CA1259562A - Modified 7 spot patterns of horizontal and vertical wells for improving oil recovery efficiency - Google Patents
Modified 7 spot patterns of horizontal and vertical wells for improving oil recovery efficiencyInfo
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- CA1259562A CA1259562A CA000533299A CA533299A CA1259562A CA 1259562 A CA1259562 A CA 1259562A CA 000533299 A CA000533299 A CA 000533299A CA 533299 A CA533299 A CA 533299A CA 1259562 A CA1259562 A CA 1259562A
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Abstract
VERTICAL WELLS FOR IMPROVING OIL RECOVERY EFFICIENCY
ABSTRACT
The invention is a method of recovering hydrocarbons from an underground formation by employing modified 7 spot well patterns which contain six substantially vertical corner wells forming a substantially hexagonal well pattern and six substantially horizontal wells located within the hexagonal well pattern running between each of the vertical corner wells and the center of the well pattern. Preferably, the modified 7 spot pattern will also contain a substantially vertical central well located relatively near the center of the substantially hexagonal well pattern. Another embodiment contains six substantially vertical corner wells forming a substantially hexagonal well pattern, a substantially vertical central well and six sets of three horizontal wells, each set of three horizontal wells forming a substantially Y-shaped pattern.
ABSTRACT
The invention is a method of recovering hydrocarbons from an underground formation by employing modified 7 spot well patterns which contain six substantially vertical corner wells forming a substantially hexagonal well pattern and six substantially horizontal wells located within the hexagonal well pattern running between each of the vertical corner wells and the center of the well pattern. Preferably, the modified 7 spot pattern will also contain a substantially vertical central well located relatively near the center of the substantially hexagonal well pattern. Another embodiment contains six substantially vertical corner wells forming a substantially hexagonal well pattern, a substantially vertical central well and six sets of three horizontal wells, each set of three horizontal wells forming a substantially Y-shaped pattern.
Description
~zs~s~
MODIFIF,~ 7 SPOl' PATTERNS OF HORIZONT~L AND
VERTICAL WELL~ FOR ~MPROVING OIL RECOVERY ~FFICIENCY
(D#78,595-l~F) B~CKG~OUND OF TI~E INVENTION
The inven-tion process is concerned with the enhanced recovery of oil from underground formations. More particularly, the invention relates to a method for recovering hydrocarbons with modified 7 spot well patterns employing horizontal wells placed between vertical wells.
Horizontal wel]s have been investigated and tested for oil recovery for quite some time. Although horizontal wells may in the future be proven economically successful to recover petroleum from many types of formations, at present, the use of horizontal wells is usually limited to formations containing highly viscous crude. It seems likely that horizontal wells will soon become a chief method of producing tar sand formations and other highly viscous oils which cannot be efficiently produced by conventional methods because of their high viscosity.
Various proposals have been set forth for petroleum recovery with horizontal well schemes. Most have involved steam injection or in situ combustion with horizontal wells serving as both injection wells and produci.ng wells~ Steam and combustion processes have been employed to heat viscous formati.ons to lower the viscosity of the petroleum as well as to provide the driving force to push the hydrocarbons toward a well.
~Z5~ Z
U~ S. Patent No. 4,~83,088 illustrates the use of a system of radial horiæontal wells, optionally in conjunction with an inverted 9 spot having an unsually l.arge number of injection wells. U. S. Patent No~ 4,390,0~7 illustrates a scheme of using horizontal and vertical wel.ls together to form a pentagonal shaped pattern which is labeled a ~'5 spot" in the patent, al-though the ar~ recognizes a different pattern as constituting a 5 spot.
S~MMARY OF THE INVENTION
The invention is a method of recovering hydrocarbons from an underground formation by employing modified 7 spot well patterns. The patterns contain six substantially vertical corner wells forming a substantially hexagonal well pattern and six substantially horizontal wells located within the hexagonal well pattern running like the spokes of a wheel between each of the vertical corner wells and the center of the well pattern.
Preferably, the modified 7 spot pattern will also contain a substantially vertical central well located relatively near the center of the substantially hexagonal well pattern.
