CN216142738U

CN216142738U - Flow control screen for oil well and oil well structure

Info

Publication number: CN216142738U
Application number: CN202120277588.0U
Authority: CN
Inventors: 裴柏林; 吴建昌; 刘穆华; 聂建飞
Original assignee: Anton Bailin Oilfield Technology Beijing Co ltd
Current assignee: Anton Bailin Oilfield Technology Beijing Co ltd
Priority date: 2021-02-01
Filing date: 2021-02-01
Publication date: 2022-03-29
Anticipated expiration: 2031-02-01

Abstract

The utility model relates to a flow control screen for an oil well having adjustable flow conductivity. The flow control screen of the present invention includes one or more fluid valves, each having a respective predetermined opening threshold and configured to open a corresponding fluid passageway when a fluid pressure differential between a fluid pressure on a first side of the fluid valve and a fluid pressure on a second side of the fluid valve is greater than or equal to the respective predetermined opening threshold. The utility model also relates to an oil well structure with the flow control screen.

Description

Flow control screen for oil well and oil well structure

Technical Field

The utility model relates to a flow control screen for an oil well having adjustable flow conductivity. The utility model also relates to an oil well structure with the flow control screen.

Background

In the development of oil fields, due to the heterogeneity of the oil fields and the difference of oil-water viscosity, the development degree of cracks is different, and the permeability of each section of the stratum is also greatly different. After a period of time in oil field production, water will be discharged locally, and 100% water is discharged locally. For example, a horizontal section of a well in an oil field is 800 m long, 80 m is a high-permeability section, the other sections are low-permeability sections, the underground viscosity of crude oil is 100 centipoise, the water viscosity is 1 centipoise, and the oil-water viscosity ratio is 100. Once the high-permeability section produces water, the water content of the produced liquid is as high as 90%, the oil yield is reduced sharply after water production, for example, the daily produced oil is reduced from 35 square/day to less than 7 square/day when a well is opened, and great loss is caused to an oil field, so that technical measures for reducing water and increasing oil are urgently needed for oil field development. The most effective measure for increasing oil and water content is sectional flow control technology. Common segmented flow control techniques 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, a separate packer or a continuous packer is utilized to block the axial flow of high-flow water in the high-permeability section, and no cross flow is formed. On the other hand, the water flow into the flow control screen pipe along the radial direction is limited by the flow control nozzle of the flow control screen pipe, so that the water flow into the shaft is controlled, and the liquid production of the wellhead is unchanged. Therefore, the production pressure difference can be increased, so that the oil yield of the oil production section is increased, and the effects of water reduction and oil increase are achieved.

The current segmented flow control technology has the following problems to be solved. In the initial stage of production, the purpose of controlling water and increasing oil can be achieved by adopting the flow-limiting packer under the condition that the proportion of the water outlet section in the whole well section is small (for example, only 10 percent of the whole well section). In later stages of production, with more and more well sections, and even the entire well section, flooded to different degrees, it is necessary to bring oil by water, i.e., to increase the flow from the formation into each flow control screen. However, because each flow control screen is provided with a flow limiting mechanism, the fluid production of the formation corresponding to each flow control screen cannot be increased, and sufficient oil cannot be brought out through water. At the moment, the flow-limiting valve on the flow-controlling sieve tube needs to be adjusted to be large, otherwise, the pressure on the flow-limiting valve is too large, the pressure on the flow-limiting valve is too small, the flow rate of the flow-limiting valve on the stratum is too low, and the requirement of increasing the oil content of the extract in the later production period of the oil well cannot be met. In addition, the flow restriction valve needs to be adjusted up in stages. For example, when the water content rises to a certain level (for example, 50% water content), the flow-limiting valve needs to be adjusted by 1 time; when the water content rises further (such as 98 percent of the water content), the flow limiting valve needs to be adjusted 1 time larger. However, it is a difficult problem to achieve a gradual opening of the constrictor valve in a few kilometers of the well. At present, the common method is to install a sliding sleeve in a pipe column, then use a special tool for opening the sliding sleeve to go into the well from the well mouth, go into the position of the sliding sleeve with thousands of meters underground, and push the sliding sleeve open, thereby adjusting the flow guiding capacity of the flow control screen pipe. However, this method requires the production of electric pumps and production strings above them, which is expensive and time-consuming, and also requires the connection of strings of thousands of meters for opening the sliding sleeves, which consumes a lot of manpower and material resources and delays the production of oil wells.

Accordingly, there is a need in the art for a convenient and easy to implement staged, progressive adjustment of the flow control screen conductivity to ensure the daily production of the well and extend the effective production time of the well throughout production.

SUMMERY OF THE UTILITY MODEL

According to one aspect of the present invention, there is provided a flow control screen for an oil well, comprising: a hollow base pipe comprising a fluid-tight pipe wall defining an internal cavity, the base pipe having one or more through-holes formed in the pipe wall; a hollow filter tube comprising a fluid permeable tube wall, the filter tube disposed around an 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, one or more fluid passages being defined between the annular space and an inner cavity of the base tube; and one or more fluid valves, each of the one or more fluid valves disposed within a corresponding one of the one or more fluid channels, each of the one or more fluid valves having a first side facing an 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 channels, 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 differential between a fluid pressure applied to a first side of the fluid valve from an internal cavity of the base pipe and a fluid pressure applied to a second side of the fluid valve from the annular space is greater than or equal to the respective predetermined opening threshold, to open the corresponding fluid passage so that fluid in the annular space can flow into the internal cavity of the base pipe via the corresponding fluid passage.

In one embodiment, each of the one or more fluid valves is disposed in or adjacent a corresponding one of the one or more through-holes of the base pipe to block or allow fluid to enter the internal cavity of the base pipe via the through-hole.

In one embodiment, the one or more through holes are provided at intervals in a circumferential direction of the base pipe, or the one or more through holes are provided at intervals in a longitudinal direction of the base pipe.

In one embodiment, the base pipe wall comprises a first section in which the one or more through holes are formed at intervals in the circumferential direction and an adjacent second section, the filter pipe being disposed around the outside of at least a portion of the second section; and wherein the flow control screen further comprises a hollow end ring fitted outside at least a portion of the first section and connected to the filter tube, a tube wall of the end ring having one or more axial bores in fluid communication with the annular space and one or more radial bores, each of the one or more radial bores of the end ring fluidly connecting a corresponding one of the one or more axial bores of the end ring to a corresponding one of the one or more through-bores of the base pipe, thereby defining the one or more fluid passages.

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.

In one embodiment, each of the one or more fluid valves includes: a first annular member facing the annular space, the first annular member defining a first bore extending through the first annular member, the first bore of the first annular member having a first diameter; a second annular member defining a second bore extending therethrough, the second bore of the second annular member having a second diameter; a valve member sandwiched between the first and second annular members, the valve member having a third diameter, the valve member being fluid-tight; wherein the first diameter and the second diameter are both less than the third diameter, and wherein the valve member is configured to be broken to open the corresponding fluid passage when the fluid pressure differential is greater than or equal to a predetermined opening threshold.

In one embodiment, the valve member includes a weakened portion.

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 contactable with fluid from the inner cavity of the base pipe, the second side having a second fluid contact area contactable with fluid from the annular space, and wherein the first fluid contact area is smaller than the second fluid contact area.

In one embodiment, each of the one or more fluid valves includes: a first annular member facing the annular space, the first annular member defining a first bore extending through the first annular member, the first bore of the first annular member having a first diameter; a second annular member defining a second bore extending therethrough, the second bore of the second annular member having a second diameter; a third annular member defining a third bore extending therethrough, the third bore of the third annular member having a third diameter, the third annular member being sandwiched between the first and second annular members; a valve member fitted in a third bore of the third annular member, the valve member being fluid-tight; one or more pins circumferentially spaced in the third annular member and extending in a radial direction into the valve member to secure 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 broken when the fluid pressure differential is greater than or equal to a predetermined opening threshold such that the valve member is removed from a third bore of the third annular member to open a corresponding fluid passage.

In one embodiment, the second diameter is less than the third diameter.

In one embodiment, at least one of the one or more pins includes a weakened portion.

In one embodiment, at least one of the one or more fluid valves further comprises a flow restricting member fitted within an internal cavity of the valve body of the at least one fluid valve for restricting fluid flow through the at least one fluid valve.

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

According to an aspect of the present invention, there is provided an oil well structure comprising: a well wall defining a wellhead open to the surface; one or more flow control screens according to the present invention, the one or more flow control screens being arranged in series within the wellbore wall such that the inner cavities of the base pipes of the one or more flow control screens communicate with each other to collectively form a transfer passage for transferring fluid from downhole to wellhead; and an packer formed of packing particles, the packer filling an annular space between the one or more flow control screens and the wellbore wall.

According to an aspect of the present invention, there is provided an oil well structure comprising: a well wall defining a wellhead open to the surface; one or more flow control screens according to the present invention, the one or more flow control screens being arranged in series within the wellbore wall such that the inner cavities of the base pipes of the one or more flow control screens communicate with each other to collectively form a transfer passage for transferring fluid from downhole to wellhead; and a packer disposed between each two adjacent flow control screens, the packer configured to axially seal an annular space between the one or more flow control screens and the borehole wall from each other.

The flow control screen according to the present invention may be adjusted in flow conductivity by pressurizing the screen at the surface via the wellhead. Specifically, at certain stages of production, the fluid valves in the flow control screens may be opened as needed by pressurizing at the surface via the wellhead, enabling the flow control screens to provide additional flow conductivity, resulting in increased flow conductivity. Compared with the prior art, the flow control sieve tube conveniently and easily realizes the adjustment of the flow guide capability of the flow control sieve tube.

More preferably, in embodiments where the flow control screen has two or more fluid valves, the progressive increase in flow conductivity can be achieved by progressively opening the fluid valves of the flow control screen (e.g., opening a number of the fluid valves first and then another number of the fluid valves each time) as needed at different stages of production by pressurizing the well head at the surface. By adjusting the flow conductivity of the flow control screen stage by stage and stage by stage, the daily oil production of the oil well can be ensured in the whole production period, and the effective production time of the oil well can be prolonged.

Drawings

FIG. 1a schematically shows a perspective view of a flow control screen for an oil well according to the present invention;

FIG. 1b schematically illustrates a cross-sectional view of the flow control screen of FIG. 1 a;

FIG. 2 schematically depicts a cross-sectional view of one embodiment of a flow control screen for an oil well according to the present invention;

3a-3b schematically show the arrangement of the through-holes of the base pipe;

FIG. 4 schematically illustrates a cross-sectional view of another embodiment of a flow control screen for an oil well according to the present invention;

FIG. 5a schematically illustrates a perspective exploded view of one embodiment of a fluid valve according to the present disclosure;

FIG. 5b schematically illustrates a cross-sectional view of the fluid valve of FIG. 5a, with the valve member in a normal state;

FIG. 5c schematically illustrates a cross-sectional view of the fluid valve of FIG. 5a, wherein the valve member is in a broken condition;

6a-6b illustrate schematic views of embodiments of valve members;

FIG. 7 schematically illustrates a force analysis of a valve member according to the present invention;

FIG. 8a schematically illustrates a perspective exploded view of one embodiment of a fluid valve according to the present disclosure;

FIG. 8b schematically illustrates a cross-sectional view of the fluid valve of FIG. 8a, with the pin in a normal state;

FIG. 8c schematically illustrates a cross-sectional view of the fluid valve of FIG. 8a, wherein the pin is in a broken condition;

9a-9b show schematic views of embodiments of pins;

10a-10b schematically illustrate a flow-limiting member;

11a-11b schematically illustrate one embodiment of a well structure including a flow control screen according to the present invention; and is

Figures 12a-12b schematically illustrate one embodiment of a well structure including a flow control screen according to the present invention.

Detailed Description

FIG. 1a schematically shows a perspective view of a flow control screen for an oil well according to the present invention. The flow control screen 100 may include a hollow base pipe 110 and a hollow filtrate pipe 120.

FIG. 1b schematically illustrates a cross-sectional view of the flow control screen of FIG. 1 a. As shown in FIG. 1b, base pipe 110 may include a fluid-tight pipe wall 112. The wall 112 of the base pipe 110 may define an inner cavity C. Base pipe 110 may have one or more through holes 114 formed in the pipe wall 112. Two through holes 114 are shown in fig. 1 b. Flow control screens 100 according to the present invention may also include other numbers of through-holes 114, such as 1, 3, 4, 5, 10, 50, 100.

The filter tube 120 may include a fluid permeable tube wall 122. The filter tube 120 can be disposed around the outside of at least a portion of the base pipe 110 such 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. Because the wall 122 of the filter tube 120 is permeable to fluids, formation fluids may enter the annulus 124 via the wall 122 of the filter tube 120, while sand, gravel, etc. in the formation is filtered by the wall 122 of the filter tube 120.

One or more fluid passages 126 may be defined between the annular space 124 and the inner cavity C of the base pipe 110. Two fluid channels 126 are shown in FIG. 1 b. Flow control screens 100 according to the present invention may also include other numbers of fluid passages 126, such as 1, 3, 4, 5, 10, 50, 100. In fig. 1b, fluid passage 126 is shown in phantom and extends into annular space 124 at one end and into the inner chamber C of base pipe 110 at the other end, which means that fluid passage 126 of the present invention can be routed from any location in annular space 124 to any location in inner chamber C of base pipe 110 via any suitable path. The fluid channel 126 may be straight, curved, or any other suitable shape. The purpose of fluid passage 126 is to provide a flow path from annular space 124 to the inner cavity C of base pipe 110.

The flow control screen 100 may also include one or more fluid valves 130. Two fluid valves 130 are shown in fig. 1 b. 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, 100.

Each of the fluid valves 130 may be disposed in a corresponding one of the fluid passages 126. Fluid valve 130 may be disposed at any suitable location of fluid passage 126. In the present invention, the number of through-holes 114 in the wall 112 of base pipe 110, the number of fluid passages 126, and the number of fluid valves 130 may correspond to one another such that each fluid valve 130 corresponds to one through-hole 114 and one fluid passage 126.

Each of the fluid valves 130 may have a first side S facing an inner cavity C of the base pipe 110₁And a second side S facing the annular space 124₂. That is, compared to the second side S of the fluid valve 130₂First side S of fluid valve 130₁Closer to the inner cavity C of the base pipe 110 than the first side S of the fluid valve 130₁Second side S of fluid valve 130₂Closer to the annular space 124. Fluid valves 130 may be closed in an initial state to block corresponding fluid passages 126 such that fluid in annular space 124 cannot enter inner cavity C of base pipe 110 via fluid passages 126.

Each of the fluid valves 130 may have a respective predetermined opening threshold and may be configured to be applied to a first side S of the fluid valve 130 from an inner cavity C of the base pipe 110₁Fluid pressure P of₁And a second side S applied to the fluid valve 130 from the annular space 124₂Fluid pressure P of₂Opens to open the corresponding fluid passage 126 when the fluid pressure differential ap is greater than or equal to the respective predetermined opening threshold, such that fluid in the annular space 124 can flow into the inner cavity C of the base pipe 110 via the corresponding fluid passage 126.

Each of the fluid valves 130 may also be configured to be applied only to the second side S of the fluid valve 130 from the annular space 124₂Remains closed to block the corresponding fluid passage 126 such that 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 second side S applied to the fluid valve 130 from the annular space 124₂The fluid pressure of (a).

FIG. 2 schematically illustrates a cross-sectional view of one embodiment of a flow control screen 100 for an oil well according to the present invention. As shown in fig. 2, 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 fluid in the annular space 124 from entering the inner cavity C of the base pipe 110 therethrough. For example, fluid valve 130 may be disposed in throughbore 114, may be disposed on a side of throughbore 114 proximate annular space 124, or may be disposed on a side of throughbore 114 proximate inner bore C of base pipe 110. For embodiments in which fluid valve 130 is disposed in throughbore 114, fluid passage 126 is defined by throughbore 114 of base pipe 110. In this case, fluid in annulus 124 enters bore C of base pipe 110 directly through throughbore 114. Three through holes 114 are shown in fig. 2. Flow control screens 100 according to the present invention may also include other numbers of through-holes 114, such as 1, 2, 4, 5, 10, 50, 100. Three fluid valves 130 are shown in fig. 2. 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, 100.

Fig. 3a-3b schematically show the arrangement of the through-holes of the base pipe. In one embodiment, as shown in FIG. 3a, the through holes 114 may be arranged at intervals in the circumferential direction of the base pipe 110. In one embodiment, as shown in FIG. 3b, the through holes 114 may be disposed at intervals along the longitudinal direction of the base pipe 110.

FIG. 4 schematically illustrates a cross-sectional view of another embodiment of a flow control screen for an oil well according to the present invention. As shown in FIG. 4, the tubular 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 tubes 120 may be disposed around the outside 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. Endrings 140 may be fitted over at least a portion of first section 116 and connected to filter tubes 120. The tube wall of the endring 140 can have one or more axial holes 142 and one or more radial holes 144. One or more axial bores 142 of the endrings 140 may be in fluid communication with the annular space 124. Each of the one or more radial bores 144 of endrings 140 can fluidly connect a corresponding one of the one or more axial bores 142 of endrings 140 to a corresponding one of the one or more throughbores 114 of base pipe 110, thereby defining one or more fluid passages 126. In this embodiment, fluid passage 126 may be defined by a throughbore 114 of base pipe 110, a corresponding radial bore 144, and a corresponding axial bore 142.

