A downhole multi-stage spiral nested oil-water fine separation device

Abstract

The present disclosure relates to a downhole multi-stage spiral nested oil-water fine separation device; the device comprises a spiral settling module and a fine separation module; the spiral settling module utilizes a spiral flow channel to separate oil-water two-phase by cyclone layering, to make the central oil phase enter the upper oil pipe coupling from the oil phase outlet, and part of the water phase enters the coalescence plate below the settling separation area; the fine separation module performs secondary fine separation on the liquid phase containing a small amount of oil phase after separation by the spiral settling module, the separated oil phase is combined with the settled oil phase through the overflow pipe, and the separated water phase is discharged into the lower oil pipe coupling through the water phase outlet on the inverted cone. In the embodiment of the present disclosure, the coalescence unit comprising a plurality of coalescence plates is located inside the primary separation area, realizing the combination of cyclone, settling and coalescence in a small space, and the structure is simple and the energy loss is small, which is suitable for completing multi-stage fine separation of oil-water two-phase in the wellbore.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of oilfield downhole injection and production, in particular, to an oil-water fine separation device applied to the field of downhole oil-water separation. BACKGROUND

[0002] With the continuous deepening of oilfield exploitation, reducing production cost and improving production efficiency have gradually become an important means for oilfields to improve competitiveness. In the process of gradually popularizing and applying the same-well injection and production scheme, it is found that for high-yield liquid oil wells, most of the existing downhole oil-water separation equipment faces the problem of insufficient processing capacity, and too much water phase is lifted to the ground, which not only causes waste of resources, but also brings difficulties to downhole reinjection. In view of this problem, the skilled person has given a solution: patent number: CN201910438433.8, downhole multi-stage cyclone coalescence oil-water separation device, the disclosed literature content shows that the separation quality is improved by setting two-stage cyclone separation and increasing coalescer. However, this structure still has shortcomings: first, the flow channel arrangement, the light phase oil after the first-stage cyclone separation flows from the first-stage overflow pipe to the upper coupling, and the light phase oil after the second-stage cyclone separation enters the second-stage flow channel between the second-stage cyclone separation assembly and the coalescence device and the casing, and then enters the upper coupling from the first-stage flow channel between the first-stage cyclone separation assembly and the casing, the flow channel arrangement is complex, and the energy loss is large. Second, each part is directly connected in series, which occupies a large space and is limited by the narrow space in the downhole, which brings difficulties to popularization and application. SUMMARY

[0003] The present disclosure proposes a downhole multi-stage spiral nested oil-water fine separation device, which can solve the technical problems pointed out in the background art. The technical solution given by the present disclosure is that the oil phase medium under the action of two-stage fine cyclone separation is directly gathered with the oil phase separated by sedimentation through the overflow port and overflow pipe located in the center of the entire device, and then enters the oil pipe coupling together from the oil phase outlet. The structure is simple and the energy loss is small. In addition, the coalescence structure is arranged inside the first-stage separation area, which reduces the occupied space and realizes the combination of cyclone, sedimentation and coalescence in a narrow space.

[0004] The downhole separation assembly for the same-well injection and production well disclosed by the present disclosure, basic scheme 1: includes a spiral sedimentation module, which is unique in that:

[0005] The spiral sedimentation module includes an upper housing 102, a spiral flow channel end cover 103, a first-stage spiral flow channel 104, a coalescence housing 105, and a coalescence plate 106;

[0006] The lower end of the spiral flow channel end cover 103 is connected with the first spiral flow channel 104 through threads; the surface of the upper shell 102 is provided with a feeding hole 1021, and the lower end of the feeding hole 1021 is provided with threads for connecting with the outer threads of the lower shell 201;

[0007] The inner straight pipe section of the first spiral flow channel 104 is provided with a first spiral flow channel cavity 1042, and a spiral flow guide groove is arranged on the outer wall corresponding to the straight pipe section; a plurality of liquid inlet holes 1041 are arranged on the reduced diameter section of the first spiral flow channel 104, and the liquid inlet holes are communicated with the first spiral flow channel cavity; the reduced diameter section of the first spiral flow channel 104 is connected with the coalescence shell 105 through threads;

[0008] A plurality of coalescence plates 106 are connected with the coalescence shell 105 through threads and are stacked and arranged in the interior of the coalescence shell 105;

[0009] After the spiral flow channel end cover 103, the first spiral flow channel 104, the coalescence shell 105 and the coalescence plates 106 are combined, they are arranged in the upper shell 102, and the feeding hole 1021 is located at the upper end of the spiral flow guide groove of the first spiral flow channel 104.

