Fracturing, draining and testing integrated tubular column and construction method thereof

Abstract

The invention relates to the technical field of petroleum and natural gas reservoir testing, in particular to a fracturing and drainage testing integrated tubular column and a construction method thereof, and aims to solve the technical problem that an existing fracturing and drainage integrated tubular column cannot perform formation testing on a reservoir before and after fracturing. The circulating channel on the pump seat of the fracturing, liquid discharging and testing integrated tubular column can be repeatedly opened and closed, the liquid discharging test of the jet pump can be carried out when the circulating channel is opened, fracturing operation can be carried out after the circulating channel is closed, formation tests before and after fracturing can be achieved without moving the tubular column, and the fracturing effect is objectively evaluated through comparison of test data before and after fracturing.

Description

Technical Field

[0001] The invention relates to the technical field of petroleum and natural gas reservoir testing, and in particular to an integrated pipe string for fracturing and drainage testing and a construction method thereof. Background Art

[0002] At present, the reservoir transformation of oil and gas wells mainly adopts the sand fracturing process, the purpose of which is to form cracks in the formation and fill them with sand to support them, so that the reservoir has better permeability, thereby increasing oil and gas production.

[0003] At present, the commonly used integrated fracturing and drainage strings mainly include: tubing + fracturing packer, tubing + jet pump seat + fracturing packer and tubing + jet pump seat + full-bore selection test valve + eccentric voltage support + fracturing packer. After fracturing, the fluid is discharged through the continuous tubing or the jet pump is put into use for drainage. However, the existing integrated fracturing and drainage strings cannot test the reservoir before and after fracturing, so it is impossible to make an objective and timely evaluation of the fracturing effect. Summary of the invention

[0004] The purpose of the present invention is to provide an integrated fracturing and drainage testing pipe string and a construction method thereof, so as to solve the technical problem that the existing integrated fracturing and drainage pipe string cannot perform formation testing on the reservoir before and after fracturing.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] In a first aspect, the present invention provides an integrated pipe string for fracturing and drainage testing, comprising: an oil pipe, a pump seat, a pump core and a pressure gauge;

[0007] The pump seat is arranged at one end of the oil pipe, and comprises an outer sleeve, a center pipe and a circulation control assembly;

[0008] The outer sleeve is sleeved on the central tube and is threadedly connected to the central tube, and a flow passage is formed between the outer sleeve and the central tube;

[0009] The outer sleeve is provided with a first circulation hole penetrating through the side wall thereof, and the first circulation hole is communicated with the flow passage;

[0010] The central tube is provided with a second circulation hole penetrating through its side wall, and the second circulation hole is also connected to the flow passage;

[0011] The circulation control component is arranged in the flow passage, and is used to control the on-off of the flow passage between the second circulation hole and the first circulation hole;

[0012] The pump core is used to be mounted on the inner wall of the central tube and has a drainage hole, and the drainage hole can be connected with the second circulation hole in the mounted working state;

[0013] The pressure gauge is connected to the pump core.

[0014] Further, the circulation control assembly includes an upper shift fork, a float valve and a lower shift fork, and the upper shift fork, the float valve and the lower shift fork are sequentially distributed from the threaded connection between the outer sleeve and the central tube to a direction away from the threaded connection;

[0015] The upper shift fork is arranged on the inner wall of the outer sleeve, and the end surface opposite to the float valve is provided with a plurality of first short saw teeth extending along the respective circumferential directions;

[0016] The float valve can slide along the axial direction of the flow passage to block or conduct the flow passage between the second circulation hole and the first circulation hole, and two symmetrically distributed long saw teeth are provided on the end surface of the float valve opposite to the lower fork;

[0017] The lower shift fork is arranged on the inner wall of the outer sleeve, and two second short saw teeth and a plurality of third short saw teeth extending along its circumference and used to engage with the long saw teeth are provided on the end surface opposite to the float valve, wherein the two second short saw teeth are symmetrically distributed about the axis of the lower shift fork, and the plurality of third short saw teeth are flush with each other and higher than the second short saw teeth.

[0018] Furthermore, a first sealing ring and a second sealing ring are respectively embedded inside and outside the float valve;

[0019] The first sealing ring abuts between the float valve and the central tube;

[0020] The second sealing ring abuts between the float valve and the outer sleeve.

[0021] Furthermore, the pump core includes a nozzle, a diffuser, an outer cylinder and a flow nipple;

[0022] The diffuser is provided with a primary flow channel and a secondary flow channel which are spaced apart from each other, and both the primary flow channel and the secondary flow channel are connected to the nozzle;

[0023] The outer cylinder is sleeved on the diffuser and forms a flow annular cavity between the outer cylinder and the diffuser that is connected to the secondary flow channel;

[0024] The flow nipple is threadedly connected to the outer cylinder and the diffuser pipe, and the flow nipple is provided with a main channel, one end of the main channel is connected to the main channel, and the other end is closed;

[0025] Along the axial direction of the flow short section, a side channel spaced apart from the main channel is provided on the side wall of the flow short section, and the side channel is communicated with the flow annular cavity;

[0026] The flow nipple is provided with the drainage hole penetrating through the side wall thereof, and the drainage hole is communicated with the main pore.

