U.S. patent application number 16/823665 was filed with the patent office on 2021-08-26 for method for injecting non-condensable gas or in-situ combustion to recover remaining oil in a heavy oil reservoir with bottom water.
The applicant listed for this patent is Heavy Oil Development Institute, Liaohe Oilfield Exploration and Development Research Institute, Pet, Southwest Petroleum University. Invention is credited to Changhao HU, Siyuan HUANG, Qi JIANG, Dong WANG, Zhibin WANG, Zhongyuan WANG.
Application Number | 20210262331 16/823665 |
Document ID | / |
Family ID | 1000005764781 |
Filed Date | 2021-08-26 |
United States Patent
Application |
20210262331 |
Kind Code |
A9 |
JIANG; Qi ; et al. |
August 26, 2021 |
METHOD FOR INJECTING NON-CONDENSABLE GAS OR IN-SITU COMBUSTION TO
RECOVER REMAINING OIL IN A HEAVY OIL RESERVOIR WITH BOTTOM
WATER
Abstract
The present invention discloses a method for injecting
non-condensable gas or application of in-situ combustion to recover
remaining oil in a heavy oil reservoir with bottom water,
comprising the following steps: drilling a new horizontal well in
an oil layer between the existing horizontal production well
location and the bottom water layer; preheating the new horizontal
well; after the horizontal section of the horizontal well is in
thermal communication with the upper steam/gas chamber, performing
gas injection in existing wells to maintain pressure slightly
higher or similar to the pressure of the bottom water layer, and
converting the horizontal well into a continuous production well;
drilling a vertical well in the unswept reservoir area;
establishing a fluid communication in the oil layer between the
vertical well and the horizontal well, injecting air or oxygen into
the vertical well; in the later stage of the horizontal well,
stopping gas injection and gradually reducing the pressure in the
steam/gas chamber until the end of oil production. The present
invention produces the remaining oil in the region below the
current horizontal well and near the toe, which greatly improves
the ultimate recovery factor of the oil reservoir.
Inventors: |
JIANG; Qi; (Chengdu, CN)
; HU; Changhao; (Chengdu, CN) ; WANG;
Zhongyuan; (Chengdu, CN) ; HUANG; Siyuan;
(Chengdu, CN) ; WANG; Zhibin; (Chengdu, CN)
; WANG; Dong; (Chengdu, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Southwest Petroleum University
Heavy Oil Development Institute, Liaohe Oilfield Exploration and
Development Research Institute, Pet |
Chengdu
Panjin |
|
CN
CN |
|
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20200300069 A1 |
September 24, 2020 |
|
|
Family ID: |
1000005764781 |
Appl. No.: |
16/823665 |
Filed: |
March 19, 2020 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21B 43/2401 20130101;
E21B 43/168 20130101; E21B 43/24 20130101; E21B 43/243
20130101 |
International
Class: |
E21B 43/243 20060101
E21B043/243; E21B 43/16 20060101 E21B043/16; E21B 43/24 20060101
E21B043/24 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2019 |
CN |
201910205839.1 |
Claims
1. A method for injecting non-condensable gas or application of
in-situ combustion to recover remaining oil in a heavy oil
reservoir with bottom water, comprising the following steps: Step
S10: drilling a new horizontal well in an oil layer between an
existing horizontal production well location and a top of a bottom
water layer; Step S20: preheating the new horizontal well, wherein
during the preheating stage, an operating pressure at a bottom hole
of the new horizontal well is equal to a pressure of the bottom
water layer to prevent an injected fluid from entering the bottom
water layer, including using an original vertical gas injection
well to inject air or flue gas into an existing steam chamber, and
increasing a pressure in the steam chamber to be the same as the
bottom water pressure; Step S30: after a horizontal section of the
new horizontal well is in thermal communication with an upper
steam/gas chamber, converting the new horizontal well into a
continuous production well, including shutting in the original
upper horizontal well when the steam/gas chamber is too low; Step
S40: after an initial stage of the production of the new horizontal
well, drilling a new vertical well in an unswept reservoir area,
wherein the newly drilled vertical well and the new horizontal well
form a new vertical well and new horizontal well combination; Step
S50: after achieving fluid communication in the oil layer between
the new vertical well and the new horizontal well, injecting air or
oxygen into the new vertical well to create a combustion condition
underground, and producing a heated crude oil and combustion gas
from the new horizontal well; and Step S60: when the new horizontal
well enters the later stage, stopping gas injection and gradually
reducing the pressure in the steam/gas chamber until an end of oil
production.
