Fracturing transformation method for multi-process combination to avoid water injection layer series

Abstract

The invention discloses a multi-process combined fracturing transformation method for avoiding a water injection layer series, which comprises the following specific steps of: 1, comprehensively logging and logging to explain the condition of an oil-water layer and the characteristics of fracturing transformation, classifying and grading a horizontal section, and determining an engineering dessert; 2, differentiated cloth seam design is carried out according to the engineering dessert distribution in the step 1; step 3, determining design parameters of the horizontal well according to the position of the engineering dessert of the horizontal section and the seam distribution mode; 4, different types of perforation technologies are selected according to the design parameters in the step 3; 5, fracturing operation is conducted according to the perforation technology determined in the step 4; and step 6, monitoring the fracturing operation process in real time by adopting underground microseism, adjusting design parameters, and guiding fracturing construction. According to the fracturing transformation method for avoiding the water injection layer series through the multi-process combination, the design parameters of the horizontal well are adjusted, different perforation technologies are selected for fracturing operation, and communication of the water injection development layer series or the water drive front edge is effectively avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of oil well mining, and specifically relates to a fracturing reconstruction method for avoiding water injection strata series by multi-process combination. Background Technique

[0002] With the increasing exploration and development efforts, shale oil reservoirs with large resource reserves have become important replacement reserves, and most of these shale oil reservoirs are located between two sets of water injection development horizons. The evaluation test of the water drive front shows that almost more than 90% of the horizontal sections overlap with the water drive fronts of the upper and lower development wells. However, the vertical water drive height is between 15 and 31 m. Traditional methods are often prone to communicate with the water drive front and are prone to water flooding. Therefore, finding a fracturing reconstruction method that can improve the avoidance of water injection strata series has always been a difficult point in the field of oilfield exploration and development.

[0003] Currently, some optimization methods have been proposed, such as limited-entry perforating fracturing, variable sequence fracturing, temporary plugging fracturing, variable viscosity fracturing, etc. However, their effects are often not satisfactory, the production increase is relatively limited, and most wells are flooded. Summary of the Invention

[0004] The purpose of the present invention is to provide a fracturing reconstruction method for avoiding water injection strata series by multi-process combination, so as not to communicate with the water injection development strata series or the water drive front.

[0005] The technical solution adopted by the present invention is a fracturing reconstruction method for avoiding water injection strata series by multi-process combination, which is specifically implemented according to the following steps:

[0006] Step 1: Comprehensively measure and log the interpretation of oil and water layers and the characteristics of fracturing reconstruction, classify and grade the horizontal section, and determine the engineering sweet spots;

[0007] Step 2: Carry out differential slotting design according to the distribution of engineering sweet spots in Step 1;

[0008] Step 3: Determine the design parameters of the horizontal well according to the position of the engineering sweet spot in the horizontal section and the slotting method;

[0009] Step 4: Select different types of perforating technologies according to the design parameters in Step 3;

[0010] Step 5: Carry out fracturing operations according to the perforating technology determined in Step 4;

[0011] Step 6: Use downhole microseismic to monitor the fracturing operation process in real time, adjust the design parameters, and guide the fracturing construction.

[0012] The characteristics of the present invention also lie in:

[0013] In Step 1, the horizontal section is divided into three categories: Category I, Category II, and Category III. Category I is the oil layer, Category II is the poor oil layer or the oil-water coexistence layer, and Category III is the dry layer or the oil-bearing water layer. Category I and Category II are the determined engineering sweet spots.

[0014] In Step 2, the differential fracture layout design is carried out in combination with the thickness of the interlayer between the water injection development layer series and the horizontal section, and is designed according to the distance between the water drive front of the injection well and the horizontal section.

[0015] If the thickness of the interlayer between the water injection development layer series and the horizontal section is greater than 10 m and the distance between the water drive front of the injection well and the horizontal section is greater than 100 m, then the design is carried out according to the dense fracture layout, increasing the transformation scale and the transformation volume; if the thickness of the interlayer between the water injection development layer series and the horizontal section is less than 10 m and the distance between the water drive front of the injection well and the horizontal section is less than 100 m, then the design is carried out according to the single-section fracture layout, controlling the transformation scale and avoiding excessive extension of the longitudinal fracture.

