PACK SCREEN AND BYPASS CONNECTOR CONFIGURED TO CONNECT TO PACK SCREEN

Abstract

A park screen has a base tube, a communication layer and a protective tube arranged in sequence from an inner side to an outer side thereof. At least one first through hole is arranged on the base tube, and at least one second through hole is arranged on the protective tube. The communication layer includes a packing tube and a sand filter arranged in juxtaposition along a circumferential direction. At least one third through hole is arranged on a wall of the packing tube and in fluid communication with the second through hole. The fluid from the packing tube flows out of the pack screen through the third through hole and the second through hole. The sand filter is configured to cover the first through hole on the base tube so that the fluid enters the base tube via the first through hole after flowing through the sand filter.

Description

CROSS REFERENCE OF RELATED APPLICATIONS

The present application claims the priority of Chinese patent application No. 202211640087.X entitled “Large-drift-diameter pack screen and bypass connector used for connecting pack screens” and filed on Dec. 20, 2022, the entire content of which is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the technical field of oil-gas well development, and specifically to a pack screen and a bypass connector configured to connect to pack screens.

TECHNICAL BACKGROUND

Gravel packing for horizontal well is a commonly method of sand control and completion in the field of oil-gas field development. That is, a completion string connected to a sand control screen is lowered into the well and in place within the horizontal production section. Then, mortar is pumped from the ground to the downhole. The mortar is introduced into an annulus between the screen and the wellbore wall. Due to the settlement of solid phase and the filtration of the screen, the gravels in the mortar are gradually separated out and accumulate in the annulus between the screen and the wellbore wall, forming a gravel packing layer that serves as a filtering medium to prevent formation sand from entering the wellbore in subsequent production. The sand-carrying fluid after sand separation flows through the filter layer of the screen to enter the screen, and finally returns to the ground.

The annulus outside the screen is the main circulation passage in the gravel packing. Since the length of the horizontal production section is usually measured in hundreds of meters, or even more than one thousand meters, there are various factors that may lead to uneven distribution along the wellbore axis. For example, such factors comprise: change in the flow area of the annulus caused by uneven outer diameter of tools; change in the leakage rate of the mortar caused by uneven permeability distribution and micro-fracture in local areas of the well section; and local shale segments that are prone to expansion. These factors exacerbate changes in the sand ratio when the mortar flows and also the amplitude of changes in the flow rate of the mortar, which may lead to premature settlement and accumulation of gravels in local areas of the well section that may form bridge blinding. As a result, the subsequent mortar cannot continue to be transported forward, so that the construction has to be terminated prematurely. In this case, unfilled areas are left in the production section, resulting in failure of short-term sand control after production that seriously affects oil-gas production.

Aimed at addressing the problem of bridge blinding, CN110593825A discloses a gravel packing screen for horizontal well with bypass pipeline. The packing screen is integrated with a bypass packing pipe and a conveying pipe, wherein the conveying pipes of multiple screens are connected through a coupling bypass joint to form a bypass pipeline within the completion string of the horizontal well along an entire span thereof. Even if bridge blinding is formed in the annulus outside the screen, the mortar can still bypass the bridge blinding and continue to be transported forward for filling, thus eliminating the unfilled areas outside the screen and effectively improving the gravel packing efficiency.

However, the packing screen in the above prior art requires a bypass pipe arranged between a sand control screen and an outer protective pipe, which increases the thickness of the packing screen considerably, resulting in the reduced internal diameter and the limited space for subsequent downhole operations. As a result, a wider application of the related products in the oilfield would be difficult to realize. For example, an outer diameter of the screen lowered in a 9.5-inch open-hole wellbore is 200 mm, with a base pipe thereof only of 5.5-inch. If heavy-oil thermal recovery operation needs to be carried out, a 4.5-inch insulation tubing cannot be lowered into the wellbore.

Therefore, there is an urgent need for a large-drift-diameter continuous gravel pack screen that not only has a suitable outer diameter for entering the well but also can provide sufficient space for subsequent downhole operations.

SUMMARY OF THE INVENTION

In view of the above technical problems, the present invention proposes a pack screen with a large drift diameter that facilitates various downhole operations after production.

The present invention further proposes a bypass connector configured to connect pack screens according to the present invention.

According to the present invention, a pack screen is proposed, comprising a base tube, a communication layer and a protective tube arranged in sequence from an inner side to an outer side thereof, wherein at least one first through hole is arranged on the base tube, and at least one second through hole is arranged on the protective tube, the communication layer comprising a packing tube and a sand filter arranged in juxtaposition along a circumferential direction, wherein at least one third through hole is arranged on a wall of the packing tube and in fluid communication with the second through hole, so that fluid from the packing tube flows out of the pack screen through the third through hole and the second through hole; and the sand filter is configured to cover the first through hole on the base tube, so that the fluid enters the base tube via the first through hole after flowing through the sand filter.

In one specific embodiment, a flow-through channel in communication with the third through hole is arranged between the protective tube and the base tube.

In one specific embodiment, the communication layer further comprises a conveying tube, wherein the conveying tube and the packing tube are spaced apart and alternately arranged between adjacent sand filters.

In one specific embodiment, one end of the flow-through channel is in communication with the third through hole on the packing tube, and another end thereof extends to a side wall of the conveying tube, wherein a side wall of the flow-through channel is in fluid communication with the second through hole.