As shown in fig. 4, each of the one or more fluid valves 130 may be disposed in a corresponding one of the one or more axial bores 142 of the endring 140. In this embodiment, fluid in annulus 124 may enter inner bore C of base pipe 110 via axial bore 142, fluid valve 130, radial bore 144, and throughbores 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 bores 144 of the endring 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 bore 142 of the endring 140, a portion of the fluid valves 130 may be disposed in the radial bore 144 of the endring 140, and a portion of the fluid valves 130 may be disposed in the through-holes 114.

FIG. 5a schematically illustrates a perspective exploded view of one embodiment of a fluid valve according to the present disclosure. As shown in fig. 5a, 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 internal cavity.

The valve body 132 may be a separate component. The valve body 132 may be formed integrally with the wall of the bore where the fluid valve 130 is mounted. For example, if the fluid valve 130 is installed in the through-bore 114 of the base pipe 110, the valve body 132 may be formed integrally with the bore wall of the through-bore 114. For another example, if the fluid valve 130 is installed in the axial bore 142 of the end ring 140, the valve body 132 may be formed integrally with a bore wall of the axial bore 142.

FIG. 5b schematically illustrates a cross-sectional view of the fluid valve of FIG. 5 a. The first annular member 134 may be connected to the valve body 132. The first annular member 134 may face the annular space 124. That is, the first annular member 134 is closer to the annular space 124 than the second annular member 136 and the valve member 138 when the fluid valve 130 is positioned in the fluid passage 126. The first annular member 134 may define a first bore 134H extending through the first annular member 134. The first bore 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 bore 136H extending through the second annular member 136. The second bore 136H of the second annular member 136 may have a second diameter.

The valve member 138 may fit within the interior cavity of the valve body 132. The valve member 138 may be sandwiched between the first and second

annular members

134, 136. The valve member 138 may have a third diameter. The valve member 138 may be fluid-tight. The first diameter of the first bore 134H of the first annular member 134 and the second diameter of the second bore 136H of the second annular member 136 may each be less than the third diameter of the valve member 138 such that the valve member 138 is sandwiched between the first and second

annular members

134, 136. Also, due to the presence of the first bore 134H of the first annular member 134 and the second bore 136H of the second annular member 136, a first side of the valve member 138 may be subject to fluid pressure from the inner cavity C of the base pipe 110, and an opposite second side of the valve member 138 may be subject to fluid pressure from the annular space 124.

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

The valve member 138 may also be configured to be broken to open the corresponding fluid passage 126 when a difference between the fluid pressures experienced by the first and second sides is greater than or equal to a predetermined opening threshold. In other words, the valve member 138 is broken when the fluid pressure experienced by the first side of the valve member 138 is greater than the fluid pressure experienced by the second side of the valve member 138 by or above a predetermined opening threshold. Also, the valve member 138 is broken when the second side of the valve member 138 is subjected to a fluid pressure that is greater than the fluid pressure that is subjected to the first side of the valve member 138 by at or above a predetermined opening threshold. As shown in fig. 5c, the valve member 138 is in a broken state, at which time a portion of the valve member 138 is removed.

Thus, to break the valve member 138 to cause the fluid valve 130 to open, a sufficient fluid pressure may be applied from the inner cavity C of the base pipe 110 to a first side of the valve member 138 that is greater than the fluid pressure applied from the annular space 124 to a second side of the valve member 138 to reach or exceed a predetermined opening threshold.

In one embodiment, the valve member 130 may comprise an isolation plate. The separator plate may be made of any suitable material having suitable strength and being fluid-tight, such as stainless steel, aluminum alloys, carbon fiber materials, ceramic materials, and polymeric materials (e.g., PET, etc.).

Fig. 6a-6b show schematic views of an embodiment of the valve member 130, wherein the valve member 130 comprises a weakened portion 130W, which may be a material absence in the valve member 130. In the embodiment shown in fig. 6a, the weakened portion 130W may be one or more spaced apart recesses that are pre-machined and may be arranged in a circumferential pattern. In the embodiment shown in fig. 6b, 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 lower strength material. For example, the reduced strength portion may be made of a material having a 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 be reduced in strength to form the reduced strength portion. By providing a weakened portion in the valve member 130, the predetermined opening threshold for breaking the valve member 130 may be reduced, thereby allowing the use of stronger materials without causing excessive fluid pressure to be applied when breaking the valve member 130.

Fig. 7 schematically illustrates a force analysis of the valve member 130 according to the present invention. As shown in FIG. 7, the valve member 130 may have a first side S facing the inner cavity C of the base pipe 110₁And a second side S facing the annular space 124₂. In one embodiment, the first side S of the valve member 130₁May have a first fluid capable of contacting fluid from the interior chamber C of base pipe 110The contact area. Second side S of valve member 130₂May have a second fluid contact area capable of contacting fluid from the annular space 124, wherein the first fluid contact area may preferably be smaller than the second fluid contact area. The advantages of this design are explained below with reference to fig. 7.

In fig. 7, on a first side S of the valve member 130₁The diameter of the surface in contact with the fluid is d. On a second side S of the valve member 130₂The diameter of the surface in contact with the fluid is D. P_S1Showing the valve member 130 on the first side S₁Upper critical failure pressure. P_S2Indicating that the valve member 130 is on the second side S₂Upper critical failure pressure. In other words, when the valve member 130 is on the first side S₁Is subjected to a greater pressure than on the second side S₂Upper pressure and pressure difference P_S1The valve member 130 is broken. Similarly, when the valve member 130 is on the second side S₂Is subjected to a greater pressure than on the first side S₁Upper pressure and pressure difference P_S2The valve member 130 is broken. The failure problem of the valve member 130 can be reduced to a shearing problem of the material of the valve member 130. The following can be obtained according to a practical shearing calculation formula:

（1）

where t is the thickness of the valve member 130 and τ is the shear strength of the material of the valve member 130.

