CN112443303A - Method for controlling crack propagation direction - Google Patents
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- CN112443303A CN112443303A CN201910830208.9A CN201910830208A CN112443303A CN 112443303 A CN112443303 A CN 112443303A CN 201910830208 A CN201910830208 A CN 201910830208A CN 112443303 A CN112443303 A CN 112443303A
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- 238000000034 method Methods 0.000 title claims abstract description 39
- 238000010276 construction Methods 0.000 claims abstract description 74
- 239000002253 acid Substances 0.000 claims abstract description 68
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 17
- 239000007788 liquid Substances 0.000 claims description 64
- 238000002347 injection Methods 0.000 claims description 58
- 239000007924 injection Substances 0.000 claims description 58
- 239000012530 fluid Substances 0.000 claims description 53
- 238000006073 displacement reaction Methods 0.000 claims description 32
- 239000004576 sand Substances 0.000 claims description 12
- 239000000243 solution Substances 0.000 claims description 12
- 239000003292 glue Substances 0.000 claims description 11
- 238000005457 optimization Methods 0.000 claims description 8
- 238000011156 evaluation Methods 0.000 claims description 7
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 6
- 238000012986 modification Methods 0.000 abstract description 2
- 230000004048 modification Effects 0.000 abstract description 2
- 206010017076 Fracture Diseases 0.000 description 61
- 208000010392 Bone Fractures Diseases 0.000 description 53
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- 238000005553 drilling Methods 0.000 description 4
- 238000005755 formation reaction Methods 0.000 description 4
- 239000011435 rock Substances 0.000 description 4
- 238000011161 development Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 208000006670 Multiple fractures Diseases 0.000 description 2
- 239000003245 coal Substances 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 239000007943 implant Substances 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 239000011148 porous material Substances 0.000 description 2
- 238000005086 pumping Methods 0.000 description 2
- 238000005507 spraying Methods 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 238000009933 burial Methods 0.000 description 1
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- 230000002349 favourable effect Effects 0.000 description 1
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- 239000010419 fine particle Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
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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
- E21B43/25—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 discloses a method for controlling crack propagation direction. The method comprises the following steps: (1) evaluating and optimizing parameters; (2) performing shower hole operation; (3) acid pretreatment operation; (4) constructing a main crack; (5) stopping the pump; (6) performing fracturing construction on a second and subsequent main cracks, and repeating the steps (4) to (5); (7) injecting 70-140 meshes of propping agent for construction; (8) injecting 40-70 mesh proppant for construction; (9) injecting 30-50 meshes of propping agent for construction; (10) and (5) replacing operation. The invention reduces the horizontal main stress difference by utilizing the induced stress brought by forming the artificial crack each time, thereby improving the length of the next artificial crack extending along the direction of the non-maximum main stress, communicating reservoirs in other directions and improving the oil gas productivity. After 2-3 times of fracturing of different scales, the modification range of the artificial fracture in the transverse direction is improved by 4-6 times compared with the conventional fracturing mode.
Description
Technical Field
The invention relates to the technical field of petroleum drilling, in particular to a method for controlling the crack propagation direction.
Background
At present, the fracture direction of hydraulic fracturing is generally perpendicular to the direction of minimum horizontal principal stress. Such as horizontal fractures, generally occur with minimal overburden stress, and occur in relatively small proportions in mines, most often in shallow layers with burial depths of less than 700 m. Thus, the present application primarily discusses vertical fractures.
Since the minimum horizontal stress direction of the reservoir is fixed in the initial state, the fracture direction in hydraulic fracturing is relatively fixed and cannot be changed artificially. And the direction of the fracture is often required to be changed on site, if the direction is changed, the hydraulic fracture can communicate with a reservoir body with better oil and gas properties, and the single well yield can be greatly improved after fracturing.
Chinese patent CN1303309C discloses a method for controlling the propagation direction of injection fractures in permeable formations. It is the control fracture that forms a path that extends in a vertical plane to a wider extent along the injection well and in net coincidence with the injection, and there is no reference to how to control the fracture extension in other directions by means of multiple fractures
Chinese patent CN105239984A discloses a coal mine underground fracturing crack propagation control method. The purpose is that its pressurize water injection is carried out through the direction drilling to predetermineeing in the coal seam, can form a continuous banding high pore pressure region around the fracturing drilling, and the induced hydraulic pressure crack is along the regional extension of high pore pressure, increases effective fracturing scope, does not relate to how to control the crack through the mode of fracturing many times and extend in other directions.