2. The method according to claim 1, wherein the horizontal section
of the horizontal well in the step S10 is placed in the oil layer
having a distance of 2-5 meters above the top of the bottom water
layer.
3. The method according to claim 2, wherein in the step S20,
preheating is performed by any of steam circulation, electric
heating, solvent injecting or the combination thereof.
4. The method according to claim 1, wherein in the step S40, in the
initial stage of the production of a new horizontal well, the
pressure of the steam/gas chamber is higher than the pressure of
the bottom water layer by 300-500 kPa, in order to push the upper
preheated crude oil to the lower horizontal well, and after the
stable production is reached, the pressure in the steam/gas chamber
is controlled at the balanced pressure level of the bottom water
layer.
5. The method according to claim 1, wherein the distance between
the new vertical well and a toe of the new horizontal well is 5-10
meters in the step S40, and the distance between a bottom of a
perforation interval of the new vertical well and the toe level of
the new horizontal well is 3-5 meters.
6. The method according to claim 5, wherein in the step S50, a
fluid communication is established in the oil layer between the new
vertical well and the new horizontal well by any of thermal
circulation, injection of light oil, injection of chemical
solvents, injection of a viscosity reducer, or electric
heating.
7. The method according to claim 6, wherein the pressure of the new
horizontal well is kept equal to the pressure of the bottom water
layer during the entire fluid communication process, reducing the
risk of bottom water invading a production well and the steam/gas
chamber.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method for injecting
non-condensable gas or in-situ combustion to recover remaining oil
in a heavy oil reservoir with bottom water.
BACKGROUND
[0002] The type of heavy oil reservoirs with bottom water is very
common. At present, most of the heavy oil reservoirs that carry out
steam injection thermal recovery in Liaohe Oilfield are medium-deep
buried with thick bottom water (as shown in FIG. 1). The red colour
in the figure is an oil layer, and the blue section is a water
layer. In these reservoirs, a vertical well steam huff and puff
producing method is mainly used. Some reservoirs have also switched
to a steam flooding or steam-assisted gravity drainage (SAGD)
producing method in the later stage of steam huff and puff. Steam
huff and puff relies on the steam injected into the near-well zone
to heat the oil layer, to reduce the viscosity of the crude oil,
and then lift the mixture of crude oil and steam condensate to the
ground. When the formation temperature decreases to the point where
the oil production cannot reach economic production, a steam slug
is injected into the formation. When the pressure and temperature
in the near-well zone increase, the well is opened for production.
This production process is repeatedly applied for multiple cycles
until the cycle production effect is below the economic limit. With
the progress of the production process, the pressure of the
producing layer decreases with the huff and puff cycle. Because the
pressure of the bottom water layer is high, due to the pressure
difference between the bottom water layer and the production layer,
the bottom water tends to flow upward. Once the bottom water breaks
into the production intervals, the thermal efficiency from steam
injection will be greatly reduced. In severe cases, production
wells will be shut down and the development efficiency of the
entire reservoir will be affected. In order to prevent or avoid the
bottom water from breaking into the production well prematurely, a
part of the oil layer thickness (10-20 meters) is generally
reserved in the lower part of the reservoir as a barrier for
preventing the bottom water from coming into the production
interval. Therefore, at the end of the development of the huff and
puff, a considerable proportion of the unused oil layer will be
left above the bottom water layer.
SUMMARY
[0003] The present invention mainly overcomes the shortcomings in
the prior art, and proposes a method for injecting non-condensable
gas or application of in-situ combustion to recover remaining oil
in a heavy oil reservoir with bottom water.
[0004] The technical solution provided by the present invention for
solving the above technical problems is: a method for injecting
non-condensable gas or in-situ combustion to recover remaining oil
in a heavy oil reservoir with bottom water, comprising the
following steps:
[0005] Step S10: drilling a new horizontal well in an oil layer
between the existing horizontal production well location and the
top of bottom water layer;
[0006] Step S20: preheating the new horizontal well, wherein during
the preheating stage, the operating pressure at the bottom hole of
the new horizontal well is equal to the pressure of the water layer
to prevent the injected fluid from entering the bottom water layer;
meanwhile, using the original vertical gas injection well to inject
air or flue gas into the existing steam chamber, and increasing the
pressure in the steam chamber to the same as the bottom water
pressure;
[0007] Step S30: after the horizontal section of the new horizontal
well is in thermal communication with the upper steam/gas chamber,
convert the new horizontal well into a continuous production well;
shutting in the original upper horizontal well when steam/gas
chamber is too low;
[0008] Step S40: after the initial stage of the production of the
new horizontal well, drilling a new vertical well in the unswept
reservoir area, wherein the newly drilled vertical well and the new
horizontal well form a new pair of vertical well and horizontal
well combination;
[0009] Step S50: after achieving fluid communication in the oil
layer between the new vertical well and the new horizontal well,
injecting air or oxygen into the vertical well to create combustion
condition underground, and producing the heated crude oil and
combustion gas from the new horizontal well;
[0010] Step S60: when the horizontal well enters the later stage,
stopping gas injection and gradually reducing the pressure in the
gas chamber until the end of oil production.
[0011] A further technical solution is that the horizontal section
of the horizontal well in step S10 is placed in the oil layer
having a distance of 2-5 meters above the top of the bottom water
layer.
[0012] A further technical solution is that in step S20, preheating
is performed by any of steam circulation, electric heating, solvent
injecting, or the combination thereof.
[0013] A further technical solution is that in the step S40, in the
initial stage of the production of a new horizontal well, the
pressure of the gas chamber is higher than the pressure of the
bottom water layer by 300-500 kPa, in order to push the upper
preheated crude oil to the lower horizontal well. And after the
stable production is reached, the pressure in the steam/gas chamber
is controlled at the balanced pressure level of the bottom water
layer.
[0014] A further technical solution is that the distance between
the vertical well and the toe of the horizontal well is 5-10 meters
in the step S40, and the distance between the bottom boundary of
the perforation interval of the vertical well and the toe level of
the horizontal well is 3-5 meters.
[0015] A further technical solution is that in the step S50, a
fluid communication is established in the oil layer between the
vertical well and the horizontal well by any means of thermal
circulation, injection of light oil, injection of chemical
solvents, injection of a viscosity reducer, or electric
heating.
[0016] A further technical solution is that the pressure of the
horizontal well is kept equal to the pressure of the bottom water
layer during the entire fluid communication process, reducing the
risk of bottom water invading a production well and a gas
chamber.
[0017] The present invention has the following advantages: the
present invention produces the remaining oil below the current
horizontal well and near the toe, which greatly improves the
ultimate recovery of heavy oil reservoirs with strong bottom
water.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a vertical cross-section diagram of a medium-deep
heavy oil reservoir with bottom water in Liaohe Oilfield;
[0019] FIG. 2 is a schematic diagram of the remaining oil
distribution in a combined gravity drainage production method of a
vertical well and a horizontal well in a bottom water
reservoir;
[0020] FIG. 3 is a schematic diagram of producing remaining oil in
a bottom water reservoir using a combination of original vertical
well injection of non-condensable gas and new horizontal well;
[0021] FIG. 4 is a schematic diagram of producing remaining oil in
a bottom water reservoir using a newly drilled vertical well or a
combination of an old well and a new horizontal well to conduct air
injection (initial stage of production);
[0022] FIG. 5 is a schematic diagram of producing remaining oil in
a bottom water reservoir using a newly drilled vertical well or a
combination of an old well and a new horizontal well to conduct air
injection (later stage of production).
DESCRIPTION OF THE EMBODIMENTS
[0023] The present invention will be further described below with
reference to the embodiments and the accompanying drawings.
Embodiment 1
[0024] As shown in FIGS. 2-5, the method for injecting
non-condensable gas or application of in-situ combustion to recover
remaining oil in a heavy oil reservoir with bottom water according
to the present invention comprises the following steps:
[0025] (1) drilling a new horizontal well in an oil layer between
the existing horizontal production well location and the bottom
water layer, wherein the horizontal well is located in the oil
layer having a distance of 2-5 meters above the top of the bottom
water layer;
[0026] (2) preheating the new horizontal well by any of steam
circulation, electric heating, solvent injecting or the combination
thereof, wherein during the preheating stage, the operating
pressure at the bottom of the well is equal to the pressure of the
water layer to prevent the injected fluid from entering the bottom
water layer; meanwhile, using the original vertical gas injection
well to inject air or flue gas into the steam/gas chamber, and
increasing the pressure in the steam/gas chamber to the same as the
bottom water pressure;
[0027] (3) after the horizontal section of the new horizontal well
is in thermal communication with the upper steam/gas chamber,
converting the new horizontal well into a continuous production
well; shutting in the original upper horizontal well when steam/gas
chamber is too low.
