CA2330094C - Steam-assisted gravity drainage process - Google Patents
Steam-assisted gravity drainage process Download PDFInfo
- Publication number
- CA2330094C CA2330094C CA 2330094 CA2330094A CA2330094C CA 2330094 C CA2330094 C CA 2330094C CA 2330094 CA2330094 CA 2330094 CA 2330094 A CA2330094 A CA 2330094A CA 2330094 C CA2330094 C CA 2330094C
- Authority
- CA
- Canada
- Prior art keywords
- steam
- reservoir
- oil
- injection
- well
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000010796 Steam-assisted gravity drainage Methods 0.000 title claims abstract description 28
- 238000000034 method Methods 0.000 title claims description 17
- 230000008569 process Effects 0.000 title claims description 17
- 238000004519 manufacturing process Methods 0.000 claims abstract description 41
- 238000002347 injection Methods 0.000 claims abstract description 17
- 239000007924 injection Substances 0.000 claims abstract description 17
- 238000010793 Steam injection (oil industry) Methods 0.000 claims abstract description 12
- 238000005086 pumping Methods 0.000 claims abstract description 8
- 239000003921 oil Substances 0.000 claims description 32
- 239000000295 fuel oil Substances 0.000 claims description 3
- 230000000149 penetrating effect Effects 0.000 claims description 3
- 239000012530 fluid Substances 0.000 abstract description 8
- 238000011065 in-situ storage Methods 0.000 abstract description 4
- 230000009467 reduction Effects 0.000 abstract description 2
- 238000011084 recovery Methods 0.000 abstract 1
- 230000004907 flux Effects 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000008859 change Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007717 exclusion Effects 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- SRVJKTDHMYAMHA-WUXMJOGZSA-N thioacetazone Chemical compound CC(=O)NC1=CC=C(\C=N\NC(N)=S)C=C1 SRVJKTDHMYAMHA-WUXMJOGZSA-N 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK 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
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
- E21B43/2406—Steam assisted gravity drainage [SAGD]
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Geology (AREA)
- Mining & Mineral Resources (AREA)
- Physics & Mathematics (AREA)
- Environmental & Geological Engineering (AREA)
- Fluid Mechanics (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Production Of Liquid Hydrocarbon Mixture For Refining Petroleum (AREA)
- Engine Equipment That Uses Special Cycles (AREA)
Abstract
Following second phase steam assisted gravity drainage operation using a co-operating pair of steam injection and fluid production wells, ste am injection is terminated while flowing fluid production is continued, to draw down the reservoir pressure and flash steam in situ. Then a downhole pump is actuated to produce reservoir fluid and further reduce the reservoir pressure; thereby generating additional steam in situ. As a result of these steps, an additional recovery of oil is realized, using residual heat remaining in the reservoir at the end of steam injection and incremental steam generated in situ by pressure reduction obtained by pumping.
Description
2 "Steam-assisted gravity drainage" and "SAGD" are a phrase and
3 acronym used to identify a known oilfield thermal process. This SAGD
4 process is now being used in Western Canada to recover heavy oil from shallow subterranean reservoirs.
