CA1166151A - Combination solvent injection-electric current application method for establishing fluid communication through heavy oil formation - Google Patents
Combination solvent injection-electric current application method for establishing fluid communication through heavy oil formationInfo
- Publication number
- CA1166151A CA1166151A CA000388179A CA388179A CA1166151A CA 1166151 A CA1166151 A CA 1166151A CA 000388179 A CA000388179 A CA 000388179A CA 388179 A CA388179 A CA 388179A CA 1166151 A CA1166151 A CA 1166151A
- Authority
- CA
- Canada
- Prior art keywords
- injection
- solvent
- heavy oil
- electric current
- fluid communication
- 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
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
- E21B43/16—Enhanced recovery methods for obtaining hydrocarbons
- E21B43/24—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection
- E21B43/2401—Enhanced recovery methods for obtaining hydrocarbons using heat, e.g. steam injection by means of electricity
-
- 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
-
- 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
"COMBINATION SOLVENT INJECTION-ELECTRIC CURRENT
APPLICATION METHOD FOR ESTABLISHING FLUID
COMMUNICATION THROUGH HEAVY OIL FORMATION"
ABSTRACT OF THE DISCLOSURE
A fluid communication channel is developed between injection and product wells in a heavy oil formation by simul-taneously injecting a solvent for the oil and passing electric current through the formation.
APPLICATION METHOD FOR ESTABLISHING FLUID
COMMUNICATION THROUGH HEAVY OIL FORMATION"
ABSTRACT OF THE DISCLOSURE
A fluid communication channel is developed between injection and product wells in a heavy oil formation by simul-taneously injecting a solvent for the oil and passing electric current through the formation.
Description
ll~ S~
2 Field of the Invention
3 This invention relates to a method for establishing a fluid
4 communication channel between ;njection and production wells in a heavy oil reservoir. More particularly, the invention is concerned with 6 injecting a solvent into the formation while simultaneously passing 7 electric current between electrodes positioned in the wells.
8 Description of the Prior Art 9 The invention has been developed in connect;on with the tar sand of the Athabasca reservoir in Alberta, Canada. It has application 11 to other heavy oil reservoirs. However, it will be described below in 12 connection with such tar sand and the problems which characterize it.
13 Athabasca tar sand comprises unconsolidated or discrete 14 sand particles encapsulated in thin envelopes of water. The void spaces between the water-sheathed sand grains are filled with the 16 bitumen which is to be recovered. As a formation, the unheated tar 17 sand is relatively impermeable. Fluids, such as steam or flood solution, 18 cannot easily be injected into the formation. This difficulty is further 19 compounded by the relatively thin overburden (600' to 1200') overlying the formation. There is a likelihood that formation fracturing with the 21 use of high injection pressures will result.
22 One approach which has been investigated to get around these 23 problems has involved trying to first develop a narrow, permeable 24 interwell channel or path extending through the formation between the injection and production wells, using special techniques. Once this 26 channel is open and fluid communication between the wells exists, it 27 is then possible to inject steam into the channel. The injected steam 28 heats the bitumen around the channel. This now-mobile bitumen flows 29 into the channel and is driven to the production well. In this manner, 1 the channel is gradually widened and the formation bitumen may be 2 recovered.
3 One specific method previ.ously sugges.ted for developing 4 such a channel involves inject;ng a bitumen solvent, such as naphtha or kerosene, directly into the untreated reservoir. It would be antici-6 pated that the solvent would move through the formation through the 7 latter's water and gas phases and would reduce the viscosity of bitumen8 which it contacted, thereby mobilizing the bitumen. However, when this g method is practised, particularly wi.th formations having a relatively low water and gas saturation, it is frequently found that the injection 11 pressure gradually increases and eventually reaches an unacceptable 12 level, before breakthrough to the production well is achieved.
13 SUMMARY OF THE IN~ENTION
14 In accordance with the invention, it has been found that simultaneously applying electric current to the formation while injecting 16 a solvent for heavy oil provides an improved process for opening up a 17 fluid communication channel between injection and production points in a 18 previously unheated heavy oil reservoir. Solvent injection may be 19 continued until there is a breakthrough at the production well, or a smaller solvent slug may be followed with a drive fluid to force the 21 solvent as far as the production well.
