Quasi-horizontal well fracturing process for shale oil directional well

Abstract

The invention discloses a horizontal well fracturing process for a shale oil directional well. The method comprises the following steps that S1, according to geological and engineering data of the fault block type shale oil reservoir, in combination with crack parameters of a block early-stage fractured well, three-dimensional layering and clustering and fracturing process main body parameters of a directional well are determined; s2, injecting an acid solution into the reservoir in a large-displacement manner to perform acid pretreatment; s3, low-viscosity fracturing fluid injection is switched, and the displacement is rapidly increased; s4, according to reverse design, different construction pressure windows serve as the core, a three-section type pressure control and displacement adjusting pressure stabilizing sand adding mode is adopted, and single-layer fracturing sand adding is completed; and S5, according to the steps, fracturing sand adding of the remaining interval of the single well is completed. The method has the advantages that the fracturing transformation seam length of the shale oil directional well is greatly increased, the seam net supporting effect and the seam net seam control reserve of the directional well are improved, the testing yield after fracturing is high, the stable production time is long, and high-benefit development of the directional well in a complex structure area is achieved.

Description

Technical Field

[0001] The invention relates to an unconventional oil and gas production enhancement and transformation technology, in particular to a shale oil directional well quasi-horizontal well fracturing process, belonging to the technical field of oil production. Background Art

[0002] At present, the development theory and technology of continental shale oil in China are in the initial stage, and there is no mature development model. The eastern and western wings of the Qintong Sag in the Subei Basin are complex structural areas with developed faults and large formation dips. The length of the fault block does not exceed 2km, the width does not exceed 1km, and the area is generally less than 2km. 2 , small faults and natural fractures are developed, and the conditions for implementing horizontal wells above 1000m are not met. The wells are arranged along the fault direction, but the effect of the fracturing network is difficult to guarantee because it is parallel to the direction of the maximum horizontal principal stress; the drilling rate of the sweet spot when arranging wells through the fault is low, and the fracturing section needs to avoid the fault position, which affects the economic benefits. The drilling and completion cycle of horizontal well development is long and the investment is large. The height of the fracturing fracture is about 30m, the vertical resource utilization rate is not high, and the development efficiency of horizontal wells is not ideal. Based on the characteristics of fault-block shale reservoirs such as "steep formation, narrow fault blocks, developed laminations and fractures, small stress difference coefficient, and high brittleness index", the efficient development of continental shale oil fault-block shale reservoirs faces many difficulties. There is no mature development method for this type of shale oil. It is of great significance to create a shale oil directional well quasi-horizontal well fracturing technology. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a shale oil directional well pseudo-horizontal well fracturing process which can effectively increase the fracture length, improve the fracture network support effect and fracture network quality, and improve the shale oil production effect.

[0004] In order to solve the above technical problems, the shale oil directional well quasi-horizontal well fracturing process of the present invention comprises the following steps: S1: According to the geological and engineering data of fault-block shale reservoirs and the previous fracturing fracture parameters of the block, the three-dimensional stratification and clustering of directional wells and the main parameters of the fracturing process are determined; Furthermore, in this step, based on the existing reservoir physical properties and engineering parameters in the region, combined with the fracture height data monitored by the fractured wells, the three-dimensional stratification and clustering parameters of the directional wells are determined; Furthermore, in the step, the directional well preferably has 3-4 clusters of single-layer perforations.

[0005] S2: injecting a large amount of acid into the reservoir for acid pretreatment; Furthermore, in this step, the amount of acid used per layer is 20-30m 3 , pumping capacity 3-5m 3 / min; Furthermore, the acid solution in this step includes hydrochloric acid, a high temperature corrosion inhibitor, a drainage aid, a clay stabilizer, and an iron ion stabilizer; S3: Switch to low-viscosity fracturing fluid injection and quickly increase the displacement; Furthermore, in this step, the injection of low-viscosity fracturing fluid is switched to quickly increase the displacement under the construction pressure limit to form a high fracture pressure, which promotes the simultaneous fracture and fluid injection of multiple perforation clusters; S4: Reverse design, with different construction pressure windows as the core, adopts three-stage control of construction pressure, adjustment of displacement, constant pressure and sand adding mode to complete single-layer fracturing and sand adding; In this step, the first stage mode: Adjust the pump injection and displacement to control the pressure window at 4-5MPa; a. Pump low-viscosity fracturing fluid with small-size proppant to fill micro-cracks, and add low-concentration 0.1% synergist in slug injection, with a sand-to-liquid ratio of 2%-10%; b. Pump in medium-viscosity fracturing fluid carrying medium-sized proppant to fill branch fractures, with a sand-to-liquid ratio of 2%-10%; c. During the pumping process, the automatic pressure-stabilizing pumping system is put into use and the pressure fluctuation amplitude is set. When the pressure fluctuation reaches the upper and lower limits, the step adjustment of the displacement is triggered to keep the pressure stable; d. Complete 1 / 3 of the total liquid volume; Second stage mode: Adjust the pumping volume, reduce the construction pressure, and control the pressure window to 10-14MPa; a. Pump in medium-viscosity fracturing fluid with medium-sized proppant to fill micro-cracks, with a sand-to-liquid ratio of 7%-10%; b. Pump in medium-high viscosity fracturing fluid carrying medium-large particle proppant to fill the main fracture, with a sand-to-liquid ratio of 2%-5%; c. During the pumping process, the automatic pressure-stabilizing pumping system is put into use and the pressure fluctuation amplitude is set. When the pressure fluctuation reaches the upper and lower limits, the step adjustment of the displacement is triggered to keep the pressure stable; d. Complete 2 / 3 of the total liquid volume; Phase 3 Mode: Adjust the pumping volume, reduce the construction pressure, and control the pressure window to 17-20MPa; a. Pump medium-high viscosity fracturing fluid with medium-sized proppant to fill the main fracture, with a sand-to-liquid ratio of 4%-5%; b. Pump in high-viscosity fracturing fluid and tail ceramsite proppant to establish a high-conductivity channel at the seam mouth, with a sand-to-liquid ratio of 4%-5%; c. During the pumping process, the automatic pressure-stabilizing pumping system is put into use and the pressure fluctuation amplitude is set. When the pressure fluctuation reaches the upper and lower limits, the step adjustment of the displacement is triggered to keep the pressure stable; d. Complete the single layer of sand and liquid volume.

[0006] S5: Referring to the above steps, complete the fracturing and sanding of the remaining layers of the single well.

[0007] Furthermore, the proppant in step S4 uses multi-grade particle size proppant, including 100 / 200 mesh proppant, 70 / 140 mesh proppant, 40 / 70 mesh proppant, 30 / 50 mesh or larger particle size 20 / 40 mesh proppant.

[0008] Furthermore, the proportion of the proppants of each particle size is as follows: the volume of small particle size proppant: the volume of medium particle size proppant: the volume of large particle size proppant = 2:3:5.

[0009] Furthermore, the low-viscosity fracturing fluid is a drag reducer with a concentration of 0.08-0.12%; the medium-viscosity fracturing fluid is a drag reducer with a concentration of 0.13-0.18%; the medium-high-viscosity fracturing fluid is a drag reducer with a concentration of 0.19-0.24%; and the high-viscosity fracturing fluid is a drag reducer with a concentration of 0.25-0.30%.

[0010] The advantages of the present invention are: Through multi-step pressure reduction and regulation, pressure stabilization, variable viscosity and efficient sand carrying of tertiary proppant, and continuous construction with all-electric equipment, a new "quasi-horizontal well" fracturing process for shale oil directional wells has been formed. The idea of ​​establishing a full-process automatic pressure-stabilizing pumping system, plug-type injection of functional fracturing fluid, and low-sand ratio long-distance migration support has effectively increased the length of the shale oil directional well fracturing transformation fracture, improved the fracture network support effect and fracture network quality, thereby greatly increasing the fracture-controlled reserves of shale oil directional wells. The test output of the quasi-horizontal well fracture network after fracturing is high, achieving high-efficiency development of directional wells in complex structures and improving the purpose of shale oil production. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a single-layer fracturing construction curve diagram of shale oil directional well A in the present invention. DETAILED DESCRIPTION

[0012] The shale oil directional well quasi-horizontal well fracturing process of the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. Among them, the fracturing equipment unit used in this embodiment of the present invention is preferably a fully electric pumping system; a fully electric pump, an online lubrication system, and fully automatic sand conveying equipment are selected, and an automatic pressure-stabilizing pumping system is put into use to meet the requirements of large single-stage liquid volume (>12,000 cubic meters) of directional well fracturing, long operation time (>14 hours), large construction displacement (>16 cubic meters / minute), and continuous injection.

[0013] The shale oil directional well quasi-horizontal well fracturing process of the present invention comprises the following steps: S1: Based on the geological and engineering data of shale reservoirs in complex structural areas, combined with the previous fracturing fracture parameters of the block, simulation software is used to optimize and determine the three-dimensional stratification and clustering of directional wells and the main parameters of the fracturing process; Furthermore, in this step, based on the reservoir physical properties and engineering parameters of the structurally complex area, combined with the fracture height data monitored by the fractured wells, the three-dimensional stratification and clustering parameters of the directional wells are determined; Furthermore, in the step, 3-4 clusters of perforations are performed in a single layer of a directional well, which is 2-4 clusters less than that in a single section of a horizontal well, thereby increasing the flow rate of a single cluster and promoting the extension of the fracture length; At the same time, in this step, conventional reservoir geological modeling and fracture extension simulation software is used to import geological and engineering data, simulate the fracture system, obtain the fracture extension distribution corresponding to different pumping stages, and combine the fracture length data monitored in the fractured wells to optimize the main fracturing process parameters, including construction displacement, single layer liquid volume, proppant dosage, etc. The specific operations simulated with mature professional software are known to ordinary technicians in this field and will not be repeated here.

[0014] S2: injecting acid into the reservoir in large quantities through the wellbore for acid pretreatment; Furthermore, in this step, the amount of acid used per layer is 20-30m 3 , pumping capacity 3-5m 3 / min; Furthermore, the acid solution in this step includes hydrochloric acid, a high temperature corrosion inhibitor, a drainage aid, a clay stabilizer, and an iron ion stabilizer; S3: Switch to low-viscosity fracturing fluid injection and quickly increase the displacement; Furthermore, in this step, the displacement is increased rapidly under the construction pressure limit to form a high fracture pressure, and the shale reservoir is opened under the high fracture pressure, so that multiple perforation clusters are fractured and fluid is injected synchronously; compared with the twisted and complex fractures formed under low fracture pressure, the main fractures generated under high fracture conditions will reduce the construction pressure and the difficulty of adding sand; S4: The reverse design is centered on different construction pressure windows, and adopts a three-stage pressure control, pressure regulation and pressure stabilization sand adding mode to complete single-layer fracturing and sand adding; In this step, the first stage mode: Adjust the pump injection and displacement to control the pressure window at 4-5MPa; a. Pump low-viscosity fracturing fluid with small-size proppant to fill micro-cracks, and add low-concentration 0.1% synergist in slug injection, with a sand-to-liquid ratio of 2%-10%; b. Pump in medium-viscosity fracturing fluid with medium-sized proppant to fill branch fractures, with a sand-to-liquid ratio of 2%-10%; c. During the pumping process, the automatic pressure-stabilizing pumping system is put into use and the pressure fluctuation amplitude is set. When the pressure fluctuation reaches the upper and lower limits, the step adjustment of the displacement is triggered to keep the pressure stable; d. Complete 1 / 3 of the total liquid volume; Second stage mode: Adjust the pumping volume, reduce the construction pressure, and control the pressure window to 10-14MPa; a. Pump in medium-viscosity fracturing fluid with medium-sized proppant to fill micro-cracks, with a sand-to-liquid ratio of 7%-10%; b. Pump in medium-high viscosity fracturing fluid carrying medium-large particle proppant to fill the main fracture, with a sand-to-liquid ratio of 2%-5%; c. During the pumping process, the automatic pumping system based on the intelligent adjustment algorithm performs precise control to keep the construction pressure stable; d. Complete 2 / 3 of the total liquid volume; Phase 3 Mode: Adjust the pumping volume, reduce the construction pressure, and control the pressure window to 17-20MPa; a. Pump medium-high viscosity fracturing fluid with medium-sized proppant to fill the main fracture, with a sand-to-liquid ratio of 4%-5%; b. Pump in high-viscosity fracturing fluid and tail ceramsite proppant to establish a high-conductivity channel at the seam mouth, with a sand-to-liquid ratio of 4%-5%; c. During the pumping process, the automatic pumping system based on the intelligent adjustment algorithm performs precise control to keep the construction pressure stable; d. Complete the single layer of sand and liquid volume.

[0015] Furthermore, the fracturing fluid in step S4 includes a high-efficiency drag reducer, a composite anti-swelling agent, a bactericide, and a surfactant. The proppant in step S4 can use a multi-grade particle size proppant, including 100 / 200 mesh proppant, 70 / 140 mesh proppant, 40 / 70 mesh proppant, 30 / 50 mesh or a larger particle size of 20 / 40 mesh proppant. Based on the differences in the seam network, the preferred proportion of proppants of each particle size is small particle size proppant volume: medium particle size proppant volume: large particle size proppant volume = 2:3:5.

[0016] Furthermore, low-viscosity fracturing fluid is a drag reducer with a concentration of 0.08-0.12%; medium-viscosity fracturing fluid is a drag reducer with a concentration of 0.13-0.18%; medium-high-viscosity fracturing fluid is a drag reducer with a concentration of 0.19-0.24%, and high-viscosity fracturing fluid is a drag reducer with a concentration of 0.25-0.30%; and the simultaneous plug-in injection of enhancers effectively improves the range of the fracturing fluid's synergistic effect.

[0017] Furthermore, in the step S4, an automated pressure-stabilizing pumping system is put into use, and based on the construction pressure change, the pressure fluctuation amplitude is set to ±0.5 MPa; when the pressure fluctuation reaches the upper and lower limits, the step adjustment of the displacement is triggered by 0.1 m 3 / min, the construction pressure fluctuates within a narrow range and tends to be stable.

[0018] From the above, it can be seen that in the first stage of fracturing, the amount of pumped fracturing fluid is basically 33% of the total designed liquid volume of a single layer, and in the second stage, the pumping basically completes the fracturing of 66% of the total designed liquid volume of a single layer; in the third stage, fracturing is carried out until the total designed liquid volume of a single layer is completed; through the high pressure and large displacement in the first stage, the intra-layer fracture height of the directional well can be expanded, and the construction pressure is gradually reduced in the second and third stages, and the pressure is stabilized to control the complexity of the fracture, which is conducive to the distal extension of the main fracture, and the idea of ​​​​quasi-horizontal well long fracture fracturing of the directional well is achieved. Therefore, an innovative three-stage pressure control mode is used to gradually reduce the construction pressure, adjust the displacement, stabilize the pressure and add sand, ensure the transformation effect and save energy and reduce consumption, and at the same time reduce the failure rate of fracturing equipment under large liquid volume and high pressure for a long time.

[0019] S5: Referring to the above steps, complete the fracturing and sanding of the remaining layers of the single well.

[0020] Through this plan: adopt the three-stage pressure control mode construction, put into use the automatic pressure-stabilizing pump injection system, adjust the pressure-stabilizing construction in real time, avoid activating more bedding fractures and micro-crack systems; adopt the cluster perforation mode, large-scale injection to promote the extension of the main fracture length; the construction pressure ladder is reduced by 5-8MPa, the displacement is reduced by 2-3 cubic meters / minute, and the power consumption of single cubic meter of liquid is reduced, which ensures the transformation effect and saves energy and reduces consumption. At the same time, on the basis of the full-voltage fracturing equipment, an online lubrication system and a fully automatic sand conveying device are equipped to realize the one-button fracturing with centralized remote control of the whole process, meet the needs of long-term continuous injection of large liquid volumes, and compared with the multiple start-stop fracturing of diesel units, the length of the fracture is increased by 8-9%, which greatly improves the construction time efficiency and reduces the construction cost.

[0021] The following takes a certain area in Jiangsu as an example to verify its effect: The structure of the Fu 2nd section of a shale oil sub-sag in Jiangsu is complex, with large stratum fluctuations and a stratum dip angle of 8.5° to 18°. Taking directional well A as an example, the well inclination angle is 4 to 30 degrees, and the thickness of the Fu 2nd section of the development layer encountered is 451m, of which the thickness of the first and second class high-quality reservoirs is 251m, the gas logging is 52% of total hydrocarbons, the laminations and fractures are well developed, the stress difference coefficient is small, and the brittleness index is high at 65.8%, which is conducive to the formation of a complex fracture network by fracturing transformation. The near-well area is prone to excessive complexity, and it is difficult to expand and extend the fractures and add sand.

[0022] The fracturing method provided by the present invention is used to perform quasi-horizontal well fracturing and verify the effect thereof. The specific steps are as follows: Step 1: Design fracturing process parameters using the basic data of the well; Based on the monitoring of the high fractures in the adjacent wells in the block, the length of the oil test section of the Ⅰ-Ⅱ sub-section is 256m, divided into 4 layers, with an average section length of 64m, 4 clusters of perforations in a single section, and a cluster spacing of 12.8m. Using mature simulation software to simulate the fracturing construction data, the main fracturing process parameters required to achieve the fracture parameters of 255m half-length of the fracturing fluid and 55m fracture height were obtained. The single-section design liquid volume is 12000m³, the sand volume is 500m³, and the displacement is 14-18m³ / min.

[0023] The site is equipped with all-electric equipment, including 6000 electric pumps, electric sand mixing skids, automatic sand conveying devices, and automatic pressure-stabilizing pumping systems. The fracturing wellhead grade is 105MPa, and the fracturing construction pressure limit is 84MPa.

[0024] Step 2: Pump 20m in the first section 3 Acid, the acid delivery rate is 4m³ / min. After the acid enters the formation, the construction pressure drops from 42.07Mpa to 38.19MPa. In the remaining fracturing stages, the amount of acid pumped can be adjusted according to the pumping pressure of each layer. Step 3: Inject low-viscosity fracturing fluid, quickly increase the displacement to 14m³ / min, and the fracture pressure is 82.2MPa. After fracture, increase the displacement to 17.85m³ / min and inject pre-fracturing fluid; Step 4: In the first stage of fracturing, the pressure window is controlled at 4MPa, and the construction pressure reference value is 80MPa; the automatic pressure-stabilizing pumping system is put into use, the fluctuation range is set to ±0.5MPa, and the construction displacement of the electric pump is adjusted in steps, and the displacement step adjustment range is 0.1m³ / min; A. Pump in 300m3 of low-viscosity fracturing fluid with a concentration of 0.1% 3 ; b. Pump in 0.12% low-viscosity fracturing fluid with 100 / 200 mesh proppant, and continuously add 100m³ of 100 / 200 mesh proppant to fill the support layer fractures and micro-cracks; at the same time, add 0.1% oil washing agent (600m³ of fracturing fluid for slug interval) in slug injection; c. Pump in medium viscosity fracturing fluid with a concentration of 0.15% and 70 / 140 mesh proppant, and continuously add 90m³ of 70 / 140 mesh proppant to fill the branch fractures; D. Pumping in a total of 4090m³ of fracturing fluid and 190m³ of sand, completing the first phase of construction; In the second stage of fracturing, the pressure window is controlled at 11MPa, the pumping rate is reduced to 15.65m³ / min, and the construction pressure reference value is 73MPa; relying on the automatic pressure-stabilizing pumping system, the pressure fluctuation range is ±0.5MPa; a. Pump in medium viscosity fracturing fluid with a concentration of 0.18% and 70 / 140 mesh proppant, and continuously add 60m³ of 70 / 140 mesh proppant to fill the branch fractures; b. Pump medium-high viscosity fracturing fluid with a concentration of 0.22% and 40 / 70 mesh proppant into the main fracture, and add 90m³ of 40 / 70 mesh proppant to fill the main fracture; D. Pump in a total of 8,100 m³ of fracturing fluid and 350 m³ of sand, completing the second phase of construction; In the third stage of fracturing, the pressure window is controlled at 18MPa, the pumping rate is reduced to 13.62m³ / min, and the construction pressure reference value is 66MPa; relying on the automatic pressure-stabilizing pumping system, the pressure fluctuation range is ±0.5MPa; a. Pump in medium-high viscosity fracturing fluid with a concentration of 0.24% and 40 / 70 mesh quartz sand proppant, and continuously add 140m³ of 40 / 70 mesh proppant to fill the main fractures; b. Pump 0.28% high-viscosity fracturing fluid carrying 40 / 70 mesh ceramsite proppant into the main seam, add 20m³ of 40 / 70 mesh proppant to establish a high-conductivity propped seam at the seam mouth; D. The total fracturing fluid volume of the single layer is 12005.78m³, and the sand volume is 502.29m³, completing the third stage of construction, that is, the single layer construction is completed, and the comprehensive sand-to-liquid ratio of the single layer is 4.18%; Step 5: Follow the above steps to complete the fracturing and sanding of the remaining layers.

[0025] In this embodiment, the main formula of the pretreatment acid is 15% HCl + 2.0% high temperature corrosion inhibitor + 1.5% drainage agent + 2.0% clay stabilizer + 1.5% iron ion stabilizer; In this embodiment, during the fracturing fluid sand-carrying process, a 0.1% oil washing agent is added in a plug-like manner, with a single plug volume of 600 m³ and a spacer fluid volume of 600 m³; the oil washing agent is used to change the wettability of the shale oil reservoir, reduce the oil-water interfacial tension, and improve the crude oil recovery rate; In this embodiment, 100 / 200 mesh quartz sand proppants are selected for shale oil reservoir fracturing to fill the support layer fractures and micro-cracks in the early stage, and 70 / 140 mesh + 40 / 70 mesh low-density expanded clay proppants are selected in the middle and late stages. A multi-size proppant and sand addition method is adopted, and the three-dimensional fracture network at each level is effectively supported, the fracture conductivity is enhanced, and the output of shale oil directional wells after fracturing is effectively increased.

[0026] In this embodiment, the main formula of the fracturing fluid is water + 0.1-0.28% drag reducer + 0.1% composite anti-swelling agent + 0.02% bactericide, wherein the drag reducer dosage is prepared in a proportion according to the technical solution, generally in a linear proportion. The variability of the viscosity of the fracturing fluid improves the sand carrying capacity of the fracturing fluid.

[0027] After verification, the fracturing method of the present invention was used to implement fracturing reconstruction construction on Well A. Well A completed a total of 4 stages of fracturing construction, with a total amount of liquid injected into the formation of 48023m3 , cumulative sand added 2009m 3 The average amount of sand added per meter is 8.55m³ / m, and the comprehensive sand-liquid ratio of a single well is 4.18%. The fracture network monitoring data shows that the half-fracture length and transformation volume of the fracture have increased to 1.6 and 1.76 times that of the horizontal well, effectively increasing the fracture control reserves. After the 4mm oil nozzle test, the maximum daily oil production reached 64.5m³ / d, achieving a major breakthrough in production, creating a new mode of directional fracturing for shale oil, and leading the efficient use of fault block shale oil in complex structural areas.

[0028] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A shale oil directional well quasi-horizontal well fracturing process, characterized in that: The following steps are involved: S1: Based on the geological and engineering data of the fault-block shale reservoir and the fracture parameters of the previous fracturing wells in the block, the three-dimensional stratification and clustering of directional wells and the main fracturing process parameters are determined; S2: injecting acid into the reservoir in large volume for acid pretreatment; S3: Switch to low-viscosity fracturing fluid injection and quickly increase the displacement; S4: The reverse design focuses on different operation pressure windows, adopts a three-stage operation pressure control and displacement adjustment mode to stabilize pressure and add sand, and completes single-layer fracturing and adding sand; S5: Follow the above steps to complete the fracturing and sanding of the remaining layers of the single well.

2. The shale oil directional well pseudo-horizontal well fracturing process according to claim 1 is characterized in that: In step S1, the three-dimensional stratification and clustering parameters of the directional wells are determined based on the existing reservoir physical properties and engineering parameters of the fault block area and combined with the fracture height data monitored by the fractured wells.

3. The shale oil directional well pseudo-horizontal well fracturing process according to claim 1 or 2 is characterized in that: In step S1, the directional well preferably has 3-4 clusters of perforations in a single layer.