6 The SAGD process typically involves:
7 ~ Providing a number of parallel co-operating pairs of horizontal wells 8 located at spaced points across the reservoir. The wells are 9 positioned close to the reservoir base (see Figure 1 );
~ Each co-operating pair comprises an upper injection well and a 11 lower production well. The wells usually extend co-extensively, in 12 parallel, with the injection well located directly above the production 13 well in closely spaced relationship;
14 ~ The wells are suitably equipped for thermal operation;
~ In the first phase of the process, fluid transmissibility is established 16 between the wells of each pair. For example, steam may bas 17 circulated down to the toe of each well through a production tubin~~
18 string and back through the annulus formed between the production 19 tubing and the string comprising a sand exclusion liner and production casing. In effect; circulation of steam through the two 21 wells creates two "hot fingers" which conductively heat the span of 22 formation extending between the wells. Circulation of steam is 23 continued until the viscosity of the oil in the span is sufficiently 24 reduced so that it can be displacE;d or driven. Pressure dififerential 1 between the injection and production wells is then used to flush or 2 drive the oil in the span into the production well, through which it is 3 produced;
4 ~ In the second phase of the process, the injection well is dedicated to injecting steam and the production well is dedicated to producing 6 fluid. As steam is injected into the formation through the injection 7 well, it rises, contacts and heats cold oil and the heated oil drains., 8 along with steam condensate, down to the production well and is 9 produced. Gradually an upwardly and outwardly developing stearn chamber is formed. See Figure 2. The oil originally in the chamber 11 has drained and been produced. The chamber pores are now filled 12 with steam. Newly injected steam rises to the boundary surface of 13 the chamber, heats cold oil at the boundary and continues the 14 gradual expansion of the chamber. As shown in Figure 1, the chamber continues growing upwardly and outwardly, with .a 16 generally conical cross-section, until it reaches the overburden 17 overlying the reservoir and contacts an adjacent steam chamber.
18 The process is usually terminated when the operation becomes 19 uneconomic due to ineffective heating and declining oil production;
~ It needs to be understood that the SAGD oil production is of a 21 flowing nature. Downhole pumps are generally not used during the 22 second phase of the SAGD process.
1 The present invention is concerned with alleviating a problem 2 associated with the SAGD process. More particularly, a large amount of 3 energy or heat is retained in the steam chamber when the process becomes 4 mature. This is illustrated in Figure 3. It is therefore the objective of the present invention to provide a post-SAGD step to recover some of the energy 6 remaining at the end of the process for the production of oil.
9 At the conclusion of the second phase of the SAGD process, the steam chamber is under pressure and at high temperature. Example conditions 11 might be a temperature of 263°C and a pressure of 5000 kPa.
12 Following the second phase, in accordance with the invention:
13 ~ steam injection is terminated while flowing production is continued, 14 to lower the reservoir pressure ~ a downhole pump is then positioned in the production well - the 16 pump is operable from ground surface in conventional fashion;
17 ~ the pump is actuated to produce fluid from the production well and 18 draw down the pressure in the reservoir;
19 ~ as a result of the pressure draw-down, liquid water in the reservoir will evaporate as the pressure is reduced - this in situ-produced 21 "new" steam will function to heat cold oil at the steam chamber 22 boundary. In addition, residual heat in the chamber will also act to 23 warm and mobilize some of the reservoir oil.
1 In one embodiment, the invention is concerned with a process for recovering heavy 2 oil from an underground reservoir comprising: providing a production well and an injection 3 well, both wells horizontally penetrating the reservoir, the wells being generally parallel and 4 co-extensive, the injection well being spaced above the production well, so that the pair of wells are capable of cooperating in the practice of steam assisted gravity drainage; practicing 6 steam assisted gravity drainage production of oil from the reservoir on a flowing basis by 7 injecting steam into the reservoir through the injection well to enlarge a steam chamber and $ heat reservoir oil so that it drains into and is produced through the production well; then 9 terminating steam injection; inserting a downhole pump in the production well; and actuating the pump to produce oil on a pumping basis from the reservoir and reduce the steam chamber 11 pressure.
. 4a - ; 83126010.DOC;1 f 2 Figure 1 is a fanciful side view showing adjoining mature steam 3 chambers in contact with each other and the overburden, said chambers 4 having been created by two pairs of co-operating SAGD wells;
Figure 2 is a fanciful end view showing a steam chamber with a pair of 6 co-operating SAGD wells;
7 Figure 3 is a representation of data from a numerical modelling run 8 during second phase SAGD, illustrating the temperature isotherms produced 9 in connection with a steam chamber, together with the flux of steam (represented by the cross-hatching); and 11 Figure 4 is a representation of data from the numerical modelling run 12 after one-half year of post-SAGD pumping, illustrating the temperature 13 isotherms produced, together with the flux of steam.