[0027] Furthermore, the flow sub is further provided with a blind cavity, and in the axial direction of the flow sub, the blind cavity is spaced apart from the main channel;

[0028] The side channel extends from the flow ring cavity to communicate with the blind cavity;

[0029] The pump core also includes a lower joint and a shut-in valve;

[0030] The lower joint is threadedly connected to the flow nipple and communicates with the blind cavity;

[0031] The shut-in valve is arranged in the blind cavity and is located in the space enclosed by the lower joint and the flow nipple, and is used to block or conduct the lower joint to correspondingly block or establish the communication between the lower joint and the side channel.

[0032] Furthermore, a third sealing ring and a fourth sealing ring are respectively embedded outside the flow nipple and outside the lower joint;

[0033] In the axial direction of the flow nipple, the third sealing ring and the fourth sealing ring are distributed on both sides of the drainage hole, and can abut against the inner wall of the central tube in the sitting and hanging condition.

[0034] Furthermore, the inner wall of the central tube is provided with a step, and the flow nipple abuts against the step surface.

[0035] Furthermore, the pump core also includes a leather cup shaft, a leather cup, a leather cup seat, a fishing head and a filter screen;

[0036] The leather cup shaft sleeve is arranged on the nozzle and is threadedly connected to the nozzle, and is also threadedly connected to the end of the outer cylinder away from the flow nipple;

[0037] The leather cup is sleeved on the leather cup shaft;

[0038] The leather cup seat is connected between the leather cup shaft and the fishing head and abuts against the leather cup, and a check valve is arranged in the leather cup seat;

[0039] The fishing head is provided with a flow hole penetrating through the side wall thereof, and the filter screen is arranged on the side wall of the fishing head and blocks the flow hole.

[0040] Furthermore, the integrated fracturing and drainage test string also includes a sand support, a spacer tubing, a fracturing packer and a full-bore pressure gauge support tube which are sequentially distributed along the axial direction of the tubing;

[0041] The sand supporter is connected to the pump seat, the spacer oil pipe is connected between the sand supporter and the fracturing packer, and the full-bore pressure gauge support tube is connected to the fracturing packer.

[0042] In a second aspect, the present invention further provides a method for constructing an integrated pipe string for fracturing and drainage testing. The method is based on the above-mentioned integrated pipe string for fracturing and drainage testing, and comprises the following steps:

[0043] S100: Pre-fracture test:

[0044] S110: Lower the integrated fracturing and drainage test string to the predetermined position in the well, then seal the fracturing packer, install the tubing hanger, tubing tee or Christmas tree at the wellhead, and connect the surface injection system;

[0045] S120: Open the circulation channel on the pump seat by hydraulic means, then put the pump core connected to the pressure gauge into the oil pipe, pump it to the pump seat, and then pump pressure to the pump core;

[0046] S130: After multiple discharges, reverse circulation is performed to remove the pump core and pressure gauge;

[0047] S200: After the pump core is removed, the circulation channel on the pump seat is closed through a large displacement positive circulation method, and then the fracturing operation is carried out;

[0048] S300: After the fracturing operation is completed, the circulation channel on the pump seat is opened hydraulically and the pump core is put into operation again. After multiple drainages, the pump core and the pressure gauge are removed again.

[0049] In summary of the above technical solutions, the technical effects that can be achieved by the integrated fracturing and drainage testing string provided by the present invention are:

[0050] In the integrated tubing string for fracturing and drainage testing, the circulation control component can control the connection or disconnection of the first circulation hole and the second circulation hole by controlling the opening and closing of the flow channel between the second circulation hole and the first circulation hole, that is, the circulation channel of the pump seat is opened or closed; when the pump core is hung on the central pipe, if the first circulation hole is connected with the second circulation hole, the liquid in the pump core will enter the circulation channel through the drainage hole and then be discharged from the pump seat; if the first circulation hole is disconnected from the second circulation hole, the liquid in the pump core will be blocked when flowing to the second circulation hole and cannot be discharged from the pump seat.

[0051] In specific applications, the circulation channel of the pump seat is set to the open state, and then the designed integrated pipe string for fracturing and drainage test is lowered to the predetermined position underground. After it is installed, the pump core is pumped into the pump seat and hung with the pump seat; the pressure is continued to be increased, the formation fluid will be sucked into the pump core, and then flow to the drainage hole with the power fluid, and enter the oil casing annulus through the circulation channel and return to the ground. This is the initial flow; after a period of drainage, the pump is stopped, and the formation fluid is no longer sucked. This is the initial well shut-in; after a period of initial shut-in, the oil casing annulus is opened first, and the pump pressure is pumped again for drainage. This is the secondary flow; after the secondary flow is completed, the pump is stopped again, and the secondary well is shut-in. This is repeated many times to achieve multiple underground well openings and closings. During the above process, the pressure gauge will record the pressure and temperature changes at every moment during the construction process. This is the pre-fracturing test. After the test is completed, the pump core and the pressure gauge are pulled out by reverse circulation, and the pre-fracturing test can be explained by replaying the pressure gauge data.

