Multi-layer sand control polymer screen pipe for weakly cemented reservoir and preparation method of multi-layer sand control polymer screen pipe

Abstract

The invention relates to the technical field of sand prevention, and discloses a multi-layer sand prevention polymer screen pipe for a weakly cemented reservoir. The waterproof layer is arranged on the outer side of the base pipe, the waterproof layer is used for being arranged in a pure water interlayer of a reservoir, the waterproof layer is made of a polymer, and the waterproof layer is of a consolidation body structure; the sand control layer structure is arranged on the outer side of the base pipe, the sand control layer structure is used for being arranged on a reservoir to be mined, the sand control layer structure is made of polymers, and the sand control layer structure is of a porous medium structure. The sand control screen pipe can be provided with a corresponding sand control layer structure and a waterproof layer according to the characteristics of an actual reservoir, and the problem that the productivity is reduced due to the fact that a large amount of water flows out of a water-containing interlayer is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of sand control, and more specifically, to a multi-layer sand control polymer screen pipe for weakly cemented reservoirs and a preparation method thereof. Background Art

[0002] There are a large number of weakly cemented oil and gas reservoirs distributed in the South my country Sea, the most typical of which are the natural gas hydrates in the Shenhu Sea area and the shallow natural gas reservoirs. The efficient exploitation of such oil and gas resources is of great strategic significance to China, which is poor in oil and gas. However, the weakly cemented reservoirs in the South China Sea have a high mud content and a small formation sand particle size, which poses a greater risk of sand production. In addition, sand control safety and mining efficiency often present a contradictory relationship of one increasing while the other decreases. How to balance the relationship between sand control and stable production in the production process and achieve scientific, accurate and efficient sand control is a key technical issue that the weakly cemented oil and gas reservoirs in the South China Sea will inevitably face in future commercial exploitation.

[0003] Existing sand-proof screens mostly use conventional media such as pre-filled gravel, regular seam nets, and regular filter screens as sand-retaining structures. The sand-retaining effect of such sand-proof media depends on the accurate selection of sand-proof precision. If the sand-proof precision is too low, a large amount of formation sand will enter the wellbore, causing equipment damage, wellbore blockage and other underground accidents that affect normal mining; if the sand-proof precision is too high, it is easy to cause blockage of the sand-proof medium, reduce production efficiency, and even completely stop oil and gas production. However, for the weakly cemented reservoirs in the South China Sea with a high clay content, since different types of clay minerals have different microscopic morphologies and migration characteristics, the sand-proof precision selection method used in conventional reservoirs is not completely applicable here. The selection of sand-proof medium precision needs to be based on a highly accurate understanding of formation information such as reservoir sand particle size and clay content, and has an empirical formula with a high degree of adaptability to the formation. In addition, hydrates or natural gas are often stored in the reservoir in the form of thin layers. These thin layers have different thicknesses and properties, and there are pure water-containing interlayers between the layers. The large amount of water produced by the water-containing interlayers during the production process will inevitably affect the efficiency of gas production. Therefore, if such vertically highly anisotropic reservoirs are generally sand-controlled, the most efficient production will inevitably not be achieved. In summary, there is currently no sand-control technology that is highly compatible with the weakly cemented reservoirs in the South China Sea. Summary of the invention

[0004] The purpose of the present invention is to provide a multi-layer sand control polymer screen for weakly cemented reservoirs and a preparation method thereof, so as to solve the problems existing in the prior art.

[0005] To achieve the above-mentioned purpose, the present invention provides the following scheme: The present invention provides a multi-layer sand-proof polymer screen pipe for weakly cemented reservoirs, comprising: a base pipe; a waterproof layer, arranged on the outside of the base pipe, the waterproof layer is used to be arranged in a pure water interlayer of the reservoir, the material of the waterproof layer is a polymer, and the waterproof layer is a consolidated body structure; a sand-proof layer structure, arranged on the outside of the base pipe, the sand-proof layer structure is used to be arranged in a reservoir to be mined, the material of the sand-proof layer structure is a polymer, and the sand-proof layer structure is a porous medium structure.

[0006] Furthermore, the waterproof layer is structurally bonded to the sand control layer.

[0007] Furthermore, the sand control layer structure includes at least one sand control layer; wherein the number of layers of the sand control layer is determined based on the particle size information of the reservoir to be mined.

[0008] Furthermore, the sand control layer structure includes a first sand control layer and a second sand control layer, and the second sand control layer is sleeved on the outside of the first sand control layer.

