Geothermal tail water recharging device for sandstone thermal reservoir
By setting up a multi-layered filtration structure and stepped connectors on the filter pipe, efficient tailwater reinjection in dense sandstone was achieved, solving the problems of clogging and adaptability, and improving reinjection efficiency and cleanliness.
Patent Information
- Application Number
- CN202511668563.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-14
- Publication Date
- 2026-02-06
AI Technical Summary
Traditional filter pipes are easily clogged in dense sandstone, resulting in a reduction in tailwater reinjection volume. Furthermore, the filter structure has low adaptability and cannot adapt to reinjection wells of different diameters.
It adopts a multi-layer filtration structure, including a filled screen tube assembly and a wound wire screen tube assembly. Through graded filtration of different filter particle materials, combined with stepped connectors, it can adapt to different formation permeability, reduce the risk of clogging, and improve filtration accuracy and flow rate.
It effectively removes suspended solids and impurities from the tailwater, increases the reinjection volume, ensures tailwater cleanliness, prevents blockage, adapts to reinjection wells of different diameters, and reduces operation and maintenance costs.
Smart Images
Figure CN121474732A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of geothermal tail water reinjection, and particularly relates to a geothermal tail water reinjection device for sandstone thermal reservoir. BACKGROUND
[0002] As a clean and renewable energy, geothermal resources play an important role in the transformation of global energy structure. However, overexploitation or improper maintenance of geothermal resources can lead to resource depletion, and direct discharge of geothermal tail water can pollute the environment. In order to ensure the sustainable development of geothermal resources and avoid environmental pollution, geothermal tail water reinjection technology emerges as the times require. This technology re-injects the used geothermal water back into the thermal reservoir section, not only solving the problem of geothermal wastewater, but also improving or restoring the heat production capacity of the geothermal reservoir, maintaining the fluid pressure of the geothermal reservoir and maintaining the continuous exploitation and recycling of the geothermal field. Since the filter pipe (such as a bridge type or a winding wire type) is easily blocked in dense sandstone with a permeability of <100 mD, changes in temperature, pH value, pressure and flow rate of geothermal fluid can easily cause changes in mineral solubility, leading to scaling and adhesion on the filter pipe, resulting in blockage of the reinjection channel. Therefore, the reinjection device increases the filter structure on the filter pipe to filter the tail water.
[0003] However, the traditional filter structure usually adopts a single-layer filler filter structure, which is easily blocked after long-term use. The tail water may be subjected to resistance of the filter structure during the filtering process, resulting in a decrease in the flow rate and reinjection amount of the tail water. In addition, the downhole operation and maintenance cost is high, and the traditional filter structure has low adaptability and cannot be installed in reinjection wells with different diameters, thereby reducing the reinjection efficiency. SUMMARY
[0004] The present application solves the problem that the traditional filter structure on the filter pipe usually adopts a single-layer filler filter structure, and the tail water is easily subjected to resistance of the filter structure during use, which is easily blocked, resulting in a decrease in the reinjection amount of the tail water, and the filter structure has low adaptability.
[0005] In order to solve the above technical problems, the present application provides a geothermal tail water reinjection device for sandstone thermal reservoir, which comprises a sleeve and a base pipe inserted into the inner cavity of the sleeve, the inner wall of the sleeve is fixedly connected with a plurality of stepped connecting pieces, two filler screen pipe assemblies for preventing scaling are arranged on the base pipe, and a winding screen pipe assembly for draining water is fixedly communicated with the bottom end of the base pipe. The filler screen pipe assembly comprises a perforated pipe fixedly communicated with the base pipe, the surface of the perforated pipe is covered with a filler filter layer, a plurality of first flow guide grooves are formed in the surface of the filler filter layer, and a conical water inlet pipe is fixedly connected with the top end of the filler filter layer. The wire-wound screen assembly comprises a center pipe, a plurality of longitudinal support rods are fixedly connected to the middle part of the center pipe, a wire-wound layer is arranged on the surface of the longitudinal support rods, a spiral flow guide ring is fixedly connected to the surface of the wire-wound layer, and a plurality of annular flow guide plates are arranged on the inner wall of the longitudinal support rods.
