CN110952967B

CN110952967B - Thickened oil recovery method

Info

Publication number: CN110952967B
Application number: CN201811130344.9A
Authority: CN
Inventors: 于庆森; 董宏; 杨柳; 李雪松; 王倩; 陈燕辉; 刘刚
Original assignee: Petrochina Co Ltd
Current assignee: Petrochina Co Ltd
Priority date: 2018-09-27
Filing date: 2018-09-27
Publication date: 2021-09-28
Anticipated expiration: 2038-09-27
Also published as: CN110952967A

Abstract

The invention provides a heavy oil recovery method, which is used for a heavy oil reservoir, wherein an interlayer is arranged between an upper oil layer and a lower oil layer of the heavy oil reservoir, a reverse nine-point well group is arranged in the heavy oil reservoir, and the heavy oil recovery method comprises the following steps: respectively putting packers into side wells and corner wells of the reverse nine-point well group, wherein the packers are positioned at the positions of the separation layers; injecting steam into the lower oil layer through the side well and the corner well so as to perform steam stimulation in the lower oil layer; and injecting steam into at least the upper oil layer through the steam injection wells of the anti-nine-point well group so as to drive the steam in the upper oil layer. By the technical scheme provided by the invention, the problem of low recovery ratio of the heavy oil reservoir in the prior art can be solved.

Description

Thickened oil recovery method

Technical Field

The invention relates to the technical field of oil exploitation, in particular to a thickened oil exploitation method.

Background

Steam huff and puff and steam flooding are the main development modes of heavy oil reservoirs, but the reservoir heterogeneity of heavy oil reservoirs in many areas is serious, the steam overlap is serious, the oil reservoirs absorb steam unevenly in the depth direction, the extraction degree at the top of the oil reservoir is high, the extraction degree at the bottom is low, particularly, a stable interlayer exists in the oil reservoir, and the permeability difference between the upper oil layer and the lower oil layer of the interlayer is large. After 4-5 times of oil reservoir huffing and puff, the upper oil layer has high extraction degree due to much steam absorption, and basically forms thermal communication; the lower oil layer has less absorption of steam and the oil layer has low utilization degree.

Disclosure of Invention

The invention provides a heavy oil recovery method, which aims to solve the problem of low recovery ratio of a heavy oil reservoir in the prior art.

In order to solve the problems, the invention provides a heavy oil recovery method, which is used for a heavy oil reservoir, wherein a separation layer is arranged between an upper oil layer and a lower oil layer of the heavy oil reservoir, and an anti-nine-point well group is arranged in the heavy oil reservoir, and the heavy oil recovery method comprises the following steps: respectively putting packers into side wells and corner wells of the reverse nine-point well group, wherein the packers are positioned at the positions of the separation layers; injecting steam into the lower oil layer through the side well and the corner well so as to perform steam stimulation in the lower oil layer; and injecting steam into at least the upper oil layer through the steam injection wells of the anti-nine-point well group so as to drive the steam in the upper oil layer.

Further, during the steam injection process in the steam injection well, the upper oil layer and the lower oil layer absorb the steam.

Further, the steam injection speed in the steam injection well is 60-70t/d, and the bottom hole dryness of the steam injection well is more than 70%.

Further, the intensity of the injected steam in the lower oil layer is 110-130t/m, and the speed of the injected steam is 60-70 t/d.

Furthermore, the bottom dryness of the side well and the corner well is more than 70 percent, and the soaking time of the side well and the corner well is 5 to 7 days.

Further, the packer is a thermal expansion type packer, and when steam is injected into the side well and the corner well, the packer can be expanded to seal the side well and the corner well.

Further, the packers can be retracted to avoid the side and corner wells when no steam is injected into the side and corner wells.

Furthermore, the side well and the corner well form a huff-puff well, and the heavy oil exploitation method further comprises the following steps: and adjusting injection and production parameters of the steam injection well and the huff and puff well until production is finished.

Further, the heavy oil recovery method is suitable for heavy oil reservoirs which are huffed and puff for multiple rounds.

Furthermore, the single-well throughput times of the heavy oil reservoir are more than 3, the upper oil layer of the heavy oil reservoir is in thermal communication, the interlayer thickness of the heavy oil reservoir is more than 2m, and the permeability level difference between the upper oil layer and the lower oil layer is more than 5.

By applying the technical scheme of the invention, the packers are respectively put into the side wells and the corner wells of the reverse nine-point well group of the heavy oil reservoir and are arranged at the positions of the separation layers, so that the upper oil layer and the lower oil layer can be separated by the packers, steam is injected into the lower oil layer through the side wells and the corner wells, steam huff and puff can be carried out on the lower oil layer, steam is injected into the upper oil layer through the steam injection well, and steam flooding can be carried out on the upper oil layer. The oil reservoir carries out steam huff and puff alone like this, can effectively use oil reservoir down, improves the extraction degree, and the oil reservoir adopts steam drive, can effectively utilize the oil mass of oil reservoir. The technical scheme combines steam huff and puff with steam flooding, and the recovery ratio of the heavy oil reservoir can be improved through the technical scheme of the invention.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 shows a schematic layout of an anti-nine well group in a heavy oil reservoir;

fig. 2 shows a schematic of the flow of steam in a heavy oil reservoir.

Wherein the figures include the following reference numerals:

11. applying an oil layer; 12. discharging an oil layer; 13. an interlayer; 21. a side well; 22. an angle well; 23. a steam injection well; 30. and (4) a packer.

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The embodiment of the invention provides a heavy oil recovery method, which is used for a heavy oil reservoir, wherein an interlayer 13 is arranged between an upper oil layer 11 and a lower oil layer 12 of the heavy oil reservoir, an anti-nine-point well group is arranged in the heavy oil reservoir, and the heavy oil recovery method comprises the following steps: respectively setting a packer 30 in a side well 21 and a corner well 22 of the reverse nine-point well group, wherein the packer 30 is positioned at the position of the interlayer 13; injecting steam into the lower reservoir 12 through the side wells 21 and corner wells 22 for steam stimulation in the lower reservoir 12; steam is injected into at least the upper reservoir 11 through the steam injection wells 23 of the anti-nine well group to perform steam flooding in the upper reservoir 11.

By applying the technical scheme of the invention, the packers 30 are respectively put into the side wells 21 and the corner wells 22 of the reverse nine-point well group of the heavy oil reservoir, and the packers 30 are arranged at the positions of the separation layers 13, so that the upper oil layer 11 and the lower oil layer 12 can be separated by the packers 30, steam is injected into the lower oil layer 12 through the side wells 21 and the corner wells 22, steam huff and puff can be carried out on the lower oil layer 12, steam is injected into the upper oil layer 11 through the steam injection wells, and steam flooding can be carried out on the upper oil layer 11. Lower oil reservoir 12 carries out steam alone like this and takes in and send out, can effectively use lower oil reservoir 12, improves the extraction degree, and upper oil reservoir 11 adopts steam to drive, can effectively utilize the oil mass of upper oil reservoir 11. The technical scheme combines steam huff and puff with steam flooding, and the recovery ratio of the heavy oil reservoir can be improved through the technical scheme of the invention.

In this embodiment, both the upper and

lower oil layers

11 and 12 absorb steam during the injection of steam into the steam injection well 23. Thus, the steam injected through the steam injection well 23 can be delivered to both the upper oil layer 11 to steam drive the upper oil layer 11 and the lower oil layer 12 to steam huff and puff the lower oil layer 12, which can improve the production efficiency.

In this embodiment, the steam injection rate in the steam injection well 23 is 60-70t/d (ton per day), and the bottom hole dryness of the steam injection well 23 is more than 70%. This provides sufficient steam to meet the process requirements for enhanced recovery.

