Coiled tubing drag fracturing method and pumping system

Abstract

The application relates to a coiled tubing drag fracturing method and a pumping system, wherein the main technical scheme is a coiled tubing drag fracturing method which comprises the following steps: S1, equipment installation; S2, depth calibration and seal checking; S3, sandblasting and perforation; S4, circulation displacement; S5, trial squeezing; S6, main fracturing; S7, unsealing; S8, pipe column lifting; and S9, well closing; wherein in the trial squeezing step, trial squeezing liquid is pumped into the coiled tubing, the trial squeezing liquid is rapidly sprayed out through a nozzle to form a high-speed jet flow, carrying liquid is pumped into an annular space, and the carrying liquid is used for carrying the debris in the annular space to move or pushing the debris in the annular space to move towards the hole eye direction. The application can reduce the plugging of the hole eye.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of tubing fracturing technology, in particular to a coiled tubing drag fracturing method and a pumping system. BACKGROUND

[0002] Coiled tubing fracturing has been applied in oil and gas field development since the 1980s. It is a very efficient unlimited segmented fracturing technology. In particular, coiled tubing bottom seal drag fracturing has obvious advantages: it can realize large displacement pumping, one trip string can realize multiple repeated setting and perforation, interlayer conversion is fast, and it also has a circulation channel in the case of abnormal operation. Therefore, coiled tubing bottom seal drag fracturing is widely used in horizontal well fracturing of tight gas, conventional oil and gas, and coalbed methane.

[0003] The existing coiled tubing drag fracturing method includes sandblasting perforation, circulation displacement and fracturing. The sandblasting perforation is to inject perforating sand and slickwater containing sand liquid into the coiled tubing, the sand liquid is radially sprayed out through the nozzle on the coiled tubing to shoot the casing, the casing forms a hole, and the sand liquid acts on the formation through the hole to form a "spindle cavity". At this time, there are debris in the annulus, including residual perforating sand, casing steel debris, and rock chunks formed by the hole formation of the formation, especially in the debris layer and coal seam, a large number of chunks are easily formed. The circulation displacement is to inject slickwater without perforating sand into the coiled tubing to displace the perforating sand in the coiled tubing into the annulus and to displace the small-particle-size debris in the annulus to the wellhead as much as possible. The fracturing is to sequentially inject preflush, sand-carrying fluid and displacement fluid into the annulus to form a fracture in the formation through the spindle cavity and to fill it.

[0004] Although the circulation displacement can displace the debris in the annulus, due to the limited displacement of the coiled tubing, only small debris can be displaced to the wellhead, and large debris is difficult to be circulated out of the wellhead. Therefore, during the fracturing injection stage, as the annular fracturing displacement increases, the debris not circulated out of the annulus will be brought back to the deep part of the casing by the fracturing fluid in the annulus and enter the formation through the hole. During this process, debris of various particle sizes will move to the hole and deposit at the hole position. When large-particle-size debris is blocked in the hole and small-particle-size debris forms an embedding effect, the fluid channel will be blocked, and eventually a bridge plug will be formed at the casing hole position. In the case where the hardness of the blocked debris is high, the casing pressure limit cannot be broken to break the blocked bridge plug, resulting in failure to normally fracture. SUMMARY

[0005] In order to reduce the plugging of the hole, the present application provides a coiled tubing drag fracturing method and a pumping system.

[0006] The coiled tubing drag fracturing method provided by the present application adopts the following technical scheme:

[0007] A coiled tubing drag fracturing method comprises the following steps:

[0008] S1, equipment installation;

[0009] S2, depth calibration and seal verification: after the dragging tool is lowered to the perforated layer, the depth is calibrated, and the seat seal is performed after passing the verification; the packer avoids the position of the casing coupling, and the pressure seal is tested;

[0010] S3, sandblasting perforation: the sand-containing liquid is pumped into the coiled tubing, the sand-containing liquid is sprayed to the casing through the nozzle of the coiled tubing to perforate the casing, the casing forms a hole, and the sand-containing liquid forms a cavity in the formation through the hole;

[0011] S4, circulation displacement: the circulating fluid is pumped into the coiled tubing to displace the sand-containing liquid in the coiled tubing through the nozzle into the annulus;

[0012] S5, test squeeze: the test squeeze liquid is pumped into the coiled tubing, the test squeeze liquid is quickly sprayed through the nozzle to form a high-speed jet, the carrying liquid is pumped into the annulus, and the carrying liquid is used to carry the debris in the annulus or move the debris in the annulus towards the hole direction;

[0013] S6, main fracturing;

[0014] S7, unsealing;

[0015] S8, pipe column lifting: the coiled tubing is lifted, and the steps S2-S7 are repeated to complete the whole well fracturing construction;

[0016] S9, well closure.

