CA1235652A - Method for obtaining horizontal fractures in an oil reservoir - Google Patents
Method for obtaining horizontal fractures in an oil reservoirInfo
- Publication number
- CA1235652A CA1235652A CA000502573A CA502573A CA1235652A CA 1235652 A CA1235652 A CA 1235652A CA 000502573 A CA000502573 A CA 000502573A CA 502573 A CA502573 A CA 502573A CA 1235652 A CA1235652 A CA 1235652A
- Authority
- CA
- Canada
- Prior art keywords
- wells
- fracturing
- reservoir
- pattern
- horizontal
- 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
Links
- 238000000034 method Methods 0.000 title claims abstract description 12
- 239000012530 fluid Substances 0.000 claims abstract description 19
- 230000000149 penetrating effect Effects 0.000 claims description 2
- 230000002459 sustained effect Effects 0.000 claims 1
- 238000002347 injection Methods 0.000 abstract description 5
- 239000007924 injection Substances 0.000 abstract description 5
- 239000003921 oil Substances 0.000 description 16
- 230000015572 biosynthetic process Effects 0.000 description 12
- 238000005755 formation reaction Methods 0.000 description 12
- 239000011148 porous material Substances 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 5
- 238000010793 Steam injection (oil industry) Methods 0.000 description 4
- 229940090044 injection Drugs 0.000 description 4
- 238000005086 pumping Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 3
- 239000011435 rock Substances 0.000 description 3
- 230000000638 stimulation Effects 0.000 description 3
- 238000004891 communication Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000010795 Steam Flooding Methods 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000000295 fuel oil Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000003027 oil sand Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 230000002277 temperature effect Effects 0.000 description 1
Classifications
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B43/25—Methods for stimulating production
- E21B43/26—Methods for stimulating production by forming crevices or fractures
-
- E—FIXED CONSTRUCTIONS
- E21—EARTH DRILLING; MINING
- E21B—EARTH DRILLING, e.g. DEEP 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
- E21B43/17—Interconnecting two or more wells by fracturing or otherwise attacking the formation
Abstract
"METHOD FOR OBTAINING HORIZONTAL FRACTURES
IN AN OIL RESERVOIR"
ABSTRACT OF THE DISCLOSURE
A closed pattern of wells is completed in an oil reservoir which is characterized by a tectonic stress regime conducive to vertical fracturing. Fluid is injected into the outlying wells of the pattern at sufficiently high pressures to create vertical hydraulic fractures at these wells. Thus pressure is applied to the reservoir from the corners of the pattern inwardly, to alter the stress regime to one conducive to horizontal fracturing. The central well is then subjected to fluid injection while pressure is maintained on the outlying wells,to generate a horizontal fracture system emanating from the central well.
IN AN OIL RESERVOIR"
ABSTRACT OF THE DISCLOSURE
A closed pattern of wells is completed in an oil reservoir which is characterized by a tectonic stress regime conducive to vertical fracturing. Fluid is injected into the outlying wells of the pattern at sufficiently high pressures to create vertical hydraulic fractures at these wells. Thus pressure is applied to the reservoir from the corners of the pattern inwardly, to alter the stress regime to one conducive to horizontal fracturing. The central well is then subjected to fluid injection while pressure is maintained on the outlying wells,to generate a horizontal fracture system emanating from the central well.
Description
`` 1~3~ii65~
l FIELD OF THE INVENTION
l FIELD OF THE INVENTION
2 This invention relates to a method for completing and operating
3 a pattern of wells penetrating an oil zone, so as to change the stress
4 regime within the oil zone in the area bounded by the outlying wells of the pattern, with the result that the oil zone adjacent an injec-tion well 6 within the pattern may be fractured in a generally horizontal plane.
8 The present invention has been developed in conjunction with 9 pilot field tests in the Clearwater and Grand Rapids oil sand formations in the Cold Lake region of Alberta. While the invention is not limited 11 to these reservoirs, it will be discussed below in connection with their 12 specific characteristics.
13 It is now well accepted that many oil reservoirs tend to 14 fracture vertically when fluid is injected into the virgin formation at fracturing pressure. In the case of Cold Lake, the evidence indicates that 16 horizontal fracturing will tend to occur down to a depth of about 250 17 metres. From about 250 to 350 metres, the fracturing may be either verti-18 cal or horizontal. And below 350 metres the fracturing tends to occur 19 in a vertical plane. As the oil production zones are below 350 metres, vertical fracturing is the norm in the Cold Lake area.