[0010] Further optimization is made on the basis of the first scheme to obtain the second scheme: the coalescence plate 106 is composed of a plurality of inclined plates to form a corrugated coalescence surface 1062 with a plurality of pits and protrusions, a through hole is arranged at the center position of each pit and protrusion, the through hole is a coalescence hole 1063, and a coalescence plate center hole 1604 is arranged at the center position of the coalescence plate for enabling the overflow pipe 203 to pass through the coalescence plate center hole 1604 and penetrate through all the coalescence plates 106 arranged in the coalescence shell 105.

[0011] Further optimization is made on the second scheme to obtain the third scheme:

[0012] The lower end of the coalescence shell 105 is provided with a reduced diameter section, and the bottom opening of the reduced diameter section is arranged to be only for the overflow pipe 203 to pass through.

[0013] Further optimization is made on the third scheme to obtain the fourth scheme:

[0014] The downhole separation assembly further comprises a fine separation module;

[0015] The fine separation module comprises a lower shell 201, an overflow pipe 203, a second spiral flow channel 204 and an inverted cone 205;

[0016] The top end of the second spiral flow channel 204 is provided with a flow guide frustum, and a spiral flow guide groove is arranged on the outer wall of the second spiral flow channel 204; a long through hole, i.e., an overflow port 2041, is arranged at the center of the second spiral flow channel 204, and the top end of the long through hole is provided with threads for connecting with the overflow pipe 203 through threads;

[0017] The inverted cone 205 is provided with a water phase outlet 2051;

[0018] The upper end of the lower housing 201 is connected with the upper housing 102 by screw thread; the secondary spiral flow channel 204 and the lower end of the inverted cone 205 are connected with the inside of the lower housing 201 by screw thread in turn.

[0019] Further, a frustoconical cavity is arranged between the bottom end of the long through hole and the bottom end of the secondary spiral flow channel 204.

[0020] Further, the inner cavity of the lower housing 201 is arranged as an inverted frustoconical cavity and a straight tube cavity; the secondary spiral flow channel 204 and the inverted cone 205 are respectively located at the top end and the bottom end of the straight tube cavity.

[0021] Further, the peripheral diameter of the secondary spiral flow channel is reduced to one third to one half of the peripheral diameter of the primary spiral flow channel.

[0022] Another aspect of the application is to provide a downhole multi-stage spiral nested oil-water fine separation device, which is unique in that:

[0023] Any one of the downhole separation assemblies in the application scheme 4 and the further optimization scheme; and the lower tubing coupling 202 and the upper tubing coupling 101;

[0024] The upper tubing coupling 101 is connected with the lower spiral flow channel end cover 103 by screw thread; the lower end of the lower housing 201 is connected with the tubing coupling 202 by screw thread.

[0025] Further, the application in the present disclosure extends to a same-well injection-production process string, which is unique in that the aforementioned downhole multi-stage spiral nested oil-water fine separation device is inserted into the process string.

[0026] The above at least one technical scheme adopted by one or more embodiments of the present disclosure can achieve the following beneficial effects:

[0027] Firstly, the present device innovatively designs a connection form of first passing through a spiral flow channel and then a sedimentation and coalescence device to realize further purification and separation of oil phase and water phase medium.

[0028] Secondly, the present device innovatively designs a reduced-diameter structure to connect multi-stage separation devices in series, which greatly improves the separation precision and provides a new type of multi-stage separation structure in series.

[0029] In addition, the present device innovatively designs a sedimentation and coalescence device, which can achieve multi-layer coalescence and gravity enhancement.