[0028] wherein in the initial stage of the production of a
horizontal well (as shown in FIG. 4), the pressure of the steam/gas
chamber is controlled within the range higher than the pressure of
the bottom water layer by 300-500 kPa, in order to push the upper
preheated crude oil to the lower horizontal well, and after the
stable production is reached, the pressure in the steam/gas chamber
is controlled at the balanced pressure level of the bottom water
layer.
[0029] (4) after the initial stage of the production of the new
horizontal well, drilling a new vertical well in the unswept
reservoir area, wherein the newly drilled vertical well and the new
horizontal well form a new pair of vertical well and horizontal
well combination; the distance between the bottom boundary of the
perforation well section of the vertical well and the toe level of
the horizontal well is 3-5 meters.
[0030] (5) forming a fluid communication in the oil layer between
the vertical well and the horizontal well by any means of thermal
circulation, injection of light oil, injection of chemical
solvents, injection of a viscosity reducer, or electric heating,
wherein the pressure of the horizontal well is kept equal to the
pressure of the bottom water layer during the entire fluid
communication process, reducing the risk of bottom water invading a
production well and a steam/gas chamber;
[0031] after the injection and production well forms the
communication, injecting air or oxygen into the vertical well,
forming the condition for in-situ combustion underground, and
producing the heated crude oil and combustion gas from the
horizontal well, wherein with the progress of the production
process, the steam/gas chamber further expands in the reservoir
along the new horizontal well and the vertical well, and produces
the remaining oil in the lower part of the crude oil above the new
horizontal well and near the toe (as shown in FIG. 5), which
greatly improves the ultimate recovery of the oil reservoir;
[0032] during the above entire process, the combustion gas
generated underground enters the upper steam/gas chamber, which
will help increase the pressure in the steam/gas chamber and
prevent the bottom water from advancing upward; once the fluid is
injected or the horizontal well communicates with the original
steam/gas chamber, the upper horizontal well is shut down;
[0033] (6) when the horizontal well enters the later stage,
stopping gas injection and gradually reducing the pressure in the
steam/gas chamber until the end of oil production, wherein due to
the high energy of the bottom water layer, due to being driven by
the pressure difference between the bottom water layer and the
steam/gas chamber, the heated crude oil in the lower part of the
horizontal well will be displaced to the production well for
production, further increasing the recoverable reserves of the oil
layer.
[0034] In the present embodiment, there are the initial stage of
horizontal well production, the middle stage of the horizontal well
production, and the later stage of the horizontal well
production.
[0035] The initial stage of horizontal well production refers to
the period between the time when a newly drilled horizontal well is
put into production and the time when the horizontal well cannot be
economically produced.
[0036] The middle stage of the horizontal well production refers to
the period between the time when a new vertical well is drilled and
the horizontal well is re-open for production and the time when the
re-produced horizontal well produces the crude oil in the upper
part of the horizontal well to the economic limit after the
horizontal well cannot be economically developed.
[0037] The later stage of the horizontal well production refers to
the period between the time when the re-produced horizontal well
produces the crude oil in the upper part of the horizontal well to
the economic limit and the time when the oil production ends.
[0038] The application range of the present embodiment is the heavy
oil reservoir with bottom water and
[0039] (1) an oil layer of more than 10 meters is left behind below
the SAGD horizontal production well;
[0040] (2) an oil layer of more than 10 meters is left behind below
the bottom of perforation interval from vertical well steam huff
and puff;
[0041] (3) Due to the geological structure, there is an oil
reservoir with a lot of remaining oil left behind below the
horizontal production well.
[0042] The above description does not limit the present invention
in any form. Although the present invention has been disclosed
through the above embodiments, it is not intended to limit the
present invention. Any person skilled in the art can use the above
disclosed technical content to make some changes or modifications
to equivalent embodiments without departing from the scope of the
technical solution of the present invention. As long as the content
does not depart from the technical solution of the present
invention, any simple modification, equivalent changes, and
modifications made to the above embodiments are based on the
technical essence of the present invention still falling within the
scope of the technical solution of the present invention.
* * * * *