Chinese patent CN105842067A discloses a device and method for testing stress variation and crack propagation direction. The device and the method for testing the stress change and the crack propagation direction in the core fracturing process can test the stress change and the crack propagation direction, and how to control the crack to extend in other directions in a multi-fracturing mode is not involved.
Chinese patent CN107203667A discloses a multi-cluster fracturing optimization method and system in a horizontal well section, which are applied to a multi-cluster fracturing optimization device in the horizontal well section, wherein a fracturing fluid flow control equation set, a stress interference calculation control equation set and a multi-fracture synchronous expansion three-dimensional form calculation equation set are established according to formation parameters and multiple sets of construction parameters by the multi-cluster fracturing optimization method in the horizontal well section, and on the basis, a multi-cluster fracture three-dimensional extension model in the horizontal well section is established by considering inter-fracture stress and flow dynamic distribution, and how to control the extension of the fracture in other directions in a multi-fracture mode is not involved.
Therefore, there is currently no targeted measure on how to achieve a change in fracture direction by fracturing. Therefore, it is necessary to develop a new fracturing technology capable of changing the direction of the fracture to solve the above limitations.
Disclosure of Invention
In order to solve the problems in the prior art, the invention provides a method for controlling the crack propagation direction. On the basis of conventional reservoir parameter evaluation, firstly, acid pretreatment operation is adopted, then, a small-scale main fracture is constructed, then a pump is stopped, and then fracturing construction of a second main fracture and subsequent main fractures is started. And finally, 70-140 meshes of propping agent and 40-70 meshes of propping agent are injected into the main fracture at a low sand ratio, so that the sand ratio is improved, and the propping effect of each fracture is improved by injecting 30-50 meshes of propping agent. The purpose is to utilize the induced stress that each time forms artificial crack and bring, reduce horizontal principal stress difference to improve the length that next artificial crack extends along non-biggest principal stress direction, thereby reach the purpose of communicating other position reservoir bodies.
The invention aims to provide a method for controlling the crack propagation direction.
The method comprises the following steps:
step (1) parameter evaluation and optimization;
step (2), performing shower hole operation;
step (3) acid pretreatment operation;
constructing a main crack for forming a seam;
step (5), stopping the pump;
step (6) performing fracturing construction on the second and subsequent main cracks, and repeating the steps (4) to (5);
step (7), injecting 70-140 meshes of propping agent for construction;
step (8), injecting 40-70 mesh proppant for construction;
step (9) injecting 30-50 mesh proppant for construction;
and (10) replacing operation.
Among them, preferred are:
the step (1) comprises the following steps: evaluating key reservoir parameters, comprehensively judging and selecting the positions of the section clusters, optimizing fracture parameters and optimizing fracturing construction parameters.
In the step (2), the perforation length is 1-5m, the hole density is 8-20 holes/m, and the hole diameter is 5-20mm
In the step (3), the discharge capacity of the acid injection is 1-1.5m3Min, acid dosage is 10-20m3；
When the first cluster of perforation positions close to the heel part is not reached after all the acid injection is finished; injecting 9-15mPa.s of fracturing fluid to replace acid, and increasing the displacement of the acid to 4-6m3Min; after the acid begins to enter the first cluster of perforation positions close to the heel, the displacement of the acid is reduced to the previous displacement of the acid injection again;
after 20-30% of acid enters the first perforation cluster close to the heel, the discharge capacity of the acid is increased step by step 1-2 times, and the discharge capacity increased each time is 0.5-2m3Between/min, e.g. 6-7m3Min and 8-9m3And/min, the displacement is extracted in several times, and the displacement of acid corresponds to the average distribution.
In the step (4), construction is carried out according to the optimized construction parameters of the first main crack, low-viscosity fracturing fluid with the viscosity of 9-15mPa.s is injected, and the fluid volume is 50-60m3The discharge capacity is 3-4m3Min; and after 30-40% of the fracturing fluid is injected, 230-325-mesh fine proppant is added, and the sand-fluid ratio is 2-4-6% in a continuous injection mode.
The liquid amount of each section of sand-liquid ratio can be distributed according to the rest fracturing liquid amount, and can be equally divided, the low sand-liquid ratio can be less, and the high sand-liquid ratio is properly higher. However, if the pressure at the wellhead changes to over 1MPa within 1min, the sand-liquid ratio should be properly reduced.