[0030] Finally, the device has simple structure, combines cyclone, sedimentation and coalescence technologies, and realizes multi-stage fine separation of oil-water two-phase medium in narrow space, and further improves oil-water separation efficiency.

[0031] In conclusion, the downhole multi-stage spiral nested oil-water fine separation device has the advantages of simple structure, compact arrangement, etc., and the multi-stage separation device connected in series in the reduced diameter structure greatly improves the separation precision of downhole oil-water two-phase medium, reduces the lifting cost of water phase, relieves the working pressure and maintenance cycle of the lifting pump, and improves the economic benefit.

[0032] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, but not limiting the present disclosure.

[0033] Other features and aspects of the present disclosure will become apparent from the following detailed description of example embodiments, taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0034] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments consistent with the present disclosure and serve to explain the technical solutions of the present disclosure together with the specification.

[0035] Figure 1 (a) is a whole appearance view of a downhole multi-stage spiral sedimentation nested oil-water fine separation device.

[0036] Figure 1 (b) is a sectional view of a downhole multi-stage spiral sedimentation nested oil-water fine separation device.

[0037] Figure 2 It is an explosion view of a downhole multi-stage spiral sedimentation nested oil-water fine separation device.

[0038] Figure 3 (a) is a spiral sedimentation module appearance view.

[0039] Figure 3 (b) is a spiral sedimentation module sectional view.

[0040] Figure 4 It is an explosion view of a spiral sedimentation module.

[0041] Figure 5 (a) is a coalescence plate top view structure.

[0042] Figure 5 (b) is a coalescence plate bottom view structure.

[0043] Figure 6 (a) is a fine separation module appearance view.

[0044] Figure 6 (b) is a cross-sectional view of the fine separation module.

[0045] Figure 7 This is an exploded view of the finely separated modules.

[0046] Figure 8 This is a diagram illustrating the reduced diameter structure.

[0047] In the diagram, 101-upper oil pipe coupling, 102-upper outer shell, 1021-feed hole, 103-spiral flow channel end cap, 1031-oil phase outlet, 104-first-stage spiral flow channel, 1041-liquid inlet, 1042-first-stage spiral flow channel inner cavity, 105-coalescing outer shell, 106-coalescing plate, 1061-connecting outer shell, 1062-coalescing surface, 1063-coalescing hole, 1064-coalescing plate center hole, 201-lower outer shell, 202-lower oil pipe coupling, 203-overflow pipe, 204-secondary spiral flow channel, 2041-overflow port, 205-inverted cone, 2051-aqueous phase outlet. Detailed Implementation

[0048] Various exemplary embodiments, features, and aspects of this disclosure will now be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings denote elements that have the same or similar functions. Although various aspects of the embodiments are shown in the drawings, they are not necessarily drawn to scale unless specifically indicated otherwise.

[0049] The term “exemplary” as used herein means “serving as an example, embodiment, or illustration.” Any embodiment illustrated herein as “exemplary” is not necessarily to be construed as superior to or better than other embodiments.

[0050] Furthermore, to better illustrate this disclosure, numerous specific details are set forth in the following detailed description. Those skilled in the art will understand that this disclosure can be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of this disclosure.

[0051] This type of downhole multi-stage spiral nested oil-water fine separation device includes a spiral settling module and a fine separation module, wherein:

[0052] The spiral settling module includes an upper oil pipe coupling 101, an upper outer shell 102, a spiral flow channel end cap 103, a primary spiral flow channel 104, a coalescing outer shell 105, and a coalescing plate 106.

[0053] The oil pipe coupling 101 is connected with the lower spiral flow channel end cover 103 through thread connection; the lower end of the spiral flow channel end cover 103 is connected with the first-stage spiral flow channel 104 and the upper shell 102 through thread connection from inside and outside respectively; the surface of the upper shell 102 is provided with a feeding hole 1021, and the lower end is connected with the lower shell 201 through thread connection; the lower end of the first-stage spiral flow channel 104 is provided with a liquid inlet hole 1041, and the lower end is connected with the coalescence shell 105 through thread connection; the coalescence plate 106 is connected with the coalescence shell 105 through thread connection and is arranged inside the coalescence shell 105.

