CN105986792B - Method for improving shallow reservoir recovery ratio - Google Patents
Method for improving shallow reservoir recovery ratio Download PDFInfo
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- CN105986792B CN105986792B CN201510091467.6A CN201510091467A CN105986792B CN 105986792 B CN105986792 B CN 105986792B CN 201510091467 A CN201510091467 A CN 201510091467A CN 105986792 B CN105986792 B CN 105986792B
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Abstract
The invention relates to a method for improving the recovery ratio of a shallow oil reservoir. The method selects an oil layer which generates horizontal cracks through fracturing by means of three-dimensional ground stress comparison, crack monitoring and the like, and the horizontal cracks are generated at the top and the bottom of the oil layer respectively through fracturing. Water is injected into the top of the oil layer, oil is extracted from the bottom of the oil layer, uniform water displacement is formed, water displacement energy is fully utilized, and the oil reservoir recovery ratio is improved.
Description
Technical Field
The invention belongs to the technical field of oil and gas field development, relates to a method for improving the recovery ratio of a shallow reservoir, and particularly relates to a method for improving the recovery ratio of the shallow reservoir by fracturing and water flooding.
Background
Hydraulic fracturing is an effective means to increase the production of low permeability oil and gas wells. Hydraulic fracturing creates fractures in the formation that may be vertical, horizontal, or complex, with fracture morphology primarily determined by the reservoir's depth of burial and stress state. In shallow oil and gas reservoirs with the burial depth of less than 1000m, horizontal fractures are easy to form by fracturing. How to fully exert the yield increasing effect of the fractured horizontal cracks; particularly, under the condition of water flooding, how to effectively increase the water flooding range and improve the oil reservoir recovery ratio is an important problem in shallow oil reservoir development. At present, more theoretical and technical researches such as well arrangement modes and the like are carried out on the development of vertical fracture water injection, but the research of improving the recovery ratio of horizontal fractures of shallow oil reservoirs is still blank.
Disclosure of Invention
The invention aims to solve the technical problem of providing a method for improving the recovery ratio of a shallow oil reservoir aiming at the defects of the prior art. The method comprises the steps of well arrangement on a production target layer, water injection on the top of the production target layer and oil extraction on the bottom of the production target layer. The method designs a novel well arrangement and fracturing mode aiming at the characteristic that horizontal cracks are formed by fracturing of the shallow oil reservoir, enlarges the sweep range of a water injection well, forms an even and efficient displacement mode, and improves the recovery ratio of the shallow oil reservoir.
Therefore, the invention provides a method for improving the recovery ratio of a shallow reservoir, which comprises the steps of well distribution, water injection at the top of a mining target layer and oil extraction at the bottom of the mining target layer.
The production target formation is preferably a shallow reservoir that fractures to create horizontal fractures.
In some embodiments of the invention, horizontal fractures formed by perforation or fracturing are water injected at the top of the production target formation. Horizontal fracture water injection by fracturing is preferably made at the top of the production target zone. And (4) recovering oil from the horizontal cracks formed at the bottom of the mining target layer through fracturing. The horizontal crack is at least one.
According to the invention, the well placement comprises drilling a vertical well and/or a horizontal well.
The method also comprises the step of selecting a mining target layer (oil layer) with horizontal fractures generated by fracturing through methods of three-dimensional ground stress comparison, fracture monitoring and the like before well distribution.
In some embodiments of the invention, a vertical well is drilled through a production target formation, the vertical well is cemented, water is injected at the top of the production target formation, and oil is produced at the bottom of the production target formation.
In one embodiment, a vertical well is drilled through the reservoir and fractured once at each of the bottom and top of the reservoir in the vertical well, creating one horizontal fracture; or top perforation, bottom fracturing. And water injection at the top and oil extraction at the bottom are realized through the same-well injection and extraction downhole pipe column.
In some embodiments of the invention, a straight well is drilled through a production target formation and cemented; drilling a horizontal well corresponding to the vertical well, and performing fracturing or open hole or perforation completion on the horizontal well; and injecting water through the horizontal well, and extracting oil at the bottom of the exploitation target layer. Water is injected into the top of a mining target layer (oil layer) and oil is extracted from the bottom of the mining target layer (oil layer) to form uniform water displacement, so that water displacement energy is fully utilized, and the oil reservoir recovery ratio is improved.