In the present embodiment, the intensity of the injected steam in the lower oil layer 12 is 110-130t/m, and the speed of the injected steam is 60-70 t/d. This allows the process requirements to be met and sufficient steam to be injected.

In the embodiment, the bottom dryness of the side well 21 and the corner well 22 is more than 70%, and the soaking time of the side well 21 and the corner well 22 is 5-7 days. Thus, a good soaking effect can be ensured to improve the recovery of the thick oil.

In the present embodiment, the packer 30 is a thermal expansion packer 30, and when steam is injected into the side well 21 and the corner well 22, the packer 30 can be expanded to seal the side well 21 and the corner well 22. This allows the upper and

lower reservoirs

11, 12 to be separated by packers for independent steam stimulation in the lower reservoir 12. The thermal expansion packer 30 is expanded by heating and contracted by cooling, so that automatic operation can be realized. In this embodiment, packer 30 may be configured to expand to seal off lateral well 21 and corner well 22 when steam temperature is greater than 250 ℃.

In this embodiment, the packer 30 can be retracted to avoid the side well 21 and the corner well 22 when steam is not injected into the side well 21 and the corner well 22. This allows communication between the side wells 21 and the corner wells 22 for oil production through the side wells 21 and the corner wells 22. In oil production, the upper oil layer 11 and the lower oil layer 12 can be simultaneously produced through the side well 21 and the corner well 22.

In this embodiment, the side well 21 and the corner well 22 form a huff-and-puff well, and the heavy oil recovery method further includes: and adjusting the injection and production parameters of the steam injection well 23 and the huff and puff well until the production is finished. During production, the injection and production parameters of the steam injection well 23 and the huff and puff wells can be adjusted according to actual conditions to provide oil yield as much as possible.

The heavy oil exploitation method is particularly suitable for heavy oil reservoirs which are huffed and puff for multiple rounds. After 4-5 times of oil reservoir huffing and puff, the upper oil layer has high extraction degree due to much steam absorption, and basically forms thermal communication; the lower oil layer has less absorption of steam and the oil layer has low utilization degree. The method can effectively utilize the residual oil quantity of the upper oil layer 11 and the oil quantity with lower utilization rate of the lower oil layer 12, thereby improving the recovery ratio of the oil reservoir.

In the embodiment, the single-well throughput of the heavy oil reservoir is more than 3 rounds, the upper oil layer 11 of the heavy oil reservoir is in thermal communication, the thickness of the interlayer 13 of the heavy oil reservoir is more than 2m, and the permeability level difference between the upper oil layer 11 and the lower oil layer 12 is more than 5. For the heavy oil reservoir meeting the conditions, the recovery ratio of the heavy oil can be effectively improved.

To facilitate understanding of the present solution, a specific embodiment is described below.

1, carrying out coarse screening on an oil reservoir, wherein the selected oil reservoir is a 100 x 140m inverse nine-point well pattern, and has average throughput of 4 rounds, the oil reservoir burial depth of 242m, the thickness of an oil layer of 3.2m, the porosity of the oil layer of 21.5 percent and the permeability of the oil layer of 218 mD; the thickness of the lower oil layer is 5.6m, the porosity of the oil layer is 18.6 percent, and the permeability of the oil layer is 40 mD; the thickness of the middle interlayer is 2.3m, the development is stable, and the middle interlayer is a mudstone interlayer. The degassing viscosity of the crude oil at 20 ℃ is 2423mPa.s on average.

2, putting high-temperature packers into corner wells and side wells of the reverse nine-point well group at interlayer positions, putting an oil layer for steam huff and puff, wherein the steam injection speed is 65t/d, the steam strength is 120t/m, the dryness is 70%, and stewing is carried out for 5 days.

And 3, stopping soaking the corner well and the side well, starting steam injection of the steam injection well when the well is opened, wherein the steam injection speed is 60t/d, the dryness of the bottom of the steam injection well is 70%, and performing combined production on an upper oil layer and a lower oil layer.

Compared with the conventional swallowing and spitting and steam flooding, the average oil yield is increased from 1.5t/d to 3.0t/d, the final recovery ratio is increased by 10.0 percent, and the oil-steam ratio is increased by 0.1.

By the method, the steam swept volume can be improved, the oil reservoir bottom exploitation degree can be improved, and the recovery ratio of the heavy oil can be improved. The technical scheme of the invention can realize the following technical effects:

(1) the recovery degree of an upper oil layer is high under the steam overburden effect, heat communication is formed, the throughput effect is poor, and residual oil in a well can be effectively used by the rotary steam drive;

(2) the lower oil layer has low extraction degree under the action of steam overburden, and the steam huff and puff is independently carried out on the lower oil layer, so that the lower oil layer can be effectively used, and the extraction degree is improved;

(3) steam is injected into the lower oil layer through the side wells and the corner wells, so that the interlayer can be heated, the steam-driven heat loss of the upper oil layer is reduced, and the fluidity of hot oil around the wells is improved.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present invention, it is to be understood that the orientation or positional relationship indicated by the orientation words such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc. are usually based on the orientation or positional relationship shown in the drawings, and are only for convenience of description and simplicity of description, and in the case of not making a reverse description, these orientation words do not indicate and imply that the device or element being referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore, should not be considered as limiting the scope of the present invention; the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "above … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.

Claims

1. A heavy oil recovery method for a heavy oil reservoir having a barrier (13) between an upper oil layer (11) and a lower oil layer (12) of the heavy oil reservoir, the heavy oil reservoir having an anti-nine-point well group therein, the heavy oil recovery method comprising:

setting packers (30) in a side well (21) and a corner well (22) of the anti-nine well group respectively, wherein the packers (30) are positioned at the position of the isolation layer (13);

-injecting steam through the side wells (21) and corner wells (22) into the lower reservoir (12) for steam stimulation in the lower reservoir (12);

injecting steam into at least the upper reservoir (11) through steam injection wells (23) of the anti-nine well group to perform steam flooding in the upper reservoir (11).

2. A method for recovering thick oil according to claim 1, wherein during the steam injection in said steam injection well (23), said upper oil layer (11) and said lower oil layer (12) each absorb steam.

3. A method for recovering thick oil according to claim 2, wherein the steam is injected into said steam injection well (23) at a rate of 60-70t/d, and the bottom hole dryness of said steam injection well (23) is greater than 70%.

4. The heavy oil recovery method according to claim 1,

the intensity of the injected steam in the lower oil layer (12) is 110-130t/m, and the speed of the injected steam is 60-70 t/d.

5. A method for producing thick oil according to claim 4, characterized in that the bottom hole dryness of the side well (21) and the corner well (22) is more than 70%, and the soaking time of the side well (21) and the corner well (22) is 5-7 days.

6. A method for producing thick oil according to claim 1, characterized in that said packer (30) is a thermal expansion packer (30), said packer (30) being expandable to block said side well (21) and said corner well (22) when said side well (21) and said corner well (22) are injected with steam.

7. A method for thick oil recovery according to claim 6, characterized in that the packer (30) can be retracted to avoid the side well (21) and the corner well (22) without injecting steam into the side well (21) and the corner well (22).

8. A method for thick oil recovery according to claim 1, wherein the side well (21) and the corner well (22) constitute a huff-and-puff well, the method further comprising:

and adjusting injection and production parameters of the steam injection well (23) and the huff-and-puff well until production is finished.

9. The heavy oil recovery method according to claim 1, wherein the heavy oil recovery method is suitable for heavy oil reservoirs after handling multiple rounds.

10. A method for recovering heavy oil according to claim 9, wherein the heavy oil reservoir single well throughput is more than 3 rounds, the upper oil layer (11) of the heavy oil reservoir has been in thermal communication, the thickness of the barrier layer (13) of the heavy oil reservoir is more than 2m, and the difference in permeability of the upper oil layer (11) and the lower oil layer (12) is more than 5.