CN107605451B - A kind of ladder discharge capacity fracturing pump injecting method based on combined perforation - Google Patents

Abstract

The invention discloses a step displacement fracturing pump injection method based on combined perforation, which comprises (1) pumping slick water fracturing fluid with step displacement after perforation, (2) pumping guanidine containing proppant Gel fracturing fluid, (3) pump fresh water to replace, (4) increase the proportion of proppant, and pump guar gum fracturing fluid containing proppant, (5) pump clean water again, so that sand-containing fluid and clean water alternate Pump until the proportion of proppant reaches 20%. (6) Finally, pump a large amount of clean water to fully replace the proppant in the fracture. The invention also includes a wellbore containing perforations of the composite structure. The invention is beneficial to form complex fracture networks in unconventional oil and gas reservoirs with large burial depth, and effectively increase the scale of hydraulic fractures, thereby realizing the purpose of artificially increasing permeability.

Description

A pumping method for stepped displacement fracturing based on combined perforation

technical field

The invention relates to the technical field of unconventional oil and gas reservoir development, in particular to a combined perforation-based step displacement fracturing pump injection method.

Background technique

With the continuous reduction of conventional natural gas resources and the increasing difficulty of development, unconventional natural gas represented by shale gas and coalbed methane is affecting the world's energy structure. my country has abundant reserves of unconventional oil and gas resources and great potential for development. At present, breakthroughs have been made in the exploration and development of unconventional oil and gas resources. need to be resolved.

Theoretical and practical research at home and abroad shows that segmented and clustered volume fracturing technology has become one of the main means of developing unconventional oil and gas reservoirs, and forming complex fracture networks in reservoirs is one of the main goals of volume fracturing. Oriented perforation and spiral perforation are the two most common perforation types in fracturing construction. However, with the increase of reservoir depth, the degree of geological evolution is severe, and the structure and in-situ stress are more complex. The requirements are also higher, and conventional perforation types are often difficult to meet the technical requirements.

At present, the following methods are mainly used for the research on perforation in oil and gas reservoir fracturing:

The single-layer multi-fracture fracturing process is realized with the help of three-dimensional staggered directional perforation technology, including: wellbore optimization, optimization of perforation parameters; optimization of directional perforation type and construction scale; fracturing construction and other steps, the patent uses three-dimensional staggered directional The hole type construction makes the perforation orientations of two adjacent sections different, and the cracks in each section initiate and expand at different azimuths, avoiding the channeling between cracks, realizing more than four fracturing sections in one trip, and improving construction efficiency . However, in unconventional oil and gas reservoirs with large burial depth, especially shale reservoirs with strong heterogeneity, it is often difficult to achieve the desired effect by directional perforation.

Based on the method of quasi-horizontal plane perforation combined with acidification to improve the bottom water reservoir, the perforating gun is lowered to the target interval through the cable or tubing, and then the perforating gun is aligned with the preset perforation plane for perforation, and finally the acid liquid is injected , when the acid liquid enters the perforation on the preset perforation plane, the reservoir near the perforation plane is reformed to ensure that artificial fractures extend inside the oil layer, avoid communication with bottom water, and achieve the purpose of increasing production. However, the acid fracturing provided by this scheme is not suitable for unconventional oil and gas reservoirs, and the reservoir stimulation optimization scheme based on hydraulic fracturing is one of the core technologies for developing unconventional oil and gas reservoirs such as shale gas.

A perforation method for improving the fracturing effect of a casing deviated well, mainly comprising the following steps: firstly, positioning the perforation depth; ;Perform directional perforation; Immediately after the perforation is completed, steps such as sanding and fracturing reconstruction are carried out. The success rate of perforation is improved, there is no spray potential after perforation, and the purpose of optimizing fracture shape and reducing formation fracture pressure is achieved. However, this scheme only optimizes the perforation process, and does not propose an optimization scheme for the perforation structure, and does not involve the pumping method of fracturing fluid.

The fracturing stimulation method based on natural fracture reservoirs mainly includes the use of linear glue liquid to carry out stepped displacement construction on the stimulated reservoir, injecting slick water and the first specification proppant into the stimulated reservoir for three times of plugging, and forming a three-stage hydraulic system. Fractures, thereby improving the fracture complication effect of fracturing in natural fractured reservoirs. However, this plan does not involve the specific displacement of stepped displacement fracturing construction.