3~i~5~
1 To produce the heavy oil at Cold Lake it is necessary to heat 2 the formation to reduce the viscosity of the oil. This is normally done 3 using high quality steam injection. The native state reservoir fluid 4 transmissibilities are low, requiring that steam be injected at formation fracturing pressure in order to achieve sufficient injectivity to accomplish 6 the desired heating. Wells are normally steam stimulated for 5 to 10 7 cycles after which steam flooding between wells may be implemented.
The creation of vertical fractures generally results in low recovery and 9 process efficiency. Inter-well communication developed by means of ~ vertical fractures is not conducive to high sweep efficiency in the 11 flooding mode. In addition, heating a reservoir through vertical 12 fractures is not efficient. The steam has a tendency to ride upwardly 13 and it concentrates in the upper reaches of the fracture losing heat 4 to the non-oil-bearing overlying rock. Thus the steam volume required to heat the full oil reservoir tends to be very high when one is working 16 with a vertically fractured formation.
17 Ideally, one would like to create a horizontal, pancake-like 1~ fracture system extending from the central injection well to the outlying19 production wells, preferably at an elevation near the bottom/middle of ~ the vertical extent of the oil reservoir. Such a fracture system would 21 ensure inter-well communication and efficient steam utilization. This 22 would result in overall improvement in process efficiency.
23 The formation of horizontal fractures during steam stimulation 24 would result in higher areal heat coverage and associated oil production in comparison with that obtained from vertical fractures.
~Z35~i5;~
1 It is commonly accepted that the plane in which -fracturing 2 occurs is dictated by the tectonic stress regime present in the formation.
3 The fracture propagates in a plane perpendicular to the plane of least 4 principal stress in the formation.
It has been suggested in the patent literature that the 6 tectonic stress regime in the reservoir can be altered to chanye fracture 7 orientation. Patents of interest in this regard are those issued to C. S. Matthews et al (U.S. 3,455,391), P. J. Closmann et al (U.S.
9 3,613,785) , and L. Z. Shuck (U.S. 4,005,750).
More specifically, Matthews teaches fracturing the formation 11 around a well vertically and then injecting fluid at increasing tempera-12 ture and under increasing pressure to cause thermal stressing of the rock 13 in a horizontal direction, until a horizontal fracture is induced.
14 It is to be noted that Matthews works with a single well.
Also he relies on injecting a hot fluid to induce thermal changes in the 16 rock, to change the stress regime.
17 Closmann does basically the same as Matthews, in that he 1~ utilizes thermal change to alter the stress regime to one conducive to 19 horizontal fracturing. By way of difference, Olosmann injects the heating medium at one well to induce a change in stress regime at a neighbouring 21 second well. He then teaches fracturing through the second well.
22 Shuck seeks to obtain fracturing in a plane at 90 to the 23 natural fracture plane (i.e. the plane of maximum horizontal tectonic 24 stress). So he teaches first of all creating a vertical fracture from a well, using hydraulic pressure. He then teaches pumping fluid under 26 pressure into this vertical fracture, to incréase the stress in a hori-27 zontal plane. He then requires that an adjacent well be fractured, while 23 pumping is maintained at the first well. He states that the fracture 29 from the second well will be vertical but orthogonal (perpendicular) to the first fracture. In this manner, a network of intersecting fractures 31 can be produced.
~Z3S~5;~
1 It is also the objective of the present invention to achieve 2 horizontal fracturing by altering the stress regime in an oil reservoir, 3 which normally would fracture vertically. But in the present case the 4 means by which this is attained is different from the methods taught in the prior art.
6 With this background in mind, it is now appropriate to turn to 7 the present invention.
SUMMARY OF THE INVENTION
The invention is based on results obtained at field pilot projects conducted at Cold Lake. These projects involved fracturing the 11 virgin reservoir adjacent each well by means of steam injection.