In the step (5), after the construction in the step 4) is finished, the pump is immediately stopped for 1-2 min.
In the step (6), in the subsequent crack construction, the discharge capacity is gradually increased by 20-30%, the fracturing fluid amount is gradually increased by 30-40%, and the viscosity of the fracturing fluid is gradually increased by 10-20%; the pump stopping time is increased by 50-60% step by step. The sand-liquid ratio is gradually explored and increased, the sand-liquid ratio is determined by optimizing fracturing construction parameters, and specifically, the influence of different fracturing liquid viscosities on the length of a fracture under different liquid amounts is calculated.
The fracturing fluid is conventional in the field, such as slickwater, glue solution and the like, as long as the viscosity is within the range.
In the step (7), slickwater with the viscosity of 2-3mPa.s and 70-140 meshes of propping agent are adopted for injection construction, and the liquid amount accounts for 50-60% of the total amount of the sand-carrying liquid; the sand-liquid ratio is 2-4-6-8-10-12-14%.
In the step (8), slickwater with the viscosity of 6-9mPa.s and 40-70 meshes of propping agent are adopted for injection construction, and the liquid amount accounts for 20-30% of the total amount of the sand carrying liquid; a long slug mode or a continuous sand adding mode, and the sand-liquid ratio is 6-8-10-12-14%.
In the step (9), slickwater with the viscosity of 50-60mPa.s and 30-50 meshes of propping agent are adopted for injection construction, and the liquid amount accounts for 10-20% of the total amount of the sand-carrying liquid; a continuous injection mode, wherein the sand-liquid ratio is 16-19-22-25-28%;
and (10) designing displacement liquid amount according to 110% of 105-plus of the volume of the current section of the well bore, wherein the first 30-40% of liquid amount is high-viscosity glue solution with the viscosity of 50-60mPa.s, and then replacing low-viscosity slick water with the viscosity of 2-3mPa.s for injection until the displacement injection is completed.
The technical idea of the invention is as follows:
1) the induced stress effect of the fractured crack is utilized to realize the reversal of the stress direction near the crack.
In the fracturing process, along with the expansion of the crack, the net pressure in the crack is larger and larger, the induced stress in the direction vertical to the crack is larger and larger, and the propagation distance is further and further. There is also induced stress in the direction of the fracture, but it is relatively small and has little effect on the fracture steering and is not considered by the present invention. Only the stress inversion zone may be able to induce a reversal of the crack. The area of the stress inversion region needs to be properly controlled, otherwise, the angle of the second main crack extending again may be different from that of the first main crack, which is not favorable for the precise control of the crack direction. On the contrary, if the range of the induced stress inversion region is relatively small, the deflection angle of the second main crack with respect to the first main crack is relatively small, and if the stress inversion is induced for many times, the deflection angle of the second main crack can be controlled more accurately. Therefore, the final main crack can extend to the expected direction through repeatedly sewing.
In addition, although the induced stress action region outside the stress inversion region cannot generate direct steering effect in the subsequent main crack extension, the induced stress of the non-inversion region of all cracks has a superposition effect, so that the steering of the late main crack is facilitated.
2) Multiple main cracks required in the realization idea 1): different primary fracture extensions may be achieved by multiple fractures. I.e. after the first main crack has formed, the pump is momentarily stopped. Then measures such as high-viscosity fracturing fluid, quick pumping capacity and the like are used to ensure that the second main crack extends along a direction different from the first main crack. Otherwise, the low viscosity fracturing fluid, combined with the low displacement, may extend along the first primary fracture even if the stress is reversed. And after the pump is stopped for a plurality of times later, adopting the fracturing fluid with higher and higher viscosity.
In order to reduce the fracturing fluid amount of the multiple main fractures, the fracturing fluid amount of the first main fracture is minimum, the discharge capacity is also minimum, the fracturing fluid amount and the discharge capacity are gradually increased in the later main fracture construction until the last main fracture reaches the predicted steering effect, the fracturing fluid amount is increased and the highest injection discharge capacity is used, so that the requirements of the expected fracture length, height and width of the fracturing design are met. In order to further reduce the filtration loss of the main cracks, improve the crack formation efficiency and facilitate effective support at the tips of the cracks, a proppant with a fine particle size of 230-325 meshes can be added in the crack formation construction of the main cracks.
