Flow control screens for oil wells

Abstract

The present invention relates to a flow control screen for an oil well, which has an adjustable flow conductivity. The flow control screen of the present invention includes one or more fluid valves, each of which has a respective predetermined opening threshold and is configured to open when the fluid pressure difference between the fluid pressure on the first side of the fluid valve and the fluid pressure on the second side of the fluid valve is greater than or equal to the respective predetermined opening threshold, so as to open the corresponding fluid channel. The present invention also relates to an oil well structure having the flow control screen, a method for operating the oil well structure, and a method for modifying the oil well structure.

Description

Technical Field

[0001] The invention relates to a flow control screen for an oil well, which has adjustable flow conductivity, an oil well structure having the flow control screen and a method for operating the oil well structure. Background Art

[0002] In the development of oil fields, due to the heterogeneity of the oil fields and the difference in oil-water viscosity, the degree of fracture development is different, and the permeability of each section of the formation is also very different. After a period of production in the oil field, water will be produced locally, and 100% water will be produced in the local water-producing area. For example, a well in a certain oil field has a horizontal section of 800 meters long, 80 meters of which is a high permeability section, and the other sections are low permeability sections. The underground viscosity of crude oil is 100 centipoise, the viscosity of water is 1 centipoise, and the oil-water viscosity ratio is 100. Once water is produced in the high permeability section, the water content of the produced fluid is as high as, for example, 90%. After the water is produced, the oil production will drop sharply, for example, causing the daily oil production to drop from 35 cubic meters / day when the well was opened to less than 7 cubic meters / day, causing huge losses to the oil field, so the development of oil fields urgently needs technical measures to reduce water and increase oil. At present, the most effective measure for reducing water and increasing oil is segmented flow control technology. Commonly used segmented flow control technologies include segmented flow control using discrete packers and flow control screens, and segmented flow control using continuous packers and flow control screens. On the one hand, separate packers or continuous packers are used to block the axial flow of high-flow water in the high-permeability section, and cross-flow will not form. On the other hand, the amount of water flowing radially into the flow control screen is limited by the flow control nozzle of the flow control screen, so that the amount of water entering the wellbore is controlled, while the liquid production at the wellhead remains unchanged. Therefore, the production pressure difference can be increased, thereby increasing the oil production of the oil-producing section, which plays a role in reducing water and increasing oil production.

[0003] The current segmented flow control technology has the following problems that need to be solved. In the initial stage of exploitation, when the water-producing section accounts for a small proportion of the entire well section (for example, only 10% of the entire well section), flow-limiting isolation can achieve the purpose of controlling water and increasing oil production. In the later stage of exploitation, as more and more well sections, or even the entire well section, are flooded to varying degrees, water is needed to carry oil, that is, it is necessary to increase the flow rate from the formation into each flow control screen. However, since each flow control screen is equipped with a flow-limiting mechanism, the liquid production of the formation corresponding to each flow control screen cannot be increased, resulting in insufficient oil being brought out by water. At this time, the flow-limiting valve on the flow control screen needs to be increased, otherwise the pressure on the flow-limiting valve is too high, the pressure on the formation is too small, and the formation liquid production is low, which cannot meet the requirements of liquid lifting and oil increase in the later stage of oil well production. In addition, the flow-limiting valve needs to be increased in stages. For example, when the water content rises to a certain level (such as 50% water content), the flow limiting valve needs to be adjusted to 1 times larger; when the water content rises further (such as rising to 98% water content), the flow limiting valve needs to be adjusted to 1 times larger. However, it is a difficult problem to realize the step-by-step opening of the flow limiting valve several thousand meters underground. At present, the commonly used method is to install a sliding sleeve in the tubing, and then use a special tool to open the sliding sleeve to go down from the wellhead, go down to the position of the sliding sleeve several thousand meters underground, push the sliding sleeve open, and thus adjust the flow control screen's conductivity. However, this method must bring out an electric pump and the production tubing above it, which is expensive and time-consuming. In addition, it is necessary to connect several thousand meters of tubing to open the sliding sleeve, which consumes a lot of manpower and material resources and delays the production of the oil well.

[0004] Therefore, in the art, there is a need to conveniently and easily implement phased and step-by-step adjustment of the flow control screen conductivity, so as to ensure the daily oil production of the oil well during the entire production period and extend the effective production time of the oil well. Summary of the invention

[0005] According to one aspect of the present invention, there is provided a flow control screen for an oil well, comprising: a hollow base pipe, the base pipe comprising a pipe wall impermeable to fluid, the pipe wall of the base pipe defining an inner cavity, the base pipe having one or more through holes formed in the pipe wall; a hollow filter pipe, the filter pipe comprising a pipe wall permeable to fluid, the filter pipe being arranged around the outer side of at least a portion of the base pipe, so that an annular space is formed between the filter pipe and the base pipe, one or more fluid channels being defined between the annular space and the inner cavity of the base pipe; and one or more fluid valves, each of the one or more fluid valves being arranged in a corresponding one of the one or more fluid channels, the one or more fluid valves being arranged in a corresponding one of the one or more fluid channels. Each of the plurality of fluid valves has a first side facing the inner cavity of the base pipe and a second side facing the annular space, wherein the one or more fluid valves are closed in an initial state to block the corresponding fluid passage, and wherein each of the one or more fluid valves has a respective predetermined opening threshold and is configured to open when a fluid pressure difference between a fluid pressure applied from the inner cavity of the base pipe to the first side of the fluid valve and a fluid pressure applied from the annular space to the second side of the fluid valve is greater than or equal to the respective predetermined opening threshold to open the corresponding fluid passage, so that the fluid in the annular space can flow into the inner cavity of the base pipe via the corresponding fluid passage.

[0006] In one embodiment, each of the one or more fluid valves is disposed in or near a corresponding one of the one or more through holes of the base pipe to block or allow fluid to enter the inner cavity of the base pipe through the through hole.

[0007] In one embodiment, the one or more through holes are arranged at intervals along the circumferential direction of the base pipe, or the one or more through holes are arranged at intervals along the longitudinal direction of the base pipe.

[0008] In one embodiment, the pipe wall of the base pipe includes a first section and an adjacent second section, the one or more through holes are formed in the first section at intervals in the circumferential direction, and the filter tube is arranged around the outside of at least a portion of the second section; and wherein the flow control screen further includes a hollow end ring, the end ring is assembled on the outside of at least a portion of the first section and connected to the filter tube, the pipe wall of the end ring has one or more axial holes and one or more radial holes, the one or more axial holes of the end ring are in fluid communication with the annular space, and each of the one or more radial holes of the end ring fluidly connects a corresponding one of the one or more axial holes of the end ring to a corresponding one of the one or more through holes of the base pipe, thereby defining the one or more fluid channels.

[0009] In one embodiment, each of the one or more fluid valves is disposed in a corresponding one of the one or more axial bores of the end ring.

[0010] In one embodiment, each of the one or more fluid valves includes: a first annular member, the first annular member facing the annular space, the first annular member defining a first inner hole extending through the first annular member, the first inner hole of the first annular member having a first diameter; a second annular member, the second annular member defining a second inner hole extending through the second annular member, the second inner hole of the second annular member having a second diameter; a valve member, the valve member being clamped between the first annular member and the second annular member, the valve member having a third diameter, and the valve member being impermeable to fluid; wherein the first diameter and the second diameter are both smaller than the third diameter, and wherein the valve member is configured to be destroyed when the fluid pressure difference is greater than or equal to a predetermined opening threshold to open the corresponding fluid channel.