[0017] By adopting the above technical scheme, in step S4, the circulating fluid displaces the sand-containing liquid in the coiled tubing through the nozzle into the annulus, and tries to take out the perforating sand and small-particle debris in the annulus from the wellhead, while the medium and large-particle debris is difficult to be taken out, these debris are often scattered in the annulus, and the larger debris is more difficult to be carried by the circulating fluid, and the debris is more concentrated near the hole; in step S5, the nozzle of the coiled tubing continuously sprays the test squeeze liquid towards the hole to form a high-speed jet, according to the wellbore condition, the carrying liquid is pumped into the annulus, the carrying liquid carries the debris in the annulus towards the deep part of the casing, that is, towards the hole position, in this process, due to the different sizes and qualities of the debris and the different scattering positions of various debris in the circulation displacement stage, the smaller debris is carried faster, while the large debris is difficult to be directly carried, the carrying liquid pushes the debris in the form of rolling towards the hole, and the speed is slow, in this way, by using the different moving speeds and positions of different debris, the time for different debris to reach the hole is different, that is, there is a time difference, so that different debris will be orderly moved to the high-speed jet to reduce the situation that a large amount of debris accumulates near the hole in a short time and causes the hole to be blocked.

[0018] When the cuttings are orderly moved to the high-speed jet, a negative pressure is formed at the high-speed jet according to Bernoulli's principle, so that the cuttings orderly moved to the high-speed jet are adsorbed and rapidly injected into the hole and then brought to the formation, thereby reducing the residence time of the cuttings in the hole and further reducing the plugging.

[0019] Optionally, in step S5, the displacement of the carrying fluid is stepped up, and each step displacement maintains an injection time t, t=Aa / R, wherein Aa is the annulus volume, and R is the step displacement.

[0020] By adopting the technical scheme, first, by setting the stepped annulus displacement, the driving effect and driving speed of different cuttings are different under different step displacements, so that different cuttings can be orderly discharged from the hole in sequence and then ejected by the high-speed jet, thereby reducing the plugging of the hole caused by the accumulation of a large amount of cuttings near the hole in a short time. And, under each step displacement, a capacity of a horizontal section can be injected, that is, each type of cuttings can be driven as completely as possible, especially for the cuttings accumulated at the horizontal section or the large inclination section, to ensure that the cuttings in the annulus are cleaned.

[0021] Secondly, the stepped annulus displacement can reduce the instantaneous high pressure of the casing to ensure the safety of the equipment.

[0022] Optionally, when the straight well is constructed, in step S5, the test fluid keeps the high-speed jet state, the annulus stops injecting and discharging fluid, and the stop duration is greater than 5 min, and then the carrying fluid is pumped into the annulus.

[0023] By adopting the technical scheme, for the case of the straight well, in step S5, the annulus stops injecting and discharging fluid, and since the annulus is full of circulating fluid during the circulating displacement stage, the circulating fluid carries the cuttings not discharged by the circulation, at this time, the circulating fluid in the annulus is stationary, and the cuttings sink, and since the densities of the cuttings are different, the sinking speeds of the cuttings are different, and the smaller the density of the cuttings, the slower the sinking speed of the cuttings, that is, different sizes of the cuttings will sink to the hole in sequence, and under the high-speed jet condition, according to Bernoulli's principle, the orderly sinking cuttings are rapidly injected into the hole and then brought to the formation, thereby reducing the residence time of the cuttings in the hole and further reducing the plugging.

[0024] After sinking for a period of time, the carrying fluid is pumped into the annulus, further accelerating the sinking speed of the cuttings, especially the driving sinking of the small cuttings, to bring the cuttings with slow sinking speed to the high-speed jet position and then eject them, which not only accelerates the cleaning speed, but also ensures that the hole is not easily plugged.