[0052] After the pre-fracturing test is completed, the circulation control component controls the circulation channel to be closed, and then the formation is subjected to fracturing. After the fracturing operation is completed, the circulation control component controls the circulation channel to be opened, and the pump core is put into operation again for multiple downhole opening and closing, and then the pump core and the pressure gauge are pulled out again by reverse circulation, and the pressure gauge data can be played back to interpret the post-fracturing test.

[0053] It can be seen that compared with the existing technology, the circulation channel on the pump seat of the integrated fracturing and drainage test string can be opened and closed repeatedly. When opened, the jet pump drainage test can be carried out, and when closed, the fracturing operation can be carried out. The formation test before and after fracturing can be realized without moving the string, and the fracturing effect can be objectively evaluated by comparing the test data before and after fracturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0055] Figure 1 A cross-sectional view of an integrated pipe string for fracturing and drainage testing provided by an embodiment of the present invention;

[0056] Figure 2 A cross-sectional view of a pump seat provided by an embodiment of the present invention;

[0057] Figure 3 A cross-sectional view of a circulation control assembly provided by an embodiment of the present invention;

[0058] Figure 4 A cross-sectional view of a pump core provided in accordance with an embodiment of the present invention.

[0059] Icons: 1-oil pipe; 2-flange; 3-outer sleeve; 4-center pipe; 5-flow channel; 6-first circulation hole; 7-second circulation hole; 8-drain hole; 9-upper fork; 10-float valve; 11-lower fork; 12-first short sawtooth; 13-long sawtooth; 14-second short sawtooth; 15-third short sawtooth; 16-first sealing ring; 17-second sealing ring; 18-nozzle; 19-diffuser; 20-outer cylinder; 21-flow short section; 22-main flow channel; 23-secondary flow channel; 24-flow ring cavity; 25-main channel; 26 - side channel; 27 - blind cavity; 28 - lower joint; 29 - shut-in valve; 30 - third sealing ring; 31 - fourth sealing ring; 32 - step; 33 - leather cup shaft; 34 - leather cup; 35 - leather cup seat; 36 - fishing head; 37 - filter screen; 38 - sand supporter; 39 - interval tubing; 40 - fracturing packer; 41 - full-bore pressure gauge support; 42 - connector; 43 - plug; 44 - tubing tee; 45 - catcher; 46 - tubing hanger; 47 - casing; 48 - casing tee; 49 - fifth sealing ring; 50 - check valve. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0061] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0062] Some embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments can be combined with each other.

[0063] At present, the commonly used integrated fracturing and drainage strings mainly include: tubing + fracturing packer, tubing + jet pump seat + fracturing packer and tubing + jet pump seat + full-bore selection test valve + eccentric voltage support + fracturing packer. After fracturing, the fluid is discharged through the continuous tubing or the jet pump is put into use for drainage. However, the existing integrated fracturing and drainage strings cannot test the reservoir before and after fracturing, so it is impossible to make an objective and timely evaluation of the fracturing effect.

[0064] In view of this, the present invention provides an integrated fracturing drainage test string, including an oil pipe 1, a pump seat, a pump core and a pressure gauge; the pump seat is arranged at one end of the oil pipe 1, including an outer sleeve 3, a central pipe 4 and a circulation control component; the outer sleeve 3 is sleeved on the central pipe 4 and is threadedly connected to the central pipe 4, and a flow channel 5 is formed between the outer sleeve 3 and the central pipe 4; the outer sleeve 3 is provided with a first circulation hole 6 penetrating its side wall, and the first circulation hole 6 is connected to the flow channel 5; the central pipe 4 is provided with a second circulation hole 7 penetrating its side wall, and the second circulation hole 7 is also connected to the flow channel 5; the circulation control component is arranged in the flow channel 5, for controlling the on-off of the flow channel 5 between the second circulation hole 7 and the first circulation hole 6; the pump core is used to sit on the inner wall of the central pipe 4, and has a drainage hole 8, and the drainage hole 8 can be connected to the second circulation hole 7 under the sitting condition; the pressure gauge is connected to the pump core.

[0065] In the integrated tubing string for fracturing and drainage testing, the circulation control component can control the connection or disconnection of the first circulation hole 6 and the second circulation hole 7 by controlling the on-off of the flow channel 5 between the second circulation hole 7 and the first circulation hole 6, that is, the circulation channel of the pump seat is opened or closed; when the pump core is hung on the central pipe 4, if the first circulation hole 6 is connected with the second circulation hole 7, the liquid in the pump core will enter the circulation channel through the drainage hole 8 and then be discharged from the pump seat; if the first circulation hole 6 is disconnected from the second circulation hole 7, the liquid in the pump core will be blocked when flowing to the second circulation hole 7 and cannot be discharged from the pump seat.