[0006] Preferably, the filling filter layer is composed of a plurality of layers of filtering granular materials, and two filling screen assemblies are sequentially arranged from top to bottom, the filling filter layer in the upper filling screen assembly is made of relatively large filtering granular materials, and the filling filter layer in the lower filling screen assembly is made of relatively small filtering granular materials.
[0007] Preferably, an outer protective sleeve is arranged on the surface of the filling filter layer, the first flow guide groove is located between the filling filter layer and the outer protective sleeve, and a plurality of through holes are formed in the surface of the perforated pipe and the outer protective sleeve.
[0008] Preferably, the wire-wound layers have the same winding spacing, a filtering gap is formed between two adjacent turns of the wire-wound layers, and the cross section of the filtering gap is in the shape of a trapezoid.
[0009] Preferably, the wire-wound layers are made of stainless steel wires and have the cross section in the shape of a trapezoid.
[0010] Preferably, the cross section of the annular flow guide plate is in the shape of a triangle, the cross section gradually decreases from the inner wall to the wire-wound layer, the plurality of annular flow guide plates are arranged at equal distances, and the positions of the annular flow guide plates correspond to the positions of the filtering gaps.
[0011] Preferably, the spiral flow guide rings are located between the wire-wound sleeve pipes, and a second flow guide groove is formed between two adjacent turns of the spiral flow guide rings.
[0012] Preferably, the bottom end of the perforated pipe is fixedly connected with a first stepped connecting end, the bottom end of the center pipe is fixedly connected with a second stepped connecting end, and the first and second stepped connecting ends are matched with the position and shape of the stepped connecting piece.
[0013] Preferably, the intersection of the longitudinal support rods and the wire-wound layer is connected by welding.
[0014] Technical effects and advantages of the present application: The application filters tail water by two filling screen pipe assemblies and wire-wound screen pipe assembly, and sequentially sets the filling screen pipe assembly with larger filtering particle material, the filling screen pipe assembly with small particle material and the wire-wound screen pipe assembly from top to bottom, tail water enters through the base pipe, sequentially passes through the two filling screen pipe assemblies and the wire-wound screen pipe assembly, the upper filling screen pipe assembly filters larger particles in tail water, the lower filling screen pipe assembly filters small particles in tail water, effectively removes suspended solids and coarse particles in tail water through the effect of physical interception, adopts different sizes of particles to form graded filtration, gradually intercepts impurities of different sizes, reduces the risk of single layer filling blockage, effectively improves the filtering precision of the structure, and ensures that tail water reaches higher cleanliness before entering the wire-wound screen pipe.
[0015] The application completes the last filtration by the wire-wound screen pipe assembly and realizes the recharge operation, tail water filtered by the two filling screen pipe assemblies enters the inner cavity of the wire-wound screen pipe assembly, and the tail water in the inner cavity flows through the filtering gap through the annular flow guide plate, the fluid is evenly distributed through the annular flow guide plates arranged at equal distances, so as to avoid blockage or insufficient filtration caused by excessive local tail water flow rate, so that the small particles and suspended solids are intercepted by the filtering gap, and the tail water particles meeting the requirements can pass through the filtering gap, so as to ensure that the tail water reaches the best cleanliness before entering the recharge well, prevent blockage and reduce the recharge efficiency, at the same time, the filtering gap is trapezoidal, and the size of the gap gradually decreases from inside to outside, so that the filtering gap is not easy to be blocked and backwashing is more convenient, after the tail water is filtered by the wire-wound layer, the tail water enters the recharge well to complete the recharge process, and when the tail water flows out, the flow path of the tail water is guided through the second flow guide groove formed between the wire-wound layer and the sleeve, so as to reduce the turbulence and the resistance caused by the filtering structure to the tail water, and improve the flow rate and recharge amount of the tail water.
[0016] The application realizes the installation of filtering structures with different diameters by the stepped connecting piece, the bottom ends of the filling screen pipe assembly and the wire-wound screen pipe assembly are respectively provided with the first stepped connecting end and the second stepped connecting end, and are connected with the stepped connecting piece to complete the installation of the assembly, so that the screen pipe can be segmented and have different diameters to adapt to different formation permeability and optimize the flow rate distribution, and the graded filtration can improve the tail water recharge amount of the device, and the installation of the descaling device can be increased through the stepped connecting piece. BRIEF DESCRIPTION OF DRAWINGS
[0017] Figure 1 It is a whole structure schematic view of the application.