[0025] Optionally, in step S5, the displacement of the test fluid in the coiled tubing is greater than or equal to 0.5 m³ / min.

[0026] By adopting the technical scheme, the high-displacement test extrusion liquid is arranged to ensure the high-speed jet flow of the nozzle, to ensure the carrying and shooting effect on the debris, and to protect the equipment.

[0027] Optionally, in step S5, the final displacement of the carrying liquid in the annulus is 3-5 m³ / min.

[0028] By adopting the technical scheme, the high-displacement test extrusion liquid is arranged to ensure the high-speed jet flow of the nozzle, to ensure the carrying and shooting effect on the debris, and to protect the equipment.

[0029] Optionally, in step S5, the nozzle jet speed of the coiled tubing is 110-130 m / s.

[0030] Optionally, in step S5, the test extrusion liquid is slick water, and the carrying liquid is active water.

[0031] By adopting the technical scheme, the use of slick water in the coiled tubing reduces the friction, thereby reducing the pressure of the coiled tubing, and the use of active water in the annulus can reduce the cost to a certain extent.

[0032] Optionally, in step S6, the coiled tubing continuously supplements the liquid, and the displacement is 0.1-0.2 m³ / min.

[0033] By adopting the technical scheme, the supplement of the liquid reduces the sand entering the coiled tubing in the fracturing stage, and maintains a certain pressure in the lumen of the coiled tubing, thereby reducing the influence of the extrusion of the annulus on the coiled tubing.

[0034] The pumping system provided in the application adopts the following technical scheme:

[0035] The pumping system comprises a sand tank group, a slick water tank group, an active water tank group, a liquid supplement tank group, a sand mixing truck, a low-pressure manifold, a first fracturing truck group, a high-pressure manifold, a second fracturing truck group, a coiled tubing truck, and a blowout tank.

[0036] By adopting the technical scheme, the specific arrangement of the pumping system is set, the use of the first fracturing truck is reasonably utilized, the equipment is maximized, and the use rate of other equipment is reduced, and the displacement control and process inversion are more rapid and convenient.

[0037] Optionally, a supplementary water tank is further included, the supplementary water tank is connected with the inlet of one of the first fracturing trucks, and the height of the supplementary water tank is higher than that of the first fracturing truck; in step S4, the circulating fluid is pumped into the coiled tubing by the coiled tubing truck, and the displacement of the circulating fluid is 0.6-0.8 m3 / min; in step S5, only the supplementary water tank supplies the first fracturing truck with the test squeeze fluid, and the displacement of the test squeeze fluid is greater than or equal to 0.5 m3 / min.

[0038] By adopting the technical scheme, the supplementary water tank is set, the hydraulic pressure difference is utilized, sufficient liquid supply pressure is ensured, the test squeeze fluid is supplied to the coiled tubing, and the pump injection system is simplified, thereby saving cost.

[0039] Furthermore, the use of the single first fracturing truck is set, the use rate of other equipment is reduced, the displacement is more easily controlled, and the process is rapid, convenient and accurate.

[0040] In summary, the present application has at least one of the following beneficial technical effects:

[0041] 1. By setting the test squeeze step, the nozzle of the coiled tubing continuously shoots the test squeeze fluid towards the perforation to form a high-speed jet flow, the carrying fluid is pumped into the annulus, the carrying fluid moves the debris in the annulus towards the deep part of the casing, the moving speed and position of different debris are different, the time when different debris reaches the vicinity of the perforation is different, that is, there is a time difference, different debris is sequentially moved to the high-speed jet flow to reduce the situation that a large amount of debris accumulates near the perforation in a short time and causes the perforation to be blocked; when the debris is sequentially moved to the high-speed jet flow, a negative pressure is formed at the high-speed jet flow according to Bernoulli's principle, the debris sequentially moved to the high-speed jet flow is adsorbed and quickly injected into the perforation, and then brought to the formation, thereby reducing the residence time of the debris in the perforation and further reducing the blockage.

