CN112324407A - Method and device for researching steam cavity expansion boundary in SAGD development process - Google Patents
Method and device for researching steam cavity expansion boundary in SAGD development process Download PDFInfo
- Publication number
- CN112324407A CN112324407A CN202011299792.9A CN202011299792A CN112324407A CN 112324407 A CN112324407 A CN 112324407A CN 202011299792 A CN202011299792 A CN 202011299792A CN 112324407 A CN112324407 A CN 112324407A
- Authority
- CN
- China
- Prior art keywords
- oil
- pipe
- steam
- shell
- production
- 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.)
- Pending
Links
- 238000010796 Steam-assisted gravity drainage Methods 0.000 title claims abstract description 65
- 238000000034 method Methods 0.000 title claims abstract description 45
- 238000011161 development Methods 0.000 title claims abstract description 41
- 230000008569 process Effects 0.000 title claims abstract description 32
- 239000003921 oil Substances 0.000 claims abstract description 174
- 238000004519 manufacturing process Methods 0.000 claims abstract description 114
- 239000010779 crude oil Substances 0.000 claims abstract description 48
- 239000011229 interlayer Substances 0.000 claims abstract description 44
- 238000004088 simulation Methods 0.000 claims abstract description 38
- 238000010793 Steam injection (oil industry) Methods 0.000 claims abstract description 37
- 238000002347 injection Methods 0.000 claims abstract description 34
- 239000007924 injection Substances 0.000 claims abstract description 34
- 238000002474 experimental method Methods 0.000 claims abstract description 17
- 239000010410 layer Substances 0.000 claims abstract description 17
- 230000035699 permeability Effects 0.000 claims abstract description 15
- 238000003860 storage Methods 0.000 claims abstract description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 23
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 16
- 238000001514 detection method Methods 0.000 claims description 15
- 239000003027 oil sand Substances 0.000 claims description 15
- 239000006004 Quartz sand Substances 0.000 claims description 13
- 239000003292 glue Substances 0.000 claims description 12
- 239000003822 epoxy resin Substances 0.000 claims description 11
- 229920000647 polyepoxide Polymers 0.000 claims description 11
- 239000007788 liquid Substances 0.000 claims description 10
- 239000000203 mixture Substances 0.000 claims description 10
- 238000011084 recovery Methods 0.000 claims description 9
- 239000004927 clay Substances 0.000 claims description 8
- 239000000523 sample Substances 0.000 claims description 7
- 229920006395 saturated elastomer Polymers 0.000 claims description 7
- 238000012545 processing Methods 0.000 claims description 6
- 238000010438 heat treatment Methods 0.000 claims description 4
- 238000007789 sealing Methods 0.000 claims description 4
- 238000010586 diagram Methods 0.000 description 10
- 239000000295 fuel oil Substances 0.000 description 7
- 239000000945 filler Substances 0.000 description 6
- 238000005192 partition Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 239000004576 sand Substances 0.000 description 3
- 239000002569 water oil cream Substances 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 230000001186 cumulative effect Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 239000010426 asphalt Substances 0.000 description 1
- 238000004523 catalytic cracking Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 238000004945 emulsification Methods 0.000 description 1
- 229920006335 epoxy glue Polymers 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000000813 microbial effect Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Images
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
- E21B43/2406—Steam assisted gravity drainage [SAGD]
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09B—EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS
- G09B25/00—Models for purposes not provided for in G09B23/00, e.g. full-sized devices for demonstration purposes
- G09B25/02—Models for purposes not provided for in G09B23/00, e.g. full-sized devices for demonstration purposes of industrial processes; of machinery
Abstract
The invention discloses a method and a device for researching steam expansion boundary in SAGD development process, comprising an SAGD three-dimensional experiment simulation system, a steam supply unit, an oil supply unit and a collection unit; the SAGD three-dimensional experimental simulation system comprises a shell, an interlayer forming mold, a first oil injection pipe, a first oil production pipe, a second oil injection pipe, a second oil production pipe, a steam injection pipe and a production pipe; the interlayer forming mold is detachably arranged in the shell and used for forming an interlayer with required permeability in the shell and then removing the interlayer, and the interlayer divides the interior of the shell into an upper crude oil reservoir and a lower crude oil reservoir; the first oil injection pipe and the second oil production pipe are arranged in the upper crude oil storage layer, and the second oil injection pipe, the second oil production pipe, the steam injection pipe and the production pipe are arranged in the lower crude oil storage layer; the steam supply unit is connected with the steam injection pipe; the oil supply unit is connected with the first oil filling pipe and the second oil filling pipe; the first oil production pipe, the second oil production pipe and the production pipe are all connected with the collecting unit.
Description
Technical Field
The invention relates to a device and a method for researching steam cavity expansion boundary in an SAGD development process, and belongs to the technical field of SAGD exploitation.
Background
With the increasing shortage of global conventional oil and gas resources, the increasing demand of oil and gas resources and the decreasing of the yield of conventional crude oil, the development of thickened oil is gradually paid attention. The oil sand serving as an unconventional oil and gas resource can become an important component of future oil and gas resources, the heavy oil exploitation has very urgent practical significance for relieving the shortage of energy supply and demand, and the importance of efficiently developing heavy oil reservoirs is self-evident.
In the development process of heavy oil reservoir, many effective oil recovery methods are generated, including thermal recovery method, microbial heavy oil recovery technology, light oil dilution viscosity reduction, emulsification viscosity reduction method, catalytic cracking and the like. The most economic enhanced oil recovery method for producing super heavy oil and asphalt is Steam-Assisted Gravity Drainage (SAGD), which is a novel heavy oil production mode and can provide higher crude oil recovery rate besides a series of advantages of high oil displacement efficiency, high oil production speed, large development volume of a Steam cavity and the like.
