CN111927423B - Shale sand fracturing pump-stopping fracturing steering method - Google Patents
Shale sand fracturing pump-stopping fracturing steering method Download PDFInfo
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- CN111927423B CN111927423B CN202010927930.7A CN202010927930A CN111927423B CN 111927423 B CN111927423 B CN 111927423B CN 202010927930 A CN202010927930 A CN 202010927930A CN 111927423 B CN111927423 B CN 111927423B
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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 DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B43/261—Separate steps of (1) cementing, plugging or consolidating and (2) fracturing or attacking the formation
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
Abstract
The invention provides a shale sand fracturing pump-stopping fracturing steering method, which aims at a stratum with over-high torsional friction resistance in a shale fracturing process and comprises the following steps: pumping a sand-carrying liquid to polish a formation crack, and monitoring the pumping pressure; when the pumping pressure rises to reach the wellhead pressure limiting, the slickwater is used for replacing the sand-carrying liquid for pumping; stopping the pump to reduce the pump injection displacement from the first displacement to zero and keeping the pump injection displacement for a preset time period; starting a pump to pump preposed liquid into the well and quickly increasing the pumping displacement to a first displacement; pumping and injecting the sand-carrying liquid again for fracturing construction after the preposed liquid pump finishes injecting; opening a new crack under the action of energy pulses generated by stopping and starting the pump and pressure difference generated by the sedimentation of the propping agent, so that the crack is turned; repeating the above steps to complete the fracturing construction; the first displacement is designed construction displacement or maximum construction displacement under a wellhead pressure limiting condition. The invention has the advantages of no need of adding temporary plugging materials, solving the problem of overhigh distortion friction resistance, ensuring the construction quality and the like.
Description
Technical Field
The invention relates to the technical field of shale reservoir fracturing, in particular to a shale sand fracturing pump-stopping fracturing steering method.
Background
With the deep development of oil and gas exploration, the fracture transformation object is not limited to a conventional oil and gas reservoir and gradually enters an unconventional oil and gas reservoir, wherein shale oil and gas are typical representatives of the unconventional oil and gas reservoir. In recent years, the scale of domestic shale oil and gas exploration and development is increased year by year, the number of fracturing wells and the number of stages are correspondingly increased year by year, the domestic shale oil and gas fracturing technology is greatly developed, but with the improvement of the shale oil and gas fracturing technology, some technical difficulties also exist. The method has the problems of torsional friction resistance of a conventional reservoir in the shale fracturing process (namely that a certain included angle exists between an artificial fracture and a natural fracture, the width of the joint of the two fractures is generally narrowed, and a propping agent is difficult to pass, so that the bottom hole pressure (pump pressure) is rapidly increased), and if the torsional friction resistance is too high in the shale fracturing process, the method generally adopts a low sand concentration (40-120 kg/m) 3 ) Sanding, but with low sand concentration (40-60 kg/m) in individual intervals 3 ) After entering, the sand-carrying fluid has abnormally high construction pressure (reaching the pressure limiting of a well head), and can not be subjected to sand adding and polishing, so that direct sand blocking can be caused seriously and even; in the fracturing process, the bottom hole pressure (pumping pressure) is abnormally increased after a certain sand concentration enters a stratum, so that the designed sand adding amount cannot be finished subsequently; at present, a multi-cluster perforation technology is generally adopted for shale fracturing modification (at present, yu areas are generally 3-13 clusters, and further increase of the number of perforation clusters is not excluded), the purposes of forming a fracturing network, reducing casing rate and reducing fracturing cost after optimizing the length of a section are achieved, however, the multi-cluster perforation is generally only used for feeding liquid into a plurality of clusters in the actual fracturing process, the liquid feeding condition of all the perforation clusters is less, and in addition, the casing deformation phenomenon exists in the shale fracturing at present, so that the fracturing section is longer, and a turning measure needs to be taken for a long section and a casing deformation section in the shale fracturing process, so that the whole modification section is modified as far as possible, the maximum reservoir productivity is released, and remarkable economic development benefits are obtained. Therefore, in order to ensure that the fracturing construction meets the design requirements and that the long section and the casing transformation section are fully transformed, a new steering technology is needed to solve the problems.