An alternate elnbodiment conta:ins d second set of six substantially horizon-tal. wells. E.ach of the additional six horizontal wells is located between the corner wells, each horizontal well having one end located re]atively near a vertical ~2~9S62 corner well and the other end located relatively near an adjacent vertical corner well.
A third embodlment contains a distinctly different combination of horizontal wells with the vertical wells of the 7 spot pattern. This pattern contains six substantial]y vertical corner wells forming a substantially hexagonal well pattern, a substantially vertical central well and six sets of three hori zontal wells. Each set of three horizontal wells forms a sub-stantially Y-shaped pattern wherein one of the three ends of the Y-shaped pattern is located relatively near the central well and the other two ends of the Y-shaped pattern are located relatively near the two adjacent corner wells.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 illustrates the modiEied 7 spot pattern contain-ing a vertical central injection well.
Fig. 2 illustrates the well pattern oE Fig. 1 modified by the addition of six horizontal wells between the vertical corner wells.
Fig. 3 illustrates the E'ig. 1 embodiment without a vertical central well. Portions of neighboring patterns are shown in Fig. 3 to demonstrate how the pattern is ~uplicated over additional acreage.
., .
i:~5~56~
Fig. 4 illustrates a 7 spot pattern containing ~ix sets of three horizontal wells each.
-ErrAILE~ UE~SCRIPTION
Although they are more costly and difficult to drill, horizontal wells offer several advantages over vertical wells.
One advantage is the increase in direct contact between the wellhore and the pay zone. The perforated interval per vertical well is li~ited to the pay zone thickness. But for a horizontal well, the perforated interval could be more than ten times that of a vertical wellbore. For example, a 400 foot horizontal well could be run in a 30 foot thick pay zone.
A second advantage of horizontal wells is the ability to complete several hvrizontal wells from a single location and cover a larye drainage area. This is an important advantage when drilling in offshore, Arctic or environmentally sensitive areas where drill site preparation is a major expense. Thirdlyr vertical drilling can be uneconomical in very thin pay zone areas. Properly placed horizontal wells can solve this problem.
For certain thin formations with a bottom w~ater table, horizontal wells could defer and reduce water coning by providiny ~1 low pressure area over a long distance rather -than a single low pressure point as with vertical wells.
6;~
A fourth advantage is the ability to inject or produce fluids orthogonal to those from a vertical well. This provides potential of improving sweep efficiency of a flood and therefore increasing recovery efficiency.
However, horizontal wells are significantly more expensive to drill than vertical wells. In addition, all devel-oped hydrocarbon reservoirs have vertical wells which have already been drilled in the reservoirs. Thus, ways must be found to coordinate the use of horizontal wells with existing vertical well patterns.
The invention method provides a way of achieving horizontal well advantages by using substantially horizontal wells in conjunction with common 7 spot vertical well patterns for improving oil recovery efficiency. The invention requires that six substantially vertical corner wells form a substantially hexagonal well pattern and that a first set of six substantially horizontal wells be drilled within the hexagonal well pattern.
Each of the horizontal wells is drilled so that one end is located relatively near the center of the substantially hexagonal well pattern and the other end of each horizontal well is located relatively near one of the six vertical corner wells.
~ second set of six substantially horizontal wells is added between the corner wells to form a second embodiment. In this modified 7 spot pattern, one end of each well in the second 9~.5~;Z
se~ of horizontal wells is locate~ relatively near a vertical corner well, and the other end of the same horizontal, well is located relatively near an adjacent vertical corner well. It is preferred that a substantially vertical central well be located relatively near the center of the hexagonal well pattern in all of the modified 7 spot embodiments of the invention. In most cases, the vertica] central well will be an injection well. The corner vertical wells may be injectlon or production wells.
Another embodiment entails a different arrangement of horizontal wells within the hexagonal well pattern of a 7 spot.
