CN113586021A - Horizontal well volume fracturing method and system combining radial well with carbon dioxide fracturing - Google Patents
Horizontal well volume fracturing method and system combining radial well with carbon dioxide fracturing Download PDFInfo
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- CN113586021A CN113586021A CN202010364648.2A CN202010364648A CN113586021A CN 113586021 A CN113586021 A CN 113586021A CN 202010364648 A CN202010364648 A CN 202010364648A CN 113586021 A CN113586021 A CN 113586021A
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- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 200
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 101
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 101
- 238000000034 method Methods 0.000 title claims abstract description 40
- 238000005553 drilling Methods 0.000 claims abstract description 39
- 238000009826 distribution Methods 0.000 claims description 36
- 239000012530 fluid Substances 0.000 claims description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 10
- 239000007788 liquid Substances 0.000 claims description 9
- 230000000694 effects Effects 0.000 abstract description 15
- 238000009792 diffusion process Methods 0.000 abstract description 5
- 238000011084 recovery Methods 0.000 abstract description 5
- 206010017076 Fracture Diseases 0.000 description 29
- 208000010392 Bone Fractures Diseases 0.000 description 20
- 238000010586 diagram Methods 0.000 description 6
- 239000002131 composite material Substances 0.000 description 4
- 238000013461 design Methods 0.000 description 4
- 238000011161 development Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 238000002474 experimental method Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 239000003208 petroleum Substances 0.000 description 3
- 238000004088 simulation Methods 0.000 description 3
- 238000010276 construction Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 239000003915 liquefied petroleum gas Substances 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000011435 rock Substances 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
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- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B43/00—Methods or apparatus for obtaining oil, gas, water, soluble or meltable materials or a slurry of minerals from wells
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
- E21B43/267—Methods for stimulating production by forming crevices or fractures reinforcing fractures by propping
Abstract
The invention discloses a horizontal well volume fracturing method and a horizontal well volume fracturing system combining radial well with carbon dioxide fracturing, wherein the method comprises the following steps: drilling a plurality of radial wells in a horizontal wellbore; performing carbon dioxide fracturing on the radial well; and performing hydraulic fracturing on the radial well subjected to the carbon dioxide fracturing. According to the method, a plurality of radial wells are drilled in a horizontal well, the original ground stress is changed through a radial well stress field formed by the interference among the radial wells during fracturing, the stress in the formed stress field is complex, and when carbon dioxide fracturing is carried out, micro cracks in the radial well stress field are opened by utilizing the characteristics of easiness in diffusion, zero interfacial tension, complex cracks and the like of carbon dioxide to form a primary complex crack network, then hydraulic fracturing is carried out, the micro cracks opened in the carbon dioxide fracturing stage are further expanded to form a supporting crack network, and the effect of volume fracturing is achieved; during hydraulic fracturing, main cracks can be formed at the tail ends of all radial wells, the oil drainage area is further increased due to the form of the main cracks, and the recovery rate is improved.
Description
Technical Field
The invention belongs to the field of petroleum development and production engineering, relates to a fracturing modification technical method, and particularly relates to a horizontal well volume fracturing method combining radial well with carbon dioxide fracturing.
Background
The volume fracturing refers to that in the hydraulic fracturing process, natural fractures are continuously expanded and brittle rocks generate shearing slippage to form a fracture network in which the natural fractures and artificial fractures are staggered, so that the modification volume is increased, and the initial yield and the final recovery rate are improved. The successful construction of volume fracturing has extremely strict requirements on reservoir conditions, such as strong brittleness, natural fracture development, small ground stress difference and the like, and most reservoir layers are difficult to reach the construction standard of volume fracturing, so the popularization and the application of the technology are restricted.