At present, research on fracturing of unconventional oil and gas reservoirs seldom involves relatively complex deep unconventional oil and gas reservoirs. As the development depth continues to increase, the structural in-situ stress becomes more and more complex, especially for those with strong heterogeneity and fractures. In developed shale reservoirs, due to the complexity and extension distance of fractures, it is often difficult to guarantee, thus reducing the recovery rate.

Contents of the invention

In view of this, the embodiment of the present invention provides a method for performing stepped displacement fracturing pump injection on reservoirs based on combined perforation. Adaptability, cracks can be effectively supported, and the long-term diversion effect is stable.

The embodiment of the present invention provides a step displacement fracturing pump injection method based on combined perforation, using the wellbore containing combined perforation to perforate the reservoir, and performing step displacement fracturing to the perforated reservoir. Split pump injection, including the following steps:

S1. Set the initial displacement of the slick water fracturing fluid, and use the slick water fracturing fluid to fracture the reservoir to form a first-level hydraulic fracture. During the fracturing process, stepwise increase the displacement of the slick water fracturing fluid, and Slick water fracturing fluids with different displacements are used in turn to fracture the reservoir to form secondary and tertiary hydraulic fractures;

S2. Replace the slick water fracturing fluid with guar gum fracturing fluid, set the displacement of guar gum fracturing fluid, pump guar gum fracturing fluid into the reservoir, the guar gum fracturing fluid contains proppant;

S3. Pumping clean water into the reservoir, displacing the proppant described in step S2 into the fracture;

S4. On the basis of step S2, increase the proportion of the proppant carried in the guar gum fracturing fluid, and pump the guar gum fracturing fluid carrying the proppant into the reservoir;

S5. Repeat steps S3 and S4 until the proportion of proppant carried in the guar gum fracturing fluid reaches 20%, and the displacement of the pumped guar gum fracturing fluid is the same as the final displacement in step S1;

S6. Pump clean water into the reservoir to completely replace the proppant in the fracture.

Further, the wellbore containing combined perforation includes a wellbore, the type of the wellbore is a horizontal well, and it is set in the reservoir, the wellbore is provided with multiple perforation sections in the horizontal section from deep to shallow, and the wellbore Each perforation section includes four perforation clusters, and each perforation cluster includes directional perforation and spiral perforation. The directional perforation is arranged in a straight line from deep to shallow on the horizontal section of the wellbore wall. The spiral perforations are spirally arranged in the horizontal section from deep to shallow on the wall of the wellbore, and the spiral perforations in each cluster start from the starting point of the linear arrangement of directional perforations in the same cluster. The phase angle between the oriented perforation row in the perforation cluster and the directional perforation row in the adjacent perforation cluster is 90°, and the four directional perforation clusters in each perforation section can be distributed in four directions, respectively are horizontal left, horizontal right, vertical up and vertical down.

Further, the phase angle between each helical perforation and adjacent helical perforations in the perforation cluster is 60°, the axial distance between each helical perforation and adjacent helical perforations is 8cm, and each directional perforation The axial distance between the hole and the adjacent directional perforation is 8cm, the distance between the perforation cluster and the adjacent perforation cluster is 8m, the length of each perforation cluster is 1-1.5m, and each meter includes 21 Spiral perforation and directional perforation, the diameter of the spiral perforation and directional perforation is 10.5mm.

Further, in the step S1, the initial displacement of the slick water fracturing fluid is related to the physical properties of the reservoir, the denser the reservoir, the smaller the initial displacement of the slick water fracturing fluid, the better the development of fractures in the reservoir, and the better the slick water fracturing fluid. The larger the initial displacement of water fracturing fluid; the displacement of step-lift slick water fracturing fluid is set according to the construction pressure and the wellhead limit value of the wellbore.

Further, in the step S1, considering the actual pumping capacity of the pump group, from the initial displacement of the slickwater fracturing fluid to the final displacement of the slickwater fracturing fluid, the displacement of the slickwater fracturing fluid has experienced Two step-ups, the first step-up increase is above 100%, and the second step-up increase is 75%-150%. The step increase:

Where R is the step increase, S _n+1 represents the displacement value of the next step, S _n represents the displacement value of the previous step, n=1,2.