The patent numbers are: 201911036571X, entitled "method for determining real-time steering fracturing parameters based on composite temporary plugging system", discloses that temporary plugging of perforation holes and fractures of different scales is realized by using a composite temporary plugging system comprising soluble temporary plugging balls and temporary plugging particles, and simultaneously, data analysis such as geological parameters, construction pressure, microseism real-time monitoring and the like is integrated to form real-time optimization of the addition amount, the addition time and the addition frequency of a composite temporary plugging material, realize uniform modification of a horizontal segment, and improve the complexity of a fracturing network. However, this invention requires the addition of a temporary plugging material.
The patent numbers are: 2019107680013, a chinese patent entitled "a reverse flow-limiting intra-segment clustering fracturing method and application" discloses that by designing a single well fracturing perforation scheme, the success rate of segmented multi-cluster temporary plugging diversion fracturing is improved, the packing effectiveness of temporary plugging diversion fracturing is improved, the number of cracks is reliably increased, infinite layered fracturing reconstruction is realized, and the purpose of uniform reservoir reconstruction is achieved; the shaft is designed to be large in drift diameter, so that the requirement of large-displacement transformation of a reservoir is met; the whole drift diameter of the shaft after the measures is taken, so that the subsequent shaft operation is convenient; the invention is suitable for the measure reconstruction of vertical wells, directional wells and horizontal wells, and the measure reconstruction of newly built wells and repeatedly reconstructed wells; the soluble temporary plugging agent used in the invention is completely discharged out of the ground after being pressed, thereby effectively reducing the damage to the reservoir. However, this invention requires the addition of a temporary blocking agent.
The patent numbers are: 2019102621057, entitled "a novel temporary plugging diversion fracturing method", discloses a temporary plugging diversion fracturing method, which comprises the following steps: (1) perforating: carrying out dense perforation by using an equal-aperture bullet to obtain a uniform aperture; (2) injecting a temporary plugging agent: and injecting the temporary plugging agent into the same perforation section for three times. The method combines a novel perforation mode with temporary plugging agents with different particle sizes and different fracturing fluid viscosities and discharge capacities, and simultaneously, the temporary plugging agents with different particle sizes are added in a mode and are matched with the fracturing fluid at a time, so that an organic whole is formed. However, this invention requires the addition of a temporary blocking agent.
Disclosure of Invention
The present invention aims to address at least one of the above-mentioned deficiencies of the prior art. For example, one of the purposes of the invention is to provide a pump-stopping fracturing steering method which can solve the problems that the distortion friction is too high, sand cannot be added and even sand is blocked in the shale sand adding fracturing process.
In order to achieve the purpose, the invention provides a pump-stopping fracturing steering method for shale sand fracturing. The method aims at the problem that a certain amount of 40-120 kg/m is injected into a formation pump in the shale fracturing process 3 The pumping pressure rises after carrying the sand liquid and approaches the pressure limiting of the well head, and the pumping displacement is lower than 8m 3 A/min formation, the fracture diversion method may include the steps of: pumping a sand-carrying liquid into a wellhead to polish a formation crack, and monitoring the change condition of pumping pressure in the pumping process; at a rate of change of pump filling pressure with a slope>When the pressure reaches the wellhead pressure limit, slickwater is used for replacing the sand-carrying fluid to carry out pump injection so as to replace the sand-carrying fluid in the shaft into the stratum; after the replacement is finished, stopping the pump to reduce the pump injection displacement from the first displacement to zero and keeping for a preset time period to settle the propping agent in the sand-carrying liquid; starting the pump again, keeping the liquid supply stable, pumping the preposed liquid into the wellhead and quickly increasing the pumping displacement to the first displacement within 2 min; pumping and injecting the sand-carrying liquid again for fracturing construction after the preposed liquid is pumped and injected; opening a new crack under the action of exciting pressure generated by the displacement reduction and displacement increase and pressure difference of 2-5 MPa generated by the sedimentation of the proppant in the crack, and realizing crack steering; repeating the above steps until the fracturing construction is completed; the first displacement is designed construction displacement or maximum construction displacement under a wellhead pressure limiting condition.