22 Broadly stated, the invention is a method for opening a 23 fluid communication channel between injection and production wells in a24 previously unheated heavy oil reservoir, which comprises: injecting a solvent for the heavy oil into the reservoir; and, while solvent is 26 moving through the reservoir, passing electric current through the 27 reservoir between electrodes positioned in the injection and production28 wells.
1 DESCRIPTION OF THE DRAWI~G
2 Figure 1 is a schematic showing the laboratory apparatus 3 used to carry out the experiments reported hereinbelow.
4 Figure 2 is a plot showing the variation in injection pressure and oil sand temperature which occurs during solvent injection 6 without and with the application of electrical potential.
8 The solvent used is a low viscos;ty hydrocarbon which will g reduce the viscosity of the heavy oil or bitumen through solubili~ation and dilution when it contacts it. Suitable examples are naphtha, 11 kerosene,diesel and fuel oil, gas condensate and light crude.
12 The electrical current applied may be D.C. or A.C. In the case of D.C., it is preferred that the polarity of the electrode at the injection point be positive, with that at the production point being negative. An electroosmotic effect which assists in the penetration 16 of the solvent is obtained by this preferred D.C. arrangement.
17 The electrical current is applied concurrently with injection 18 of the solvent. This may be done throughout the solvent injection period19 or alternatively only during part of the period, when the injection pressure becomes high; the former is preferred, as it provides a con-21 tinuing directional influence on the advancing solvent.
22 Following breakthrough of the solvent at the production 23 point, one of a number of water based fluid drives may be used to cause 24 the solvent and bitumen to move to the production well. This provides for an early solvent-bitumen recovery and produces a more dependable 26 communication path for subsequent thermal methods.
27 The invention is exemplified by the following examples.
1 Experimental Apparatus 2 The experiments associated with this invention were carried 3 out in apparatus schematically shown ;n Figure 1. More particularly, 4 there was provided a fibrecast tube 1 having a length of 3 feet and inside d;ameter of 3 inches. This tube was packed with approximately 15 6 pounds of tar sand. Electrodes 2, 3 were provided in the form of floating 7 pistons, one being positioned in the tube at each end of the charge 8 Of tar sand. Each electrode was a cylindrical steel body having 0-ring g seals mounted in its outer surface~ The electrodes were adapted to slide within the tube when pressurized at their outer ends, while maintaining 11 the tube contents sealed.
12 The tube 1 was mounted in a cylindrical vessel 4. Pres-13 surized nitrogen could be supplied from a bottle 5 through line 6 to 14 the interior of the vessel 4. This nitrogen pressure would act to force the piston electrodes 2,3 inwardly, thereby compressing the tar 16 sand charge and simulating the application of overburden pressure.
17 Cold water and steam sources 7, 8 were connected by a 18 suitable valve and line system 9 to a jacket 10 surrounding the vessel 19 4. Thus the temperature of the vessel contents could be controlled.
A cylinder 11 containing a floating piston 12 was provided 21 to supply solvent or drive fluid through the line 13, extending 22 through the lower piston electrode 2, to the core. A water reservoir 2~ 14 was connected through the line 15 and metering pump 16 with the 24 lower end of the cylinder 11. Thus water could be pumped into the cylinder 11 to displace the floating p;ston 12 and force the charge of 26 solvent or drive fluid into the lower end of the tar sand column 17.
27 Electric power was supplied into vessel 4 by means of 28 ceramic feed-through devices 18 and the electrodes 2, 3, from an AC/DC
29 power source 19. The source 19 was capable of generating a variable voltage differential across the electrodes 2,3, of from 0 to 750 volts.
i51 1 A product line 20 connected with an outlet bore ~not shown) 2 extending through the upper electrode 3, delivered production to a glass 3 receiver 21.
This example demonstrated that cold solvent injection would 6 enter tar sand and initiate a communications path. However pressure 7 differential build-up did occur; th;s differential was reduced when 8 electrical assist was employed and communication between injection and 9 production points was successfully re-established and maintained.