Further, the initial displacement of the slick water fracturing fluid is 2-4m ³ /min, after the first lifting, the displacement of the slick water fracturing fluid is 6-8m ³ /min, after the second lifting , the displacement of the slick water fracturing fluid is 12-16m ³ /min.

Further, the step S1 includes the following steps:

S1.1. Set the initial displacement of the slick water fracturing fluid, and use the slick water fracturing fluid to fracture the reservoir to obtain a first-level hydraulic fracture;

S1.2. On the basis of step S1.1, the displacement is increased, and the reservoir is fractured with slick water fracturing fluid to obtain secondary hydraulic fractures;

S1.3. On the basis of step S1.2, the displacement is increased, and the reservoir is fractured with slick water fracturing fluid to obtain three-stage hydraulic fractures.

Further, the slick water fracturing fluid is mainly made of the following raw materials in mass percentage: drag reducer 0.1%, drainage aid 0.3%, clay stabilizer 1%; the guar gum fracturing fluid is mainly made of the following mass percentages: Raw materials in percent content: 0.5% guar gum, 0.5% KCl, 0.3% clay stabilizer, 0.5% drainage aid, 0.3% organic boron crosslinking agent; the ratio of the slick water fracturing fluid is slick water pressure 45%-50% of the sum of fracturing fluid and guar gum fracturing fluid; the proppant is medium-density ceramsite with a particle size of 0.425-0.85mm and a bulk density of 1.75g/cm ³ , and the performance index is required to reach SY/T The indicators specified in the 5108-2006 standard.

Further, in the step S2, the displacement of the guar gum fracturing fluid is the same as the final displacement of the last stage in the step S1, which is 12-16m ³ /min, and the specific displacement value is related to the pumping capacity of the surface pump set Relevant, and keep this displacement constant during the process of pumping guar gum fracturing fluid and clear water replacement, the initial proportion of the proppant carried by the guar gum fracturing fluid is 5%.

Further, in the step S3, the liquid volume of the pump injection clear water is the same as the liquid volume of the guar gum fracturing fluid carrying the proppant, and the liquid volume of the guar gum fracturing fluid carrying the proppant is 40- 60m ³ .

Further, in the step S4, the proportion of the proppant carried in the guar gum fracturing fluid is increased by 1% each time.

Further, in the step S6, the liquid volume of pumping clean water into the reservoir is more than 100 m ³ .

Compared with the prior art, the present invention has the following beneficial effects:

(1) Based on the principle of energy conversion, the pumping method of stepped displacement fracturing in staged cluster fracturing was optimized, and the specific displacement value of stepped displacement fracturing was given in combination with the actual situation of the fracturing construction site , it has strong adaptability to deep unconventional oil and gas reservoirs with complex structural in-situ stress, fractures can be effectively supported, and the long-term diversion effect is stable.

(2) Using the wellbore with combined perforation for fracturing can not only increase the length of hydraulic fractures, but also effectively avoid the disadvantage of forming hydraulic fractures only near the wellbore end in deep oil and gas reservoirs during the fracturing process, and the combined perforation Perforation can produce liquid in all directions, and it has good adaptability to deep reservoirs with complex structural stress directions. In addition, the dispersion of perforation azimuths diversifies the positional relationship between hydraulic fractures and natural fractures, increasing the probability of hydraulic fractures penetrating natural fractures, thereby increasing the scale of fractures.

Description of drawings

Fig. 1 is a schematic diagram of a wellbore with combined perforation in a method of performing stepped displacement fracturing pump injection on a reservoir based on combined perforation according to the present invention. Among them, 1-wellbore, 2-perforation cluster, 21-directional perforation, 22-helical perforation, A is the horizontal section, B is the vertical well section, the part near the end of A is the depth of the well, and the part near the end of B is the shallow part of the well ;

Fig. 2 is a schematic diagram of a wellbore section, which is used to represent a wellbore orientation;

Fig. 3 is a flow chart of a method for pumping injection of stepped displacement fracturing to reservoirs based on combined perforation.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the embodiments of the present invention will be further described below in conjunction with the accompanying drawings.