[0018] Figure 2 It is a tail water recharge flow direction structure schematic view of the application.
[0019] Figure 3 It is a filling screen pipe assembly structure schematic view of the application.
[0020] Figure 4 Structure diagram of the wire-wound screen assembly of the present application.
[0021] Figure 5 Structure diagram of the cross-section of the wire-wound screen assembly of the present application.
[0022] Figure 6 Structure diagram of the wire-wound screen assembly of the present application. Figure 2 Enlarged structure diagram of the structure at A.
[0023] The reference signs are: 1, casing pipe; 2, base pipe; 3, stepped connecting piece; 4, filling screen assembly; 41, perforated pipe; 42, filling filter layer; 43, first flow guide groove; 44, conical water inlet pipe; 45, outer protective sleeve; 46, first stepped connecting end; 5, wire-wound screen assembly; 51, center pipe; 52, longitudinal support rod; 53, wire-wound layer; 54, spiral flow guide ring; 55, annular flow guide plate; 56, second stepped connecting end; 57, second flow guide groove. DETAILED DESCRIPTION
[0024] The present application provides a sandstone thermal reservoir geothermal tail water reinjection device, as shown in Figure 1 - Figure 6 The present application provides a sandstone thermal reservoir geothermal tail water reinjection device, as shown in
[0025] Further, as shown in Figure 1 and Figure 3 The filling screen assembly 4 includes a perforated pipe 41 fixedly connected with the base pipe 2, the surface of the perforated pipe 41 is covered with a filling filter layer 42, the surface of the filling filter layer 42 is provided with a plurality of first flow guide grooves 43, the top end of the filling filter layer 42 is fixedly connected with a conical water inlet pipe 44, and the tail water enters the inner cavity of the filling screen assembly 4 through the conical water inlet pipe 44 after entering the base pipe 2. Since the inner cavity diameter of the conical water inlet pipe 44 gradually decreases, the tail water gradually shrinks the flow passage through the conical passage, accelerates the fluid, enhances the penetration of the tail water in the filling filter layer 42, and effectively improves the reinjection amount of the tail water.
[0026] Further, as shown in Figure 1 and Figure 4As shown, the wire-wrapped screen assembly 5 comprises a central pipe 51, a plurality of longitudinal support rods 52 are fixedly connected to the middle of the central pipe 51, the surfaces of the longitudinal support rods 52 are provided with a wire-wrapped layer 53, the surface of the wire-wrapped layer 53 is fixedly connected with a spiral flow guide ring 54, the inner walls of the longitudinal support rods 52 are collectively provided with a plurality of annular flow guide plates 55, the annular array of the longitudinal support rods 52 is uniformly distributed in the middle of the central pipe 51 to form a support structure, which serves as the framework of the wire-wrapped layer 53, supports and maintains the stability of the gaps of the wire-wrapped layer 53, and the tail water filtered by the wire-wrapped screen assembly 5 flows into the recharge well.
[0027] Further, as shown in Figure 1 and Figure 3 , the filling filter layer 42 is composed of multiple layers of filtering granular materials, and the two filling screen assemblies 4 are arranged in sequence from top to bottom, the filling filter layer 42 in the upper filling screen assembly 4 is made of relatively large filtering granular materials, and the filling filter layer 42 in the lower filling screen assembly 4 is made of fine filtering granular materials, after the tail water enters the inner cavity of the base pipe 2, it first flows into the upper filling screen assembly 4, the filling filter layer 42 with relatively large filtering granular materials intercepts the relatively large impurity particles in the tail water, preventing them from entering the lower filling screen assembly 4 or the recharge well, through the physical interception effect, the suspended solids and coarse particles in the tail water are effectively removed, the tail water after passing through the upper filling screen assembly 4 flows downward into the lower filling screen assembly 4, and the finer filtering granular materials in the lower filling screen assembly 4 filter the fine impurity particles that have not been filtered out in the upper filling screen assembly 4, further intercepting these fine impurity particles through finer filtering granular materials, using granular materials of different sizes to form a graded filter, gradually intercepting impurities of different sizes, reducing the risk of blockage of single-layer fillings, effectively improving the filtering precision of the structure, ensuring that the tail water reaches a higher degree of purity before entering the wire-wrapped screen assembly 5, and the filling filter layer 42 does not use magnets, electricity or additives during use, is easy to install and maintain, and the treated fluid does not pass through additives, causing no chemical pollution.