[0016] In Step 3, the design parameters are the number of well sections, the designed fracture length, the sand addition amount per single section, the liquid injection amount per single section into the formation, and the displacement per single section.

[0017] The number of well sections is segmented successively from the bottom of the well for the engineering sweet spots determined in Step 1, divided into the first section, the second section, …, the Nth section, where N is not greater than 60, and the interval between every two well sections is 30 m to 50 m.

[0018] If the thickness of the interlayer between the water injection development layer series and the horizontal section is greater than 10 m and the distance between the water drive front of the injection well and the horizontal section is greater than 100 m, then the designed fracture length is 160 m to 200 m, the sand addition amount per single section is increased by 100 m³ to 200 m³, the liquid injection amount per single section into the formation is 1000 m³ to 2000 m³, and the displacement per single section is 6 m³ / min to 12 m³ / min.

[0019] If the thickness of the interlayer between the water injection development layer series and the horizontal section is less than 10 m and the distance between the water drive front of the injection well and the horizontal section is less than 100 m, then the designed fracture length is 120 m to 150 m, the sand addition amount per single section is increased by 20 m³ to 50 m³, the liquid injection amount per single section into the formation is 200 m³ to 500 m³, and the displacement per single section is 2 m³ / min to 4 m³ / min.

[0020] In Step 4, the perforation technology is fixed-face perforation, bridge-perforation combined operation perforation, or hydraulic jet perforation.

[0021] The first section of the well section uses fixed-face perforation; the perforation technology for the second section to the Nth section is selected according to the thickness of the interlayer between the water injection development layer system and the horizontal section, and the distance between the water drive front of the water injection well and the horizontal section: if the thickness of the interlayer between the water injection development layer system and the horizontal section is greater than 10m and the distance between the water drive front of the water injection well and the horizontal section is greater than 100m, bridge and jet combined perforation is used; if the thickness of the interlayer between the water injection development layer system and the horizontal section is less than 10m and the distance between the water drive front of the water injection well and the horizontal section is less than 100m, hydraulic jet perforation is used.

[0022] The fracturing operation in step 5 is determined according to the oil saturation of the reservoir. When the oil saturation is less than 20%, a fracturing fluid with an additive combination with dialysis function is selected for reservoir fracturing operation; when the oil saturation is greater than 20%, a guar gum fracturing fluid system is selected for reservoir fracturing operation.

[0023] During the fracturing operation in step 6, if it is monitored that the crack extension is 30m - 50m away from the water drive front, reduce the sand addition amount per section by 5% - 20%, reduce the displacement per section by 3% - 20%, and reduce the liquid volume entering the ground per section by 5% - 20%.

[0024] The beneficial effects of the present invention are: The multi-process combination method for avoiding the fracturing transformation of the water injection layer system adjusts the design parameters of the horizontal well by combining the thickness of the interlayer between the water injection development layer system and the horizontal section and the distance between the water drive front of the water injection well and the horizontal section, selects different perforation technologies for fracturing operations, and guides the fracturing construction, effectively avoiding the communication of the water injection development layer system or the water drive front, which is of great significance for improving the shale oil extraction efficiency. Brief Description of the Drawings

[0025] Figure 1 is the flow chart of the fracturing transformation method of the present invention; Detailed Embodiments

[0026] The present invention will be described in detail below in conjunction with the drawings and specific embodiments.

[0027] The fracturing transformation method for avoiding the water injection layer system by multi-process combination, as Figure 1 shown, is specifically implemented according to the following steps:

[0028] Step 1: Comprehensively measure and log to interpret the oil and water layer conditions and the characteristics of fracturing transformation, classify and grade the horizontal section, and determine the engineering sweet spots; First, the horizontal section is divided into three categories: I, II, and III. Among them, category I is the oil layer, the main contributing section; category II is the poor oil layer or the oil-water coexisting layer, the secondary contributing layer, and category III is the dry layer or the oil-bearing water layer, with the risk of ineffective or water production during fracturing transformation, which needs to be carefully considered. Among them, categories I and II are the key points of transformation, that is, the preferred engineering sweet spots.