The formula (1) is simplified to obtain:

（2）

the same principle can be known:

（3）

according to the formulas (2) and (3), it is possible to obtain:

（4）

as can be seen from equations (2) and (3), the critical failure 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 fluid-contacting surface of the valve member 130.

From equation (4), when D is the same for the same valve member 130>d is, P_S2 > P_S1. By way of further generalization, for the same valve member 130, when the fluid contact area on the first side is less than the fluid contact area on the second side, the critical failure pressure on the first side is less than the critical failure pressure on the second side.

Based on the above analysis, it can be seen that if the first fluid contact area on the first side of the valve member 130 (the side facing the inner cavity C of the base pipe 110) is set smaller than the second fluid contact area on the second side of the valve member 130 (the side facing the annular space 124), the critical failure pressure on the first side of the valve member 130 (the side facing the inner cavity C of the base pipe 110) will be made smaller than the critical failure pressure on the second side of the valve member 130 (the side facing the annular space 124). In this case, a small pressure applied to the first side of the valve member 130 (the side facing the inner cavity C of the base pipe 110) will cause the valve member 130 to break, thereby opening the valve 130. This reduces the amount of pressure applied from the interior chamber C of the base pipe 110 to the first side of the valve member 130 in order to break the valve member 130, thereby reducing the requirement for a pressurizing device to apply pressure from the interior chamber C of the base pipe 110.

FIG. 8a schematically illustrates a perspective exploded view of one embodiment of a fluid valve according to the present disclosure. As shown in fig. 8a, 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 internal cavity. The valve body 232 may be a separate component. The valve body 232 may also be integrally formed with the wall of the bore where the fluid valve 230 is mounted. For example, if the fluid valve 230 is installed in the through-bore 114 of the base pipe 110, the valve body 232 may be formed integrally with the bore wall of the through-bore 114. For another example, if the fluid valve 230 is installed in the axial bore 142 of the end ring 140, the valve body 232 may be formed integrally with the bore wall of the axial bore 242.

FIG. 8b schematically illustrates a cross-sectional view of the fluid valve of FIG. 8 a. 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 and third

annular members

236, 238 and the valve member 240. The first annular member 234 may define a first bore 234H extending through the first annular member 234. The first inner bore 234H of the first annular member 234 may have a first diameter.

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

The third annular member 238 may fit within the interior cavity of the valve body 132. The third annular member 238 may define a third bore 238H extending through the third annular member 238. The third bore 238H of the third annular member 238 may have a third diameter. The third annular member 238 may be sandwiched between the first and second

annular members

234, 236.

The valve member 240 may be fitted in the third bore 238H of the third annular member 238. The valve member 240 may be fluid-tight.

One or more pins 242 may be circumferentially spaced in the third annular member 238 and may extend in a radial direction into the valve member 240, thereby securing the valve member 240 to the third annular member 238.

The first diameter of the first bore 234H of the first annular member 234 and the second diameter of the second bore 236H of the second annular member 236 may each be less than the outer diameter of the third annular member 238 such that the third annular member 238 is sandwiched between the first and second

annular members

234, 236. Moreover, due to the presence of the first bore 234H of the first annular member 234 and the second bore 236H of the second annular member 236, a first side of the valve member 240 may be subject to fluid pressure from the inner cavity C of the base pipe 110, and an opposite second side of the valve member 240 may be subject to fluid pressure from the annular space 124.

The first diameter of the first bore 234H of the first annular member 234 may be greater than the third diameter of the third bore 238H of the third annular member 238 such that the valve member 240 may be removed from the third bore 238H of the third annular member 238 in a direction toward the annular space.

One or more pins 242 may be configured to remain intact when subjected to fluid pressure only from annulus 124 to secure valve member 240 in place, thereby blocking the corresponding fluid passage 126 such that fluid in annulus 124 cannot enter the inner cavity C of base pipe 110 via fluid passage 126. As shown in fig. 8b, the pin 242 is in a normal state, i.e., the pin 242 remains intact.

The one or more pins 242 may also be configured to be broken when the difference between the fluid pressures experienced by the first and second sides of the valve member 240 is greater than or equal to a predetermined opening threshold, such that the valve member 240 is no longer secured to the third annular member 238, and thus the valve member 240 may be removed from the third bore 238H of the third annular member 238, thereby opening the corresponding fluid passage 126. In other words, when the fluid pressure experienced by the first side of the valve member 240 is greater than the fluid pressure experienced by the second side of the valve member 240 at or above a predetermined opening threshold, the one or more pins 242 are broken, e.g., sheared off. Further, when the fluid pressure experienced by the second side of the valve member 240 is greater than the fluid pressure experienced by the first side of the valve member 240 at or above a predetermined opening threshold, the one or more pins 242 are broken, e.g., sheared off. As shown in fig. 8c, the pin 242 is in a broken state, at which time the valve member 240 is removed from the third bore 238H of the third annular member 238.

Thus, to break one or more pins 242 to cause fluid valve 230 to open, a sufficient fluid pressure may be applied from the inner cavity C of base pipe 110 to a first side of valve member 240 that is greater than the fluid pressure applied from annular space 124 to a second side of valve member 240 to reach or exceed a predetermined opening threshold.

In one embodiment, the valve member 240 may be made of any suitable material having suitable strength and being fluid-tight, such as stainless steel, aluminum alloys, carbon fiber materials, ceramic materials, and polymeric materials (e.g., PET, etc.). The pin 242 may be made of any suitable material having suitable strength.

In one embodiment, as shown in fig. 8b, the second diameter of the second bore 236H of the second annular member 236 may be less than the third diameter of the third bore 238H of the third annular member 238 such that a shoulder 244 is formed between the second and third

annular members

236, 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 may only move in the direction of the annular space 124 (in the event that one or more pins 242 are broken) and not in the opposite direction.