12 As previously mentioned, the wells at Cold Lake normally 13 fracture vertically. This was confirmed by fracturing with steam a well 14 surrounded by closely spaced observation wells. The temperature observations at the surrounding wells, coupled with the level of the 16 pumping pressure required to inject the steam, pointed toward the nature 17 of the fracture system being vertical. The temperature profiles indicated 1~ a narrow hot zone was emanating generally linearly from the well along 19 the regional plane orthogonal to the least compressive stress.
~ A multi-well pilot was conducted in which cyclic steam ~1 stimulation at fracturing pressure was practised. After several cycles 22 of steam stimulation, there was evidence from temperature observations 23 that horizontal fractures occurred in isolated cases due to an altering 24 stress regime.
It was more desirable, however~ to obtain consistent and 26 controlled hori~ontal fractures from the outset. At this point, the 27 strategy was evolved to change the stress regime within the bounds of a 28 pattern to one generally uniformly conducive to horizontal fracturing.
~Z~ 652 1 The method which was developed comprised the following combination 2 of steps and conditions:
3 (a) vertically fracture the oil reservoir through each of the 4 outlying wells of a pattern and inject sufficient fluid in a generally un;form manner into the oil reservoir through 6 the outlying wells so as to alter the stress regime, 7 throughout the horizontal extent of that portion of the 8 oil reservoir bounded by the pattern, to one conducive 9 to horizontal fracturing; and (b) whilst preferably maintaining pressure on the outlying 11 wells, then fracture the oil reservoir through the central 12 well of the pattern to create and extend a horizontal 13 fracture system within the pattern.
14 It will be noted that the invention is practised within a "closed" pattern, such as a convcntional 5-spot, and that the change in 16 stress regime is accomplished in the main by pumping fluid under pressure 17 into the boundary wells of the pattern.
18 Our analysis has indicated that it is the pressure actjng on the lg fracture surface.that.most.significantly alters the stress-regime~ This observation arises from analysis of stress changes induced by pressure 21 on fracture surface, pore fluid pressure changes and temperature changes.
22 Assuming the reservoir material to be homogeneous, isotropic and linear, 23 the relation among stresses, strains, pore fluid pressure and temperature24 may be written as:
25 ~jj = 2G[F jj + ~ ~kk ~jj] (P-Pr)~jj - ~ (T-Tr)~ j j~ i, j=1~2~3~
~ 3S~
1 where~ = stress components, 2 jj = strain components, 3 P = pore fluid pressure, 4 Pr = initial formation pore fluid pressure, T = temperature, 6 Tr = initial formation temperature, 7 E = Young's modulus 9 8 G = shear modulus 9 v = Poisson's ratio ~ = coefficient of thermal expansion, = Kronecker delta; = 1 when i=j, = 0 otherwise.
12 Note that equation (1) employs the index notation and the 13 summation convention, where variables with repeated indices are summed 14 over 1, 2 and 3.
The equations of equilibrium for the system in question are:
1~ a~jj + fj = 0 ~ 1,2,3, (2) axj 17 where: Xj = co-ordinate in the j-direction, 18 fj = body force distribution in the i-direction.
19 Using the definition of strains as:
~jj = 1 (auj + ~uj ) , i,j=1,2,3, (3) 21 where: u; = displacement in the i-direction, ~35~i52 1 and substituting equation (1) into equation (2), the following partial 2 differential equations may be obtained:
3 G a2uj -~ G a uk axkaxk l-2v axkaxj 4 = -f ~ a(P~Pr) + E~ ~(T Tr) , j, j=1,2,3. (4) ~Xj ~ axj Equation (4) may be solved using a numerical technique known in the art 6 as the finite element method.
7 This analysis indicated that it is the pressure acting on the 8 fracture surface that most significantly alters the stress regime - as 9 compared to the changes arising from pore Fluid pressure and thermal effects.
11 By injecting into the boundary wells of a closed pattern, 12 the stress changes are induced throughout the horizontal extent 13 of the pattern. Since the pressure applied to the fracture face, and 14 not the pore fluid pressure nor the temperature effects, is the dominant factor in achieving the stress changes, the present process may lG be used by injecting fluids at reservoir temperature.
35i65'~
1 DESCRIPTION OF THE PREFERRED EM~ODIMENT
2 The method is exemplified by the following example:
3 A 5-spot pattern of wells is completed in conventional fashion 4 in the Clearwater sand at Cold Lake. A11 wells are equipped and completed for thermal injection and production. T'ne central well however is completed 6 over a narrow interval for limited fluid entry into the lower part of the 7 oil producing formation.
A pre-determined volume of fluid is then injected at fracturing ~ pressure through each of the outlying wells to increase the tectonic stresses within the pattern. More particularly a steam volume of 5,000 11 to 15,000 m3 cold water equivalent at rates ranging from 100 to 300 m3/d 12 are used.
13 Then steam or hot water is injected into the reservoir through 14 the central well while pressure is maintained on the outlying wells.
The steam slug size used in the central well is from 5,000 to 20,000 m3 16 initially, injected at 100 to 300 m3/d.
17 The injection at the central well begins near the end of the 1~ steam injection at the outlying wells. The outlying wells are shut-in 19 and/or pressure malntained until the end of steam injection at the central well, at which time all wells, including the central well, are placed 21 on production.
22 Temperature observations in the wells indicate that the 23 fracture system emanating from the central well is generally horizontal 24 in nature.
_ g
8 The present invention has been developed in conjunction with 9 pilot field tests in the Clearwater and Grand Rapids oil sand formations in the Cold Lake region of Alberta. While the invention is not limited 11 to these reservoirs, it will be discussed below in connection with their 12 specific characteristics.
13 It is now well accepted that many oil reservoirs tend to 14 fracture vertically when fluid is injected into the virgin formation at fracturing pressure. In the case of Cold Lake, the evidence indicates that 16 horizontal fracturing will tend to occur down to a depth of about 250 17 metres. From about 250 to 350 metres, the fracturing may be either verti-18 cal or horizontal. And below 350 metres the fracturing tends to occur 19 in a vertical plane. As the oil production zones are below 350 metres, vertical fracturing is the norm in the Cold Lake area.
3~i~5~
1 To produce the heavy oil at Cold Lake it is necessary to heat 2 the formation to reduce the viscosity of the oil. This is normally done 3 using high quality steam injection. The native state reservoir fluid 4 transmissibilities are low, requiring that steam be injected at formation fracturing pressure in order to achieve sufficient injectivity to accomplish 6 the desired heating. Wells are normally steam stimulated for 5 to 10 7 cycles after which steam flooding between wells may be implemented.
The creation of vertical fractures generally results in low recovery and 9 process efficiency. Inter-well communication developed by means of ~ vertical fractures is not conducive to high sweep efficiency in the 11 flooding mode. In addition, heating a reservoir through vertical 12 fractures is not efficient. The steam has a tendency to ride upwardly 13 and it concentrates in the upper reaches of the fracture losing heat 4 to the non-oil-bearing overlying rock. Thus the steam volume required to heat the full oil reservoir tends to be very high when one is working 16 with a vertically fractured formation.
17 Ideally, one would like to create a horizontal, pancake-like 1~ fracture system extending from the central injection well to the outlying19 production wells, preferably at an elevation near the bottom/middle of ~ the vertical extent of the oil reservoir. Such a fracture system would 21 ensure inter-well communication and efficient steam utilization. This 22 would result in overall improvement in process efficiency.
23 The formation of horizontal fractures during steam stimulation 24 would result in higher areal heat coverage and associated oil production in comparison with that obtained from vertical fractures.
~Z35~i5;~
1 It is commonly accepted that the plane in which -fracturing 2 occurs is dictated by the tectonic stress regime present in the formation.
3 The fracture propagates in a plane perpendicular to the plane of least 4 principal stress in the formation.
It has been suggested in the patent literature that the 6 tectonic stress regime in the reservoir can be altered to chanye fracture 7 orientation. Patents of interest in this regard are those issued to C. S. Matthews et al (U.S. 3,455,391), P. J. Closmann et al (U.S.
9 3,613,785) , and L. Z. Shuck (U.S. 4,005,750).
More specifically, Matthews teaches fracturing the formation 11 around a well vertically and then injecting fluid at increasing tempera-12 ture and under increasing pressure to cause thermal stressing of the rock 13 in a horizontal direction, until a horizontal fracture is induced.
14 It is to be noted that Matthews works with a single well.
Also he relies on injecting a hot fluid to induce thermal changes in the 16 rock, to change the stress regime.
17 Closmann does basically the same as Matthews, in that he 1~ utilizes thermal change to alter the stress regime to one conducive to 19 horizontal fracturing. By way of difference, Olosmann injects the heating medium at one well to induce a change in stress regime at a neighbouring 21 second well. He then teaches fracturing through the second well.
22 Shuck seeks to obtain fracturing in a plane at 90 to the 23 natural fracture plane (i.e. the plane of maximum horizontal tectonic 24 stress). So he teaches first of all creating a vertical fracture from a well, using hydraulic pressure. He then teaches pumping fluid under 26 pressure into this vertical fracture, to incréase the stress in a hori-27 zontal plane. He then requires that an adjacent well be fractured, while 23 pumping is maintained at the first well. He states that the fracture 29 from the second well will be vertical but orthogonal (perpendicular) to the first fracture. In this manner, a network of intersecting fractures 31 can be produced.
~Z3S~5;~
1 It is also the objective of the present invention to achieve 2 horizontal fracturing by altering the stress regime in an oil reservoir, 3 which normally would fracture vertically. But in the present case the 4 means by which this is attained is different from the methods taught in the prior art.
6 With this background in mind, it is now appropriate to turn to 7 the present invention.
SUMMARY OF THE INVENTION
The invention is based on results obtained at field pilot projects conducted at Cold Lake. These projects involved fracturing the 11 virgin reservoir adjacent each well by means of steam injection.
12 As previously mentioned, the wells at Cold Lake normally 13 fracture vertically. This was confirmed by fracturing with steam a well 14 surrounded by closely spaced observation wells. The temperature observations at the surrounding wells, coupled with the level of the 16 pumping pressure required to inject the steam, pointed toward the nature 17 of the fracture system being vertical. The temperature profiles indicated 1~ a narrow hot zone was emanating generally linearly from the well along 19 the regional plane orthogonal to the least compressive stress.
~ A multi-well pilot was conducted in which cyclic steam ~1 stimulation at fracturing pressure was practised. After several cycles 22 of steam stimulation, there was evidence from temperature observations 23 that horizontal fractures occurred in isolated cases due to an altering 24 stress regime.
It was more desirable, however~ to obtain consistent and 26 controlled hori~ontal fractures from the outset. At this point, the 27 strategy was evolved to change the stress regime within the bounds of a 28 pattern to one generally uniformly conducive to horizontal fracturing.
~Z~ 652 1 The method which was developed comprised the following combination 2 of steps and conditions:
3 (a) vertically fracture the oil reservoir through each of the 4 outlying wells of a pattern and inject sufficient fluid in a generally un;form manner into the oil reservoir through 6 the outlying wells so as to alter the stress regime, 7 throughout the horizontal extent of that portion of the 8 oil reservoir bounded by the pattern, to one conducive 9 to horizontal fracturing; and (b) whilst preferably maintaining pressure on the outlying 11 wells, then fracture the oil reservoir through the central 12 well of the pattern to create and extend a horizontal 13 fracture system within the pattern.
14 It will be noted that the invention is practised within a "closed" pattern, such as a convcntional 5-spot, and that the change in 16 stress regime is accomplished in the main by pumping fluid under pressure 17 into the boundary wells of the pattern.
18 Our analysis has indicated that it is the pressure actjng on the lg fracture surface.that.most.significantly alters the stress-regime~ This observation arises from analysis of stress changes induced by pressure 21 on fracture surface, pore fluid pressure changes and temperature changes.
22 Assuming the reservoir material to be homogeneous, isotropic and linear, 23 the relation among stresses, strains, pore fluid pressure and temperature24 may be written as:
25 ~jj = 2G[F jj + ~ ~kk ~jj] (P-Pr)~jj - ~ (T-Tr)~ j j~ i, j=1~2~3~
~ 3S~
1 where~ = stress components, 2 jj = strain components, 3 P = pore fluid pressure, 4 Pr = initial formation pore fluid pressure, T = temperature, 6 Tr = initial formation temperature, 7 E = Young's modulus 9 8 G = shear modulus 9 v = Poisson's ratio ~ = coefficient of thermal expansion, = Kronecker delta; = 1 when i=j, = 0 otherwise.
12 Note that equation (1) employs the index notation and the 13 summation convention, where variables with repeated indices are summed 14 over 1, 2 and 3.