The physical interlayer (interlayer for short) is widely developed in an actual oil reservoir, and the SAGD development effect is seriously influenced. The conventional SAGD experiment mainly aims at researching the change of a temperature field and the development of a steam cavity under the condition of no interlayer, and does not aim at researching the development of the temperature field and the expansion limit of the steam cavity when the interlayer exists.
Disclosure of Invention
In view of the above problems, it is an object of the present invention to provide a method and apparatus for studying steam chamber expansion limits in SAGD development processes.
In order to achieve the purpose, the invention adopts the following technical scheme: a device for researching a steam expansion boundary in an SAGD development process comprises an SAGD three-dimensional experiment simulation system, a steam supply unit, an oil supply unit and a collection unit;
the SAGD three-dimensional experimental simulation system comprises a shell, an interlayer forming mold, a first oil injection pipe, a first oil production pipe, a second oil injection pipe, a second oil production pipe, a steam injection pipe and a production pipe; the interlayer forming die is detachably arranged in the shell and used for being detached after an interlayer with required permeability is formed in the shell, and the interlayer divides the interior of the shell into an upper crude oil reservoir and a lower crude oil reservoir; the first oil injection pipe and the first oil production pipe are arranged in the upper crude oil storage layer, and the second oil injection pipe, the second oil production pipe, the steam injection pipe and the production pipe are arranged in the lower crude oil storage layer;
the steam supply unit is connected with the steam injection pipe; the oil supply unit is connected with the first oil filling pipe and the second oil filling pipe; the first oil production pipe, the second oil production pipe and the production pipe are all connected with the collecting unit.
In some embodiments, the steam supply unit includes a first driving pump, a water container, and a superheated steam generator, the first driving pump is connected to the water container, an output end of the water container is connected to a liquid inlet end of the superheated steam generator, and an exhaust end of the superheated steam generator is connected to the steam injection pipe.
In some embodiments, the exhaust end of the superheated steam generator is connected with an air inlet pipeline, the air inlet pipeline comprises a first branch pipeline and a second branch pipeline which are connected in parallel, the first branch pipeline is connected with the steam injection pipe, and the second branch pipeline is spirally wound outside the steam injection pipe and the production pipe and used for heating oil reservoirs around the steam injection pipe and the production pipe;
a first pressure gauge is arranged between the superheated steam generator and the steam injection pipe.
In some embodiments, the oil supply unit includes a first drive pump connected to the oil container, and an oil container connected to the first and second filler pipes.
In some embodiments, the collection unit comprises a first collector, a second collector, a back pressure valve, and a condenser; the first collector is connected with the first oil production pipe and the second oil production pipe; the second collector is connected with the production pipe, and the back pressure valve and the condenser are arranged between the production pipe and the second collector.
In some embodiments, the back pressure valve is connected to a hand pump for pressurizing the back pressure valve; and a third pressure gauge is arranged on the hand pump.
In some embodiments, the first filler pipe is disposed in an upper portion of an upper crude oil reservoir and the second filler pipe is disposed in an upper portion of a lower crude oil reservoir; the first production tubing is disposed in a lower portion of an upper crude reservoir and the second production tubing is disposed in a lower portion of a lower crude reservoir.
In some embodiments, the apparatus further comprises a control system comprising a computer system; a plurality of temperature detection devices are uniformly arranged on the inner wall of the shell, the temperature detection devices adopt temperature probes, and the temperature probes are connected with the computer system; the device includes insulating layer, thermostated container and second pressure gauge, and the second pressure gauge sets up the inside of casing, the insulating layer sets up the outside of casing, the casing is placed in the thermostated container.
Additionally, the invention also provides a method for researching the expansion limit of the steam cavity in the SAGD development process based on the device in any embodiment, which comprises the following steps:
1) quartz sand and epoxy resin glue are uniformly mixed, then the mixture is filled into an interlayer forming die for curing, the interlayer forming die is removed after the curing is finished, and a plurality of temperature detection devices are uniformly distributed on the inner wall of the shell; filling the uniformly mixed oil sand into an upper crude oil reservoir and a lower crude oil reservoir in the shell; uniformly mixing clay and water, and then uniformly paving the mixture on the upper part of the oil sand; completely covering the oil sand without gaps; to ensure the sealing performance of the shell, a flat shovel is used for processing the covered clay layer to be smooth;
2) placing the shell in a thermostat, well connecting a steam supply unit with a steam injection pipe, an oil supply unit with a first oil injection pipe and a second oil injection pipe, and a collection unit with a first oil production pipe, a second oil production pipe and a production pipe, wherein a temperature detection device is connected with a control system, and the control system comprises a computer system;
3) setting the constant temperature box to a preset temperature, and injecting crude oil into the shell by the oil supply unit to enable the shell to reach a set initial oil saturation degree; the total oil injection amount of the first oil injection pipe and the second oil injection pipe is calculated to subtract the oil production amounts of the first oil production pipe and the second oil production pipe, and the oil amount in the oil sand in the step 2) is added, namely the oil amount saturated into the shell;
4) closing the oil supply unit, opening the steam supply unit, injecting steam into the shell from the steam injection pipe, collecting temperature data in the shell by the temperature detection device, transmitting the temperature data to the control system, and processing the obtained temperature data by the control system to obtain the development process of the steam cavity; the collecting unit collects the crude oil discharged by the first oil production pipe and the second oil production pipe and the produced liquid discharged by the production pipes, and further calculates the accumulated oil production rate, the accumulated oil production and the recovery ratio;
5) when the production pipe does not discharge liquid any more, the experiment is ended, the steam supply unit and the constant temperature box are closed, the pressure in the shell is released to 0, and the shell is opened to observe the expansion rule of the steam cavity.
In some embodiments, the mass ratio of the quartz sand to the epoxy resin glue in the step 1) is 0.16-0.12, and the initial oil saturation is set to be 85% in the step 4).