In the invention patent of 'a carbon dioxide-drag reduction water composite fracturing method (CN 201610216886.2)' applied by the tension (2016), a composite method and flow steps of carbon dioxide and hydraulic fracturing are designed, and the effect of enlarging a fracture network and improving the oil and gas productivity is realized by utilizing the performances of different fracturing fluids. In a patent of 'a liquid petroleum gas-carbon dioxide anhydrous energizing composite fracturing method (CN 201610833769.0)' applied by a tension (2016), a reservoir is effectively transformed by sequentially injecting liquid petroleum gas-liquid carbon dioxide sand-carrying liquid-liquid petroleum gas into a stratum, a reticular fracture is formed, the well control area is enlarged, and the stratum energy is increased. In the invention patent "a multi-radial perforation assisted fracturing hole arrangement optimization method (CN 201610875279.7)" applied by song zhangqing (2016), the well arrangement scheme of the radial well is optimized by taking the maximum swept area of the multi-radial well as an evaluation standard, and a plurality of main fractures are formed. In a patent of 'a radial drilling volume fracturing method (CN 201811183054.0)' applied by Liuhua general (2018), based on an interference stress field formed by a radial well, the drilling length and the direction of the radial well are designed for a thin and thick oil reservoir by combining different bottom layer types, the design range of fracturing process parameters is given, and a complex fracture network is formed.
In summary, the volume fracturing technology is limited by the reason that the severe formation conditions are difficult to apply to most reservoirs and difficult to popularize, and although the effectiveness of complex fractures caused by carbon dioxide fracturing is clarified in the prior art, a composite technology for combining the radial well of the horizontal well with the carbon dioxide fracturing is not available.
Disclosure of Invention
The invention aims to provide a horizontal well volume fracturing method and system combining a radial well with carbon dioxide fracturing, and solves the problem that the existing volume fracturing method does not combine the radial well of a horizontal well with the carbon dioxide fracturing.
In order to achieve the above object, the present invention provides a horizontal well volume fracturing method combining radial well with carbon dioxide fracturing, comprising: drilling a plurality of radial wells in a horizontal wellbore; carbon dioxide fracturing the radial well; and performing hydraulic fracturing on the radial well subjected to the carbon dioxide fracturing.
Optionally, drilling a plurality of radial wells in the horizontal wellbore comprises: if the horizontal well is an open hole well completion, radial hydraulic jet flow is carried out at a preset position, and a radial well is drilled; if the horizontal well is completed by the casing, windowing is carried out on the casing at a preset position, radial hydraulic jet flow is carried out on the well wall after the casing is windowed, and a radial well is drilled.
Optionally, the performing of the radial hydraulic jet at the preset position includes: and connecting the hydraulic radial jet flow equipment to the preset position through the coiled tubing, and performing radial hydraulic jet flow through the hydraulic radial jet flow equipment.
Optionally, the performing carbon dioxide fracturing on the radial well comprises: injecting liquid carbon dioxide into the horizontal wellbore by a pump.
Optionally, the hydraulically fracturing the radial well comprises: injecting a water-based fracturing fluid into the horizontal wellbore via a pump.
Optionally, the water-based fracturing fluid is a sand-carrying fracturing fluid.
Optionally, the radial well forms a corresponding radial well stress field during fracturing, and a fitted graph of the radial well stress field distribution range is an ellipse.
Optionally, the well spacing range between the plurality of radial wells is 0.5b < L < b, where L is the well spacing and b is the short axis length of the fitted graph of the radial well stress field distribution range.
In a second aspect, the present invention also provides a horizontal well volume fracturing system combining radial well with carbon dioxide fracturing, the system comprising: a drilling device for drilling a plurality of radial wells in a horizontal wellbore; a first fracturing device for carbon dioxide fracturing the radial well; and the second fracturing device is used for performing hydraulic fracturing on the radial well subjected to carbon dioxide fracturing.
Optionally, the radial well forms a corresponding radial well stress field during fracturing, and a fitted graph of the distribution range of the radial well stress field is an ellipse; the well spacing range between the plurality of radial wells is 0.5b < L < b, wherein L is the well spacing and b is the short axis length of a pattern fitted to the radial well stress field distribution range.
Optionally, drilling a plurality of radial wells in the horizontal wellbore comprises: if the horizontal well is an open hole well completion, radial hydraulic jet flow is carried out at a preset position, and a radial well is drilled; if the horizontal well is completed by the casing, windowing is carried out on the casing at a preset position, radial hydraulic jet flow is carried out on the well wall after the casing is windowed, and a radial well is drilled.
Optionally, the drilling device is a hydraulic radial jet device, and the performing of radial hydraulic jet at the preset position includes: and connecting the hydraulic radial jet flow equipment to the preset position through the coiled tubing, and performing radial hydraulic jet flow through the hydraulic radial jet flow equipment.
The invention has the beneficial effects that: according to the horizontal well volume fracturing method and system combining the radial well with the carbon dioxide fracturing, a plurality of radial wells are drilled in a horizontal well, the fracturing fluid changes the original ground stress through a radial well stress field formed by the interference among the radial wells during fracturing, the stress in the formed stress field is complex, complex cracks are favorably formed, when the carbon dioxide fracturing is carried out, micro cracks in the radial well stress field are opened by utilizing the characteristics of easiness in diffusion, zero interfacial tension, complex cracks and the like of the carbon dioxide, a primary complex crack network is formed, then the hydraulic fracturing is carried out, the micro cracks opened in the carbon dioxide fracturing stage are further expanded and extended, a supporting crack network is formed, the volume fracturing effect is achieved, the application range of the volume fracturing is expanded, and the combination of the radial wells of the horizontal well and the carbon dioxide fracturing is realized; meanwhile, during hydraulic fracturing, main cracks can be formed at the tail ends of all radial wells, the oil drainage area is further increased due to the form of the plurality of main cracks, and the recovery rate is improved.
According to the horizontal well volume fracturing method and system combining the radial well with the carbon dioxide fracturing, disclosed by the invention, through reasonably designing the well spacing between the radial wells, namely optimizing the well distribution scheme, radial well stress field components capable of forming mutual stress interference are formed, a complex seam network is formed in the stress field, and the effect of volume fracturing is achieved.
The present invention has other features and advantages which will be apparent from or are set forth in detail in the accompanying drawings and the following detailed description, which are incorporated herein, and which together serve to explain certain principles of the invention.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.
Figure 1 shows a flow diagram of a horizontal well volume fracturing method with radial well in combination with carbon dioxide fracturing, according to one embodiment of the present invention.
Figure 2 illustrates a cross-sectional view of a plurality of radial wells drilled from a horizontal wellbore of a horizontal well volume fracturing method with radial wells combined with carbon dioxide fracturing, according to one embodiment of the present invention.
Figure 3 shows a fitted graphical representation of the radial well stress field distribution range for a horizontal well volume fracturing method with radial well coupled carbon dioxide fracturing in accordance with an embodiment of the present invention.
FIG. 4 illustrates a radial well coupled carbon dioxide fractured horizontal wellbore multiple radial well stress field distribution schematic in accordance with an embodiment of the present invention.
Figure 5 illustrates a schematic diagram of radial well stress fields and complex fractures within the fields formed after carbon dioxide fracturing for a horizontal well volumetric fracturing method with radial well coupled carbon dioxide fracturing in accordance with an embodiment of the present invention.
Figure 6 illustrates a schematic of a fracture network formed for a horizontal well volume fracturing method with radial well in combination with carbon dioxide fracturing, according to one embodiment of the present invention.
Fig. 7 shows a block diagram of a horizontal well volume fracturing system with radial wells combined with carbon dioxide fracturing, in accordance with an embodiment of the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
The horizontal well volume fracturing method combining the radial well with the carbon dioxide fracturing comprises the following steps: drilling a plurality of radial wells in a horizontal wellbore; performing carbon dioxide fracturing on the radial well; and performing hydraulic fracturing on the radial well subjected to the carbon dioxide fracturing.
Specifically, the radial well is a high-flow-guide channel, so that the seepage resistance can be effectively reduced during production, and the near-well pressure drop is reduced. When the well spacing between two radial wells is smaller than a certain value, the stress fields of the two radial wells are superposed, so that an inter-well interference phenomenon can occur, the original ground stress is changed by the radial well stress field formed by interference, the stress in the formed stress field is complex, and complex cracks are favorably formed.
According to an exemplary embodiment, a plurality of radial wells are drilled in a horizontal well, the fracturing fluid changes the original ground stress through a radial well stress field formed by the interference between the radial wells during fracturing, the stress in the formed stress field is complex, complex cracks are formed, when the carbon dioxide fracturing is performed, micro cracks in the radial well stress field are opened by utilizing the characteristics of easiness in diffusion, zero interfacial tension, complex cracks and the like of the carbon dioxide, a primary complex fracture network is formed, then the hydraulic fracturing is performed, the micro cracks opened in the carbon dioxide fracturing stage are further expanded and extended, a supporting fracture network is formed, the effect of volume fracturing is achieved, and the combination of the radial wells of the horizontal well and the carbon dioxide fracturing is realized; meanwhile, during hydraulic fracturing, main cracks can be formed at the tail ends of all radial wells, the oil drainage area is further increased due to the form of the plurality of main cracks, and the recovery rate is improved.