[0042] 2. By setting the stepwise increasing annulus displacement, the driving effect and driving speed of different debris are different under different stepwise displacements, so that different debris can be sequentially discharged through the perforation by the high-speed jet flow, thereby reducing the situation that a large amount of debris accumulates near the perforation in a short time and causes the perforation to be blocked. Furthermore, one horizontal section capacity can be injected under each stepwise displacement, that is, each type of debris can be driven as completely as possible, especially for the driving of the debris accumulated at the horizontal section or the large deviation section, to ensure that the debris in the annulus is cleaned.

[0043] 3. For the case of vertical wells, before the annulus opens the displacement, the annulus stops the liquid injection and drainage, and gives a standing sedimentation time, so that the debris sinks, because the density of the debris is different, the sinking speed is different, that is, debris of different densities will sink to the hole in turn, and in the case of high-speed jet flow, the Bernoulli principle is used to quickly shoot the orderly sinking debris into the hole and carry it to the formation, reduce the blockage, and after sinking for a period of time, the carrying fluid is pumped into the annulus, further accelerating the sinking speed of the debris, so that the debris with slow moving speed is shot out at the high-speed jet flow position, and the cleaning speed is accelerated;

[0044] 4. By setting the specific arrangement of the pumping system, the use of the first fracturing truck is reasonably utilized, the equipment is maximized, and the use of other equipment is reduced, and the displacement control and process inversion are more rapid and convenient. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is a flowchart of the pumping system of the embodiment in the sandblasting perforation step.

[0046] Figure 2 is a flowchart of the coiled tubing drag fracturing method of the embodiment.

[0047] Figure 3 is a flowchart of the pumping system of the embodiment in the trial squeezing step.

[0048] Figure 4 is a flowchart of the pumping system of the embodiment in the main fracturing step. DETAILED DESCRIPTION

[0049] The following will be described in detail in combination with the accompanying Figures 1-4 The application is further described in detail.

[0050] The embodiment of the application discloses a pumping system, referring to Figure 1 The pumping system comprises an instrument vehicle, a sand tank group, a slick water tank group, an active water tank group, a liquid supplement tank group, a sand mixing vehicle, a low-pressure manifold, a first fracturing vehicle group, a high-pressure manifold, a second fracturing vehicle group, a coiled tubing vehicle and a blowout tank.

[0051] The slick water tank group can be composed of one or more slick water tanks, the liquid supplement tank group can be composed of one or more liquid supplement tanks, the active water tank group can be composed of one or more active water tanks, the first fracturing vehicle group comprises a plurality of first fracturing vehicles, and the second fracturing vehicle group comprises a plurality of second fracturing vehicles.

[0052] The active water tank group, the slick water tank group and the sand tank group are connected with the inlet of the sand mixing truck, the outlet of the sand mixing truck is connected with the inlet of the low pressure manifold, the low pressure manifold is connected with the inlets of the first fracturing trucks in the first fracturing truck group respectively, the outlets of the first fracturing trucks are connected with the high pressure manifold, and the outlet of one of the first fracturing trucks is also connected with the coiled tubing truck, the outlet of the high pressure manifold is connected with the annulus, and the outlet of the coiled tubing truck is connected with the coiled tubing.

[0053] As shown in Figure 2 , the embodiment of the application further discloses a coiled tubing drag fracturing method, which comprises the following steps:

[0054] S1, equipment installation: including installing wellhead bottom flange and cross, well passing rule, scraping pipe, exploring artificial well bottom, scraping pipe, installing fracturing wellhead, connecting ground pump injection system, pressure test.

[0055] S2, depth calibration and seal test: calibrate the depth after the drag tool is lowered to the perforation layer, and then install the packer to be seated and sealed according to the technical requirements, the packer avoids the position of the casing coupling, and the pressure test is performed.

[0056] S3, sand jetting and perforating: referring to Figure 1 (the arrow in the figure is the medium direction, the hollow arrow is the low pressure state, and the solid arrow is the high pressure state), the quartz sand in the sand tank group and the slick water in the slick water tank group are transported to the sand mixing truck, and the sand-containing liquid is prepared, the sand-containing liquid enters one of the first fracturing trucks through the low pressure manifold, the first fracturing truck is pressurized and transported into the coiled tubing truck, the coiled tubing truck pumps the sand-containing liquid into the coiled tubing at high pressure, the displacement of the sand-containing liquid in the coiled tubing is 0.6-0.8 m³ / min, the sand-containing liquid is sprayed onto the casing through the nozzle of the coiled tubing to jet off the casing, the casing forms a hole, and the sand-containing liquid passes through the hole to excavate the formation.