The 3" diameter fibrecast tube 1 was first equipped at 11 its lower end with the electrode 2. This electrode was one faced with a 12 1/8" thickness of porous, s;ntered stainless steel and equipped with three 13 circumferential neoprene 0-rings. The piston-like electrode 2 was 14 coated with a silicone lubricant and inserted into the lower end of the tube 1. Ihe unlt was then weighed and set on a base for filling with 16 oil sand.
17 The tube 1 was packed with 6920 grams of oil sand containing18 14.9% bitumen and 1.6% water by weight. This was done by adding 350 gram 19 batches to the tube and packing them firmly with a steel rod. When loading was complete, the tube 1 contained a column of oil sand having a length 21 of 81 cms. The upper surface of the column was spaced about 5 cms. from 22 the upper end of the tube.
23 A layer of about 230 grams of 16 - 30 mesh size steel shot 24 was placed on the column of oil sand. This layer was saturated with 20 grams of water. Then 40 and 30 mesh stainless steel screens were laid 26 over the shot. An upper electrode 3, similar in construction to the 27 lower electrode and having a length of 4 cms., was inserted to complete 28 filling the tube 1.
1 The electrical and fluid lines were connected to the tube.2 Nitrogen was introduced into the outer vessel 4 to provide pressure of 3 500 psig Cooling water was circulated through the jacket 10 to attain 4 a ternperature of 10 + 1C.
Kerosene was injected into the base of the oil sand at a 6 rate of 30 cc/hr. for 4 hours. The rate was then reduced to 24 cc/hr.
7 and continued for a further 4 hours. As shown in Figure 2, the 8 injection pressure increased steadily.
9 A voltage of 750 A.C. was applied across the column for the last 3 hours of injection. The injection pressure decreased, as shown 11 in Figure 2.
8 Description of the Prior Art 9 The invention has been developed in connect;on with the tar sand of the Athabasca reservoir in Alberta, Canada. It has application 11 to other heavy oil reservoirs. However, it will be described below in 12 connection with such tar sand and the problems which characterize it.
13 Athabasca tar sand comprises unconsolidated or discrete 14 sand particles encapsulated in thin envelopes of water. The void spaces between the water-sheathed sand grains are filled with the 16 bitumen which is to be recovered. As a formation, the unheated tar 17 sand is relatively impermeable. Fluids, such as steam or flood solution, 18 cannot easily be injected into the formation. This difficulty is further 19 compounded by the relatively thin overburden (600' to 1200') overlying the formation. There is a likelihood that formation fracturing with the 21 use of high injection pressures will result.
22 One approach which has been investigated to get around these 23 problems has involved trying to first develop a narrow, permeable 24 interwell channel or path extending through the formation between the injection and production wells, using special techniques. Once this 26 channel is open and fluid communication between the wells exists, it 27 is then possible to inject steam into the channel. The injected steam 28 heats the bitumen around the channel. This now-mobile bitumen flows 29 into the channel and is driven to the production well. In this manner, 1 the channel is gradually widened and the formation bitumen may be 2 recovered.
3 One specific method previ.ously sugges.ted for developing 4 such a channel involves inject;ng a bitumen solvent, such as naphtha or kerosene, directly into the untreated reservoir. It would be antici-6 pated that the solvent would move through the formation through the 7 latter's water and gas phases and would reduce the viscosity of bitumen8 which it contacted, thereby mobilizing the bitumen. However, when this g method is practised, particularly wi.th formations having a relatively low water and gas saturation, it is frequently found that the injection 11 pressure gradually increases and eventually reaches an unacceptable 12 level, before breakthrough to the production well is achieved.
13 SUMMARY OF THE IN~ENTION
14 In accordance with the invention, it has been found that simultaneously applying electric current to the formation while injecting 16 a solvent for heavy oil provides an improved process for opening up a 17 fluid communication channel between injection and production points in a 18 previously unheated heavy oil reservoir. Solvent injection may be 19 continued until there is a breakthrough at the production well, or a smaller solvent slug may be followed with a drive fluid to force the 21 solvent as far as the production well.
