CN109707358B - Fracturing string and fracturing method thereof - Google Patents

Abstract

The invention discloses a fracturing pipe string and a fracturing method thereof. The fracturing pipe string includes: a casing string, multiple sets of intelligent ball-ball fracturing sliding sleeves and differential pressure sliding sleeves; Connected composition; multiple sets of intelligent ball-pitching fracturing sleeves, at least one set of the intelligent ball-pitching fracturing sleeves connected in series to the casing of each separation layer; differential pressure sliding sleeves, connected in series to the casing The lowest layer of the column.

Description

Fracturing string and fracturing method thereof

technical field

The invention relates to a fracturing pipe string and a fracturing method, in particular to a fracturing pipe string and a fracturing method used for large-diameter intelligent pitching of oil and gas exploitation equipment.

Background technique

In the process of oil and gas exploitation, fracturing operation is a very effective production stimulation method, especially layered stimulation technology has become an important means of production stimulation in low permeability oil and gas reservoirs, sliding sleeve segmental fracturing technology is the first choice for unconventional oil and gas resources exploitation. It is an important means, which is widely used in fracturing stimulation of vertical wells, directional wells, and horizontal wells in shale gas, low-permeability production layers, and thin oil layers.

Conventional sliding sleeves include ball sliding sleeves, hydraulic sliding sleeves and mechanical switch sliding sleeves.

The ball-throwing sliding sleeve is usually used in conjunction with the open hole packer. Its working principle is that the ball is thrown at the wellhead, and the ball reaches the ball seat of the sliding sleeve to form a seal with the ball seat of the sliding sleeve. When the pressing pressure reaches the set value, the pin is cut off, the sliding sleeve moves, and the fracturing through hole is exposed to establish a fracturing channel. However, the number of fracturing stages is limited due to the size difference between the sliding sleeves and balls at all levels, and after the fracturing is completed, a drilling tool needs to be lowered to drill the sliding sleeve ball seat, which increases the operating cycle and operating cost.

The hydraulic sliding sleeve is usually placed at the lowest stage of the staged fracturing string, and its working principle is to continue pressing after setting and sealing all the open hole packers. When the pressure reaches the opening pressure of the hydraulic sliding sleeve, the sliding sleeve is opened, and then the fracturing operation is carried out. The hydraulic sliding sleeve can only be used for one stage alone, and needs to be used in conjunction with the ball-pitching sliding sleeve to complete multi-stage fracturing.

The mechanical switch sleeve requires the switch tool to be lowered into the well together with the fracturing string. It is characterized in that it can be opened and closed by the switch tool, and there is no need to press the ball. Therefore, the performance and stability of the switch tool are high.

Therefore, it is urgent to develop a fracturing string and a fracturing method with an unlimited number of fracturing reservoirs.

Contents of the invention

The technical problem to be solved by the present invention is to provide a fracturing string, which includes:

The casing string is composed of multiple casings connected in series;

A plurality of sets of intelligent ball-pitching fracturing sleeves, each separation layer is connected with at least one set of said intelligent ball-pitching fracturing sleeves connected in series;

Differential pressure sliding sleeve, connected in series at the lowermost layer of the casing string

The above-mentioned fracturing string, wherein, each of the intelligent pitching fracturing sleeves includes an upper joint, a connecting sleeve, a sliding sleeve body and a lower joint connected in sequence, and the upper joint is connected to the upper joint of the casing At the bottom end, the lower joint is connected to the top of the casing at its lower part, and each of the smart ball fracturing sliding sleeves also includes:

A cylinder liner installed in the upper joint;

A hydraulic cylinder installed in the hydraulic cylinder sleeve;

an elastic body installed in the liquid cylinder;

The elastic sealing element is sheathed on the elastic body.

In the above-mentioned fracturing string, each of the smart ball fracturing sleeves further includes:

A transition sleeve is arranged in the upper joint, and one end of the transition sleeve is connected to the hydraulic cylinder;

The elastic piece is sheathed on the transition sleeve, one end of the elastic piece abuts against the transition sleeve, and the other end of the elastic piece abuts against the connecting sleeve.