Taking a shale gas fracturing well in the Sichuan Basin as an example, the embodiment of the present invention provides a method for performing stepped displacement fracturing pumping on reservoirs based on combined perforation. The method should at least include: The perforated wellbore is used to perforate the reservoir, the perforation method and parameters are optimized; steps such as step displacement fracturing and pumping are carried out to the perforated reservoir.

The basic parameters of the reservoir are: reservoir thickness 38m, temperature 95°C, porosity 4.28%, formation pressure 38.94MPa, formation pressure coefficient 1.55, closure pressure 54.8MPa, average Poisson's ratio of reservoir shale 0.17, average Young's modulus The volume is 34.25 GPa.

The main wellbore parameters are: vertical depth of 3973.33m, horizontal section length of 1625.21m, a total of three casings, the outer diameter of the three casings in the horizontal section is 139.7mm, and the wellbore direction is parallel to the bedding plane.

According to the logging interpretation, construction requirements, HSE and well control requirements, and according to the physical properties of the reservoir, the development of structural planes, and the difference in horizontal ground stress, the perforation and fluid injection operations should be arranged reasonably.

Please refer to Figure 1, the wellbore with combined perforation includes the wellbore 1, which is a horizontal well and is set in the reservoir, and the wellbore 1 is provided with multiple perforations in the horizontal section from deep to shallow Each perforation section includes four perforation clusters 2. The specific number and length of perforation clusters 2 should be determined according to the physical properties of the reservoir and the setting conditions of the packer. In the embodiment, each perforation section The length of the cluster 2 is 1-1.5m, the distance between the perforation cluster 2 and the adjacent perforation cluster 2 is 8m, the directional perforation 21 in the perforation cluster 2 and the adjacent perforation cluster 2 The phase angle between the directional perforations 21 is 90°.

Each perforation cluster 2 includes directional perforation 21 and helical perforation 22. In one embodiment, each meter includes 21 helical perforations 21 and directional perforation 22. The helical perforation 22 and directional perforation 21 The pore diameter of the combined perforation is 10.5mm. The combined perforation combines the advantages of the two perforations, which not only helps to increase the extension length of the main fracture, but also ensures the width of the fracture. It has good adaptability and is conducive to expanding the scale of hydraulic fractures.

Please refer to Fig. 2, the directional perforations 21 are arranged in a straight line from deep to shallow on the horizontal section of the wall of the wellbore 1, and the axial distance between each directional perforation in the perforation cluster 2 and the adjacent directional perforation is 8cm , the directional perforations 21 in each perforation section may cover vertically upward, vertically downward, horizontally left and horizontally right, ie positive S and positive N directions.

The spiral perforations 22 are arranged spirally in the horizontal section from deep to shallow along the circumferential direction on the wall of the wellbore 1, and the spiral perforations 22 start from the starting point where the same cluster of directional perforations 21 are arranged in a straight line as the starting point. The phase angle between each helical perforation 22 and the adjacent helical perforation 22 in cluster 2 is 60°, and the axial distance between each helical perforation 22 and the adjacent helical perforation 22 is 8cm. , to reduce the influence of stress shadowing, the spacing between the perforation axes should be appropriately increased, so it is set to 8cm.

The step displacement fracturing pump injection process is for a certain section of the fracturing process, and the same method can be used for other sections to fracturing, or fine-tuning can be made according to the actual situation.

Select Φ60.32mm tubing and KQ65/70 type lower suspension wellhead, and adopt the annular injection fracturing process for fluid injection. well to the bottom of the artificial well. Pressurize less than 30KN when encountering resistance in the middle of the lower pipe string; prepare clean water not less than 2 times the volume of the wellbore on site, and backwash the well with a displacement of not less than 0.65m ³ /min until the water quality of the inlet and outlet is consistent. Full wellbore casing pressure test 30MPa, 30min pressure drop is less than 0.5MPa is qualified; tubing ball throwing, pressurized 25MPa, 30min pressure drop is less than 0.5MPa is qualified; the wellbore string is proposed, the hole gun type is SYD-102, and then KQ65 is installed /70 X-mass tree.

