and the flow coefficient.

[0095] (1) Nozzle efficiency

[0096] Fig.15represents an actual nozzle flow with friction. The stagnation parameter of the nozzle inlet gas is known. When the gas flows through the nozzle, in the absence of friction, it should expand isentropically until the pressure on the outlet cross section is The kinetic energy of , where the angle code "lx" represents the ideal value. However, in practice, only kinetic energy, where the angle code "sj" represents the actual value.

[0097]

[0098] The value of nozzle efficiency η is mainly determined by the properties of the boundary layer. For larger nozzles, the boundary layer thickness is much smaller than the pipe diameter, and η is close to 1. For very small nozzles, the boundary layer is relatively thick, so η may be significantly reduced. For a well-designed nozzle with a straight axis, when it works at the design pressure ratio and large Re number, η = 0.94 ~ 0.99.

[0099] (2) Flow coefficient

[0100] The flow coefficient of the nozzle is the ratio of the actual nozzle flow to the flow calculated according to isentropic flow under the same inlet and outlet parameters, that is,

[0101]

[0102] Therefore, the actual nozzle flow rate is

[0103]

[0104] When the nozzle is full of subsonic flow, the actual flow rate can be calculated from the conditions at the nozzle outlet. If the flow velocity on the smallest cross section of the nozzle is equal to supersonic, then the actual flow rate of the nozzle has reached the maximum value, that is,

[0105]

[0106] For a well-designed nozzle with a straight axis, when the minimum cross-section is Re>106, C G ≈0.99CG. But when Re is low, C G Will be significantly reduced. Fig.16 It means using a Rafale nozzle to provide supersonic airflow to the pipe.

[0107] The flow is adiabatic and there is friction. The airflow at the throat has reached the critical state, so the actual flow rate is

[0108]

[0109] The above formula shows that if the throat area At of the nozzle and the cross-sectional area A of the pipe are known, when the stagnation pressure p0 before the nozzle is measured, the Ma number on the A section can be calculated based on the flow coefficient.

[0110] The Lafayette nozzle and its working parameters are designed by modifying the flow coefficient and nozzle efficiency η.

[0111] (3) Digital simulation design of Lafarge tube and working parameters;

[0112] Numerical simulations were performed on nozzles of various geometric structures under various flow parameters. The optimized nozzle design can obtain a hypersonic airflow with a Mach number of 6.5. The numerical simulation results show that the optimized nozzle design can obtain a hypersonic airflow. The size and operating parameters of the nozzle are thus designed.

[0113] 3. Determine the anti-scaling gas lift parameters;

[0114] According to the analysis of gas lift injection volume, displacement, and bottom hole flow pressure, combined with the Lafarge nozzle design and working parameter analysis, the nozzle inlet pressure and gas injection volume are obtained. Thus, the required gas injection pressure on the ground is obtained by calculating the gas injection pressure profile from the bottom of the well to the wellhead, see Fig.19 .

[0115] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method 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 in the scope of protection of the present invention.

Claims

1. A constant speed gas lift device for preventing scaling in high temperature wells, characterized in that: include: An anti-scaling gas lift flow device (1) and a constant speed gas lift flow device (2) respectively connected in series on an oil pipe (3); The anti-fouling gas lift flow device (1) comprises a first cylinder (101), both ends of the first cylinder (101) are open and connected to the oil pipe; a plurality of first gas lift injection channels (102) are opened on the circumferential side wall of the first cylinder (101), and both ends of the first gas lift injection channels (102) respectively penetrate the inner wall and the outer wall of the first cylinder (101); from the outer end to the inner end of the first gas lift injection channel (102), the first gas lift injection channel (102) is inclined in the direction of gas-liquid flow; each of the first gas lift injection channels (102) is also connected to an anti-fouling agent channel (103) opened on the first cylinder (101); The constant speed gas lift flow device (2) comprises a second cylinder (201), both ends of which are open and connected to the oil pipe; a plurality of second gas lift injection channels (202) are opened on the circumferential side wall of the second cylinder (201), and both ends of the second gas lift injection channels (202) respectively pass through the inner wall and the outer wall of the second cylinder (201); from the outer end to the inner end of the second gas lift injection channel (202), the second gas lift injection channel (202) is inclined in the direction of well fluid flow; along its own length direction, the second gas lift injection channel (202) comprises a second Rafale pipe section (203).

2. A constant speed gas lift device for preventing scaling in high temperature wells according to claim 1, characterized in that: Along its length direction, the first gas lift injection channel (102) includes a first Rafale pipe section (104); the anti-scaling agent channel (103) is connected to the roar channel in the middle of the first Rafale pipe section (104).

3. The constant speed gas lift equipment for preventing scaling in high temperature wells according to claim 1, characterized in that: The outer wall of the first cylinder (101) is provided with an anti-scaling agent pipeline (105) and a plurality of annular pipelines (106) arranged in an annular direction, wherein the plurality of annular pipelines (106) are sequentially spaced and distributed along the axis direction of the first cylinder (101); the anti-scaling agent pipeline (105) sequentially passes through each of the annular pipelines (106) and is in communication with the interior of each of the annular pipelines (106); Each of the anti-scaling agent passages (103) is communicated with the annular pipe (106) at a respective position.

4. The constant speed gas lift equipment for preventing scaling in high temperature wells according to claim 1, characterized in that: The plurality of first gas lift gas injection channels (102) are distributed in a spiral shape in the axial direction of the first cylinder (101).

5. The constant speed gas lift equipment for preventing scaling in high temperature wells according to claim 1, characterized in that: The first cylinder (101) comprises a plurality of first rings (1011), and the plurality of first rings (1011) are coaxially spliced ​​in sequence.

6. The constant speed gas lift equipment for preventing scaling in high temperature wells according to claim 1, characterized in that: The plurality of second gas lift gas injection channels (202) are distributed in a spiral shape in the axial direction of the second cylinder (201).

7. The constant speed gas lift equipment for preventing scaling in high temperature wells according to claim 1, characterized in that: The second cylinder (201) comprises a plurality of second rings (2011), and the plurality of second rings (2011) are coaxially spliced ​​in sequence.

8. The constant speed gas lift equipment for preventing scaling in high temperature wells according to claim 1, characterized in that: The anti-fouling gas lift flow device (1) is located below the constant speed gas lift flow device (2).

9. The constant speed gas lift equipment for preventing scaling in high temperature wells according to claim 1, characterized in that: The anti-scaling gas lift flow device (1) is located above the completion packer (4), and an anti-scaling agent injection device is provided between the completion packer and the anti-scaling gas lift flow device (1); The anti-scaling gas lift flow device (1) is provided with an anti-scaling agent pipeline (105) connected to a plurality of anti-scaling agent channels (103); the anti-scaling agent pipeline (105) is connected to the anti-scaling agent filling device; and the end of the anti-scaling agent pipeline (105) is provided with a filtering device.

10. The constant speed gas lift equipment for preventing scaling in high temperature wells according to claim 1, characterized in that: It also includes a gas injection device, which is used to provide high-pressure gas to each of the first gas lift gas injection channel (102) and the second gas lift gas injection channel (202).

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