The above-mentioned fracturing string, wherein, each of the fracturing sleeves further includes:

A track pipe, one part of which is located in the connecting sleeve, the other part of the track tube is located in the sliding sleeve, one end of the track tube is connected to the other end of the transition sleeve, wherein the hydraulic cylinder drives the The elastic body, the transition sleeve and the track tube move axially;

The swivel is sleeved on the track pipe and located between the connecting sleeve and the sliding sleeve body;

A guide pin penetrates through the swivel ring and is connected to the track pipe.

In the above-mentioned fracturing string, each of the fracturing sliding sleeves further includes an opening sleeve installed in the sliding sleeve body, and one end of the opening sleeve is spaced from the track pipe.

The above-mentioned fracturing string, wherein, the lower joint is connected to the sliding sleeve body, and the fracturing sliding sleeve further includes an elastic sealing seat, and the elastic sealing seat is installed between the opening sleeve and the lower joint , one end of the elastic sealing seat is connected to the lower joint, and the opening sleeve covers the elastic sealing seat after moving in the axial direction.

In the above-mentioned fracturing string, a plurality of long tracks and a plurality of short tracks are arranged on the outer wall of the track pipe along the circumferential direction, and the long tracks and the short tracks are arranged alternately and communicate with each other.

The above-mentioned fracturing string, wherein, the other end of the elastic sealing seat is provided with a plurality of claws.

In the above-mentioned fracturing string, a step limiting part is further provided on the inner wall of the sliding sleeve body, and the opening sleeve is arranged against the step limiting part.

The above-mentioned fracturing string, wherein, each of the fracturing sliding sleeves further includes a stopper structure installed on the inner wall of the sliding sleeve body, and when the opening sleeve moves in the axial direction, it covers the elastic seal Said opening sleeve is reversely moved by stopper behind the seat.

The above-mentioned fracturing string, which also includes:

A plurality of segmented packers are installed on the casing of each separated layer in one-to-one correspondence; and

The guide shoe is connected to the lowermost end of the fracturing string.

The above-mentioned fracturing string, which also includes:

bumper short joint, one end of which is connected to the differential pressure sliding sleeve;

a floating hoop, one end of which is connected to the lower end of said slam nipple; and

One end of the floating shoe is connected to the lower end of the floating hoop.

The present invention provides a fracturing method using the fracturing string described in any one of the foregoing, which also includes the following steps:

After determining the number of fracturing sleeves according to the actual situation of the reservoir, assemble the fracturing string;

Run the fracturing string into place according to the indication of the fracturing string table;

When the fracturing string is pressed to a set value, the differential pressure sliding sleeve is opened to establish a fluid channel with the reservoir;

After the fracturing of the bottom layer is completed, the fracturing balls are put in layer by layer, and the remaining target reservoirs are fractured.

The above-mentioned fracturing method, which also includes:

Each target reservoir corresponds to at least one of the smart ball fracturing sleeves;

Set each of the fracturing sleeves to open after the nth fracturing ball is in place, n is a positive integer;

When the nth frac ball is in place, the frac ball forms a seal in the bottommost frac sleeve of at least one of the frac sleeves;

Hydraulic fracturing is performed to open up the target reservoir.

The above-mentioned fracturing method, which also includes:

The cementing operation isolating the layer, after running the fracturing string in place, connect the cement injection pipeline, inject cement, and run the cementing plug to replace the cement slurry, and when the cementing plug runs to the bumping nipple, bumping Afterwards, the displacement is completed, the cement is waiting to set, and the cementing isolation layer is completed.

The above-mentioned fracturing method, which also includes:

Layered packers are layered, and each layer is isolated by two adjacent segmented packers on the casing. After the fracturing string is lowered in place, the fracturing The cracked pipe string is pressed, and each of the segmented packers is set to separate the layers of the target reservoir that need to be fractured.

The present invention is aimed at its effect of prior art and is:

1. Suitable for casing completion and open hole completion, not limited by well type, strong adaptability, and more choices for engineers;

2. Compared with the quick-drilling bridge plug technology, there is no need for pump plugs, perforating and drilling plugs, so that efficient fracturing can be achieved and fracturing costs can be reduced;

3. Compared with the conventional open hole packer combined with sliding sleeve technology, while ensuring the fracturing efficiency, the diameter does not become smaller, ensuring the integrity of the wellbore, and theoretically, the number of fracturing stages is not limited;

4. Intelligent ball counting, the engineer can set up many levels of counting according to the needs, one or more sliding sleeves can be opened at one time with one ball for the same level of counting, and fracturing can be freely matched according to needs;

5. Full diameter after fracturing, which is beneficial to subsequent production, workover, secondary fracturing and other operations, and prolongs the life of a single well.