Fig. 9a-9b illustrate a schematic view of an embodiment of a pin 242, wherein the pin 242 includes a weakened portion 242W, which may be a missing portion of material in the pin 242. In the embodiment shown in fig. 9a, the weakened portion 242W may be one or more spaced apart recesses pre-machined in the outer surface of the pin 242, which may be arranged in an annular pattern along the circumferential direction of the outer surface of the pin 242. In the embodiment shown in fig. 9b, 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 from a lower strength material. For example, the reduced strength portion may be made of a material that is less strong than the material of other portions of the pin 242, and/or one or more regions of the pin 242 may be treated to be reduced in 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 stronger materials without causing excessive fluid pressure to be applied when breaking the pin 242.

In one embodiment, the

fluid valve

130, 230 may further include a flow restricting member 146, 246 fitted within the interior cavity of the

valve body

132, 232 for restricting the flow of fluid through the

fluid valve

130, 230. The flow restricting member may comprise an annular member having an inner bore that may be smaller in diameter than the inner bore of the other member of the

fluid valve

130, 230. In fig. 5b, one of the first and second

annular members

134, 136 may act as a flow restriction member. In fig. 8b, one of the second and third

annular members

236, 238 may act as a flow restriction member. Alternatively, the

fluid valves

130, 230 may include separate flow restricting members. Fig. 10a schematically illustrates the flow restriction member 146 fitted in the interior cavity of the valve body 132, and fig. 10b schematically illustrates the flow restriction member 246 fitted in the interior cavity of the valve body 232.

In one embodiment, where the flow control screen 100 includes two or more fluid valves, the predetermined opening thresholds of at least two of the 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 can be made to open at a different pressure. That is, a smaller pressure may be applied first to open a fluid valve having a lower predetermined opening threshold, and then a larger pressure may be applied to open a fluid valve having a higher predetermined opening threshold.

11a-11b schematically illustrate one embodiment of a well structure including a flow control screen according to the present invention. FIG. 11a shows a horizontal well configuration wherein the flow control screens are arranged in a horizontal direction. FIG. 11b shows a vertical well configuration in which the flow control screens are arranged in a vertical orientation. Additionally, the well structure of the present invention may also be a directional well structure wherein the flow control screens are arranged in an inclined orientation. As shown in fig. 11a-11b, a well structure 1000 may include a well wall 1010, one or more of the flow control screens 100 described above, and a continuous packer 1020. The well wall 1010 defines a wellhead 1030 open to the surface. The flow control screens 100 are arranged in series within the wellbore wall 1010 such that the inner cavities of the base pipes of the flow control screens communicate with each other to collectively form a transfer passage 1040 for transferring fluid from downhole to the wellhead 1030. The continuous packer 1020 may be formed of packing particles and fills the annular space between the flow control screen 100 and the wellbore wall 1010. During production, the continuous packer 1020 can block the high flow of water from the hypertonic section from flowing axially without creating a cross-flow.

Figures 12a-12b schematically illustrate one embodiment of a well structure including a flow control screen according to the present invention. FIG. 12a shows a horizontal well configuration wherein the flow control screens are arranged in a horizontal direction. FIG. 12b shows a vertical well configuration in which the flow control screens are arranged in a vertical orientation. Additionally, the well structure of the present invention may also be a directional well structure wherein the flow control screens are arranged in an inclined orientation. As shown in FIG. 12, well structure 2000 may include a well wall 2010, one or more of the above-described flow control screens 100, and a packer 2020 disposed between each two adjacent flow control screens 100. The well wall 2010 defines a wellhead 2030 that opens to the surface. Flow control screens 100 are placed in series within well wall 2010 such that the inner cavities of the base pipes of the flow control screens communicate with each other to collectively form a transfer passage 2040 for transferring fluid from downhole to wellhead 2030. Packer 2020 may be configured to axially seal off the annular space between flow control screen 100 and well wall 2010 from each other. During production, the packer 2020 can block the high flow of water from the hypertonic section from flowing axially without creating a cross-flow.

In the production process using the well configuration of fig. 11a-11b or fig. 12a-12b, at later stages of production, with more and more well sections, and even the entire well section, flooded to different degrees, it is necessary to bring oil out of the water, i.e., to increase the flow rate from the formation into the flow control screen. At this time, a certain pressure may be applied to the

transfer passages

1040, 2040 from the wellhead using the pressurizing apparatus 200. Pressure applied from the wellhead to the

transfer passages

1040, 2040 is applied to the first side S of each

fluid valve

130, 230 via each through-hole 114, each fluid passage 126 in the base pipe 110 of each flow control screen 100₁. Each

fluid valve

130, 230 is on the first side S₁Are subjected to the same pressure. If the difference between the pressure and the pressure of the fluid from the annular space 124 (i.e., the pressure minus the pressure from the annular space)124) is greater than or equal to a predetermined opening threshold of at least one fluid valve, the at least one fluid valve is opened while the remaining fluid valves remain closed. Because at least one fluid valve (which is otherwise closed) is opened by surface pressurization, additional fluid communication is provided in the flow control screen (from the annular space through the open fluid valve into the inner cavity of the base pipe) to increase the flow from the formation into the flow control screen.

Next, as production continues, there is a need to further increase the flow from the formation into the flow control screen. At this point, a higher pressure may be applied from the wellhead to the

transfer passages

1040, 2040 using the pressurization device 200 to open at least one fluid valve having a higher predetermined opening threshold to further increase the flow from the formation into the flow control screen.

By setting the predetermined opening thresholds of the fluid valves in the flow control screens to different sizes, the fluid valves in the flow control screens may be opened in stages and in batches by applying a pressure that increases from small to large via the wellhead using the pressurizing apparatus 200 as needed. In this way, the flow from the formation into the flow control screen can be increased in stages and in batches to meet the requirements at different stages of the later stage of production.