Alternatively, drilling a plurality of radial wells in a horizontal wellbore comprises: if the horizontal well is an open hole well completion, radial hydraulic jet flow is carried out at a preset position, and a radial well is drilled; if the horizontal well is completed by the casing, windowing is carried out on the casing at a preset position, radial hydraulic jet flow is carried out on the well wall after the casing is windowed, and a radial well is drilled.
Specifically, after the drilling of the horizontal well is finished, if the horizontal well is an open hole completion, radial hydraulic jet flow can be directly carried out; if the horizontal well is completed by the casing, the casing corresponding to the preset drilling position needs to be milled and windowed, and then radial hydraulic jet flow is performed on the well wall after the casing is windowed.
As an alternative, the radial hydraulic jet at the preset position comprises: the hydraulic radial jet flow equipment is connected to a preset position through the coiled tubing, and radial hydraulic jet flow is carried out through the hydraulic radial jet flow equipment.
Specifically, if the horizontal well is an open hole well completion, the coiled tubing is directly connected with a hydraulic radial jet device to enter a preset position of the horizontal shaft, and radial hydraulic jet is performed. If the horizontal well is completed by the casing, the casing corresponding to the preset drilling position needs to be milled and windowed, then the hydraulic radial jet flow equipment connected with the coiled tubing below enters the preset position of the horizontal shaft, and radial hydraulic jet flow is carried out on the well wall after the casing is windowed. After the drilling of the first radial hole is finished, the coiled tubing is lifted according to the design to sequentially drill the subsequent radial boreholes. And after drilling all radial boreholes in the section, replacing the fracturing pipe column to perform fracturing of the section, and after fracturing, putting the bridge plug down to drill the next section of radial boreholes.
Alternatively, carbon dioxide fracturing the radial well comprises: liquid carbon dioxide is injected into the horizontal wellbore by a pump.
Specifically, after high-pressure liquid carbon dioxide is injected into a radial well, a radial well stress field with extremely complex stress distribution can be formed under the interference between radial wells, the distribution of original stress is changed, meanwhile, the carbon dioxide has the characteristics of good diffusivity, zero surface tension and the like, and can easily enter micro cracks and open the micro cracks, so that a complex fracture network mainly formed by opening the micro cracks can be formed in the radial well stress field in the carbon dioxide fracturing stage.
As an alternative, hydraulic fracturing of a radial well comprises: the water-based fracturing fluid is injected into the horizontal wellbore by a pump.
Specifically, after carbon dioxide fracturing, conventional hydraulic fracturing is carried out, so that the microcracks opened in the carbon dioxide fracturing stage are further opened and expanded, an effectively opened fracture network is formed in the multi-radial well stress field range, and the effect of volume fracturing is achieved; further hydraulic fracturing can form new fracture starting point at the tail end of the radial well, and main cracks are gradually formed, at the moment, the homogeneous stratum can form a plurality of main cracks, the oil drainage area is effectively increased, and the development effect is improved.
Alternatively, the water-based fracturing fluid is a sand-carrying fracturing fluid.
Alternatively, the radial well forms a corresponding radial well stress field when fractured, and the fitted graph of the distribution range of the radial well stress field is an ellipse.
Alternatively, the well spacing range between the plurality of radial wells is 0.5b < L < b, where L is the well spacing and b is the minor axis length of the fitted pattern of radial well stress field distribution ranges.
Specifically, each stress field can be equivalent to a geometric figure, such as an ellipse, and the simple geometric figure can achieve the fitting precision of the stress field distribution area of the single radial well. An ellipse is used as a fitting graph of the stress field distribution range of the single radial well, and the change of the ellipse with the length of a long axis and the length of a short axis as b can represent different reservoir parameters and fracture parameters. a. The value of b is determined by experiment or numerical simulation.