Description of drawings

Fig. 1 is a structural schematic diagram of the first embodiment of the fracturing string of the present invention;

Fig. 2 is a structural schematic diagram of the practical fracturing sleeve;

Fig. 3 is a partial enlarged view of A in Fig. 2;

Fig. 4 is a partially enlarged view of B in Fig. 2;

Fig. 5 is a schematic diagram of the state of opening the cover when it is not working in Fig. 2;

Fig. 6 is a schematic diagram of the state of the fracturing ball passing through the opening sleeve during operation in Fig. 2;

Fig. 7 is a schematic diagram of the state of opening the sleeve during reverse row in Fig. 2;

Fig. 8 is a schematic structural view of the second embodiment of the fracturing string of the present invention;

Fig. 9 is a flowchart of the first embodiment of the fracturing method of the present invention;

Fig. 10 is the step-by-step flowchart of step S4 in Fig. 9;

Fig. 11 is a flow chart of the second embodiment of the fracturing method of the present invention.

Detailed ways

Herein, the detailed content and technical description of the present invention will be further described with a preferred embodiment, but it should not be construed as a limitation of the implementation of the present invention.

Please refer to Figures 1-4, Figure 1 is a schematic structural view of the first embodiment of the fracturing string of the present invention; Figure 2 is a structural schematic view of the practical fracturing sliding sleeve; Figure 3 is a partially enlarged view of A in Figure 1; 4 is a partial enlarged view of B in FIG. 2 . As shown in Figures 1-4, the fracturing string of the present invention includes a casing string, a plurality of intelligent ball-pitching fracturing sleeves Y and differential pressure sliding sleeves C; the casing string is composed of multiple casings M connected in series; each At least one set of intelligent ball-pitching fracturing sliding sleeves Y is connected in series between casings M separating layers G; the differential pressure sliding sleeve C is connected in series at the layer at the bottom of casing M.

The fracturing sliding sleeve of the present invention includes an upper joint 1, a connecting sleeve 9, a sliding sleeve body 10 and a lower joint 15 connected in sequence, and the fracturing sliding sleeve also includes: a hydraulic cylinder sleeve 2, a hydraulic cylinder 3, an elastic seal 4 and an elastic body 5. The upper joint 1 is connected to the lower end of the upper casing M, and the lower joint 15 is connected to the upper end of the lower casing string M. Each smart ball fracturing sliding sleeve also includes; the hydraulic cylinder sleeve 2 is installed on the upper Inside the joint 1; the liquid cylinder 3 is installed in the liquid cylinder sleeve 2; the elastic body 5 is installed in the liquid cylinder 3; the elastic seal 4 is set on the elastic body 5. Wherein, in this embodiment, the elastic body 5 is a metal elastic body, but the present invention is not limited thereto.

Further, the intelligent ball-ball fracturing sliding sleeve also includes: a transition sleeve 6 and an elastic member 7; the transition sleeve 6 is arranged in the upper joint 1, and one end of the transition sleeve 6 is connected to the hydraulic cylinder 3; the elastic member 7 is sleeved on the transition sleeve 6 Above, one end of the elastic member 7 abuts against the transition sleeve 6, and the other end of the elastic member 7 abuts against the connection sleeve 9, where the elastic member is a spring as a preferred embodiment, but the present invention is not limited thereto.

Furthermore, the smart ball-ball fracturing sliding sleeve also includes: a track tube 8, a swivel 11 and a guide pin 12; a part of the track tube 8 is located in the connecting sleeve 9, and the other part of the track tube 8 is located in the sliding sleeve body 10, and the track One end of the tube 8 is connected to the other end of the transition sleeve 6. After the ball is in place, the elastic body 5 hydraulically drives the hydraulic cylinder 3, so that the transition sleeve 6 and the track tube 8 move axially at the same time; the swivel 11 is sleeved on the track tube 8 and It is located between the connecting sleeve 9 and the sliding sleeve body 10 ; the guide pin 12 penetrates through the swivel 11 and is connected to the track pipe 8 . Wherein, a plurality of long tracks C1 and a plurality of short tracks C2 are arranged on the outer wall of the track tube 8 along the circumferential direction, and the long tracks C1 and the short tracks C2 are arranged alternately and communicate with each other.