[0054] The coalescence plate 106 is composed of a plurality of inclined plates, forms a corrugated coalescence surface 1062 with a plurality of pits and protrusions, and is provided with a through hole, i.e. a coalescence hole 1063, at the center position of each pit and protrusion; the center position of the entire coalescence plate is provided with a coalescence plate center hole 1604, and the overflow pipe 203 penetrates through each coalescence plate 106 through the coalescence plate center hole 1604; the thread on the connecting shell 1061 is used to connect with the internal thread of the coalescence shell 105 and each coalescence plate 106.

[0055] The fine separation module comprises a lower shell 201, a lower oil pipe coupling 202, an overflow pipe 203, a second-stage spiral flow channel 204 and an inverted cone 205.

[0056] The lower shell 201 is connected with the upper shell 102 and the lower oil pipe coupling 202 through thread connection from top to bottom; the second-stage spiral flow channel 204 and the inverted cone 205 are sequentially connected with the inside of the lower shell 201 through external thread connection from bottom to top, and the inverted cone 205 is provided with a water phase outlet 2051 on the upper end; the upper end of the second-stage spiral flow channel 204 is connected with the overflow pipe 203 through thread connection.

[0057] The spiral settling module and the fine separation module are vertically placed in the wellbore in sequence from top to bottom. The inner diameter of the structure is reduced from the spiral settling module to the fine separation module, and the outer diameter of the second-stage spiral flow channel is reduced to one third to one half of the outer diameter of the first-stage spiral flow channel. The mixed liquid separated by the spiral settling module enters the fine separation module with reduced diameter, so that the separation effect is further improved.

[0058] The overall appearance and sectional view of the downhole multi-stage spiral settling nested oil-water fine separation device are as shown in Figure 1 The exploded view is as shown in Figure 2 The device mainly comprises a spiral settling module and a fine separation module.

[0059] The device is vertically placed in the well, and when working, the oil-water mixture enters the device from the feed hole 1021, and after passing through the first spiral flow channel 104, the oil phase is close to the inner wall of the first spiral flow channel 104, and the water phase is in the periphery. The oil phase and part of the water phase medium enter the inner cavity 1042 of the first spiral flow channel from the liquid inlet hole 1041 to carry out sedimentation separation. The water phase generated by the external cyclone separation and the liquid phase after the oil-water in the inner part are settled after passing through the coalescence plate 106 are converged and then enter the second spiral flow channel 204. The water phase after the second separation is discharged into the lower oil pipe coupling 202 through the water phase outlet 2051. The oil phase medium after the second separation is combined with the oil phase separated by sedimentation after passing through the overflow port 2041 and the overflow pipe 203, and then enters the upper oil pipe coupling 101 from the oil phase outlet 1031, and is finally lifted to the ground.

[0060] The appearance and sectional view of the spiral sedimentation module are shown in Figure 3 The upper and lower ends of the spiral flow channel end cover 103 are respectively screwed with the upper oil pipe coupling 101 and the upper shell 102. The first spiral flow channel 104 is arranged in the upper shell 102. The oil-water mixture enters the spiral flow channel 104 from the feed hole 1021. After acceleration, a cyclone field is formed. When the oil-water mixture passes through the spiral flow channel 104, the oil phase of the light phase is close to the center under the action of the cyclone field, and the heavy phase of the water phase is located in the peripheral area. The central oil phase can enter the gravity separation area above the first spiral flow channel inner cavity 1042 through the upper liquid inlet hole 1041, and part of the water phase enters the gravity separation area below through the lower liquid inlet hole, so as to achieve the effect of strengthening gravity sedimentation. The coalescence plate 106 can promote the small oil droplets that cannot be completely separated by sedimentation to gather into large oil droplets, thereby further strengthening the sedimentation effect. The liquid phase containing a small amount of oil phase after internal sedimentation separation is combined with the water phase after external cyclone separation to enter the fine separation module 2.