22 Broadly stated, the invention is a method for opening a 23 fluid communication channel between injection and production wells in a24 previously unheated heavy oil reservoir, which comprises: injecting a solvent for the heavy oil into the reservoir; and, while solvent is 26 moving through the reservoir, passing electric current through the 27 reservoir between electrodes positioned in the injection and production28 wells.
1 DESCRIPTION OF THE DRAWI~G
2 Figure 1 is a schematic showing the laboratory apparatus 3 used to carry out the experiments reported hereinbelow.
4 Figure 2 is a plot showing the variation in injection pressure and oil sand temperature which occurs during solvent injection 6 without and with the application of electrical potential.
8 The solvent used is a low viscos;ty hydrocarbon which will g reduce the viscosity of the heavy oil or bitumen through solubili~ation and dilution when it contacts it. Suitable examples are naphtha, 11 kerosene,diesel and fuel oil, gas condensate and light crude.
12 The electrical current applied may be D.C. or A.C. In the case of D.C., it is preferred that the polarity of the electrode at the injection point be positive, with that at the production point being negative. An electroosmotic effect which assists in the penetration 16 of the solvent is obtained by this preferred D.C. arrangement.
17 The electrical current is applied concurrently with injection 18 of the solvent. This may be done throughout the solvent injection period19 or alternatively only during part of the period, when the injection pressure becomes high; the former is preferred, as it provides a con-21 tinuing directional influence on the advancing solvent.
22 Following breakthrough of the solvent at the production 23 point, one of a number of water based fluid drives may be used to cause 24 the solvent and bitumen to move to the production well. This provides for an early solvent-bitumen recovery and produces a more dependable 26 communication path for subsequent thermal methods.
27 The invention is exemplified by the following examples.
1 Experimental Apparatus 2 The experiments associated with this invention were carried 3 out in apparatus schematically shown ;n Figure 1. More particularly, 4 there was provided a fibrecast tube 1 having a length of 3 feet and inside d;ameter of 3 inches. This tube was packed with approximately 15 6 pounds of tar sand. Electrodes 2, 3 were provided in the form of floating 7 pistons, one being positioned in the tube at each end of the charge 8 Of tar sand. Each electrode was a cylindrical steel body having 0-ring g seals mounted in its outer surface~ The electrodes were adapted to slide within the tube when pressurized at their outer ends, while maintaining 11 the tube contents sealed.
12 The tube 1 was mounted in a cylindrical vessel 4. Pres-13 surized nitrogen could be supplied from a bottle 5 through line 6 to 14 the interior of the vessel 4. This nitrogen pressure would act to force the piston electrodes 2,3 inwardly, thereby compressing the tar 16 sand charge and simulating the application of overburden pressure.
17 Cold water and steam sources 7, 8 were connected by a 18 suitable valve and line system 9 to a jacket 10 surrounding the vessel 19 4. Thus the temperature of the vessel contents could be controlled.
A cylinder 11 containing a floating piston 12 was provided 21 to supply solvent or drive fluid through the line 13, extending 22 through the lower piston electrode 2, to the core. A water reservoir 2~ 14 was connected through the line 15 and metering pump 16 with the 24 lower end of the cylinder 11. Thus water could be pumped into the cylinder 11 to displace the floating p;ston 12 and force the charge of 26 solvent or drive fluid into the lower end of the tar sand column 17.
27 Electric power was supplied into vessel 4 by means of 28 ceramic feed-through devices 18 and the electrodes 2, 3, from an AC/DC
29 power source 19. The source 19 was capable of generating a variable voltage differential across the electrodes 2,3, of from 0 to 750 volts.
i51 1 A product line 20 connected with an outlet bore ~not shown) 2 extending through the upper electrode 3, delivered production to a glass 3 receiver 21.
This example demonstrated that cold solvent injection would 6 enter tar sand and initiate a communications path. However pressure 7 differential build-up did occur; th;s differential was reduced when 8 electrical assist was employed and communication between injection and 9 production points was successfully re-established and maintained.
The 3" diameter fibrecast tube 1 was first equipped at 11 its lower end with the electrode 2. This electrode was one faced with a 12 1/8" thickness of porous, s;ntered stainless steel and equipped with three 13 circumferential neoprene 0-rings. The piston-like electrode 2 was 14 coated with a silicone lubricant and inserted into the lower end of the tube 1. Ihe unlt was then weighed and set on a base for filling with 16 oil sand.