[0009] Furthermore, the pore radius of the first sand control layer is smaller than that of the second sand control layer.

[0010] Furthermore, it also includes an outer protective layer which is sleeved on the outer side of the waterproof layer and the anti-sand layer structure.

[0011] A method for preparing a multi-layer sand-proof polymer screen for a weakly cemented reservoir comprises the following steps: sleeve an inner casing on the inner side of the base pipe, and sleeve a first outer casing on the outer side of the base pipe; configure the polymer required for the sand-proof layer structure, and inject it into the annulus between the base pipe and the first outer casing after fully stirring, and remove the inner casing and the first outer casing after initial setting, and wait for complete consolidation to form the sand-proof layer structure; sleeve an inner casing on the inner side of the base pipe with the sand-proof layer structure, and sleeve a second outer casing on the outer side of the base pipe; configure the polymer required for the waterproof layer, and inject it into the annulus between the base pipe and the second outer casing after fully stirring, and remove the inner casing and the second outer casing after initial setting, and wait for complete consolidation to form the waterproof layer.

[0012] Furthermore, a polymer required for the first sand control layer is prepared, and the polymer is fully stirred before being injected into the annulus between the base pipe and the first outer casing. After the slurry is initially solidified, the inner casing and the first outer casing are withdrawn, and the first sand control layer is formed after the slurry is completely solidified; the second outer casing is sleeved on the outer side of the base pipe with the first sand control layer; a polymer required for the second sand control layer is prepared, and the polymer is fully stirred before being injected into the annulus between the first sand control layer and the second outer casing. After the slurry is initially solidified, the second outer casing is withdrawn, and the second sand control layer is formed after the slurry is completely solidified.

[0013] The present invention discloses the following technical effects:

[0014] In the present invention, a waterproof layer and a sand control layer structure are arranged on the outside of the base pipe, wherein the waterproof layer and the sand control layer structure are both composed of different polymers, replacing conventional mechanical sand control media. When in use, the waterproof layer is located in the pure aquifer of the reservoir, and is guaranteed to be impermeable in the form of its consolidated body structure, and the sand control layer structure is located in the reservoir to be mined, and plays a blocking effect in the form of a porous medium. Based on the evaluation of the sand control effect, it can be seen that it has a good sand blocking effect on clay minerals and quartz sand of fine sand grade and has low permeability damage, and the overall structure is highly compatible with the weakly cemented reservoir in the South China Sea.

[0015] The porous medium formed after the polymer is solidified has high porosity, strong pore connectivity and a complex pore network. Based on the results of a large number of indoor experiments conducted by the inventors to evaluate the sand control effect of this material, the present invention has a good sand control effect on fine sand clay minerals and quartz sand with low permeability damage.

[0016] It can achieve precise sand control under complex formation conditions, and effectively prevent sand while avoiding the problem of large amounts of water coming out of high-water-content interlayers affecting gas production efficiency;

[0017] The present application is simple to prepare and has a streamlined structure. Different parts are connected by relying on the material's own bonding strength, and no additional fastening mechanism or separation mechanism is required. This increases the life of the sand control screen, reduces maintenance costs, and avoids sand control failure due to erosion and damage of the separator, thereby increasing the overall reliability of the screen. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0020] Figure 2 Schematic diagram of the layered preparation for sand control screens;

[0021] Figure 3 The test results for evaluating the sand control effect of sand consolidation bodies;

[0022] Figure 4 The experimental results for evaluating the sand control effect of pre-packed gravel are provided;

[0023] Among them, 1. base pipe; 2. waterproof layer; 3. first sand control layer; 4. second sand control layer; 5. protective layer; 6. inner casing; 7. first outer casing; 8. second outer casing; 9. water-containing interlayer; 10. reservoir. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] like Figure 1 and Figure 2 As shown, the present invention provides a multi-layer sand-proof polymer screen pipe for weakly cemented reservoirs, comprising: a base pipe 1; a waterproof layer 2, arranged outside the base pipe 1, used to be arranged in a pure water interlayer of a reservoir 10, the material of the waterproof layer 2 is a polymer, and the waterproof layer 2 is a consolidation structure; a sand-proof layer structure, arranged outside the base pipe 1, used to be arranged in a reservoir 10 to be mined, the material of the sand-proof layer structure is a polymer, and the sand-proof layer structure is a porous medium structure. The waterproof layer 2 is adhered to the sand-proof layer structure.

