CN111119826A - Coiled tubing staged fracturing string and string fracturing method - Google Patents
Coiled tubing staged fracturing string and string fracturing method Download PDFInfo
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- CN111119826A CN111119826A CN201811294234.6A CN201811294234A CN111119826A CN 111119826 A CN111119826 A CN 111119826A CN 201811294234 A CN201811294234 A CN 201811294234A CN 111119826 A CN111119826 A CN 111119826A
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- 238000000034 method Methods 0.000 title claims abstract description 30
- 239000004576 sand Substances 0.000 claims abstract description 118
- 238000010276 construction Methods 0.000 claims abstract description 52
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/11—Perforators; Permeators
- E21B43/114—Perforators using direct fluid action on the wall to be perforated, e.g. abrasive jets
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/14—Obtaining from a multiple-zone well
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/267—Methods for stimulating production by forming crevices or fractures reinforcing fractures by propping
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Abstract
The invention provides a coiled tubing staged fracturing string which comprises a safety joint, a hydraulic ejector, a centralizer and a mechanical positioner, wherein the safety joint, the hydraulic ejector, the centralizer and the mechanical positioner are sequentially connected onto the coiled tubing, and a controllable switch type pulse sand blaster and a mechanical packer are further connected between the centralizer and the mechanical positioner. The coiled tubing staged fracturing string provided by the invention has the advantages of simple structure, rapid layer changing construction and high reliability and safety, and can be used for completing staged fracturing operation of a multi-stage multi-section sand blasting perforation, bottom hole sand mixing fracturing and annular space large-displacement fracturing on a compact oil-gas reservoir oil-gas well by lowering the string once, so that a complex fracture network can be formed, the swept volume of compact reservoir reconstruction is improved, the staged fracturing operation efficiency of the compact oil-gas reservoir is improved, the development cost is reduced, and the fracturing development effect is improved. The invention also provides a staged fracturing method for the staged fracturing string by using the coiled tubing.
Description
Technical Field
The invention relates to the technical field of underground fracturing operation, in particular to a coiled tubing staged fracturing string and a staged fracturing method using the same.
Background
In recent years, domestic and foreign researches show that the increase of the complexity of cracks in the fracturing construction process can effectively improve the yield of single wells of low-permeability oil and gas reservoirs and finally improve the recovery ratio of the oil and gas reservoirs. At present, volume fracturing is a main technical means for constructing a complex fracture network in unconventional shale gas reservoir development, natural fractures are continuously expanded and brittle rocks generate shear slippage in a hydraulic fracturing process by adopting an injection mode with large discharge capacity, large sand capacity, large liquid quantity and low sand ratio, and a fracture network with natural fractures and artificial fractures staggered with each other is formed. The general method for applying coiled tubing injection staged fracturing at home and abroad is to adopt a coiled tubing to put a string with a hydraulic injection tool in a horizontal well for casing well cementation and completion, and sand-adding, sand-blasting and perforating from the coiled tubing, and then sand-adding and fracturing the casing. And after one section of fracturing is finished, a section of sand plug is reserved in the sleeve for isolation, and the pipe column is dragged to the next section for sand blasting perforation and fracturing construction. The method adopts casing fracturing, and can realize large-scale fracturing. However, the sand plug is used for sectional isolation, a long horizontal section is needed, and the sand plug needs to be flushed out of a shaft by a coiled tubing after fracturing is completed. The process has the problems of long construction period, untimely backflow of fracturing fluid to pollute an oil layer, long horizontal section for sand filling, difficult washing of a sand plug and the like.
The other method is to adopt a fracturing string with a packer under the coiled tubing as an isolation method, for example, a coiled tubing staged sand blasting perforation casing fracturing string and a casing fracturing method with patent number 201210182455.0, wherein a staged tool adopts a mechanical coiled tubing fracturing packer, and casing fracturing is adopted, so that large-scale fracturing can be realized.
However, the two continuous oil pipe fracturing methods are common continuous sand adding, the cracks are pressed open by static pressure and then extend, the construction method is not easy to form a complex crack network, and the method has a certain limit on improving the recovery ratio of the compact oil-gas reservoir.