By adopting the technical scheme, the invention has the following advantages: the device for researching the steam cavity expansion boundary in the SAGD development process comprises an SAGD three-dimensional experiment simulation system, a steam supply unit, an oil supply unit and a collection unit, interlayers with different permeabilities and thicknesses can be prepared through a detachable interlayer die in the SAGD three-dimensional experiment simulation system, the steam supply unit, the oil supply unit and the collection unit are matched, the actual oil production environment of an SAGD technology can be accurately simulated, the steam cavity expansion boundary and the temperature field change rule are accurately represented in the steam assisted gravity drainage process, the problem that the expansion boundary of a steam cavity in the steam assisted gravity drainage process of a heavy oil reservoir cannot be tested by a conventional method is solved, and the macroscopic description of the steam cavity expansion boundary in the steam assisted gravity drainage process becomes possible; theoretical and technical support is provided for further optimizing steam cavity expansion and improving the oil production effect of the SAGD technology.
Drawings
FIG. 1 is a schematic diagram of an apparatus for studying steam chamber expansion limits in a SAGD development process provided by an embodiment of the present invention;
FIG. 2 is a schematic structural view of an injection pipe and a production pipe in a three-dimensional experimental simulation system for SAGD according to a first embodiment of the present invention;
FIG. 3 is a schematic cross-sectional structure diagram of a SAGD three-dimensional experimental simulation system in the first embodiment of the present invention;
FIG. 4 is a graphical representation of the permeability of the interlayer as a function of the mass ratio of the quartz sand to the epoxy glue;
FIG. 5 is a schematic diagram of the development of the steam cavity when the SAGD three-dimensional experimental simulation device is heated for 400 min;
FIG. 6 is a schematic diagram of the development of the steam cavity when the SAGD three-dimensional experimental simulation device is heated for 1000 min;
FIG. 7 is a schematic diagram of the development of a steam cavity when the SAGD three-dimensional experimental simulation device is heated for 1500 min;
FIG. 8 is a schematic diagram of the development of the steam cavity when the SAGD three-dimensional experimental simulation device is heated for 2100 min.
Detailed Description
The invention is described in detail below with reference to the figures and examples. It is to be understood, however, that the drawings are provided solely for the purposes of promoting an understanding of the invention and that they are not to be construed as limiting the invention.
Example one
As shown in fig. 1 and fig. 3, the present embodiment provides a device for researching steam expansion boundary in SAGD development process, including a SAGD three-dimensional experimental simulation system 1, a steam supply unit 2, an oil supply unit 3 and a collection unit 4;
the SAGD three-dimensional experimental simulation system 1 comprises a shell 11, a sandwich layer forming mold 12, a first oil injection pipe 13, a first oil production pipe 14, a second oil injection pipe 15, a second oil production pipe 16, a steam injection pipe 17 and a production pipe 18; the interlayer forming die 12 is detachably arranged in the shell 11 and is used for forming an interlayer with required permeability in the shell 11 and then removing the interlayer, and the interlayer divides the interior of the shell 11 into an upper crude oil reservoir 111 and a lower crude oil reservoir 112; a first injection pipe 13 and a first production pipe 14 are disposed in the upper crude oil reservoir 111, and a second injection pipe 15, a second production pipe 16, a steam injection pipe 17 and a production pipe 18 are disposed in the lower crude oil reservoir 112;
the steam supply unit 2 is connected with a steam injection pipe 17 and is used for introducing steam into the shell 11; the oil supply unit 3 is connected with the first oil injection pipe 13 and the second oil injection pipe 15 and is used for introducing crude oil into the shell 11; the first production tubing 14, the second production tubing 16 and the production tubing 18 are all connected to a collection unit 4, the collection unit 4 being used for collecting produced fluids as well as supersaturated crude oil.
In the above embodiment, preferably, the steam supply unit 2 includes a first driving pump 21, a water container 22 and a superheated steam generator 23, the driving pump 21 is connected to the water container 22, an output end of the water container 22 is connected to a liquid inlet end of the superheated steam generator 23, a gas outlet end of the superheated steam generator 23 is connected to the steam injection pipe 17, the driving pump 21 drives water in the water container 22 to enter the superheated steam generator 23, and the superheated steam generator 23 converts the water into steam and introduces the steam into the SAGD three-dimensional experimental simulation system 1.
In the above embodiment, preferably, as shown in fig. 2, the exhaust end of the superheated steam generator 23 is connected to the intake line 5, the intake line 5 includes a first branch line and a second branch line connected in parallel with each other, the first branch line is connected to the steam injection pipe 17, and the second branch line is spirally wound outside the steam injection pipe 17 and the production pipe 18 for heating the reservoir temperature around the steam injection pipe 17 and the production pipe 18.
In the above embodiment, preferably, a first pressure gauge is arranged between the superheated steam generator 4 and the steam injection pipe 17, namely, a first pressure gauge is arranged on the air inlet pipeline 5, the range of the first pressure gauge is 50MPa, and the accuracy of the first pressure gauge is 0.50MPa, and the first pressure gauge is used for monitoring the steam pressure entering the SAGD three-dimensional experimental simulation system 1.
In the above embodiment, preferably, the oil supply unit 3 includes the first drive pump 31 and the oil container 32, the first drive pump 31 is connected to the oil container 32, and the oil container 32 is connected to the first and second filler pipes 13 and 15.
In the above embodiment, it is preferable that the steam supply unit 2 and the oil supply unit 3 may share one driving pump, and the driving pump is a constant-speed constant-pressure pump.
In the above embodiment, preferably, the collection unit 4 includes the first collector 41, the second collector 42, the back-pressure valve 43, and the condenser 44; a first collector 41 is connected to the first production tubing 14 and the second production tubing 16 for collecting supersaturated crude oil in the upper crude oil reservoir 111 and the lower crude oil reservoir 112; a second accumulator 42 is connected to the production tubing 18 for accumulating production fluid produced by the production tubing 18, and a back pressure valve 43 and a condenser 44 are disposed between the production tubing 18 and the second accumulator 42.