DESCRIPTION OF THE PREFERRED EMBODIMENT
16 The invention is an improvement on a conventional steam-assisted 17 gravity drainage process wherein, in a first phase, fluid communication is 18 established between a co-operating pair of upper injection and lower 19 production horizontal wells positioned in a reservoir containing cold oil and water, and, in a second phase, steam is injected through the injection well and 21 heated oil and steam condensate are produced through the production well, 22 thereby developing a steam chamber having elevated temperature and 23 pressure. The improvement comprises: terminating steam injection while 24 continuing to produce the production well under flowina condition, thereby G
1 reducing reservoir pressure; positioning a downhole pump in the production 2 well and actuating the pump to produce fluid from the reservoir, thereby 3 further reducing the steam chamber pressure, so that water in the reservoir 4 evaporates and produces steam in situ to further heat cold oil in the reservoir and render it producible.
6 The utility of the described process is demonstrated by the following 7 results from a numerical modelling run incorporating the invention:
8 ~ Amounts of oil production and steam injection over a 4 year term of 9 second phase SAGD, were:
oil production 291,770 m3 11 steam injection 757,420 m3 12 steam:oil ratio 2.60 13 ~ Amounts of additional oil production and steam injection obtained 14 by continuing the run during 418 days of pumping post-SAGD:
oil production 67,380 m3 16 steam injection 0 17 overall steam:oil ratio 2.11.
18 From the foregoing, it will be noted that substantial additional oil can be 19 recovered without steam injection, using the residual energy present in the steam chamber after SAGD, when coupled with mechanical pumping.
21 Pumping functions to reduce the steam chamber pressure. The run 22 demonstrates a consequent reduction in the overall steam ratio.
1 The predicted isotherm and steam flux results of the numerical 2 modelling run are illustrated in Figure 4 for a half year period. The steam 3 chamber is cooled from 263°C to 215°C. This change in temperature 4 corresponds to about 20% chamber residual energy utilization. It is predicted that up to 40% of the residual energy can be utilized.
6 The timing for switching from second phase SAGD to the post-SAGD is 7 dependent on the maturity or completeness of second phase SAGD. The 8 optimum timing can be determined by a numerical simulation study. Usually it 9 will occur after 2 to 6 years of second stage SAGD operation.
6 The SAGD process typically involves:
7 ~ Providing a number of parallel co-operating pairs of horizontal wells 8 located at spaced points across the reservoir. The wells are 9 positioned close to the reservoir base (see Figure 1 );
~ Each co-operating pair comprises an upper injection well and a 11 lower production well. The wells usually extend co-extensively, in 12 parallel, with the injection well located directly above the production 13 well in closely spaced relationship;
14 ~ The wells are suitably equipped for thermal operation;
~ In the first phase of the process, fluid transmissibility is established 16 between the wells of each pair. For example, steam may bas 17 circulated down to the toe of each well through a production tubin~~
18 string and back through the annulus formed between the production 19 tubing and the string comprising a sand exclusion liner and production casing. In effect; circulation of steam through the two 21 wells creates two "hot fingers" which conductively heat the span of 22 formation extending between the wells. Circulation of steam is 23 continued until the viscosity of the oil in the span is sufficiently 24 reduced so that it can be displacE;d or driven. Pressure dififerential 1 between the injection and production wells is then used to flush or 2 drive the oil in the span into the production well, through which it is 3 produced;
4 ~ In the second phase of the process, the injection well is dedicated to injecting steam and the production well is dedicated to producing 6 fluid. As steam is injected into the formation through the injection 7 well, it rises, contacts and heats cold oil and the heated oil drains., 8 along with steam condensate, down to the production well and is 9 produced. Gradually an upwardly and outwardly developing stearn chamber is formed. See Figure 2. The oil originally in the chamber 11 has drained and been produced. The chamber pores are now filled 12 with steam. Newly injected steam rises to the boundary surface of 13 the chamber, heats cold oil at the boundary and continues the 14 gradual expansion of the chamber. As shown in Figure 1, the chamber continues growing upwardly and outwardly, with .a 16 generally conical cross-section, until it reaches the overburden 17 overlying the reservoir and contacts an adjacent steam chamber.
18 The process is usually terminated when the operation becomes 19 uneconomic due to ineffective heating and declining oil production;
~ It needs to be understood that the SAGD oil production is of a 21 flowing nature. Downhole pumps are generally not used during the 22 second phase of the SAGD process.
1 The present invention is concerned with alleviating a problem 2 associated with the SAGD process. More particularly, a large amount of 3 energy or heat is retained in the steam chamber when the process becomes 4 mature. This is illustrated in Figure 3. It is therefore the objective of the present invention to provide a post-SAGD step to recover some of the energy 6 remaining at the end of the process for the production of oil.
9 At the conclusion of the second phase of the SAGD process, the steam chamber is under pressure and at high temperature. Example conditions 11 might be a temperature of 263°C and a pressure of 5000 kPa.
12 Following the second phase, in accordance with the invention:
13 ~ steam injection is terminated while flowing production is continued, 14 to lower the reservoir pressure ~ a downhole pump is then positioned in the production well - the 16 pump is operable from ground surface in conventional fashion;
17 ~ the pump is actuated to produce fluid from the production well and 18 draw down the pressure in the reservoir;
19 ~ as a result of the pressure draw-down, liquid water in the reservoir will evaporate as the pressure is reduced - this in situ-produced 21 "new" steam will function to heat cold oil at the steam chamber 22 boundary. In addition, residual heat in the chamber will also act to 23 warm and mobilize some of the reservoir oil.
1 In one embodiment, the invention is concerned with a process for recovering heavy 2 oil from an underground reservoir comprising: providing a production well and an injection 3 well, both wells horizontally penetrating the reservoir, the wells being generally parallel and 4 co-extensive, the injection well being spaced above the production well, so that the pair of wells are capable of cooperating in the practice of steam assisted gravity drainage; practicing 6 steam assisted gravity drainage production of oil from the reservoir on a flowing basis by 7 injecting steam into the reservoir through the injection well to enlarge a steam chamber and $ heat reservoir oil so that it drains into and is produced through the production well; then 9 terminating steam injection; inserting a downhole pump in the production well; and actuating the pump to produce oil on a pumping basis from the reservoir and reduce the steam chamber 11 pressure.
. 4a - ; 83126010.DOC;1 f 2 Figure 1 is a fanciful side view showing adjoining mature steam 3 chambers in contact with each other and the overburden, said chambers 4 having been created by two pairs of co-operating SAGD wells;
Figure 2 is a fanciful end view showing a steam chamber with a pair of 6 co-operating SAGD wells;
7 Figure 3 is a representation of data from a numerical modelling run 8 during second phase SAGD, illustrating the temperature isotherms produced 9 in connection with a steam chamber, together with the flux of steam (represented by the cross-hatching); and 11 Figure 4 is a representation of data from the numerical modelling run 12 after one-half year of post-SAGD pumping, illustrating the temperature 13 isotherms produced, together with the flux of steam.
DESCRIPTION OF THE PREFERRED EMBODIMENT
16 The invention is an improvement on a conventional steam-assisted 17 gravity drainage process wherein, in a first phase, fluid communication is 18 established between a co-operating pair of upper injection and lower 19 production horizontal wells positioned in a reservoir containing cold oil and water, and, in a second phase, steam is injected through the injection well and 21 heated oil and steam condensate are produced through the production well, 22 thereby developing a steam chamber having elevated temperature and 23 pressure. The improvement comprises: terminating steam injection while 24 continuing to produce the production well under flowina condition, thereby G
1 reducing reservoir pressure; positioning a downhole pump in the production 2 well and actuating the pump to produce fluid from the reservoir, thereby 3 further reducing the steam chamber pressure, so that water in the reservoir 4 evaporates and produces steam in situ to further heat cold oil in the reservoir and render it producible.