Furthermore, the intelligent ball-ball fracturing sliding sleeve also includes an opening sleeve 13, an elastic sealing seat 14 and a stop structure 16, which are installed in the sliding sleeve body 10, and one end of the opening sleeve 13 is spaced from the other end of the track pipe 8; The joint 15 is connected with the sliding sleeve body 10, the elastic sealing seat 14 is installed between the opening sleeve 13 and the lower joint 15, one end of the elastic sealing seat 14 is connected to the lower joint 15, and the opening sleeve 13 can move axially to cover the elastic sealing seat 14; the other end of the elastic sealing seat 14 is provided with a plurality of claws 141, and the opening sleeve 13 is fastened to a plurality of claws 141; the upper ring of the inner wall of the sliding sleeve body 10 is provided with a step limiter 101, and the opening sleeve 13 reaches It is set by the step limiter 101; the stop structure 16 is installed on the inner wall of the sliding sleeve body 10, and when the opening sleeve 13 moves in the axial direction, it covers the elastic sealing seat 14 and then stops the reverse movement of the opening sleeve 13.

In this embodiment, the liquid cylinder 3, the elastic sealing member 4 and the elastic body 5 constitute a soft seal seat assembly; the soft seal seat assembly, the elastic member 7, and the track tube 8 (there are connected long track C1 and short track C2 outside the tube) , the swivel 11 and the guide pin 12 form an intelligent counting mechanism; the opening sleeve 13 and the elastic sealing seat 14 form a sliding sleeve mechanism; after the ball is thrown, the fracturing ball reaches the soft sealing seat assembly to form a temporary piston, and under the action of pressure, the force is transmitted to the track The pipe 8 and the track pipe 8 move once on the short track C2, the track pipe 8 drives the guide pin 12, the guide pin 12 drives the swivel 11 to rotate, and then the elastic member 7 drives the soft seal seat assembly to reset. Every time a fracturing ball is put in, it rotates once. When it rotates to the designated position, the track tube 8 enters the long track C1, and the track tube 8 transmits the force to the sliding sleeve mechanism to push the opening sleeve 13. After the opening sleeve 13 goes down, it will Moving to the elastic sealing seat 14, the inner diameter of the elastic sealing seat is forced to shrink, and the fracturing ball is seated here for sealing, and the fracturing operation can be carried out at this time. If the layer or adjacent layers need to throw a ball to open multiple sliding sleeves, then no elastic sealing seat is installed inside the front sliding sleeves in this layer or adjacent layers, only the last one The elastic sealing seat is installed on the sliding sleeve, and the ball can smoothly open the sliding sleeve and sit on the last sliding sleeve to carry out fracturing operations, and can press open one or more layers. Therefore, since the sliding sleeve can be set to open after putting in the Nth ball, and each stage can be installed with multiple sliding sleeves to open simultaneously, the fracturing sliding sleeve of the present invention is not limited by the number of fracturing layers; at the same time Since the sliding sleeves are opened by intelligent counting, because the inner diameter of each sliding sleeve can be the same, the maximum diameter of the sliding sleeves can be reserved without affecting the later work.

Furthermore, the fracturing string also includes: a plurality of segmented packers 17 and guide shoes 18; the plurality of segmented packers 17 are installed on the casing M of each separated layer G in one-to-one correspondence , each interval G is separated by two adjacent segmented packers 17 on the casing M; the guide shoe 18 is connected to the differential pressure sliding sleeve C.

Please refer to Figure 5-7, Figure 5 is a schematic diagram of the state of opening the sleeve when it is not working in Figure 2; Figure 6 is a schematic diagram of the state of the fracturing ball passing through the opening sleeve when it is working in Figure 2; Figure 7 is a schematic diagram of the state of the ball when it is reversed in Figure 8 The schematic diagram of the state of opening the sliding sleeve moved to the upper level, and the working process of the fracturing string and the fracturing sliding sleeve of the present invention will be described in detail below in conjunction with Figures 1-7. It should be noted that the specific numerical values described below are only for illustrating the working process of the present invention, and the present invention is not limited thereto.

According to the actual situation of the reservoir and the fracturing design, determine the position and quantity of the fracturing sleeve Y and the position and quantity of the differential pressure sleeve C on the fracturing string, and run the fracturing string according to the fracturing string table in place. In this fracturing string, the differential pressure sliding sleeve C is the sliding sleeve installed at the bottom end. By pressing the fracturing string to the set value, the differential pressure sliding sleeve C is opened for fracturing construction. Sleeve C is used to open the reservoir and establish fluid pathways. The intelligent ball-pitching fracturing sleeve Y is used for fracturing operations after the ball-pitching fracturing sleeve is opened. Since the segmented packer 17 is set, no cementing operation is required.

The fracturing operation is carried out according to the fracturing design. Firstly, the fracturing string is pressed, and the segmental packers 17 of the entire fracturing string are set to separate the layers to be fractured. After the staged packer 17 is set, the pressure continues to increase, and the bottom differential pressure sliding sleeve C is opened to carry out fracturing operations at the bottom layer to establish fluid channels. Then throw the fracturing balls. Since the flow path has been established with the reservoir, the fracturing balls can be pumped into place during horizontal well operations. Every time the fracturing ball passes through a smart ball fracturing sliding sleeve Y, the fracturing sliding sleeve Y counts. When the Nth ball set by the smart ball fracturing sleeve Y is in place, the smart ball fracturing sleeve Y is opened, the ball will not pass through the sleeve, and the ball seat in the smart ball fracturing sleeve Y The hydraulic fracturing operation can be carried out, and the fracturing ball stays on the sealing seat of the intelligent ball fracturing sliding sleeve Y. If there are X smart ball-pitching fracturing sleeves Y corresponding to a certain layer or multiple adjacent layers, all of which are set after the N fracturing ball is in place, the fracturing ball can pass through all the previous fracturing sleeves Y, And a seal is formed on the bottommost intelligent ball fracturing sliding sleeve Y. When hydraulic fracturing is performed, the X sliding sleeves on this layer or adjacent multiple layers are hydraulically pressed open, and the fracturing balls always stay On the smart ball fracturing sliding sleeve Y at the bottom of this layer. According to the fracturing design requirements, perform fracturing operations in other layers. Since each intelligent ball-dropping fracturing sleeve Y can be designed to open after passing the Nth ball, and each time X number of sliding sleeves can be opened, the number of intelligent ball-dropping fracturing sleeves Y can fully satisfy the entire fracturing sleeve Y. The requirements for the design of the fracture string are not limited by the size and length of the fracturing string, and the maximum diameter is maintained without affecting the later operation.

Among them, the specific working process of the intelligent ball fracturing sleeve Y is as follows:

The minimum channel flexible inner diameter of the frac sleeve when not pitching is 110mm and the rigid inner diameter is 118mm. When the fracturing ball is put into operation, when the fracturing ball reaches the inner diameter of the soft sealing ring of 110mm, the fracturing ball is temporarily blocked by the metal elastic body 5, and the pressure is suppressed, and the track tube 8 is under the action of the metal elastic body 5 and the liquid cylinder 3 shift. When the pressure difference exceeds 3MPa, the fracturing ball passes through the metal elastic body 5 and passes through the elastic sealing seat 14 . Track pipe 8 returns to counting position under the effect of spring. When the fracturing ball is pitched for the Nth time and the pressure is suppressed, the intelligent counter (not shown) reaches the set value, and several guide pins 12 enter the long track of the track tube 8 at the same time, so that the track tube 8 can move a long distance to push open Cover 13 moves down, and the fracturing hole is opened. Open the lower end of the sleeve 13 to cover the elastic sealing seat 14, forcing the elastic grip of the elastic sealing seat 14 to shrink and become rigid. When the pressure difference exceeds 3MPa, the fracturing ball passes through the metal elastic body 5 and falls on the elastic sealing seat 14, fracturing The ball is sealed with the elastic sealing seat 14. At this time, pressure can be used to open one or more sliding sleeves of the same count (multiple sliding sleeves are all set to open after passing through the N ball, except that the last sliding sleeve is equipped with a hard seal seat 14, and the first few sliding sleeves are not equipped with elastic seals. Seat 14 does not affect the opening sleeve 13 being opened, the ball passes through smoothly and sits on the sliding sleeve at the bottom), holds back the formation, and when the fracturing ball is suppressed by the elastic sealing seat 14, the opening sleeve 13 is always under the pressure difference is low. When all layers are fractured and the wellhead is decompressed and the formation is reversed, the ball moves to the bottom of the elastic sealing seat 14 of the previous sliding sleeve. After the opening sleeve 13 moves up for a certain distance under the action of downward pressure, the stop mechanism 16 stops the opening sleeve. 13. The elastic sealing seat (14) is opened, and the fracturing ball passes upward through the elastic sealing seat 14 and the metal elastic body 5, and is reversely discharged to the wellhead to be captured by a ball catcher (not shown).