Disclosure of Invention
In order to solve the technical problems, the invention provides a coiled tubing staged fracturing string suitable for staged fracturing operation of various well types such as a vertical well, an inclined well, a horizontal well and the like of compact sandstone and a method for staged fracturing by using the fracturing string.
The invention relates to a coiled tubing staged fracturing string which comprises a safety joint, a hydraulic ejector, a centralizer and a mechanical positioner which are sequentially connected to a coiled tubing, wherein a controllable switch type pulse sand ejector and a mechanical packer are further connected between the centralizer and the mechanical positioner.
In one embodiment, the controllable switch type pulse sand blower comprises a central body, wherein a central body flow passage is arranged on the central body, the central body can slide along the axial direction of the pulse sand blower inside the controllable switch type pulse sand blower, a body flow passage corresponding to the central body flow passage is arranged on the pulse sand blower body, and the opening and closing of the controllable switch type pulse sand blower are controlled through the sliding of the central body along the axis of the pulse ejector. When the central body slides to the position where the central body runner opening is opposite to the sliding sleeve runner opening, the pulse sand blaster is in an open state, and at the moment, the lower end of the central body is in contact with the sealing seat on the pulse sand blaster body. When the central body slides to the position where the central body runner port and the body runner port are completely staggered, the controllable switch type pulse sand blower is in an open state, and at the moment, the limit step on the central body is contacted with the limit step on the pulse sand blower body.
In one embodiment, a guiding head is further connected to the tail end of the mechanical positioner in sequence to facilitate running of the tubular string in the well.
The coiled tubing staged fracturing string provided by the invention has the advantages of simple structure, rapid layer changing construction and high reliability and safety, and can be used for completing staged fracturing operation of a multi-stage multi-section sand blasting perforation, bottom hole sand mixing fracturing and annular space large-displacement fracturing composite mode on a compact oil-gas reservoir oil-gas well by lowering the string once, so that a complex fracture network can be formed, the swept volume of compact reservoir reconstruction is improved, the staged fracturing operation efficiency of the compact oil-gas reservoir is improved, the development cost is reduced, and the fracturing development effect is improved.
The invention also provides a staged fracturing method using the coiled tubing staged fracturing string, which comprises the following steps:
step one, putting a coiled tubing staged fracturing string into a well;
adjusting the well entry depth of the coiled tubing staged fracturing string, adjusting the hydraulic ejector to the position of a target layer and completing hydraulic perforation;
adjusting the staged fracturing tubular column of the continuous oil pipe, completing the setting of a mechanical packer after the pulse sand blaster is positioned above a perforation position, and opening the controllable switch type pulse sand blaster;
and fourthly, performing pulse sand adding fracturing and annular sand adding fracturing on the construction section, and closing the well to measure the pressure drop after the annular sand adding fracturing is finished.
Step five: after the pressure measurement is finished, performing reverse well washing for a week, then lifting the coiled tubing staged fracturing string to the next construction section, repeating the steps II, III and IV, and performing perforation, pulse sand adding fracturing and annular sand adding fracturing on the next construction section;
step six: and repeating the fifth step until the fracturing construction operation of the subsequent section is completed.
In one embodiment, in the fourth step, in the stage of pulse sand fracturing, in the early stage of pulse sand fracturing, a high-concentration sand-containing fracturing fluid with a sand ratio of 40% to 85% is injected into the coiled tubing, a sand-free fracturing base fluid is injected into the annulus, and in the later stage of pulse sand fracturing, a fracturing base fluid is injected into the coiled tubing to replace the fracturing base fluid for the sand-containing fracturing fluid in the coiled tubing.
In one embodiment, in the fourth step, in the annular sand fracturing stage, before the annular sand fracturing stage, the fracturing base fluid is injected into the coiled tubing, and the sand-containing fracturing fluid is injected into the annular large discharge amount. Preferably, high-concentration sand-containing fracturing fluid with a sand ratio of 15% -50% is injected into the annulus at a large discharge capacity, and fracturing base fluid is injected into the annulus at the later stage of annulus sand fracturing to replace the fracturing base fluid for the sand-containing fracturing fluid in the annulus.