6 The utility of the described process is demonstrated by the following 7 results from a numerical modelling run incorporating the invention:
8 ~ Amounts of oil production and steam injection over a 4 year term of 9 second phase SAGD, were:
oil production 291,770 m3 11 steam injection 757,420 m3 12 steam:oil ratio 2.60 13 ~ Amounts of additional oil production and steam injection obtained 14 by continuing the run during 418 days of pumping post-SAGD:
oil production 67,380 m3 16 steam injection 0 17 overall steam:oil ratio 2.11.
18 From the foregoing, it will be noted that substantial additional oil can be 19 recovered without steam injection, using the residual energy present in the steam chamber after SAGD, when coupled with mechanical pumping.
21 Pumping functions to reduce the steam chamber pressure. The run 22 demonstrates a consequent reduction in the overall steam ratio.
1 The predicted isotherm and steam flux results of the numerical 2 modelling run are illustrated in Figure 4 for a half year period. The steam 3 chamber is cooled from 263°C to 215°C. This change in temperature 4 corresponds to about 20% chamber residual energy utilization. It is predicted that up to 40% of the residual energy can be utilized.
6 The timing for switching from second phase SAGD to the post-SAGD is 7 dependent on the maturity or completeness of second phase SAGD. The 8 optimum timing can be determined by a numerical simulation study. Usually it 9 will occur after 2 to 6 years of second stage SAGD operation.
Claims (2)
1. A process for recovering heavy oil from an underground reservoir comprising:
providing a production well and an injection well, both wells horizontally penetrating the reservoir, the wells being generally parallel and co-extensive, the injection well being spaced above the production well, so that the pair of wells are capable of cooperating in the practice of steam assisted gravity drainage;
practicing steam assisted gravity drainage production of oil from the reservoir on a flowing basis by injecting steam into the reservoir through the injection well to enlarge a steam chamber and heat reservoir oil so that it drains into and is produced through the production well;
then terminating steam injection;
inserting a downhole pump in the production well; and actuating the pump to produce oil on a pumping basis from the reservoir and reduce the steam chamber pressure.
providing a production well and an injection well, both wells horizontally penetrating the reservoir, the wells being generally parallel and co-extensive, the injection well being spaced above the production well, so that the pair of wells are capable of cooperating in the practice of steam assisted gravity drainage;
practicing steam assisted gravity drainage production of oil from the reservoir on a flowing basis by injecting steam into the reservoir through the injection well to enlarge a steam chamber and heat reservoir oil so that it drains into and is produced through the production well;
then terminating steam injection;
inserting a downhole pump in the production well; and actuating the pump to produce oil on a pumping basis from the reservoir and reduce the steam chamber pressure.
2. A process for recovering heavy oil from an underground reservoir comprising:
providing a production well and an injection well, both wells horizontally penetrating the reservoir, the wells being generally parallel and co-extensive, the injection well being spaced above the production well, so that the pair of wells are capable of cooperating in the practice of steam assisted gravity drainage;
practicing steam assisted gravity drainage production of oil from the reservoir on a flowing basis by injecting steam into the reservoir through the injection well to enlarge a steam chamber and heat reservoir oil so that it drains into and is produced through the production well;
terminating steam injection;
continuing to produce oil from the reservoir by flowing it through the production well for a predetermined period; and then inserting a downhole pump in the production well; and actuating the pump to produce oil on a pumping basis from the reservoir and reduce the steam chamber pressure.