Example 1

A new well is arranged in a certain offshore oil field, the oil layer of the new well has the viscosity of 142 centipoises, the viscosity of formation water is 0.9 centipoises, the oil-water viscosity ratio is 158, the diameter of a horizontal section well shaft is 6 inches, and the length of the horizontal section is 1000 meters. A well structure according to the utility model is run, comprising 100 flow control screens according to the utility model, each flow control screen comprising three fluid valves having a predetermined opening threshold of 5MPa, 12MPa and 17MPa, respectively. Thus, the entire 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 17 MPa.

The daily liquid production is 176 square/day, the daily oil production is 172 square/day, the water content is 2.3 percent, and the production pressure difference is 3 MPa. After 20 months of stable yield, the water content gradually rises to 80 percent. Through comprehensive analysis, the pump and the ground processing equipment meet the conditions of the extracting solution, the first ground pressurization is determined to be carried out, the pressurization is carried out to 6MPa, and 100 fluid valves with the preset opening threshold value of 5MPa are opened.

Then, the mixture is put into an electric submersible pump for production, wherein the daily yield is 321 square/day, the daily yield is 67 square/day, and the water content is 79.1 percent. The water content is slightly reduced at the initial stage of the measure, and the production pressure difference is 3.3 MPa.

After 16 months of stable production, the well water content rose to 90%. After comprehensive analysis, the extraction solution production stabilizing measure is adopted again, the second ground pressurization is determined to be implemented, the pressurization is carried out to 14MPa, and 100 fluid valves with the preset opening threshold value of 12MPa are opened.

Then, the pump is replaced, the well is opened for production, the daily liquid production is 612 square/day, the daily oil production is 54 square/day, the water content is 91.2 percent, and the production pressure difference is 3.5 MPa.

After 12 months of continuous production, the water content rose to 98%. After comprehensive analysis, the extraction solution production stabilizing measure is adopted again, the third ground pressurization is determined to be implemented, the pressurization is carried out to 20MPa, and 100 fluid valves with the preset opening threshold value of 17MPa are opened.

Then, the electric submersible pump is started to produce, the daily liquid yield is 1000 square/day, the daily oil yield is 20 square/day, the water content is 98 percent, and the production pressure difference is 3.9 MPa.

Compared with the adjacent well adopting the conventional technology in the same period, the adjacent well adopting the conventional technology has the initial water content of about 40 percent and the water content rapidly rises to about 70 percent after one month, and the oil well structure adopting the utility model has the advantages of long waterless oil production period and slow rising of the upper water, particularly can improve the liquid supply capacity of the flow control sieve tube for multiple turns as required in the later period, meets different requirements of extracting solutions in different stages and ensures the daily oil production. The well structure according to the utility model accumulates 4.47 x 104 squares more oil than an adjacent well using conventional technology at the same time.

Example 2

An oil field has an old well, a 8.5 inch well hole and a horizontal section 400 meters long. And 5.5 inch sieve tube simple sand control completion is started in the early stage. After 90 days of the waterless oil production period, low liquid volume, high water content and high production pressure difference occur, the daily production liquid is 80 square/day, the water content rapidly rises to 96 percent, and the well is shut down.

The comprehensive analysis considers that the main reasons of the production stop of the well are partial water outlet and the blockage of the original screen pipe, and water control, sand control and oil increase are required to be implemented.

The original screen is perforated, i.e. a plurality of radial channels are formed, so that the screen loses the flow control capability. Then, 40 flow control screens according to the present invention were placed in series inside the original screen such that the inner cavities of the base pipes of the 40 flow control screens were in communication with each other to collectively form a transfer passage for transferring fluid from downhole to wellhead. Packing particles are then used to fill the annular space between the original screen and the borehole wall and to fill the annular space between the original screen and the 40 flow control screens.

Each flow control screen includes three fluid valves having predetermined opening thresholds of 7MPa, 10MPa, and 15MPa, respectively. Thus, the modified well structure comprises 40 fluid valves with a predetermined opening threshold of 7MPa, 40 fluid valves with a predetermined opening threshold of 10MPa and 40 fluid valves with a predetermined opening threshold of 15 MPa.

And (3) putting a pump down for production, wherein after the well is opened, the daily produced fluid is 180 square/day, the daily produced oil is 65 square/day, the water content is 63.9 percent, and the production pressure difference is 2.8 MPa. After 15 months of stable yield, the water content gradually rises to 81%. Through analysis, the liquid production rate needs to be increased, the first ground pressurization is determined, the pressurization is carried out to 8MPa, and 40 fluid valves with preset opening threshold values of 7MPa are opened.

Then, the mixture is put into an electric submersible pump for production, wherein the daily yield is 350 square/day, the daily yield is 63 square/day, the water content is 82 percent, and the production pressure difference is 3.3 MPa.

After 12 months of stable production, the well water content rose to 90%. After comprehensive analysis, the extraction solution production stabilizing measure is adopted again, the second ground pressurization is determined to be implemented, the pressurization is carried out to 12MPa, and 40 fluid valves with the preset opening threshold value of 10MPa are opened.

Then, the pump is replaced, the well is opened for production, the daily liquid production is 630 square/day, the daily oil production is 49 square/day, the water content is 92.2 percent, and the production pressure difference is 3.7 MPa.

The yield is stable for 10 months, and the water content slowly rises to 98 percent. And (4) taking a liquid extract production stabilizing measure again, determining to implement ground pressurization for the third time, pressurizing to 18MPa, and opening 40 fluid valves with preset opening thresholds of 15 MPa.

And (4) well opening production, wherein the daily liquid yield is 900 square/day, the daily oil yield is 25 square/day, and the production pressure difference is 4.3 MPa. The oil is increased by 3.56X 104 square.

The present invention provides a flow control screen for an oil well, and provides an oil well structure employing the flow control screen.