[0011] In one embodiment, the valve member comprises a weakened portion.

[0012] In one embodiment, the valve member has a first side facing the inner cavity of the base pipe and a second side facing the annular space, the first side having a first fluid contact area capable of contacting fluid from the inner cavity of the base pipe, the second side having a second fluid contact area capable of contacting fluid from the annular space, and wherein the first fluid contact area is smaller than the second fluid contact area.

[0013] In one embodiment, each of the one or more fluid valves includes: a first annular member, the first annular member faces the annular space, the first annular member defines a first inner hole extending through the first annular member, the first inner hole of the first annular member has a first diameter; a second annular member, the second annular member defines a second inner hole extending through the second annular member, the second inner hole of the second annular member has a second diameter; a third annular member, the third annular member defines a third inner hole extending through the third annular member, the third inner hole of the third annular member has a third diameter, and the third annular member is clamped in the between the first annular member and the second annular member; a valve member assembled in the third inner hole of the third annular member, the valve member being impermeable to fluid; one or more pins, the one or more pins being arranged in the third annular member at intervals in the circumferential direction and extending into the valve member in the radial direction, thereby fixing the valve member to the third annular member, wherein the first diameter is greater than the third diameter, and wherein the one or more pins are configured to be destroyed when the fluid pressure difference is greater than or equal to a predetermined opening threshold, so that the valve member is removed from the third inner hole of the third annular member, thereby opening the corresponding fluid channel.

[0014] In one embodiment, the second diameter is smaller than the third diameter.

[0015] In one embodiment, at least one of the one or more pins comprises a weakened portion.

[0016] In one embodiment, at least one of the one or more fluid valves further comprises a flow limiting member, which is assembled in the inner cavity of the valve body and is used to limit the fluid flow through the fluid valve.

[0017] In one embodiment, the flow control screen includes two or more fluid valves, and predetermined opening thresholds of at least two of the two or more fluid valves are different from each other.

[0018] According to one aspect of the present invention, there is provided an oil well structure, comprising: a well wall, the well wall defining a wellhead leading to the ground; one or more flow control screens according to the present invention, the one or more flow control screens being arranged in series in the well wall so that the inner cavities of the base pipes of the one or more flow control screens are interconnected to jointly form a transmission channel for transmitting fluid from the downhole to the wellhead; and a sealing body formed by sealing particles, the sealing body filling the annular space between the one or more flow control screens and the well wall.

[0019] According to one aspect of the present invention, there is provided an oil well structure, comprising: a well wall, the well wall defining a wellhead leading to the ground; one or more flow control screens according to the present invention, the one or more flow control screens being arranged in series in the well wall so that the inner cavities of the base pipes of the one or more flow control screens are connected to each other to jointly form a transmission channel for transmitting fluid from the downhole to the wellhead; and a packer arranged between every two adjacent flow control screens, the packer being configured to axially isolate the annular space between the one or more flow control screens and the well wall from each other.

[0020] According to one aspect of the present invention, a method for operating an oil well structure according to the present invention is provided, comprising: applying a first pressure from the wellhead to the transmission channel so that at least one fluid valve opens.

[0021] In one embodiment, the method further comprises: applying a second pressure greater than the first pressure from the wellhead to the transmission channel, so that at least one additional fluid valve opens.

[0022] According to one aspect of the present invention, a method for modifying an oil well structure is provided, the oil well structure comprising a well wall and a screen pipe, the well wall defining a wellhead leading to the ground, the method comprising: perforating the screen pipe of the oil well structure; providing one or more flow control screen pipes according to the present invention; arranging the one or more flow control screen pipes in series in the screen pipe of the oil well structure so that the inner cavities of the base pipes of the one or more flow control screen pipes are connected to each other to jointly form a transmission channel for transmitting fluid from the downhole to the wellhead; and filling the annular space between the screen pipe of the oil well structure and the well wall with sealing particles and filling the annular space between the screen pipe of the oil well structure and the one or more flow control screen pipes.

[0023] The flow control screen according to the present invention can adjust the flow conductivity by pressurizing on the ground through the wellhead. Specifically, at a specific stage of mining, the fluid valve in the flow control screen can be opened by pressurizing on the ground through the wellhead as needed, so that the flow control screen can provide additional flow conductivity and improve the flow conductivity. Compared with the prior art, the flow control screen according to the present invention conveniently and easily adjusts the flow conductivity of the flow control screen.

[0024] More preferably, in the embodiment where the flow control screen has two or more fluid valves, at different stages of exploitation, the fluid valves of the flow control screen can be gradually opened by pressurizing on the ground through the wellhead as needed (for example, several fluid valves are opened first, and then several other fluid valves are opened after a period of time), so as to achieve a step-by-step improvement in the flow conductivity. By adjusting the flow conductivity of the flow control screen in stages and in stages, the daily oil production of the oil well can be ensured during the entire exploitation period and the effective production time of the oil well can be extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1a A perspective view schematically shows a flow control screen for an oil well according to the present invention;

[0026] Figure 1b Schematically shows Figure 1a A cross-sectional view of a flow control screen tube;

[0027] Figure 2 A cross-sectional view schematically shows an embodiment of a flow control screen for an oil well according to the present invention;

[0028] Figure 3a-3b The arrangement of the through holes of the base pipe is schematically shown;

[0029] Figure 4 A cross-sectional view schematically shows another embodiment of a flow control screen for an oil well according to the present invention;

[0030] Figure 5a Schematically shows a perspective exploded view of one embodiment of a fluid valve according to the present invention;

[0031] Figure 5b Schematically shows Figure 5a A cross-sectional view of a fluid valve, wherein the valve member is in a normal state;

[0032] Figure 5c Schematically shows Figure 5a A cross-sectional view of a fluid valve, wherein the valve member is in a damaged state;

[0033] Figure 6a-6b A schematic diagram showing an embodiment of a valve member;

[0034] Figure 7 Schematically shows the force analysis of the valve component according to the present invention;

[0035] Figure 8a Schematically shows a perspective exploded view of one embodiment of a fluid valve according to the present invention;

[0036] Figure 8b Schematically shows Figure 8a A cross-sectional view of a fluid valve, wherein the pin is in a normal state;

[0037] Figure 8c Schematically shows Figure 8a A cross-sectional view of a fluid valve, wherein the pin is in a destroyed state;

[0038] Figure 9a-9b A schematic diagram showing an embodiment of a pin is shown;

[0039] Figure 10a-10b A flow-restricting member is schematically shown;

[0040] Figure 11a-11b An embodiment of an oil well structure including a flow control screen according to the present invention is schematically shown; and

[0041] Figure 12a-12b An embodiment of an oil well structure including a flow control screen according to the present invention is schematically shown. DETAILED DESCRIPTION

[0042] Figure 1a The flow control screen 100 for oil wells according to the present invention is schematically shown in a perspective view. The flow control screen 100 may include a hollow base pipe 110 and a hollow filter pipe 120 .