In one embodiment, drilling the horizontal well corresponding to the vertical well is drilling the horizontal well section at the windowed side of the section of the vertical well above the production target zone.
In another embodiment, drilling a horizontal well corresponding to a vertical well is drilling a horizontal well at the top of the production target formation within a range that creates horizontal fractures around the vertical well.
In one embodiment, a straight well is drilled through the oil formation, the straight well is cemented, and the bottom of the formation is fractured to create horizontal fractures. And (3) drilling a horizontal well at the window side of the well section of the vertical well, which is positioned at the upper part of the mining target layer, or drilling a horizontal well in the range of generating horizontal cracks around the vertical well, wherein the horizontal section is positioned at the top of the mining target layer (oil layer). Horizontal well fracturing or open hole or perforated completion. And injecting water through the horizontal well, and extracting oil from the lower cracks.
In one embodiment of the invention, one horizontal well is drilled at each of the top and bottom of the production target zone; top horizontal well fracturing or open hole or perforated completion. The bottom horizontal well is fractured to create at least one horizontal fracture. Water is injected through the top horizontal well, and oil is extracted through the bottom horizontal well. And the horizontal sections of the two horizontal wells form any included angle.
In one embodiment, a horizontal well is drilled at each of the top and bottom of the production target zone, and the horizontal sections of the horizontal well may be at any angle. Top horizontal well fracturing or open hole or perforated completion; the bottom horizontal well fractures one or more horizontal fractures. Water is injected through the top horizontal well, and oil is extracted through the bottom horizontal well.
The term "horizontal well section" used in the present invention refers to a well section in the horizontal direction of a new well which is drilled at a certain depth of a vertical well and sidetracked, and the well section and the vertical well together form a horizontal well.
In the invention, the fracturing or open hole or perforation completion of the horizontal well and the water injection through the horizontal well are carried out in the horizontal section of the horizontal well.
The invention has reasonable design, simple process and convenient operation, and can be widely used for shallow reservoir development; and by fracturing horizontal cracks at the top and the bottom of a mining target layer and injecting water at the top, uniform water flooding is formed. And (3) oil recovery is performed at the bottom, water drive energy is fully utilized, and the oil reservoir recovery ratio is improved. The method is mainly applied to the development of shallow low-permeability oil reservoirs, shallow oil is hidden in the Ordos basin, the Songliao basin and the like, the distribution is wide, and the application prospect is wide.
Drawings
The invention will be described below with reference to the accompanying drawings.
FIG. 1 is a schematic representation of well placement and fracturing in example 1;
FIG. 2 is a schematic diagram of well placement and fracturing in example 2;
FIG. 3 is a schematic diagram of well placement and fracturing in example 3;
FIG. 4 is a schematic diagram of well placement and fracturing in example 4;
FIG. 5 is a schematic diagram of well placement and fracturing in example 5;
FIG. 6 is a schematic diagram of well placement and fracturing in example 6;
FIG. 7 is a schematic diagram of well placement and fracturing in example 7;
FIG. 8 is a schematic diagram of well placement and fracturing in example 8;
FIG. 9 is a schematic diagram of well placement and fracturing in example 9;
the reference numerals in the figures have the following meanings: 1, vertical well; 2, mining the horizontal fracture at the top of the target layer; 3, the direction of oil displacement by water; 4, mining the horizontal fracture at the bottom of the target layer; 5, perforating a water injection layer at the top of the mining target layer; 6 sidetrack drilling a horizontal well section; and 7. horizontal wells.
Detailed Description
In order that the invention may be more readily understood, the following detailed description of the invention is given, with reference to the accompanying examples and drawings, which are given by way of illustration only and are not intended to limit the scope of the invention.
Examples
Example 1:
selecting an oil layer with horizontal cracks generated by fracturing through three-dimensional ground stress comparison, crack monitoring and other means, drilling a vertical well through a mining target layer, injecting water at the top of the mining target layer, and extracting oil at the bottom of the mining target layer.