[0066] In specific applications, the circulation channel of the pump seat is set to the open state, and then the designed integrated pipe string for fracturing and drainage test is lowered to the predetermined position underground. After it is installed, the pump core is pumped into the pump seat and hung with the pump seat; the pressure is continued to be increased, and the formation fluid will be sucked into the pump core, and then flow to the drainage hole 8 with the power fluid, and enter the oil casing annulus through the circulation channel and return to the ground. This is the initial flow; after a period of auxiliary drainage, the pump is stopped, and the formation fluid is no longer sucked. This is the initial well closure; after a period of initial closure, the oil casing annulus is opened first, and the pump pressure is pumped again for drainage. This is the secondary flow; after the secondary flow is completed, the pump is stopped again, and the secondary well is shut down. This is repeated many times to achieve multiple underground well openings and closings. During the above process, the pressure gauge will record the pressure and temperature changes at every moment during the construction process. This is the pre-fracturing test. After the test is completed, the pump core and the pressure gauge are reversely circulated to pull out, and the pressure gauge data can be played back to explain the pre-fracturing test.

[0067] After the pre-fracturing test is completed, the circulation control component controls the circulation channel to be closed, and then the formation is subjected to fracturing. After the fracturing operation is completed, the circulation control component controls the circulation channel to be opened, and the pump core is put into operation again for multiple downhole opening and closing, and then the pump core and the pressure gauge are pulled out again by reverse circulation, and the pressure gauge data can be played back to interpret the post-fracturing test.

[0068] It can be seen that compared with the existing technology, the circulation channel on the pump seat of the integrated fracturing and drainage test string can be opened and closed repeatedly. When opened, the jet pump drainage test can be carried out, and when closed, the fracturing operation can be carried out. The formation test before and after fracturing can be realized without moving the string, and the fracturing effect can be objectively evaluated by comparing the test data before and after fracturing.

[0069] The following combination Figures 1 to 4 The structure and shape of the integrated pipe string for fracturing and drainage testing provided in this embodiment are described in detail:

[0070] refer to Figure 1 The integrated fracturing and drainage test string also includes a sand holder 38, a spacer oil pipe 39, a fracturing packer 40 and a full-bore pressure gauge holder 41 which are sequentially distributed along the axial direction of the oil pipe 1; a connector 42 is threadedly connected to the lower end of the outer sleeve 3, and the connector 42 is connected to the sand holder 38; the spacer oil pipe 39 is connected between the sand holder 38 and the fracturing packer 40, and the full-bore pressure gauge holder 41 is connected to the fracturing packer 40.

[0071] Continue to refer Figure 1 The upper end of the oil pipe 1 is connected with an oil pipe tee 44, the upper opening of the oil pipe tee 44 is connected with a plug 43, and a catcher 45 connected with the plug 43 is arranged in the oil pipe tee 44; the upper end of the casing 47 is connected with the casing tee 48 through a flange 2, and the oil pipe 1 is hung on the casing tee 48 through a pipe hanger 46. When in use, the designed integrated fracturing and drainage test string is lowered to a predetermined position downhole, and then the fracturing packer 40 is set to isolate the oil casing annulus from the target layer, and then the string is hung at the wellhead through the pipe hanger 46, and the upper part of the pipe hanger 46 is connected to the oil pipe tee 44 or the Christmas tree, and then the pressure gauge connected to the pump core is put into the pipe from the upper opening of the oil pipe tee 44, and then the upper end of the oil pipe tee 44 is blocked with the catcher 45 connected to the plug 43, and finally the ground injection system is connected, so that the power fluid is pumped into the pipe from the flank of the oil pipe tee 44, and the pump core is pumped into the pump seat. It should be added that the sand support 38 can prevent the formation sand from being deposited on the top of the packer and causing the sand to bury the packer. The full-bore pressure gauge support 41 can be installed with 2 to 4 electronic pressure gauges to monitor the entire construction process.

[0072] Regarding the pump seat, specifically:

[0073] refer to Figure 3The circulation control assembly includes an upper fork 9, a float valve 10 and a lower fork 11, and the upper fork 9, the float valve 10 and the lower fork 11 are sequentially distributed from the threaded connection between the outer sleeve 3 and the center tube 4 to the direction away from the threaded connection, and the upper fork 9 and the lower fork 11 are spline-matched with the outer sleeve 3 and cannot rotate; the upper fork 9 and the float valve 10 are provided with a plurality of first short saw teeth 12 extending along their respective circumferential directions on the opposite end surfaces; the float valve 10 can slide along the axial direction of the flow passage 5 to block Or conduct the flow passage 5 between the second circulation hole 7 and the first circulation hole 6, the end surface of the float valve 10 opposite to the lower fork 11 is provided with two symmetrically distributed long saw teeth 13; the end surface of the lower fork 11 opposite to the float valve 10 is provided with two second short saw teeth 14 and a plurality of third short saw teeth 15 extending along its circumference and used to mesh with the long saw teeth 13, wherein the two second short saw teeth 14 are symmetrically distributed about the axis of the lower fork 11, and the plurality of third short saw teeth 15 are flush with each other and higher than the second short saw teeth 14. The first sealing ring 16 and the second sealing ring 17 are respectively embedded inside and outside the float valve 10; the first sealing ring 16 abuts between the float valve 10 and the center tube 4; the second sealing ring 17 abuts between the float valve 10 and the outer sleeve 3.

[0074] Specifically, Figure 3 As shown, the upper end surface of the float valve 10 is provided with 12 first short saw teeth 12, and the lower end surface of the float valve 10 is provided with two symmetrical long saw teeth 13; the lower end surface of the upper fork 9 is provided with 12 first short saw teeth 12; the upper end surface of the lower fork 11 is also provided with 12 saw teeth, but two symmetrical saw teeth (i.e., the second short saw teeth 14) are deeper than the other saw teeth (i.e., the third short saw teeth 15). It should be noted that the number of the relevant saw teeth is not limited to the above.

[0075] Combination Figure 2 and Figure 3 As shown, when the pressure outside the outer sleeve 3 is greater than the pressure inside the sleeve, the float valve 10 will move downward, and after contacting the relevant saw teeth on the lower fork 11, since the two long saw teeth 13 at the lower end of the float valve 10 differ from the saw teeth on the lower fork 11 by half a saw tooth angle, the float valve 10 must rotate half a saw tooth angle to continue to move downward, and after the rotation, the saw teeth at the upper end of the float valve 10 differ from the saw teeth at the lower end of the upper fork 9 by half a saw tooth angle; when the pressure inside the outer sleeve 3 is greater than the pressure outside the sleeve, the float valve 10 will move upward, and after contacting the saw teeth under the upper fork 9, the float valve 10 will rotate half a saw tooth angle again; in this way, the float valve 10 will move up and down under the action of the positive and negative pressure difference inside and outside the sleeve, and will also perform rotational motion. When the float valve 10 rotates to the position shown in FIG. Figure 4When the float valve 10 is in the position shown, the downward distance of the float valve 10 will be greater, so that the first sealing ring 16 on the float valve 10 will move down to the bottom of the second circulation hole 7. At this time, the second circulation hole 7 will be connected to the first circulation hole 6, and the circulation channel on the pump seat will be opened; when it is desired to close after opening, the oil casing annulus can be opened for large displacement positive circulation, and the second circulation hole 7 on the center pipe 4 will generate flow resistance, thereby forming a pressure difference between the inside and outside of the pipe to push up the float valve 10, and the circulation channel on the pump seat can be closed.

[0076] In the above design, when the pump seat is put into the well, its circulation channel can be set to an open state or a closed state. When it is set to an open state, after the downhole tubing is set, the pump core can be put into the pump to conduct a drainage test; when it is set to a closed state, the casing annulus (outside the oil pipe 1) can be pressurized to about 5MPa and maintained, and then the oil pipe 1 can be pressurized to about 10MPa and then released, and then pressurized to 10MPa and released again. When it is pressed to 10MPa for the third time and then released, the pressure in the casing annulus will also be released at the same time, indicating that the circulation channel on the pump seat has been opened.

[0077] Regarding the pump element, specifically:

[0078] refer to Figure 4 The pump core includes a nozzle 18, a diffuser 19, an outer cylinder 20 and a flow nipple 21; the diffuser 19 is provided with a main flow channel 22 and a secondary flow channel 23 which are spaced apart, and both the main flow channel 22 and the secondary flow channel 23 are connected to the nozzle 18; the outer cylinder 20 is sleeved on the diffuser 19, and a flow annular cavity 24 which is connected to the secondary flow channel 23 is formed between the outer cylinder 20 and the diffuser 19; the flow nipple 21 is threadedly connected to the outer cylinder 20 and also to the diffuser 19, and the flow nipple 21 is provided with a main channel 25, one end of the main channel 25 is connected to the main flow channel 22, and the other end is closed; along the axial direction of the flow nipple 21, a side channel 26 which is spaced apart from the main channel 25 is provided on the side wall of the flow nipple 21, and the side channel 26 is connected to the flow annular cavity 24; the flow nipple 21 is provided with a drainage hole 8 which runs through its side wall, and the drainage hole 8 is connected to the main channel 25.

[0079] The flow nipple 21 is also provided with a blind cavity 27, and in the axial direction of the flow nipple 21, the blind cavity 27 is spaced apart from the main channel 25; the side channel 26 extends from the flow ring cavity 24 to communicate with the blind cavity 27; the pump core also includes a lower joint 28 and a shut-in valve 29; the lower joint 28 is threadedly connected to the flow nipple 21 and communicates with the blind cavity 27; the shut-in valve 29 is arranged in the blind cavity 27 and is located in the space enclosed by the lower joint 28 and the flow nipple 21, and is used to block or conduct the lower joint 28, so as to correspondingly block or establish the communication between the lower joint 28 and the side channel 26. Here, when the shut-in valve 29 abuts against the lower joint 28, the fifth sealing ring 49 embedded in the shut-in valve 29 abuts against the inner wall of the lower joint 28.

[0080] Above the second circulation hole 7, the inner wall of the central tube 4 is machined with a first smooth sealing surface and a step 32, and below the second circulation hole 7, a second smooth sealing surface is machined. After the pump core is put into operation, it will sit on the step 32, and at the same time, the two sealing surfaces will form a sealing match with the third sealing ring 30 and the fourth sealing ring 31 on the pump core respectively, and the positive circulation input power fluid can be used for jet pump discharge.