providing a production well and an injection well, both wells horizontally penetrating the reservoir, the wells being generally parallel and co-extensive, the injection well being spaced above the production well, so that the pair of wells are capable of cooperating in the practice of steam assisted gravity drainage;
practicing steam assisted gravity drainage production of oil from the reservoir on a flowing basis by injecting steam into the reservoir through the injection well to enlarge a steam chamber and heat reservoir oil so that it drains into and is produced through the production well;
terminating steam injection;
continuing to produce oil from the reservoir by flowing it through the production well for a predetermined period; and then inserting a downhole pump in the production well; and actuating the pump to produce oil on a pumping basis from the reservoir and reduce the steam chamber pressure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2330094 CA2330094C (en) | 2001-01-03 | 2001-01-03 | Steam-assisted gravity drainage process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2330094 CA2330094C (en) | 2001-01-03 | 2001-01-03 | Steam-assisted gravity drainage process |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2330094A1 CA2330094A1 (en) | 2002-07-03 |
| CA2330094C true CA2330094C (en) | 2006-04-18 |
Family
ID=4168027
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2330094 Expired - Lifetime CA2330094C (en) | 2001-01-03 | 2001-01-03 | Steam-assisted gravity drainage process |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2330094C (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2631977C (en) | 2008-05-22 | 2009-06-16 | Gokhan Coskuner | In situ thermal process for recovering oil from oil sands |
| CN119177834B (en) * | 2023-06-21 | 2025-10-28 | 中国石油天然气股份有限公司 | Methods, applications, media and equipment for distinguishing oil layer production status in bottom water heavy oil reservoirs developed by SAGD |
-
2001
- 2001-01-03 CA CA 2330094 patent/CA2330094C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| CA2330094A1 (en) | 2002-07-03 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5931230A (en) | Visicous oil recovery using steam in horizontal well | |
| CA2228416C (en) | Enhanced lift method and apparatus for the production of hydrocarbons | |
| US5215146A (en) | Method for reducing startup time during a steam assisted gravity drainage process in parallel horizontal wells | |
| CN102852496B (en) | A method for producing medium-deep heavy oil reservoirs | |
| CA2697417C (en) | A method for accelerating start-up for steam assisted gravity drainage operations | |
| US7090014B2 (en) | Process for sequentially applying SAGD to adjacent sections of a petroleum reservoir | |
| US3396791A (en) | Steam drive for incompetent tar sands | |
| CA2871568C (en) | Waste heat recovery from depleted reservoir | |
| CA2251157C (en) | Process for sequentially applying sagd to adjacent sections of a petroleum reservoir | |
| US3682244A (en) | Control of a steam zone | |
| RU2232263C2 (en) | Method for extracting of high-viscosity oil | |
| RU2168619C1 (en) | Method of heat treatment of bottom-hole zone of oil-gas well | |
| CA2898065C (en) | Pressure cycling with mobilizing fluid circulation for heavy hydrocarbon recovery | |
| CA2330094C (en) | Steam-assisted gravity drainage process | |
| US12497877B2 (en) | End-of-life recovery of mobilized hydrocarbons | |
| CA1310581C (en) | Method of improving the areal sweep efficiency of a steam flood oil recovery process | |
| US20120318512A1 (en) | Thermally assisted gravity drainage (tagd) | |
| CA2277378C (en) | Steam-assisted gravity drainage heavy oil recovery process | |
| CA2313837C (en) | Positioning of the tubing string in a steam injection well | |
| Bursell | Steam DisplacementKern River Field | |
| CA2888892C (en) | Non condensing gas management in sagd | |
| RU2307242C1 (en) | High-viscosity oil production method | |
| CN107514250B (en) | A method for steam-assisted gravity drainage | |
| CA2962036C (en) | Heel to toe thermal hydrocarbon recovery | |
| CA2889447C (en) | Cooperative multidirectional fluid injection and enhanced drainage length in thermal recovery of heavy oil |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKEX | Expiry |
Effective date: 20210104 |