[0028] Further, as shown in Figure 3 , the surface of the filling filter layer 42 is sleeved with an outer protective sleeve 45, the first flow guide groove 43 is located between the filling filter layer 42 and the outer protective sleeve 45, and a plurality of through holes are formed in the surfaces of the perforated pipe 41 and the outer protective sleeve 45, the tail water flows through the filling filter layer 42 for filtering treatment through the through holes, and the flow rate of the tail water in the filling filter layer 42 is increased through the plurality of first flow guide grooves 43 to avoid blockage of large impurity particles in the filling filter layer 42, affecting the flow of the tail water.
[0029] Further, as shown in Figure 4 , Figure 5 and Figure 6, the winding interval of the wire-wound layer 53 is the same, and the filter gap is formed between the adjacent two turns of the wire-wound layer 53, the cross section of the filter gap is trapezoidal, the wire-wound layer 53 forms the screen structure of the continuous spiral filter gap through the arranged gap, and meanwhile, the winding interval of the wire-wound layer 53 can be adjusted according to the required tail water cleanliness, and the smaller the winding interval is, the smaller the passable particles are.
[0030] Further, as shown in Figure 6 , the wire-wound layer 53 is made of stainless steel wire and has a trapezoidal cross section, the wire-wound layer 53 made of stainless steel material can better adapt to the acidic, alkaline and high-temperature environment, and the filter gap formed by the trapezoidal stainless steel wire is also trapezoidal, and the size of the gap gradually decreases from the inside to the outside, so that the filter gap is not easy to be blocked and backwashing is more convenient.
[0031] Further, as shown in Figure 5 and Figure 6 , the cross section of the annular flow guide plate 55 is triangular, and the size of the cross section gradually decreases from the inner wall to the wire-wound layer 53, and a plurality of annular flow guide plates 55 are arranged at equal distances, the positions of the annular flow guide plates 55 correspond to the positions of the filter gaps, the tail water filtered by the two-layer filling type screen pipe assembly 4 enters the inner cavity of the wire-wound screen pipe assembly 5, and the tail water in the inner cavity flows through the filter gap through the annular flow guide plate 55, the fluid is uniformly distributed through a plurality of annular flow guide plates 55 arranged at equal distances, so as to avoid local tail water flow rate being too large to cause blockage or insufficient filtration, so that the micro particles and suspended matters are intercepted by the filter gap, and the tail water particles meeting the requirements can pass through the filter gap, so as to ensure that the tail water reaches the best cleanliness before entering the recharge well, prevent blockage and reduce the recharge efficiency, and after the tail water is filtered by the wire-wound layer 53, the tail water enters the recharge well to complete the recharge process.
[0032] Further, as shown in Figure 2 and Figure 6 , the spiral flow guide ring 54 is located between the wire-wound layer 53 and the sleeve 1, and the second flow guide groove 57 is formed between the adjacent two turns of the spiral flow guide ring 54, the tail water filtered through the wire-wound layer 53 flows into the recharge well, and when the tail water flows out, the flow path of the tail water is guided through the second flow guide groove 57 formed between the wire-wound layer 53 and the sleeve 1, so as to reduce the turbulence and the resistance of the filter structure to the tail water, and improve the flow rate and recharge amount of the tail water.
[0033] Further, as shown in Figure 1 , Figure 5 and Figure 6As shown, the bottom end of the perforated pipe 41 is fixedly connected with the first stepped connecting end 46, and the bottom end of the center pipe 51 is fixedly connected with the second stepped connecting end 56. The first stepped connecting end 46 and the second stepped connecting end 56 are adapted to the position and shape of the stepped connecting piece 3, and are mechanically connected (such as internal hexagonal bolt fastening + surface welding) or structurally integrated (such as the wire-wound screen pipe assembly 5 and the base pipe 2 being integrally welded) with the stepped connecting piece 3. According to the specific position of the target recharge layer, the filling screen pipe assembly 4 with larger filtering particles, the filling screen pipe assembly 4 with finer filtering particles, and the wire-wound screen pipe assembly 5 are sequentially installed from top to bottom. According to the specific diameter of each assembly, the appropriate connecting position on the first stepped connecting end 46 and the second stepped connecting end 56 is selected, so that the screen pipe can be segmented with different diameters to adapt to different formation permeability and optimize the flow rate distribution. Meanwhile, the staged filtering mode can improve the tail water recharge amount of the device, and the installation of the descaling device can be increased through the stepped connecting piece 3.
[0034] Further, the intersection of the longitudinal support rod 52 and the wire-wound layer 53 is connected by welding. The welding process can increase the overall strength of the wire-wound screen pipe assembly 5 and withstand high pressure or mechanical impact.
[0035] The working principle of the present application is as follows: firstly, the sleeve 1 is inserted into the recharge well to fix the well wall, prevent the stratum from collapsing, and provide installation space for the screen pipe; then, two filling screen pipe assemblies 4 and a wire-wound screen pipe assembly 5 are fixed on the base pipe 2 in sequence, and the two filling screen pipe assemblies 4 and the wire-wound screen pipe assembly 5 are connected with the stepped connecting piece 3 through the first stepped connecting end 46 and the second stepped connecting end 56, respectively, by mechanical connection (such as internal hexagonal bolt fastening + surface welding) or structural integration (such as integral welding of the wire-wound screen pipe assembly 5 and the base pipe 2); according to the specific position of the target recharge layer, the filling screen pipe assembly 4 with larger filtering particles, the filling screen pipe assembly 4 with finer filtering particles, and the wire-wound screen pipe assembly 5 are installed in sequence from top to bottom; according to the specific diameter of each assembly, the appropriate connecting position on the first stepped connecting end 46 and the second stepped connecting end 56 is selected, so that the screen pipe can be segmented with different diameters to adapt to different stratum permeability and optimize the flow velocity distribution; at the same time, the graded filtering mode can improve the tail water recharge capacity of the device; in addition, the installation of the descaling device can be increased through the stepped connecting piece 3; after the structural installation is completed, the tail water to be recharged is added to the base pipe 2; after the tail water enters the inner cavity of the base pipe 2, it first flows into the upper filling screen pipe assembly 4; the filling filter layer 42 with larger filtering particles in the upper filling screen pipe assembly 4 intercepts larger particle impurities in the tail water to prevent them from entering the lower filling screen pipe assembly 4 or the recharge well; through the action of physical interception, the suspended solids and coarse particles in the tail water are effectively removed; the tail water after the upper filling screen pipe assembly 4 flows downward into the lower filling screen pipe assembly 4; the finer filtering particles in the lower filling screen pipe assembly 4 filter the fine particle impurities that have not been filtered out in the upper filling screen pipe assembly 4; through finer filtering particles, these fine impurity particles are further intercepted; different sizes of particles are used to form graded filtering to gradually intercept impurities of different sizes, reduce the risk of blockage of single-layer filling, effectively improve the filtering precision of the structure, and ensure that the tail water reaches a higher degree of cleanliness before entering the wire-wound screen pipe assembly 5; the filling filter layer 42 does not use magnetism, electricity, or additives during use; the installation and maintenance are relatively simple; the treated fluid does not pass through additives, which will not cause any chemical pollution; the tail water flows through the filling filter layer 42 for filtering treatment through the through holes; at the same time, the flow rate of the tail water in the filling filter layer 42 is increased through the first flow guide grooves 43 to avoid blockage of larger particle impurities in the filling filter layer 42, which affects the flow of the tail water; the tail water filtered by the two-layer filling screen pipe assembly 4 enters the inner cavity of the wire-wound screen pipe assembly 5; the tail water in the inner cavity flows through the filter gap through the annular flow guide plate 55; the fluid is evenly distributed through the annular flow guide plates 55 arranged at equal distances to avoid blockage or insufficient filtering caused by excessive local tail water flow rate, so that the micro-particles and suspended solids are intercepted by the filter gap, and the tail water particles meeting the requirements can pass through the filter gap to ensure that the tail water reaches the best cleanliness before entering the recharge well, preventing blockage and reducing the recharge efficiency; after the tail water is filtered through the wire-wound layer 53, it enters the recharge well.The recharging process is completed, and when the water flows out, the flow path of the tail water is guided through the second flow guide groove 57 formed between the wire winding layer 53 and the sleeve 1, the turbulence is reduced, and the recharging amount of the tail water is improved.
[0036] It is to be understood that the present application is described by way of example only, and that modifications or alterations can be made to the features and embodiments described without departing from the spirit or scope of the application as set out in the claims. In addition, modifications can be made to the features and embodiments described to suit particular circumstances and materials without departing from the spirit and scope of the application. Accordingly, the application is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims are intended to be within the scope of the application.
Claims
1. A sandstone geothermal tailwater reinjection device, comprising a casing (1) and a base pipe (2) inserted into its inner cavity, characterized in that: The inner wall of the sleeve (1) is fixedly connected with several stepped connectors (3), and the base pipe (2) is provided with two filled screen pipe assemblies (4) for scale prevention. The bottom end of the base pipe (2) is fixedly connected to a wire-wound screen pipe assembly (5) for drainage. The filled screen tube assembly (4) includes a perforated tube (41) that is fixedly connected to the base tube (2). The surface of the perforated tube (41) is covered with a filled filter layer (42). The surface of the filled filter layer (42) is provided with a plurality of first guide grooves (43). A conical water inlet pipe (44) is fixedly connected to the top of the filled filter layer (42). The wire-wound screen tube assembly (5) includes a central tube (51), a number of longitudinal support rods (52) are fixedly connected to the middle of the central tube (51), a wire-wound layer (53) is wound around the surface of the number of longitudinal support rods (52), a spiral guide ring (54) is fixedly connected to the surface of the wire-wound layer (53), and a number of annular guide plates (55) are provided on the inner wall of the number of longitudinal support rods (52).
2. The sandstone geothermal tailwater reinjection device according to claim 1, characterized in that: The filling filter layer (42) is composed of multiple layers of filter particle material. The two filling screen tube assemblies (4) are arranged from top to bottom. The filling filter layer (42) in the upper filling screen tube assembly (4) is made of larger filter particle material, while the filling filter layer (42) in the lower filling screen tube assembly (4) is made of fine filter particle material.
3. The sandstone geothermal tailwater reinjection device according to claim 1, characterized in that: The surface of the filling filter layer (42) is covered with an outer protective sleeve (45), the first guide groove (43) is located between the filling filter layer (42) and the outer protective sleeve (45), and the surfaces of the perforated tube (41) and the outer protective sleeve (45) are provided with several through holes.
4. The sandstone geothermal tailwater reinjection device according to claim 1, characterized in that: The winding spacing of the winding layers (53) is the same, and a filter gap is formed between two adjacent winding layers (53), and the cross-section of the filter gap is trapezoidal.
5. A sandstone geothermal tailwater reinjection device according to claim 1, characterized in that: The winding layer (53) is made of stainless steel wire and has a trapezoidal cross-section.
6. The sandstone geothermal tailwater reinjection device according to claim 1, characterized in that: The cross-section of the annular guide plate (55) is triangular, and the size of the cross-section gradually decreases from its inner wall toward the winding layer (53). Several annular guide plates (55) are arranged at equal intervals, and the position of the annular guide plate (55) corresponds to the position of the filter gap.
7. A sandstone geothermal tailwater reinjection device according to claim 1, characterized in that: The spiral guide ring (54) is located between the winding layer (53) and the sleeve (1), and a second guide groove (57) is formed between two adjacent spiral guide rings (54).
8. A sandstone geothermal tailwater reinjection device according to claim 1, characterized in that: The bottom end of the perforated tube (41) is fixedly connected to a first stepped connecting end (46), and the bottom end of the central tube (51) is fixedly connected to a second stepped connecting end (56). The first stepped connecting end (46) and the second stepped connecting end (56) are adapted to the position and shape of the stepped connecting piece (3).
9. A sandstone geothermal tailwater reinjection device according to claim 1, characterized in that: The intersection of the longitudinal support rod (52) and the wire winding layer (53) is connected by welding.