[0043] Figure 1b Schematically shows Figure 1a A cross-sectional view of the flow control screen. Figure 1b As shown, the base pipe 110 may include a fluid-impermeable wall 112 . The wall 112 of the base pipe 110 may define a lumen C. The base pipe 110 may have one or more through holes 114 formed in the wall 112 . Figure 1b Two through holes 114 are shown. The flow control screen 100 according to the present invention may also include other numbers of through holes 114, such as 1, 3, 4, 5, 10, 50, or 100.

[0044] The filter tube 120 may include a fluid-permeable tube wall 122. The filter tube 120 may be disposed around the outer side of at least a portion of the base pipe 110, so that an annular space 124 is formed between the filter tube 120 and the base pipe 110. The two axial ends of the annular space 124 may be sealed by any suitable sealing means. Since the tube wall 122 of the filter tube 120 is fluid-permeable, the formation fluid may enter the annular space 124 through the tube wall 122 of the filter tube 120, and the sand, gravel, etc. in the formation are filtered by the tube wall 122 of the filter tube 120.

[0045] One or more fluid passages 126 may be defined between the annular space 124 and the lumen C of the base pipe 110 . Figure 1b Two fluid channels 126 are shown in FIG. The flow control screen 100 according to the present invention may also include other numbers of fluid channels 126, such as 1, 3, 4, 5, 10, 50, or 100. Figure 1bIn the figure, the fluid channel 126 is shown by a dotted line, and one end of the fluid channel 126 extends into the annular space 124, and the other end extends into the inner cavity C of the base pipe 110, which means that the fluid channel 126 of the present invention can lead from any position in the annular space 124 to any position in the inner cavity C of the base pipe 110 through any suitable path. The fluid channel 126 can be straight, curved or in any other suitable shape. The function of the fluid channel 126 is to provide a flow path from the annular space 124 to the inner cavity C of the base pipe 110.

[0046] The flow control screen 100 may also include one or more fluid valves 130 . Figure 1b Two fluid valves 130 are shown. The flow control screen 100 according to the present invention may also include other numbers of fluid valves 130, such as 1, 3, 4, 5, 10, 50, or 100.

[0047] Each of the fluid valves 130 may be disposed in a corresponding one of the fluid channels 126. The fluid valves 130 may be disposed at any suitable position of the fluid channels 126. In the present invention, the number of through holes 114 in the wall 112 of the base pipe 110, the number of fluid channels 126, and the number of fluid valves 130 may correspond to each other, so that each fluid valve 130 corresponds to one through hole 114 and one fluid channel 126.

[0048] Each of the fluid valves 130 may have a first side S1 facing the inner cavity C of the base pipe 110 and a second side S2 facing the annular space 124. That is, the first side S1 of the fluid valve 130 is closer to the inner cavity C of the base pipe 110 than the second side S2 of the fluid valve 130, and the second side S2 of the fluid valve 130 is closer to the annular space 124 than the first side S1 of the fluid valve 130. The fluid valve 130 may be closed in an initial state to block the corresponding fluid channel 126, so that the fluid in the annular space 124 cannot enter the inner cavity C of the base pipe 110 via the fluid channel 126.

[0049] Each of the fluid valves 130 may have a respective predetermined opening threshold, and may be configured to open when a fluid pressure difference ΔP between a fluid pressure P1 applied from the inner cavity C of the base pipe 110 to the first side S1 of the fluid valve 130 and a fluid pressure P2 applied from the annular space 124 to the second side S2 of the fluid valve 130 is greater than or equal to the respective predetermined opening threshold, so as to open the corresponding fluid passage 126, so that the fluid in the annular space 124 can flow into the inner cavity C of the base pipe 110 via the corresponding fluid passage 126.

[0050] Each of the fluid valves 130 may also be configured to remain closed when subjected only to the fluid pressure applied from the annular space 124 to the second side S2 of the fluid valve 130, so as to block the corresponding fluid passage 126, so that the fluid in the annular space 124 cannot enter the inner cavity C of the base pipe 110 via the fluid passage 126. In other words, the predetermined opening threshold of each of the fluid valves 130 may be greater than the fluid pressure applied from the annular space 124 to the second side S2 of the fluid valve 130.

[0051] Figure 2 A cross-sectional view of an embodiment of a flow control screen 100 for an oil well according to the present invention is schematically shown. Figure 2 As shown, each of the fluid valves 130 may be disposed in or near a corresponding one of the through holes 114 of the base pipe 110 to block or allow the fluid in the annular space 124 to enter the inner cavity C of the base pipe 110 via the through hole. For example, the fluid valve 130 may be disposed in the through hole 114, may be disposed on a side of the through hole 114 close to the annular space 124, or may be disposed on a side of the through hole 114 close to the inner cavity C of the base pipe 110. For the embodiment in which the fluid valve 130 is disposed in the through hole 114, the fluid passage 126 is defined by the through hole 114 of the base pipe 110. In this case, the fluid in the annular space 124 directly enters the inner cavity C of the base pipe 110 via the through hole 114. Figure 2 , three through holes 114 are shown. The flow control screen 100 according to the present invention may also include other numbers of through holes 114, such as 1, 2, 4, 5, 10, 50, or 100. Figure 2 Three fluid valves 130 are shown. The flow control screen 100 according to the present invention may also include other numbers of fluid valves 130, such as 1, 2, 4, 5, 10, 50, or 100.

[0052] Figure 3a-3b The arrangement of the through holes of the base tube is schematically shown. In one embodiment, Figure 3a As shown, the through holes 114 may be arranged at intervals along the circumferential direction of the base pipe 110. In one embodiment, as shown in FIG. Figure 3b As shown, the through holes 114 may be arranged at intervals along the longitudinal direction of the base pipe 110 .

[0053] Figure 4 A cross-sectional view of another embodiment of a flow control screen for an oil well according to the present invention is schematically shown. Figure 4As shown, the pipe wall 112 of the base pipe 110 may include a first section 116 and an adjacent second section 118. One or more through holes 114 may be formed in the first section 116 at intervals in the circumferential direction. The filter tube 120 may be arranged around the outer side of at least a portion of the second section 118. In this embodiment, the flow control screen 100 may also include a hollow end ring 140. The end ring 140 may be assembled on the outer side of at least a portion of the first section 116 and connected to the filter tube 120. The pipe wall of the end ring 140 may have one or more axial holes 142 and one or more radial holes 144. The one or more axial holes 142 of the end ring 140 may be in fluid communication with the annular space 124. Each of the one or more radial holes 144 of the end ring 140 may fluidly connect a corresponding one of the one or more axial holes 142 of the end ring 140 to a corresponding one of the one or more through holes 114 of the base pipe 110, thereby defining one or more fluid channels 126. In this embodiment, the fluid passage 126 may be defined by the through-hole 114 of the base pipe 110 , the corresponding radial holes 144 , and the corresponding axial holes 142 .

[0054] like Figure 4 As shown, each of the one or more fluid valves 130 may be disposed in a corresponding one of the one or more axial holes 142 of the end ring 140. In this embodiment, the fluid in the annular space 124 may enter the inner cavity C of the base pipe 110 via the axial hole 142, the fluid valve 130, the radial hole 144, and the through hole 114. In other embodiments, each of the one or more fluid valves 130 may be disposed in a corresponding one of the one or more radial holes 144 of the end ring 140, or in a corresponding one of the one or more through holes 114. Alternatively, a portion of the fluid valves 130 may be disposed in the axial hole 142 of the end ring 140, a portion of the fluid valves 130 may be disposed in the radial hole 144 of the end ring 140, and a portion of the fluid valves 130 may be disposed in the through hole 114.