Wherein, when the fracturing ball reaches the flexible inner diameter of the metal elastic body 5, the fracturing ball is temporarily blocked, and when a certain pressure is applied to the upper end of the fracturing ball, the fracturing ball can pass through the metal elastic body 5. Therefore, the pressure of the ball passing through the metal elastic body 5 can be changed by adjusting the metal elastic body 5 and the elastic sealing member 4 . When the fracturing ball reaches the flexible inner diameter of the metal elastic body 5, before the fracturing ball passes through the metal elastic body 5, the metal elastic body 5, the elastic seal 4 and the fracturing ball form a temporary piston, and the hydraulic cylinder 3 can provide a shaft when the pressure is suppressed. thrust, but when the frac ball passes, the piston effect disappears.

The outer wall of the track tube 8 is provided with a plurality of long tracks C1 and a plurality of short tracks C2 along the circumferential direction. The long tracks C1 and the short tracks C2 are alternately arranged and communicated with each other. The multiple long tracks C1, the multiple short tracks C2, the swivel 11 and guide pin 12 form counter jointly, and wherein swivel 11 and guide pin 12 work on the groove of track tube 8, open ball seat after setting counter N balls before going down well. The working ball reaches the metal elastic body 5 to suppress pressure, and the temporary piston provides axial thrust. When the orbital tube 8 moves axially, under the action of the guide pin 12 and the swivel 11, the swivel 11 is forced to turn through a certain angle. The thrust provided by the temporary piston is limited by the short track C2, and cannot directly act on the opening sleeve 13, and the opening sleeve 13 cannot be opened. After the fracturing ball passes through the metal elastic body 5, the axial thrust provided by the hydraulic cylinder 3 disappears, and the track tube 8 returns to the counting position under the action of the spring. After throwing N balls, when the counter returns to No. 0 position, the temporary piston works in the long track C1, and the thrust provided by the hydraulic cylinder 3 can act on the opening cover 13, and the opening cover 13 is opened.

Please refer to FIG. 8 , which is a schematic structural diagram of a second embodiment of the fracturing string of the present invention. As shown in Fig. 8, the fracturing string includes a casing string, multiple smart ball fracturing sleeves Y and differential pressure sleeves C; the casing string is composed of multiple casings M connected in series; each separated Each layer is connected with at least one intelligent ball-pitching fracturing sleeve Y connected in series; the differential pressure sleeve C is connected in series with the layer at the bottom of the casing string; the difference from Figure 1 is that the fracturing string in this embodiment Since the sub-section packer 17 and guide shoe 18 are not set, the bump nipple 19, the floating hoop 20 and the float shoe 21 are added; one end of the bump nipple 19 is connected to the differential pressure sliding sleeve C; the floating hoop 20 One end is connected to the other end of the ram short joint 19; one end of the floating shoe 21 is connected to the other end of the floating hoop 20. According to the structure of this embodiment, after the fracturing string is run in, the cementing and layering operations are carried out, the cementing pipeline is connected, the cement 22 is injected, and the cementing plug is run in to replace the cement 22. After bumping and pressing in section 19, the displacement is completed, and the cement 22 is waited for solidification, and the cementing layering operation is completed. The rest of the working process of this embodiment is the same as the working process of FIG. 1 and will not be repeated here.