The equations of equilibrium for the system in question are:
1~ a~jj + fj = 0 ~ 1,2,3, (2) axj 17 where: Xj = co-ordinate in the j-direction, 18 fj = body force distribution in the i-direction.
19 Using the definition of strains as:
~jj = 1 (auj + ~uj ) , i,j=1,2,3, (3) 21 where: u; = displacement in the i-direction, ~35~i52 1 and substituting equation (1) into equation (2), the following partial 2 differential equations may be obtained:
3 G a2uj -~ G a uk axkaxk l-2v axkaxj 4 = -f ~ a(P~Pr) + E~ ~(T Tr) , j, j=1,2,3. (4) ~Xj ~ axj Equation (4) may be solved using a numerical technique known in the art 6 as the finite element method.
7 This analysis indicated that it is the pressure acting on the 8 fracture surface that most significantly alters the stress regime - as 9 compared to the changes arising from pore Fluid pressure and thermal effects.
11 By injecting into the boundary wells of a closed pattern, 12 the stress changes are induced throughout the horizontal extent 13 of the pattern. Since the pressure applied to the fracture face, and 14 not the pore fluid pressure nor the temperature effects, is the dominant factor in achieving the stress changes, the present process may lG be used by injecting fluids at reservoir temperature.
35i65'~
1 DESCRIPTION OF THE PREFERRED EM~ODIMENT
2 The method is exemplified by the following example:
3 A 5-spot pattern of wells is completed in conventional fashion 4 in the Clearwater sand at Cold Lake. A11 wells are equipped and completed for thermal injection and production. T'ne central well however is completed 6 over a narrow interval for limited fluid entry into the lower part of the 7 oil producing formation.
A pre-determined volume of fluid is then injected at fracturing ~ pressure through each of the outlying wells to increase the tectonic stresses within the pattern. More particularly a steam volume of 5,000 11 to 15,000 m3 cold water equivalent at rates ranging from 100 to 300 m3/d 12 are used.
13 Then steam or hot water is injected into the reservoir through 14 the central well while pressure is maintained on the outlying wells.
The steam slug size used in the central well is from 5,000 to 20,000 m3 16 initially, injected at 100 to 300 m3/d.
17 The injection at the central well begins near the end of the 1~ steam injection at the outlying wells. The outlying wells are shut-in 19 and/or pressure malntained until the end of steam injection at the central well, at which time all wells, including the central well, are placed 21 on production.
22 Temperature observations in the wells indicate that the 23 fracture system emanating from the central well is generally horizontal 24 in nature.
_ g
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of completing and operating a closed pattern of wells penetrating an oil reservoir having a stress regime normally conducive to vertical fracturing, said pattern comprising a central well and a plurality of surrounding outlying wells, comprising:
fracturing the reservoir through the outlying wells to create substantially vertical fractures extending from said wells;
injecting sufficient fluid at fracturing pressure through the outlying wells to alter the stress regime, in that portion of the reservoir bounded by said outlying wells, to one conducive to horizontal fracturing;
and then fracturing the reservoir through the central well while the altered stress regime is sustained in said reservoir portion, to create a substantially horizontal fracture within said reservoir portion.
fracturing the reservoir through the outlying wells to create substantially vertical fractures extending from said wells;
injecting sufficient fluid at fracturing pressure through the outlying wells to alter the stress regime, in that portion of the reservoir bounded by said outlying wells, to one conducive to horizontal fracturing;
and then fracturing the reservoir through the central well while the altered stress regime is sustained in said reservoir portion, to create a substantially horizontal fracture within said reservoir portion.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000502573A CA1235652A (en) | 1986-02-24 | 1986-02-24 | Method for obtaining horizontal fractures in an oil reservoir |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000502573A CA1235652A (en) | 1986-02-24 | 1986-02-24 | Method for obtaining horizontal fractures in an oil reservoir |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1235652A true CA1235652A (en) | 1988-04-26 |
Family
ID=4132541
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000502573A Expired CA1235652A (en) | 1986-02-24 | 1986-02-24 | Method for obtaining horizontal fractures in an oil reservoir |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1235652A (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6070663A (en) * | 1997-06-16 | 2000-06-06 | Shell Oil Company | Multi-zone profile control |
| US9410406B2 (en) | 2013-08-14 | 2016-08-09 | BitCan Geosciences & Engineering Inc. | Targeted oriented fracture placement using two adjacent wells in subterranean porous formations |
| US9624760B2 (en) | 2013-05-31 | 2017-04-18 | Bitcan Geosciences + Engineering | Method for fast and uniform SAGD start-up enhancement |
| US10012064B2 (en) | 2015-04-09 | 2018-07-03 | Highlands Natural Resources, Plc | Gas diverter for well and reservoir stimulation |
| US10344204B2 (en) | 2015-04-09 | 2019-07-09 | Diversion Technologies, LLC | Gas diverter for well and reservoir stimulation |
| US10982520B2 (en) | 2016-04-27 | 2021-04-20 | Highland Natural Resources, PLC | Gas diverter for well and reservoir stimulation |
-
1986
- 1986-02-24 CA CA000502573A patent/CA1235652A/en not_active Expired
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6070663A (en) * | 1997-06-16 | 2000-06-06 | Shell Oil Company | Multi-zone profile control |
| US9624760B2 (en) | 2013-05-31 | 2017-04-18 | Bitcan Geosciences + Engineering | Method for fast and uniform SAGD start-up enhancement |
| US9410406B2 (en) | 2013-08-14 | 2016-08-09 | BitCan Geosciences & Engineering Inc. | Targeted oriented fracture placement using two adjacent wells in subterranean porous formations |
| US10012064B2 (en) | 2015-04-09 | 2018-07-03 | Highlands Natural Resources, Plc | Gas diverter for well and reservoir stimulation |
| US10344204B2 (en) | 2015-04-09 | 2019-07-09 | Diversion Technologies, LLC | Gas diverter for well and reservoir stimulation |
| US10385258B2 (en) | 2015-04-09 | 2019-08-20 | Highlands Natural Resources, Plc | Gas diverter for well and reservoir stimulation |
| US10385257B2 (en) | 2015-04-09 | 2019-08-20 | Highands Natural Resources, PLC | Gas diverter for well and reservoir stimulation |
| US10982520B2 (en) | 2016-04-27 | 2021-04-20 | Highland Natural Resources, PLC | Gas diverter for well and reservoir stimulation |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5273111A (en) | Laterally and vertically staggered horizontal well hydrocarbon recovery method | |
| US4635720A (en) | Heavy oil recovery process using intermittent steamflooding | |
| US5005645A (en) | Method for enhancing heavy oil production using hydraulic fracturing | |
| US4633948A (en) | Steam drive from fractured horizontal wells | |
| US5860475A (en) | Mixed well steam drive drainage process | |
| US5417283A (en) | Mixed well steam drive drainage process | |
| US4982786A (en) | Use of CO2 /steam to enhance floods in horizontal wellbores | |
| US4476932A (en) | Method of cold water fracturing in drainholes | |
| US3501201A (en) | Method of producing shale oil from a subterranean oil shale formation | |
| US5085276A (en) | Production of oil from low permeability formations by sequential steam fracturing | |
| US3410344A (en) | Fluid injection method | |
| US2915122A (en) | Fracturing process with superimposed cyclic pressure | |
| US4612989A (en) | Combined replacement drive process for oil recovery | |
| US4130163A (en) | Method for recovering viscous hydrocarbons utilizing heated fluids | |
| US3810510A (en) | Method of viscous oil recovery through hydraulically fractured wells | |
| US2876838A (en) | Secondary recovery process | |
| CA2251157C (en) | Process for sequentially applying sagd to adjacent sections of a petroleum reservoir | |
| CA1235652A (en) | Method for obtaining horizontal fractures in an oil reservoir | |
| CA1088416A (en) | Thermal oil recovery method | |
| US3330353A (en) | Thermal soak zones by fluidized fractures in unconsolidated, petroleum producing reservoirs | |
| CA1303974C (en) | Method of producing viscous oil from subterranean formations | |
| US4733726A (en) | Method of improving the areal sweep efficiency of a steam flood oil recovery process | |
| CA1264657A (en) | Enhanced hydrocarbon recovery process utilizing thermoelastic fracturing | |
| US4109723A (en) | Thermal oil recovery method | |
| Kry | Field observations of steam distribution during injection to the Cold Lake reservoir |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |