Horizontal well pattern and method of oil recovery for a tight reservoir

Abstract

The application discloses a horizontal well pattern and oil extraction method for a dense reservoir. The horizontal well pattern comprises a plurality of horizontal wells arranged in an upper oil layer in the dense reservoir, and a plurality of oil extraction horizontal wells and water injection horizontal wells arranged in an interval of a lower oil layer in the dense reservoir. The horizontal wells in the upper oil layer comprise gas injection horizontal wells. The lower oil layer is provided with horizontal wells at positions corresponding to positions of the horizontal wells in the upper oil layer, and at positions corresponding to positions between two adjacent horizontal wells in the upper oil layer. The horizontal well pattern can be used to supplement formation energy and improve recovery rate of the dense oil / shale oil well by means of the oil extraction method combining gas injection and water injection.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil development, in particular to a horizontal well pattern and oil production method for a tight reservoir. BACKGROUND

[0002] The shale oil / tight oil reservoir matrix has low percolation capacity, and usually uses fracturing to improve the percolation capacity of the formation. After the horizontal well is fractured and put into production, the depletion type development is easy to cause insufficient formation energy. How to supplement the formation energy and improve the recovery rate is a problem that needs to be considered in the development of tight oil / shale oil. Under the condition that there is a interlayer between the upper oil layer (oil layer I) and the lower oil layer (oil layer II), after the horizontal well is fractured, the oil layer I and the oil layer II may be communicated through the fractures. Under the condition that the oil layer I and the oil layer II are communicated through the fractures, a method for supplementing the formation energy of the oil well and improving the recovery rate of the oil well needs to be explored. SUMMARY

[0003] In order to at least partially solve the above technical problems existing in the prior art, the present application is made by the inventors, and through specific embodiments, a horizontal well pattern and oil production method for a tight reservoir are provided to provide help for the development of the tight reservoir.

[0004] In a first aspect, an embodiment of the present application provides a horizontal well pattern for a tight reservoir, comprising a plurality of horizontal wells arranged in an upper oil layer in the tight reservoir, and a plurality of oil production horizontal wells and water injection horizontal wells arranged in an interval in a lower oil layer in the tight reservoir, wherein the horizontal wells in the upper oil layer comprise gas injection horizontal wells.

[0005] The lower oil layer is arranged with horizontal wells at corresponding positions of the horizontal wells in the upper oil layer and at corresponding positions of the middle positions between adjacent two horizontal wells in the upper oil layer.

[0006] In some embodiments, the well spacing of the horizontal wells in the upper oil layer is twice the well spacing of the horizontal wells in the lower oil layer.

[0007] In some embodiments, the fracturing scale of the horizontal wells in the upper oil layer is greater than the fracturing scale of the horizontal wells in the lower oil layer.

[0008] In some embodiments, the horizontal wells in the upper oil layer are oil production horizontal wells and gas injection horizontal wells arranged in an interval; the adjacent 3 horizontal wells in the upper oil layer from the oil production horizontal well, and the adjacent 5 horizontal wells in the lower oil layer matched vertically form a well pattern unit; the adjacent 3 horizontal wells in the upper oil layer of a well pattern unit are an oil production horizontal well, a gas injection horizontal well and an oil production horizontal well respectively, and the adjacent 5 horizontal wells in the lower oil layer are an oil production horizontal well, a water injection horizontal well, an oil production horizontal well, a water injection horizontal well and an oil production horizontal well respectively.

[0009] In some embodiments, the horizontal wells in the upper oil layer are all gas injection horizontal wells.

[0010] In some embodiments, each of the production horizontal well, the gas injection horizontal well and the water injection horizontal well is a fractured horizontal well.

[0011] In the second aspect, the embodiments of the present application provide a horizontal well pattern deployment method, comprising deploying any of the above horizontal well patterns.

[0012] In the third aspect, the embodiments of the present application provide a method for oil production in a tight reservoir, comprising carrying out combined gas injection and water injection oil production based on any of the above horizontal well patterns.

[0013] In some embodiments, the carrying out of the combined gas injection and water injection oil production comprises multiple injection-production cycles until the development effect does not meet a first set requirement.

[0014] In some embodiments, each injection-production cycle comprises:

[0015] an injection soak phase, in which the production horizontal well is shut in, the gas injection horizontal well is injected with gas and then shut in after injection, and the water injection horizontal well is injected with water and then shut in after injection;

[0016] a production phase, in which all the horizontal wells are simultaneously opened for oil production until the production effect does not meet a second set requirement.

[0017] The above technical solutions provided by the embodiments of the present application have at least the following beneficial effects:

[0018] The horizontal well pattern for a tight reservoir provided by the embodiments of the present application comprises multiple horizontal wells deployed in an upper oil layer in the tight reservoir, and multiple production horizontal wells and water injection horizontal wells deployed in an interval of a lower oil layer in the tight reservoir, wherein the horizontal wells in the upper oil layer comprise gas injection horizontal wells; the lower oil layer, at positions corresponding to the horizontal wells in the upper oil layer, and at positions corresponding to the middle positions between two adjacent horizontal wells in the upper oil layer, are each provided with a horizontal well. By using the combined mode of injecting gas by the gas injection horizontal wells in the upper oil layer and injecting water by the water injection horizontal wells in the lower oil layer, the formation energy of the oil well is supplemented and the oil well recovery rate is improved.

[0019] Other features and advantages of the present application will be set forth in the following description, and in part will become apparent to those skilled in the art from the description, or can be learned by practice of the present application. The objects and other advantages of the present application can be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.

[0020] The technical solutions of the present application will be further described in detail below with the aid of the accompanying drawings and embodiments. BRIEF DESCRIPTION OF DRAWINGS

[0021] The accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this specification, illustrate embodiments of the present application and are meant to explain the present application and are not intended to limit the present application. In the drawings:

[0022] Figure 1 Figure 1 is a schematic diagram of a horizontal well network with upper gas injection and lower water injection for an embodiment of the present application.

[0023] Figure 2 Figure 2 is a schematic diagram of a horizontal well deployment for an embodiment of the present application.

[0024] Figure 3 Figure 3 is a schematic diagram of a horizontal well network with upper water injection and lower gas injection for an embodiment of the present application. DETAILED DESCRIPTION

[0025] Exemplary embodiments of the present disclosure will be described herein below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it is understood that the present disclosure can be embodied in various forms without being 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 present disclosure to those skilled in the art.

[0026] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, preferred methods and materials are described herein. All publications mentioned in this specification are herein incorporated by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any reference is not an admission that it is prior art with respect to the present application. All documents mentioned herein are incorporated by reference in their entirety.

[0027] In the description of the present application, it is to be understood that the terms "including", "comprising", "having", "containing", or "involving", and the like, are meant to encompass the cases where one or more features, integers, or steps are included, contained, or involved. However, these terms are not meant to be construed to limit the present application to only those embodiments which contain the features, integers, or steps.

[0028] The shale oil / dense oil reservoir matrix has low percolation capacity, and usually, fracturing is used to improve the percolation capacity of the formation. After the horizontal well is fractured and put into production, the depletion type development is easy to cause insufficient formation energy. How to supplement the formation energy of the oil well and improve the recovery rate is a problem to be considered in the development of dense oil / shale oil. In the case that there is a barrier layer between the upper oil layer (oil layer I) and the lower oil layer (oil layer II), after the horizontal well is fractured, the oil layer I and the oil layer II can be communicated through the fractures. Under the condition that the oil layer I and the oil layer II are communicated through the fractures, a horizontal well pattern and a production method for dense reservoirs are designed. The horizontal well pattern and the production method for dense reservoirs provided by the embodiments of the present application can supplement the formation energy of the oil well and improve the recovery rate of the oil well.

[0029] Embodiment one

[0030] The embodiment one of the present application provides a horizontal well pattern for dense reservoirs, referring to FIG. 1, there is a barrier layer between the upper oil layer (oil layer I) and the lower oil layer (oil layer II) of the dense reservoir, and the deployed horizontal well pattern comprises a plurality of horizontal wells deployed in the upper oil layer in the dense reservoir, and a plurality of production horizontal wells and water injection horizontal wells deployed in the lower oil layer in the dense reservoir. Figure 1

[0031] The horizontal wells in the upper oil layer comprise gas injection horizontal wells; the production horizontal wells and the water injection horizontal wells in the lower oil layer are deployed in intervals. The positions of the horizontal wells in the upper oil layer are consistent in the horizontal direction, and the positions of the horizontal wells in the lower oil layer are consistent in the horizontal direction.

[0032] The lower oil layer is provided with a horizontal well at a corresponding position of the horizontal well in the upper oil layer and at a corresponding position of the middle position between two adjacent horizontal wells in the upper oil layer.

[0033] Specifically, the corresponding position herein refers to a position consistent in the vertical direction. In actual development, it is difficult to achieve complete consistency in the vertical direction due to the influence of geological factors and the like, and therefore the consistency in the vertical direction refers to a deviation in the vertical direction within a set range.

[0034] Figure 1 The horizontal wells in the upper oil layer are all gas injection horizontal wells. Figure 1 In the specific embodiment, the horizontal well 11 in the upper oil layer (oil layer I) is provided with a production horizontal well 21 at a vertically corresponding position of the lower oil layer (oil layer II); the horizontal well 12 in the upper oil layer (oil layer I) is provided with a production horizontal well 23 at a vertically corresponding position of the lower oil layer (oil layer II); and the horizontal well 11 and the horizontal well 12 in the upper oil layer (oil layer I) are provided with a water injection horizontal well 22 at a vertically corresponding position of the middle position between the two horizontal wells.

[0035] The well spacing of the horizontal wells in the upper oil layer is twice the well spacing of the horizontal wells in the lower oil layer.​Figure 2 As shown, the well spacing of the horizontal well in the upper oil layer (oil layer I) is 2L, and the well spacing of the horizontal well in the lower oil layer (oil layer II) is L.

[0036] Since the well spacing of the horizontal well in the upper oil layer is greater than the well spacing of the horizontal well in the lower oil layer, the fracturing scale of the horizontal well in the upper oil layer is greater than the fracturing scale of the horizontal well in the lower oil layer.

[0037] In some embodiments, the horizontal well in the upper oil layer is an oil production horizontal well and a gas injection horizontal well arranged at intervals. An oil production method of upper interval well gas injection huff and puff and lower interval well water injection huff and puff can be realized. The adjacent 3 horizontal wells in the upper oil layer from the oil production horizontal well, and the vertically matched adjacent 5 horizontal wells in the lower oil layer form a well pattern unit. The adjacent 3 horizontal wells in the upper oil layer of a well pattern unit are an oil production horizontal well, a gas injection horizontal well and an oil production horizontal well respectively, and the adjacent 5 horizontal wells in the lower oil layer are an oil production horizontal well, a water injection horizontal well, an oil production horizontal well, a water injection horizontal well and an oil production horizontal well respectively.

[0038] Referring to Figure 3 As shown, the oil production horizontal well 11, the gas injection horizontal well 12 and the oil production horizontal well 13 in the upper oil layer (oil layer I), and the oil production horizontal well 21, the water injection horizontal well 22, the oil production horizontal well 23, the water injection horizontal well 24 and the oil production horizontal well 25 in the lower oil layer (oil layer II) form a well pattern unit.

[0039] In some embodiments, the horizontal well in the upper oil layer is a gas injection horizontal well. An oil production method of upper gas injection huff and puff and lower interval well water injection huff and puff can be realized.

[0040] The horizontal well pattern for the tight reservoir provided by the embodiment one of the present application comprises a plurality of horizontal wells arranged in the upper oil layer of the tight reservoir, and a plurality of oil production horizontal wells and water injection horizontal wells arranged at intervals in the lower oil layer of the tight reservoir. The horizontal wells in the upper oil layer comprise gas injection horizontal wells. The lower oil layer is arranged with horizontal wells at the corresponding positions of the horizontal wells in the upper oil layer and the corresponding positions of the middle positions of the adjacent two horizontal wells in the upper oil layer. By using the combination of gas injection by the gas injection horizontal wells in the upper oil layer and water injection by the water injection horizontal wells in the lower oil layer, the formation energy of the oil well is supplemented and the oil recovery rate is improved.

[0041] Embodiment two

[0042] The embodiment two of the present application provides an oil production method for the tight reservoir, which is based on any of the above horizontal well patterns to carry out gas injection and water injection combined oil production.

[0043] Further, the gas injection and water injection combined oil production includes a plurality of injection and production cycles until the development effect does not meet the first set requirement.

[0044] Wherein each injection-production cycle specifically comprises:

[0045] (1) Injection and soaking phase

[0046] The gas injection horizontal well injects gas and soaks after injection, and the water injection horizontal well injects water and soaks after injection. When the gas injection horizontal well injects fluid and soaks, or when the water injection horizontal well injects water and soaks, the production horizontal well is shut in.

[0047] (2) Production phase

[0048] After the soaking of the gas injection horizontal well ends, and the soaking of the water injection horizontal well ends, the production horizontal well, the gas injection horizontal well and the water injection horizontal well are opened for production, until the production effect does not meet the second set requirement, and returns to the injection and soaking phase.

[0049] Repeat steps (1) and (2) to carry out multiple injection-production cycles, until the development effect does not meet the first set requirement.

[0050] In the foregoing detailed description, various features are grouped together in single embodiments for the purpose of streamlining the disclosure. This method of disclosure should not be interpreted as reflecting a necessity of more features than are expressly identified in each claim. Rather, such disclosure of various groups of features in single embodiments reflects the relatedness of the groups in that the single embodiment can be constructed without the related groups. The claims, thus, may

[0051] The foregoing description includes example of one or more embodiments. Of course, not all possible combinations of components or methods described above will be described as embodiments. A person of ordinary skill in the art will recognize that further combinations and permutations of various embodiments are possible. Accordingly, the embodiments described herein are intended to embrace all such alterations, modifications and variations going to the scope of the claims. Additionally, description of the term "comprising" over the description or claims means to include, like the term "including", as interpreted by the expression "including, but not limited to". Furthermore, any term "or" used in the description or claims means "non-exclusive or".

Claims

1. A horizontal well pattern for tight reservoirs, characterized in that, The system includes multiple horizontal wells deployed in the upper oil layer of a tight reservoir, and multiple production horizontal wells and water injection horizontal wells deployed at intervals in the lower oil layer of the tight reservoir. The horizontal wells in the upper oil layer include gas injection horizontal wells. Each production horizontal well, gas injection horizontal well, and water injection horizontal well is a fractured horizontal well. There is a partition between the upper oil layer and the lower oil layer, and the upper oil layer and the lower oil layer are connected by fractures. The lower oil layer has horizontal wells deployed at the corresponding positions of the horizontal wells in the upper oil layer, and at the corresponding positions between two adjacent horizontal wells in the upper oil layer.

2. The horizontal well network as described in claim 1, characterized in that, The well spacing of the horizontal wells in the upper oil layer is twice the well spacing of the horizontal wells in the lower oil layer.

3. The horizontal well network as described in claim 2, characterized in that, The horizontal wells in the upper oil layer are oil production horizontal wells and gas injection horizontal wells deployed at intervals; Three adjacent horizontal wells starting from the production horizontal well in the upper oil layer, and five adjacent horizontal wells in the lower oil layer that match vertically, constitute a well network unit. In a well network unit, the three adjacent horizontal wells in the upper oil layer are a production horizontal well, a gas injection horizontal well, and a production horizontal well, respectively. The five adjacent horizontal wells in the lower oil layer are a production horizontal well, a water injection horizontal well, a production horizontal well, a water injection horizontal well, and a production horizontal well, respectively.

4. The horizontal well network as described in claim 2, characterized in that, All horizontal wells in the upper oil layer are gas injection horizontal wells.

5. A method for deploying a horizontal well network, characterized in that, This includes deploying the horizontal well network as described in any one of claims 1 to 4.

6. A method for oil recovery from tight reservoirs, characterized in that, include: Based on the horizontal well pattern described in any one of claims 1 to 4, combined gas injection and water injection oil production can be carried out.

7. The method as described in claim 6, characterized in that, The aforementioned combined gas and water injection oil recovery includes multiple injection and production cycles until the development effect no longer meets the first set requirements.

8. The method as described in claim 7, characterized in that, Each injection-production cycle includes: During the injection and simmering stage, oil production horizontal wells are shut off, gas injection horizontal wells are injected with gas and then simmered, and water injection horizontal wells are injected with water and then simmered. During the extraction phase, all horizontal wells are opened simultaneously to produce oil until the production results no longer meet the second set requirements.

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