Please refer to Figures 9-10, Figure 9 is a flow chart of the first embodiment of the fracturing method of the present invention; Figure 10 is a step-by-step flow chart of step S5 in Figure 9 . As shown in Figures 9-10, the fracturing method of the present invention includes:

S1: After determining the layers that need to be fractured and the number of fracturing sleeves according to the actual situation of the reservoir, assemble the fracturing string;

S2: Run the fracturing string into place according to the indication of the fracturing string table;

S3: After running in place, pressurize the fracturing string, set each segmented packer, separate the layers of the target reservoir to be fractured, and complete the interlayer isolation;

S4: When the fracturing string is pressed to a set value, the differential pressure sliding sleeve is opened to establish a fluid channel with the reservoir;

S5: After the fracturing of the bottom layer is completed, the fracturing balls are put in layer by layer, and the remaining target reservoirs are fractured.

Further, step S5 also includes:

S51: Each target reservoir corresponds to at least one smart ball fracturing sleeve;

S52: Set each of the intelligent pitching fracturing sleeves to open after the nth fracturing ball is in place, where n is a positive integer;

S53: When the nth fracturing ball is in place, the fracturing ball forms a seal in the bottommost fracturing sleeve of at least one smart ball fracturing sleeve;

S54: Perform hydraulic fracturing to open the target reservoir.

Please refer to FIG. 11 , which is a flow chart of the second embodiment of the fracturing method of the present invention. As shown in Figure 11, the fracturing method of the present invention includes:

S1': After determining the layers that need to be fractured and the number of fracturing sleeves according to the actual situation of the reservoir, assemble the fracturing string;

S2': Run the fracturing string into place according to the indication of the fracturing string table;

S3': After running in place, connect the cement injection pipeline, inject cement, and run the cementing plug to replace the cement slurry. When the cementing plug runs to the bumper nipple for bumping, the replacement is completed, and the cement is waiting to set. The cementing operation is completed layer by layer, and the layer isolation is completed;

S4': When the fracturing string is pressed to a set value, the differential pressure sliding sleeve is opened to establish a fluid channel with the reservoir;

S5': After the fracturing of the bottom layer is completed, the fracturing balls are put in layer by layer, and the remaining target reservoirs are fractured. Wherein step S5' is the same as the aforementioned step S5, so it will not be repeated here.

It is worth noting that in this embodiment, since the cementing operation is performed in layers, the setting of segmental packers can be omitted.

In summary, the present invention has the following advantages:

1. Suitable for casing completion and open hole completion, not limited by well type, strong adaptability, and more choices for engineers;

2. Compared with the quick-drilling bridge plug technology, there is no need for pump plugs, perforating and drilling plugs, so that efficient fracturing can be achieved and fracturing costs can be reduced;

3. Compared with the conventional open hole packer combined with the sliding sleeve technology, the fracturing efficiency is ensured, while the diameter is not reduced, the integrity of the wellbore is guaranteed, and the number of fracturing stages is not limited;

4. Intelligent ball counting, the engineer can set up many levels of counting according to the needs, one or more sliding sleeves can be opened at one time with one ball for the same level of counting, and fracturing can be freely matched according to needs;

5. Full diameter after fracturing, which is beneficial to subsequent production, workover, secondary fracturing and other operations, and prolongs the life of a single well.

The above are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding adjustments according to the present invention. Changes and deformations, but these corresponding changes and deformations should fall within the scope of protection of the appended claims of the present invention.

Claims (10)

1. A fracturing string comprising:

the casing string is formed by connecting a plurality of casing pipes in series;

the intelligent ball-throwing fracturing sliding sleeves are connected in series, and at least one intelligent ball-throwing fracturing sliding sleeve is connected to the sleeve of each separation layer;

the differential pressure sliding sleeve is connected in series with the lowest layer of the casing string;

the segmented packers are arranged on the casing pipe of each separation layer in a one-to-one correspondence manner; and

The guide shoe is connected to the lowest end of the fracturing string;

each intelligent ball-throwing fracturing sliding sleeve comprises an upper joint, a connecting sleeve, a sliding sleeve body and a lower joint which are sequentially connected, wherein the upper joint is connected to the bottom end of the sleeve on the upper part of the sliding sleeve, the lower joint is connected to the top end of the sleeve on the lower part of the sliding sleeve, and each intelligent ball-throwing fracturing sliding sleeve further comprises:

the liquid cylinder sleeve is arranged in the upper joint;

the hydraulic cylinder is arranged in the hydraulic cylinder sleeve;

the elastic body is arranged in the hydraulic cylinder;

the elastic sealing piece is sleeved on the elastic body;

the transition sleeve is arranged in the upper joint, and one end of the transition sleeve is connected with the hydraulic cylinder;

the elastic piece is sleeved on the transition sleeve, one end of the elastic piece abuts against the transition sleeve, and the other end of the elastic piece abuts against the connecting sleeve;

the track pipe is positioned in the connecting sleeve, the other part of the track pipe is positioned in the sliding sleeve, one end of the track pipe is connected with the other end of the transition sleeve, and the hydraulic cylinder drives the elastic body, the transition sleeve and the track pipe to move along the axial direction;

the swivel is sleeved on the track pipe and positioned between the connecting sleeve and the sliding sleeve body;

the guide pin penetrates through the swivel and is connected to the track pipe; and

the opening sleeve is arranged in the sliding sleeve body, and one end of the opening sleeve is spaced from the track pipe;

the lower joint is connected with the sliding sleeve body, the fracturing sliding sleeve further comprises an elastic sealing seat, the elastic sealing seat is arranged between the opening sleeve and the lower joint, one end of the elastic sealing seat is connected with the lower joint, and the opening sleeve is sleeved on the elastic sealing seat after moving axially.

2. The fracturing string of claim 1, wherein a plurality of long tracks and a plurality of short tracks are formed on the outer wall of the track pipe along the circumferential direction, and the long tracks and the short tracks are alternately arranged and communicated with each other.

3. The fracturing string of claim 1, wherein the other end of the resilient seal seat is provided with a plurality of jaws.

4. The fracturing string of claim 1, wherein the inner wall of the sliding sleeve body is further provided with a step limiting portion, and the opening sleeve is arranged against the step limiting portion.

5. The fracturing string of claim 1, wherein each said fracturing slide sleeve further comprises a stop structure mounted to an inner wall of said slide sleeve body for stopping reverse movement of said open sleeve after said open sleeve is axially moved to engage said elastomeric seal seat.

6. The fracturing string as recited in claim 1, further comprising:

one end of the touch-pressing nipple is connected with the differential pressure sliding sleeve;

one end of the floating hoop is connected to the lower end of the collision-pressing short section; and

And one end of the floating shoe is connected with the lower end of the floating hoop.

7. A fracturing method using the fracturing string of any of claims 1-6, comprising the steps of:

after the number of the fracturing sliding sleeves is determined according to the actual condition of the oil reservoir, the fracturing tubular column is assembled;

according to the indication of the fracturing string table, the fracturing string is put into place;

opening a differential pressure sliding sleeve when the fracturing string is pressed to a set value, and establishing a fluid channel with a reservoir;

and after the bottom layer fracturing is finished, putting fracturing balls layer by layer, and fracturing the rest target reservoirs.

8. The fracturing method of claim 7, further comprising:

each target reservoir corresponds to at least one intelligent ball-throwing fracturing sliding sleeve;

setting each intelligent ball-throwing fracturing sliding sleeve as an nth fracturing ball to be opened after being in place, wherein n is a positive integer;

when the nth fracturing ball is in place, the fracturing ball forms a seal in the bottommost fracturing sliding sleeve in at least one intelligent ball-throwing fracturing sliding sleeve;

and carrying out hydraulic fracturing and opening the target reservoir.

9. The fracturing method of claim 8, further comprising:

and (3) connecting a cementing pipeline after the fracturing string is put in place, injecting cement, putting a cementing rubber plug into the well to replace cement paste, and after the cementing rubber plug runs to a collision and pressure nipple for collision and pressure, completing the replacement, waiting for cement setting, and completing the well cementation isolation layering.

10. The fracturing method of claim 8, further comprising:

and layering by using layered packers, wherein each layer is formed by isolating two adjacent segmented packers on the casing, pressing the fracturing string after the fracturing string is put in place, setting each segmented packer, and separating the layers of the target reservoir to be fractured.