[0081] The pump core also includes a leather cup shaft 33, a leather cup 34, a leather cup seat 35, a fishing head 36 and a filter screen 37; the leather cup shaft 33 is sleeved on the nozzle 18 and is threadedly connected to the nozzle 18, and is also threadedly connected to the end of the outer tube 20 away from the flow short section 21; the leather cup 34 is sleeved on the leather cup shaft 33; the leather cup seat 35 is connected between the leather cup shaft 33 and the fishing head 36, and abuts against the leather cup 34, and a check valve 50 is arranged in the leather cup seat 35; the fishing head 36 is provided with a flow hole passing through its side wall, and the filter screen 37 is arranged on the side wall of the fishing head 36 to block the flow hole.

[0082] refer to Figures 1 to 4 When discharging liquid, the pump core is pumped downhole. After being seated, the two groups of third sealing rings 30 and fourth sealing rings 31 on the pump core will just cross-seal a group of circulation holes on the pump seat. At this time, the high-pressure power fluid will flow downward after being filtered by the filter screen 37, and enter the nozzle 18 after the one-way valve is pushed open, thereby generating a high-speed jet; a negative pressure suction area will be formed around the high-speed jet, so that the formation fluid will be sucked from the side hole on the lower joint 28. After the formation fluid enters the lower joint 28, the well valve 29 will be opened, and the side channel 26, the flow ring cavity 24, and the secondary flow channel 23 will be entered into the periphery of the diffuser 19 through the blind cavity 27, and then mixed with the high-speed jet and enter the main channel 22 for expansion and pressure reduction, and finally enter the circulation channel from the main channel 25 and the drainage hole 8, and enter the oil casing annulus from the circulation channel, and then be discharged from the ground through the casing tee 48. When the well needs to be shut down, it is only necessary to stop the pump, and then apply a balanced pressure to the inside and outside of the pipe at the same time, so that the shut-in valve 29 is always in a reverse pressurized state. The operation is simple and reliable.

[0083] When the pump is started for reverse circulation, the check valve 50 is closed to block the pressure relief passage leading to the pipe, so that the pump core can be smoothly lifted out of the pump seat. When backwashing to the wellhead, the pump core is captured by the catcher 45, the plug 43 is removed to take out the pump core and the pressure gauge, and the pressure gauge data can be played back to understand the test results as soon as possible.

[0084] In the present invention, the pump seat is designed as a hydraulic multiple-opening type pump seat, the pump core adopts a positive circulation discharge and reverse circulation pumping working mode, and a shut-in valve 29 is set at the formation fluid inlet in the pump core. The shut-in valve 29 is opened during discharge and closed after reverse pressurization, and can be reliably sealed to realize downhole well opening and closing. A pressure gauge can be connected below the pump core to obtain formation pressure data during discharge flow and shut-in recovery.

[0085] The repeated switching of the hydraulic multiple switching pump seat is to make the float valve 10 move up and down by creating the positive and negative pressure difference inside and outside the cylinder, and rotate an angle under the action of the upper fork 9 and the lower fork 11, and the lower fork 11 is provided with an open position and a closed position. When the float valve 10 rotates to the open position, the float valve 10 can move down a large distance, so that the first circulation hole 6 is connected with the second circulation hole 7. At this time, the circulation channel is opened, and the pump core can be put in for drainage test. After the test, the pump core is pulled out by reverse circulation. When it is necessary to close the circulation channel on the pump seat, the float valve 10 can be moved up from the large displacement positive circulation in the pipe, and the circulation channel is closed. After the pump seat is closed, fracturing construction can be carried out. After the fracturing construction is completed, the circulation channel on the pump seat is opened again by the positive and negative pressure difference inside and outside the cylinder, and the pump core is put in for drainage test after fracturing. In this way, the formation can be tested and compared before and after fracturing, so as to make an objective evaluation of the fracturing effect.

[0086] The present invention also provides a method for constructing an integrated pipe string for fracturing and drainage testing. The method is based on the above-mentioned integrated pipe string for fracturing and drainage testing, and comprises the following steps:

[0087] S100: Pre-fracture test:

[0088] S110: Lower the integrated fracturing and drainage test string to the predetermined position underground, then seal the fracturing packer 40, and install the tubing hanger 46, tubing tee 44 or Christmas tree at the wellhead, and connect the ground injection system at the same time; S120: Open the circulation channel on the pump seat by hydraulic means, then put the pump core connected to the pressure gauge into the tubing 1, and pump it to the pump seat, and then pump pressure to the pump core; S130: After multiple drainages, reverse circulation is performed to remove the pump core and the pressure gauge; S200: After removing the pump core, close the circulation channel on the pump seat by a large-displacement positive circulation method, and then perform fracturing operations; S300: After the fracturing operation is completed, the circulation channel on the pump seat is opened by hydraulic means, and the pump core is put in again. After multiple drainages, the pump core and the pressure gauge are removed again.