[0029] Step 2: Conduct differential joint design based on the engineering sweet spot distribution in Step 1. Among them, the differential joint design is carried out in combination with the thickness of the interlayer between the water injection development layer system and the horizontal section, and the distance between the water drive front of the injection well and the horizontal section.

[0030] If the thickness of the interlayer between the water injection development layer system and the horizontal section is greater than 10m and the distance between the water drive front of the injection well and the horizontal section is greater than 100m, then design according to dense joint arrangement, increasing the transformation scale and increasing the transformation volume.

[0031] If the thickness of the interlayer between the water injection development layer system and the horizontal section is less than 10m and the distance between the water drive front of the injection well and the horizontal section is less than 100m, then design according to single-section joint arrangement, controlling the transformation scale to avoid excessive extension of longitudinal cracks.

[0032] Step 3: Determine the design parameters of the horizontal well according to the engineering sweet spot position and joint arrangement method of the horizontal section, including the number of well sections, designed joint length, sand addition volume per section, liquid volume entering the ground per section, and displacement per section.

[0033] Among them, the number of well sections is segmented successively from the bottom of the well for the engineering sweet spots determined in Step 1, divided into the first section, the second section,....... the Nth section, where N is not greater than 60, and the interval between every two well sections is 30m - 50m; the designed joint length is the designed crack length, which cannot communicate with the water injection development layer system and the water drive front of the injection well; the liquid volume entering the ground per section is the total liquid volume entering the ground for each section; the displacement per section is the maximum pumping volume per minute for each section.

[0034] If the thickness of the interlayer between the water injection development layer system and the horizontal section is greater than 10m and the distance between the water drive front of the injection well and the horizontal section is greater than 100m, then the designed joint length is 160m - 200m, increasing the sand addition volume per section by 100 m³ - 200 m³, the liquid volume entering the ground per section by 1000 m³ - 2000 m³, and the displacement per section by 6 m³ / min - 12 m³ / min;

[0035] If the thickness of the interlayer between the water injection development layer system and the horizontal section is less than 10m and the distance between the water drive front of the injection well and the horizontal section is less than 100m, then the designed joint length is 120m - 150m, increasing the sand addition volume per section by 20 m³ - 50 m³, the liquid volume entering the ground per section by 200 m³ - 500 m³, and the displacement per section by 2 m³ / min - 4 m³ / min.

[0036] Step 4: Select different types of perforation technologies based on the design parameters in Step 3. Among them, the perforation technology is fixed-face perforation, bridge-perforation combined operation perforation or hydraulic jet perforation.

[0037] In order to initiate cracking evenly in the first section, fixed-surface perforation is adopted; the perforation technology of the second to Nth sections is selected according to the thickness of the interlayer between the water injection development layer and the horizontal section, and the distance between the water drive front edge of the water injection well and the horizontal section: when the thickness of the interlayer between the water injection development layer and the horizontal section is greater than 10m, and the distance between the water drive front edge of the water injection well and the horizontal section is greater than 100m, bridge perforation is adopted; when the thickness of the interlayer between the water injection development layer and the horizontal section is less than 10m, and the distance between the water drive front edge of the water injection well and the horizontal section is less than 100m, hydraulic sandblasting perforation is adopted.