The well arrangement scheme of the multi-radial well at the horizontal well section is mainly controlled by the inter-well distance L of the radial well. When the well spacing L is larger than b, the stress fields of the two radial wells are not overlapped or interfered with each other; when the well spacing L is less than b, the stress fields of the two radial wells are superposed, and the inter-well interference phenomenon can occur. The inter-well interference phenomenon of the radial well can cause the inter-well area to form a complex stress field, so that the inter-well area has the condition of forming complex cracks and the effect of volume fracturing. Therefore, when the wells are distributed in a radial direction, the well spacing is smaller than the short axis length of the stress field distribution range fitting image, namely L < b, and meanwhile, the well spacing is not too small, so that the cost is too high, and therefore, 0.5b < L < b is comprehensively considered.
According to an exemplary embodiment, the horizontal well volume fracturing method combining the radial well with the carbon dioxide fracturing forms a radial well stress field component capable of forming mutual stress interference by reasonably designing the well spacing between the radial wells, namely optimizing a well distribution scheme, and forms a complex fracture network in the stress field, so that the volume fracturing effect is achieved.
In a second aspect, a horizontal well volume fracturing system for radial well in combination with carbon dioxide fracturing, in accordance with the present invention, comprises: a drilling device for drilling a plurality of radial wells in a horizontal wellbore; the first fracturing device is used for performing carbon dioxide fracturing on the radial well; and the second fracturing device is used for performing hydraulic fracturing on the radial well subjected to carbon dioxide fracturing.
Specifically, a plurality of radial wells are drilled in the horizontal shaft through the drilling device, the radial wells are high flow guide channels, and seepage resistance and near-well pressure drop can be effectively reduced during production. Each radial wellbore will form a corresponding radial wellbore stress field when the fracturing fluid (which may be water, carbon dioxide or other fracturing fluid) is fractured, when the well distance between two radial wells is less than a certain value, the stress fields of the two radial wells are superposed, so that the inter-well interference phenomenon can occur, the original ground stress can be changed by the radial well stress field formed by interference, the stress in the formed stress field is complex, and the complex cracks can be formed, when carrying out the carbon dioxide fracturing through first fracturing unit, recycle the easy diffusion of carbon dioxide, zero interfacial tension, cause characteristics such as complicated crack to open the micro-crack in the radial well stress field, form preliminary complicated crack net, rethread second fracturing unit carries out hydraulic fracturing, further expands, extends the micro-crack that the carbon dioxide fracturing stage was opened, forms the support crack net, realizes volume fracturing.
According to an exemplary embodiment, a plurality of radial wells are drilled in a horizontal well, a fracturing fluid is used for changing the original ground stress through a radial well stress field formed by interference among the radial wells during fracturing, the stress in the formed stress field is complex, complex cracks are formed, when carbon dioxide fracturing is performed, micro cracks in the radial well stress field are opened by utilizing the characteristics of easiness in diffusion, zero interfacial tension, complex cracks and the like of the carbon dioxide, a primary complex crack network is formed, hydraulic fracturing is performed, the micro cracks opened in a carbon dioxide fracturing stage are further expanded and extended, a supporting crack network is formed, the effect of volume fracturing is achieved, and the combination of the radial wells of the horizontal well and the carbon dioxide fracturing is realized; meanwhile, during hydraulic fracturing, main cracks can be formed at the tail ends of all radial wells, the oil drainage area is further increased due to the form of the plurality of main cracks, and the recovery rate is improved.
As an alternative, the radial well forms a corresponding radial well stress field during fracturing, and a fitted graph of the distribution range of the radial well stress field is an ellipse; the well spacing range between the plurality of radial wells is 0.5b < L < b, wherein L is the well spacing and b is the minor axis length of the fitted graph of the radial well stress field distribution range.
Alternatively, drilling a plurality of radial wells in a horizontal wellbore comprises: if the horizontal well is an open hole well completion, radial hydraulic jet flow is carried out at a preset position, and a radial well is drilled; if the horizontal well is completed by the casing, windowing is carried out on the casing at a preset position, radial hydraulic jet flow is carried out on the well wall after the casing is windowed, and a radial well is drilled.
Specifically, each stress field can be equivalent to a geometric figure, such as an ellipse, and the simple geometric figure can achieve the fitting precision of the stress field distribution area of the single radial well. An ellipse is used as a fitting graph of the stress field distribution range of the single radial well, and the change of the ellipse with the length of a long axis and the length of a short axis as b can represent different reservoir parameters and fracture parameters. a. The value of b is determined by experiment or numerical simulation.