4. The shale oil directional well pseudo-horizontal well fracturing process according to claim 1 is characterized in that: In step S2, the amount of acid used per layer is 20-30m 3 , pumping capacity 3-5m 3 / min.

5. The shale oil directional well pseudo-horizontal well fracturing process according to claim 1 is characterized in that: The acid solution in step S2 includes hydrochloric acid, a high-temperature corrosion inhibitor, a drainage aid, a clay stabilizer, and an iron ion stabilizer.

6. The shale oil directional well pseudo-horizontal well fracturing process according to claim 1 or 2 is characterized in that: In step S3, the injection of low-viscosity fracturing fluid is switched to increase the displacement under the construction pressure limit to form a high fracture pressure.

7. The shale oil directional well pseudo-horizontal well fracturing process according to claim 1 is characterized in that: In the step S4, Phase 1 Mode: Adjust the pump injection and displacement to control the pressure window at 4-5MPa; a. Pump low-viscosity fracturing fluid to carry small-particle proppant to fill micro-cracks, with a sand-to-liquid ratio of 2%-10%. Simultaneously, add a low-concentration 0.1% synergist through slug injection to complete the addition of small-particle proppant; b. Pump in medium-viscosity fracturing fluid carrying medium-sized proppant to fill branch fractures, with a sand-to-fluid ratio of 2%-10%; c. During the pumping process, the automatic pressure-stabilizing pumping system is activated and the pressure fluctuation amplitude is set. When the pressure fluctuation reaches the upper and lower limits, the step adjustment of the displacement is triggered to maintain a stable pressure. d. Complete 1 / 3 of the total liquid volume; Second stage mode: Adjust the pump injection volume, reduce the construction pressure, and control the pressure window to 10-14MPa; a. Pump in medium-viscosity fracturing fluid carrying medium-sized proppant to fill micro-fractures, with a sand-to-liquid ratio of 7%-10%; b. Pump medium-high viscosity fracturing fluid carrying medium-large particle proppant to fill the main fracture, with a sand-to-fluid ratio of 2%-5%; c. During the pumping process, the automatic pressure-stabilizing pumping system is activated and the pressure fluctuation amplitude is set. When the pressure fluctuation reaches the upper and lower limits, the step adjustment of the displacement is triggered to maintain a stable pressure. d. Complete 2 / 3 of the total liquid volume; Phase 3 Mode: Adjust the pump injection volume, reduce the construction pressure, and control the pressure window to 17-20MPa; a. Pump medium-high viscosity fracturing fluid carrying medium-sized proppant to fill the main fracture, with a sand-to-fluid ratio of 4%-5%; b. Pump high-viscosity fracturing fluid and tail-follow ceramsite proppant to establish a high-conductivity channel at the fracture mouth, with a sand-to-liquid ratio of 4%-5%; c. During the pumping process, the automatic pressure-stabilizing pumping system is activated and the pressure fluctuation amplitude is set. When the pressure fluctuation reaches the upper and lower limits, the step adjustment of the displacement is triggered to maintain a stable pressure. d. Complete the single-layer sand and liquid volume, with a comprehensive sand-liquid ratio of 3.0%-4.5%.

8. The shale oil directional well pseudo-horizontal well fracturing process according to claim 7 is characterized in that: The proppant in step S4 is a multi-grade particle size proppant, including 100 / 200 mesh proppant, 70 / 140 mesh proppant, 40 / 70 mesh proppant, 30 / 50 mesh or a larger particle size 20 / 40 mesh proppant.

9. The shale oil directional well pseudo-horizontal well fracturing process according to claim 7 is characterized in that: The proportion of proppants of different particle sizes is as follows: the volume of small particle size proppant: the volume of medium particle size proppant: the volume of large particle size proppant = 2:3:

5.

10. The shale oil directional well quasi-horizontal well fracturing process according to claim 7 is characterized in that: The low-viscosity fracturing fluid is a drag reducer with a concentration of 0.08-0.12%; the medium-viscosity fracturing fluid is a drag reducer with a concentration of 0.13-0.18%; the medium-high-viscosity fracturing fluid is a drag reducer with a concentration of 0.19-0.24%; and the high-viscosity fracturing fluid is a drag reducer with a concentration of 0.25-0.30%.

Images