[0038] Step 5: On the basis of implementing the perforation technology, perform fracturing operations; according to the perforation technology determined in step 4, determine according to the oil saturation of the reservoir. When the oil saturation is less than 20%, select a fracturing fluid with a combination of additives with a dialysis function to perform reservoir fracturing operations. The fracturing fluid is an existing technology, and the commonly used fracturing fluid mainly contains 0.06% to 1.0% drag reducer, 0.06% to 1.0% nanoemulsion, and 0.8% to 1.2% clay stabilizer; when the oil saturation is greater than 20%, select a guar gum fracturing fluid system to perform reservoir fracturing operations. The fracturing fluid is an existing technology, and the commonly used fracturing fluid mainly contains 0.15% to 0.35% drag reducer, 0.3% to 0.7% clay stabilizer, 0.15% to 0.35% drainage aid, and 0.15% to 0.55% hydroxypropyl guar gum.

[0039] Step 6: Use downhole microseismic to monitor the fracturing process in real time, adjust the design parameters, guide the fracturing construction, and achieve well section fracturing, production increase and transformation. During the fracturing operation, use downhole microseismic to adjust the construction parameters in time according to the extension of the cracks to avoid cross-fracturing or communication with the water drive front.

[0040] Downhole microseismicity mainly monitors the extension of fractures. According to the extension of fractures, the three parameters of single-stage sand addition, single-stage ground liquid volume, and single-stage displacement in step 3 are adjusted. The fracture extension cannot be greater than the designed fracture length. If the monitoring finds that the fracture extension is 30m to 50m away from the water drive front, the single-stage sand addition amount is reduced by 5% to 20%, the single-stage displacement is reduced by 3% to 20%, and the single-stage ground liquid volume is reduced by 5% to 20%. The fracture height cannot be greater than the thickness of the interlayer between the water injection development layer and the horizontal section.

[0041] Example 1

[0042] Taking Well S1H as an example, the multi-process combination fracturing transformation method to avoid the water injection layer system is implemented in the following steps:

[0043] Step 1: According to the logging and mud logging interpretation of oil and water layers and the characteristics of fracturing transformation, the horizontal section is divided into three categories: I, II, and III. Among them, Category I is the oil layer with a thickness of 994.8 m, which is the main contributing section; Category II is the poor oil layer or oil-water layer with a thickness of 719.8 m, which is the secondary contributing layer; Category III is the dry layer or oil-bearing water layer with a thickness of 285.4 m. There is a risk of ineffective fracturing transformation or water production, which needs to be carefully considered. Categories I and II are the engineering sweet spots.

[0044] Step 2: Based on the engineering sweet spots determined in Step 1, combined with the thickness of the interlayer between the upper and lower water injection development strata and the horizontal section, and the distance between the water drive front of the injection well and the horizontal section, a differential fracture layout design is carried out. The entire horizontal section of Well S1H is divided into 39 segments: Among them, for the 1st to 23rd segments, the thickness of the interlayer between the injection development strata is less than 10 m, and the distance between the water drive front of the injection well is less than 100 m. Single-segment fracture layout is adopted, and small-scale hydraulic sandblasting perforation and staged fracturing are used to control the transformation scale and avoid excessive extension of longitudinal fractures; for the 24th to 39th segments, the thickness of the interlayer between the injection development strata is greater than 10 m, and the distance between the water drive front of the injection well is more than 100 m. Dense fracture layout is designed, and bridge-perforation combined with volumetric fracturing is used to increase the transformation scale.

[0045] Step 3: According to the sweet spot position and fracture layout method of the horizontal section, it is determined that Well S1H is transformed into 39 segments and 88 clusters in total. Fracpro software is used for fracture simulation. Among them, for the 1st to 23rd segments, the designed fracture length is 120 m to 150 m, the liquid volume injected into the ground per single segment is 200 m³ to 500 m³, the sand addition volume per single segment is 20 m³ to 50 m³, and the displacement per single segment is 2 m³ / min to 4 m³ / min; for the 24th to 39th segments, the designed fracture length is 160 m to 200 m, the liquid volume injected into the ground per single segment is 1000 m³ to 2000 m³, the sand addition volume per single segment is 100 m³ to 200 m³, and the displacement per single segment is 6 m³ / min to 12 m³ / min.