In one exemplary embodiment of an aspect of the present invention, the predetermined period of time may be 10 to 40min.
In an exemplary embodiment of an aspect of the present invention, the pump injection amount of the pre-liquid may be 50 to 90m 3 。
In an exemplary embodiment of an aspect of the invention, the proppant in the sand-carrying fluid may have a similar effect as a temporary plugging agent to plug a fracture after settling.
The invention also aims to provide a pump-stopping fracturing steering method which can solve the problems that the well bottom pressure is abnormally increased, the sand is difficult to add and the designed sand adding amount cannot be completed in the shale sand adding fracturing process.
The invention also provides a pump-stopping fracturing steering method for shale sand fracturing. The method aims at the problem that a certain amount of 40-120 kg/m is pumped into a stratum in the shale fracturing process 3 The bottom hole pressure after the sand carrying fluid changes at a slope rate>0, rising, and subsequently failing to complete the formation with the designed sand addition, the fracturing diversion method can comprise the following steps: injecting a sand-carrying fluid into a wellhead pump to polish a formation crack, and monitoring the change condition of the pumping pressure in the pumping process; at a rate of change of pump filling pressure with a slope>When the lifting rate is increased and the pressure is limited when the well head is reached, slickwater is used for replacing the sand-carrying fluid to carry out pump injection so as to replace the sand-carrying fluid in the shaft into the stratum; after the replacement is finished, stopping the pump to reduce the pump injection displacement from the first displacement to zero and keeping for a preset time period to settle the propping agent in the sand-carrying liquid; starting the pump again, keeping the liquid supply stable, pumping the preposed liquid into the wellhead, rapidly increasing the pumping displacement to the first displacement within 2min, and opening a new crack under the action of the exciting pressure generated by the displacement reduction and displacement increase and the pressure difference generated by the proppant sedimentation in the crack of 2-5 MPa to realize the crack steering; after the preposed liquid pump injection is finished, adding silt to polish the newly opened crack and adding a propping agent to prop the crack; repeating the above steps until the fracturing construction is completed; the first displacement is designed construction displacement or maximum construction displacement under a wellhead pressure limiting condition.
In an exemplary embodiment of another aspect of the present invention, the predetermined period of time may be 10 to 40min.
In an exemplary embodiment of another aspect of the present invention, the pump shot of the pad may be 50 to 90m 3 。
In an exemplary embodiment of another aspect of the present invention, the silt may be added in an amount of 1 to 20t, the particle size of the silt may be 70 to 140 mesh, and the particle size of the large-particle proppant may be 40 to 70 mesh.
In an exemplary embodiment of another aspect of the invention, the proppant in the sand-carrying fluid may act like a temporary plugging agent to plug the fracture after settling.
The invention also aims to provide a pump-stopping fracturing steering method which can solve the problems of insufficient fracturing or abnormal construction pressure caused by inaccurate adding amount of the temporary plugging agent in the casing-changed well section or long-section fracturing transformation in the shale sand fracturing process, difficult or impossible fracturing of subsequent well section fracturing construction and fracturing transformation only by lowering a bridge plug.
The invention further provides a pump-stopping fracturing steering method for shale sand fracturing. The method aims at the stratum with a casing change well section or a long section in the shale fracturing process, the length of the casing change well section or the long section is more than 60m, and the stress difference value is 2-5 MPa, and the fracturing steering method can comprise the following steps: determining the pumping quantity of the sand-carrying fluid as a first volume according to the number of the first opened perforation clusters, and pumping the sand-carrying fluid with the first volume into the wellhead by using the first displacement to perform fracturing modification; after the sand-carrying fluid is pumped, slickwater is used for replacing the sand-carrying fluid to pump and inject the residual sand-carrying fluid in the shaft into the stratum; after the replacement is finished, stopping the pump to reduce the pump injection displacement from the first displacement to zero and keeping for a preset time period to settle the propping agent in the sand-carrying liquid; starting the pump again, pumping the sand-carrying liquid with the first volume into the wellhead, rapidly increasing the pumping displacement to the first displacement within 2min, and opening a new crack under the action of exciting pressure generated by the displacement reduction and displacement increase and pressure difference of 2-5 MPa generated by the sedimentation of the proppant in the crack to realize crack steering; repeating the above processes until the casing deformation well section or the long section is completely transformed; the first displacement is designed construction displacement or maximum construction displacement under a wellhead pressure limiting condition.
In an exemplary embodiment of still another aspect of the present invention, the predetermined period of time may be 10 to 40min.
In an exemplary embodiment of the other aspect of the invention, the number of the perforation clusters is more than 3 clusters, the first volume accounts for 1/N of the total liquid volume designed for the fracturing construction of the section, and N is the fracturing times of the section.
In an exemplary embodiment of yet another aspect of the invention, the proppant in the sand-carrying fluid may act like a temporary plugging agent to plug the fracture after settling.
Compared with the prior art, the beneficial effects of the invention can comprise at least one of the following:
(1) The method can effectively solve the problems of over-high distortion friction resistance and insufficient seam width caused by natural crack development, and can also avoid the conditions that the temporary plugging material is added too little, the reconstruction is not in place due to ineffective plugging and the construction pressure is abnormal due to excessive plugging holes, the fracturing construction of the subsequent well section is difficult or impossible, and the fracturing can be continued only by adopting a blowout mode aiming at the casing deformation well section;
(2) The fracturing construction method is convenient for field application, new complex conditions (construction time is prolonged due to overhigh pressure and overlow discharge capacity, sand blocking and blowout) cannot be caused to fracturing construction, the overall construction progress is influenced, and from the economic point of view, additional fracturing materials do not need to be added, and a bridge plug (a segmenting tool) does not need to be put into a set variable section or a long section (small stress difference), so that the fracturing transformation cost is reduced.
Detailed Description
Hereinafter, the shale sand fracturing pump-stop fracturing diversion method of the invention will be described in detail with reference to exemplary embodiments.
The invention provides a shale sand fracturing pump-stopping fracturing steering method.
In an exemplary embodiment of the invention, the shale sand fracturing pump-stopping fracturing steering method aims at injecting a certain amount of 40-120 kg/m into a stratum pump in the shale fracturing process 3 The pumping pressure rises after carrying the sand liquid and approaches the pressure limiting of the well head, and the pumping displacement is lower than 8m 3 A/min formation, the fracture diversion method may include the steps of: pumping a sand-carrying liquid into a wellhead to polish a formation crack, and monitoring the change condition of pumping pressure in the pumping process; at a rate of change of pump filling pressure with a slope>And 0, under the condition of pressure limitation when the pressure rises and reaches a wellhead, slickwater is used for replacing the sand-carrying fluid to carry out pump injection so as to replace the sand-carrying fluid in the shaft into the stratum. Here, the time-dependent change curve of the pumping pressure can be approximately seen as a straight line in a short period of time, and thus the rate of change of the pressure can be expressed by the rate of change of the pumping pressure with time. In order to ensure that the pumping pressure does not exceed the pressure limiting of the wellhead, measures for reducing the pumping displacement can be taken in the pumping process. After the replacement is finishedStopping the pump to reduce the pump injection displacement from the first displacement to zero and keeping the pump injection displacement for a preset time period to settle the propping agent in the sand-carrying liquid; starting the pump again, keeping the liquid supply stable, pumping the preposed liquid into the wellhead and quickly increasing the liquid to the first discharge capacity within 2 min; pumping and injecting the sand-carrying liquid again for fracturing construction after the preposed liquid is pumped and injected; opening a new crack under the action of exciting pressure generated by displacement reduction and displacement increase and pressure difference of 2-5 MPa generated by proppant sedimentation in the crack, and realizing crack steering; repeating the above steps until the fracturing construction is completed; the first displacement is designed construction displacement or maximum construction displacement under a wellhead pressure limiting condition. Specifically, the construction curve of the shale fracturing device generally presents the characteristics of high pumping pressure, low discharge capacity and low sand concentration when the torsional friction resistance is too high in the shale fracturing process. The natural fractures may develop at a certain distance from the wellbore most of the time, and the construction pump pressure will rise rapidly or even sand blocking will occur after the low sand concentration slug enters the formation for a certain amount of liquid. Here, the rapid rise of the construction pump pressure may be 10 mpa in 1 minute or several tens mpa in several seconds. After the characteristics appear, slick water is used for replacing the sand carrying fluid to replace the low-sand-concentration sand carrying fluid in the shaft to enter the stratum. The concentration of the sand-carrying fluid may be any concentration of sand, and further, the concentration of the sand-carrying fluid may be 40 to 120kg/m 3 . And after the displacement is finished, stopping pumping to reduce the construction displacement to 0. For example, the predetermined time period may be 10 to 40min, and further, the predetermined time period may be 20 to 30min. The sand carrying fluid comprises a propping agent and a working fluid, and after the pump is stopped, the propping agent in the sand carrying fluid can generate an effect similar to a temporary plugging agent to plug the crack after sedimentation. And the pump is started again to pump the front liquid into the stratum, and the stratum is pressed open to form enough volume in the stratum. When the preposed liquid is pumped, the pumping displacement is quickly increased to the designed construction displacement or the maximum construction displacement under the condition of wellhead pressure limiting within 2min under the condition of ensuring stable liquid supply. The pump injection amount of the front liquid can be 50-90 m 3 . And finally, pumping and injecting the sand carrying liquid again for fracturing construction. And repeating the processes until the fracturing construction is completed.
In another exemplary embodiment of the inventionIn the embodiment, the shale sand fracturing pump-stopping fracturing steering method aims at that a certain amount of 40-120 kg/m is pumped into a stratum pump in the shale fracturing process 3 The bottom hole pressure after the sand carrying liquid changes at the slope rate>0, rising, and subsequently failing to complete the formation with the designed sand addition, the fracturing diversion method can comprise the following steps: pumping a sand-carrying liquid into a wellhead to polish a formation crack, and monitoring the change condition of pumping pressure in the pumping process; at a rate of change of pump filling pressure with a slope>When the pressure reaches the wellhead pressure limit, slickwater is used for replacing the sand-carrying fluid to carry out pump injection so as to replace the sand-carrying fluid in the shaft into the stratum; after the replacement is finished, stopping the pump to reduce the pump injection displacement from the first displacement to zero and keeping for a preset time period to settle the propping agent in the sand-carrying liquid; starting the pump again, keeping the liquid supply stable, pumping the preposed liquid into the wellhead, rapidly increasing the pumping displacement to the first displacement within 2min, and opening a new crack under the action of the exciting pressure generated by the displacement reduction and displacement increase and the pressure difference generated by the proppant sedimentation in the crack of 2-5 MPa to realize the crack steering; after the pre-liquid pumping is finished, adding silt to polish the newly opened crack and adding a large-particle-size propping agent to prop the crack after the pre-liquid pumping is finished; repeating the above steps until the fracturing construction is completed; the first displacement is designed construction displacement or maximum construction displacement under a wellhead pressure limiting condition. Specifically, when the bottom hole pressure (pump pressure) rises abnormally after a certain sand concentration enters the stratum, and consequently the designed sand adding amount cannot be finished, slickwater is used for replacing the sand carrying liquid in the shaft to enter the stratum. The concentration of the sand-carrying liquid can be 40-120 kg/m 3 Furthermore, the concentration of the sand carrying liquid can be 40-60 kg/m 3 . Here, in order to guarantee the effect, the propping agent is settled at the seam of the artificial crack, and the slippery water is not suitable for being replaced excessively. The pump is stopped to reduce the construction displacement to 0 and the construction displacement is kept for 10-40 min, for example, the preset time period can be 10-40 min, and further, the preset time period can be 20-30 min. In the time period, after the proppant in the sand carrying liquid is settled, the effect similar to that of a temporary plugging agent can be generated to plug the crack. And the pump is started again to inject the preposed liquid, and the discharge capacity is quickly increased to the designed construction discharge capacity or the maximum construction discharge capacity under the condition of wellhead pressure limiting. Priming of liquidsThe amount may be 50 to 90m 3 . And adding silt (polishing the eyelet friction and the distortion friction of a newly opened artificial crack and filling a natural crack) after the preposed liquid pump injection is finished, and then adding a large-particle-size propping agent for propping until the fracturing construction is finished, wherein the adding amount of the silt can be 1-20 t, the particle size of the silt can be 70-140 meshes, and the particle size of the large-particle-size propping agent can be 40-70 meshes.
In yet another exemplary embodiment of the present invention, a shale sand fracturing pump-stopped fracturing diversion method for a stratum with a length of more than 60m and a stress difference of 2-5 MPa in a shale fracturing process, which requires perforation by using a multi-cluster perforation technology, is used for a stratum with a length of more than 60m and a stress difference of 2-5 MPa, and may include the steps of: determining the pumping quantity of the sand-carrying fluid as a first volume according to the number of the first opened perforation clusters, and pumping the sand-carrying fluid with the first volume into the wellhead by using the first displacement to perform fracturing modification; after the sand-carrying fluid is pumped, slickwater is used for replacing the sand-carrying fluid to pump and inject the residual sand-carrying fluid in the shaft into the stratum; after the replacement is finished, stopping the pump to reduce the pump injection displacement from the first displacement to zero and keeping for a preset time period to settle the propping agent in the sand-carrying liquid; starting the pump again, pumping the sand-carrying liquid with the first volume into the wellhead, rapidly increasing the pumping displacement to the first displacement within 2min, and opening a new crack under the action of exciting pressure generated by the displacement reduction and displacement increase and pressure difference of 2-5 MPa generated by the sedimentation of the proppant in the crack to realize crack steering; repeating the process until the transformation of the casing change well section or the long section is completed; the first displacement is designed construction displacement or maximum construction displacement under the condition of wellhead pressure limiting. Specifically, aiming at the condition that a casing change well section or a long section exists in the shale fracturing process, the length of the casing change well section or the long section is more than 60m (even 1000 m), and the differential pressure of the casing change well section or the long section is 2-5 Mpa, the stratum which is reformed by using a multi-cluster perforation technology is needed. The number of possible opening perforation clusters is considered in advance, and the liquid amount and the sand amount of pumping are designed according to the number of the perforation clusters. After injecting the designed amount of sand-carrying liquid into the stratum, pumping slickwater to carry the sand-carrying liquid in the well boreThe sand fluid displaces into the formation. In order to guarantee the effect, the propping agent is settled at the seam of the artificial crack, and the slippery water is not suitable for being replaced excessively. And stopping the pump for a preset time period to reduce the construction displacement to 0. For example, the predetermined time period may be 10 to 40min, and further, the predetermined time period may be 20 to 30min. The concentration of the sand-carrying liquid can be 40-120 kg/m 3 Furthermore, the concentration of the sand carrying liquid can be 40-60 kg/m 3 . The number of the perforation clusters is more than 3, the first volume accounts for 1/N of the total liquid volume designed in the fracturing construction of the section, and N is the fracturing times of the section. Here, the number of fracturing is the number of pumping. When a long section is subjected to fracturing construction, the fracturing frequency is 2 times. When the casing deformation section is subjected to fracturing construction, the fracturing times are more than 2. The sand carrying fluid comprises a propping agent and a working fluid, and after the pump is stopped, the propping agent in the sand carrying fluid can generate an effect similar to a temporary plugging agent to plug the crack after being settled. And the pump is started again to pump the sand-carrying liquid into the stratum, so that the pump injection displacement is quickly increased to the maximum construction displacement under the designed construction displacement or wellhead pressure limiting condition, and the fracturing transformation is carried out. And repeating the process until the casing deformation well section or the long section is completely transformed. Here, the field may increase the number of fractures based on the microseismic monitoring results.