[0089] Specifically, the integrated string for fracturing and drainage testing is designed from top to bottom as follows: tubing 1 + hydraulic multiple-switch pump seat + sand holder 38 + interval tubing 39 + fracturing packer 40 + full-bore pressure gauge holder 41. During operation, the designed operation string is lowered to the predetermined position underground, and then the fracturing packer 40 is sealed, and the tubing hanger 46, tubing tee 44 or Christmas tree are installed at the wellhead, the ground injection system is connected, and the circulation channel on the pump seat is opened hydraulically; after the circulation channel is opened, the pressure gauge connected to the pump core is put into the operation tubing 1 and pumped to the pump seat, forming a sealed match with the pump seat, and continuing to increase the pressure, and the nozzle 18 generates a high-speed jet, which is sucked into the annulus of the oil casing by cooperation with the diffuser 19, and returned to the ground together with the power fluid, which is the initial flow. After assisting drainage for a period of time, the pump is stopped. At this time, the formation pressure has been reduced, and the shut-in valve 29 in the pump core will be in a reverse pressurization state, thereby realizing downhole well shut-in, which is the initial well shut-in; in order to prevent the formation pressure from exceeding the static liquid column pressure on the valve in the later stage of recovery, the shut-in valve 29 is opened. After stopping the pump, a balance pressure can be applied to the inside and outside of the pipe as soon as possible and maintained to ensure that the shut-in valve 29 is always in a reverse pressurization state; after the initial shut-in for a period of time, the oil casing annulus is opened first, and then the surface pump is started to discharge the liquid, which is the secondary flow; after the secondary flow is completed, the pump is stopped again, the balance pressure is applied, and the secondary well is shut-in, so that multiple downhole wells can be opened and closed. The downhole pressure gauge will record the pressure and temperature changes at every moment during the construction process, which is the pre-fracturing test. After the test is completed, the pump core and the pressure gauge are pulled out by reverse circulation, and the pressure gauge data can be played back to explain the pre-fracturing test.

[0090] Following the above, after the pre-fracturing test is completed, the circulation channel on the pump seat is closed by a large displacement positive circulation method. After the pump seat is closed, the formation can be fracturing. After the fracturing operation is completed, the circulation channel on the pump seat is opened by hydraulic means, and the pump core is put into the pump for the post-fracturing drainage test. After the test is completed, the pump core and the pressure gauge are pulled out by reverse circulation. The pressure gauge data can be played back to explain the post-fracturing test. By comparing and analyzing the test results before and after fracturing, an objective evaluation of the fracturing construction effect can be made.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fracturing fluid discharge test integrated pipe string, characterized in that: include: Oil pipe (1), pump seat, pump core and pressure gauge; The pump seat is arranged at one end of the oil pipe (1), and comprises an outer sleeve (3), a central pipe (4) and a circulation control component; The outer sleeve (3) is sleeved on the central tube (4) and is threadedly connected to the central tube (4), and a flow passage (5) is formed between the outer sleeve (3) and the central tube (4); The outer sleeve (3) is provided with a first circulation hole (6) penetrating through its side wall, and the first circulation hole (6) is communicated with the flow passage (5); The central tube (4) is provided with a second circulation hole (7) penetrating through its side wall, and the second circulation hole (7) is also connected to the flow passage (5); The circulation control component is arranged in the flow passage (5) and is used to control the on-off of the flow passage (5) between the second circulation hole (7) and the first circulation hole (6); The pump core is used to be mounted on the inner wall of the central tube (4) and has a drainage hole (8). The drainage hole (8) can be connected to the second circulation hole (7) in the mounted working state. The pressure gauge is connected to the pump core.

2. The integrated pipe string for fracturing fluid discharge testing according to claim 1, characterized in that: The circulation control assembly comprises an upper shift fork (9), a float valve (10) and a lower shift fork (11), and the upper shift fork (9), the float valve (10) and the lower shift fork (11) are sequentially arranged from a threaded connection between the outer sleeve (3) and the center tube (4) to a direction away from the threaded connection; The upper shift fork (9) is arranged on the inner wall of the outer sleeve (3), and the end surface opposite to the float valve (10) is provided with a plurality of first short saw teeth (12) extending along the respective circumferential directions; The float valve (10) can slide along the axial direction of the flow passage (5) to block or conduct the flow passage (5) between the second circulation hole (7) and the first circulation hole (6), and two symmetrically distributed long saw teeth (13) are provided on the end surface of the float valve (10) opposite to the lower fork (11); The lower shift fork (11) is arranged on the inner wall of the outer sleeve (3), and is provided with two second short saw teeth (14) and a plurality of third short saw teeth (15) extending along its circumference and used to mesh with the long saw teeth (13) on the end surface opposite to the float valve (10), wherein the two second short saw teeth (14) are symmetrically distributed about the axis of the lower shift fork (11), and the plurality of third short saw teeth (15) are flush with each other and higher than the second short saw teeth (14).

3. The integrated pipe string for fracturing fluid discharge testing according to claim 2, characterized in that: A first sealing ring (16) and a second sealing ring (17) are respectively embedded inside and outside the float valve (10); The first sealing ring (16) is in contact between the float valve (10) and the central tube (4); The second sealing ring (17) abuts between the float valve (10) and the outer sleeve (3).