This embodiment contains six substantially vertical corner wells forming the hexagonal well pattern around a substantially vertical central well located relatively near the center of the hexagonal pattern. Eighteen horizontal wells are drilled in sets of three horizontal wells, each within the confines of the hexagonal pattern. The wells are drilled from six different horizontal well pads located relatively near the center of each of the six triangles formed by the central well and two adjacent corner wells. Each set of three horizontal wells forms a Y-shaped pattern with the common ends of the three horizontal wells terminating at the horizontal welL pad and the opposi-te ends of the three horizontal wells located rela,tively near the central well and the two adjacent corner wells.
~S~S62 Optionally, more than one substantially vertical well may be located at approximately the center of the substantially hexagonal well pattern. Since the vertical central well is most preferably a central injection well, it may be desirable to employ multiple central injection wells. Additional central injection wells may be especially desirable in tight formations where fluid injectivity is a problem.
In the embodiments which do not contain a central injection well, a blind spot of high oil saturation will normally be left in the center of the well pattern. One possible method of recovering the oil from this blind spot is to drill a vertical well and employ a push-pull thermal process.
Formation characteristics and existing vertical wells may require that the pattern be shaped very roughly like a hexagonal figure without 60 angles. Such patterns are intended to be encompassed within the phrase "substantially hexagonal pattern".
The substantially vertical central well and vertical corner wells may be either injection wells or production wells, but are preferably injection wells. The horizontal wells are preferably production wells, but may a:Lso be employed as in-jection welLs under certain operational sequences. In thermal recovery operations, it i5 particularly preferred to inject a thermal fluid into we]ls prior to placing the wells on production :
~5gs62 in order to treat the formation in the immediate vicinity of the future production wells. Various flooding schemes may also be employed in whi~h these wells may be alternately production and injection wells. The vertical and horizontal wells are preferably completed in the bottom third, most preferably, the bottom fifth of the hydrocarbon bearing formation.
The horizontal and vertical wells are all located, or at least perforated, so that a sufficient distance exists between the perforation intervals of each of the horizontal wells and the substantially vertical corner and central wells to prevent direct communication between the different wells. Preferably, the sufficient distance is at least 30 feet of undrilled formation.
Large thief zones or fractures will preferably not run between the perforated intervals of nearby horizontal and vertical wells.
Consequently, care must be taken to avoid locatiny perforations of producing horizontal wells to near the injection well or wells.
A significant advantage of the invention well pattern is that many of the horizontal wells may be drilled and completed from a common horizontal well pad. Thus, drilling C09tS are greatly reduced. For instance, t.he ~ix horizontal wells of the Figs. 1, 2 and 3 embodiments may all be drilled and cornpleted from a single, centrally located horizontal well pad, located near the center of the pattern.
Fiys. 1, 2, 3 and 4 diagram ~he modified 7 spot drill-ing and production patterns. Flgs. 1, 2 and 3 show different but similar modified 7 spot patterns wherein six substantially horiæontal wells 21, 22/ 23, 24, 25 and 26 run betw~en the center of the pattern and the six substantially vertical corner in-jection wells 12, 13, 14, 15, 16 and 17. In Figs. 1 and 2 the central injection well 10 is located at the center of the pat-tern. Fig. 2 also contains a second set of six horizontal wells 34, 35, 36, 37, 38 and 39 all located between the six corner wells 12, 13, 14, 15, 16 and 17.
Fig. 3 illustrates a different embodiment without a central injection well. Horizontal well pads 11 are located at seven different spots in E'ig. 3. The horizontal wells 21~ 22, 23, 24, 25 and 26 were all drilled from horizontal well pad 11 at the center of the pattern. The other horizontal well pads 11 illustrate how the modified 7 spot pattern of Fig. 3 is duplicated over additional acreage. Additional horizontal wells 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 and 52 all radiate from the horizontal well pads 11 of adjacent modified 7 spot patterns.
~ nother embodiment i9 illustrated in Fig. 4 which contains the same si~ corner injection wells 12, 13, 14, 15, 16 and 17 arranged in a hexagonal well pattern around central injection well 10. The Fig~ 4 embodiment also contains i2 18 horizorltal wells grouped into 5iX sets of three horizonkal wells each~ Spots 61, 66, 71, 76, 81 and 86 are the six horizontal well pads for each of the sets of horizontal wells.
From these pads the 18 horizontal wells 62, 63, 64, 67, 68, 69, 72, 73, 74, 7~, 78, 7~, 82, 83, 84, 87, 88 and 89 are all drilled.
Simulation results indicate that the use of horizontal wells in conjunction with vertical wells according to the in-vention are highly effective in recovering oil, particularly oil from blind spot areas in mature steam floods. Horizontal and vertical well comhinations used in the development stage of a reservoir will also minimize b]ind spot formation. The horizontal wells speed oil recovery and thus, shorten project lives. Although the invention method may be practiced in most hydrocarbon reservoirs, production economics will probably limit its use to thermal recovery in heavy oil reservoixs for the next few years.
Horizontal wells must extend from the surface and run a substantially horizontal distance within the hydrocarbon forma-tion. The diameter and length of the horizontal wells in their peroration intervals are not critical, except tllat s~lch factors will affect the well spacing and the economics of the process.
Perforation size and density will be a function of factors such as flow rate, temperatures and pressures employed in a given ~;259S6:2 operation. Such decisions should be determined by conventional drilling criteria, the chara~teristics oE the specific formation, the economics of a given situation, and the well known art of drilling hori~ontal wells.
Many variations of the method of this invention will be apparent to those skilled in the art from the foregoing dis-cussion and examples. Variations can be made without departing from the scope and spirit of the following c]aims.
MODIFIF,~ 7 SPOl' PATTERNS OF HORIZONT~L AND
VERTICAL WELL~ FOR ~MPROVING OIL RECOVERY ~FFICIENCY
(D#78,595-l~F) B~CKG~OUND OF TI~E INVENTION
The inven-tion process is concerned with the enhanced recovery of oil from underground formations. More particularly, the invention relates to a method for recovering hydrocarbons with modified 7 spot well patterns employing horizontal wells placed between vertical wells.
Horizontal wel]s have been investigated and tested for oil recovery for quite some time. Although horizontal wells may in the future be proven economically successful to recover petroleum from many types of formations, at present, the use of horizontal wells is usually limited to formations containing highly viscous crude. It seems likely that horizontal wells will soon become a chief method of producing tar sand formations and other highly viscous oils which cannot be efficiently produced by conventional methods because of their high viscosity.
Various proposals have been set forth for petroleum recovery with horizontal well schemes. Most have involved steam injection or in situ combustion with horizontal wells serving as both injection wells and produci.ng wells~ Steam and combustion processes have been employed to heat viscous formati.ons to lower the viscosity of the petroleum as well as to provide the driving force to push the hydrocarbons toward a well.
~Z5~ Z
U~ S. Patent No. 4,~83,088 illustrates the use of a system of radial horiæontal wells, optionally in conjunction with an inverted 9 spot having an unsually l.arge number of injection wells. U. S. Patent No~ 4,390,0~7 illustrates a scheme of using horizontal and vertical wel.ls together to form a pentagonal shaped pattern which is labeled a ~'5 spot" in the patent, al-though the ar~ recognizes a different pattern as constituting a 5 spot.
S~MMARY OF THE INVENTION
The invention is a method of recovering hydrocarbons from an underground formation by employing modified 7 spot well patterns. The patterns contain six substantially vertical corner wells forming a substantially hexagonal well pattern and six substantially horizontal wells located within the hexagonal well pattern running like the spokes of a wheel between each of the vertical corner wells and the center of the well pattern.
Preferably, the modified 7 spot pattern will also contain a substantially vertical central well located relatively near the center of the substantially hexagonal well pattern.
An alternate elnbodiment conta:ins d second set of six substantially horizon-tal. wells. E.ach of the additional six horizontal wells is located between the corner wells, each horizontal well having one end located re]atively near a vertical ~2~9S62 corner well and the other end located relatively near an adjacent vertical corner well.