In the above embodiment, preferably, the back pressure valve 43 is connected to a hand pump for pressurizing the back pressure valve 43; a third pressure gauge is arranged on the hand pump and used for controlling the pressure of the back pressure valve 43, the measuring range of the third pressure gauge is 50MPa, and the precision is 0.50 MPa; the setting of the third pressure gauge can clearly control the experiment pressure, so that the experiment pressure is consistent with the field pressure.
In the above embodiment, preferably, the first filler pipe 13 is provided in the upper portion of the upper crude oil reservoir 111, and the second filler pipe 15 is provided in the upper portion of the lower crude oil reservoir 112; a first production tubing 14 is disposed in the lower portion of the upper crude reservoir 111 and a second production tubing 16 is disposed in the lower portion of the lower crude reservoir 112; the oil filling pipe and the oil production pipe are arranged in positions, so that the experimental simulation system can be better saturated with oil and water.
In the above embodiment, preferably, as shown in fig. 3, a plurality of temperature detecting devices 6 are uniformly arranged on the inner wall of the housing 11, the temperature detecting devices 6 can be temperature probes, in this embodiment, the housing 11 is a cuboid with a length of 50cm and a width of 40cm, and the distance between two adjacent temperature detecting devices 6 is 5 cm.
In the above embodiment, preferably, the device includes a heat insulation layer and an incubator (not shown in the figure), the heat insulation layer is disposed outside the housing 11, the housing 11 is placed in the incubator, the temperature of the incubator can be set to 80 ℃, when the SAGD three-dimensional experimental simulation system 1 simulates saturated oil, the incubator is required to heat the experimental simulation system 1 to 80 ℃, and at the temperature of 80 ℃, the viscosity of the thick oil is reduced, and the thick oil has very good fluidity, so that the crude oil in the experimental simulation system 1 can be fully saturated.
In the above embodiment, it is preferable that a second pressure gauge for collecting the internal pressure of the housing 11 be provided in the housing 11.
In the above embodiment, preferably, the apparatus further includes a control system 7, where the control system 7 includes a computer system, and is connected to the temperature detection device 6, the first pressure gauge, the second pressure gauge, and the third pressure gauge, and receives temperature data and pressure data inside the SAGD three-dimensional experimental simulation system 1 during the experimental process collected by the temperature detection device 6 and the second pressure gauge, pressure data collected by the third pressure gauge at the production end of the production pipe 18, and pressure data collected by the first pressure gauge at the injection end of the steam injection pipe 17; and drawing an isothermal line in the simulation system 1 according to the acquired temperature data, analyzing the temperature field in the simulation system and displaying an image.
Example two
Additionally, based on the apparatus for researching steam cavity extension boundary in SAGD development process in any of the above embodiments, the present invention also provides a method for researching steam cavity extension boundary in SAGD development process, which includes the following steps:
1) quartz sand and epoxy resin glue are uniformly mixed, then the mixture is filled into an interlayer forming die 12 for curing, the interlayer forming die 12 is removed after the curing is finished, so that an interlayer is prepared in the shell 11, and a plurality of temperature detection devices 6 are uniformly distributed on the inner wall of the shell 11;
2) filling the well-mixed oil sands into an upper crude oil reservoir 111 and a lower crude oil reservoir 112 within the casing 11;
3) uniformly mixing clay and water, and then uniformly paving the mixture on the upper part of the oil sand; completely covering the oil sand without gaps; to ensure the sealing performance of the shell 11, the covered clay layer is processed to be smooth by a flat shovel;
4) placing a shell 11 in a thermostat, well connecting a steam supply unit 2 with a steam injection pipe 17, an oil supply unit 3 with a first oil injection pipe 13 and a second oil injection pipe 15, and a collection unit 4 with a first oil production pipe 14, a second oil production pipe 16 and a production pipe 18, connecting a temperature detection device 6 with a control system 7, wherein the control system 7 comprises a computer system;
5) setting the thermostat to a preset temperature, and injecting crude oil into the shell 11 by the oil supply unit 3 to enable the interior of the shell 11 to reach a set initial oil saturation degree; calculating the total oil filling amount of the first oil filling pipe 13 and the second oil filling pipe 15 minus the oil production amounts of the first oil production pipe 14 and the second oil production pipe 16, and adding the oil amount in the oil sand in the step 2), namely the oil amount saturated into the shell 11;
6) closing the oil supply unit 3, opening the steam supply unit 2, injecting steam into the shell 11 from the steam injection pipe 17, collecting temperature data in the shell 11 by the temperature detection device 6, transmitting the temperature data to the control system 7, and processing the obtained temperature data by the control system 7 to obtain the development process of the steam cavity; the collecting unit 4 collects the crude oil discharged through the first oil production pipe 14 and the second oil production pipe 15 and the produced liquid (oil-water emulsion) discharged through the production pipe 18, and further calculates the cumulative oil production rate, the cumulative oil production amount and the recovery ratio;
7) when the production pipe 18 does not discharge liquid any more, the experiment is ended, the steam supply unit 2 and the thermostat are closed, the pressure in the shell 11 is relieved to 0, and the shell 11 is opened to observe the expansion rule of the steam cavity.
Further, the quartz sand and the epoxy resin glue are mixed according to different mass ratios to obtain interlayers with different permeabilities, the interlayers with different permeabilities can influence the expansion of the steam chamber, the relationship between the mass ratio of the quartz sand to the epoxy resin glue and the permeability (as shown in fig. 4) is that in the step 1), the mass ratio of the quartz sand to the epoxy resin glue is 0.16-0.12.
Further, in the step 2), the inner volume of the shell 11 can be filled with the mass of the quartz sand, and the mass ratio of the crude oil to the water meets the original oil saturation of the oil reservoir by 85%.
Further, in step 4), the initial oil saturation was set to 85%.
The method of use of the device according to the invention is described below with reference to a specific example
1) Quartz sand and epoxy resin glue are uniformly mixed, then the mixture is filled into an interlayer forming die 12 for curing, and the interlayer forming die 12 is removed after the curing is finished, so that an interlayer is prepared;
flatly placing a shell 11, selecting a partition plate as an interlayer forming die 12, placing the partition plate in the shell 11, selecting sand with a corresponding proportion of 320 meshes to mix according to the interlayer permeability, weighing 50g each time, putting the mixture into a disposable paper cup, adding epoxy resin glue with the mass fraction of 6% (A, B glue proportion is 1: 1), uniformly stirring, filling the mixture into the partition plate, and compacting by using a sand filling device; after curing for 24h, the partition plate was removed, and the mass ratio of the epoxy resin glue to the quartz sand in this example was 0.12, resulting in a sandwich permeability of 20mD and a sandwich thickness of 2 cm.
(2) Filling the well-mixed oil sands into an upper crude oil reservoir 111 and a lower crude oil reservoir 112 within the casing 11;
wherein, for an interlayer with a permeability of 20mD and a thickness of 2cm, the ratio of quartz sand, oil and water is as shown in Table 1:
TABLE 1
I.e. to fill the upper 111 and lower 112 crude oil reservoirs, 2770g crude oil mass, 498g water mass, 17575g total sand filled mass is required.
3) Uniformly mixing clay and water, and then uniformly paving the mixture on the upper part of the oil sand; completely covering the oil sand without gaps; to ensure the sealing performance of the shell 11, the covered clay layer is processed to be smooth by a flat shovel;
4) connecting a device for researching the expansion limit of the steam cavity in the SAGD development process, opening a switch of the oil container 32, a constant-speed constant-pressure pump and a constant-temperature box, and injecting crude oil into the SAGD three-dimensional experiment simulation system 1 to enable the SAGD three-dimensional experiment simulation system 1 to reach the set initial oil saturation; the total amount of oil injected from the first and second oil injection pipes 13 and 15 is calculated minus the amount of oil produced from the first and second oil production pipes 14 and 16, plus the amount of oil in the oil sand in step 2), which is the amount of oil saturated into the housing 11.
Wherein the set initial oil saturation is 85%; the oil injection speed of the constant-speed constant-pressure pump 1 is set to be 16mL/min, and the pressure range of the constant-speed constant-pressure pump 1 is 0.001-60 MPa.
5) Closing an oil container 32 switch, opening the water container 22 and the constant-speed constant-pressure pump, and supplying water into the superheated steam generator 23; turning on the superheated steam generator 23, setting the temperature of the steam discharged from the superheated steam generator 23;
wherein the water supply speed of the constant-speed constant-pressure pump is 0.001-60 mL/min, and the pressure range of the constant-speed constant-pressure pump is 0.001-60 MPa; the temperature of the discharged steam set by the superheated steam generator 23 is 280-300 ℃;
6) steam is injected into the SAGD three-dimensional experiment simulation system 1 from the steam injection pipe 17, temperature data are obtained through a temperature probe inside the SAGD three-dimensional experiment simulation system 1, the temperature data obtained by the temperature probe are transmitted to a computer, a steam cavity development process is obtained through data processing in the computer, an oil-water emulsion discharged by the production pipe 18 sequentially passes through a back pressure valve 43 and a condenser 44 and then is collected into a second collector 42, and the oil-water emulsion is dried and then weighed; finally, calculating the accumulative oil production rate, the accumulative oil production and the recovery ratio;
7) when the liquid is not discharged from the production end of the production pipe 18 any more, the experiment is finished, the constant-speed constant-pressure pump, the superheated steam generator 23 and the constant temperature box are closed, the back pressure valve 43 is set to be 0Mpa, the pressure is released from the production pipe 18, the pressure of the SAGD three-dimensional experiment simulation system 1 is released to 0, and the SAGD three-dimensional experiment simulation system 1 is opened to observe the expansion rule of the steam cavity.
FIG. 5 is a development diagram of a steam cavity when a SAGD three-dimensional experimental simulation system is heated for 400min, and the temperature contour is 62-110 ℃ from outside to inside; FIG. 6 is a development diagram of a steam cavity when the SAGD three-dimensional experimental simulation system is heated for 1000min, and the isotherm is from outside to inside from 70 ℃ to 110 ℃; FIG. 7 is a development diagram of a steam cavity when a SAGD three-dimensional experimental simulation system is heated for 1500min, and the temperature contour is 70-130 ℃ from outside to inside; FIG. 8 is a development diagram of a steam cavity when a SAGD three-dimensional experimental simulation system is heated for 2100min, and the isotherm is 62 ℃ to 180 ℃ from outside to inside.
The heating time in fig. 5 to 8 is calculated by starting steam injection from the steam injection pipe 17 to the SAGD three-dimensional experimental simulation system 1, and the black horizontal line in fig. 5 to 8 is the position of the interlayer and is located at the height of the shell 2/3 of the SAGD three-dimensional experimental simulation system 1. As can be seen from FIGS. 5 to 8, the steam chamber develops faster in the longitudinal direction and expands slower in the lateral direction due to the steam overlap effect, and the steam chamber is elongated before reaching the top end of the housing 11. At 400min the steam cavity expanded to the height of the model 2/3 (at the sandwich), and due to the ultra-low permeability of the sandwich, the steam cavity first expanded laterally along the sandwich. After 2100min, the steam chamber could not break through the interlayer all the time due to the obstruction of the ultra-low permeability interlayer, and only heat broke through the interlayer. Thus, the development process of the steam cavity is obtained when the interlayer with the permeability of 20mD and the thickness of 2cm is obtained.
The present invention has been described with reference to the above embodiments, and the structure, arrangement, and connection of the respective members may be changed. On the basis of the technical scheme of the invention, the improvement or equivalent transformation of the individual components according to the principle of the invention is not excluded from the protection scope of the invention.
Claims (10)
1. An apparatus for studying steam expansion limits in a SAGD development process, characterized by: the SAGD three-dimensional experimental simulation system comprises an SAGD three-dimensional experimental simulation system, a steam supply unit, an oil supply unit and a collection unit;
the SAGD three-dimensional experimental simulation system comprises a shell, an interlayer forming mold, a first oil injection pipe, a first oil production pipe, a second oil injection pipe, a second oil production pipe, a steam injection pipe and a production pipe; the interlayer forming die is detachably arranged in the shell and used for being detached after an interlayer with required permeability is formed in the shell, and the interlayer divides the interior of the shell into an upper crude oil reservoir and a lower crude oil reservoir; the first oil injection pipe and the first oil production pipe are arranged in the upper crude oil storage layer, and the second oil injection pipe, the second oil production pipe, the steam injection pipe and the production pipe are arranged in the lower crude oil storage layer;
the steam supply unit is connected with the steam injection pipe; the oil supply unit is connected with the first oil filling pipe and the second oil filling pipe; the first oil production pipe, the second oil production pipe and the production pipe are all connected with the collecting unit.
2. The apparatus for studying steam expansion limits in a SAGD development process of claim 1, wherein: the steam supply unit comprises a first drive pump, a water container and a superheated steam generator, the first drive pump is connected with the water container, the output end of the water container is connected with the liquid inlet end of the superheated steam generator, and the exhaust end of the superheated steam generator is connected with the steam injection pipe.
3. The apparatus for studying steam expansion limits in a SAGD development process of claim 2, wherein: the exhaust end of the superheated steam generator is connected with an air inlet pipeline, the air inlet pipeline comprises a first branch pipeline and a second branch pipeline which are connected in parallel, the first branch pipeline is connected with the steam injection pipe, and the second branch pipeline is spirally wound outside the steam injection pipe and the production pipe and used for heating oil reservoirs around the steam injection pipe and the production pipe;
a first pressure gauge is arranged between the superheated steam generator and the steam injection pipe.
4. The apparatus for studying steam expansion limits in a SAGD development process of claim 1, wherein: the oil supply unit comprises a first driving pump and an oil container, the first driving pump is connected with the oil container, and the oil container is connected with a first oil filling pipe and a second oil filling pipe.
5. The apparatus for studying steam expansion limits in a SAGD development process of claim 1, wherein: the collecting unit comprises a first collector, a second collector, a back pressure valve and a condenser; the first collector is connected with the first oil production pipe and the second oil production pipe; the second collector is connected with the production pipe, and the back pressure valve and the condenser are arranged between the production pipe and the second collector.
6. The apparatus for studying steam expansion limits in a SAGD development process of claim 5, wherein: the back pressure valve is connected with the hand pump, and the hand pump is used for pressurizing the back pressure valve; and a third pressure gauge is arranged on the hand pump.
7. The apparatus for studying steam expansion limits in a SAGD development process of claim 1, wherein: the first oil filling pipe is arranged at the upper part of the upper crude oil reservoir, and the second oil filling pipe is arranged at the upper part of the lower crude oil reservoir; the first production tubing is disposed in a lower portion of an upper crude reservoir and the second production tubing is disposed in a lower portion of a lower crude reservoir.
8. The apparatus for studying steam expansion limits in a SAGD development process of claim 1, wherein: the apparatus also includes a control system including a computer system; a plurality of temperature detection devices are uniformly arranged on the inner wall of the shell, the temperature detection devices adopt temperature probes, and the temperature probes are connected with the computer system; the device includes insulating layer, thermostated container and second pressure gauge, and the second pressure gauge sets up the inside of casing, the insulating layer sets up the outside of casing, the casing is placed in the thermostated container.
9. A method for researching the expansion limit of a steam cavity in the SAGD development process based on the device of any one of claims 1 to 8, is characterized by comprising the following steps:
1) quartz sand and epoxy resin glue are uniformly mixed, then the mixture is filled into an interlayer forming die for curing, the interlayer forming die is removed after the curing is finished, and a plurality of temperature detection devices are uniformly distributed on the inner wall of the shell; filling the uniformly mixed oil sand into an upper crude oil reservoir and a lower crude oil reservoir in the shell; uniformly mixing clay and water, and then uniformly paving the mixture on the upper part of the oil sand; completely covering the oil sand without gaps; to ensure the sealing performance of the shell, a flat shovel is used for processing the covered clay layer to be smooth;
2) placing the shell in a thermostat, well connecting a steam supply unit with a steam injection pipe, an oil supply unit with a first oil injection pipe and a second oil injection pipe, and a collection unit with a first oil production pipe, a second oil production pipe and a production pipe, wherein a temperature detection device is connected with a control system, and the control system comprises a computer system;
3) setting the constant temperature box to a preset temperature, and injecting crude oil into the shell by the oil supply unit to enable the shell to reach a set initial oil saturation degree; measuring the total oil injection amount of the first oil injection pipe and the second oil injection pipe, subtracting the oil production amount of the first oil production pipe and the second oil production pipe, and adding the oil amount in the oil sand in the step 2), namely the oil amount saturated into the shell;
4) closing the oil supply unit, opening the steam supply unit, injecting steam into the shell from the steam injection pipe, collecting temperature data in the shell by the temperature detection device, transmitting the temperature data to the control system, and processing the obtained temperature data by the control system to obtain the development process of the steam cavity; the collecting unit collects the crude oil discharged by the first oil production pipe and the second oil production pipe and the produced liquid discharged by the production pipes, and further calculates the accumulated oil production rate, the accumulated oil production and the recovery ratio;
5) when the production pipe does not discharge liquid any more, the experiment is ended, the steam supply unit and the constant temperature box are closed, the pressure in the shell is released to 0, and the shell is opened to observe the expansion rule of the steam cavity.
10. The method of claim 9, wherein: in the step 1), the mass ratio of the quartz sand to the epoxy resin glue is 0.16-0.12, and in the step 4), the set initial oil saturation is 85%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011299792.9A CN112324407A (en) | 2020-11-19 | 2020-11-19 | Method and device for researching steam cavity expansion boundary in SAGD development process |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011299792.9A CN112324407A (en) | 2020-11-19 | 2020-11-19 | Method and device for researching steam cavity expansion boundary in SAGD development process |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112324407A true CN112324407A (en) | 2021-02-05 |
Family
ID=74321516
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011299792.9A Pending CN112324407A (en) | 2020-11-19 | 2020-11-19 | Method and device for researching steam cavity expansion boundary in SAGD development process |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112324407A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113419035A (en) * | 2021-06-15 | 2021-09-21 | 中国石油大学(北京) | Experimental device and experimental method for developing heavy oil reservoir through multi-medium composite SAGD |
| CN113818853A (en) * | 2021-05-10 | 2021-12-21 | 中国石油大学(华东) | Experimental device for simulating steam injection of SAGD horizontal well and application method thereof |
Citations (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030173082A1 (en) * | 2001-10-24 | 2003-09-18 | Vinegar Harold J. | In situ thermal processing of a heavy oil diatomite formation |
| CA2642589A1 (en) * | 2006-02-17 | 2007-08-23 | Schlumberger Canada Limited | Method for formation permeability profile determination |
| CN202441353U (en) * | 2012-02-27 | 2012-09-19 | 东北石油大学 | Low pressure visualization two-dimensional sand-filling model used for heavy oil thermal recovery |
| CN103603658A (en) * | 2013-11-04 | 2014-02-26 | 中国石油大学(北京) | Oil production experimental device capable of simulating reservoir pressure supply |
| US20140251606A1 (en) * | 2012-04-12 | 2014-09-11 | Alexander Petrovich Linetskiy | Method For Increasing Hydrocarbon Extraction And For Ensuring The Continuous Operation Of Wells |
| CN104265255A (en) * | 2014-09-26 | 2015-01-07 | 中国石油天然气股份有限公司 | Two-dimensional microcosmic visual thickened oil replacement simulation experiment system and use method thereof |
| CN104405356A (en) * | 2014-11-24 | 2015-03-11 | 中国石油大学(北京) | Horizontal well steam drive two-dimensional physical simulation experimental device for thin bed heavy oil reservoir |
| CN104500013A (en) * | 2014-12-17 | 2015-04-08 | 中国石油大学(北京) | Multifunctional three-dimensional physical simulation experimental apparatus for thermal recovery by steam injection |
| CN104929600A (en) * | 2015-06-24 | 2015-09-23 | 中国石油大学(北京) | Oil sand SAGD visual two-dimensional physical simulation device and application method thereof |
| CN108590611A (en) * | 2018-04-26 | 2018-09-28 | 中国石油大学(华东) | Superheated steam injection, which recovers the oil, simulates the forming apparatus and experimental method of oil reservoir vapor chamber |
| CN109613214A (en) * | 2019-01-15 | 2019-04-12 | 中国地质大学（北京） | For studying interlayer to the experimental provision of SAGD mining effect |
| CN109723417A (en) * | 2019-01-07 | 2019-05-07 | 中国海洋石油集团有限公司 | A kind of recovery method turning fireflood suitable for oil-sand SAGD development late stage |
| CN110130871A (en) * | 2019-04-09 | 2019-08-16 | 中国石油大学(北京) | Channel bar type physical models of reservoir and preparation method thereof and experimental method |
| CN110761781A (en) * | 2019-11-12 | 2020-02-07 | 重庆大学 | Large-scale three-dimensional simulation method for exploiting super-heavy oil reservoir by FUSE technology |
| CN110847872A (en) * | 2019-11-25 | 2020-02-28 | 西南石油大学 | Experimental device for be used for studying intermediate layer to two horizontal well SAGD exploitation influences |
| 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 |
| CN111075441A (en) * | 2019-12-24 | 2020-04-28 | 中国石油化工股份有限公司 | Three-dimensional physical simulation experiment device and method for cold recovery after thermal recovery of side-bottom water heavy oil reservoir |
-
2020
- 2020-11-19 CN CN202011299792.9A patent/CN112324407A/en active Pending
Patent Citations (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030173082A1 (en) * | 2001-10-24 | 2003-09-18 | Vinegar Harold J. | In situ thermal processing of a heavy oil diatomite formation |
| CA2642589A1 (en) * | 2006-02-17 | 2007-08-23 | Schlumberger Canada Limited | Method for formation permeability profile determination |
| CN202441353U (en) * | 2012-02-27 | 2012-09-19 | 东北石油大学 | Low pressure visualization two-dimensional sand-filling model used for heavy oil thermal recovery |
| US20140251606A1 (en) * | 2012-04-12 | 2014-09-11 | Alexander Petrovich Linetskiy | Method For Increasing Hydrocarbon Extraction And For Ensuring The Continuous Operation Of Wells |
| CN103603658A (en) * | 2013-11-04 | 2014-02-26 | 中国石油大学(北京) | Oil production experimental device capable of simulating reservoir pressure supply |
| CN104265255A (en) * | 2014-09-26 | 2015-01-07 | 中国石油天然气股份有限公司 | Two-dimensional microcosmic visual thickened oil replacement simulation experiment system and use method thereof |
| CN104405356A (en) * | 2014-11-24 | 2015-03-11 | 中国石油大学(北京) | Horizontal well steam drive two-dimensional physical simulation experimental device for thin bed heavy oil reservoir |
| CN104500013A (en) * | 2014-12-17 | 2015-04-08 | 中国石油大学(北京) | Multifunctional three-dimensional physical simulation experimental apparatus for thermal recovery by steam injection |
| CN104929600A (en) * | 2015-06-24 | 2015-09-23 | 中国石油大学(北京) | Oil sand SAGD visual two-dimensional physical simulation device and application method thereof |
| CN108590611A (en) * | 2018-04-26 | 2018-09-28 | 中国石油大学(华东) | Superheated steam injection, which recovers the oil, simulates the forming apparatus and experimental method of oil reservoir vapor chamber |
| 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 |
| CN109723417A (en) * | 2019-01-07 | 2019-05-07 | 中国海洋石油集团有限公司 | A kind of recovery method turning fireflood suitable for oil-sand SAGD development late stage |
| CN109613214A (en) * | 2019-01-15 | 2019-04-12 | 中国地质大学（北京） | For studying interlayer to the experimental provision of SAGD mining effect |
| CN110130871A (en) * | 2019-04-09 | 2019-08-16 | 中国石油大学(北京) | Channel bar type physical models of reservoir and preparation method thereof and experimental method |
| CN110761781A (en) * | 2019-11-12 | 2020-02-07 | 重庆大学 | Large-scale three-dimensional simulation method for exploiting super-heavy oil reservoir by FUSE technology |
| CN110847872A (en) * | 2019-11-25 | 2020-02-28 | 西南石油大学 | Experimental device for be used for studying intermediate layer to two horizontal well SAGD exploitation influences |
| CN111075441A (en) * | 2019-12-24 | 2020-04-28 | 中国石油化工股份有限公司 | Three-dimensional physical simulation experiment device and method for cold recovery after thermal recovery of side-bottom water heavy oil reservoir |
Non-Patent Citations (7)
| Title |
|---|
| 代树红: "《基于数字图像相关方法的城市活断层破裂扩展研究》", 30 June 2019, 东北大学出版社 * |
| 张洪宝等: "超稠油油藏烟道气辅助SAGD物理模拟实验", 《断块油气田》 * |
| 曲同慈: "辽河盆地西部凹陷特超稠油油藏利用水平井方式提高采收率研究", 《中国博士学位论文全文数据库工程科技Ι辑》 * |
| 林伯韬等: "基于真三轴实验研究超稠油储集层压裂裂缝扩展规律", 《石油勘探与开发》 * |
| 王倩等: "超稠油Ⅲ类油藏夹层发育模式及SAGD提高采收率技术", 《特种油气藏》 * |
| 魏绍蕾等: "夹层对加拿大麦凯河油砂区块双水平井蒸汽辅助重力泄油开发的影响" * |
| 魏绍蕾等: "夹层对加拿大麦凯河油砂区块双水平井蒸汽辅助重力泄油开发的影响", 《油气地质与采收率》 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113818853A (en) * | 2021-05-10 | 2021-12-21 | 中国石油大学(华东) | Experimental device for simulating steam injection of SAGD horizontal well and application method thereof |
| CN113419035A (en) * | 2021-06-15 | 2021-09-21 | 中国石油大学(北京) | Experimental device and experimental method for developing heavy oil reservoir through multi-medium composite SAGD |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112324407A (en) | Method and device for researching steam cavity expansion boundary in SAGD development process | |
| CN107238627B (en) | Comprehensive experiment loop system for forced circulation of heat conduction oil working medium | |
| CN105544494B (en) | A kind of controllable temperature washes the method mended salt soil experimental rig and its test soil sample | |
| WO2022000833A1 (en) | Permafrost formation thawing and subsidence test simulation device and method | |
| CN105136991B (en) | Multifunctional crack flow guide capability test system and method | |
| CN102864793B (en) | Test device for simulating permafrost region well heat insulation or heating | |
| CN103375155B (en) | The linear physical simulation system of heavy crude reservoir thermal recovery | |
| CN103527176A (en) | Stereoscopic development three-dimensional experimental device of heavy oil reservoir | |
| CN105952424A (en) | Supercritical water-oil displacement simulator and method | |
| CN106593383B (en) | The hydraulic fracturing physical simulating method of underground rock core | |
| CN106645261A (en) | Large-sized multifunctional artificial freezing platform | |
| CN205840857U (en) | A kind of heavy crude heat extraction High Temperature High Pressure two-dimensional physical analogue experiment installation | |
| US11905812B2 (en) | Intra-layer reinforcement method, and consolidation and reconstruction simulation experiment system and evaluation method for gas hydrate formation | |
| CN108868716A (en) | One kind is for evaluating CO2System and method of the lotion to oil reservoir Flooding Efficiency | |
| CN108590611B (en) | Forming device and experimental method for injecting superheated steam to oil extraction simulation oil reservoir steam cavity | |
| CN105298488A (en) | Diversion capacity testing method under non-continuous filling mode | |
| CN110469301A (en) | One kind adopting simulator for heavy crude heat extraction three-dimensional note under large-scale model | |
| Pang et al. | An investigation into propagation behavior of the steam chamber during expanding-solvent SAGP (ES-SAGP) | |
| CN108956425A (en) | A kind of device and method measuring extra-viscous oil reservoir initial water permeability | |
| CN109556658A (en) | A kind of energy pile efficiency of pile groups experimental rig | |
| CN116856922A (en) | Experimental device and method for distribution form of dominant channels among steam flooding wells of heavy oil reservoirs | |
| CN108760575A (en) | Consider that hydrate decompression exploitation induces sand borehole wall static liquefaction model test apparatus | |
| CN109085169A (en) | The interior blistering of Artificial Seismic Wave compound vacuole foam layer and dynamic foam stabilizing integration device for evaluating performance and method under reservoir condition | |
| CN205557493U (en) | Salt soil test device is washed - mends to controllable temperature | |
| CN109669027A (en) | A kind of detection device and detection method of for transformer oil vacuum antifoam property |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20210205 |
|
| RJ01 | Rejection of invention patent application after publication |