[0057] S4, circulating displacement: after the perforating is completed, the sand tank group stops adding sand, only the slick water tank group supplies liquid, the coiled tubing truck continues to pump the slick water into the coiled tubing, the slick water is the circulating liquid, at this time, the displacement of the circulating liquid can be consistent with the displacement of the sand-containing liquid in the S3 step, the circulating liquid replaces the sand-containing liquid in the coiled tubing into the annulus through the nozzle, and the perforating sand and small particle size debris in the annulus are taken out of the wellhead as much as possible into the blowout tank; during the process, medium and large particle size debris is difficult to be taken out, and these debris is often scattered in the annulus.

[0058] S5, test extrusion: test extrusion liquid is pumped into the coiled tubing, which can be supplied to one of the first fracturing trucks through the slick water tank group, and then the first fracturing truck transports the slick water to the coiled tubing truck, and the coiled tubing truck supplies liquid to the coiled tubing, in the embodiment, as shown inFigure 3 As shown, by adding a supplementary water tank, the supplementary water tank has slick water, the supplementary water tank is higher than the first fracturing truck, and the liquid level difference is used to supply liquid to one of the first fracturing trucks, and then the first fracturing truck delivers the slick water into the coiled tubing truck, and the coiled tubing truck supplies liquid to the coiled tubing.

[0059] The slick water in the coiled tubing is a test extrusion liquid, and the displacement thereof is greater than or equal to 0.5 m³ / min, the test extrusion liquid is rapidly sprayed through a nozzle to form a high-speed jet, the high-speed jet is aimed at the hole of the casing, and the flow rate of the high-speed jet is determined according to the size of the nozzle, and in the embodiment, the flow rate of the nozzle is 110-130 m / s.

[0060] The pumping timing and displacement of the carrying liquid in the annulus are different according to the different conditions of the wellbore, when the wellbore is a horizontal well, as shown in Figure 3 As shown, the active water tank group delivers the active water to the first fracturing truck group through the sand mixing truck, the first fracturing truck group high-pressure sends the active water into the high-pressure manifold, and the high-pressure manifold sends the active water into the annulus, the active water in the annulus is the carrying liquid, and the displacement of the carrying liquid in the annulus is 3-5 m³ / min, the carrying liquid carries the debris scattered in the annulus to move or pushes the debris in the annulus to move towards the deep part of the casing, that is, towards the hole position, in this process, due to the different sizes and masses of the debris and the different scattering positions of various debris in the circulation displacement stage, the smaller the debris is, the faster it is carried, and the large debris is difficult to be directly carried, and the carrying liquid pushes the debris in the form of rolling to move towards the hole, and the speed is slow, in this way, by using the different moving speeds and positions of different debris, the time for different debris to reach the vicinity of the hole is different, that is, there is a time difference, so that different debris will be orderly moved to the high-speed jet to reduce the situation that a large amount of debris accumulates near the hole in a short time to cause the hole to be blocked.

[0061] When the debris is orderly moved to the high-speed jet, a negative pressure is formed at the high-speed jet by using Bernoulli's principle, so as to adsorb the debris orderly moved to the high-speed jet and rapidly inject it into the hole and take it to the formation, thereby reducing the residence time of the debris in the hole and further reducing the blockage.

[0062] In other embodiments, the carrying liquid discharge can be quickly increased to 3-5 m3 / min, preferably 3-4 m3 / min at the beginning of the pump injection, although the cleanout efficiency is higher, but the debris removal speed will also be accelerated, there is a small risk of plugging, and the more optimized solution can be that in the present embodiment, the carrying liquid discharge is increased in steps, and each step discharge maintains an injection time of t, t = Aa / R, where Aa is the annulus volume and R is the step discharge, the difference between each stage discharge can be 0.5 m3 / min or 1 m3 / min, for example, if the annulus volume is 5 m3, then the 0.5 m3 / min discharge stage needs to be maintained for 10 min, the 1 m3 / min stage discharge is maintained for 5 min, the 2 m3 / min stage discharge is 2.5 min, and the last 4 m3 / min discharge needs to be maintained for 1.25 min.