Please refer to Figure 3, step displacement fracturing pump injection includes the following steps: S1. Set the initial displacement of slick water fracturing fluid, the initial displacement of slick water fracturing fluid is related to the physical properties of the reservoir, the tighter the reservoir , the smaller the initial displacement of the slick water fracturing fluid, the better the fracture development of the reservoir, and the larger the initial displacement of the slick water fracturing fluid; During the fracturing process, the displacement of the slick-water fracturing fluid is stepped up to form second and third-stage hydraulic fractures, and the displacement of the slick-water fracturing fluid is set according to the construction pressure and the wellhead limit value of the wellbore, from From the initial displacement of the slick water fracturing fluid to the final displacement of the slick water fracturing fluid, the displacement of the slick water fracturing fluid has undergone two step-ups, the first step-up increase is above 100%, and the second step The step-up increase is 75%-150%; the calculation formula for the step-up increase is as follows:

Where R is the step increase, S _n+1 represents the displacement value of the next step, S _n represents the displacement value of the previous step, n=1,2.

Slippery water fracturing fluids with different displacements are used sequentially to fracture the reservoir.

Based on the principle of energy conversion and combined with hydraulic fracturing physical simulation experiments to analyze the stepped displacement fracturing process, it is found that when the pumping displacement in the next stage reaches about twice that of the previous stage, new hydraulic fractures will often be generated, otherwise, The slick water fracturing fluid will only leak from the original fractures, which will temporarily increase the fracture width. However, considering the actual situation of the current hydraulic fracturing pump equipment, three displacements are designed, and the step-up stage is more in line with actual.

The slick water fracturing fluid is mainly made of the following raw materials in mass percentage: 0.1% drag reducer, 0.3% drainage aid, and 1% clay stabilizer.

Specifically, the step S1 includes the following steps:

S1.1. Set the initial displacement of the slick water fracturing fluid, preferably 2-4m ³ /min, and use the slick water fracturing fluid to fracture the reservoir to obtain a first-order hydraulic fracture;

S1.2. On the basis of step S1.1, increase the displacement for the first time, preferably 6-8m ³ /min, and use slick water fracturing fluid to fracture the reservoir to obtain secondary hydraulic fractures;

S1.3. On the basis of step S1.2, increase the displacement for the second time, preferably 12-16m ³ /min, and use slick water fracturing fluid to fracture the reservoir to obtain three-stage hydraulic fractures.

S2. replace the slick water fracturing fluid with guar gum fracturing fluid, set the displacement of guar gum fracturing fluid, the displacement of guar gum fracturing fluid is the same as the final displacement of the last stage in step S1, preferably 12-16m ³ /min, the specific displacement value is related to the pumping capacity of the surface pump set, and this displacement is kept constant during the process of pumping guar gum fracturing fluid and water replacement, the guar gum fracturing fluid The proppant-carrying proppant is pumped into fractures of the reservoir, the volume of the guar gum fracturing fluid carrying the proppant is 40-60m ³ per pumping, and the initial proportion of the guar gum fracturing fluid carrying the proppant is preferably 5%.

Guar gum fracturing fluid is mainly made of the following raw materials in mass percentage: 0.5% guar gum, 0.5% KCl, 0.3% clay stabilizer, 0.5% drainage aid, 0.3% organic boron crosslinking agent; the slick water The proportion of fracturing fluid is 45%-50% of the sum of slick water fracturing fluid and guar gum fracturing fluid.

The proppant is medium-density ceramsite, the particle size is 0.425-0.85mm, and the bulk density is 1.75g/cm ³ , and the performance index is required to meet the index specified in the SY/T 5108-2006 standard.

S3. Pump clean water into the reservoir, and replace the proppant described in step S2 in the fracture; ensure that the fracture is fully supported; the liquid volume of the pumped clean water is the same as the liquid volume of the guar gum fracturing fluid carrying the proppant The same, that is, the liquid volume is 40-60m ³ .

S4. Pump the guar gum fracturing fluid carrying proppant into the reservoir, and increase the proportion of proppant carried in the guar gum fracturing fluid on the basis of step S2; each time the guar gum fracturing fluid carries proppant increased by 1%;

S5. Repeat steps S3 and S4 until the proportion of proppant carried in the guar gum fracturing fluid reaches 20%;

S6. Finally, pump a large amount of clean water into the reservoir until the proppant is completely replaced in the fracture.

The liquid volume of pumping clean water into the reservoir is more than 100m ³ to ensure the maximum degree of reservoir reconstruction.

Microseismic monitoring results show that the scale of fractures is significantly larger than before optimization. After the fracturing operation is completed, the initial average gas production is 1.5×10 ⁴ m ³ /d, which is 13.58% higher than that of the spiral perforated wells in the same block.

Based on the principle of energy conversion, the present invention optimizes the pumping method of stepped displacement fracturing in segmented cluster fracturing, and has strong adaptability to deep unconventional oil and gas reservoirs with complex structural stress, and the fractures can be effectively supported. The long-term diversion effect is stable; the combined perforation can not only increase the length of hydraulic fractures, but also effectively avoid the disadvantages of forming hydraulic fractures only near the wellbore during the fracturing process of deep oil and gas reservoirs. Perforation can produce fluid in all directions, and it has good adaptability to deep reservoirs with unclear structural stress directions. In addition, the dispersion of perforation orientation makes the positional relationship between hydraulic fractures and natural fractures more diverse. Increases the chance of hydraulic fractures penetrating natural fractures, thereby increasing the size of the fracture.

The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structures and method transformations made by using the description of the present invention and the contents of the accompanying drawings, or directly or indirectly used in other related technical fields, are all The same reasoning is included in the patent protection scope of the present invention.

In this article, the orientation words involved, such as front, back, upper, lower, deep, shallow, etc., are defined by the positions among the parts in the drawings, just for the clarity and convenience of expressing the technical solution. It should be understood that the use of the location words should not limit the scope of protection claimed in this application.

In the case of no conflict, the above-mentioned embodiments and features in the embodiments herein may be combined with each other.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within range.

Claims (11)

