Shale oil horizontal well flowback fluid multi-stage sand setting device and method

Abstract

The invention discloses a shale oil horizontal well flow-back fluid multi-stage sand setting device and method, and belongs to the technical field of petroleum fracturing, the shale oil horizontal well flow-back fluid multi-stage sand setting device comprises a sand setting tank, a first-stage settling area, a second-stage settling area and a third-stage settling area, the first-stage settling area, the second-stage settling area and the third-stage settling area are sequentially communicated from left to right in the sand setting tank, and the first-stage settling area comprises a flow-back fluid inflow pipe and a first-stage filter plate; the upper end of the flow-back fluid inflow pipe is a feed port, the lower end of the flow-back fluid inflow pipe is communicated with the first-stage sedimentation area, and the first-stage filter plate is arranged at the upper end of the first-stage sedimentation area; a filtering inclined plate assembly is arranged in the second-stage sedimentation area, the lower end of the filtering inclined plate assembly is rotationally arranged on a placement frame, and the filtering inclined plate assembly is driven by a driving assembly to rotate, so that the included angle between the filtering inclined plate assembly and the horizontal line is adjusted within 60-95 degrees; a second filter plate is arranged in the tertiary settling stage descending area, and a discharge hole is formed in the upper end of the tertiary settling stage descending area.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil fracturing, and particularly relates to a multi-stage sand settling device and method for the flowback fluid of shale oil horizontal wells. Background Art

[0002] In recent years, with the continuous exploration and development of shale oil, large-scale fracturing is one of the most important methods for efficient development of shale oil. At the same time, a large amount of fracturing fluid will enter the reservoir during the fracturing process. Therefore, flowback operations are carried out after fracturing. Each well produces approximately 1000 m3 of flowback fluid after fracturing. These flowback fluids contain a large amount of biological glue, sand, oil and other chemical additives, which are characterized by high pollutant concentration and dispersed pollution sources. If the flowback fluid is not properly treated and discharged, it will cause serious pollution to the surrounding environment and surface water systems, especially increasing the water use pressure in the water-scarce northwest region. With the implementation of the new environmental protection law, the intensity of environmental protection in the process of oil and gas field development has been greatly improved. How to treat a large amount of flowback fluid has become the key to the green development of oil and gas fields. There are three main goals for the treatment of oil well flowback fluid in China: The first is to reinject after pretreatment, but the water quality must meet the national standard requirements. This method can not only supplement formation energy but also save water resources. The second is recycling and reuse. After the flowback fluid is treated, its pH value, bacterial content, suspended solid content, ion content, etc. must meet the requirements for reuse in preparing fluids and cause no harm to the reservoir. The third is to transport it to a designated waste treatment company for harmless treatment. The latter two schemes require on-site storage, so multiple large tanks are equipped on-site to store the flowback fluid.

[0003] At present, the treatment method for the flowback fluid of oil well fracturing fluid is to flow it back into a simple sand settling tank, let it naturally settle in the sand settling tank, and use vertical baffles with different pore sizes 2 - 3 times for 2 - 3 times of settling. After a long time of use, the pores of the baffles will be blocked. When the flow rate is large, the liquid will flow over the baffles and enter the liquid storage tank. In this case, a large amount of flowback sand will also enter the subsequent liquid storage tank, resulting in the situation that there is support in the liquid storage tank. Later, it is necessary to treat the sand in the liquid storage tank, and personnel need to enter the confined space of the liquid storage tank for sand cleaning operations, increasing the labor intensity of the operators and increasing the safety risks. The automatic multi-stage sand settling device for the flowback fluid of shale oil horizontal wells is a set of multi-stage sand removal devices developed based on the above situation. This device is applicable to the range of oil wells. Using this device and method can efficiently separate the sand in the flowback fluid, and has the characteristics of safe, simple operation and high automation degree.

[0004] The present invention conducts scientific and reasonable analysis on the above situation and independently develops an automatic multi-stage sand settling device and method for the flowback fluid of shale oil horizontal wells. Considering the real well site situation of the blowout pressure of the oil well in the present invention, in order to efficiently treat the sand in the flowback fluid, an automatic multi-stage sand settling device for the flowback fluid of shale oil horizontal wells is developed for the treatment of the flowback fluid, etc. Summary of the Invention

[0005] In view of the above problems, the object of the present invention is to provide a multi-stage sand settling device and method for the flow-back fluid of a shale oil horizontal well.

[0006] The object of the present invention is achieved by the following technical solutions: A multi-stage sand settling device for the flow-back fluid of a shale oil horizontal well includes a sand settling tank, which is sequentially connected with a first-stage settling area, a second-stage settling area, and a third-stage settling area from left to right. The first-stage settling area includes a flow-back fluid inlet pipe and a first filter plate. The upper end of the flow-back fluid inlet pipe is a feed port, and the lower end of the flow-back fluid inlet pipe is connected to the first-stage settling area. The first filter plate is arranged at the upper end of the first-stage settling area. A filtering inclined plate assembly is arranged in the second-stage settling area. The lower end of the filtering inclined plate assembly is rotatably arranged on a placement rack, and the filtering inclined plate assembly is driven by a driving assembly to rotate, so that the included angle between the filtering inclined plate assembly and the horizontal line is adjusted within 60° - 95°. A second filter plate is arranged in the third-stage settling area, and a discharge port is arranged at the upper end of the third-stage settling area.

[0007] Preferably, the filtering inclined plate assembly includes a plurality of filtering inclined plates, and the upper ends of the plurality of filtering inclined plates are connected by a connecting rod.

[0008] Preferably, the lower end of the filtering inclined plate is rotatably arranged on the placement rack through a mounting seat.

[0009] Preferably, the driving assembly includes a driving impeller and an eccentric wheel. The driving impeller is arranged in the flow-back fluid inlet pipe. The driving impeller drives the eccentric wheel to rotate through a transmission belt. A driving block is arranged on the eccentric wheel, the driving block is connected to a pull rope, and the other end of the pull rope is connected to the connecting rod.

[0010] Preferably, a blocking isolation cloth is arranged at the upper end of the second-stage settling area.

[0011] Preferably, the horizontal height of the feed port is at least 2 m higher than the horizontal height of the first filter plate.

[0012] Preferably, the aperture of the first filter plate is 5 mm; the aperture of the second filter plate is 3 mm.

[0013] Preferably, the first filter plate is placed on a first mounting block in the first-stage settling area; the second filter plate is placed on a second mounting block in the third-stage settling area.

[0014] Preferably, the volume of the sand settling tank is 50 m³.

[0015] A multi-stage sand settling method for the flow-back fluid of a shale oil horizontal well includes the following steps: Step 1: The backflow liquid enters the backflow liquid discharge pipe through the feed port and undergoes primary sedimentation in the primary sedimentation area. After the primary sedimentation area is filled with the backflow liquid, the backflow liquid is filtered through the primary filter plate and then discharged into the secondary sedimentation area. Step 2: After the backflow liquid enters the secondary sedimentation area, it climbs upward through the gaps between the filter inclined plates. The impurities stay on the filter inclined plates and are then discharged into the tertiary sedimentation area from the upper end of the secondary sedimentation area. The driving assembly drives the filter inclined plate assembly to rotate, adjusting the angle between the filter inclined plate assembly and the horizontal line to be between 60° and 95°, making it easier for the impurities that are not easily slipped to slide off the filter inclined plates and fall into the lower end of the secondary sedimentation area. Step 3: After the backflow liquid enters the tertiary sedimentation area, it undergoes tertiary sedimentation in the tertiary sedimentation area. The backflow liquid is filtered through the secondary filter plate and finally discharged through the discharge port.

[0016] The beneficial effects of this technical solution are as follows: 1. A multi-stage sand settling device for shale oil horizontal well backflow liquid provided by the present invention designs an automatic multi-stage sand settling device for shale oil horizontal well backflow liquid. The device is designed with 3 stages of sedimentation to settle sands and solids of different particle sizes.

[0017] 2. A multi-stage sand settling device for shale oil horizontal well backflow liquid provided by the present invention can efficiently settle and separate sands and solids of various particle sizes according to the size of the backflow liquid, improving work efficiency and reducing operation risks.

[0018] 3. A multi-stage sand settling device for shale oil horizontal well backflow liquid provided by the present invention is safe and simple to operate: it can be operated by 1 person; it has a high degree of automation, makes full use of the wellhead pressure, and avoids the restriction of equipment operation by external factors such as electricity. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a connection schematic diagram of the present invention; Figure 2 It is a connection schematic diagram of the filter inclined plate assembly in the present invention; Figure 3 It is a connection schematic diagram of the driving assembly in the present invention; Wherein: 100, sand settling tank; 110, primary sedimentation area; 111, backflow liquid inflow pipe; 112, primary filter plate; 113, feed port; 114, first mounting block; 120, secondary sedimentation area; 121, blocking isolation cloth; 130, tertiary sedimentation area; 131, secondary filter plate; 132, discharge port; 133, second mounting block; 140, filter inclined plate assembly; 141, filter inclined plate; 142, connecting rod; 143, mounting seat; 144, placement rack; 150, driving assembly; 151, driving impeller; 152, eccentric wheel; 153, transmission belt; 154, driving block; 155, pulling rope. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be further described in detail below in conjunction with embodiments, but the implementation manners of the present invention are not limited thereto.

[0021] Embodiment 1 As Figure 1 shown, this embodiment provides a multi-stage sand settling device for shale oil horizontal well flowback fluid, including a sand settling tank 100. Inside the sand settling tank 100, a first-stage settling area 110, a second-stage settling area 120, and a third-stage settling area 130 are connected in sequence from left to right. The first-stage settling area 110 includes a flowback fluid inlet pipe 111 and a first-stage filter plate 112. The upper end of the flowback fluid inlet pipe 111 is a feed port 113, and the lower end of the flowback fluid inlet pipe 111 is connected to the first-stage settling area 110. The first-stage filter plate is arranged at the upper end of the first-stage settling area 110. A filtering inclined plate assembly 140 is arranged in the second-stage settling area 120. The lower end of the filtering inclined plate assembly 140 is rotatably arranged on a placement rack 144. The filtering inclined plate assembly 140 is driven by a driving assembly 150 to rotate, so that the angle between the filtering inclined plate assembly 140 and the horizontal line is periodically adjusted between 60° and 95° according to the size of the flowback fluid. A second filter plate is arranged in the third-stage settling area, and a discharge port 132 is arranged at the upper end of the third-stage settling area.

[0022] Embodiment 2 As Figure 2 shown, the difference between this embodiment and Embodiment 1 is that: among them, the filtering inclined plate assembly 140 includes a plurality of filtering inclined plates 141, and the upper ends of the plurality of filtering inclined plates 141 are connected by a connecting rod 142.

[0023] Among them, the lower end of the filtering inclined plate 141 is rotatably arranged on the placement rack 144 through a mounting seat 143.

[0024] As Figure 3As shown in the figure, the drive assembly 150 includes a drive impeller 151 and an eccentric wheel. The drive impeller 151 is arranged in the return fluid inlet pipe. The drive impeller 151 drives the eccentric wheel to rotate through a transmission belt 153. A driving block 154 is arranged on the eccentric wheel. The driving block 154 is connected to a pull rope 155, and the other end of the pull rope 155 is connected to a connecting rod 142. The return fluid with pressure in the return fluid inflow pipe 111 drives the drive impeller 151 to rotate. A first runner coaxially arranged with the drive impeller 151 and a second runner coaxially arranged with the eccentric wheel are connected through a transmission belt 153. The drive impeller 151 drives the eccentric wheel to rotate. The driving block 154 on the eccentric wheel rotates with the eccentric wheel, causing the pull rope 155 to be pulled, so that the angle between the filter inclined plate 141 and the horizontal line is adjusted between 60° and 95°. When the angle between the filter inclined plate 141 and the horizontal line is 95°, impurities (sand or solids) that are not easily slipped off on the filter inclined plate 141 slide into the lower end of the secondary sedimentation area 120.

[0025] Wherein, a blocking isolation cloth 121 is arranged at the upper end of the secondary sedimentation area 120. The arrangement of the blocking isolation cloth 121 prevents the return fluid from entering the tertiary sedimentation area 130 without passing through the filter inclined plate 141, ensuring the filtering effect.

[0026] Wherein, the horizontal height of the feed inlet 113 is at least 2 m higher than the horizontal height of the first filter plate. The opening at the bottom of the primary sedimentation area 110 becomes larger and the flow rate becomes slower to form a natural sedimentation area. Then the return fluid slowly rises. Large sand and large particle substances cannot pass through the primary filter plate 112 with a pore diameter of 5 mm and are isolated and slowly deposited. The flow rate of the return fluid passing through the primary filter plate 112 can be increased, and the return fluid continues to enter the filtering inclined plate 141 section in the secondary sedimentation area 120.

[0027] Wherein, the pore diameter of the primary filter plate 112 is 5 mm; the pore diameter of the secondary filter plate 131 is 3 mm.

[0028] Wherein, the primary filter plate 112 is placed on the first mounting block 114 in the primary sedimentation area 110; the secondary filter plate 131 is placed on the second mounting block 133 in the tertiary sedimentation area 130.

[0029] Wherein, the volume of the sand settling tank 100 is 50 m³.

[0030] Example 3 The difference between this example and Example 2 is that there are 20 filter inclined plates 141 in total, and the distance between each two filter inclined plates 141 is 50 mm.

[0031] A multi-stage sand settling method for shale oil horizontal well return fluid, using a multi-stage sand settling device for shale oil horizontal well return fluid, which includes the following steps: Step 1: The backflow fluid enters the backflow fluid discharge pipe through the feed port 113, and the backflow fluid enters the first-stage sedimentation area 110 for first-stage sedimentation. After the first-stage sedimentation area 110 is filled with the backflow fluid, the backflow fluid is filtered through the first-stage filter plate 112 and then discharged into the second-stage sedimentation area 120; Step 2: After the backflow fluid enters the second-stage sedimentation area 120, the backflow fluid climbs upward through the gaps between the filter inclined plates 141, and the impurities stay on the filter inclined plates 141, and then are discharged into the third-stage sedimentation area 130 from the upper end of the second-stage sedimentation area 120; the driving assembly 150 drives the filter inclined plate assembly 140 to rotate, so that the angle between the filter inclined plate assembly 140 and the horizontal line is periodically adjusted between 60° - 95° according to the size of the backflow fluid, making it easier for the impurities that are not easy to slide off to slide into the lower end of the second-stage sedimentation area 120 from the filter inclined plates 141; Step 3: After the backflow fluid enters the third-stage sedimentation area 130, the backflow fluid enters the third-stage sedimentation area 130 for third-stage sedimentation. After being filtered through the second-stage filter plate 131, the backflow fluid is finally discharged through the discharge port 132.

[0032] The beneficial effects of this technical solution are as follows: First, a multi-stage sand settling device for shale oil horizontal well backflow fluid provided by the present invention designs an automatic multi-stage sand settling device for shale oil horizontal well backflow fluid. The device designs 3 stages of sedimentation to settle sands and solids with different particle sizes.

[0033] Second, a multi-stage sand settling device for shale oil horizontal well backflow fluid provided by the present invention can efficiently settle and separate sands and solids with various particle sizes according to the size of the backflow fluid, improve work efficiency, and reduce operation risks.

[0034] Third, a multi-stage sand settling device for shale oil horizontal well backflow fluid provided by the present invention is safe and simple to operate: it can be operated by 1 person; it has a high degree of automation, makes full use of the wellhead pressure, and avoids the restriction of equipment operation by external factors such as electricity.

[0035] Finally, it should be noted that: the above embodiments are only used to illustrate, rather than limit the technical solution of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: the present invention can still be modified or equivalently replaced, and any modification or partial replacement without departing from the spirit and scope of the present invention shall be covered by the scope of the claims of the present invention.

Claims

1. A multi-stage sand settling device for the flowback fluid of a shale oil horizontal well, characterized in that, it includes a sand settling tank (100), and a first-stage settling area (110), a second-stage settling area (120) and a third-stage settling area (130) which are connected in sequence from left to right in the sand settling tank (100). The first-stage settling area (110) includes a flowback fluid inlet pipe (111) and a first filter plate (112). The upper end of the flowback fluid inlet pipe (111) is a feed inlet (113), the lower end of the flowback fluid inlet pipe (111) is connected to the first-stage settling area (110), and the first filter plate is arranged at the upper end of the first-stage settling area (110); a filter inclined plate assembly (140) is arranged in the second-stage settling area (120), the lower end of the filter inclined plate assembly (140) is rotatably arranged on a placement rack (144), and the filter inclined plate assembly (140) is driven by a driving assembly (150) to rotate, so that the included angle between the filter inclined plate assembly (140) and the horizontal line is adjusted within 60° - 95°; a second filter plate is arranged in the third-stage settling area (130), and a discharge port (132) is arranged at the upper end of the third-stage settling area (130).

2. A multi-stage sand settling device for the flowback fluid of a shale oil horizontal well according to claim 1, characterized in that: the filter inclined plate assembly (140) includes a plurality of filter inclined plates (141), and the upper ends of the plurality of filter inclined plates (141) are connected by a connecting rod (142).

3. A multi-stage sand settling device for the flowback fluid of a shale oil horizontal well according to claim 2, characterized in that: the lower end of the filter inclined plate (141) is rotatably arranged on the placement rack (144) through a mounting seat (143).

4. A multi-stage sand settling device for the flowback fluid of a shale oil horizontal well according to claim 3, characterized in that: the driving assembly (150) includes a driving impeller (151) and an eccentric wheel (152). The driving impeller (151) is arranged in the flowback fluid inlet pipe. The driving impeller (151) drives the eccentric wheel (152) to rotate through a transmission belt (153). A driving block (154) is arranged on the eccentric wheel (152), the driving block (154) is connected to a pull rope (155), and the other end of the pull rope (155) is connected to the connecting rod (142).

5. A multi-stage sand settling device for the flowback fluid of a shale oil horizontal well according to claim 1, characterized in that: a blocking isolation cloth (121) is arranged at the upper end of the second-stage settling area (120).

6. A multi-stage sand settling device for the flowback fluid of a shale oil horizontal well according to claim 1, characterized in that: the horizontal height of the feed inlet (113) is at least 2 m higher than the horizontal height of the first filter plate.

7. A multi-stage sand settling device for the flowback fluid of a shale oil horizontal well according to claim 6, characterized in that: the aperture of the first filter plate (112) is 5 mm; the aperture of the second filter plate (131) is 3 mm.

8. A multi-stage sand settling device for the flowback fluid of a shale oil horizontal well according to claim 1, characterized in that: The first-stage filter plate (112) is placed on the first mounting block (114) in the first sedimentation area (110); the second-stage filter plate (131) is placed on the second mounting block (133) in the third sedimentation area (130).

9. A multi-stage sand settling device for shale oil horizontal well flowback fluid according to claim 1, characterized in that: The volume of the sand settling tank (100) is 50 m³.

10. A multi-stage sand settling method for shale oil horizontal well flowback fluid, characterized in that, it includes the following steps: Step 1: The flowback fluid enters the flowback fluid discharge pipe through the feed port (113), and the flowback fluid enters the first sedimentation area (110) for primary sedimentation. After the first sedimentation area (110) is filled with the flowback fluid, the flowback fluid is filtered through the first-stage filter plate (112) and then discharged into the second sedimentation area (120); Step 2: After the flowback fluid enters the second sedimentation area (120), the flowback fluid climbs upward through the gaps between the filter inclined plates (141), and the impurities stay on the filter inclined plates (141), and then are discharged into the third sedimentation area (130) from the upper end of the second sedimentation area (120); the driving assembly (150) drives the filter inclined plate assembly (140) to rotate, so that the angle between the filter inclined plate assembly (140) and the horizontal line is adjusted between 60° and 95°, making it easier for the impurities that are not easy to slide off to slide from the filter inclined plates (141) into the lower end of the second sedimentation area (120); Step 3: After the flowback fluid enters the third sedimentation area (130), the flowback fluid enters the third sedimentation area (130) for tertiary sedimentation. After being filtered by the second-stage filter plate (131), the flowback fluid is finally discharged through the discharge port (132).

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