According to the utility model, the liquid supply capacity of the underground flow control sieve tube can be adjusted by surface pressurization, and the method has the following advantages: (1) the structure is simple, and the implementation risk is low; (2) compared with the mode of improving the flow conductivity of the sieve tube by adopting the perforation, the sand control sieve tube can prevent sand, and the perforation has the risk of blocking a gun and producing sand; (3) compared with the method for adjusting the flow guide capacity of the sieve tube by additionally installing the sliding sleeve, the method does not need to take an electric pump and a pipe column above the electric pump and also does not need to put a special tool pipe column for opening the sliding sleeve, has simple and reliable structure, can realize step-by-step opening of the standby channel only by ground pressurization, and occupies less manpower and material resources and has less operation time; (4) the adaptability is strong, and the flow guide capability of the flow control sieve tube can be adjusted by applying the utility model to both a vertical well and a horizontal well (including a directional well); (5) the flow-control sieve tube flow-guiding capacity can be adjusted step by step and in batches, the daily oil yield of the oil well is obviously improved, and the effective production time of the oil well is prolonged.

While the present invention has been described with reference to exemplary embodiment(s), it will be understood by those skilled in the art that the utility model is not limited to the precise construction and components described herein and that various modifications, changes, and variations may be apparent from the foregoing descriptions without departing from the spirit and scope of the utility model as defined in the appended claims. The present invention is not limited by the illustrated ordering of steps, as some steps may occur in different orders and/or concurrently with other steps. Therefore, it is intended that the utility model not be limited to the particular embodiment(s) disclosed, but that the utility model 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 comprising a fluid-tight pipe wall defining an internal cavity, the base pipe having one or more through-holes formed in the pipe wall;

a hollow filter tube comprising a fluid permeable tube wall, the filter tube disposed around an 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, one or more fluid passages being defined between the annular space and an inner cavity of the base tube; and

one or more fluid valves, each of the one or more fluid valves 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 an 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 channels, and

wherein each of the one or more fluid valves has a respective predetermined opening threshold and is configured to open a corresponding fluid passage when a fluid pressure differential between a fluid pressure applied to a first side of the fluid valve from an inner chamber of the base pipe and a fluid pressure applied to a second side of the fluid valve from the annular space is greater than or equal to the respective predetermined opening threshold, such that fluid in the annular space is able to flow into the inner chamber of the base pipe via the corresponding fluid passage.

2. The flow control screen as recited in claim 1 wherein each of the one or more fluid valves is disposed in or adjacent a corresponding one of the one or more through-holes of the base pipe to block or allow fluid to enter an inner cavity of the base pipe through the through-hole.

3. The flow control screen as recited in 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 provided at intervals in a longitudinal direction of the base pipe.

4. The flow control screen as recited in claim 1 wherein the base pipe wall comprises a first section and an adjacent second section, the one or more through-holes being formed in the first section at intervals in the circumferential direction, the filter pipe being disposed around the outside of at least a portion of the second section; and is

Wherein the flow control screen further comprises a hollow end ring fitted outside at least a portion of the first section and connected to the filter tube, a tube wall of the end ring having one or more axial bores in fluid communication with the annular space and one or more radial bores, each of the one or more radial bores of the end ring fluidly connecting a corresponding one of the one or more axial bores of the end ring to a corresponding one of the one or more through-bores of the base pipe, thereby defining the one or more fluid passages.

5. The flow control screen as recited in 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 as recited in any of claims 1-5 wherein each of the one or more fluid valves comprises:

a first annular member facing the annular space, the first annular member defining a first bore extending through the first annular member, the first bore of the first annular member having a first diameter;

a second annular member defining a second bore extending therethrough, the second bore of the second annular member having a second diameter;

a valve member sandwiched between the first and second annular members, 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 broken to open the corresponding fluid passage when the fluid pressure differential is greater than or equal to a predetermined opening threshold.

7. The flow control screen as recited in claim 6 wherein the valve member comprises a weakened section.

8. The flow control screen as recited in 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 contactable with fluid from the inner cavity of the base pipe and the second side having a second fluid contact area contactable with fluid from the annular space, and wherein the first fluid contact area is less than the second fluid contact area.

9. The flow control screen as recited in 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 contactable with fluid from the inner cavity of the base pipe and the second side having a second fluid contact area contactable with fluid from the annular space, and wherein the first fluid contact area is less than the second fluid contact area.

10. The flow control screen as recited in any of claims 1-5 wherein each of the one or more fluid valves comprises:

a third annular member defining a third bore extending therethrough, the third bore of the third annular member having a third diameter, the third annular member being sandwiched between the first and second annular members;

a valve member fitted in a third bore of the third annular member, the valve member being fluid-tight;

one or more pins disposed in the third annular member at intervals in a circumferential direction and extending into the valve member in a radial direction to fix 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 broken when the fluid pressure differential is greater than or equal to a predetermined opening threshold such that the valve member is removed from the third bore of the third annular member, thereby opening the corresponding fluid passage.

11. The flow control screen as recited in claim 10 wherein the second diameter is less than the third diameter.

12. The flow control screen as recited in claim 10 wherein at least one of the one or more pins comprises a weakened section.

13. The flow control screen as recited in claim 1 wherein at least one of the one or more fluid valves further comprises a flow restricting member fitted within an interior cavity of a valve body of the at least one fluid valve for restricting fluid flow through the at least one fluid valve.

14. The flow control screen as recited in claim 1 wherein the flow control screen comprises two or more fluid valves, the predetermined opening thresholds of at least two of the two or more fluid valves being different from each other.

15. An oil well structure characterized by comprising:

a well wall defining a wellhead open to the surface;

the flow control screen or screens as recited in any one of claims 1-14, the one or more flow control screens being serially disposed within the wellbore wall such that inner cavities of base pipes of the one or more flow control screens communicate with each other to collectively form a transfer passage for transferring fluid from downhole to uphole; and

an packer formed of packing particles that fills an annular space between the one or more flow control screens and the wellbore wall.

16. An oil well structure characterized by comprising:

a well wall defining a wellhead open to the surface;

a packer disposed between each two adjacent flow control screens, the packer configured to axially seal off an annular space between the one or more flow control screens and the borehole wall from each other.