In one embodiment, during the annular sand fracturing process, high-concentration sand-containing fracturing fluid is injected into the annular space in a large-discharge continuous stepped mode, and fracturing base fluid is injected into a continuous oil pipe in a variable-discharge or constant-discharge mode.
In one embodiment, the displacement amount of the fracturing base fluid is 1.2 to 1.4 times the volume of the wellbore at the later stage of the annular fracturing construction.
In one embodiment, before the pulse sand fracturing in the fourth step, pulse fracturing parameter optimization is further performed, according to the magnitude of the formation ground stress value and different conditions of stress difference, the magnitude of the net pressure required by formation fracture and steering is simulated, the combination mode of the pulse type and the pulse mode is reasonably determined, and the pulse time length and the pulse displacement combination are determined.
In one embodiment, the fracturing sand is applied to the pulse sand fracturing stage in a size of 40-100 meshes.
Compared with the prior art, the coiled tubing staged fracturing string provided by the invention has the advantages of simple structure, rapid layer changing construction, high reliability and safety of the string, simple and convenient staged fracturing method, capability of realizing the composite fracturing transformation of staged fixed-point jet perforation, pulse sand fracturing and annular sand fracturing of an oil-gas well by one-trip string, greatly improving the layering and staged transformation effects of a compact oil-gas reservoir, improving the complexity, the flow conductivity and the swept volume of a reservoir transformation crack, and greatly improving the fracturing yield-increasing effect of a fractured well.
The technical features described above can be combined in various technically feasible ways to produce new embodiments, as long as the object of the invention is achieved.
Drawings
The invention will be described in more detail hereinafter on the basis of non-limiting examples only and with reference to the accompanying drawings. Wherein:
FIG. 1 shows a schematic of a coiled tubing frac string configuration according to the present invention;
FIG. 2 shows a schematic view of the construction of the pulse blaster of FIG. 1;
FIG. 3 is a schematic view showing the structure of the pulse blaster of FIG. 2 in an open state;
FIG. 4 is a schematic structural view showing a closed state of the pulse blaster of FIG. 2;
FIG. 5 shows a schematic of the mechanical packer of FIG. 1;
FIG. 6 is a schematic diagram showing a variation pattern of annulus displacement in a rise-fall manner in an embodiment of the present invention;
FIG. 7 is a schematic diagram showing a change pattern of displacement of annulus volume up-down-up in an embodiment of the present invention;
fig. 8 shows a schematic diagram of a change pattern of the annular displacement of the embodiment of the invention, namely ascending-descending-ascending.
In the drawings, like components are denoted by like reference numerals. The figures are not drawn to scale.
Wherein the reference numerals are:
1. a coiled tubing; 2. a coiled tubing joint; 3. a safety joint; 4. a hydraulic ejector; 5. a centralizer; 6. a controllable switch type pulse sand blower; 7. a mechanical packer; 8. a mechanical positioner; 9. a guide head; 61. a central body; 62. a central body flow passage opening; 63. a body runner port; 64. a central body limit step; 65. a body limiting step; 66. a body seal seat; 67. a central body lower end; 71. an upper joint; 72. sealing the rubber cylinder; 73. a seat body; 74. slips; 75. a packer centralizing body; 76. a lower joint; 100. and fracturing the tubular column by stages through the coiled tubing.
Detailed Description
The invention will be described in further detail below with reference to the drawings and specific examples. It should be noted that, as long as there is no conflict, the embodiments and the features of the embodiments of the present invention may be combined with each other, and the technical solutions formed are within the scope of the present invention.
As shown in figure 1, the coiled tubing staged fracturing string 100 comprises a safety joint 3, a hydraulic ejector 4, a centralizer 5 and a mechanical positioner 8 which are sequentially connected to a coiled tubing 1, a controllable switch type pulse sand blaster 6 and a mechanical packer 7 are further connected between the centralizer 5 and the mechanical positioner 8, a guide head 9 is further arranged at the other end of the mechanical positioner 8, and all the components are connected through tubing threads.
As shown in fig. 2, fig. 3 and fig. 4, in an alternative embodiment, the controllable switch type pulse sand blower 6 includes a central body 61, a central body flow passage 62 is disposed on the central body 61, the central body 61 can slide along the axial direction of the controllable switch type pulse sand blower 6 inside the controllable switch type pulse sand blower 6, a body flow passage 63 corresponding to the central body flow passage 62 is disposed on the pulse sand blower body, and the opening and closing of the pulse sand blower is controlled by the sliding of the central body 61 along the axis of the controllable switch type pulse sand blower 6. When the center body 61 is slid to a position where the center body port 62 is opposite the body port 63, the controllably openable pulse blaster 6 is in an open position with the center body lower end 67 in contact with the seal seat 66 on the pulse blaster body. When the center body 61 slides to a position where the center body flow passage port 62 and the body flow passage port 63 are completely staggered, the controllable on-off type pulse sander 6 is in a closed state, and at this time, the center body limit step 64 on the center body 61 contacts with the body limit step 65 on the pulse sander body.
And a guide head 9 is also arranged at the tail end of the mechanical positioner 8, so that the pipe column can be conveniently put in.
The hydraulic ejector 4 and the mechanical packer 7 may be selected from those commonly used in the art. In this embodiment, as shown in fig. 5, the mechanical packer 7 includes a central pipe, a slip 74, a setting body 73 and a sealing rubber tube 72, the central pipe is provided with a setting track and a unsetting track, the slip 74, the setting body 73 and the sealing rubber tube 72 are installed on the central pipe, two ends of the central pipe are respectively connected with an upper joint 71 and a lower joint 76, and the lower joint 76 is connected with the slip 74 through a packer centralizing body 75.
The coiled tubing staged fracturing string provided by the invention has the advantages of simple structure, high tool reliability and safety, and good construction continuity, and the staged fixed-point jet perforation, pulse sand fracturing and annular sand fracturing combined fracturing transformation of an oil-gas well can be realized by lowering the string once, so that the construction time is saved, the construction cost is reduced, the layering and staged transformation effects of a compact oil-gas reservoir are greatly improved, the complexity, the flow conductivity and the swept volume of a reservoir transformation crack are improved, the fracturing yield-increasing effect of a fracturing well can be greatly improved, and the oil field development effect is improved.
The invention also provides a staged fracturing method using the coiled tubing staged fracturing string in the embodiment, which comprises the following steps:
selecting corresponding tools to assemble a coiled tubing staged fracturing string for construction according to the specification of a construction well, and then putting the assembled coiled tubing staged fracturing string into the well;
adjusting the well entry depth of the coiled tubing staged fracturing string, adjusting the hydraulic ejector to the position of a target layer and completing perforation;
adjusting the coiled tubing staged fracturing string to enable the controllable switch type pulse sand blaster to be positioned above the perforation position, then completing mechanical packer setting, and opening the controllable switch type pulse sand blaster;
and fourthly, performing pulse sand adding fracturing and annular sand adding fracturing on the construction section, and closing the well to measure the pressure drop after the annular sand adding fracturing is finished.
Step five: after the pressure measurement and the pressure reduction are finished, performing reverse well washing, then lifting the coiled tubing staged fracturing string to the next construction section, repeating the steps II, III and IV, and performing perforation, pulse sand adding fracturing and annular sand adding fracturing on the next construction section;
step six: repeating the fifth step until the fracturing construction operation of the subsequent section is completed;
step seven: and (5) taking out the coiled tubing staged fracturing string, and testing the fracturing well for production.
The specific implementation steps can adopt the following technical scheme:
(1) evaluation of key reservoir parameters
The method comprises the longitudinal and transverse distribution characteristics, lithology, whole rock mineral components, physical properties, rock mechanical parameters, three-dimensional ground stress characteristics, temperature and pressure and the like of a reservoir. The evaluation method of the related reservoir parameters can be determined by comprehensively applying the methods such as earthquake, well logging, well testing, pilot hole well core indoor test and the like.
(2) Determination of partial pressure interval
For compact sandstone oil and gas reservoirs, a well cementation and completion mode is generally adopted, so that the stability of a well bore is not influenced. Under the conditions of well cementation and completion, the number of measure reconstruction sections and specific depth data need to be determined according to the quality of well cementation, the size of an interlayer and the construction position.