4. The integrated pipe string for fracturing fluid discharge testing according to claim 1, characterized in that: The pump core comprises a nozzle (18), a diffuser (19), an outer cylinder (20) and a flow nipple (21); The diffuser (19) is provided with a main flow channel (22) and a secondary flow channel (23) which are spaced apart from each other, and the main flow channel (22) and the secondary flow channel (23) are both connected to the nozzle (18); The outer cylinder (20) is sleeved on the diffuser (19), and forms a flow annular cavity (24) between the outer cylinder and the diffuser (19) and the flow annular cavity (24) is communicated with the secondary flow channel (23); The flow nipple (21) is threadedly connected to the outer cylinder (20) and is also threadedly connected to the diffuser (19). The flow nipple (21) is provided with a main channel (25). One end of the main channel (25) is connected to the main channel (22) and the other end is closed. Along the axial direction of the flow short section (21), a side channel (26) is provided on the side wall of the flow short section (21) and is spaced apart from the main channel (25), and the side channel (26) is communicated with the flow annular cavity (24); The flow nipple (21) is provided with the drainage hole (8) penetrating the side wall thereof, and the drainage hole (8) is communicated with the main channel (25).

5. The integrated pipe string for fracturing fluid discharge testing according to claim 4, characterized in that: The flow nipple (21) is further provided with a blind cavity (27), and in the axial direction of the flow nipple (21), the blind cavity (27) is spaced apart from the main channel (25); The side channel (26) extends from the flow ring cavity (24) to communicate with the blind cavity (27); The pump core also includes a lower joint (28) and a shut-off valve (29); The lower joint (28) is threadedly connected to the flow nipple (21) and communicates with the blind cavity (27); The shut-in valve (29) is arranged in the blind cavity (27) and is located in the space enclosed by the lower joint (28) and the flow nipple (21), and is used to block or open the lower joint (28) to correspondingly block or establish the communication between the lower joint (28) and the side channel (26).

6. The integrated pipe string for fracturing fluid discharge testing according to claim 5, characterized in that: A third sealing ring (30) and a fourth sealing ring (31) are respectively embedded outside the flow nipple (21) and outside the lower joint (28); In the axial direction of the flow nipple (21), the third sealing ring (30) and the fourth sealing ring (31) are distributed on both sides of the drainage hole (8), and can abut against the inner wall of the central tube (4) in a sitting condition.

7. The integrated pipe string for fracturing fluid discharge testing according to claim 4, characterized in that: The inner wall of the central tube (4) is provided with a step (32), and the flow nipple (21) abuts against the step surface.

8. The integrated pipe string for fracturing fluid discharge testing according to claim 4, characterized in that: The pump core also includes a leather cup shaft (33), a leather cup (34), a leather cup seat (35), a fishing head (36) and a filter screen (37); The leather cup shaft (33) is sleeved on the nozzle (18) and is threadedly connected to the nozzle (18), and is also threadedly connected to the end of the outer tube (20) away from the flow nipple (21); The leather cup (34) is sleeved on the leather cup shaft (33); The leather cup seat (35) is connected between the leather cup shaft (33) and the fishing head (36), and is in contact with the leather cup (34), and a check valve is arranged in the leather cup seat (35); The fishing head (36) is provided with a flow hole penetrating through its side wall, and the filter screen (37) is arranged on the side wall of the fishing head (36) and blocks the flow hole.

9. The integrated pipe string for fracturing fluid discharge testing according to any one of claims 1 to 8, characterized in that: The integrated fracturing and drainage testing string also includes a sand support (38), a spacer oil pipe (39), a fracturing packer (40) and a full-bore pressure gauge support tube (41) which are sequentially distributed along the axial direction of the oil pipe (1); The sand supporter (38) is connected to the pump seat, the spacer oil pipe (39) is connected between the sand supporter (38) and the fracturing packer (40), and the full-bore pressure gauge support tube (41) is connected to the fracturing packer (40).

10. A method for constructing an integrated pipe string for fracturing and drainage testing, characterized in that: The integrated pipe string for fracturing and drainage testing according to any one of claims 1 to 9 comprises the following steps: S100: Pre-fracture test: S110: lowering the integrated fracturing and drainage test string to a predetermined position underground, then sealing the fracturing packer (40), installing the tubing (1) hanger, tubing (1) tee or Christmas tree at the wellhead, and connecting the surface injection system; S120: opening the circulation channel on the pump seat by hydraulic means, then putting the pump core connected to the pressure gauge (2) into the oil pipe (1), pumping it to the pump seat, and then pumping pressure to the pump core; S130: After multiple discharges, reverse circulation is performed to remove the pump core and the pressure gauge (2); S200: After the pump core is removed, the circulation channel on the pump seat is closed through a large displacement positive circulation method, and then the fracturing operation is carried out; S300: After the fracturing operation is completed, the circulation channel on the pump seat is opened by hydraulic means, and the pump core is put into operation again. After multiple drainages, the pump core and the pressure gauge (2) are removed again.

Images