1. A step displacement fracturing pump injection method based on combined perforation, characterized in that, the wellbore containing combined perforation is used to perforate the reservoir, and the wellbore containing combined perforation includes wellbore, The type of the wellbore is a horizontal well, and it is set in the reservoir. The wellbore is provided with multiple perforation sections from deep to shallow in the horizontal section. Each perforation section of the wellbore includes four perforation clusters. Each perforation cluster includes directional perforation and spiral perforation. The directional perforation is arranged in a straight line from deep to shallow on the horizontal section of the wellbore wall, and the spiral perforation is arranged on the horizontal section of the wellbore wall. Arranged spirally in the circumferential direction from deep to shallow, the spiral perforations in each cluster start from the starting point of the linear arrangement of directional perforations in the same cluster as the starting point, and the directional perforation columns in the perforation cluster The phase angle between the oriented perforation clusters in Fig. Straight down, step-displacement fracturing pumping into the perforated reservoir, including the following steps: S1. Set the initial displacement of the slick water fracturing fluid, and use the slick water fracturing fluid to fracture the reservoir to form a first-level hydraulic fracture. During the fracturing process, stepwise increase the displacement of the slick water fracturing fluid, and Slick water fracturing fluids with different displacements are used in turn to fracture the reservoir to form secondary and tertiary hydraulic fractures; S2. Replace the slick water fracturing fluid with guar gum fracturing fluid, set the displacement of guar gum fracturing fluid, pump guar gum fracturing fluid into the reservoir, the guar gum fracturing fluid contains proppant; S3. Pumping clean water into the reservoir, displacing the proppant described in step S2 into the fracture; S4. On the basis of step S2, increase the proportion of the proppant carried in the guar gum fracturing fluid, and pump the guar gum fracturing fluid carrying the proppant into the reservoir; S5. Repeat steps S3 and S4 until the proportion of proppant carried in the guar gum fracturing fluid reaches 20%, and the displacement of the pumped guar gum fracturing fluid is the same as the final displacement in step S1; S6. Pump clean water into the reservoir to completely replace the proppant in the fracture. 2. The combined perforation-based step displacement fracturing pumping method according to claim 1, wherein the phase angle between each helical perforation in the perforation cluster and the adjacent helical perforation is 60°, the axial distance between each spiral perforation and the adjacent spiral perforation is 8cm, the axial distance between each directional perforation and the adjacent directional perforation is 8cm, the perforation cluster and the adjacent perforation The distance between the hole clusters is 8m, and the length of each perforation cluster is 1-1.5m. Each meter includes 21 spiral perforations and directional perforations. The diameter of the spiral perforations and directional perforations is 10.5mm. 3. The combined perforation-based step displacement fracturing pumping method according to claim 1, characterized in that, in the step S1, the initial displacement of the slickwater fracturing fluid is related to the physical properties of the reservoir, The denser the reservoir, the smaller the initial displacement of the slick water fracturing fluid, the better the fracture development of the reservoir, and the greater the initial displacement of the slick water fracturing fluid; Set with the wellhead limit value of the wellbore. 4. The combined perforation-based step displacement fracturing pumping method according to claim 1, characterized in that, in the step S1, considering the actual pumping capacity of the pump set, from the slick water fracturing fluid From the initial displacement of the slick water fracturing fluid to the final displacement of the slick water fracturing fluid, the displacement of the slick water fracturing fluid has undergone two step increases, the first step increase is above 100%, and the second step increase is 75%. %-150%, the step increase: Where R is the step increase, S _n+1 represents the displacement value of the next step, S _n represents the displacement value of the previous step, n=1,2. 5. The combined perforation-based step displacement fracturing pumping method according to claim 4, characterized in that the initial displacement of the slick water fracturing fluid is 2-4 m ³ /min, and the first time After lifting, the displacement of the slick water fracturing fluid is 6-8 m ³ /min, and after the second lifting, the displacement of the slick water fracturing fluid is 12-16 m ³ /min. 6. The combined perforation-based step displacement fracturing pumping method according to claim 1, characterized in that the step S1 comprises the following steps: S1.1. Set the initial displacement of the slick water fracturing fluid, and use the slick water fracturing fluid to fracture the reservoir to obtain a first-level hydraulic fracture; S1.2. On the basis of step S1.1, the displacement is increased, and the reservoir is fractured with slick water fracturing fluid to obtain secondary hydraulic fractures; S1.3. On the basis of step S1.2, the displacement is increased, and the reservoir is fractured with slick water fracturing fluid to obtain three-stage hydraulic fractures. 7. The combined perforation-based step displacement fracturing pumping method according to claim 1, wherein the slickwater fracturing fluid is mainly made of the following raw materials in mass percentage: drag reducer 0.1%, drainage aid 0.3%, clay stabilizer 1%; the guar gum fracturing fluid is mainly made of the following raw materials in mass percentage: guar gum 0.5%, KCl 0.5%, clay stabilizer 0.3%, auxiliary Discharge agent 0.5%, organoboron crosslinking agent 0.3%; the ratio of the slick water fracturing fluid is 45%-50% of the sum of the slick water fracturing fluid and guar gum fracturing fluid; the proppant is medium density Ceramsite, the particle size is 0.425-0.85mm, the bulk density is 1.75g/cm ³ , and the performance index is required to meet the index specified in the SY/T 5108-2006 standard. 8. The combined perforation-based step displacement fracturing pump injection method according to claim 1, characterized in that, in the step S2, the displacement of the guar gum fracturing fluid is the same as that of the last stage in the step S1. The final displacement is the same, which is 12-16m ³ /min. The specific displacement value is related to the pumping capacity of the surface pump set, and this displacement will remain unchanged during the process of pumping guar gum fracturing fluid and water replacement. The initial ratio of proppant carried by the guar gum fracturing fluid is 5%. 9. The combined perforation-based step displacement fracturing pumping method according to claim 1, characterized in that, in the step S3, the liquid volume of the pumped clear water is equal to the pressure of the guar gum that carries the proppant. The volume of fracturing fluid is the same, and the volume of guar gum fracturing fluid carrying proppant is 40-60m ³ per pump. 10. The combined perforation-based step displacement fracturing pumping method according to claim 1, characterized in that in step S4, the proportion of proppant carried in the guar gum fracturing fluid is increased by 1% each time . 11. The combined perforation-based step displacement fracturing pumping method according to claim 1, characterized in that, in the step S6, the volume of clean water pumped into the reservoir is more than 100 m ³ .