Although only the section with the best physical property or the lowest stress in the target layer is pressed open preferentially in the process of turning the subsequent main fracture, the section without the pressed open can still extend along the initial maximum horizontal main stress direction in the fracturing construction of the subsequent main fracture due to the lack of the rising induced stress and the superposition effect thereof, but the occurrence probability of the situation is relatively small. In the subsequent main fracture construction and fracture construction, the proportion of the intervals pressed open in the target layer is larger and larger along with the gradual increase of the fracturing fluid amount and the displacement. Therefore, when the last main crack extends, the net pressure in the crack is the largest, and the last main crack is easily pressed open up and down along the direction of the crack which turns first through the high inertia effect.
The specific measures of the invention are as follows:
(1) evaluation of key reservoir parameters: the evaluation of physical property, rock mechanical parameters, three-dimensional ground stress, natural crack development and the like can be carried out by means of earthquake, well logging, adjacent well testing, pilot hole well core indoor testing and the like.
(2) The method can be realized by means of earthquake, well logging, adjacent well testing, pilot hole well core indoor testing and the like: on the basis of the step 1), a conventional geological dessert and engineering dessert calculation method is applied, and a continuous distribution profile of the final geological engineering comprehensive dessert along the horizontal well section is determined according to an equal weight method. And then, comprehensively judging and selecting the cluster position of the section according to 2-3 clusters in the section and the comprehensive dessert difference between the clusters in the section is less than 20% by combining the cluster spacing optimized in the step 3) and the well cementation quality of the horizontal shaft.
(3) The crack parameters are preferably as follows: establishing a fine geological model of a target well layer on the basis of the step 1), then introducing geological parameters into general commercial simulation software ECLIPSE for fracturing well yield prediction, setting hydraulic fractures according to an equivalent flow conductivity method, and simulating different fracture parameters including fracture length, flow conductivity, fracture spacing and fracture layout according to an orthogonal design method, wherein the yield is relatively highest after the pressure is optimized from the middle, or a fracture parameter system corresponding to the highest net present value is the optimal value by taking the economic net present value after the pressure as a target function.
On the basis, if a certain position is known to have high oil and gas enrichment, the distance between the certain position and the position of the shower hole can be used as the optimal fracture length, but other fracture parameters are not changed. And the included angle between the connecting line direction of the oil gas enrichment body and the shower hole and the original maximum main stress direction is the final main crack deflection angle. If the deflection angle is divided by 10, and the result is rounded, the required number of main cracks is determined.
(4) Optimizing fracturing construction parameters: in order to obtain the fracture parameter system optimized in the step 3), common commercial software for fracturing fracture expansion simulation is used for simulating the dynamic change conditions of fracture parameters under different fracturing construction parameters, and the simulation and optimization parameters comprise discharge capacity, viscosity of fracturing fluids of different types, fracturing fluid amount, different fracturing fluid proportion, propping agent amount, different particle size propping agent proportion, construction sand-fluid proportion, injection program and the like. If a certain fracturing construction parameter combination is found to be capable of obtaining the fracture parameters optimized in the step 3) in the simulation, the corresponding parameter system is the optimized fracturing construction parameter system.
And aiming at the fracturing construction parameters of main fractures with different lengths, the same method and flow are also adopted. For simplicity, it is contemplated that the initial crack should not be too long, otherwise the latter effect will be compromised. For example, 10-20% for the first time, 20-40% for the second time, and 100% for the third time. The number of main cracks can be referred to the result of step 3). And (3) adding the fracturing fluid amounts of different main cracks according to final fracturing construction parameters.
(5) Performing shower hole operation: the first section adopts coiled tubing to carry the perforating gun without bridge plug. Other sections adopt a pumping method to carry the perforating gun and the bridge plug. After the bridge plug is in place, the perforating gun is seated and released, then the perforating gun is lifted up step by step to the preset perforating position of each cluster, and after all the cluster perforating holes are completed, the perforating pipe string is lifted up, and the injection process is reversed.
(6) Acid pretreatment operation: in order to reduce the construction pressure, an acid pretreatment operation is generally performed. Firstly, the rock core of the pilot hole well in the step 1) is used for carrying out compatibility and acid-rock corrosion rate experiments of different acid types and formulas indoors, and therefore an acid type and formula system with good compatibility and relatively highest corrosion rate is selected as the type and formula of the pretreated acid. The acid dosage is generally 10-20m3The upper limit of the acid amount is taken as the acid amount of the section which is constructed firstly, and then the acid amount can be adjusted in real time according to the acid pressure reduction effect along with the construction, so that the acid amount can be reduced or increased.
On the basis, pouring acid injection process with the length of 1-1.5m3The acid injection displacement per minute, after all acid injection is completed, most of the acid remains in the shaft and does not enter the first cluster of perforation positions close to the heel. Then, pour into the main fracturing flow. And increase the discharge capacity to 4-6m3Min to improve the construction efficiency. But after the acid begins to enter the first cluster of perforations near the heel, the displacement of acid should be reduced again to the lower displacement of the previous injection to increase the acid rock reaction time and acid pressure drop effect.
In order to increase the acid entering into different perforation clusters and ensure the synchronous initiation and extension of a plurality of fractures in the section, after the acid enters about 30 percent of the first perforation cluster close to the heel, the acid displacement is increased by 1 to 2 times, such as 6 to 7m3Min and 8-9m3Min, the acid amount is distributed evenly by extracting the amount for several times.
(7) And (3) main crack forming construction: and constructing according to the construction parameters of the first main crack optimized in the step 4). The amount of fracturing fluid at this stage is generally 50-60m3The discharge capacity is generally 3-4m3And/min. After 30-40% of fracturing fluid is injected in the stage, 230-325 mesh fine proppant is started to be added, which can be in a continuous injection mode, and the sand-fluid ratio is 2-4-6%. The liquid amount of each section of sand-liquid ratio can be distributed according to the rest fracturing liquid amount, and can be equally divided, the low sand-liquid ratio can be less, and the high sand-liquid ratio is properly higher. However, if the pressure at the wellhead changes to over 1MPa within 1min, the sand-liquid ratio should be properly reduced.
(8) Stopping the pump: and 7) immediately stopping the pump after the construction in the step 7) is finished, wherein the pump stopping time is 1-2 min. Then, the fracture injection procedure is reversed.
(9) And (5) performing fracturing construction on a second and subsequent main cracks, and repeating the steps 7) to 8). But parameters such as fracturing fluid quantity, discharge capacity, viscosity and the like are increased step by step each time. Specific parameters refer to the fracturing construction parameters of each main fracture optimized in the step 4). Generally, in the construction of subsequent cracks, the discharge capacity can be increased by 20-30% step by step, the fracturing fluid quantity can be increased by 30-40% step by step, and the viscosity can be increased by 10-20% step by step. The sand-liquid ratio can be gradually explored and increased (determined by optimizing fracturing construction parameters, specifically, the influence of different fracturing liquid viscosities under different liquid amounts on the length of a fracture is calculated), and the pump stopping time can be gradually increased by 50-60%.
(10) And (3) main fracture 70-140 mesh proppant injection construction: and (4) injecting according to the construction parameters determined in the step 4). The slippery water with the viscosity of 2-3mPa.s generally accounts for 50-60% of the total amount of the sand-carrying fluid. The injection mode can adopt a slug type adding mode, but if the continuous sand adding does not cause the violent change of the ground construction pressure, the continuous sand adding mode can also be adopted. The sand-liquid ratio of the section can be 2-4-6-8-10-12-14%. The liquid amount of each section of sand-liquid ratio in the early stage can properly exceed 1 wellbore volume so as to observe the pressure response characteristics of the proppant after entering the fracture, and therefore the sand-liquid ratio and the corresponding liquid amount are properly adjusted.
(11) And (3) injecting a 40-70 mesh proppant: and (4) injecting according to the construction parameters determined in the step 4). The slippery water with the viscosity of 6-9mPa.s generally accounts for 20-30% of the total amount of the sand-carrying liquid.
On the basis of the step 10), adding 40-70 meshes of propping agent for construction, and constructing in a long slug mode or a continuous sand adding mode. The sand-liquid ratio is 6-8-10-12-14%. The principle and flow of specific adjustment parameters refer to step 10).
(12) And (3) injecting 30-50 mesh proppant: and (4) injecting according to the construction parameters determined in the step 4). The high-viscosity glue solution with the viscosity of 50-60mPa.s generally accounts for 10-20% of the total amount of the sand-carrying liquid.
The proppant at this stage should be primarily in a single main fracture, typically in a high sand-to-fluid ratio continuous injection mode. The sand-liquid ratio is generally 16-19-22-25-28%. The principle and flow of specific adjustment parameters refer to step 10).
(13) Replacement operation: and (4) designing the displacement liquid amount according to 105-110% of the volume of the current section of the well shaft, and injecting the displacement liquid according to the result determined in the step 4). Wherein, the first 30-40% of liquid is high-viscosity glue solution with the viscosity of 50-60mPa.s, so as to reduce the sand setting effect of the horizontal shaft and provide a smooth clean shaft for the bridge plug under the back-end operation. Then, the injection is replaced by low-viscosity slick water with the viscosity of 2-3mPa.s until the displacement injection is completed.
(14) And (5) performing fracturing construction on other sections, and repeating the steps 5) to 13) until the construction operation of all the sections is completed.
(15) Drilling and plugging, flowback, testing, production and the like are performed according to a conventional process.
ADVANTAGEOUS EFFECTS OF INVENTION
The invention reduces the horizontal main stress difference by utilizing the induced stress brought by forming the artificial crack each time, thereby improving the length of the next artificial crack extending along the direction of the non-maximum main stress, communicating reservoirs in other directions and improving the oil gas productivity. After 2-3 times of fracturing of different scales, the modification range of the artificial fracture in the transverse direction is improved by 4-6 times compared with the conventional fracturing mode.
Detailed Description
The present invention will be further described with reference to the following examples.
Example 1
The well depth of a certain compact sandstone reservoir is 4500 m, and the construction is carried out by the method provided by the invention.
Step (1), parameter evaluation and optimization: the horizontal stress difference of the well is 15.5MPa, the natural fracture development degree is general, the Young modulus is 27.5GPa, and the Poisson ratio is 0.24. The maximum construction discharge capacity is 6m3Permin, 3mPa.s for slickwater 240m39mPa.s requiring 240m for slickwater3240m is needed for 50mPa.s high-viscosity glue solution3。
Step (2), hole-spraying operation: the perforation length is 3m, the hole density is 13 holes/m, and the hole diameter is 10 mm.
Step (3) acid pretreatment operation
1m at the beginning of construction3Injecting acid solution with a discharge capacity of 20 m/min3。
When the first cluster of perforation positions close to the heel part is not reached after all the acid injection is finished; injecting 9 mPas fracturing fluid to replace acid and increasing the displacement of the acid to 4m3Min; after the acid begins to enter the first cluster of perforation positions close to the heel, the displacement of the acid is reduced to the previous displacement of the acid injection again;
after 30% of acid enters the first perforation cluster close to the heel, the displacement of the acid is increased to 2m3/min。
Step (4) is carried out at a speed of 3m3The output volume of the fracturing fluid per minute is injected into the fracturing fluid with the viscosity of 9mPa.s of 60m3Injection of 20m3Then, 230-325 mesh fine proppant is added, and the sand-liquid ratio is 2-4-6% in a continuous injection mode.
And (5) immediately stopping the pump for 2 minutes after the fracturing fluid is injected.
Step (6) then follows the start of the second main crack, at 4m3The discharge volume per minute is injected into fracturing fluid with the viscosity of 15mPa.s of 80m3Injection of 30m3Then carrying 230-325 mesh micro proppant with the sand-fluid ratio of 2-4-6%, and stopping the pump for 5 minutes after the fracturing fluid is injected.
Step (7) then follows the start of the construction of the third main crack, at 6m3The discharge volume per minute is injected into fracturing fluid with the viscosity of 18mPa.s of 100m3Injection of 40m3Then carrying 230-325 mesh micro proppant with the sand-fluid ratio of 2-4-6%, and stopping the pump for 8 minutes after the fracturing fluid is injected.
Step (8) at 6m3The discharge volume per minute is injected into slickwater with the viscosity of 3mPa.s of 240m3Injection of 90m3Then carrying 70-140 mesh proppant with sand-liquid ratio of 2-4-6-8-10-12-14%.
Step (9) at 6m3The discharge volume per minute is injected into the slickwater with the viscosity of 9mPa.s of 180m3Injection of 60m3Then carrying 40-70 mesh proppant with sand-liquid ratio of 6-8-10-12-14%, and continuously adding sand.
Step (10) at 6m3120m of high-viscosity glue solution with the discharge volume per minute and the injection viscosity of 50mPa.s3Injection of 40m3Back-carrying30-40 mesh proppant with sand-liquid ratio of 16-19-22-25-28%.