As shown in fig. 1, a vertical well is drilled through the reservoir and fractured once at the bottom and top of the reservoir, respectively, in the vertical well, creating one horizontal fracture each. The results show that compared with the traditional well arrangement and fracturing mode, the well arrangement and fracturing carried out by the method can improve the initial yield of the oil well by 185 percent and improve the recovery rate by 5.7 percent.
Example 2:
as shown in fig. 2, the well placement and fracturing of example 2 was the same as in example 1, except for the top perforation completion. The results show that compared with the traditional well arrangement and fracturing mode, the well arrangement and fracturing recovery efficiency by adopting the method is improved by 3.8 percent.
Example 3:
and selecting a production target layer by adopting the same method as the embodiment 1, injecting water at the top of the production target layer, and extracting oil at the bottom of the production target layer.
As shown in fig. 3, a vertical well is drilled through the reservoir and fractured at the bottom of the reservoir, creating horizontal fractures. And (4) a horizontal well section is drilled on the side of the window of the vertical well, and the horizontal well section is positioned at the top of the oil reservoir. And performing perforation completion on the horizontal well section. And injecting water through the horizontal well section, and extracting oil through the lower cracks. The results show that compared with the traditional well arrangement and fracturing mode, the well arrangement and fracturing recovery efficiency by adopting the method is improved by 4.2 percent.
Example 4:
as shown in fig. 4, the well placement and fracturing of example 4 is the same as example 3, except that a new horizontal well is drilled within the range of horizontal fractures from vertical fractures, the horizontal segment being at the top of the reservoir. And (4) perforating a horizontal well. And injecting water through the horizontal well, and extracting oil from the lower cracks. The results show that compared with the traditional well arrangement and fracturing mode, the well arrangement and fracturing recovery efficiency by adopting the method is improved by 5.3 percent.
Example 5:
as shown in fig. 5, the well placement and fracturing pattern of example 5 was the same as example 4, except that the horizontal well fractured two horizontal fractures. The results show that compared with the traditional well arrangement and fracturing mode, the well arrangement and fracturing recovery efficiency by adopting the method is improved by 6.0 percent.
Example 6:
selecting a mining target layer by adopting the same method as the embodiment 1, and respectively drilling a horizontal well at the top and the bottom of the mining target layer as shown in FIG. 6; completing the top horizontal well by perforating; the bottom horizontal well generates two horizontal cracks through fracturing; water is injected through the top horizontal well, and oil is extracted through the bottom horizontal well. The included angle between the two horizontal wells is 0 degree. The results show that compared with the traditional well arrangement and fracturing mode, the well arrangement and fracturing recovery efficiency by adopting the method is improved by 8.4 percent.
Example 7:
as shown in fig. 7, the well placement and fracturing pattern of example 7 was the same as example 6, except that the top horizontal well fractured two horizontal fractures. The results show that compared with the traditional well arrangement and fracturing mode, the well arrangement and fracturing recovery efficiency by adopting the method is improved by 10.0 percent.
Example 8:
as shown in fig. 8, the well placement and fracturing pattern of example 8 is the same as example 6, except that the angle between the two horizontal wells is 180 °. The results show that compared with the traditional well arrangement and fracturing mode, the well arrangement and fracturing recovery efficiency by adopting the method is improved by 8.5 percent.
Example 9:
as shown in fig. 9, the well placement and fracturing pattern of example 9 was the same as example 7, except that the angle between the two horizontal wells was 180 °. The results show that compared with the traditional well arrangement and fracturing mode, the well arrangement and fracturing recovery efficiency by adopting the method is improved by 10.1 percent.
According to the embodiment, the method provided by the invention can be used for fracturing the horizontal crack at the top and the bottom of the oil-gas reservoir and injecting water into the upper part of the oil-gas reservoir to form uniform water flooding. And the lower part is used for oil extraction, the water drive energy is fully utilized, and the oil reservoir recovery ratio is improved.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (7)
1. The method for improving the recovery ratio of the shallow reservoir comprises the steps of well arrangement, wherein the well arrangement comprises the drilling of a vertical well and/or a horizontal well, water injection is carried out on the top of a production target layer, oil extraction is carried out on the bottom of the production target layer, radially-extending horizontal fractures are formed on the top of the production target layer through fracturing and are injected with water, radially-extending horizontal fractures are formed on the bottom of the production target layer through fracturing and are subjected to displacement mode oil extraction, the production target layer is used for oil extraction in the shallow reservoir with the burial depth lower than 1000m, and the horizontal fractures formed through fracturing tend to extend in the horizontal planes corresponding to the top and the bottom of the production target layer in a horizontally radial mode, so that the swept range of a water injection well in the horizontal direction is expanded.
2. The method of claim 1, wherein a vertical well is drilled through the production target formation, the vertical well is cemented and water is injected at the top of the production target formation and oil is produced at the bottom of the production target formation.
3. The method of claim 1, wherein a straight well is drilled through the production target formation and cemented; drilling a horizontal well corresponding to the vertical well, and performing fracturing well completion on the horizontal well; and injecting water through the horizontal well, and extracting oil at the bottom of the exploitation target layer.
4. The method of claim 3, wherein drilling the horizontal well corresponding to the vertical well is drilling the horizontal well section at a windowed sidetracking section of the vertical well above the production target zone.
5. The method of claim 3, wherein drilling the horizontal well in response to the vertical well is drilling a horizontal well at the top of the production target formation within a range that creates horizontal fractures around the vertical well.
6. The method of claim 1, wherein one horizontal well is drilled at each of the top and bottom of the production target zone; fracturing and completing the top horizontal well; the bottom horizontal well generates at least one horizontal crack through fracturing; water is injected through the top horizontal well, and oil is extracted through the bottom horizontal well.
7. The method according to claim 6, wherein the horizontal sections of the two horizontal wells are at any included angle.
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| CN109339753A (en) * | 2018-09-14 | 2019-02-15 | 山东石大油田技术服务股份有限公司 | A method of well pattern is remolded using directional sidetracking adjustment water injection well target position |
| CN110939412B (en) * | 2019-12-13 | 2021-07-20 | 延长油田股份有限公司富县采油厂 | Development method for realizing advanced water injection and early water injection by utilizing horizontal well |
| CN114293958B (en) * | 2021-12-13 | 2023-10-20 | 常州大学 | Method for efficiently developing heavy oil reservoir containing bottom water by adopting double horizontal wells |
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| US4372381A (en) * | 1981-04-10 | 1983-02-08 | Mobil Oil Corporation | Method for recovery of oil from tilted reservoirs |
| CN101289932A (en) * | 2007-04-17 | 2008-10-22 | 长江大学 | Straight-line parallel flow water injection oil extraction method |
| CN102518421A (en) * | 2011-12-23 | 2012-06-27 | 中国石油大学(北京) | Physical simulation visualization experimental device and forming method thereof |
| CN102678096A (en) * | 2012-05-08 | 2012-09-19 | 中国石油天然气股份有限公司 | Hot water assisted gravity drainage method for mining high pour-point oil deposit |
| CN104141481A (en) * | 2013-05-06 | 2014-11-12 | 中国石油天然气股份有限公司 | Well spacing method of ultralow-permeability tight-oil reservoir horizontal well |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4372381A (en) * | 1981-04-10 | 1983-02-08 | Mobil Oil Corporation | Method for recovery of oil from tilted reservoirs |
| CN101289932A (en) * | 2007-04-17 | 2008-10-22 | 长江大学 | Straight-line parallel flow water injection oil extraction method |
| CN102518421A (en) * | 2011-12-23 | 2012-06-27 | 中国石油大学(北京) | Physical simulation visualization experimental device and forming method thereof |
| CN102678096A (en) * | 2012-05-08 | 2012-09-19 | 中国石油天然气股份有限公司 | Hot water assisted gravity drainage method for mining high pour-point oil deposit |
| CN104141481A (en) * | 2013-05-06 | 2014-11-12 | 中国石油天然气股份有限公司 | Well spacing method of ultralow-permeability tight-oil reservoir horizontal well |
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