In one specific embodiment, the flow-through channel is in a spiral shape, wherein an end of the flow-through channel close to the packing tube is higher than an end close to the conveying tube.

In one specific embodiment, a packing groove is arranged between the flow-through channel and the sand filter.

In one specific embodiment, the packing groove comprises an arc-shaped bottom plate in contact with the base tube; arc-shaped groove plates arranged on both sides along a length direction of the arc-shaped bottom plate and configured to support the protective tube; and a fourth through hole arranged at an end portion of the packing groove for communicating with the third through hole.

In one specific embodiment, cross sections of the packing tube and the conveying tube are each in a shape of a trapezoid, wherein a short side of the trapezoid fits a radian of the protective tube, while a long side thereof fits a radian of the base tube, the third through hole of the packing tube being provided on two waists of the trapezoid.

In one specific embodiment, a second insertion sleeve is provided at an upper portion of the base tube, wherein a lower end of the second insertion sleeve is connected to and in fluid communication with the packing tube and the conveying tube.

In one specific embodiment, a first insertion sleeve is provided at a lower portion of the base tube, an upper end of the first insertion sleeve being connected to the packing tube and the conveying tube, wherein a lower end of the packing tube is sealed by the first insertion sleeve, and the conveying tube is in fluid communication with the first insertion sleeve.

In one specific embodiment, insertion grooves are provided on the first insertion sleeve and the second insertion sleeve, for receiving the conveying tube, the packing tube and the protective tube, respectively.

The present invention further proposes a bypass connector for connecting two pack screens according to the present invention, comprising: a coupling, for connecting the base tubes of the two pack screens; a bypass tube arranged outside the base tube, wherein an upper end of the bypass tube is connected to the conveying tube of an upper, first pack screen through the first insertion sleeve thereof, and a lower end of the bypass tube is connected to the packing tube and the conveying tube of a lower, second pack screen through the second insertion sleeve thereof, and a connection mechanism arranged between the second insertion sleeve of the second pack screen and the first insertion sleeve of the first pack screen, and configured to extend and contract along an axis direction, so that the bypass tube is inserted into the second insertion sleeve of the second pack screen and the first insertion sleeve of the first pack screen.

In one specific embodiment, the connection mechanism is arranged between the bypass tube and the first insertion sleeve of the first pack screen, or between the bypass tube and the second insertion sleeve of the second pack screen.

In one specific embodiment, the connection mechanism comprises: a connection sleeve connected to the bypass tube; and a spinning sleeve for connecting the first insertion sleeve and the connection sleeve, wherein the spinning sleeve is connected to the first insertion sleeve of the first pack screen through threads, axially connected to the connection sleeve through insertion in a sealed manner, and configured to adjust a length of the connection mechanism through circumferential rotation relative to the first insertion sleeve of the first pack screen, so that the bypass connector engages with the first pack screen and the second pack screen.

In one specific embodiment, the bypass connector further comprises a clamp clamped outside the base tube, for fixedly connecting the bypass tube to the base tube and/or the coupling.

In one specific embodiment, at least two wear-resistant plates are arranged on an outer side of the bypass tube along a length direction thereof.

In one specific embodiment, at least two pads are arranged on an inner side of the bypass tube along the length direction thereof.

Compared with the prior arts, the present invention has the following advantages.

In the present invention, the packing tube, the conveying tube and the sand filter are arranged on a same radial plane, so that the mortar can pass smoothly without affecting the diameter of the pack screen. Therefore, when outer dimensions are the same, the pack screen in the present invention can have a larger inner diameter compared with those in the prior arts.

The pack screen according to the present invention further comprises a flow-through channel and a packing groove. The flow-through channel enables the mortar to spray circumferentially during the packing procedure, so as to achieve uniform circumferential packing of the screen and avoid formation of gaps. The packing groove can separate the flow-through channel from the sand filter, preventing the mortar in the flow-through channel from being deposited therein due to premature filtration, thus preventing the blockage of the flow-through channel.

In normal applications, multiple screens are usually connected in series and lowered into the well together. According to the present invention, the bypass connector connects two pack screens in series, wherein bases tubes of the two pack screens are connected through a coupling, and the packing tubes and the conveying tubes of the two pack screens are connected through a bypass tube and a connection mechanism. The connection mechanism is configured to adjust the length of the pack screen in a spiral manner, thus realizing circumferential alignment and the rapid connection between the pack screens.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described below with reference to the accompanying drawings.

FIG. 1 schematically shows a pack screen connected to a bypass connector according to one embodiment of the present invention.

FIG. 2 schematically shows the pack screen according to one embodiment of the present invention, wherein a protective tube is shown only at a lower half thereof.

FIG. 3 schematically shows the pack screen according to one embodiment of the present invention, but without a sand filter and the protective tube thereof.

FIG. 4 schematically shows a packing tube of the pack screen according to one embodiment of the present invention.

FIG. 5 schematically shows a conveying tube of the pack screen according to one embodiment of the present invention.

FIG. 6 schematically shows a packing groove of the pack screen according to one embodiment of the present invention.

FIG. 7 schematically shows the protective tube of the pack screen according to one embodiment of the present invention.

FIG. 8 is a sectional view schematically showing a first insertion sleeve according to the present invention.