(3) Oil and gas reservoir geological model establishment and production history fitting
On the basis of the determination of the partial pressure interval in the step (2), a fine geological model, particularly the identification and fine drawing of natural fractures, is established by using common geological modeling software PETROL. If the well is produced or tested, historical fitting of yield or pressure and the like can be carried out by using production or test data, and therefore information of stratum key parameters such as effective permeability, skin coefficient and the like of each construction interval is determined.
(4) Optimization of fracture parameter system
And (3) introducing the geological model parameters into common dense hydrocarbon reservoir yield prediction simulation software ECLIPSE, and setting artificial fractures and natural fracture systems with different modified intervals according to an equivalent conductivity method. And then, simulating the pressed output dynamics of different fractured half-fracture lengths, fracture flow conductivity, fracture spacing and different fracture distribution modes according to an orthogonal design method, and preferably selecting the optimal fracture parameters of each modified interval.
(5) Pulse sand fracturing and optimization of large-scale fracturing construction parameters
Optimizing pulse sand fracturing parameters, simulating the numerical value of net pressure required by stratum fracture and steering according to the numerical value of stratum ground stress and different conditions of stress difference, reasonably determining the combination mode of pulse types and pulse modes, and determining the combination of pulse time and pulse discharge capacity to complicate fractures as much as possible.
In order to realize the optimized fracture parameters of each interval in the step (4), common commercial simulation software for fracturing design, such as STIMPLAN, Fracpro PT and the like, is applied to simulate the fracture length, the flow conductivity and the like under different fracturing construction parameters, and the optimal fracturing construction parameter combination of each modified interval is preferably selected.
(6) Coiled tubing truck group equipment and tubular column connection well
And (3) selecting a proper coiled tubing truck set (comprising pressure grade, pipe diameter, coiled tubing length and the like) according to the fracturing well data and the construction interval depth requirement determined in the step (2), assembling a staged string tool on the ground to form the staged fracturing string of the coiled tubing, then entering the well according to the construction requirement, and carrying out configuration work of fracturing equipment, fracturing materials, construction liquid and the like according to the fracturing construction design.
(7) Pipe column depth correction, perforation and trial extrusion test
After the coiled tubing staged fracturing string 100 is completely drilled, the mechanical positioner 8 is used for performing string depth correction, and the depth of the string is adjusted according to the depth correction result, so that the hydraulic ejectors 4 are respectively aligned to the target intervals to perform hydraulic jet perforation. After the perforation is finished, the annular space of the sleeve is closed, active water is injected into the coiled tubing 1 at a small displacement, the perforation is confirmed to be perfect, and the stratum is pressed open to absorb the liquid.
(8) Setting packer
Adjusting the coiled tubing staged fracturing string 100 to enable the controllable switch type pulse sand blaster 6 to be positioned above a perforation position, then completing setting of a mechanical packer 7, and opening the controllable switch type pulse sand blaster 6;
(9) the first section of pulse sand fracturing construction:
after the mechanical packer 7 is set, the continuous oil pipe 1 is pressed down, the controllable switch type pulse sand blaster 6 is opened, the slip 74 of the mechanical packer 7 is opened and supported on the inner wall of the casing, and the sealing rubber sleeve 72 of the mechanical packer 7 is compressed and expanded along with the increase of the pressing force to seal the annular space of the oil casing. At the moment, high-concentration sand-containing fracturing fluid is injected into the coiled tubing 1, sand-free fracturing base fluid is injected into the annular space, different pulse modes and annular space staged variable displacement injection are carried out according to the construction parameters optimized in the step (5), the stratum is subjected to pulse fracturing, and cracks are steered to form a multi-crack system. Preferably, the sand content of the high-concentration sand-containing fracturing fluid injected at the stage is 40-85%.
Preferably, the displacement of the coiled tubing 1 is 0.4-1.5 square/minute and the displacement of the annulus is 0-7 square/minute. The fracturing sand with the grain size of 40-100 meshes is applied in the stage, more preferably, the fracturing sand with the grain size of 70-100 meshes is applied in the stage, and 10-30% of 40-70 meshes of fracturing sand can be added to form the fracturing sand with the composite grain size according to the requirement.
And in the later stage of pulse sand-adding fracturing, injecting a sand-free fracturing base fluid into the continuous oil pipe, and completely replacing the sand-containing fracturing fluid in the continuous oil pipe 1 with the sand-free fracturing base fluid.