[0027] The sand control layer structure includes at least one sand control layer. The number of sand control layers depends on the particle size distribution and sorting of the formation sand. For some reservoirs 10 with relatively concentrated particle sizes, a single layer of sand control medium can meet the sand control requirements in the radial direction, and a single layer of sand control layer structure can be used.

[0028] In this embodiment, the sand control layer structure includes a first sand control layer 3 and a second sand control layer 4. The first sand control layer 3 is arranged on the outside of the base pipe 1, and the second sand control layer 4 is arranged on the outside of the first sand control layer 3. The waterproof layer 2 is arranged on the outside of the base pipe 1 and is located on the top of the first sand control layer 3 and the second sand control layer 4. A protective layer 5 is arranged on the outside of the waterproof layer 2 and the second sand control layer 4.

[0029] The base pipe 1 is made of a seamless steel pipe with holes, and the material is ordinary carbon steel such as J55, N80, P110, with a pore size of 10mm and a pore density of 50-100 holes / m. The protective layer 5 is a single-layer metal mesh, made of 304 stainless steel, with a thickness of 0.5-1mm and a mesh size of 10-20. It is worth noting that the sand and water-proof functions of the present invention are mainly realized by the first sand-proof layer 3, the second sand-proof layer 4 and the waterproof layer 2. Therefore, the present invention does not have too many requirements on the properties of the base pipe 1 and the outer protective layer 5. The two only need to meet the requirements in terms of strength and avoid clogging as much as possible.

[0030] The waterproof layer 2, the first sand control layer 3 and the second sand control layer 4 are all polymers, which are arranged on the ground and filled in the corresponding positions in the form of slurry before solidification, and the adhesion of different parts of the screen pipe is achieved by relying on their own bonding strength, without the need for additional fastening and separation mechanisms.

[0031] The first sand control layer 3 is arranged in the annulus formed between the base pipe 1 and the first outer casing 7. When filling the first sand control layer 3, the inner casing 6 is inserted into the base pipe 1, and the first outer casing 7 is fixed outside the base pipe 1. At this time, an annulus is formed between the base pipe 1 and the first outer casing 7, and the polymer of the first sand control layer 3 is filled into the annulus. After the slurry is solidified, the first sand control layer 3 is formed. The first sand control layer 3 is a porous medium with both mechanical strength and high conductivity. It has high porosity, high pore connectivity and a complex pore network. It can effectively prevent sand while greatly reducing the risk of blockage.

[0032] The second sand control layer 4 is arranged in the annulus formed between the first sand control layer 3 and the second outer casing 8. The second outer casing 8 is fixed outside the base pipe 1 and the first sand control layer 3. The polymer of the second sand control layer 4 is filled into the annulus between the first sand control layer 3 and the second outer casing 8. The second sand control layer 4 is formed after the slurry is solidified. The second sand control layer 4 is a porous medium with both mechanical strength and high conductivity. It has high porosity, high pore connectivity and a complex pore network. It can effectively prevent sand while greatly reducing the risk of blockage.

[0033] The porous medium formed after the polymer consolidation of the first sand control layer 3 and the second sand control layer 4 has stable and adjustable pore size, pore structure and porosity, and the pore radius of the first sand control layer 3 is smaller than the pore radius of the second sand control layer 4. The second sand control layer 4 is used to block the coarser components of mud and sand in the formation, and the first sand control layer 3 is used to further block the finer components of mud and sand in the formation.

[0034] The thickness of the waterproof layer 2 , the first sand control layer 3 and the second sand control layer 4 completely depends on the thickness of the water-bearing interlayer 9 and the reservoir 10 .

[0035] The waterproof layer 2 is arranged in the annulus formed between the base pipe 1 and the second outer casing 8, and is located above the first sand control layer 3 and the second sand control layer 4. When filling the waterproof layer 2, the inner casing 6 is inserted into the base pipe 1, and the second outer casing 8 is fixed outside the base pipe 1. The polymer of the waterproof layer 2 is filled in the annulus at the top of the first sand control layer 3 and the second sand control layer 4, and the waterproof layer 2 is formed after the slurry solidifies. The waterproof layer 2 corresponds to the water-containing interlayer 9 between the reservoirs 10, and does not involve the production of gas. Its function is to completely block the production of water and sand. The first sand control layer 3 and the second sand control layer 4 correspond to the reservoir 10 to be mined. It is necessary to ensure the sand control effect while preventing the gas production channel from being blocked by mud and sand as much as possible. Based on the above different functional requirements, the polymer formulas of the waterproof layer 2, the first sand control layer 3 and the second sand control layer 4 are adjusted respectively, so that the polymer of the waterproof layer 2 will form a high-strength and impermeable solid body after solidification, which is used to block the production of water in the high-water-containing interlayer 9; the polymers of the first sand control layer 3 and the second sand control layer 4 will form a porous medium with both mechanical strength and high conductivity after solidification, which has high porosity, high pore connectivity and a complex pore network, which can effectively prevent sand while greatly reducing the risk of blockage.