FIG. 9 is a sectional view schematically showing a spinning sleeve according to the present invention.

FIG. 10 is a sectional view schematically showing a connection sleeve according to the present invention.

FIG. 11 is a sectional view schematically showing a bypass tube according to the present invention.

FIG. 12 is a sectional view schematically showing a second insertion sleeve according to the present invention.

FIG. 13 schematically shows a sealing gasket according to one embodiment of the present invention.

FIG. 14 schematically shows clamps according to one embodiment of the present invention.

FIG. 15 schematically shows clamps according to another embodiment of the present invention.

FIG. 16 schematically shows a structure of the bypass connector according to the present invention.

FIG. 17 schematically shows a principle of the packing procedure according to the present invention.

In the present application, all accompanying drawings are schematic ones, provided to illustrate the principle of the present invention merely, and are not necessarily drawn to actual scale.

DETAILED DESCRIPTION OF EMBODIMENTS

The present invention will be described below with reference to the accompanying drawings.

It should be noted that in the present application, directional terms or determiners such as “upper”, “lower”, etc. are defined with reference to FIG. 1. The directional term “inner” used herein refers to a direction close to a central axis of a pack screen, and “outer” refers to a direction away from the central axis of the pack screen. The above terms are not intended to limit absolute positions of the components involved, but may be varied according to specific circumstances.

FIG. 1 schematically shows a pack screen 100 connected to a bypass connector 200 according to one embodiment of the present invention. In FIG. 1, pipe sections with identical structures are omitted, in order to clearly show an overall connection between the pack screen 100 and the bypass connector 200. As shown in FIG. 1, an upper end and a lower end of the bypass connector 200 are respectively connected to the pack screens 100, so that multiple pack screens 100 connected in series can enter the well.

FIG. 2 schematically shows the pack screen 100 according to one embodiment of the present invention. For a protective tube 7 of the pack screen 100, only a lower half thereof is shown in FIG. 2, in order to show an internal structure of the pack screen 100. FIG. 3 schematically shows the pack screen 100 according to one embodiment of the present invention, but with a sand filter 6 of the pack screen 100 and the protective tube 7 removed.

As shown in FIGS. 1, 2 and 3, the pack screen 100 includes a base tube 1, an assembly, and the protective tube 7 arranged in sequence from an inner side to an outer side thereof. A plurality of first through holes 101 are provided on a wall of the base tube 1, and a plurality of second through holes 701 are provided on a wall of the protective tube 7. The assembly includes the sand filter 6 and at least one packing tube 3 arranged on a same radial plane. Specifically, as shown in FIGS. 1 to 3, a plurality of packing tubes 3 is evenly arranged in a circumferential direction in an annular space between the base tube 1 and the protective tube 7, and all arranged along an axial direction. As shown in FIG. 4, a plurality of third through holes 301 is evenly arranged along the axial direction on a wall of each packing tube 3. The annular space between the base tube 1 and the protective tube 7 is filled with the sand filter 6 except for the position where the packing tube 3 is located, so that the sand filter 6 and the packing tube 3 are arranged on the same radial plane. The sand filter 6 is arranged to cover all the first through holes 101 of the base tube 1.

It is readily understood that the second through holes 701 and the third through holes 301 can allow all the pumped mortar to pass through. With such arrangement, the mortar can be transported to the downhole by the packing tube 3, flow out through the third through holes 301 on the wall of the packing tube 3, and then flow into an annular space between the protective tube 7 and the wellbore (not shown) through the second through holes 701 on the wall of the protective tube 7. When the mortar flows in a radial direction towards the inner side of the pack screen 100, the sand phase of the mortar will be filtered by the sand filter 6 that covers all the first through holes 101 on the base tube 1. Finally, the sand phase of the mortar remains in the annular space between the pack screen 100 and the wellbore, while sand-free liquid of the mortar enters the base tube 1 through the sand filter 6 and the first through holes 101 of the base tube 1, and is finally discharged from the wellhead.

A specific cross section of the packing tube 3 is not limited to the shape according to this embodiment. In this embodiment, as shown in FIG. 4, the cross section of the packing tube 3 is in a shape similar to an isosceles trapezoid. Specifically, a surface of the packing tube 3 in contact with the protective tube 7 is an arc-shaped surface that fits an inner surface of the protective tube 7, and a surface of the packing tube 3 in contact with the base tube 1 is an arc-shaped surface that fits an outer surface of the base tube 1, wherein a width of the surface of the packing tube 3 in contact with the protective tube 7 is narrower than that of the surface of the packing tube 3 in contact with the base tube 1. In this embodiment, the third through holes 301 are rectangular, arranged in sequence along the axial direction on two side surfaces of the packing tube 3. As shown in FIG. 2, a flow-through channel 601 correspondingly connected to the third through holes 301 is arranged between the protective tube 7 and the base tube 1. The sand filter 6 is filled between the protective tube 7 and the base tube 1 except for the positions where the packing tube 3 and the flow-through channel 601 are located, so that all the first through holes 101 of the base tube 1 are covered by the sand filter 6.

With such arrangement, the mortar in the packing tube 3 flows out through the third through holes 301 arranged on the side surfaces thereof and along the flow-through channel 601, then passes through the second through holes 701 on the protective tube 7 to flow into the annular space between the pack screen 100 and the wellbore. The third through holes 301 arranged on the side surfaces can effectively prevent blockage. In the meantime, the flow-through channel 601 can guide the mortar, expanding a circumferential flow range thereof as much as possible. Such arrangement allows for rapid packing of the mortar, while effectively preventing the third through holes 301 from being blocked.

In a preferred embodiment, a plurality of axial conveying tubes 4 is evenly distributed in the circumferential direction between the base tube 1 and the protective tube 7. The conveying tubes 4 and the packing tubes 3 which are equal in number are arranged alternately. In this embodiment, two conveying tubes 4 and two packing tubes 3 are provided, with a phase angle of 90° therebetween. The conveying tubes 4 are configured to continuously convey the mortar downward, and the packing tubes 3 are configured to transport the mortar into the annular space between the pack screen 100 and the wellbore.

The specific cross section of the conveying tube 4 is not limited to the shape according to this embodiment. In this embodiment, as shown in FIG. 5, the conveying tube 4 has a shape similar to that of the packing tube 3, but is configured to convey the mortar downward only. Therefore, no through holes are provided on the wall of the conveying tube 4.

A packing groove 5 is arranged on the flow-through channel 601. In one preferred embodiment, both the flow-through channel 601 and the packing groove 5 are in spiral shapes. One end of the packing groove 5 abuts against the packing tube 3, and the other end thereof abuts against the conveying tube 4. The end of the packing groove 5 close to the packing tube 3 is higher than the end thereof close to the conveying tube 4. The packing groove 5 includes an arc-shaped bottom plate 502 and arc-shaped groove plates 501. The arc-shaped bottom plate 502 fits an outer wall of the base tube 1 in shape. The arc-shaped groove plates 501 are fixedly arranged on both sides of the arc-shaped bottom plate 502 to separate the flow-through channel 601 from the sand filter 6, preventing the mortar from being filtered from the side of the sand filter 6 and thus accumulating in the flow-through channel 601. Meanwhile, the arc-shaped groove plates 501 can support the protective tube 7. That is, a radially outer face of the arc-shaped groove plate 501 abuts against the protective tube 7, and a radially inner face thereof abuts against the base tube 1. Fourth through holes 503 in communication with the third through holes 301 are provided at the end of the packing groove 5 close to the packing tube 3.

The packing groove 5 can support the protective tube 7. Moreover, the packing groove 5 is arranged between and thus separates the sand filter 6 and the flow-through channel 601. After flowing through the third through holes 301 of the packing tube 3 into the flow-through channel 601, the mortar must first flow through the second through holes 701 of the protective tube 7 into the annular space between the pack screen 100 and the wellbore, and then enter the base tube 1 through the second through holes 701 of the protective tube 7 and the sand filter 6 in sequence. Therefore, the mortar can be prevented from being directly filtered by the sand filter 6 in the flow-through channel 601 and thus accumulating in and blocking the flow-through channel 601.

In this embodiment, the packing tube 3, the conveying tube 4 and the packing groove 5 are all fixedly connected to the base tube 1 through welding. The specific shape of the sand filter 6 is determined according to the shape of the remaining space in the packing tube 3, the conveying tube 4 and the packing groove 5. The first through holes 101 on the base tube 1 all correspond to the sand filter 6 in terms of position, ensuring that all the first through holes 101 can be covered by the sand filter 6. The sand filter 6 is fixed to the base tube 1 by adhesive. The protective tube 7 is sleeved around and fixed to an outermost part of the pack screen 100 through welding. Of course, one skilled in the art can also understand that the above components can be fixedly connected to each other by other means.

As shown in FIG. 7, in this embodiment, the protective tube 7 is formed by curling and welding a long strip of sheet material, with a weld seam in a spiral shape. There are various means to form the protective tube 7, which are not limited to the welding in this embodiment.

As shown in FIGS. 2 and 3, in a specific embodiment of the present invention, a length of the protective tube 7 is less than that of the base tube 1. However, all the first through holes 101 of the base tube 1 are still within the length range of the protective tube 7.

In practice, multiple pack screens need to be connected in series to form a screen string for gravel packing, in order to meet the requirements of long-distance gravel packing. Therefore, in one specific embodiment, an insertion sleeve and the bypass connector 200 are arranged between two adjacent pack screens for connection.

In this embodiment, a first insertion sleeve 8 and a second insertion sleeve 2 are provided at lower and upper ends of the protective tube 7 respectively, wherein both the first insertion sleeve 8 and the second insertion sleeve 2 are hermetically connected to the base tube 1. A lower end of the second insertion sleeve 2 is connected to the packing tube 3 and the conveying tube 4, so that the fluid from the upstream tube can flow into the packing tube 3 and the conveying tube 4 through the second insertion sleeve 2. An upper end of the first insertion sleeve 8 is connected to the packing tube 3 and the conveying tube 4, wherein a lower end of the packing tube 3 is sealed by the first insertion sleeve 8, while the fluid in the conveying tube 4 can flow to the downstream tube through the first insertion sleeve 8.

The bypass connector 200 is provided below the first insertion sleeve 8, and a lower end of the bypass connector 200 is configured to connect to the second insertion sleeve 2 of another pack screen 100 below. Thus, the mortar in the conveying tube 4 from an upstream pack screen 100 can be conveyed through the first insertion sleeve 8, the bypass connector 200 and the second insertion sleeve 2 in sequence into the conveying tube 4 and the packing tube 3 of a downstream pack screen 100.

In one specific embodiment, as shown in FIG. 12, the second insertion sleeve 2 includes an upper ring 202 and a lower ring 201 fixedly arranged from the top to the bottom. An outer diameter of the upper ring 202 is less than that of the lower ring 201. At a top portion of the lower ring 201, a lug 203 is arranged around an outer side of the upper ring 202. Third flow channel holes 204 are axially arranged in the lug 203, for receiving a bypass tube 11 of the bypass connector 200. A third insertion groove 205 and a fourth insertion groove 206 for receiving the packing tube 3 and the conveying tube 4 respectively are arranged in the lower ring 201. Both the third insertion groove 205 and the fourth insertion groove 206 are in communication with the third flow channel holes 204 through a communication groove 208 in the lower ring 201. A second protective insertion groove for receiving the protective tube 7 is arranged on a lower end surface of the lower ring 201.

In one specific embodiment, as shown in FIG. 8, a first annular groove 801 is arranged at a lower portion of the first insertion sleeve 8. Specifically, the lower portion of the first insertion sleeve 8 has a U-shaped structure with an opening facing downwards, so that the first annular groove 801 is formed between two-layer side walls of the U-shaped structure. A first insertion groove 802 for connecting to the packing tube 3 and a second insertion groove 803 for connecting to the conveying tube 4 are arranged at the upper end of the first insertion sleeve 8. In particular, the first insertion groove 802 and the second insertion groove 803 are formed as trapezoids that fit the shapes of the packing tube 3 and the conveying tube 4. A lower end of the first insertion groove 802 is sealed, while a first flow channel hole 804 in communication with the first annular groove 801 is arranged at a lower end of the second insertion groove 803. Therefore, the lower end of the packing tube 3 is blocked after the packing tube 3 is inserted into the first insertion groove 802. However, after the conveying tube 4 is inserted into the second insertion groove 803, the mortar in the conveying tube 4 can flow to a downstream bypass connector 200 through the first flow channel hole 804 and the first annular groove 801.

With such arrangement, when the mortar flows downward from the upstream tube in the second insertion sleeve 2, it will flow into the packing tube 3 and the conveying tube 4 through the second insertion sleeve 2. Since a bottom portion of the packing tube 3 is sealed by the first insertion sleeve 8, the mortar flowing into the packing tube 3 will flow out of the pack screen 100 through the third through holes 301 on the wall of the packing tube 3, thus completing the gravel packing operation. The mortar flowing into the conveying tube 4 can continue to be conveyed downward along the conveying tube 4, providing supply to another pack screen 100 connected downstream.

Specifically, a first protective insertion groove 805 for receiving the protective tube 7 is arranged on an upper end surface of the first insertion sleeve 8. A first sealing groove 806 and a first thread 807 are arranged on an outer wall of the first insertion sleeve 8 from the top to the bottom. The first insertion sleeve 8 is connected to the bypass connector 200 through the first thread 807, forming a sealed connection with the bypass connector 200 through a sealing ring arranged in the first sealing groove 806.

As shown in FIGS. 1 and 16, according to the present invention, the bypass connector 200 includes a coupling 15, a bypass tube 11 and a connection mechanism.

In this embodiment, the coupling 15 is shaped as a cylinder, with threads arranged on an inner wall thereof, for fixedly connecting to the outer walls of the base tubes 1 of the two upper and lower pack screens 100 respectively.

A lower end of the bypass tube 11 is connected to the third flow channel holes 204 on the second insertion sleeve 2 through insertion. A cross section of the bypass tube 11 is in a shape of a fan with rounded ends, which fits the shape of the third flow channel holes 204, so that the bypass tube 11 can be inserted into the third flow channel holes 204. In addition, a sealing gasket 14 as shown in FIG. 13 is provided between the bypass tube 11 and the third flow channel holes 204.

An upper end of the bypass tube 11 is connected to the first insertion sleeve 8 through the connection mechanism that can expand and contract along the axial direction, so that the bypass tube 11 can be installed through insertion. That is, during installation, the lower end of the bypass tube 11 is first inserted into the third flow channel holes 204 of the second insertion sleeve 2. At this time, there is a distance between a lower end of the connection mechanism and the upper end of the bypass tube 11. Next, the lower end of the connection mechanism is moved downward, so that the insertion connection between the connection mechanism and the bypass tube 11 is realized.

As shown in FIGS. 1, 9 and 10, in one specific embodiment, the connection mechanism includes a spinning sleeve 9 and a connection sleeve 10 hermetically sleeved outside the base tube 1, wherein an upper end of the connection sleeve 10 is connected to the first insertion sleeve 8 through the spinning sleeve 9, and a lower end thereof is connected to the bypass tube 11 through insertion. Specifically, the spinning sleeve 9 is connected to the connection sleeve 10 and the first insertion sleeve 8 by different means. For example, the spinning sleeve 9 is connected to one of the connection sleeve 10 and the first insertion sleeve 8 through threads, and abuts against the other along the axial direction. When the spinning sleeve 9 is rotated, the first insertion sleeve 8 and the connection sleeve 10 will move relative to each other, thus realizing the overall expansion and contraction of the connection mechanism.

As shown in FIG. 9, a second thread 901 is provided on an inner wall of the spinning sleeve 9 and engages with the first thread 807 of the first insertion sleeve 8. A spinning sealing ring 16 arranged in the first sealing groove 806 of the first insertion sleeve 8 is hermetically connected to the inner wall of the spinning sleeve 9.

As shown in FIG. 10, a second annular groove 1001 is provided in an upper sleeve wall of the connection sleeve 10, and second flow channel holes 1004 for receiving the bypass tube 11 are provided in a lower sleeve wall thereof, wherein the second flow channel holes 1004 are in communication with the second annular groove 1001. Similarly, the sealing gasket 14 as shown in FIG. 13 is provided between the bypass tube 11 and the second flow channel holes 1004. A third sealing groove 1003 for hermetically connecting to the base tube 1 is provided on an inner wall of the connection sleeve 10, and a base-tube sealing ring 17 is provided in the third sealing groove 1003. A second sealing groove 1002 for hermetically connecting to the inner wall of the spinning sleeve 9 is provided on an upper outer wall of the connection sleeve 10. Meanwhile, a step abutting against a lower end surface of the spinning sleeve 9 is further provided on the outer wall of the connection sleeve 10. With such arrangement, the connection sleeve 10 can rotate circumferentially relative to the spinning sleeve 9, so that the second flow channel holes 1004 of the connection sleeve 10 can be adjusted in terms of their circumferential positions to align with the bypass tube 11, thus facilitating the installation thereof.

In order to facilitate the rotation of the spinning sleeve 9, a plurality of axial ribs 902 is evenly arranged on an outer wall of the spinning sleeve 9 along the circumferential direction. In this manner, the spinning sleeve 9 can be rotated through the ribs 902 and thus move relative to the first insertion sleeve 8. When the spinning sleeve 9 moves downward relative to the first insertion sleeve 8, the connection sleeve 10 can be pushed to move downward, so that the bypass tube 11 below the connection sleeve 10 can be inserted firmly. The spinning sleeve 9 is sleeved outside the first insertion sleeve 8 and the connection sleeve 10, thereby forming an annular space between the spinning sleeve 9 and the base tube 1 for the flow of mortar.

In one preferred embodiment, a clamp is further provided outside the base tube 1 for fixedly connecting the bypass tube 11 to the base tube 1.

Specifically, in this embodiment, a first clamp 12 and a second clamp 13 are further provided. As shown in FIG. 14, the first clamp 12 is arranged outside the base tube 1. The first clamp 12 includes two arc-shaped clamp parts connected by a first hinge seat 1202 and a first hinge shaft 1206. First hinge holes 1203 are axially provided on the first hinge seat 1202, for receiving the first hinge shaft 1206 therein. A first flat shoulder 1204 is provided at another end of each of the two arc-shaped clamp parts. First pass-through holes 1205 are horizontally provided on the first flat shoulder 1204. Bolts 1207 passing through the first flat shoulder 1204 are fixed by nuts 1208. A first arc-shaped groove 1201 for accommodating the bypass tube 11 is provided on each of the arc-shaped clamp parts.

As shown in FIG. 15, the second clamp 13 is arranged in a position where the base tube 1 is connected to the coupling 15. The second clamp 13 includes two arc-shaped clamp parts 1302 connected by a second hinge seat 1304 and a second hinge shaft 1308. Second hinge holes 1305 are axially provided on the second hinge seat 1304, for receiving the second hinge shaft 1308 therein. A second flat shoulder 1306 is provided at another end of each of the two arc-shaped clamp parts 1302. Second pass-through holes 1307 are horizontally provided on the second flat shoulder 1306. Bolts 1207 passing through the second pass-through holes 1307 of the second flat shoulder 1306 are fixed by nuts 1208. A second arc-shaped groove 1301 for accommodating the bypass tube 11 is provided on each of the arc-shaped clamp parts 1302. Meanwhile, a third arc-shaped groove 1303 is provided in a position where the arc-shaped clamps 1302 are connected to the coupling 15.

With reference to FIGS. 1 and 17, the gravel packing procedure after the pack screen 100 is connected to the bypass connector 200 according to this embodiment is described as follows.

As shown in FIG. 17, mortar A is pumped into the bypass connector 200 from upstream. The mortar A is conveyed downward along the bypass tube 11 of the bypass connector 200. After passing through the second insertion sleeve 2, the mortar A is separated into two branches, entering the packing tube 3 and the conveying tube 4 respectively.

The mortar A entering the packing tube 3 flows from the third through holes 301 on the wall of the packing tube 3 into the packing groove 5, passes through the protective tube 7 guided by the packing groove 5, and flows to the annular space outside the protective tube 7 through the second through holes 701 of the protective tube 7. The mortar A undergoes gravitational sedimentation in this annular space, with most of carried gravels remaining therein. The rest of the gravels is filtered when flowing in the radial direction through the sand filter 6, and also remains in this annular space. After the gravels are removed from the mortar A, the mortar A turns into gravel-free fluid B. The gravel-free fluid B passes through the sand filter 6, and then enters the interior of the base tube 1 through the first through holes 101 thereon. Finally, as shown in FIG. 17, the gravel-free fluid B is discharged from an upper part of the base tube 1. That is, all the fluid inside the base tube 1 is the gravel-free fluid B. Since the gravel-free fluid B flowing upward within the base tube 1 cannot be indicated clearly in FIG. 17, only the gravel-free fluid B is indicated in FIG. 17 at a position above the base tube 1.

The mortar A entering the conveying tube 4 continues to be conveyed downward, passes through the first insertion sleeve 8, the spinning sleeve 9 and the connection sleeve 10 in sequence, enters the bypass tube 11 of another bypass connector 200 connected below the connection sleeve 10, and continues to be conveyed downward, repeating the above procedures.

The bypass tube 11, the packing groove 5, the packing tube 3, the conveying tube 4 and the sand filter 6 in the present invention are arranged closely to each other, making full use of the space outside the base tube 1. That is, according to the present invention various components are arranged closely in a position where the sand filter 6 is arranged in the prior arts. Therefore, an outer diameter of the pack screen 100 can be effectively controlled, while ensuring a large drift diameter thereof. In this manner, not only can the string of the pack screen 100 be smoothly lowered into the well, but also sufficient operating space can be ensured for various downhole operations after being lowered into the well.

The packing groove 5 according to the present invention can guide the mortar from the packing tube 3 to spray in the circumferential direction at 360° degrees. As the gravel packing operation continues, the gravels gradually accumulate in the annular space outside the pack screen 100. Such arrangement of the present invention can prevent the rectangular third through holes 301 of the packing tube 3 from being buried.

The bypass connector 200 according to the present invention has the advantages of convenient operation, wear resistance, and good fastening and sealing performance. After inserting the bypass tube 11 into the second insertion sleeve 2 and the connection sleeve 10, the bypass tube 11 can be pressed tightly only by rotating the spinning sleeve 9, thus realizing rapid connection of the bypass pipeline. The bypass tube 11 is fastened by the first clamp 12 and the second clamp 13 to prevent loosening, deformation or even falling off when being lowered into the well.

As shown in FIG. 11, in one preferred embodiment, a wear-resistant plate 1101 is provided at each of axial ends of an outer wall of the bypass tube 11, and at least two pads 1102 are provided on an inner wall of the bypass tube 11 in the axial direction. The wear-resistant plates 1101 can effectively prevent the bypass tube 11 from being worn when being lowered into the well. The pads 1102 can prevent the bypass tube 11 from being extruded and deformed due to radially inward force.

The pressing, fastening, and wear-resistant functions of the bypass tube 11 according to the present invention can ensure that the bypass pipeline has a sealing capacity under more than 5 MPa after being lowered into the well.

It should be understood that in the present invention, the terms “first” and “second” are used for illustrative purposes only, and are not intended to indicate or imply relative importance or implicitly specify the number of technical features indicated. Thus, the technical features defined with the terms “first” or “second” may explicitly or implicitly include one or more such technical features. In the description of the present invention, “a plurality of” means two or more, unless otherwise specified.

In the present invention, unless otherwise specified or defined, the phrases “mount”, “connect”, “attach”, “fix” and the like, should be understood in a broad sense, and may be understood as, for example, fixed connections, detachable connections, or integral connections; mechanical or electrical connections; direct connections or indirect connections via intermediate structure; or interior communication between two elements. The specific meanings of the above phrases in the present invention can be understood by one skilled in the art in accordance with specific conditions.

The phrases “an embodiment”, “some embodiments”, “example”, “specific example” or “some examples” as mentioned in the description mean that the particular features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. Thus, the above illustrative phrases described throughout the description do not necessarily refer to the same embodiment or example. Moreover, the particular features, structures, materials, or characteristics described herein may be combined in any one or more of the embodiments or examples in a suitable manner.

Finally, it should be noted that the foregoing is only directed to preferred embodiments of the present invention, which does not constitute any limitations to the present invention. Although the present invention is described in detail with reference to the above embodiments, it is still possible for one skilled in the art to modify the technical solutions defined in the above embodiments or to replace some of the technical features with equivalent ones. Any modifications, equivalent substitutions, improvements or the like made within the spirit and principle of the present invention shall fall within the scope of protection of the present invention.

LIST OF REFERENCE SIGNS

• • 1. base tube; 101. first through hole;
  • 2. second insertion sleeve; 201. lower ring; 202. upper ring; 203. lug; 204. third flow channel hole; 205. third insertion groove; 206. fourth insertion groove; 207. second protective insertion groove; 208. communication groove;
  • 3. packing tube; 301. third through hole;
  • 4. conveying tube;
  • 5. packing groove; 501. arc-shaped groove plate; 502. arc-shaped bottom plate; 503. fourth through hole;
  • 6. sand filter; 601. flow-through channel;
  • 7. protective tube; 701. second through hole;
  • 8. first insertion sleeve; 801. first annular groove; 802. first insertion groove; 803. second insertion groove; 804. first flow channel hole; 805. first protective insertion groove; 806. first sealing groove; 807. first thread;
  • 9. spinning sleeve; 901. second thread; 902. rib;
  • 10. connection sleeve; 1001. second annular groove; 1002. second sealing groove; 1003. third sealing groove; 1004. second flow channel hole;
  • 11. bypass tube; 1101. wear-resistant plate; 1102. pad;
  • 12. first clamp; 1201. first arc-shaped groove; 1202. first hinge seat; 1203. first hinge hole; 1204. first flat shoulder; 1205. first pass-through hole; 1206. first hinge shaft; 1207. bolt; 1208. nut;
  • 13. second clamp; 1301. second arc-shaped groove; 1302. arc-shaped clamp; 1303. third arc-shaped groove; 1304. second hinge seat; 1305. second hinge hole; 1306. second flat shoulder; 1307. second pass-through hole; 1308. second hinge shaft;
  • 14. sealing gasket; 15. coupling; 16. spinning sealing ring; 17. base-tube sealing ring; 100. pack screen; 200. bypass connector.

Claims

1. A pack screen, comprising a base tube, a communication layer and a protective tube arranged in sequence from an inner side to an outer side thereof, wherein at least one first through hole is arranged on the base tube and at least one second through hole is arranged on the protective tube, the communication layer comprising a packing tube and a sand filter arranged in juxtaposition along a circumferential direction, wherein at least one third through hole is arranged on a wall of the packing tube and in fluid communication with the second through hole, so that fluid from the packing tube flows out of the pack screen through the third through hole and the second through hole; and

the sand filter is configured to cover the first through hole on the base tube, so that the fluid enters the base tube via the first through hole after flowing through the sand filter.

2. The pack screen according to claim 1, characterized in that a flow-through channel in communication with the third through hole is arranged between the protective tube and the base tube.

3. The pack screen according to claim 2, characterized in that the communication layer further comprises a conveying tube, wherein the conveying tube and the packing tube are spaced apart and alternately arranged between adjacent sand filters.

4. The pack screen according to claim 3, characterized in that one end of the flow-through channel is in communication with the third through hole on the packing tube, and another end thereof extends to a side wall of the conveying tube, wherein a side wall of the flow-through channel is in fluid communication with the second through hole.

5. The pack screen according to claim 4, characterized in that the flow-through channel is in a spiral shape, wherein an end of the flow-through channel close to the packing tube is higher than an end close to the conveying tube.

6. The pack screen according to claim 2, characterized in that a packing groove is arranged between the flow-through channel and the sand filter.

7. The pack screen according to claim 6, characterized in that the packing groove comprises:

an arc-shaped bottom plate in contact with the base tube;

arc-shaped groove plates arranged on both sides along a length direction of the arc-shaped bottom plate and configured to support the protective tube; and

a fourth through hole arranged at an end portion of the packing groove for communicating with the third through hole.

8. The pack screen according to claim 3, characterized in that cross sections of the packing tube and the conveying tube are each in a shape of a trapezoid, wherein a short side of the trapezoid fits a radian of the protective tube, while a long side thereof fits a radian of the base tube, the third through hole of the packing tube being provided on two waists of the trapezoid.

9. The pack screen according to claim 3, characterized in that a second insertion sleeve is provided at an upper portion of the base tube, wherein a lower end of the second insertion sleeve is connected to and in fluid communication with the packing tube and the conveying tube.

10. The pack screen according to claim 9, characterized in that a first insertion sleeve is provided at a lower portion of the base tube, an upper end of the first insertion sleeve being connected to the packing tube and the conveying tube, wherein a lower end of the packing tube is sealed by the first insertion sleeve, and the conveying tube is in fluid communication with the first insertion sleeve.

11. The pack screen according to claim 10, characterized in that insertion grooves are provided on the first insertion sleeve and the second insertion sleeve, for receiving the conveying tube, the packing tube and the protective tube, respectively.

12. A bypass connector for connecting two pack screens according to claim 10, comprising:

a coupling, for connecting the base tubes of the two pack screens;

a bypass tube arranged outside the base tube, wherein an upper end of the bypass tube is connected to the conveying tube of an upper, first pack screen through the first insertion sleeve thereof, and a lower end of the bypass tube is connected to the packing tube and the conveying tube of a lower, second pack screen through the second insertion sleeve thereof; and

a connection mechanism arranged between the second insertion sleeve of the second pack screen and the first insertion sleeve of the first pack screen, and configured to extend and contract along an axis direction, so that the bypass tube is inserted into the second insertion sleeve of the second pack screen and the first insertion sleeve of the first pack screen.

13. The bypass connector according to claim 12, characterized in that the connection mechanism is arranged between the bypass tube and the first insertion sleeve of the first pack screen, or between the bypass tube and the second insertion sleeve of the second pack screen.

14. The bypass connector according to claim 12, characterized in that the connection mechanism comprises:

a connection sleeve connected to the bypass tube; and

a spinning sleeve for connecting the first insertion sleeve and the connection sleeve, wherein the spinning sleeve is connected to the first insertion sleeve of the first pack screen through threads, axially connected to the connection sleeve through insertion in a sealed manner, and configured to adjust a length of the connection mechanism through circumferential rotation relative to the first insertion sleeve of the first pack screen, so that the bypass connector engages with the first pack screen and the second pack screen.

15. The bypass connector according to claim 12, characterized in that the bypass connector further comprises a clamp clamped outside the base tube, for fixedly connecting the bypass tube to the base tube and/or the coupling.

16. The bypass connector according to claim 12, characterized in that at least two wear-resistant plates are arranged on an outer side of the bypass tube along a length direction thereof.

17. The bypass connector according to claim 12, characterized in that at least two pads are arranged on an inner side of the bypass tube along the length direction thereof.