The well arrangement scheme of the multi-radial well at the horizontal well section is mainly controlled by the inter-well distance L of the radial well. When the well spacing L is larger than b, the stress fields of the two radial wells are not overlapped or interfered with each other; when the well spacing L is less than b, the stress fields of the two radial wells are superposed, and the inter-well interference phenomenon can occur. The inter-well interference phenomenon of the radial well can cause the inter-well area to form a complex stress field, so that the inter-well area has the condition of forming complex cracks and the effect of volume fracturing. Therefore, when the wells are distributed in a radial direction, the well spacing is smaller than the short axis length of the stress field distribution range fitting image, namely L < b, and meanwhile, the well spacing is not too small, so that the cost is too high, and therefore, 0.5b < L < b is comprehensively considered.
According to an exemplary embodiment, the horizontal well volume fracturing system combining the radial well with the carbon dioxide fracturing forms a radial well stress field component capable of forming mutual stress interference by reasonably designing the well spacing between the radial wells, namely optimizing a well distribution scheme, and forms a complex fracture network in the stress field, so that the volume fracturing effect is achieved.
Alternatively, the drilling device is a hydraulic radial jet device, and the performing of radial hydraulic jets in preset positions comprises: the hydraulic radial jet flow equipment is connected to a preset position through the coiled tubing, and radial hydraulic jet flow is carried out through the hydraulic radial jet flow equipment.
Specifically, the drilling device is hydraulic radial jet equipment, and the first fracturing device and the second fracturing device are both pumps. If the horizontal well is an open hole well completion, the coiled tubing is directly connected with a hydraulic radial jet device to enter a preset position of the horizontal shaft for radial hydraulic jet. If the horizontal well is completed by the casing, the casing corresponding to the preset drilling position needs to be milled and windowed, then the hydraulic radial jet flow equipment connected with the coiled tubing below enters the preset position of the horizontal shaft, and radial hydraulic jet flow is carried out on the well wall after the casing is windowed. After the drilling of the first radial hole is finished, the coiled tubing is lifted according to the design to sequentially drill the subsequent radial boreholes. And after drilling all radial boreholes in the section, replacing the fracturing pipe column to perform fracturing of the section, and after fracturing, putting the bridge plug down to drill the next section of radial boreholes.
Example one
Figure 1 shows a flow diagram of a horizontal well volume fracturing method with radial well in combination with carbon dioxide fracturing, according to one embodiment of the present invention. Figure 2 illustrates a cross-sectional view of a plurality of radial wells drilled from a horizontal wellbore of a horizontal well volume fracturing method with radial wells combined with carbon dioxide fracturing, according to one embodiment of the present invention. Figure 3 shows a fitted graphical representation of the radial well stress field distribution range for a horizontal well volume fracturing method with radial well coupled carbon dioxide fracturing in accordance with an embodiment of the present invention. FIG. 4 illustrates a radial well coupled carbon dioxide fractured horizontal wellbore multiple radial well stress field distribution schematic in accordance with an embodiment of the present invention. Figure 5 illustrates a schematic diagram of radial well stress fields and complex fractures within the fields formed after carbon dioxide fracturing for a horizontal well volumetric fracturing method with radial well coupled carbon dioxide fracturing in accordance with an embodiment of the present invention. Figure 6 illustrates a schematic of a fracture network formed for a horizontal well volume fracturing method with radial well in combination with carbon dioxide fracturing, according to one embodiment of the present invention.
With reference to fig. 1, 2, 3, 4, 5 and 6, the horizontal well volume fracturing method of a radial well with carbon dioxide fracturing comprises:
s102: drilling a plurality of radial wells in a horizontal wellbore;
wherein drilling a plurality of radial wells in a horizontal wellbore comprises: if the horizontal well is an open hole well completion, radial hydraulic jet flow is carried out at a preset position, and a radial well is drilled; if the horizontal well is completed by the casing, windowing is carried out on the casing at a preset position, radial hydraulic jet flow is carried out on the well wall after the casing is windowed, and a radial well is drilled.
Wherein the radial hydraulic jet at the preset position comprises: the hydraulic radial jet flow equipment is connected to a preset position through the coiled tubing, and radial hydraulic jet flow is carried out through the hydraulic radial jet flow equipment.
Specifically, after the drilling of the horizontal well is finished, if the horizontal well is an open hole completion, radial hydraulic jet flow can be directly carried out; if the horizontal well is completed by the casing, the casing corresponding to the preset drilling position needs to be milled and windowed, and then radial hydraulic jet flow is performed on the well wall after the casing is windowed.
Specifically, a hydraulic radial jet device connected with the coiled tubing in a downward mode enters a preset position of a horizontal shaft to perform radial hydraulic jet. After the drilling of the first radial hole is finished, the coiled tubing is lifted according to the design to sequentially drill the subsequent radial boreholes. And after drilling all radial boreholes in the section, replacing the fracturing pipe column to perform fracturing of the section, and after fracturing, putting the bridge plug down to drill the next section of radial boreholes.
S104: performing carbon dioxide fracturing on the radial well;
wherein, carrying out carbon dioxide fracturing to radial well includes: liquid carbon dioxide is injected into the horizontal wellbore by a pump.
Specifically, after the high-pressure liquid carbon dioxide is injected into the radial well, a radial well stress field with extremely complex stress distribution can be formed under the interference between radial wells, the distribution of the original stress is changed, and meanwhile, the carbon dioxide has the characteristics of good diffusivity, zero surface tension and the like and is extremely easy to enter the microcracks and open the microcracks, so that a complex fracture network mainly formed by opening the microcracks can be formed in the radial well stress field in the carbon dioxide fracturing stage, as shown in fig. 5.
S106: and performing hydraulic fracturing on the radial well subjected to the carbon dioxide fracturing.
Wherein performing hydraulic fracturing on the radial well comprises: the water-based fracturing fluid is injected into the horizontal wellbore by a pump.
Wherein the water-based fracturing fluid is sand-carrying fracturing fluid.
Specifically, after carbon dioxide fracturing, conventional hydraulic fracturing is carried out, so that the microcracks opened in the carbon dioxide fracturing stage are further opened and expanded, an effectively opened fracture network is formed in the multi-radial well stress field range, and the effect of volume fracturing is achieved; further hydraulic fracturing can form a new fracture initiation point at the tail end of the radial well, main fractures are gradually formed, at the moment, a homogeneous stratum can form a plurality of main fractures, the oil drainage area is effectively increased, and the development effect is improved, as shown in fig. 6.
The radial well forms a corresponding radial well stress field during fracturing, and a fitted graph of the distribution range of the radial well stress field is an ellipse.
And the well spacing range among the plurality of radial wells is 0.5b < L < b, wherein L is the well spacing, and b is the short axis length of a fitting graph of the stress field distribution range of the radial wells.
Specifically, each stress field can be equivalent to a geometric figure, such as an ellipse, and the simple geometric figure can achieve the fitting precision of the stress field distribution area of the single radial well. An ellipse is used as a fitting graph of the stress field distribution range of the single radial well, and as shown in fig. 3, the change of the ellipse with the length of the major axis a and the length of the minor axis b can represent different reservoir parameters and fracture parameters. a. The value of b is determined by experiment or numerical simulation.
The well arrangement scheme of the multi-radial well at the horizontal well section is mainly controlled by the inter-well distance L of the radial well. When the well spacing L is larger than b, the stress fields of the two radial wells are not overlapped or interfered with each other; when the well spacing L < b, the stress fields of the two radial wells are superposed, and a cross-well interference phenomenon occurs, as shown in fig. 4. The inter-well interference phenomenon of the radial well can cause the inter-well area to form a complex stress field, so that the inter-well area has the condition of forming complex cracks and the effect of volume fracturing. Therefore, when the wells are distributed in a radial direction, the well spacing is smaller than the short axis length of the stress field distribution range fitting image, namely L < b, and meanwhile, the well spacing is not too small, so that the cost is too high, and therefore, 0.5b < L < b is comprehensively considered.
Example two
Fig. 7 shows a block diagram of a horizontal well volume fracturing system with radial wells combined with carbon dioxide fracturing, in accordance with an embodiment of the present invention.
As shown in fig. 7, the horizontal well volume fracturing system of the radial well in combination with carbon dioxide fracturing comprises:
a drilling device 102 for drilling a plurality of radial wells in a horizontal wellbore;
a first fracturing unit 104 for performing carbon dioxide fracturing on the radial well;
and the second fracturing device 106 is used for performing hydraulic fracturing on the radial well after the carbon dioxide fracturing is performed.
The radial well forms a corresponding radial well stress field during fracturing, and a fitted graph of the distribution range of the radial well stress field is an ellipse; the well spacing range between the plurality of radial wells is 0.5b < L < b, wherein L is the well spacing and b is the minor axis length of the fitted graph of the radial well stress field distribution range.
Wherein drilling a plurality of radial wells in a horizontal wellbore comprises: if the horizontal well is an open hole well completion, radial hydraulic jet flow is carried out at a preset position, and a radial well is drilled; if the horizontal well is completed by the casing, windowing is carried out on the casing at a preset position, radial hydraulic jet flow is carried out on the well wall after the casing is windowed, and a radial well is drilled.
Wherein the drilling device 102 is a hydraulic radial jet device, and performing radial hydraulic jet at a preset position comprises: the hydraulic radial jet flow equipment is connected to a preset position through the coiled tubing, and radial hydraulic jet flow is carried out through the hydraulic radial jet flow equipment.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (10)
1. A horizontal well volume fracturing method combining radial well with carbon dioxide fracturing is characterized by comprising the following steps:
drilling a plurality of radial wells in a horizontal wellbore;
carbon dioxide fracturing the radial well;
and performing hydraulic fracturing on the radial well subjected to the carbon dioxide fracturing.
2. The method of horizontal well volume fracturing with radial well in combination with carbon dioxide fracturing of claim 1, wherein drilling a plurality of radial wells in a horizontal wellbore comprises:
if the horizontal well is an open hole well completion, radial hydraulic jet flow is carried out at a preset position, and a radial well is drilled;
if the horizontal well is completed by the casing, windowing is carried out on the casing at a preset position, radial hydraulic jet flow is carried out on the well wall after the casing is windowed, and a radial well is drilled.
3. The horizontal well volume fracturing method of radial well in combination with carbon dioxide fracturing, as claimed in claim 2, wherein said radial hydraulic jet at a preset location comprises: and connecting the hydraulic radial jet flow equipment to the preset position through the coiled tubing, and performing radial hydraulic jet flow through the hydraulic radial jet flow equipment.
4. The horizontal well volume fracturing method of radial well in combination with carbon dioxide fracturing as claimed in claim 1 wherein said carbon dioxide fracturing of radial wells comprises: injecting liquid carbon dioxide into the horizontal wellbore by a pump.
5. The horizontal well volume fracturing method of radial well in combination with carbon dioxide fracturing of claim 1, wherein the hydraulic fracturing of the radial well comprises: injecting a water-based fracturing fluid into the horizontal wellbore via a pump.
6. The horizontal well volumetric fracturing method of radial well in combination with carbon dioxide fracturing as claimed in claim 5 wherein the water-based fracturing fluid is a sand-carrying fracturing fluid.
7. The horizontal well volume fracturing method combining the radial well with the carbon dioxide fracturing, according to claim 1, is characterized in that the radial well forms a corresponding radial well stress field during fracturing, and a fitted graph of a distribution range of the radial well stress field is an ellipse.
8. The horizontal well volume fracturing method of claim 7 wherein the range of well spacing between the plurality of radial wells is 0.5b < L < b, where L is the well spacing and b is the minor axis length of the fitted pattern of the radial well stress field distribution range.
9. A horizontal well volume fracturing system combining radial well with carbon dioxide fracturing, the system comprising:
a drilling device for drilling a plurality of radial wells in a horizontal wellbore;
a first fracturing device for carbon dioxide fracturing the radial well;
and the second fracturing device is used for performing hydraulic fracturing on the radial well subjected to carbon dioxide fracturing.
10. The horizontal well volume fracturing system combining radial well with carbon dioxide fracturing as claimed in claim 9, wherein the radial well forms a corresponding radial well stress field when fractured, and the fitted graph of the distribution range of the radial well stress field is an ellipse; the well spacing range between the plurality of radial wells is 0.5b < L < b, wherein L is the well spacing and b is the short axis length of a pattern fitted to the radial well stress field distribution range.
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