17 The tube 1 was packed with 6920 grams of oil sand containing18 14.9% bitumen and 1.6% water by weight. This was done by adding 350 gram 19 batches to the tube and packing them firmly with a steel rod. When loading was complete, the tube 1 contained a column of oil sand having a length 21 of 81 cms. The upper surface of the column was spaced about 5 cms. from 22 the upper end of the tube.
23 A layer of about 230 grams of 16 - 30 mesh size steel shot 24 was placed on the column of oil sand. This layer was saturated with 20 grams of water. Then 40 and 30 mesh stainless steel screens were laid 26 over the shot. An upper electrode 3, similar in construction to the 27 lower electrode and having a length of 4 cms., was inserted to complete 28 filling the tube 1.
1 The electrical and fluid lines were connected to the tube.2 Nitrogen was introduced into the outer vessel 4 to provide pressure of 3 500 psig Cooling water was circulated through the jacket 10 to attain 4 a ternperature of 10 + 1C.
Kerosene was injected into the base of the oil sand at a 6 rate of 30 cc/hr. for 4 hours. The rate was then reduced to 24 cc/hr.
7 and continued for a further 4 hours. As shown in Figure 2, the 8 injection pressure increased steadily.
9 A voltage of 750 A.C. was applied across the column for the last 3 hours of injection. The injection pressure decreased, as shown 11 in Figure 2.
Claims
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method for opening a fluid communication channel between injection and production wells in a previously unheated heavy oil reservoir wherein the oil is not amenable to being produced by a drive fluid, which comprises:
injecting a hydrocarbon solvent into the reservoir;
and simultaneously passing electric current through that portion of the reservoir containing the solvent, said current passing between electrodes positioned in the injection wells, said anode electrode being located in the injection well and said cathode electrode being located in the production well, whereby the current assists in directing the advance of the solvent to the production well.
injecting a hydrocarbon solvent into the reservoir;
and simultaneously passing electric current through that portion of the reservoir containing the solvent, said current passing between electrodes positioned in the injection wells, said anode electrode being located in the injection well and said cathode electrode being located in the production well, whereby the current assists in directing the advance of the solvent to the production well.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000388179A CA1166151A (en) | 1981-10-19 | 1981-10-19 | Combination solvent injection-electric current application method for establishing fluid communication through heavy oil formation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000388179A CA1166151A (en) | 1981-10-19 | 1981-10-19 | Combination solvent injection-electric current application method for establishing fluid communication through heavy oil formation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1166151A true CA1166151A (en) | 1984-04-24 |
Family
ID=4121191
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000388179A Expired CA1166151A (en) | 1981-10-19 | 1981-10-19 | Combination solvent injection-electric current application method for establishing fluid communication through heavy oil formation |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1166151A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1989009664A2 (en) * | 1988-04-14 | 1989-10-19 | Battelle Memorial Institute | In situ heating to detoxify organic-contaminated soils |
| CN105717255A (en) * | 2016-01-27 | 2016-06-29 | 中国石油天然气股份有限公司 | Complex solvent soaking huff and puff circulation experimental device and simulation mining method |
-
1981
- 1981-10-19 CA CA000388179A patent/CA1166151A/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1989009664A2 (en) * | 1988-04-14 | 1989-10-19 | Battelle Memorial Institute | In situ heating to detoxify organic-contaminated soils |
| WO1989009664A3 (en) * | 1988-04-14 | 1990-01-25 | Battelle Memorial Institute | In situ heating to detoxify organic-contaminated soils |
| US4957393A (en) * | 1988-04-14 | 1990-09-18 | Battelle Memorial Institute | In situ heating to detoxify organic-contaminated soils |
| US5316411A (en) * | 1988-04-14 | 1994-05-31 | Battelle Memorial Institute | Apparatus for in situ heating and vitrification |
| CN105717255A (en) * | 2016-01-27 | 2016-06-29 | 中国石油天然气股份有限公司 | Complex solvent soaking huff and puff circulation experimental device and simulation mining method |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |