CN114059987B - Cluster type multistage clearance acidizing fracturing method and application thereof - Google Patents
Cluster type multistage clearance acidizing fracturing method and application thereof Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 41
- 239000002253 acid Substances 0.000 claims abstract description 90
- 238000002347 injection Methods 0.000 claims abstract description 14
- 239000007924 injection Substances 0.000 claims abstract description 14
- 238000005530 etching Methods 0.000 claims abstract description 8
- 239000012530 fluid Substances 0.000 claims description 68
- 238000006073 displacement reaction Methods 0.000 claims description 45
- 239000007788 liquid Substances 0.000 claims description 34
- 239000000243 solution Substances 0.000 claims description 20
- 230000001965 increasing effect Effects 0.000 claims description 9
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 5
- 230000000694 effects Effects 0.000 abstract description 15
- 239000003129 oil well Substances 0.000 abstract description 8
- 239000004215 Carbon black (E152) Substances 0.000 abstract description 6
- 229930195733 hydrocarbon Natural products 0.000 abstract description 6
- -1 carbonate hydrocarbon Chemical class 0.000 abstract description 4
- 238000013461 design Methods 0.000 abstract description 3
- 208000010392 Bone Fractures Diseases 0.000 description 40
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- 244000007835 Cyamopsis tetragonoloba Species 0.000 description 2
- DSLZVSRJTYRBFB-UHFFFAOYSA-N Galactaric acid Natural products OC(=O)C(O)C(O)C(O)C(O)C(O)=O DSLZVSRJTYRBFB-UHFFFAOYSA-N 0.000 description 2
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- 229920002907 Guar gum Polymers 0.000 description 1
- 235000019738 Limestone Nutrition 0.000 description 1
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Classifications
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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
Abstract
The invention discloses a cluster multistage gap acidizing and fracturing method and application thereof, wherein the method comprises the following steps: injecting into a joint at the first stage, and stopping the pump intermittently; injecting into a joint at the second stage, and intermittently stopping the pump; thirdly, injecting into a joint, and intermittently stopping the pump; fourth stage injection joint making; alternately injecting high-viscosity and low-viscosity acid liquor for etching; over-displacing. According to the method, after acid fracturing is completed, the fracture turns for a plurality of times, and the fracture-cavity body connected to the target azimuth and distance produces oil. The invention has reasonable design and obvious effect, can be widely used in single well fracturing of carbonate hydrocarbon reservoirs, and is particularly suitable for fracture-cavity type reservoirs. Thereby exerting the potential of the reservoir to the maximum extent and improving the effective period of the crack and the oil well yield.
Description
Technical Field
The invention belongs to the field of oil and gas field development, in particular relates to a yield increasing method in the field of oil and gas field development, and particularly relates to a clustered multistage gap acidizing fracturing method which is mainly applied to acid fracturing of carbonate rock oil and gas reservoirs.
Background
Fracturing and acidizing are abbreviated as acid fracturing. Acid liquor is used as fracturing fluid under the condition that the fracturing pressure is higher than the stratum fracture pressure, and fracturing without propping agent is carried out. In the acid pressing process, the wall surface of the crack is eroded into an uneven surface by the erosion action of the acid liquid, so that the wall surface of the crack can not be completely closed after the pump is stopped for pressure relief. Therefore, the water-based oil well has higher diversion capability and obvious effect on recovering and improving the production capability of the oil well. The method is suitable for carbonate reservoirs.
At present, the proportion of ultra-deep carbonate fracture-cavity type oil and gas reservoirs found is increasing. For example, in China petrochemical industry, the northbound hydrocarbon reservoir is commonly measured to have a sagging depth of 7000-9000m, and the hydrocarbon reservoir of the type is abnormal in fracture-cavity development, so that the lost fracture-cavity bodies are avoided during drilling, otherwise, the lost fracture-cavity loss can cause the great increase of the drilling period and even the normal drilling cannot be performed. Therefore, there is a strong demand for communicating the randomly distributed hole-shaped bodies by acid fracturing technology. However, if the acid fracturing cannot effectively communicate with the fracture-cavity body, the yield after acid fracturing is low and the decrease is rapid. However, the conventional acid fracturing technology has single crack formation and low probability of communicating the fracture-cavity body.
Aiming at the requirements, the fiber temporary plugging diversion acid fracturing technical research and the field test thereof in the past propose to adopt the fiber temporary plugging to realize diversion of acid etching cracks, thereby increasing the possibility of communicating the fracture-cavity bodies in different directions. However, the super-deep layer has large ground stress and narrow joint width, so that the temporary plugging agent is difficult to move into the cracks as expected by design. Therefore, even if a temporary plugging effect occurs, the diverted cracks are often in a position close to the shaft, the width of the joint is narrow, the induced stress is small, and the distance for inducing stress transmission is also small. Therefore, the difficulty is extremely high and even the completion is impossible to realize effective steering and fracturing to communicate the target fracture-cavity body at a certain direction and distance.
Meanwhile, considering that the distribution of the fracture-cavity body has great uncertainty, the single-well temporary plugging one-time acid fracturing technology is difficult to achieve the expected aim of communicating the fracture-cavity body, and a new technology needs to be researched and provided to solve the limitations.
Disclosure of Invention
In order to overcome the problems in the prior art and communicate more fracture-cavity bodies in different directions, the invention provides a clustered multistage intermittent acid fracturing technology, which maximally utilizes induced stress and interference effects thereof in the fracturing or acid fracturing process and realizes multiple fracture diversion. The method can exert the superposition effect of various stress interferences to the greatest extent, thereby increasing the probability of various steering joints to communicate the randomly distributed seam hole bodies with different sizes to the greatest extent, and not the effect of only communicating a single seam hole body in the past. Therefore, through the compound operation mode of cluster type multistage gap type fracturing and acid fracturing, the transformation effect and the effective period of a single well are greatly improved.
Therefore, the core mechanism of the invention is how to make the best use of the induced stress and the interference effect thereof in the fracturing or acid fracturing process. In particular, although the material is in an ultra-deep layer and has relatively high temperature and pressure, the lithology is mainly carbonate rock, and generally limestone is most (more than 90 percent is occupied), and the mineral content of other clay and the like is mostly less than 5 percent. The extremely high lithology of the brittle minerals is tested by experiments, and the brittle minerals still belong to the linear deformation category when the temperature is below 300 ℃. In other words, the induced stress, once formed, propagates relatively far away. According to the current research, the distance for inducing stress propagation is basically equivalent to the length of the seam. In addition, the magnitude of the induced stress is closely related to the net pressure within the fracture. Induced stress at 0m from the fracture face perpendicular to the fracture face is the net pressure within the fracture. Therefore, to increase induced stress in fracturing or acid fracturing, firstly, the volume of injected fracturing fluid and acid fluid is relatively high; secondly, injection displacement and viscosity of fracturing fluid and acid liquor are relatively high so as to obtain wider cracks; thirdly, temporary plugging in the seam is carried out, so that the net pressure in the seam is promoted to be rapidly increased.
One of the purposes of the invention is to provide a clustered multi-stage gap acidizing fracturing method, which comprises the following steps: the single-well multistage gap type fracturing operation and the multi-well cluster type simultaneous fracturing operation are combined.
In a preferred embodiment, the single well multi-stage gap fracturing operation comprises: multiple stages of intermittent fracturing operations (such as stopping the pump for a period of time between each stage of fracturing) are performed on a single well with multiple instantaneous pump stops and then pump starts.
In a further preferred embodiment, the pump is stopped between each stage of fracturing for 1 to 60 minutes, preferably 1 to 30 minutes, more preferably 1 to 20 minutes, for example 1 to 10 minutes.
In a further preferred embodiment, a non-reactive fracturing fluid, preferably at least one from among guar fracturing fluid, polymer fracturing fluid, carboxymethyl hydroxypropyl guar fracturing fluid and slickwater, is used in performing the multistage gap fracturing operation.
Considering that the ultra-deep hydrocarbon reservoir is extremely limited in induced stress formed by primary fracturing or acid fracturing, even if a temporary plugging method in a seam is adopted, the temporary plugging range is mostly in a near-wellbore fracture zone, the steering radius is very small, and the aim of the fracture-cavity body which can be communicated only by the expected larger steering angle and steering radius is difficult to realize.
Therefore, in single well fracturing or acid fracturing, multi-stage gap (intermittent) operation modes such as multiple instantaneous pump stoppage and pump restarting are adopted, and the non-reactive fracturing fluid is adopted to perform multi-stage gap type operation, so that the induced stress generated in the fracturing process is larger than that of acid fracturing (because acid rock reaction consumes a part of rock, the width of a crack is larger, but the net pressure in the crack is possibly reduced instead). And the size of each fracture is relatively large.
In a preferred embodiment, the viscosity of the fracturing fluid increases stepwise as each stage of fracturing operation proceeds.
In a further preferred embodiment, the displacement of the fracturing fluid is optionally increased stepwise as each stage of fracturing operation proceeds, preferably in units of each stage.
In order to save the cost of the fracturing fluid, and also in order to ensure that new cracks can be extended on new crack initiation angles after each gap type fracturing, the viscosity and the discharge capacity of the fracturing fluid after each pumping are gradually improved. Therefore, the highest viscosity and displacement of the fracturing fluid are required to be determined through simulation in advance, and then the combination of the viscosity and displacement of the fracturing fluid in the earlier stage is determined according to the number of stages of the gap.
Therefore, after the multi-stage gap type operation mode is adopted, as long as the crack length of each stage of fracturing is large enough, the propagation distance of induced stress is close to the crack length direction, so that the superposition effect of induced stress formed by each stage of cracks is larger and larger, and finally, the turning radius of the turning crack is also greatly improved (the larger the stress turning area formed by the induced stress is, the larger the turning radius is, once the stress turning area is broken through, the turned crack is turned to the direction of the original maximum horizontal main stress again).
In the invention, the stress field is continuously changed by adopting multiple gap injection, so that the gradual steering of the crack is realized. Thus, the cracks gradually deviate from the original principal force stress direction, and target reservoirs with certain directions and distances are effectively communicated.
In a preferred embodiment, in single well fracturing, low-viscosity high-displacement fracturing fluid is injected after the multi-stage gap fracturing operation to perform cooling and expanding operations.
In a further preferred embodiment, the high viscosity acid solution and the low viscosity acid solution are alternately injected for etching after the expanding operation.
In a preferred embodiment, the multi-well clustered simultaneous fracturing operation comprises: within a well group or groups, each of the operating steps for all of the wells is performed simultaneously, including simultaneously starting up the pump, simultaneously stopping the pump, and simultaneously exchanging the fracturing fluid or acid.
In other words, the multi-well cluster mode of action is multi-well synchronous replication of single-well multi-stage gap type operation. The method aims at utilizing the induced stress superposition effect caused by single-well multistage gap type operation and temporary plugging in the seam, carrying out the same induced stress interference effect on a plurality of adjacent wells, and finally exerting the superposition effect of various stress interferences to the greatest extent in a well group or a hydrocarbon reservoir unit covered by a plurality of well groups, thereby maximally increasing the probability of various steering seams for communicating the seam hole bodies with different sizes of random distribution, and not the prior assumption for communicating only a single seam hole body. Therefore, through the compound operation mode of cluster type multistage gap type fracturing and acid fracturing, the transformation effect and the effective period of a single well are greatly improved.
In a preferred embodiment, the clustered multi-stage gap acidizing fracturing method comprises the steps of:
(1) Injecting low-viscosity medium-displacement fracturing fluid to perform first-stage seam making, and intermittently stopping the pump;
(2) Injecting medium-viscosity medium-displacement fracturing fluid to perform secondary seam making, and intermittently stopping the pump;
(3) Injecting high-viscosity high-displacement fracturing fluid to perform third-stage joint making, and intermittently stopping the pump;
(4) Injecting high-viscosity high-displacement acid liquor to finish the last stage of seam making;
(5) Injecting a low-viscosity high-displacement fracturing fluid to perform cooling and seam expanding operation;
(6) Injecting high-viscosity high-discharge acid liquor to perform high-viscosity acid injection operation;
(7) Injecting low-viscosity high-discharge acid liquor to perform high-viscosity acid injection operation;
(8) Repeating the steps (6) to (7);
(9) Displacing operation;
(10) If one well group or a plurality of well groups exist, adopting a cluster type simultaneous operation mode, and repeating the steps (1) to (9) until all the wells are constructed.
Wherein the non-reactive common fracturing fluid adopted in the step (1) to the step (4) is at least one selected from guar gum fracturing fluid, polymer fracturing fluid, carboxymethyl hydroxypropyl guar gum fracturing fluid and slickwater. The acid liquid adopted in the step (5) to the step (8) is at least one selected from gelled acid, ground crosslinking acid, variable viscosity acid and turning acid.
In a preferred embodiment, in the step (1), the first-stage fracture length is 40% -80%, preferably 60% of the projection length of the connecting line of the well bore and the fracture cavity in the original maximum principal stress direction.
In a preferred embodiment, in step (1), the fracturing fluid displacement is from 2 to 3m 3 The viscosity of the fracturing fluid is 2-3mPa.s, and the liquid amount of the fracturing fluid is 150-200m 3 。
In the step (1), commercial optimization design software such as STIMPLAN, frac ProPT and the like for fracturing or acid fracturing is applied to simulate the three-dimensional geometric dimensions and the flow conductivity of cracks under different liquid properties (fracturing fluid and acid fluid), liquid volume, displacement and viscosity. And determining the fracturing or acid fracturing construction parameters under the target fracture length, and carrying out fracturing construction according to the parameters.
After the construction of step (1), the pump is stopped instantaneously for 1 to 60 minutes, preferably 1 to 30 minutes, more preferably 1 to 20 minutes, for example 1 to 10 minutes.
In a preferred embodiment, in step (2), the fracturing fluid displacement is from 2 to 3m 3 The viscosity of the fracturing fluid is 15-20mPa.s, and the liquid amount of the fracturing fluid is 130-150m 3 。
In a preferred embodiment, in the step (2), the second stage fracture length is 10% -50%, preferably 20% of the projected length of the connecting line of the well bore and the fracture cavity in the original maximum principal stress direction.
In the step (2), commercial optimization design software such as STIMPLAN, frac ProPT and the like for fracturing or acid fracturing is applied to simulate the three-dimensional geometric dimensions and the flow conductivity of the fracture under different liquid properties (fracturing fluid and acid fluid), liquid volume, displacement and viscosity.
After the construction of step (2), the pump is stopped instantaneously for 1 to 60 minutes, preferably 1 to 30 minutes, more preferably 1 to 20 minutes, for example 1 to 10 minutes.
In a preferred embodiment, in step (3), the fracturing fluid displacement is in the range of 5 to 6m 3 The viscosity of the fracturing fluid is 50-60mPa.s, and the liquid volume of the fracturing fluid is 100-120m 3 。
In a preferred embodiment, in the step (3), the third stage fracture length is 10% -40%, preferably 20% of the projected length of the connecting line of the well bore and the fracture cavity in the original maximum principal stress direction.
In the step (3), commercial optimization design software such as STIMPLAN, frac ProPT and the like for fracturing or acid fracturing is applied to simulate the three-dimensional geometric dimensions and the flow conductivity of the fracture under different liquid properties (fracturing fluid and acid fluid), liquid volume, displacement and viscosity.
After the construction of step (3), the pump is stopped instantaneously for 1 to 60 minutes, preferably 1 to 30 minutes, more preferably 1 to 20 minutes, for example 1 to 10 minutes.
In a preferred embodiment, in step (4), the acid liquor displacement is from 5 to 6m 3 The viscosity of the acid solution is 70-80mPa.s per minute, and the liquid amount of the acid solution is 40-50m 3 。
In a preferred embodiment, in step (4), the fourth stage fracture length is equal to 10% to 30%, preferably 20%, of the length of the connection between the wellbore and the fracture body.
In the step (4), commercial optimization design software such as STIMPLAN, frac ProPT and the like for fracturing or acid fracturing is applied to simulate the three-dimensional geometric dimensions and the flow conductivity of the fracture under different liquid properties (fracturing fluid and acid fluid), liquid volume, displacement and viscosity. From which the fracturing or acid fracturing parameters at the target fracture length are determined.
In a preferred embodiment, in step (5), the fracturing fluid displacement is from 5 to 6m 3 The viscosity of the fracturing fluid is 1-10mPa.s, and the liquid amount of the fracturing fluid is 200-800m 3 。
In a preferred embodiment, in step (6), the acid liquor displacement is from 5 to 6m 3 The viscosity of the acid solution is 40-100mPa.s per min, and the liquid amount of the acid solution is 100-400m 3 。
In a preferred embodiment, in step (7), the acid liquor displacement is from 5 to 6m 3 Per min, the viscosity of the acid solution is 4-10mPa.s, and the liquid amount of the acid solution is 100-300m 3 。
And (3) the step (6) and the step (7) realize viscosity fingering, which is beneficial to etching effect.
In a preferred embodiment, in step (9), the displacement is performed at 110-300% of the wellbore volume.
In a further preferred embodiment, in step (9), the displacement is carried out with low viscosity slickwater of 2-3 mpa.s.
According to the method, after acid fracturing is completed, the fracture turns for a plurality of times, and the fracture-cavity body connected to the target azimuth and distance produces oil.
The second purpose of the invention is to provide an application of the clustered multi-stage intermittent acidizing fracturing method in acid fracturing of carbonate rock oil and gas reservoirs.
The method is mainly applied to acid fracturing of carbonate rock oil and gas reservoirs, and has wide application prospects in the fields of a tower river, a northbound oil and gas field and a Tarim oil and gas field.
The endpoints of the ranges and any values disclosed in the present invention are not limited to the precise range or value, and the range or value should be understood to include values close to the range or value. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein. In the following, the individual technical solutions can in principle be combined with one another to give new technical solutions, which should also be regarded as specifically disclosed herein.
Compared with the prior art, the invention has the following beneficial effects: the invention has reasonable design and obvious effect, can be widely used in single well fracturing of carbonate hydrocarbon reservoirs, and is particularly suitable for fracture-cavity type reservoirs. Thereby exerting the potential of the reservoir to the maximum extent and improving the effective period of the crack and the oil well yield.
Drawings
FIG. 1 is a schematic diagram showing the principle of the fracturing method of the invention for communicating with a fracture-cavity body;
1-a wellbore; 2-a hole sewing body; 3-the direction of maximum principal stress; 4-turning crack.
Detailed Description
The present invention is described in detail below with reference to specific embodiments, and it should be noted that the following embodiments are only for further description of the present invention and should not be construed as limiting the scope of the present invention, and some insubstantial modifications and adjustments of the present invention by those skilled in the art from the present disclosure are still within the scope of the present invention.
In addition, the specific features described in the following embodiments may be combined in any suitable manner without contradiction. The various possible combinations of the invention are not described in detail in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention can be made, so long as the concept of the present invention is not deviated, and the technical solution formed thereby is a part of the original disclosure of the present specification, and also falls within the protection scope of the present invention.
The raw materials used in examples and comparative examples, if not particularly limited, are all as disclosed in the prior art, and are, for example, available directly or prepared according to the preparation methods disclosed in the prior art.
[ example 1 ]
A well depth of 5548 meters, a target fracture-cavity body containing oil is 102 meters away from the well bore, and the maximum main stress direction angle is 35 degrees. Three-stage intermittent acid pressing is adopted.
The first stage injection displacement is 2.5m 3 The viscosity is 3mPa.s and the liquid volume is 150m 3 . After the construction at this stage is completed, the pump is stopped instantaneously for 2min.
The second-stage injection displacement is 3m 3 The viscosity is 15mPa.s, and the liquid volume is 130m 3 . After the construction at this stage is completed, the pump is stopped instantaneously for 4min.
The third-stage injection displacement is 5m 3 The viscosity is 50mPa.s, and the liquid volume is 120m 3 . After the construction at this stage is completed, the pump is stopped instantaneously for 1min.
Fourth stage injection displacement is 6m 3 The viscosity is 75mPa.s, and the liquid volume is 40m 3 。
After intermittent construction, the displacement is injected again for 6m 3 Fracturing fluid with viscosity of 2-3mPa.s per min of 350m 3 And cooling and expanding the seam.
Displacement of 6m 3 High viscosity crosslinking acid 150m with viscosity of 50mPa.s per min 3 +displacement 6m 3 Low-viscosity mucic acid 100m with viscosity of 5 Pa.s per min 3 And performing viscosity finger etching.
Displacement of 6m 3 High viscosity crosslinking acid 150m with viscosity of 50mPa.s per min 3 +displacement 6m 3 Low-viscosity mucic acid 100m with viscosity of 5 Pa.s per min 3 And performing viscosity finger etching.
Slick water 100m 3 And (3) displacing.
After the well is closed for 60 minutes, the well is opened for open flow and production. In the oil extraction process, the initial yield of the oil well is 147 tons/day, and after one year of production, the daily yield is still kept at 102 tons/day and the wellhead pressure is 18 megapascals. The yield pressure is always kept at a higher level, and the acid fracturing cracks effectively trench-open the fracture-cavity body. It can be seen that the yield of the oil well constructed by acid fracturing by the method is remarkably improved.
[ example 2 ]
Some well depth 7980 meters, the target fracture-cavity body containing oil is 85 meters away from the shaft, and the maximum main stress direction angle is 22 degrees. Two stages of inter-stage acid pressing are employed.
The first-stage injection displacement is 4m 3 The viscosity is 3mPa.s, and the liquid volume is 200m 3 . After the construction at this stage is completed, the pump is stopped instantaneously for 5min.
The second-stage injection displacement is 5m 3 The viscosity is 20mPa.s, and the liquid volume is 120m 3 . After the construction at this stage is completed, the pump is stopped instantaneously for 5min.
The third-stage injection displacement is 6m 3 The viscosity is 50mPa.s, and the liquid volume is 120m 3 . After the construction at this stage is completed, the pump is stopped instantaneously for 3min.
After intermittent construction, the water is injected into the water with the discharge capacity of 8m 3 500m slickwater with viscosity of 2-3mPa.s per min 3 And cooling and expanding the seam.
Displacement of 7m 3 High viscosity crosslinking acid 200m with viscosity of 50mPa.s per min 3 +displacement 9m 3 Cross-linked acid-based liquid 120m with viscosity of 10mPa.s per min 3 And performing viscosity finger etching.
Slick water 200m 3 And (3) displacing.
After the well is closed for 60 minutes, the well is opened for open flow and production. During oil recovery, the initial production of the oil well is 208 tons/day, and the wellhead pressure is 35 megapascals. The yield pressure is always kept at a higher level, and the acid fracturing cracks effectively trench-open the fracture-cavity body. It can be seen that the yield of the oil well constructed by acid fracturing by the method is remarkably improved.
The invention has been described in detail in connection with the specific embodiments and exemplary examples thereof, but such description is not to be construed as limiting the invention. It will be understood by those skilled in the art that various equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its embodiments without departing from the spirit and scope of the present invention, and these fall within the scope of the present invention. The scope of the invention is defined by the appended claims.
Claims (15)
1. A clustered multi-stage gap acidizing fracturing method comprising: adopting the combination of single-well multistage gap type fracturing operation and multi-well cluster type simultaneous fracturing operation; the single well multistage gap fracturing operation comprises: performing multi-stage gap type fracturing operation of stopping and restarting the pump for a single well for a plurality of times; the multi-well clustered simultaneous fracturing operation comprises: within a well group or a plurality of well groups, each operation step of all wells is synchronously carried out, including simultaneously starting up the pump, simultaneously stopping the pump, simultaneously changing the fracturing fluid or the acid fluid;
the clustered multistage clearance acidizing fracturing method comprises the following steps of: (1) Injecting low-viscosity medium-displacement fracturing fluid to perform first-stage seam making, and intermittently stopping the pump; (2) Injecting medium-viscosity medium-displacement fracturing fluid to perform secondary seam making, and intermittently stopping the pump; (3) Injecting high-viscosity high-displacement fracturing fluid to perform third-stage joint making, and intermittently stopping the pump; (4) Injecting high-viscosity high-displacement acid liquor to finish the last stage of seam making; (5) Injecting a low-viscosity high-displacement fracturing fluid to perform cooling and seam expanding operation; (6) Injecting high-viscosity high-discharge acid liquor to perform high-viscosity acid injection operation; (7) Injecting low-viscosity high-discharge acid liquor to perform low-viscosity acid injection operation; (8) repeating the steps (6) - (7); (9) displacing operation; (10) If one well group or a plurality of well groups exist, adopting a cluster type simultaneous operation mode, and repeating the steps (1) - (9) until all the wells are constructed.
2. The fracturing method of claim 1, wherein pumps are stopped for 1-60min between each stage of fracturing in the single well multi-stage gap fracturing operation.
3. The fracturing method of claim 2, wherein pumps are stopped for 1-30 min between each stage of fracturing.
4. A fracturing method according to claim 1, characterized in that,
as the fracturing operation of each stage is carried out, the viscosity of the fracturing fluid is gradually increased; and/or
As each stage of fracturing operation proceeds, the displacement of fracturing fluid increases step by step.
5. The fracturing method of claim 4, wherein the displacement of fracturing fluid is increased in units of each two stages.
6. The fracturing method of claim 1, wherein in single well fracturing, a low viscosity high displacement fracturing fluid is injected after the multi-stage gap fracturing operation for a cool down and expansion operation.
7. The fracturing method of claim 6, wherein high viscosity acid solution and low viscosity acid solution are alternately injected for etching after the expanding operation.
8. The fracturing method of claim 1, wherein in step (1):
the length of the first-stage crack is 40% -80% of the projection length of a connecting line of the shaft and the crack hole body in the original maximum main stress direction; and/or
The discharge capacity of the fracturing fluid is 2-3m 3 The viscosity of the fracturing fluid is 2-3mPa.s, and the liquid amount of the fracturing fluid is 150-200m 3 。
9. The fracturing method of claim 1, wherein in step (2):
the length of the second-stage crack is 10% -50% of the projection length of the connecting line of the shaft and the crack hole body in the original maximum main stress direction; and/or
The discharge capacity of the fracturing fluid is 2-3m 3 The viscosity of the fracturing fluid is 15-20mPa.s, and the liquid amount of the fracturing fluid is 130-150m 3 。
10. The fracturing method of claim 1, wherein in step (3):
the third-stage crack length is 10% -40% of the projection length of the connecting line of the shaft and the crack hole body in the original maximum main stress direction; and/or
The discharge capacity of the fracturing fluid is 5-6m 3 The viscosity of the fracturing fluid is 50-60mPa.s, and the liquid volume of the fracturing fluid is 100-120m 3 。
11. The fracturing method of claim 1, wherein in step (4):
the length of the fourth-stage crack is 10% -30% of the length of a connecting line of the shaft and the fracture-cavity body; and/or
The acid liquor discharge capacity is 5-6m 3 The viscosity of the acid solution is 70-80mPa.s per minute, and the liquid amount of the acid solution is 40-50m 3 。
12. A fracturing method according to claim 1, characterized in that,
in the step (5), the fracturing fluid discharge capacity is 5-6m 3 The viscosity of the fracturing fluid is 1-10mPa.s, and the liquid amount of the fracturing fluid is 200-800m 3 The method comprises the steps of carrying out a first treatment on the surface of the And/or
In the step (6), the acid liquid discharge amount is 5-6m 3 The viscosity of the acid solution is 40-100mPa.s per min, and the liquid amount of the acid solution is 100-400m 3 The method comprises the steps of carrying out a first treatment on the surface of the And/or
In the step (7), the acid liquid discharge amount is 5-6m 3 Per min, the viscosity of the acid solution is 4-10mPa.s, and the liquid amount of the acid solution is 100-300m 3 。
13. The fracturing method of claim 1, wherein in step (9), the displacing is performed at 110-300% of the wellbore volume.
14. The fracturing method of claim 13, wherein the displacing is performed with low viscosity slickwater of 2-3 mpa.s.
15. Use of the clustered multi-stage interstitial-acid fracturing method according to one of claims 1 to 14 in acid fracturing of carbonate reservoirs.
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