[0046] Step 4: Based on the design parameters in Step 3, fixed-face perforation, hydraulic sandblasting perforation, and bridge-perforation combined are selected. Among them, for the first segment, fixed-face perforation is used to achieve uniform fracture initiation; for the 2nd to 23rd segments, since they are close to the injection development strata and the water drive front of the injection well, hydraulic sandblasting perforation is used; for the 24th to 39th segments, since the distance from the injection development strata and the water drive front of the injection well is more than 100 m, bridge-perforation combined is used for perforation.

[0047] Step 5: According to the perforation technology determined in Step 4, fracturing operations are carried out. Among them, the fracturing operation is determined according to the oil saturation of the reservoir. Since the overall oil content of Well S1H is less than 20%, CNI fracturing fluid with dialysis function is used for fracturing operations in this well. The main components of the fracturing fluid are drag reducer 0.08%, nano-emulsion 0.08%, and clay stabilizer 1.0%.

[0048] Step 6: Use downhole microseismic to monitor the fracturing operation in real time. During the fracturing operation of the 36th stage, downhole microseismic monitoring showed that the fracture extension was 50 m away from the water drive front. To avoid communicating with the water drive front, the design parameters were adjusted in a timely manner. The designed single-stage displacement was 10 m³ / min, the single-stage liquid volume injected into the ground was 1386 m³, and the single-stage sand addition volume was 190 m³. During the construction process, the single-stage displacement was reduced from 10 m³ / min to 8 m³ / min, the single-stage liquid volume injected into the ground was reduced from 1386 m³ to 1174 m³, and the single-stage sand addition volume was reduced from 190 m³ to 159 m³.

[0049] Example 2

[0050] A fracturing transformation method using a multi-process combination to avoid the water injection layer system is specifically implemented according to the following steps:

[0051] Step 1: Comprehensively log and interpret the oil-water layer conditions and fracturing transformation characteristics, classify and grade the horizontal section, and determine the engineering sweet spots. The horizontal section is divided into three categories: Category I, Category II, and Category III. Among them, Category I is the oil layer, the main contributing section; Category II is the poor oil layer or the oil-water coexisting layer, the secondary contributing layer; Category III is the dry layer or the oil-bearing water layer, and there is a risk of ineffective fracturing transformation or water production, which needs to be carefully considered. Among them, Category I and Category II are the key points of transformation, that is, the preferred engineering sweet spots.

[0052] Step 2: Conduct a differential slot layout design according to the distribution of the engineering sweet spots in Step 1. Among them, the differential slot layout design is carried out in combination with the thickness of the interlayer between the water injection development layer system and the horizontal section and the distance between the water drive front of the injection well and the horizontal section.

[0053] When the thickness of the interlayer between the water injection development layer system and the horizontal section is 11 m and the distance between the water drive front of the injection well and the horizontal section is 110 m, the design is carried out according to dense slot layout, increasing the transformation scale, and increasing the transformation volume.

[0054] Step 3: Determine the design parameters of the horizontal well according to the position of the engineering sweet spots in the horizontal section and the slot layout method, including the number of well sections, the designed slot length, the single-stage sand addition volume, the single-stage liquid volume injected into the ground, and the single-stage displacement.

[0055] Since the thickness of the interlayer between the water injection development layer system and the horizontal section is 11 m and the distance between the water drive front of the injection well and the horizontal section is 110 m, the designed slot length is 160 m, the single-stage sand addition volume is increased to 100 m³, the single-stage liquid volume injected into the ground is 1000 m³, and the single-stage displacement is 6 m³ / min.

[0056] Step 4: According to the design parameters in Step 3, use bridge-shot continuous perforation.

[0057] Step 5: Based on the bridge shot and continuous perforation, the oil saturation of the reservoir is determined to be 30%. A guar gum fracturing fluid system is selected to carry out reservoir fracturing operations. The main components of the fracturing fluid are 0.15% drag reducer, 0.3% clay stabilizer, 0.15% drainage aid and 0.15% hydroxypropyl guar gum.