Specifically, the annular displacement can be changed spirally according to the construction parameters optimized in the step (5), namely, the displacement is changed from large to small and then changed from small to large or changed in a plurality of cycles. In the actual construction process, the combination of the pulse time and the pulse displacement can be optimized according to the specific fractured well stratum conditions, as shown in fig. 6, 7 and 8, fig. 6 is a change mode of annular displacement in ascending-descending, fig. 7 is a change mode of annular displacement in ascending-descending-ascending-vertical-descending-ascending, and fig. 8 is a change mode of annular displacement in ascending-descending-ascending. Different change modes are selected according to specific construction parameters, so that high-concentration sand plugs can be formed in the cracks for multiple times, the net pressure in the cracks is increased, the cracks are turned for multiple times, and a complex crack network is formed.
(10) First-stage annular sand fracturing construction
At this stage, a sand-free fracturing fluid base fluid is injected into the continuous oil pipe 1, and a high-concentration sand-containing fracturing fluid with a sand ratio of 15-50% is injected into the annular large discharge volume. And (4) performing large-displacement (namely the displacement is more than 4 square/minute) fracturing construction according to the construction parameters optimized in the step (5), so that the fracture can be extended as far as possible, and the reconstruction volume of the fracture is increased. And at the later stage of annular fracturing, injecting sand-free fracturing base fluid into the annulus, completely replacing the high-concentration sand-containing fracturing fluid in the shaft with the sand-free fracturing base fluid, wherein the displacement amount is 1.2-1.4 times of the volume V of the shaft, closing the well, performing pressure diffusion, and measuring the pressure drop.
In the stage, annular large-displacement continuous stepped injection of sand-containing fracturing fluid can be performed, and the continuous oil pipe variable-displacement injection of fracturing base fluid can be performed, so that discontinuous sand-containing fluid sections can be formed in the cracks, discontinuous support is finally formed, and the flow conductivity of the cracks is increased; or the continuous supporting fracture can be formed by injecting the fracturing base fluid into the continuous oil pipe at constant displacement. Therefore, on the basis of forming complex cracks by pulse sand fracturing, the space of the cracks is extended, and the reconstruction volume of the cracks is increased.
And after the pressure drop to be measured is finished, performing backwashing for one circle, wherein the well flushing liquid amount is 1.5-2.0 times of the volume of the shaft.
(11) Deblocking packer and replacing second section construction
And (4) lifting the continuous oil pipe 1, unsealing the mechanical packer 7, continuously lifting the continuous oil pipe 1 to a second section of target layer, and performing segmented composite fracturing reconstruction construction on the second layer section again according to the steps (7), (8), (9) and (10).
(12) Subsequent interval fracturing operation
And (5) repeating the step (11) to finish the subsequent fracturing construction operation.
(13) Last replacement operation
And adopting over-displacement operation, selecting slickwater as displacement liquid after the whole well construction is finished, wherein the displacement amount is the volume V of the current section of the shaft and is added by 2-5 square.
(14) And closing the well and measuring the pressure drop.
And (5) performing well closing and pressure drop measurement according to the construction design.
(15) Pulling out construction pipe column
And after the pressure drop measurement is finished, backwashing for one circle, wherein the flushing fluid amount is 1.5-2.0 times of the volume of the shaft, then lifting the coiled tubing 1, unsealing the mechanical packer 7, continuously lifting the coiled tubing 1, and lifting the coiled tubing staged fracturing string 100.
(16) And testing the fracturing well for production.
According to the staged fracturing method of the coiled tubing staged fracturing string, temporary plugging of the proppant in the crack is caused by controlling the continuous reciprocating change of the well bottom sand concentration through low construction displacement, the rising of the net pressure in the instantaneous crack is realized, a complex crack net with a plurality of cracks is formed, then annular large-displacement sand adding fracturing is performed, the complex crack net is extended, and the fracturing volume is improved to the maximum extent. After one-section fracturing construction, the packer is dragged by lifting the continuous oil pipe, multi-stage and multi-section fracturing transformation of a fracturing well is realized, a plurality of complex fracture networks are formed, swept volume of tight reservoir transformation is improved, staged fracturing operation efficiency of a tight oil and gas reservoir is improved, development cost is reduced, and fracturing development benefit and final recovery ratio of the oil and gas reservoir are improved.
It will thus be appreciated by those skilled in the art that while the invention has been described with reference to a preferred embodiment, various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In particular, the technical features mentioned in the embodiments can be combined in any way as long as there is no structural conflict. It is intended that the invention not be limited to the particular embodiments disclosed, but that the invention will include all embodiments falling within the scope of the appended claims.
Claims (9)
1. The utility model provides a coiled tubing staged fracturing tubular column, is including the safety joint, hydraulic ejector, centralizer and the mechanical locator of connecting gradually on coiled tubing, its characterized in that still be connected with controllable switch formula pulse sand blaster and mechanical type packer between the centralizer with the mechanical locator.
2. The coiled tubing staged fracturing string as claimed in claim 1, wherein the controlled switch type pulse sand blaster comprises a central body, a central body runner port is arranged on the central body, the central body can slide along the axial direction of the controlled switch type pulse sand blaster inside the controlled switch type pulse sand blaster, a body runner port corresponding to the central body runner port is arranged on the pulse sand blaster body, and the opening and closing of the controlled switch type pulse sand blaster are controlled by the sliding of the central body along the axis of the controlled switch type pulse sand blaster.
3. A fracturing method using the coiled tubing staged fracturing string of claim 1 or 2, comprising the steps of:
step one, putting a coiled tubing staged fracturing string into a well;
adjusting the well entry depth of the coiled tubing staged fracturing string, adjusting the hydraulic ejector to the position of a target layer and completing hydraulic perforation;
adjusting the coiled tubing staged fracturing string to enable the controllable switch type pulse sand blaster to be positioned above the perforation position, then completing mechanical packer setting, and opening the controllable switch type pulse sand blaster;
fourthly, performing pulse sand adding fracturing and annular sand adding fracturing on the construction section, and closing the well to measure the pressure drop after the annular sand adding fracturing is finished;
step five: after the pressure measurement is finished, performing reverse well washing for a week, then lifting the coiled tubing staged fracturing string to the next construction section, repeating the steps II, III and IV, and performing perforation, pulse sand adding fracturing and annular sand adding fracturing on the next construction section;
step six: and repeating the fifth step until the fracturing construction operation of the subsequent section is completed.
4. The fracturing method according to claim 3, wherein in the fourth step, in the pulse sand fracturing stage, in the early stage of the pulse sand fracturing, the high-concentration sand-containing fracturing fluid is injected into the continuous oil pipe, the sand-free fracturing base fluid is injected into the annular space, and in the later stage of the pulse sand fracturing, the fracturing base fluid is injected into the continuous oil pipe to replace the fracturing base fluid for the sand-containing fracturing fluid in the continuous oil pipe.
5. The fracturing method according to claim 3 or 4, wherein in the fourth step, in the pulse sand fracturing stage, in the pulse sand fracturing period, the fracturing base fluid is injected into the annular space, and the displacement of the annular space is changed according to a designed pulse mode.
6. The fracturing method according to claim 4, wherein in the fourth step, in the annular sand fracturing stage, in the early annular sand fracturing stage, the fracturing base fluid is injected into the coiled tubing, the high-concentration sand-containing fracturing fluid is injected into the annular large discharge amount, and in the later annular sand fracturing stage, the fracturing base fluid is injected into the annular to replace the fracturing base fluid for the sand-containing fracturing fluid in the annular.
7. The fracturing method of claim 6, wherein the displacement of the fracturing base fluid is 1.2 to 1.4 times the wellbore volume at the later stages of the annular fracturing construction.
8. The fracturing method of claim 5, wherein before the pulse sand fracturing in the fourth step, pulse fracturing parameter optimization is needed, the numerical value of net pressure required by stratum fracture and steering is simulated according to the numerical value of the stratum ground stress and different conditions of stress difference, the combination mode of pulse type and pulse mode is reasonably determined, and the pulse time length and pulse displacement combination are determined.
9. The fracturing method according to claim 3 or 4, wherein in the fourth step, in the pulse sand fracturing stage, the fracturing sand is applied to be 40-100 meshes.
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