[0036] The outer diameter of the inner sleeve 6 needs to be equal to or slightly smaller than (not exceeding 1 mm) the inner diameter of the base pipe 11, and the wall thickness is 1-2 mm; the inner diameters of the first outer sleeve 7 and the second outer sleeve 8 depend on the radial thickness of the first sand control layer 3 and the second sand control layer 4, and the wall thickness is 1-2 mm; the inner sleeve 6, the first outer sleeve 7 and the second outer sleeve 8 only play a supporting and shaping role before the slurry of the present invention solidifies, and there are no special requirements on the material. A low-cost material that is not easy to bond with the slurry can be selected, such as a PVC cylindrical tube.

[0037] A method for preparing a multi-layer sand control polymer screen for a weakly cemented reservoir, the specific steps are as follows:

[0038] An inner casing 6 is sleeved on the inner side of the base pipe 1;

[0039] Prepare the polymer required for the sand control layer structure, fully stir it and inject it into the annulus between the base pipe 1 and the first outer casing, remove the inner casing 6 and the first outer casing 7 after initial setting, and wait for complete consolidation to form the sand control layer structure;

[0040] An inner casing 6 is sleeved inside the base pipe 1 with the sand control layer structure, and a second outer casing is sleeved outside the base pipe 1;

[0041] Prepare the polymer required for the waterproof layer 2, stir it thoroughly and evenly, then inject it into the annulus between the base pipe 1 and the second outer casing 8. After initial setting, remove the inner casing 6 and the second outer casing 8, and wait for complete solidification to form the waterproof layer 2.

[0042] Specifically, the polymer required for the first sand control layer 3 is prepared, fully stirred and then injected into the annulus between the base pipe 1 and the first outer casing 7, and after initial setting, the inner casing 6 and the first outer casing 7 are removed, and the first sand control layer 3 is formed after the slurry is completely solidified.

[0043] Place the base pipe 1 with the first sand control layer 3, the outer protective layer 5 and the second outer casing 8, prepare the polymer required for the second sand control layer 4, and inject it into the annulus between the first sand control layer 3 and the second outer casing 8 after fully stirring. After initial setting, remove the second outer casing 8 and wait for complete solidification to form the second sand control layer 4.

[0044] An inner casing 6, a base pipe 1 with a first sand control layer 3 and a second sand control layer 4, an outer protective layer 5 and a second outer casing 8 are placed, and the polymer required for the waterproof layer 2 is prepared. After being fully stirred, it is injected into the annulus between the base pipe 1 and the second outer casing 8. After initial setting, the inner casing 6 and the second outer casing 8 are removed. After waiting for complete consolidation to form the waterproof layer 2, the sand control screen is completed.

[0045] The volume of the polymer in the present application remains substantially unchanged before and after solidification, and the amount of polymer injected in all steps depends on the volume of the required sand control medium.

[0046] The sand-control screen provided in the present application replaces the conventional mechanical sand-control medium with a multi-layer polymer. The porous medium formed after the polymer is solidified has high porosity, strong pore connectivity and a complex pore network. The sand-control medium used in the present application has a good sand-retaining effect on fine sand-grade clay minerals and quartz sand, and has low permeability damage. The present application is simple to prepare and has a streamlined structure. Different parts are connected by the material's own bonding strength, and no additional fastening and separation mechanisms are required. The present application can be applied to complex formations with strong interlayer anisotropy to achieve precise sand control, that is, while achieving efficient sand control, it also avoids the problem of large amounts of water coming out of the high-water-content interlayer 9 affecting gas production efficiency.