[0055] Figure 5a Schematically shows a perspective exploded view of an embodiment of a fluid valve according to the present invention. Figure 5a As shown, the fluid valve 130 may include a hollow valve body 132, a first annular member 134, a second annular member 136, and a valve member 138. The valve body 132 may define an interior cavity.

[0056] The valve body 132 may be a separate component. The valve body 132 may also be formed as one piece with the hole wall of the portion where the fluid valve 130 is installed. For example, if the fluid valve 130 is installed in the through hole 114 of the base pipe 110, the valve body 132 may be formed as one piece with the hole wall of the through hole 114. For another example, if the fluid valve 130 is installed in the axial hole 142 of the end ring 140, the valve body 132 may be formed as one piece with the hole wall of the axial hole 142.

[0057] Figure 5b Schematically shows Figure 5a 1. A cross-sectional view of a fluid valve of FIG. 130. A first annular member 134 may be connected to a valve body 132. The first annular member 134 may face the annular space 124. That is, when the fluid valve 130 is positioned in the fluid passage 126, the first annular member 134 is closer to the annular space 124 than the second annular member 136 and the valve member 138. The first annular member 134 may define a first inner hole 134H extending through the first annular member 134. The first inner hole 134H of the first annular member 134 may have a first diameter. The second annular member 136 may be connected to the valve body 132. The second annular member 136 may define a second inner hole 136H extending through the second annular member 136. The second inner hole 136H of the second annular member 136 may have a second diameter.

[0058] The valve member 138 may be assembled in the inner cavity of the valve body 132. The valve member 138 may be sandwiched between the first annular member 134 and the second annular member 136. The valve member 138 may have a third diameter. The valve member 138 may be fluid-tight. The first diameter of the first inner hole 134H of the first annular member 134 and the second diameter of the second inner hole 136H of the second annular member 136 may both be smaller than the third diameter of the valve member 138, so that the valve member 138 is sandwiched between the first annular member 134 and the second annular member 136. Moreover, due to the presence of the first inner hole 134H of the first annular member 134 and the second inner hole 136H of the second annular member 136, the first side of the valve member 138 may be subjected to the fluid pressure from the inner cavity C of the base pipe 110, and the opposite second side of the valve member 138 may be subjected to the fluid pressure from the annular space 124.

[0059] The valve member 138 may be configured to remain intact when only subjected to the fluid pressure from the annular space 124 to block the corresponding fluid passage 126, so that the fluid in the annular space 124 cannot enter the inner cavity C of the base pipe 110 via the fluid passage 126. Figure 5b As shown, the valve member 138 is in a normal state, that is, the valve member 138 remains intact.

[0060] The valve member 138 may also be configured to be destroyed when the difference between the fluid pressures received by the first side and the second side is greater than or equal to a predetermined opening threshold, so as to open the corresponding fluid channel 126. In other words, when the fluid pressure received by the first side of the valve member 138 is greater than the fluid pressure received by the second side of the valve member 138 and reaches or exceeds the predetermined opening threshold, the valve member 138 is destroyed. Moreover, when the fluid pressure received by the second side of the valve member 138 is greater than the fluid pressure received by the first side of the valve member 138 and reaches or exceeds the predetermined opening threshold, the valve member 138 is destroyed. Figure 5c As shown, the valve member 138 is in a destroyed state, where a portion of the valve member 138 is removed.

[0061] Therefore, in order to destroy the valve member 138 to open the fluid valve 130, a sufficiently large fluid pressure can be applied from the inner cavity C of the base pipe 110 to the first side of the valve member 138, and the fluid pressure is greater than the fluid pressure applied from the annular space 124 to the second side of the valve member 138 to reach or exceed the predetermined opening threshold.

[0062] In one embodiment, the valve member 130 may include an isolation plate. The isolation plate may be made of any suitable material having appropriate strength and being impermeable to fluid, such as stainless steel, aluminum alloy, carbon fiber material, ceramic material, and polymer material (such as PET, etc.).

[0063] Figure 6a-6b 1 shows a schematic diagram of an embodiment of a valve member 130, wherein the valve member 130 includes a weakened portion 130W, which may be a missing portion of material in the valve member 130. Figure 6a In the illustrated embodiment, the weakened portion 130W may be one or more pre-machined spaced apart recesses, which may be arranged in an annular pattern along the circumferential direction. Figure 6b In the illustrated embodiment, the weakened portion 130W may be a pre-machined annular groove. Additionally, in other embodiments, the weakened portion may be a reduced strength portion in the valve member 130. The reduced strength portion may be one or more regions in the valve member 130 that are formed of a material with lower strength. For example, the reduced strength portion may be made of a material with lower strength than the material of other portions of the valve member 130, and / or one or more regions in the valve member 130 may be treated to reduce its strength to form the reduced strength portion. By providing a weakened portion in the valve member 130, the predetermined opening threshold for destroying the valve member 130 may be reduced, thereby allowing the use of a material with higher strength without causing excessive fluid pressure to be applied when destroying the valve member 130.

[0064] Figure 7 The force analysis of the valve member 130 according to the present invention is schematically shown. Figure 7 As shown, the valve member 130 may have a first side S1 facing the inner cavity C of the base pipe 110 and a second side S2 facing the annular space 124. In one embodiment, the first side S1 of the valve member 130 may have a first fluid contact area that can contact the fluid from the inner cavity C of the base pipe 110. The second side S2 of the valve member 130 may have a second fluid contact area that can contact the fluid from the annular space 124, wherein the first fluid contact area may preferably be smaller than the second fluid contact area. Figure 7 Explain the advantages of this design.

[0065] exist Figure 7 In the embodiment, at the first side S1 of the valve member 130, the diameter of the surface in contact with the fluid is d. At the second side S2 of the valve member 130, the diameter of the surface in contact with the fluid is D. S1 P represents the critical breaking pressure of the valve member 130 on the first side S1. S2 represents the critical breaking pressure of the valve member 130 on the second side S2. In other words, when the pressure on the first side S1 of the valve member 130 is greater than the pressure on the second side S2 and the pressure difference is P S1 Similarly, when the pressure on the second side S2 of the valve member 130 is greater than the pressure on the first side S1 and the pressure difference is P S2 When the valve member 130 is broken, the valve member 130 is broken. The problem of the damage of the valve member 130 can be simplified to the shear problem of the material of the valve member 130. According to the practical shear calculation formula, it can be obtained:

[0066] (1)

[0067] Here, t is the thickness of the valve member 130 , and τ is the shear strength of the material of the valve member 130 .

[0068] Simplifying formula (1) we can obtain:

[0069] (2)

[0070] Similarly, we can know:

[0071] (3)

[0072] According to formula (2) and formula (3), we can get:

[0073] (4)

[0074] It can be seen from equations (2) and (3) that the critical breaking pressure of the valve member 130 is proportional to the shear strength of the valve member 130 , proportional to the thickness of the valve member 130 , and inversely proportional to the diameter of the surface of the valve member 130 in contact with the fluid.