A third embodlment contains a distinctly different combination of horizontal wells with the vertical wells of the 7 spot pattern. This pattern contains six substantial]y vertical corner wells forming a substantially hexagonal well pattern, a substantially vertical central well and six sets of three hori zontal wells. Each set of three horizontal wells forms a sub-stantially Y-shaped pattern wherein one of the three ends of the Y-shaped pattern is located relatively near the central well and the other two ends of the Y-shaped pattern are located relatively near the two adjacent corner wells.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 illustrates the modiEied 7 spot pattern contain-ing a vertical central injection well.
Fig. 2 illustrates the well pattern oE Fig. 1 modified by the addition of six horizontal wells between the vertical corner wells.
Fig. 3 illustrates the E'ig. 1 embodiment without a vertical central well. Portions of neighboring patterns are shown in Fig. 3 to demonstrate how the pattern is ~uplicated over additional acreage.
., .
i:~5~56~
Fig. 4 illustrates a 7 spot pattern containing ~ix sets of three horizontal wells each.
-ErrAILE~ UE~SCRIPTION
Although they are more costly and difficult to drill, horizontal wells offer several advantages over vertical wells.
One advantage is the increase in direct contact between the wellhore and the pay zone. The perforated interval per vertical well is li~ited to the pay zone thickness. But for a horizontal well, the perforated interval could be more than ten times that of a vertical wellbore. For example, a 400 foot horizontal well could be run in a 30 foot thick pay zone.
A second advantage of horizontal wells is the ability to complete several hvrizontal wells from a single location and cover a larye drainage area. This is an important advantage when drilling in offshore, Arctic or environmentally sensitive areas where drill site preparation is a major expense. Thirdlyr vertical drilling can be uneconomical in very thin pay zone areas. Properly placed horizontal wells can solve this problem.
For certain thin formations with a bottom w~ater table, horizontal wells could defer and reduce water coning by providiny ~1 low pressure area over a long distance rather -than a single low pressure point as with vertical wells.
6;~
A fourth advantage is the ability to inject or produce fluids orthogonal to those from a vertical well. This provides potential of improving sweep efficiency of a flood and therefore increasing recovery efficiency.
However, horizontal wells are significantly more expensive to drill than vertical wells. In addition, all devel-oped hydrocarbon reservoirs have vertical wells which have already been drilled in the reservoirs. Thus, ways must be found to coordinate the use of horizontal wells with existing vertical well patterns.
The invention method provides a way of achieving horizontal well advantages by using substantially horizontal wells in conjunction with common 7 spot vertical well patterns for improving oil recovery efficiency. The invention requires that six substantially vertical corner wells form a substantially hexagonal well pattern and that a first set of six substantially horizontal wells be drilled within the hexagonal well pattern.
Each of the horizontal wells is drilled so that one end is located relatively near the center of the substantially hexagonal well pattern and the other end of each horizontal well is located relatively near one of the six vertical corner wells.
~ second set of six substantially horizontal wells is added between the corner wells to form a second embodiment. In this modified 7 spot pattern, one end of each well in the second 9~.5~;Z
se~ of horizontal wells is locate~ relatively near a vertical corner well, and the other end of the same horizontal, well is located relatively near an adjacent vertical corner well. It is preferred that a substantially vertical central well be located relatively near the center of the hexagonal well pattern in all of the modified 7 spot embodiments of the invention. In most cases, the vertica] central well will be an injection well. The corner vertical wells may be injectlon or production wells.
Another embodiment entails a different arrangement of horizontal wells within the hexagonal well pattern of a 7 spot.
This embodiment contains six substantially vertical corner wells forming the hexagonal well pattern around a substantially vertical central well located relatively near the center of the hexagonal pattern. Eighteen horizontal wells are drilled in sets of three horizontal wells, each within the confines of the hexagonal pattern. The wells are drilled from six different horizontal well pads located relatively near the center of each of the six triangles formed by the central well and two adjacent corner wells. Each set of three horizontal wells forms a Y-shaped pattern with the common ends of the three horizontal wells terminating at the horizontal welL pad and the opposi-te ends of the three horizontal wells located rela,tively near the central well and the two adjacent corner wells.
~S~S62 Optionally, more than one substantially vertical well may be located at approximately the center of the substantially hexagonal well pattern. Since the vertical central well is most preferably a central injection well, it may be desirable to employ multiple central injection wells. Additional central injection wells may be especially desirable in tight formations where fluid injectivity is a problem.
In the embodiments which do not contain a central injection well, a blind spot of high oil saturation will normally be left in the center of the well pattern. One possible method of recovering the oil from this blind spot is to drill a vertical well and employ a push-pull thermal process.
Formation characteristics and existing vertical wells may require that the pattern be shaped very roughly like a hexagonal figure without 60 angles. Such patterns are intended to be encompassed within the phrase "substantially hexagonal pattern".
The substantially vertical central well and vertical corner wells may be either injection wells or production wells, but are preferably injection wells. The horizontal wells are preferably production wells, but may a:Lso be employed as in-jection welLs under certain operational sequences. In thermal recovery operations, it i5 particularly preferred to inject a thermal fluid into we]ls prior to placing the wells on production :
~5gs62 in order to treat the formation in the immediate vicinity of the future production wells. Various flooding schemes may also be employed in whi~h these wells may be alternately production and injection wells. The vertical and horizontal wells are preferably completed in the bottom third, most preferably, the bottom fifth of the hydrocarbon bearing formation.
The horizontal and vertical wells are all located, or at least perforated, so that a sufficient distance exists between the perforation intervals of each of the horizontal wells and the substantially vertical corner and central wells to prevent direct communication between the different wells. Preferably, the sufficient distance is at least 30 feet of undrilled formation.
Large thief zones or fractures will preferably not run between the perforated intervals of nearby horizontal and vertical wells.
Consequently, care must be taken to avoid locatiny perforations of producing horizontal wells to near the injection well or wells.
A significant advantage of the invention well pattern is that many of the horizontal wells may be drilled and completed from a common horizontal well pad. Thus, drilling C09tS are greatly reduced. For instance, t.he ~ix horizontal wells of the Figs. 1, 2 and 3 embodiments may all be drilled and cornpleted from a single, centrally located horizontal well pad, located near the center of the pattern.
Fiys. 1, 2, 3 and 4 diagram ~he modified 7 spot drill-ing and production patterns. Flgs. 1, 2 and 3 show different but similar modified 7 spot patterns wherein six substantially horiæontal wells 21, 22/ 23, 24, 25 and 26 run betw~en the center of the pattern and the six substantially vertical corner in-jection wells 12, 13, 14, 15, 16 and 17. In Figs. 1 and 2 the central injection well 10 is located at the center of the pat-tern. Fig. 2 also contains a second set of six horizontal wells 34, 35, 36, 37, 38 and 39 all located between the six corner wells 12, 13, 14, 15, 16 and 17.
Fig. 3 illustrates a different embodiment without a central injection well. Horizontal well pads 11 are located at seven different spots in E'ig. 3. The horizontal wells 21~ 22, 23, 24, 25 and 26 were all drilled from horizontal well pad 11 at the center of the pattern. The other horizontal well pads 11 illustrate how the modified 7 spot pattern of Fig. 3 is duplicated over additional acreage. Additional horizontal wells 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 and 52 all radiate from the horizontal well pads 11 of adjacent modified 7 spot patterns.
~ nother embodiment i9 illustrated in Fig. 4 which contains the same si~ corner injection wells 12, 13, 14, 15, 16 and 17 arranged in a hexagonal well pattern around central injection well 10. The Fig~ 4 embodiment also contains i2 18 horizorltal wells grouped into 5iX sets of three horizonkal wells each~ Spots 61, 66, 71, 76, 81 and 86 are the six horizontal well pads for each of the sets of horizontal wells.
From these pads the 18 horizontal wells 62, 63, 64, 67, 68, 69, 72, 73, 74, 7~, 78, 7~, 82, 83, 84, 87, 88 and 89 are all drilled.
Simulation results indicate that the use of horizontal wells in conjunction with vertical wells according to the in-vention are highly effective in recovering oil, particularly oil from blind spot areas in mature steam floods. Horizontal and vertical well comhinations used in the development stage of a reservoir will also minimize b]ind spot formation. The horizontal wells speed oil recovery and thus, shorten project lives. Although the invention method may be practiced in most hydrocarbon reservoirs, production economics will probably limit its use to thermal recovery in heavy oil reservoixs for the next few years.
Horizontal wells must extend from the surface and run a substantially horizontal distance within the hydrocarbon forma-tion. The diameter and length of the horizontal wells in their peroration intervals are not critical, except tllat s~lch factors will affect the well spacing and the economics of the process.
Perforation size and density will be a function of factors such as flow rate, temperatures and pressures employed in a given ~;259S6:2 operation. Such decisions should be determined by conventional drilling criteria, the chara~teristics oE the specific formation, the economics of a given situation, and the well known art of drilling hori~ontal wells.
Many variations of the method of this invention will be apparent to those skilled in the art from the foregoing dis-cussion and examples. Variations can be made without departing from the scope and spirit of the following c]aims.
Claims (23)
1. A modified 7 spot well pattern for recovering hydrocarbons from an underground formation, which comprises:
six substantially vertical corner wells forming a sub-stantially hexagonal well pattern; and a first set of six substantially horizontal wells, each horizontal well having one end located relatively near the center of the substantially hexagonal well pattern and the other end located relatively near one of the six vertical wells.
six substantially vertical corner wells forming a sub-stantially hexagonal well pattern; and a first set of six substantially horizontal wells, each horizontal well having one end located relatively near the center of the substantially hexagonal well pattern and the other end located relatively near one of the six vertical wells.
2. The well pattern of Claim 1, further comprising a second set of six substantially horizontal wells, each horizontal well of the second set having one end located relatively near a vertical corner well and the other end located relatively near an adjacent vertical corner well.
3. The well pattern of Claim 2, further comprising a substantially vertical central well located relatively near the center of the substantially hexagonal well pattern.
4. The well pattern of Claim 3, wherein the central well is an injection well.
5. The well pattern of Claim 2, wherein the first set of horizontal wells are injection wells and the second set of horizontal wells are production wells.
6. The well pattern of Claim 2, wherein the corner wells are injection wells.
7. The well pattern of Claim 2, wherein the corner wells are production wells.
8. The well pattern of Claim 1, further comprising a substantially vertical central well located relatively near the center of the substantially hexagonal well pattern.
9. The well pattern of Claim 8, wherein the central well is an injection well.
10. The well pattern of Claim 8, wherein the central well is a production well.
11. The well pattern of Claim 8, wherein the horizontal wells are production wells.
12. The well pattern of Claim 8, wherein the horizontal wells are injection wells.
13. The well pattern of Claim 8, wherein the corner wells are injection wells.
14. The well pattern of Claim 8, wherein the corner wells are production wells.
15. The well pattern of Claim 8, wherein the horizontal wells are completed in the bottom fifth of the formation.
16. The well pattern of Claim 8, wherein the horizontal wells are drilled form a single well pad located relatively near the center of the substantially hexagonal well pattern.
17. The well pattern of Claim 8, further comprising at least one more substantially vertical well located relatively near the center of the substantially hexagonal well pattern.
18. A modified 7 spot well pattern for recovering hydrocarbons from an underground formation, which comprises:
six substantially vertical corner injection wells form-ing a substantially hexagonal well pat-tern;
a substantially vertical central injection well located relatively near the approximate center of the substantially hexagonal well pattern; and six substantially horizontal production wells, each horizontal well having one end located relatively near the verti-cal central well and the other end located relatively near one of the six vertical corner wells.
six substantially vertical corner injection wells form-ing a substantially hexagonal well pat-tern;
a substantially vertical central injection well located relatively near the approximate center of the substantially hexagonal well pattern; and six substantially horizontal production wells, each horizontal well having one end located relatively near the verti-cal central well and the other end located relatively near one of the six vertical corner wells.
19. A modified 7 spot well pattern for recovering hydrocarbons from an underground formation, which comprises:
six substantially vertical corner wells forming a sub-stantially hexagonal well pattern;
a substantially vertical central well located relative-ly near the center of the substantially hexagonal well patterns;
and six sets of three substantially horizontal wells, each set of three horizontal wells forming a substantially Y-shaped pattern with one of the three ends of each Y-shaped pattern located relatively near the central well and the other two ends of each Y-shaped pattern located relatively near the two adjacent corner wells.
six substantially vertical corner wells forming a sub-stantially hexagonal well pattern;
a substantially vertical central well located relative-ly near the center of the substantially hexagonal well patterns;
and six sets of three substantially horizontal wells, each set of three horizontal wells forming a substantially Y-shaped pattern with one of the three ends of each Y-shaped pattern located relatively near the central well and the other two ends of each Y-shaped pattern located relatively near the two adjacent corner wells.
20. The well pattern of Claim 19, wherein the vertical central well is an injection well.
21. The well pattern of Claim 19, wherein the vertical corner wells are injection wells.
22. The well pattern of Claim 19, wherein the horizontal wells are production wells.
23. A modified 7 spot well pattern for recovering hydrocarbons from an underground formation, which comprises:
six substantially vertical corner injection wells form ing a substantially hexagonal well pattern;
a first set of six substantially horizontal production wells, each horizontal well having one end located relatively near the center of the substantially hexagonal well pattern and the other end located relatively near one of the six vertical corner injection wells;
a substantially vertical central injection well located relatively near the center of the substantially hexagonal well pattern; and a second set of six substantially horizontal production wells, each horizontal well of the second set having one end located relatively near a vertical corner injection well and the other end located relatively near an adjacent vertical corner injection well.
six substantially vertical corner injection wells form ing a substantially hexagonal well pattern;
a first set of six substantially horizontal production wells, each horizontal well having one end located relatively near the center of the substantially hexagonal well pattern and the other end located relatively near one of the six vertical corner injection wells;
a substantially vertical central injection well located relatively near the center of the substantially hexagonal well pattern; and a second set of six substantially horizontal production wells, each horizontal well of the second set having one end located relatively near a vertical corner injection well and the other end located relatively near an adjacent vertical corner injection well.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000533299A CA1259562A (en) | 1987-03-30 | 1987-03-30 | Modified 7 spot patterns of horizontal and vertical wells for improving oil recovery efficiency |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000533299A CA1259562A (en) | 1987-03-30 | 1987-03-30 | Modified 7 spot patterns of horizontal and vertical wells for improving oil recovery efficiency |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1259562A true CA1259562A (en) | 1989-09-19 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000533299A Expired CA1259562A (en) | 1987-03-30 | 1987-03-30 | Modified 7 spot patterns of horizontal and vertical wells for improving oil recovery efficiency |
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| CA (1) | CA1259562A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107091079A (en) * | 2017-06-16 | 2017-08-25 | 新疆国利衡清洁能源科技有限公司 | Coal underground gasification ignition device and method |
| CN110952967A (en) * | 2018-09-27 | 2020-04-03 | 中国石油天然气股份有限公司 | Thickened oil recovery method |
| CN111594132A (en) * | 2020-07-08 | 2020-08-28 | 西南石油大学 | Woven displacement well pattern for fluid injection development of huge thick or multilayer oil and gas reservoir |
-
1987
- 1987-03-30 CA CA000533299A patent/CA1259562A/en not_active Expired
Cited By (4)
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| CN107091079A (en) * | 2017-06-16 | 2017-08-25 | 新疆国利衡清洁能源科技有限公司 | Coal underground gasification ignition device and method |
| CN107091079B (en) * | 2017-06-16 | 2023-09-08 | 新疆国利衡清洁能源科技有限公司 | Underground coal gasification ignition device and method |
| CN110952967A (en) * | 2018-09-27 | 2020-04-03 | 中国石油天然气股份有限公司 | Thickened oil recovery method |
| CN111594132A (en) * | 2020-07-08 | 2020-08-28 | 西南石油大学 | Woven displacement well pattern for fluid injection development of huge thick or multilayer oil and gas reservoir |
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