[0047] like Figure 3 , Figure 4 As shown, the sand control effect evaluation experiments of quartz sand and illite were carried out using the sand control consolidation body of the present invention and conventional pre-filled gravel, respectively. The median particle size of quartz sand and illite used in the experiment was 10μm. (a) The pseudo-permeability refers to the ratio of the real-time permeability of the sand control medium to the initial permeability. The smaller the pseudo-permeability, the greater the permeability damage; (b) shows the experimental sand output in different time periods (1 hour, 2 hours, 3 hours, 4 hours and 5 hours). The smaller the sand output, the better the sand control effect. The experimental results show that the sand control consolidation body used in the present invention has an excellent blocking effect on muddy sand of fine sand level, and compared with traditional gravel sand control, it basically does not cause permeability damage during the sand control process, and the risk of clogging is relatively small.

[0048] In the description of the present invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0049] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A multi-layer sand control polymer screen for weakly cemented reservoirs, characterized in that: include: Base tube (1); A waterproof layer (2) is arranged on the outside of the base pipe (1), the waterproof layer (2) is used to be arranged in a pure water interlayer of the reservoir (10), the material of the waterproof layer (2) is a polymer, and the waterproof layer (2) is a solid body structure; A sand control layer structure is arranged outside the base pipe (1), the sand control layer structure is used to be arranged in a reservoir to be mined, the material of the sand control layer structure is a polymer, and the sand control layer structure is a porous medium structure.

2. The multi-layer sand control polymer screen for weakly cemented reservoirs according to claim 1, characterized in that: The waterproof layer (2) is structurally bonded to the sand control layer.

3. The multi-layer sand control polymer screen for weakly cemented reservoirs according to claim 1, characterized in that: The sand control layer structure comprises at least one sand control layer; Wherein, the number of layers of the sand control layer is determined based on the particle size information of the reservoir to be mined.

4. The multi-layer sand control polymer screen for weakly cemented reservoirs according to claim 1, characterized in that: The sand control layer structure comprises a first sand control layer (3) and a second sand control layer (4), wherein the second sand control layer (4) is sleeved on the outer side of the first sand control layer (3).

5. The multi-layer sand control polymer screen for weakly cemented reservoirs according to claim 4, characterized in that: The first sand control layer (3) has a pore radius smaller than that of the second sand control layer (4).

6. The multi-layer sand control polymer screen for weakly cemented reservoirs according to claim 5, characterized in that: It also includes an outer protective layer (5) sleeved on the outer sides of the waterproof layer (2) and the sand control layer structure.

7. A method for preparing a multi-layer sand control polymer screen for weakly cemented reservoirs, characterized in that: The method for preparing the multi-layer sand control polymer screen for weakly cemented reservoirs according to any one of claims 1 to 6 comprises the following steps: An inner sleeve (6) is sleeved on the inner side of the base pipe (1), and a first outer sleeve (7) is sleeved on the outer side of the base pipe (1); The polymer required for the sand control layer structure is prepared, fully stirred and then injected into the annulus between the base pipe (1) and the first outer casing (7), and after initial setting, the inner casing (6) and the first outer casing (7) are removed, and the sand control layer structure is formed after complete solidification; An inner casing (6) is sleeved on the inner side of a base pipe (1) having the sand control layer structure, and a second outer casing (8) is sleeved on the outer side of the base pipe (1); The polymer required for the waterproof layer (2) is prepared, stirred thoroughly and then injected into the annulus between the base pipe (1) and the second outer casing (8), and after initial setting, the inner casing (6) and the second outer casing (8) are removed, and the waterproof layer (2) is formed after complete solidification.

8. The method for preparing a multi-layer sand control polymer screen for a weakly cemented reservoir according to claim 7, characterized in that: The sand control layer structure comprises a first sand control layer (3) and a second sand control layer (4), wherein the second sand control layer (4) is sleeved on the outside of the first sand control layer (3), a polymer required for the sand control layer structure is prepared, fully stirred and then injected into the annulus between the base pipe (1) and the first outer casing (7), and after initial setting, the inner casing (6) and the first outer casing (7) are removed, and the sand control layer structure is formed after waiting for complete consolidation, and the method further comprises: The polymer required for the first sand control layer (3) is prepared, fully stirred and then injected into the annulus between the base pipe (1) and the first outer casing (7), and after initial setting, the inner casing (7) and the first outer casing (7) are removed, and the first sand control layer (3) is formed after complete solidification; The second outer casing (8) is sleeved on the outer side of the base pipe (1) with the first sand control layer (3); The polymer required for the second sand control layer (4) is prepared, fully stirred and then injected into the annulus between the first sand control layer (3) and the second outer casing (8), and the second outer casing (8) is removed after initial setting, and the second sand control layer (4) is formed after complete solidification.

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