In summary, the beneficial effects of the invention can include at least one of the following:
(1) The problems of over-high torsional friction resistance and difficult sand adding can be effectively solved, and the conditions that the construction pressure is abnormal due to too little temporary plugging material added, the deformation is not in place, and the construction pressure is too high, the fracturing construction of the subsequent well section is difficult or the fracturing cannot be realized, and the fracturing can be continued only by adopting a blowout mode aiming at the casing deformation well section can be avoided;
(2) The fracturing construction method is convenient for field application, new complex conditions (construction time is prolonged due to overhigh pressure and overlow discharge capacity, sand blocking and blowout) cannot be caused to fracturing construction, the overall construction progress is influenced, and from the economic point of view, additional fracturing materials do not need to be added, and a bridge plug (a segmenting tool) does not need to be put into a set variable section or a long section (small stress difference), so that the fracturing transformation cost is reduced.
While the present invention has been described above in connection with exemplary embodiments, it will be apparent to those of ordinary skill in the art that various modifications may be made to the above-described embodiments without departing from the spirit and scope of the claims.
Claims (7)
1. A shale sand fracturing pump-stopping fracturing steering method is characterized in that the method aims at a stratum with pumping injection pressure rising close to wellhead pressure limiting and pumping injection displacement lower than 8m year transportation/min after a certain amount of sand-carrying liquid is pumped and injected into the stratum from 40 to 120kg/m in the shale fracturing process, and the fracturing steering method comprises the following steps:
pumping a sand-carrying liquid into a wellhead to polish a formation crack, and monitoring the change condition of pumping pressure in the pumping process;
under the condition that the pumping pressure rises at the slope change rate of more than 0 and reaches the wellhead pressure limiting, using slickwater to replace the sand-carrying fluid for pumping so as to replace the sand-carrying fluid in the shaft into the stratum;
after the replacement is finished, stopping the pump to reduce the pump injection displacement from the first displacement to zero and keeping for a preset time period to settle the propping agent in the sand-carrying liquid; the proppant in the sand-carrying fluid generates the effect of plugging the crack after being settled;
starting the pump again, keeping the liquid supply stable, pumping the preposed liquid into the wellhead and quickly increasing the pumping displacement to the first displacement within 2 min;
pumping and injecting the sand-carrying liquid again for fracturing construction after the preposed liquid is pumped and injected;
opening a new crack under the action of exciting pressure generated by the reduction and the increase of the discharge capacity and pressure difference of 2 to 5MPa generated by the sedimentation of the proppant in the crack, and realizing the crack steering;
repeating the above steps until the fracturing construction is completed;
the first displacement is designed construction displacement or maximum construction displacement under a wellhead pressure limiting condition; the proppant is a large-particle-size proppant, and the particle size of the large-particle-size proppant is 40-70 meshes.
2. A shale sand fracturing pump-stopping fracturing steering method is characterized in that the method aims at a stratum which cannot complete designed sand adding amount in the follow-up process and has a bottom hole pressure rising at a slope change rate of more than 0 after a certain amount of sand-carrying liquid is pumped into the stratum for 40-120kg/m and year, and the fracturing steering method comprises the following steps:
pumping a sand-carrying liquid into a wellhead to polish a formation crack, and monitoring the change condition of pumping pressure in the pumping process;
under the condition that the pumping pressure rises at the slope change rate of more than 0 and reaches the wellhead pressure limiting, using slickwater to replace the sand-carrying fluid for pumping so as to replace the sand-carrying fluid in the shaft into the stratum;
after the replacement is finished, stopping the pump to reduce the pump injection displacement from the first displacement to zero and keeping for a preset time period to settle the propping agent in the sand-carrying liquid; the proppant in the sand-carrying fluid generates the effect of plugging the crack after being settled;
starting the pump again, keeping the liquid supply to stably pump and inject the preposed liquid into the wellhead, quickly increasing the pump injection displacement to the first displacement within 2min, and opening a new crack under the action of excitation pressure generated by displacement reduction and displacement increase and pressure difference generated by proppant sedimentation in the crack and ranging from 2 to 5MPa to realize crack steering;
after the pre-liquid pumping is finished, adding silt to polish the newly opened crack and adding a propping agent to prop the crack;
repeating the above steps until the fracturing construction is completed;
the first displacement is designed construction displacement or maximum construction displacement under a wellhead pressure limiting condition; the proppant is a large-particle-size proppant, and the particle size of the large-particle-size proppant is 40-70 meshes.
3. The shale sand fracturing pump-stop fracturing diversion method according to claim 1 or 2, wherein the pumping amount of the pad liquid is 50 to 90m through year.
4. The shale sand fracturing pump-stop fracturing diverting method as claimed in claim 2, wherein the addition amount of the silt is 1 to 20t, the particle size of the silt is 70 to 140 meshes, and the particle size of the large-particle-size proppant is 40 to 70 meshes.
5. A shale sand fracturing pump-stopping fracturing steering method is characterized in that the method aims at a stratum with a casing change well section or a long section in the shale fracturing process, the length of the casing change well section or the long section is more than 60m, and the stress difference is 2-5 MPa, and the fracturing steering method comprises the following steps:
determining the pumping quantity of the sand-carrying fluid as a first volume according to the number of the first opened perforation clusters, and pumping the sand-carrying fluid with the first volume into the wellhead by using the first displacement to perform fracturing modification;
after the sand-carrying fluid is pumped, slickwater is used for replacing the sand-carrying fluid to pump and inject the residual sand-carrying fluid in the shaft into the stratum;
after the replacement is finished, stopping the pump to reduce the pump injection displacement from the first displacement to zero and keeping for a preset time period to settle the propping agent in the sand-carrying liquid; the proppant in the sand-carrying fluid generates the effect of plugging the crack after being settled;
the pump is started again, the sand-carrying liquid with the first volume is pumped into the wellhead, the pumping displacement is quickly increased to the first displacement within 2min, and a new crack is opened under the action of exciting pressure generated by the displacement reduction and displacement increase and pressure difference of 2-5 MPa generated by the sedimentation of the proppant in the crack, so that the crack steering is realized;
repeating the process until the transformation of the casing change well section or the long section is completed;
the first displacement is designed construction displacement or maximum construction displacement under a wellhead pressure limiting condition; the proppant is a large-particle-size proppant, and the particle size of the large-particle-size proppant is 40-70 meshes.
6. The shale sand fracturing pump-stop fracturing diverting method as claimed in claim 1, 2 or 5, wherein the predetermined time is 10 to 40min.
7. The shale sand fracturing pump-out fracturing diverting method as claimed in claim 5, wherein the number of the perforation clusters is more than 3 clusters, the first volume accounts for 1/N of the total liquid volume designed for the fracturing construction of the section, and N is the fracturing number of the section.
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