[0058] Step 6: Use downhole microseismic to monitor the fracturing process in real time, adjust the design parameters, guide the fracturing construction, and achieve well section fracturing, production increase and transformation. During the fracturing operation, use downhole microseismic to adjust the construction parameters in time according to the extension of the cracks to avoid cross-fracturing or communication with the water drive front.

[0059] Downhole microseismicity mainly monitors the extension of fractures. When the monitoring finds that the fracture extension is 30m away from the water drive front, the amount of sand added is reduced by 20%, the single-stage displacement is reduced by 20%, and the single-stage in-ground fluid is reduced by 20%. The fracture height cannot be greater than the thickness of the interlayer between the water injection development layer and the horizontal section.

[0060] Example 3

[0061] The multi-process combination fracturing transformation method to avoid water injection layer system is implemented in the following steps:

[0062] Step 1: Comprehensive logging and mud recording to interpret the oil-water layer conditions and the characteristics of fracturing transformation, classify and grade the horizontal sections, and determine the engineering sweet spots; the horizontal sections are divided into I, II, and III categories, among which Class I is the oil layer, the main contribution section; Class II is the poor oil layer or the oil-water layer, the secondary contribution layer, and Class III is the dry layer or the oil-water layer. Fracturing transformation has the risk of ineffectiveness or water production, and needs to be carefully considered. Among them, Class I and Class II are the focus of transformation, that is, the preferred engineering sweet spots.

[0063] Step 2: Perform differentiated seam layout design according to the engineering sweet spot distribution in step 1; wherein the differentiated seam layout design is designed in combination with the thickness of the interlayer between the water injection development layer system and the horizontal section, and the distance between the water injection well water drive front and the horizontal section;

[0064] When the thickness of the interlayer between the water injection development layer and the horizontal section is 20m, and the distance between the water drive front edge of the water injection well and the horizontal section is 200m, the design is carried out according to dense seam arrangement, increased transformation scale, and increased transformation volume.

[0065] Step 3: According to the sweet spot position and seam layout method of the horizontal section project, determine the design parameters of the horizontal well, including the number of well sections, the designed seam length, the amount of sand added in a single section, the amount of liquid injected into the ground in a single section, and the displacement of a single section;

[0066] Since the thickness of the interlayer between the water injection development layer and the horizontal section is 20m, the distance between the water drive front edge of the water injection well and the horizontal section is 200m, the designed seam length is 200m, the single-stage sand addition volume is increased to 200 cubic meters, the single-stage liquid injection volume is increased to 2000 cubic meters, and the single-stage discharge volume is 12 cubic meters / minute.

[0067] Step 4: Based on the design parameters of step 3, bridge shooting is used for continuous perforation.

[0068] Step 5: Based on the bridge shot and continuous perforation, the oil saturation of the reservoir is determined to be 50%. A guar gum fracturing fluid system is selected to carry out reservoir fracturing operations. The main components of the fracturing fluid are 0.35% drag reducer, 0.7% clay stabilizer, 0.35% drainage aid and 0.55% hydroxypropyl guar gum.

[0069] Step 6: Use downhole microseismic to monitor the fracturing process in real time, adjust the design parameters, guide the fracturing construction, and achieve well section fracturing, production increase and transformation. During the fracturing operation, use downhole microseismic to adjust the construction parameters in time according to the extension of the cracks to avoid cross-fracturing or communication with the water drive front.

[0070] Downhole microseismicity mainly monitors the extension of fractures. When the monitoring finds that the fracture extension is 40m away from the water drive front, the amount of sand added is reduced by 10%, the single-stage displacement is reduced by 15%, and the single-stage in-ground fluid is reduced by 20%. The fracture height cannot be greater than the thickness of the interlayer between the water injection development layer and the horizontal section.

[0071] Example 4

[0072] The multi-process combination fracturing transformation method to avoid water injection layer system is implemented in the following steps:

[0073] Step 1: Comprehensive logging and mud recording to interpret the oil-water layer conditions and the characteristics of fracturing transformation, classify and grade the horizontal sections, and determine the engineering sweet spots; the horizontal sections are divided into I, II, and III categories, among which Class I is the oil layer, the main contribution section; Class II is the poor oil layer or the oil-water layer, the secondary contribution layer, and Class III is the dry layer or the oil-water layer. Fracturing transformation has the risk of ineffectiveness or water production, and needs to be carefully considered. Among them, Class I and Class II are the focus of transformation, that is, the preferred engineering sweet spots.