[0063] In this way, the driving effect and driving speed of different debris are different under different step discharges, so that different debris can pass through the orifice in an orderly manner and be ejected by the high-speed jet, thereby reducing the accumulation of a large amount of debris near the orifice in a short period of time, which can cause the orifice to be blocked.

[0064] And, each step discharge can inject a capacity of a horizontal section, that is, each type of debris can be driven as completely as possible, especially for driving the debris accumulated at the horizontal section or the large inclination section, to ensure that the debris in the annulus is cleaned up.

[0065] When the straight well is constructed, the test liquid still maintains the high-speed jet state, and the difference from the horizontal well construction is that the annulus stops injecting and draining liquid, and the stop draining liquid is specifically closing the throttling manifold of the annulus, and the original high-pressure manifold is in a closed state during steps S4 to S5, that is, no new liquid enters the annulus, and the stop duration is greater than 5 min, preferably 5-10 min. During this process, due to the previous circulating displacement stage, the annulus is filled with circulating liquid, and the circulating liquid carries the debris that has not been displaced by the circulation. When the injection and drainage of the liquid in the annulus are stopped, the circulating liquid in the annulus is stationary, allowing the debris to sink. Since the densities of the debris are different, the sinking speeds of the debris are different, and the smaller the density of the debris, the slower the sinking speed of the debris, that is, different sizes of debris will sink to the orifice in turn, and under the condition of high-speed jet, the orderly sinking debris is quickly injected into the orifice and brought to the formation by using Bernoulli's principle, reducing the residence time of the debris in the orifice to reduce the plugging.

[0066] After sinking for a period of time, the throttling manifold and the high-pressure manifold of the annulus are opened, and the carrying liquid is pumped into the annulus. The discharge of the carrying liquid can directly reach 3-5 m3 / min, and the discharge of the carrying liquid can also be increased in steps from 0 to 3-5 m3 / min.

[0067] In the process of pumping the carrying liquid into the annulus, the descending speed of the debris is further accelerated, especially the driving of small debris to descend, so as to take this part of slow-moving debris to the high-speed jet position and shoot out, which not only accelerates the cleaning speed, but also ensures that it is not easy to be blocked.

[0068] S6, main fracturing: including preflush stage, sand-carrying fluid stage and displacement fluid stage, wherein the preflush, sand-carrying fluid and displacement fluid are pumped by the first fracturing truck group, and then enter the annulus through the high-pressure manifold.

[0069] It should be noted that during the overall process of main fracturing, the coiled tubing needs to be continuously supplemented with liquid, which can be slick water or active water, and the discharge capacity is 0.1-0.2m³ / min. The liquid is shot out from the nozzle, which will reduce the sand entering the coiled tubing during the fracturing stage, and the liquid will maintain a certain pressure in the lumen of the coiled tubing to reduce the influence of the coiled tubing under the extrusion of the annulus.

[0070] The specific pipeline cooperation of the pumping system is as shown in Figure 4 The liquid supplement tank group delivers the liquid to the second fracturing truck, the second fracturing truck delivers the liquid to the coiled tubing truck at high pressure, and the coiled tubing truck delivers the liquid to the coiled tubing.

[0071] S7, unblocking: after the displacement fluid of the main fracturing is finished, the unblocking packer is lifted.

[0072] S8, lifting the string: lifting the coiled tubing, repeating the steps S2-S7, and completing the whole well fracturing operation.

[0073] S9, shut-in: after the whole well fracturing is completed, the pump is stopped, the coiled tubing is lifted to the wellhead, the well is shut-in, and the wellhead equipment is removed.

[0074] The above are the preferred embodiments of the present application, and are not limited to the protection scope of the present application, therefore: any equivalent changes made according to the structure, shape, principle of the present application should be covered within the protection scope of the present application.