[0061] The explosion view of the spiral sedimentation module is shown in Figure 4 The spiral sedimentation module mainly comprises the upper oil pipe coupling 101, the upper shell 102, the spiral flow channel end cover 103, the first spiral flow channel 104, the coalescence shell 105, and the coalescence plate 106.

[0062] The appearance of the coalescence plate is shown in Figure 5 Fig. a and Fig. b are the appearance views of the upper and lower perspectives, respectively. The lower end of the coalescence plate 106 is connected with the coalescence shell 105 through the threads of the connecting shell 1061, and is arranged in the coalescence shell 105. The overflow pipe 203 penetrates through each coalescence plate 106 through the coalescence plate center hole 1604. Each coalescence plate 106 is also connected with each other through the connecting shell 1061. The small oil droplets after separation adhere to the coalescence surface 1062. Under the pushing action of the fluid, the small oil droplets are gathered into large oil droplets at each coalescence hole 1063, which is convenient for separation and lifting for further processing.

[0063] The appearance and sectional view of the fine separation module are shown inFigure 6 As shown in the figure, the lower housing 201 and the lower tubing coupling 202 are connected together by threads; the secondary spiral flow channel 204 and the inverted cone 205 are connected to the inside of the lower housing 201 by external threads in turn, and the inverted cone 205 is provided with a water phase outlet 2051. The upper end of the secondary spiral flow channel 204 is connected with the overflow pipe 203 by threads. The liquid phase containing a small amount of oil separated by the spiral settling module 1 is subjected to a secondary fine separation in the secondary spiral flow channel 204 to strengthen the rotational flow field intensity, and then in the lower rotational flow separation area. The oil phase medium under the action of the rotational flow separation is gathered with the oil phase separated by the overflow pipe 203 through the overflow port 2041 and the overflow pipe 203, and then enters the upper tubing coupling 101 together from the oil phase outlet 1031, and is finally lifted to the ground. The water phase after the secondary fine separation is discharged into the lower tubing coupling 202 through the water phase outlet 2051 of the inverted cone 205.

[0064] The exploded view of the fine separation module is shown in Figure 7 The main components of the fine separation module include the lower housing 201, the lower tubing coupling 202, the overflow pipe 203, the secondary spiral flow channel 204, and the inverted cone 205. The reduced diameter structure is shown in Figure 8 The lower end of the upper housing 102 is connected with the upper end of the lower housing 201 by threads, and the inner diameter of the lower housing 201 is one third to one half of the inner diameter of the upper housing 102. The mixed liquid separated by the spiral settling module enters the fine separation module 2 after the reduction in diameter to perform fine separation, and the separation efficiency is enhanced.

[0065] The device has a compact design structure and reliable and stable operation. The oil-water mixture is first subjected to separation of the oil phase and part of the water phase medium by the spiral settling module, and then subjected to settling separation in the primary spiral flow channel. The oil-water mixture is subjected to enhanced settling separation of the oil phase and the water phase under the action of the rotational flow field and the coalescing device. The reduced diameter structure is used for multi-stage separation device connection, which greatly improves the separation precision. The present application combines the rotational flow, settling, and coalescing technologies to realize multi-stage fine separation of the oil-water two-phase in a small space, has high working efficiency and good separation effect, is conducive to the sustainable development of oil fields, and has high practicality.

[0066] The above-described embodiments are exemplary and are not exhaustive, and are not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical applications, or improvements to the technology in the market, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A downhole separation assembly comprising a spiral settling module, characterized in that: the spiral settling module comprises an upper housing (102), a spiral flow channel end cover (103), a primary spiral flow channel (104), a coalescing housing (105), and coalescing plates (106); the lower end of the spiral flow channel end cover (103) is connected with the primary spiral flow channel (104) by screw threads; the surface of the upper housing (102) is provided with a feed hole (1021), and the lower end of the upper housing (102) is provided with screw threads for connecting with the outer screw threads of a lower housing (201); a straight pipe section inside the primary spiral flow channel (104) is provided with a primary spiral flow channel inner cavity (1042), and a spiral flow guide groove is arranged on the outer wall corresponding to the straight pipe section; a plurality of liquid inlet holes (1041) are arranged on the reduced diameter section of the primary spiral flow channel (104), and the liquid inlet holes are connected with the primary spiral flow channel inner cavity; the reduced diameter section of the primary spiral flow channel (104) is connected with the coalescing housing (105) by screw threads; a plurality of coalescing plates (106) are connected with the coalescing housing (105) by screw threads and are stacked and arranged inside the coalescing housing (105); after the spiral flow channel end cover (103), the primary spiral flow channel (104), the coalescing housing (105), and the coalescing plates (106) are combined, they are arranged in the upper housing (102), and the feed hole (1021) is located at the upper end of the spiral flow guide groove of the primary spiral flow channel (104).