[0075] From formula (4), it can be seen that for the same valve member 130, when D > d, P S2 > P S1 By further generalization, it can be known that, for the same valve component 130, when the fluid contact area on the first side is smaller than the fluid contact area on the second side, the critical breaking pressure on the first side is smaller than the critical breaking pressure on the second side.

[0076] Based on the above analysis, it can be known that if the first fluid contact area on the first side (the side facing the inner cavity C of the base pipe 110) of the valve member 130 is set to be smaller than the second fluid contact area on the second side (the side facing the annular space 124) of the valve member 130, then the critical breaking pressure on the first side (the side facing the inner cavity C of the base pipe 110) of the valve member 130 will be smaller than the critical breaking pressure on the second side (the side facing the annular space 124) of the valve member 130. In this case, applying a small pressure on the first side (the side facing the inner cavity C of the base pipe 110) of the valve member 130 can cause the valve member 130 to be destroyed, thereby opening the valve 130. In this way, the magnitude of the pressure applied from the inner cavity C of the base pipe 110 to the first side of the valve member 130 in order to destroy the valve member 130 can be reduced, thereby reducing the requirements for the pressurizing equipment that applies pressure from the inner cavity C of the base pipe 110.

[0077] Figure 8a Schematically shows a perspective exploded view of an embodiment of a fluid valve according to the present invention. Figure 8a As shown, the fluid valve 230 may include a hollow valve body 232, a first annular member 234, a second annular member 236, a second annular member 238, a valve member 240, and one or more pins 242. The valve body 232 may define an inner cavity. The valve body 232 may be a separate component. The valve body 232 may also be formed as one piece with the hole wall of the portion where the fluid valve 230 is installed. For example, if the fluid valve 230 is installed in the through hole 114 of the base pipe 110, the valve body 232 may be formed as one piece with the hole wall of the through hole 114. For another example, if the fluid valve 230 is installed in the axial hole 142 of the end ring 140, the valve body 232 may be formed as one piece with the hole wall of the axial hole 242.

[0078] Figure 8b Schematically shows Figure 8a 2. A cross-sectional view of a fluid valve of FIG. 230. The first annular member 234 may be connected to the valve body 232. The first annular member 234 may face the annular space 124. That is, when the fluid valve 230 is positioned in the fluid passage 126, the first annular member 234 is closer to the annular space 124 than the second annular member 236, the third annular member 238, and the valve member 240. The first annular member 234 may define a first inner hole 234H extending through the first annular member 234. The first inner hole 234H of the first annular member 234 may have a first diameter.

[0079] The second annular member 236 may be connected to the valve body 132. The second annular member 236 may define a second inner bore 236H extending through the second annular member 236. The second inner bore 236H of the second annular member 236 may have a second diameter.

[0080] The third annular member 238 may be assembled in the inner cavity of the valve body 132. The third annular member 238 may define a third inner hole 238H extending through the third annular member 238. The third inner hole 238H of the third annular member 238 may have a third diameter. The third annular member 238 may be sandwiched between the first annular member 234 and the second annular member 236.

[0081] The valve member 240 may be fitted in the third inner hole 238H of the third annular member 238. The valve member 240 may be fluid-tight.

[0082] One or more pins 242 may be disposed in the third annular member 238 at intervals in the circumferential direction and may extend into the valve member 240 in the radial direction, thereby fixing the valve member 240 to the third annular member 238 .

[0083] The first diameter of the first inner hole 234H of the first annular member 234 and the second diameter of the second inner hole 236H of the second annular member 236 may both be smaller than the outer diameter of the third annular member 238, so that the third annular member 238 is sandwiched between the first annular member 234 and the second annular member 236. In addition, due to the presence of the first inner hole 234H of the first annular member 234 and the second inner hole 236H of the second annular member 236, the first side of the valve member 240 may be subjected to the fluid pressure from the inner cavity C of the base pipe 110, and the opposite second side of the valve member 240 may be subjected to the fluid pressure from the annular space 124.

[0084] The first diameter of the first inner hole 234H of the first annular member 234 may be greater than the third diameter of the third inner hole 238H of the third annular member 238 so that the valve member 240 may be removed from the third inner hole 238H of the third annular member 238 in a direction toward the annular space.

[0085] One or more pins 242 may be configured to remain intact when subjected only to fluid pressure from the annular space 124 to fix the valve member 240 in place, thereby blocking the corresponding fluid passage 126, so that the fluid in the annular space 124 cannot enter the inner cavity C of the base pipe 110 via the fluid passage 126. Figure 8b As shown, the pin 242 is in a normal state, that is, the pin 242 remains intact.

[0086] One or more pins 242 may also be configured to be destroyed when the difference between the fluid pressures received by the first side and the second side of the valve member 240 is greater than or equal to a predetermined opening threshold, so that the valve member 240 is no longer fixed to the third annular member 238, and the valve member 240 can be removed from the third inner hole 238H of the third annular member 238, thereby opening the corresponding fluid channel 126. In other words, when the fluid pressure received by the first side of the valve member 240 is greater than the fluid pressure received by the second side of the valve member 240 and reaches or exceeds the predetermined opening threshold, the one or more pins 242 are destroyed, such as being sheared off. Moreover, when the fluid pressure received by the second side of the valve member 240 is greater than the fluid pressure received by the first side of the valve member 240 and reaches or exceeds the predetermined opening threshold, the one or more pins 242 are destroyed, such as being sheared off. Figure 8c As shown, the pin 242 is in a destroyed state, at which time the valve member 240 is removed from the third inner hole 238H of the third annular member 238.

[0087] Therefore, in order to break one or more pins 242 to open the fluid valve 230, a sufficiently large fluid pressure can be applied from the inner cavity C of the base pipe 110 to the first side of the valve member 240, which is greater than the fluid pressure applied from the annular space 124 to the second side of the valve member 240 to reach or exceed the predetermined opening threshold.

[0088] In one embodiment, the valve member 240 can be made of any suitable material with appropriate strength and impermeable to fluid, such as stainless steel, aluminum alloy, carbon fiber material, ceramic material and polymer material (such as PET, etc.). The pin 242 can be made of any suitable material with appropriate strength.

[0089] In one embodiment, Figure 8b As shown, the second diameter of the second inner hole 236H of the second annular member 236 can be smaller than the third diameter of the third inner hole 238H of the third annular member 238, so that a shoulder 244 is formed between the second annular member 236 and the third annular member 238, and the valve member 240 is positioned against the shoulder 244. Due to the blocking of the valve member 240 by the shoulder 244, the valve member 240 can only move in the direction of the annular space 124 (when one or more pins 242 are broken), but cannot move in the opposite direction.

[0090] Figure 9a-9b Schematic diagram of an embodiment of a pin 242 is shown, wherein the pin 242 includes a weakened portion 242W, which may be a missing portion of material in the pin 242. Figure 9aIn the illustrated embodiment, the weakened portion 242W may be one or more spaced-apart recesses pre-machined on the outer surface of the pin 242, and these recesses may be arranged in an annular pattern along the circumferential direction of the outer surface of the pin 242. Figure 9b In the illustrated embodiment, the weakened portion 242W may be an annular groove pre-machined on the outer surface of the pin 242. Additionally, in other embodiments, the weakened portion may be a reduced strength portion in the pin 242. The reduced strength portion may be one or more regions in the pin 242 that are formed of a material with a lower strength. For example, the reduced strength portion may be made of a material with a lower strength than the material of the rest of the pin 242, and / or one or more regions in the pin 242 may be treated to reduce its strength to form the reduced strength portion. By providing a weakened portion in the pin 242, the predetermined opening threshold for breaking the pin 242 may be reduced, thereby allowing the use of a higher strength material without causing excessive fluid pressure to be applied when breaking the pin 242.