Claims

1. A coiled tubing drag fracturing method characterized by: The method comprises the following steps: S1, equipment installation; S2, depth calibration and seal verification: after the floor cleaning tool is lowered to the perforated layer, the depth is calibrated, and the seat seal is performed after passing the qualification. The packer avoids the casing coupling position, and the pressure seal is tested; S3, sand jet perforation: the sand-containing liquid is pumped into the coiled tubing, and the sand-containing liquid is sprayed to the casing through the nozzle of the coiled tubing to perforate the casing, so that the casing forms a hole, and the sand-containing liquid forms a cavity in the formation through the hole; S4, circulation displacement: the circulating fluid is pumped into the coiled tubing to displace the sand-containing liquid in the coiled tubing through the nozzle into the annulus; S5, test squeeze: the test squeeze fluid is pumped into the coiled tubing, the test squeeze fluid is sprayed out through the nozzle at high speed to form a high-speed jet, and the carrying fluid is pumped into the annulus, and the carrying fluid is used to carry the debris in the annulus or move the debris in the annulus towards the hole direction; S6, main fracturing; S7, unsealing; S8, pipe string lifting: the coiled tubing is lifted, and the steps S2-S7 are repeated to complete the whole well fracturing operation; S9, well shut-in; In step S5, the displacement of the carrying fluid is increased in steps, and each step displacement maintains an injection time t, t=Aa / R, wherein Aa is the annulus volume, and R is the step displacement; when the straight well is constructed, in step S5, the test squeeze fluid maintains a high-speed jet state, the annulus stops injecting and discharging liquid, and the stop duration is greater than 5 min, and then the carrying fluid is pumped into the annulus.

2. The coiled tubing, drag fracturing method of claim 1, characterized in that: In step S5, the displacement of the test squeeze fluid in the coiled tubing is greater than or equal to 0.5 m³ / min.

3. The coiled tubing, bullheaded fracturing method of claim 1, characterized in that: In step S5, the final displacement of the carrying fluid in the annulus is 3-5 m³ / min.

4. The coiled tubing, bullheaded fracturing method of claim 1, characterized in that: In step S5, the nozzle of the coiled tubing has a jet speed of 110-130 m / s.

5. The coiled tubing, bullheaded fracturing method of claim 1, characterized in that: In step S5, the test squeeze fluid is slick water, and the carrying fluid is active water.

6. The coiled tubing, bullheaded fracturing method of claim 1, characterized in that: In step S6, the coiled tubing continuously supplements liquid, and the displacement is 0.1-0.2 m³ / min.

7. The coiled tubing, bullheaded fracturing method of claim 1, characterized in that: The pumping system comprises a sand tank group, a slick water tank group, an active water tank group, a liquid supplement tank group, a sand mixing vehicle, a low-pressure manifold, a first fracturing vehicle group, a high-pressure manifold, a second fracturing vehicle group, a coiled tubing vehicle, and a blowout tank, wherein the active water tank group, the slick water tank group, and the sand tank group are connected with the inlet of the sand mixing vehicle, the outlet of the sand mixing vehicle is connected with the inlet of the low-pressure manifold, the low-pressure manifold is respectively connected with the inlets of the first fracturing vehicles in the first fracturing vehicle group, the outlets of the first fracturing vehicles are all connected with the high-pressure manifold, the outlet of one of the first fracturing vehicles is also connected with the coiled tubing vehicle, the outlet of the high-pressure manifold is connected with the annulus, and the outlet of the coiled tubing vehicle is connected with the coiled tubing; the liquid supplement tank group is connected with the coiled tubing vehicle through the second fracturing vehicle group; and the blowout tank is connected with the annulus.

8. The coiled tubing, bullheaded fracturing method of claim 7, characterized in that: The method further comprises a supplemental water tank, the supplemental water tank is connected with the inlet of one of the first fracturing vehicles, and the height of the supplemental water tank is higher than that of the first fracturing vehicle; in step S4, one of the first fracturing vehicles pumps the circulating fluid into the coiled tubing through the coiled tubing vehicle, and the displacement of the circulating fluid is 0.6-0.8 m³ / min; and in step S5, only the supplemental water tank supplies the test squeeze fluid to the first fracturing vehicle, and the displacement of the test squeeze fluid is greater than or equal to 0.5 m³ / min.

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