[0074] Step 2: Perform differentiated seam layout design according to the engineering sweet spot distribution in step 1; wherein the differentiated seam layout design is designed in combination with the thickness of the interlayer between the water injection development layer system and the horizontal section, and the distance between the water injection well water drive front and the horizontal section;

[0075] When the thickness of the interlayer between the water injection development layer and the horizontal section is 9m, and the distance between the water drive front edge of the water injection well and the horizontal section is 90m, the seams are arranged in a single section to control the scale of transformation and avoid excessive extension of longitudinal cracks.

[0076] Step 3: Determine the design parameters of the horizontal well according to the engineering sweet spot position and the seam layout method in the horizontal section, including the number of well sections, the designed seam length, the liquid volume injected into the ground per single section, the displacement per single section, and the sand addition amount per single section;

[0077] If the thickness of the interlayer between the water injection development layer series and the horizontal section is 9 m, and the distance between the water drive front of the injection well and the horizontal section is 90 m, then the designed seam length is 150 m, the sand addition amount per single section is increased by 50 m³, the liquid volume injected into the ground per single section is 500 m³, and the displacement per single section is 4 m³ / min.

[0078] Step 4: Carry out hydraulic sandblasting perforation according to the design parameters in Step 3.

[0079] Step 5: On the basis of hydraulic sandblasting perforation, determine according to the oil saturation of the reservoir. When the oil saturation is 10%, select a fracturing fluid with an additive combination having a dialysis function to perform reservoir fracturing operation. The main components of the fracturing fluid are 1.0% drag reducer, 1.0% nanoemulsion, and 1.2% clay stabilizer.

[0080] Step 6: Use downhole microseismic to monitor the fracturing operation process in real time, adjust the design parameters, guide the fracturing construction, and achieve well section fracturing, production increase, and transformation. During the fracturing operation, support with downhole microseismic, and according to the fracture extension situation, timely adjust the construction parameters to avoid fracturing into adjacent wells or communicating with the water drive front.

[0081] The downhole microseismic mainly monitors the fracture extension situation. When it is monitored that the interval between the fracture extension and the water drive front is 45 m, reduce the sand addition amount by 15%, reduce the displacement per single section by 10%, and reduce the liquid volume injected into the ground per single section by 10%. The fracture height cannot be greater than the thickness of the interlayer between the water injection development layer series and the horizontal section.

Claims

1. A fracturing and reforming method for multi-process combination to avoid water injection formations, characterized in that The implementation is specifically carried out according to the following steps: Step 1: Classify and grade the horizontal section by comprehensively considering the logging and mud logging interpretations of oil and water layers and the characteristics of fracturing transformation, and determine the engineering sweet spots; Step 2: Conduct differential fracture layout design based on the distribution of engineering sweet spots in Step 1; Step 3: Determine the design parameters of the horizontal well according to the position of the engineering sweet spots in the horizontal section and the fracture layout method; Step 4: Select different types of perforation technologies based on the design parameters in Step 3; Step 5: Conduct fracturing operations according to the perforation technology determined in Step 4; Step 6: Use downhole microseismic to monitor the fracturing operation process in real time, adjust the design parameters, and guide the fracturing construction.

2. The fracturing transformation method for avoiding water injection formations by multi-process combination according to claim 1, characterized in that, In Step 1, the horizontal section is divided into Class I, Class II, and Class III. Among them, Class I is the oil layer, Class II is the poor oil layer or oil-water layer, Class III is the dry layer or oil-bearing water layer, and Class I and Class II are the determined engineering sweet spots.