[0091] In one embodiment, the fluid valve 130, 230 may further include a flow limiting member 146, 246, which is assembled in the inner cavity of the valve body 132, 232 to limit the fluid flow through the fluid valve 130, 230. The flow limiting member may include an annular member, and the diameter of the inner hole of the annular member may be smaller than the diameter of the inner hole of other components of the fluid valve 130, 230. Figure 5b In the embodiment, one of the first annular member 134 and the second annular member 136 can serve as a flow-limiting member. Figure 8b In the embodiment of the present invention, one of the second annular member 236 and the third annular member 238 may serve as a flow restricting member. Alternatively, the fluid valve 130, 230 may include a separate flow restricting member. Fig.10a The flow restriction member 146 is schematically shown to be assembled in the inner cavity of the valve body 132, and Fig.10b The flow restriction member 246 assembled in the inner cavity of the valve body 232 is schematically shown.

[0092] In one embodiment, when the flow control screen 100 includes two or more fluid valves, the predetermined opening thresholds of at least two fluid valves may be different from each other. By setting the predetermined opening thresholds of the fluid valves to be different from each other, each fluid valve may be opened at a different pressure. That is, a smaller pressure may be applied first to open the fluid valve with a lower predetermined opening threshold, and then a larger pressure may be applied to open the fluid valve with a higher predetermined opening threshold.

[0093] Figure 11a-11b An embodiment of an oil well structure including a flow control screen according to the present invention is schematically shown. Fig.11a A horizontal well structure is shown, wherein the flow control screen is arranged in the horizontal direction. Fig.11b A vertical well structure is shown, wherein the flow control screen is arranged in a vertical direction. In addition, the oil well structure of the present invention can also be a directional well structure, wherein the flow control screen is arranged in an inclined direction. Figure 11a-11b As shown, the oil well structure 1000 may include a well wall 1010, one or more of the above-mentioned flow control screens 100, and a continuous packer 1020. The well wall 1010 defines a wellhead 1030 leading to the ground. The flow control screens 100 are arranged in series in the well wall 1010, so that the inner cavities of the base pipes of these flow control screens are connected to each other to jointly form a transmission channel 1040 for transmitting fluid from the downhole to the wellhead 1030. The continuous packer 1020 can be formed by sealing particles and fill the annular space between the flow control screen 100 and the well wall 1010. During production, the continuous packer 1020 can hinder the axial flow of high-flow water in the high-permeability section without forming cross-flow.

[0094] Figure 12a-12b An embodiment of an oil well structure including a flow control screen according to the present invention is schematically shown. Fig.12a A horizontal well structure is shown, wherein the flow control screen is arranged in the horizontal direction. Figure 12b A vertical well structure is shown, wherein the flow control screen is arranged in a vertical direction. In addition, the oil well structure of the present invention can also be a directional well structure, wherein the flow control screen is arranged in an inclined direction. As shown in FIG. 12 , the oil well structure 2000 may include a well wall 2010, one or more of the above-mentioned flow control screens 100, and a packer 2020 arranged between every two adjacent flow control screens 100. The well wall 2010 defines a wellhead 2030 leading to the ground. The flow control screen 100 is arranged in series in the well wall 2010, so that the inner cavities of the base pipes of these flow control screens are connected to each other to jointly form a transmission channel 2040 for transmitting fluid from the downhole to the wellhead 2030. The packer 2020 can be configured to axially isolate the annular space between the flow control screen 100 and the well wall 2010 from each other. During production, the packer 2020 can hinder the axial flow of high-flow water in the high-permeability section without forming cross-flow.

[0095] In use Figure 11a-11b or Figure 12a-12bDuring the production process of the oil well structure shown, in the later stage of production, as more and more well sections, or even the entire well section, are flooded to varying degrees, water is needed to carry oil, that is, the flow rate from the formation into the flow control screen needs to be increased. At this time, a certain pressure can be applied from the wellhead to the transmission channels 1040, 2040 using a pressurizing device 200. The pressure applied from the wellhead to the transmission channels 1040, 2040 is applied to the first side S1 of each fluid valve 130, 230 via each through hole 114 and each fluid channel 126 in the base pipe 110 of each flow control screen 100. Each fluid valve 130, 230 is subjected to the same pressure on the first side S1. If the difference between the pressure and the fluid pressure from the annular space 124 (i.e., the pressure minus the fluid pressure from the annular space 124) is greater than or equal to the predetermined opening threshold of at least one fluid valve, the at least one fluid valve is opened, and the remaining fluid valves remain closed. Since at least one fluid valve (which was originally closed) is opened by surface pressurization, an additional fluid path is provided in the flow control screen (from the annular space through the opened fluid valve into the inner cavity of the base pipe), thereby increasing the flow rate from the formation into the flow control screen.

[0096] Next, as the exploitation continues, it is necessary to further increase the flow rate from the formation into the flow control screen. At this time, a higher pressure can be applied from the wellhead to the transmission channels 1040, 2040 using a pressurizing device 200 to open at least one fluid valve with a higher predetermined opening threshold, thereby further increasing the flow rate from the formation into the flow control screen.

[0097] By setting the predetermined opening threshold of the fluid valve in the flow control screen to different values, the fluid valve in the flow control screen can be opened step by step and in batches by applying a pressure increasing from small to large through the wellhead using the pressurizing device 200 as needed. In this way, the flow rate entering the flow control screen from the formation can be increased step by step and in batches to meet the needs of different stages in the later stage of mining.

[0098] The present invention also relates to a method for transforming an existing oil well structure. The oil well structure includes a well wall and a screen pipe, and the well wall defines a wellhead leading to the ground. First, the screen pipe of the existing oil well structure is perforated, that is, a plurality of radial channels are formed, so that the screen pipe loses its flow control ability. Then, one or more flow control screen pipes according to the present invention are arranged in series in the screen pipe of the oil well structure, so that the inner cavities of the base pipes of the one or more flow control screen pipes according to the present invention are connected to each other to jointly form a transmission channel for transmitting fluid from the bottom of the well to the wellhead. Then, sealing particles are used to fill the annular space between the screen pipe of the existing oil well structure and the well wall, and to fill the annular space between the screen pipe of the existing oil well structure and one or more flow control screen pipes according to the present invention.

[0099] Example 1

[0100] There is a new well in an offshore oil field. The oil layer viscosity of the well is 142 centipoise, the formation water viscosity is 0.9 centipoise, the oil-water viscosity ratio is 158, the horizontal section wellbore diameter is 6 inches, and the horizontal section length is 1000 meters. The oil well structure according to the present invention is lowered, including 100 flow control screens according to the present invention, each of which includes three fluid valves, which have predetermined opening thresholds of 5MPa, 12MPa and 17MPa respectively. In this way, the entire oil well structure includes 100 fluid valves with a predetermined opening threshold of 5MPa, 100 fluid valves with a predetermined opening threshold of 12MPa, and 100 fluid valves with a predetermined opening threshold of 17MPa.

[0101] After the well was opened, the daily liquid production was 176 cubic meters / day, the daily oil production was 172 cubic meters / day, the water content was 2.3%, and the production pressure difference was 3MPa. After 20 months of stable production, the water content gradually increased to 80%. After comprehensive analysis, the pump and ground processing equipment also met the conditions for liquid extraction, and it was decided to implement the first ground pressurization, pressurizing to 6MPa, and opening 100 fluid valves with a predetermined opening threshold of 5MPa.

[0102] Then, a submersible electric pump was put into production, with a daily liquid production of 321 cubic meters and a daily oil production of 67 cubic meters, with a water content of 79.1%. The water content decreased slightly at the beginning of the measure, and the production pressure difference was 3.3MPa.

[0103] After 16 months of stable production, the water content of the well rose to 90%. After comprehensive analysis, measures were taken to increase fluid and stabilize production. It was decided to implement the second surface pressurization to 14MPa and open 100 fluid valves with a predetermined opening threshold of 12MPa.

[0104] Then, the pump was replaced and the well was started, with a daily liquid output of 612 cubic meters, a daily oil output of 54 cubic meters, a water content of 91.2%, and a production pressure difference of 3.5 MPa.

[0105] After 12 months of continuous production, the water content rose to 98%. After comprehensive analysis, measures were taken to increase fluid and stabilize production, and it was decided to implement the third surface pressurization to 20MPa and open 100 fluid valves with a predetermined opening threshold of 17MPa.

[0106] Then, the submersible electric pump was started, producing 1,000 cubic meters of liquid and 20 cubic meters of oil per day, with a water content of 98% and a production pressure difference of 3.9 MPa.

[0107] Compared with neighboring wells using conventional technology in the same period, the water content of neighboring wells using conventional technology was as high as about 40% at the initial stage, and the water content quickly rose to about 70% after one month. However, the oil well structure according to the present invention has a long waterless oil production period and a slow water rise. In particular, the liquid supply capacity of the flow control screen can be increased in multiple rounds as needed in the later stage, meeting the different liquid extraction requirements at different stages and ensuring the daily oil production. The cumulative oil production of the oil well structure according to the present invention is 4.47×104 cubic meters more than that of neighboring wells using conventional technology in the same period.

[0108] Example 2

[0109] There is an old well in an oil field, with an 8.5-inch borehole and a horizontal section length of 400 meters. A 5.5-inch screen was lowered in the early stage for simple sand control completion. After 90 days of waterless production, low liquid volume, high water content, and high production pressure difference appeared. The daily liquid production was 80 cubic meters / day, and the water content quickly rose to 96%, so the well was shut down and production stopped.

[0110] Comprehensive analysis shows that the main reason for the well's suspension of production was local water production and blockage of the original screen pipe, requiring water control, sand prevention and oil production increase.

[0111] The original screen is perforated to form multiple radial channels, so that the screen loses its flow control capability. Then, 40 flow control screens according to the present invention are arranged in series in the original screen, so that the inner cavities of the base pipes of the 40 flow control screens are connected to each other to form a transmission channel for transmitting fluid from the downhole to the wellhead. Then, the annular space between the original screen and the well wall and the annular space between the original screen and the 40 flow control screens are filled with sealing particles.

[0112] Each flow control screen includes three fluid valves, each having a predetermined opening threshold of 7 MPa, 10 MPa and 15 MPa. Thus, the modified oil well structure includes 40 fluid valves with a predetermined opening threshold of 7 MPa, 40 fluid valves with a predetermined opening threshold of 10 MPa and 40 fluid valves with a predetermined opening threshold of 15 MPa.

[0113] After the pump was put into production, the well produced 180 cubic meters of liquid per day, 65 cubic meters of oil per day, 63.9% of water content, and 2.8 MPa of production pressure difference. After 15 months of stable production, the water content gradually increased to 81%. After analysis, it was necessary to increase the liquid production, and it was decided to implement the first surface pressurization to 8 MPa, and open 40 fluid valves with a predetermined opening threshold of 7 MPa.

[0114] Then, a submersible electric pump was put into production, with a daily liquid output of 350 cubic meters and daily oil output of 63 cubic meters, a water content of 82%, and a production pressure difference of 3.3 MPa.

[0115] After 12 months of stable production, the water content of the well rose to 90%. After comprehensive analysis, measures were taken to increase fluid and stabilize production. It was decided to implement the second surface pressurization to 12MPa and open 40 fluid valves with a predetermined opening threshold of 10MPa.

[0116] Then, the pump was replaced and the well was started, with a daily liquid production of 630 cubic meters, a daily oil production of 49 cubic meters, a water content of 92.2%, and a production pressure difference of 3.7 MPa.

[0117] After 10 months of stable production, the water content slowly rose to 98%. We took measures to increase the fluid and stabilize production again, and decided to implement the third surface pressurization to 18MPa, opening 40 fluid valves with a predetermined opening threshold of 15MPa.

[0118] The well was put into production, with a daily liquid production of 900 cubic meters and a daily oil production of 25 cubic meters, and a production pressure difference of 4.3 MPa. The cumulative increase in oil production was 3.56×104 cubic meters.

[0119] The present invention provides a flow control screen for an oil well, provides an oil well structure using the flow control screen, provides a method for operating the oil well structure, and provides a method for transforming an existing oil well structure using the flow control screen of the present invention.

[0120] According to the present invention, the liquid supply capacity of the downhole flow control screen can be adjusted by surface pressurization, which has the following advantages: (1) simple structure and low implementation risk; (2) compared with the method of using perforation to improve the flow conductivity of the screen, the present invention can prevent sand, while perforation has the risk of gun jamming and sand production; (3) compared with the method of adding a sliding sleeve to adjust the flow conductivity of the screen, the present invention does not need to take an electric pump and its upper pipe string, nor does it need to lower a special tool pipe string for opening the sliding sleeve. The structure is simple and reliable, and only surface pressurization is required to realize the step-by-step opening of the spare channel, which takes up less manpower, material resources and operation time; (4) strong adaptability, vertical wells, horizontal wells (including directional wells) can be used to adjust the flow conductivity of the flow control screen by the present invention; (5) the flow conductivity of the flow control screen can be adjusted step by step and in batches, which significantly increases the daily oil production of the oil well and prolongs the effective production time of the oil well.

[0121] Although the present invention has been described with reference to (one or more) exemplary embodiments, it will be understood by those skilled in the art that the present invention is not limited to the exact structure and components described herein, and that various modifications, changes and variations may be apparent from the foregoing description without departing from the spirit and scope of the present invention as defined in the appended claims. The present invention is not limited by the illustrated order of steps, as some steps may be performed in a different order and / or simultaneously with other steps. Therefore, the present invention is not limited to the specific (one or more) embodiments disclosed, but will include all embodiments falling within the scope of the appended claims.

Claims

1. A flow control screen for an oil well, comprising: a hollow base pipe, the base pipe comprising a fluid-impermeable wall, the wall of the base pipe defining an inner cavity, the base pipe having one or more through holes formed in the wall; a hollow filter tube, the filter tube comprising a fluid-permeable tube wall, the filter tube being disposed around the outside of at least a portion of the base tube such that an annular space is formed between the filter tube and the base tube, and one or more fluid passages are defined between the annular space and the inner cavity of the base tube; as well as one or more fluid valves, each of the one or more fluid valves being disposed within a corresponding one of the one or more fluid passages, each of the one or more fluid valves having a first side facing the lumen of the base pipe and a second side facing the annular space, wherein the one or more fluid valves are closed in an initial state to block the corresponding fluid passage, and wherein each of the one or more fluid valves has a respective predetermined opening threshold and is configured to open when a fluid pressure difference between a fluid pressure applied from the inner cavity of the base pipe to a first side of the fluid valve and a fluid pressure applied from the annular space to a second side of the fluid valve is greater than or equal to the respective predetermined opening threshold, so as to open the corresponding fluid passage, so that the fluid in the annular space can flow into the inner cavity of the base pipe via the corresponding fluid passage.

2. The flow control screen according to claim 1, wherein: Each of the one or more fluid valves is disposed in or near a corresponding one of the one or more through holes of the base pipe to block or allow fluid to enter the inner cavity of the base pipe through the through hole.

3. The flow control screen according to claim 2, wherein: The one or more through holes are arranged at intervals along the circumferential direction of the base pipe; or The one or more through holes are arranged at intervals along the longitudinal direction of the base pipe.

4. The flow control screen according to claim 1, wherein: The tube wall of the base tube includes a first section and an adjacent second section, the one or more through holes are formed in the first section at intervals along the circumferential direction, and the filter tube is arranged around the outer side of at least a part of the second section; and The flow control screen further comprises a hollow end ring, which is assembled on the outside of at least a portion of the first section and connected to the filter tube, and the tube wall of the end ring has one or more axial holes and one or more radial holes, the one or more axial holes of the end ring are in fluid communication with the annular space, and each of the one or more radial holes of the end ring fluidly connects a corresponding one of the one or more axial holes of the end ring to a corresponding one of the one or more through holes of the base pipe, thereby defining the one or more fluid channels.

5. The flow control screen according to claim 4, wherein: Each of the one or more fluid valves is disposed in a corresponding one of the one or more axial bores of the end ring.

6. The flow control screen according to any one of claims 1 to 5, wherein: Each of the one or more fluid valves comprises: a first annular member, the first annular member facing the annular space, the first annular member defining a first inner hole extending through the first annular member, the first inner hole of the first annular member having a first diameter; a second annular member, the second annular member defining a second inner bore extending therethrough, the second inner bore of the second annular member having a second diameter; a valve member sandwiched between the first annular member and the second annular member, the valve member having a third diameter, the valve member being fluid-tight; wherein the first diameter and the second diameter are both smaller than the third diameter, and Wherein, the valve member is configured to be destroyed when the fluid pressure difference is greater than or equal to a predetermined opening threshold value, so as to open the corresponding fluid channel.

7. The flow control screen according to claim 6, wherein: The valve member includes a weakened portion.

8. The flow control screen according to claim 6, wherein: The valve member has a first side facing the inner cavity of the base pipe and a second side facing the annular space, the first side having a first fluid contact area capable of contacting fluid from the inner cavity of the base pipe, the second side having a second fluid contact area capable of contacting fluid from the annular space, and wherein the first fluid contact area is smaller than the second fluid contact area.

9. The flow control screen according to claim 7, wherein: The valve member has a first side facing the inner cavity of the base pipe and a second side facing the annular space, the first side having a first fluid contact area capable of contacting fluid from the inner cavity of the base pipe, the second side having a second fluid contact area capable of contacting fluid from the annular space, and wherein the first fluid contact area is smaller than the second fluid contact area.

10. The flow control screen according to any one of claims 1 to 5, wherein: Each of the one or more fluid valves comprises: a first annular member, the first annular member facing the annular space, the first annular member defining a first inner hole extending through the first annular member, the first inner hole of the first annular member having a first diameter; a second annular member, the second annular member defining a second inner bore extending therethrough, the second inner bore of the second annular member having a second diameter; a third annular member, the third annular member defining a third inner bore extending therethrough, the third inner bore of the third annular member having a third diameter, the third annular member being sandwiched between the first annular member and the second annular member; a valve member assembled in the third inner hole of the third annular member, the valve member being impermeable to fluid; one or more pins, the one or more pins being arranged in the third annular member at intervals in the circumferential direction and extending into the valve member in the radial direction, thereby fixing the valve member to the third annular member, wherein the first diameter is greater than the third diameter, and The one or more pins are configured to be destroyed when the fluid pressure difference is greater than or equal to a predetermined opening threshold, so that the valve member is removed from the third inner hole of the third annular member, thereby opening the corresponding fluid channel.

11. The flow control screen according to claim 10, wherein: The second diameter is smaller than the third diameter.

12. The flow control screen according to claim 10, wherein: At least one of the one or more pins includes a weakened portion.

13. The flow control screen according to claim 1, wherein: At least one of the one or more fluid valves further includes a flow limiting member, which is assembled in the inner cavity of the valve body of the at least one fluid valve and is used to limit the fluid flow through the at least one fluid valve.

14. The flow control screen of claim 1, wherein: The flow control screen includes two or more fluid valves, and predetermined opening thresholds of at least two of the two or more fluid valves are different from each other.

15. An oil well structure, comprising: a well wall, the well wall defining a well head leading to the surface; One or more flow control screens according to any one of claims 1 to 14, the one or more flow control screens being arranged in series in the wellbore wall so that the inner cavities of the base pipes of the one or more flow control screens are connected to each other to jointly form a transmission channel for transmitting fluid from the downhole to the wellhead; as well as A packer is formed by packing particles, and the packer fills the annular space between the one or more flow control screens and the wellbore wall.

16. An oil well structure, comprising: a well wall, the well wall defining a well head leading to the surface; One or more flow control screens according to any one of claims 1 to 14, the one or more flow control screens being arranged in series in the wellbore wall so that the inner cavities of the base pipes of the one or more flow control screens are connected to each other to jointly form a transmission channel for transmitting fluid from the downhole to the wellhead; as well as A packer is disposed between every two adjacent flow control screens, and the packer is configured to axially isolate the annular space between the one or more flow control screens and the well wall from each other.

17. A method for operating an oil well structure according to claim 15 or 16, comprising: A first pressure is applied from the wellhead to the transmission channel, causing at least one fluid valve to open.

18. The method according to claim 17, wherein: The method further comprises: A second pressure greater than the first pressure is applied from the wellhead to the transmission channel, causing at least one additional fluid valve to open.

19. A method for modifying an oil well structure, the oil well structure comprising a well wall and a screen, the well wall defining a wellhead leading to the ground, the method comprising: perforating the screen of the oil well structure; Providing one or more flow control screens according to any one of claims 1 to 14; The one or more flow control screens are arranged in series in the screen of the oil well structure, so that the inner cavities of the base pipes of the one or more flow control screens are connected to each other to jointly form a transmission channel for transmitting fluid from the downhole to the wellhead; as well as The sealing particles are used to fill the annular space between the screen of the oil well structure and the well wall and to fill the annular space between the screen of the oil well structure and the one or more flow control screens.

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