2. The downhole separation assembly according to claim 1, characterized in that: the coalescing plates (106) are composed of a plurality of inclined plates, forming a corrugated coalescing surface (1062) with a plurality of pits and protrusions, and a through hole is arranged at the center of each pit and protrusion, which is a coalescing hole (1063); a coalescing plate center hole (1604) is arranged at the center of the coalescing plate, for allowing an overflow pipe (203) to pass through the coalescing plate center hole (1604) and penetrate through all the coalescing plates (106) arranged in the coalescing housing (105); 3. A downhole separation assembly according to claim 2, characterised in that: a reduced diameter section is arranged at the lower end of the coalescing housing (105), and the bottom opening of the reduced diameter section is arranged to allow only the overflow pipe (203) to pass through.

4. The downhole separation assembly according to claim 3, characterized in that: the downhole separation assembly further comprises a fine separation module; the fine separation module comprises a lower housing (201), an overflow pipe (203), a secondary spiral flow channel (204), and an inverted cone (205); the top end of the secondary spiral flow channel (204) is provided with a flow guide cone, a spiral flow guide groove is arranged on the outer wall of the secondary spiral flow channel (204); a long through hole is arranged at the center of the secondary spiral flow channel (204), and the top end of the long through hole is provided with screw threads for connecting with the overflow pipe (203) by screw threads; a water phase outlet (2051) is arranged on the inverted cone (205); the upper end of the lower housing (201) is connected with the upper housing (102) by screw threads; the secondary spiral flow channel (204) and the lower end of the inverted cone (205) are sequentially connected with the inside of the lower housing (201) by outer screw threads.

5. A downhole separation assembly according to claim 4, characterised in that: a cone-shaped cavity is arranged between the bottom end of the long through hole and the bottom end of the secondary spiral flow channel (204).

6. A downhole separation assembly according to claim 5, characterised in that: The inner cavity of the lower housing (201) is designed as an inverted frustum-shaped cavity and a straight tube cavity; the secondary spiral flow channel (204) and the inverted cone (205) are respectively located at the top end and the bottom end of the straight tube cavity.

7. A downhole separation assembly according to claim 6, characterised in that: The outer diameter of the secondary spiral flow channel is reduced to one third to one half of the outer diameter of the primary spiral flow channel.

8. A downhole multi-stage spiral nested oil-water fine separation device, characterized in that: any one of the downhole separation assemblies in claims 4 to 7 is applied; and a lower tubing coupling (202) and an upper tubing coupling (101); the upper tubing coupling (101) is connected with the lower spiral flow channel end cover (103) through threads; and the lower end of the lower housing (201) is connected with the lower tubing coupling (202) through threads.

9. A downhole process string characterized by The downhole multi-stage spiral nested oil-water fine separation device in claim 8 is connected into the process column. The outer diameter of the secondary spiral flow channel is reduced to one third to one half of the outer diameter of the primary spiral flow channel.

8. A downhole multi-stage spiral nested oil-water fine separation device, characterized in that: any one of the downhole separation assemblies in claims 4 to 7 is applied; and a lower tubing coupling (202) and an upper tubing coupling (101); the upper tubing coupling (101) is connected with the lower spiral flow channel end cover (103) through threads; and the lower end of the lower housing (201) is connected with the lower tubing coupling (202) through threads. The downhole multi-stage spiral nested oil-water fine separation device in claim 8 is connected into the process column.

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