3. The fracturing transformation method for avoiding water injection strata series by multi-process combination according to claim 1, characterized in that The differential fracture layout design in Step 2 is designed by combining the thickness of the interlayer between the water injection development layer series and the horizontal section and according to the distance between the water drive front of the water injection well and the horizontal section.

4. The fracturing reconstruction method for avoiding water injection strata series by multi - process combination according to claim 3, characterized in that, If the thickness of the interlayer between the water injection development layer series and the horizontal section is greater than 10m and the distance between the water drive front of the water injection well and the horizontal section is greater than 100m, then design according to dense fracture layout, increase the transformation scale, and increase the transformation volume; if the thickness of the interlayer between the water injection development layer series and the horizontal section is less than 10m and the distance between the water drive front of the water injection well and the horizontal section is less than 100m, then design according to single-section fracture layout, control the transformation scale, and avoid excessive longitudinal fracture extension.

5. The fracturing reconstruction method for avoiding water injection strata series by multi-process combination according to claim 1, characterized in that, The design parameters in Step 3 are the number of well sections, the designed fracture length, the sand addition amount per section, the liquid injection amount per section into the ground, and the displacement per section.

6. The fracturing reconstruction method for avoiding water injection strata series by multi-process combination according to claim 5, characterized in that The number of well sections is segmented sequentially from the bottom of the well for the engineering sweet spots determined in Step 1, divided into the first section, the second section,......, the Nth section, where N is not greater than 60, and the interval between every two well sections is 30m - 50m; If the thickness of the interlayer between the water injection development layer series and the horizontal section is greater than 10m and the distance between the water drive front of the water injection well and the horizontal section is greater than 100m, then design a fracture length of 160m - 200m, increase the sand addition amount per section by 100 m³ - 200 m³, the liquid injection amount per section into the ground by 1000 m³ - 2000 m³, and the displacement per section by 6 m³ / min - 12 m³ / min; If the thickness of the interlayer between the water injection development layer series and the horizontal section is less than 10m and the distance between the water drive front of the water injection well and the horizontal section is less than 100m, then design a fracture length of 120m - 150m, increase the sand addition amount per section by 20 m³ - 50 m³, the liquid injection amount per section into the ground by 200 m³ - 500 m³, and the displacement per section by 2 m³ / min - 4 m³ / min.

7. The fracturing and reconstruction method for avoiding water injection formations by multi-process combination according to claim 1, characterized in that, The perforation technologies in Step 4 are fixed-face perforation, bridge-perforation combined operation perforation, or hydraulic jet perforation.

8. The fracturing reconstruction method for avoiding water injection strata series by multi-process combination according to claim 7, characterized in that, The first section of the well section uses fixed-face perforation; the perforation technology for the second section to the Nth section is selected according to the thickness of the interlayer between the water injection development layer series and the horizontal section, and the distance between the water drive front of the water injection well and the horizontal section: if the thickness of the interlayer between the water injection development layer series and the horizontal section is greater than 10 m and the distance between the water drive front of the water injection well and the horizontal section is greater than 100 m, bridge-perforating and coiled tubing operation perforation is used; if the thickness of the interlayer between the water injection development layer series and the horizontal section is less than 10 m and the distance between the water drive front of the water injection well and the horizontal section is less than 100 m, hydraulic jet perforation is used.

9. The fracturing reconstruction method for avoiding water injection strata series by multi-process combination according to claim 1, characterized in that, The fracturing operation described in step 5 is determined according to the oil saturation of the reservoir. When the oil saturation is less than 20%, a fracturing fluid with an additive combination having a dialysis function is selected for reservoir fracturing operation; when the oil saturation is greater than 20%, a guar gum fracturing fluid system is selected for reservoir fracturing operation.

10. The fracturing transformation method for avoiding water injection strata by multi - process combination according to claim 1, characterized in that, During the fracturing operation described in step 6, if it is monitored that the crack extension is 30 m to 50 m away from the water drive front, the sand addition amount per single stage is reduced by 5% to 20%, the displacement per single stage is reduced by 3% to 20%, and the liquid volume injected into the ground per single stage is reduced by 5% to 20%.

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