Step (11) injection of 14m3Replacing with 50 mPas high viscosity glue solution, and injecting 28m low viscosity slickwater with viscosity of 3 mPas3Until the displacement implant is completed.
The radius of the stress reversal area of the well after the 1 st construction is 8.6m, and the steering angle is 10.5 degrees; the radius of the stress reversal area after the 2 nd construction is 15.8m, and the steering angle is 17 degrees; after the 3 rd construction, the radius of the stress reversal area is 21.5m, the steering angle is 25 degrees, the crack steering communicates with reservoirs in other directions, and the yield is increased by 47 percent compared with that before the fracturing.
Example 2
The construction method is used for constructing a compact sandstone reservoir with the well depth of 4200 m.
Step (1), parameter evaluation and optimization: the horizontal stress difference of the well is obtained by experiments and calculation to be 12MPa, the natural fracture development degree is general, the Young modulus is 26GPa, and the Poisson ratio is 0.25. The maximum construction discharge capacity is 8m3Permin, 2mPa.s for slickwater 240m36mPa.s requiring 240m for slickwater3The high-viscosity glue solution of 60mPa.s needs 240m3
Step (2), hole-spraying operation: the perforation length is 6m, the hole density is 16 holes/m, and the hole diameter is 13 mm.
Step (3) acid pretreatment operation
1m at the beginning of construction3Permin displacement is used for injecting acid liquid for 8m3。
When the first cluster of perforation positions close to the heel part is not reached after all the acid injection is finished; injecting 15 mPas of fracturing fluid to replace acid and increasing the displacement of the acid to 6m3Min; after the acid begins to enter the first cluster of perforation positions close to the heel, the displacement of the acid is reduced to the previous displacement of the acid injection again;
after 20% of acid enters the first perforation cluster close to the heel, the displacement of acid is increased to 3m3/min。
Step (4) at 4m3The discharge volume per minute is injected into 50m of fracturing fluid with the viscosity of 6mPa.s3Injection of 20m3Then, the 230-Fine proppant, continuous injection mode, sand-liquid ratio of 2-4-6%.
And (5) immediately stopping the pump for 2 minutes after the fracturing fluid is injected.
Step (6) then follows the start of the second main crack at 6m3The discharge volume per minute is injected into fracturing fluid with the viscosity of 18mPa.s of 60m3Injection of 30m3Then carrying 230-325 mesh micro proppant with the sand-fluid ratio of 2-4-6%, and stopping the pump for 5 minutes after the fracturing fluid is injected.
Step (7) then follows the start of the construction of a third main crack, at 8m3The discharge volume per minute is injected into fracturing fluid with the viscosity of 20mPa.s of 80m3Injection of 40m3Then carrying 230-325 mesh micro proppant with the sand-fluid ratio of 2-4-6%, and stopping the pump for 8 minutes after the fracturing fluid is injected.
Step (8) at 8m3The discharge volume per minute is injected into the slickwater with the viscosity of 2mPa.s of 200m3Injection of 80m3Then carrying 70-140 mesh proppant with sand-liquid ratio of 2-4-6-8-10-12-14%.
Step (9) at 8m3The discharge volume per minute is injected into the slickwater with the viscosity of 6mPa.s of 150m3Injection of 50m3Then carrying 40-70 mesh proppant with sand-liquid ratio of 6-8-10-12-14%, and continuously adding sand;
step (10) at 8m3The output volume per minute is injected into high-viscosity glue solution with the viscosity of 60mPa.s of 100m3Injection of 20m3Then carrying 30-40 mesh proppant with sand-liquid ratio of 16-19-22-25-28%,
step (11) injection of 12m3Replacing with 60 mPas high viscosity glue solution, and injecting 26m with 2 mPas low viscosity slickwater3Until the displacement implant is completed.
The radius of the stress reversal area of the well after the 1 st construction is 9.2m, and the steering angle is 12 degrees; the radius of the stress reversal area after the 2 nd construction is 17.5m, and the steering angle is 20.5 degrees; after the 3 rd construction, the radius of the stress reversal area is 24.6m, the steering angle is 28.5 degrees, the fracture steering communicates with reservoirs in other directions, and the yield is increased by 54.2 percent compared with that before fracturing.
Comparative example
The existing fracture propagation steering technology is one-time temporary plugging steering with a temporary plugging agent, the well depth of a certain compact sandstone reservoir is 4752 m, the horizontal ground stress difference before fracturing is 16.4MPa, the temporary plugging pressure during construction reaches 6.5MPa, and the yield is increased by 18 percent compared with that before fracturing. The stress inversion zone radius was calculated to not exceed 10m and the steering angle was only 12.
Claims (10)
1. A method of controlling the direction of fracture propagation, the method comprising:
step (1) parameter evaluation and optimization;
step (2), performing shower hole operation;
step (3) acid pretreatment operation;
constructing a main crack for forming a seam;
step (5), stopping the pump;
step (6) performing fracturing construction on the second and subsequent main cracks, and repeating the steps (4) to (5);
step (7), injecting 70-140 meshes of propping agent for construction;
step (8), injecting 40-70 mesh proppant for construction;
step (9) injecting 30-50 mesh proppant for construction;
and (10) replacing operation.
2. A method of controlling the direction of fracture propagation according to claim 1, wherein:
the step (1) comprises the following steps: evaluating key reservoir parameters, comprehensively judging and selecting the positions of the section clusters, optimizing fracture parameters and optimizing fracturing construction parameters.
3. A method of controlling the direction of fracture propagation according to claim 1, wherein:
in the step (2), the perforation length is 1-5m, the hole density is 8-20 holes/m, and the hole diameter is 5-20 mm.
4. A method of controlling the direction of fracture propagation according to claim 1, wherein:
in the step (3), the step (c),
the discharge capacity of the injection acid is 1-1.5m3Min, acid dosage is 10-20m3；
When the first cluster of perforation positions close to the heel part is not reached after all the acid injection is finished; injecting 9-15mPa.s of fracturing fluid to replace acid, and increasing the displacement of the acid to 4-6m3Min; after the acid begins to enter the first cluster of perforation positions close to the heel, the displacement of the acid is reduced to the previous displacement of the acid injection again;
after 20-30% of acid enters the first perforation cluster close to the heel, the discharge capacity of the acid is increased step by step 1-2 times, and the discharge capacity increased each time is 0.5-2m3And/min.
5. A method of controlling the direction of fracture propagation according to claim 1, wherein:
in the step (4), low-viscosity fracturing fluid with the viscosity of 9-15mPa.s is injected, and the fluid volume is 50-60m3The discharge capacity is 3-4m3Min; after 30-40% of the liquid is injected, 230-325 mesh fine proppant is added, and the sand-liquid ratio is 2-4-6% in a continuous injection mode.
6. A method of controlling the direction of fracture propagation according to claim 1, wherein:
in the step (5), after the construction in the step 4) is finished, the pump is immediately stopped for 1-2 min.
7. A method of controlling the direction of fracture propagation according to claim 1, wherein:
in the step (6), in the subsequent crack construction, the discharge capacity is gradually increased by 20-30%, the fracturing fluid amount is gradually increased by 30-40%, and the viscosity of the fracturing fluid is gradually increased by 10-20%; the pump stopping time is increased by 50-60% step by step.
8. A method of controlling the direction of fracture propagation according to claim 1, wherein:
in the step (7), slickwater with the viscosity of 2-3mPa.s and 70-140 meshes of propping agent are adopted for injection construction, and the liquid amount accounts for 50-60% of the total amount of the sand-carrying liquid; the sand-liquid ratio is 2-4-6-8-10-12-14%.
9. A method of controlling the direction of fracture propagation according to claim 1, wherein:
in the step (8), slickwater with the viscosity of 6-9mPa.s and 40-70 meshes of propping agent are adopted for injection construction, and the liquid amount accounts for 20-30% of the total amount of the sand carrying liquid; a long slug mode or a continuous sand adding mode, and the sand-liquid ratio is 6-8-10-12-14%.
10. A method of controlling the direction of fracture propagation according to claim 1, wherein:
in the step (9), slickwater with the viscosity of 50-60mPa.s and 30-50 meshes of propping agent are adopted for injection construction, and the liquid amount accounts for 10-20% of the total amount of the sand-carrying liquid; a continuous injection mode, wherein the sand-liquid ratio is 16-19-22-25-28%;
and (10) designing displacement liquid amount according to 110% of 105-plus of the volume of the current section of the well bore, wherein the first 30-40% of liquid amount is high-viscosity glue solution with the viscosity of 50-60mPa.s, and then replacing low-viscosity slick water with the viscosity of 2-3mPa.s for injection until the displacement injection is completed.
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