SUPPORTED CATALYST-ASSISTED MICROWAVE METHOD FOR EXPLOITING HEAVY OIL RESERVOIR

Abstract

The invention relates to the recovery of heavy oil reservoirs, and more particularly to a supported catalyst-assisted microwave method for exploiting a heavy oil reservoir. The method includes: (1) injecting a slug of a supported catalyst fluid into the heavy oil reservoir; (2) placing a microwave generator in the heavy oil reservoir to perform volumetric heating on an oil layer containing the supported catalyst fluid; and (3) turning off the microwave generator and injecting water into the heavy oil reservoir for subsequent displacement, where a water injection rate is 3 m/d or less.

Claims

1. A supported catalyst-assisted microwave method for exploiting a heavy oil reservoir, comprising: (1) injecting a slug of a supported catalyst fluid into the heavy oil reservoir at 0.050.1 PV and an injection rate of less than or equal to 3 m/d; wherein the heavy oil reservoir has a single layer thickness of larger than or equal to 5 m, a net-gross thickness ratio of more than 0.5, a buried depth of 10003000 m, a reservoir porosity of 2030%, a permeability of more than 1 mD and a reservoir pore throat diameter of larger than 1 m; the heavy oil reservoir at a formation temperature has a degassed oil viscosity of less than or equal to 20,000 mPa.Math.s, an oil saturation of more than or equal to 40%, and a content of heavy components in heavy oil of 1040%; the supported catalyst fluid consists of 0.050.1% by weight of a supported catalyst, and water; and the supported catalyst is magnetic graphene oxide nanoparticle; (2) placing a microwave generator in the heavy oil reservoir to perform volumetric heating on an oil layer containing the supported catalyst fluid; and (3) turning off the microwave generator and injecting water into the heavy oil reservoir for subsequent displacement, wherein a water injection rate is 3 m/d or less.

2. The method of claim 1, wherein the magnetic graphene oxide nanoparticle is composed of graphene oxide and Fe.sub.3O.sub.4 nanoparticle loaded thereon.

3. The method of claim 2, wherein the Fe.sub.3O.sub.4 nanoparticle loaded on the magnetic graphene oxide nanoparticle is 2040% by weight of the magnetic graphene oxide nanoparticle.

4. The method of claim 2, wherein the graphene oxide has a particle size of 100 nm, and the Fe.sub.3O.sub.4 nanoparticle has a particle size of 20100 nm.

5. The method of claim 1, wherein in step (1), the injection rate of the slug of the supported catalyst fluid is 23 m/d.

6. The method of claim 1, wherein in step (3), the water injection rate is 2 m/d3 m/d.

7. The method of claim 1, wherein a volume ratio of the injected water to the supported catalyst fluid is 5:1 or more.

8. The method of claim 7, wherein the volume ratio of the injected water to the supported catalyst fluid is 510:1.

9. The method of claim 1, wherein in step (2), the microwave generator has a microwave frequency of 2450 MHz and a power of 700 W.

10. The method of claim 1, wherein in step (2), the volumetric heating is performed for 530 min.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIG. 1 schematically shows a micro displacement experiment and a micro glass model according to an embodiment of the invention.

[0030] FIG. 2 schematically shows the process of an experiment according to Example 4 of the invention.

[0031] FIG. 3 schematically shows the exploitation of a heavy oil reservoir using a supported catalyst assisted-microwave method according to an embodiment of the invention, where the supported catalyst is hydrophilic magnetic graphene oxide (MGO), which can be reduced to lipophilic magnetic graphene (MG) through the microwave radiation.

[0032] FIG. 4 shows the relationship between particle size of Fe.sub.3O.sub.4 nanoparticle and viscosity-reducing rate of the heavy oil under 50 C. according to Experimental example 1 of the invention.

[0033] FIG. 5 shows the relationship between loading amount of Fe.sub.3O.sub.4 nanoparticle and viscosity-reducing rate of the heavy oil under 50 C. according to Experimental example 2 of the invention.

[0034] FIG. 6 shows the relationship between microwave power and viscosity-reducing rate of the heavy oil under 50 C. according to Experimental example 3 of the invention.

[0035] FIG. 7 shows the relationship between microwave heating time and viscosity-reducing rate of the heavy oil under 50 C. according to Experimental example 4 of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

[0036] The invention will be described in detail with reference to the following embodiments.

Example 1

[0037] Individual experimental devices were checked and connected according to FIG. 1 to establish a micro model, which was washed with ethanol and ultrapure water before the experiment. The experiment was carried out as follows.

[0038] (1) The micro model was vacuumized.

[0039] (2) The micro model in a holder was preheated by a heating jacket for 2 h, and a confining pressure of the micro model was set to 1 MPa.

[0040] (3) The micro model was sequentially saturated with water and experimental heavy oil.

[0041] (4) The micro model was injected with a supported catalyst fluid at an injection rate of 2.5 m/d, and then irradiated with microwave for 5 min.

[0042] (5) The micro model was subjected to subsequent water drive at an injection rate of 2.5 m/d.

[0043] (6) During the experiment, a microscopic digital camera system was employed for real-time recording of the displacement process.

[0044] To simulate a heavy oil reservoir, the micro model was prepared to have a width of 5 cm, a length of 5 cm, a pore throat diameter of 50 m and an oil saturation of 95%. The experimental heavy oil had a viscosity of 80 mPa.Math.s at 50 C. and a heavy component (colloid, asphaltene) content of 12%. The supported catalyst was magnetic graphene oxide nanoparticle, which was composed of graphene oxide with a particle size of 100 nm and Fe.sub.3O.sub.4 nanoparticle with a particle size of 20 nm loaded thereon. The Fe.sub.3O.sub.4 nanoparticle was 30% by weight of the magnetic graphene oxide nanoparticle. The supported catalyst fluid consisted of 0.05% by weight of the supported catalyst and water. An injection amount of the supported catalyst fluid slug was 0.1 PV, and an injection amount of water in the subsequent water drive was 0.5 PV.

Example 2

[0045] Individual experimental devices were checked and connected according to FIG. 1 to establish a micro model, which was washed with ethanol and ultrapure water before the experiment. The experiment was carried out as follows.

[0046] (1) The micro model was vacuumized.

[0047] (2) The micro model in a holder was preheated by a heating jacket for 2 h, and a confining pressure of the micro model was set to 1 MPa.

[0048] (3) The micro model was sequentially saturated with water and experimental heavy oil.

[0049] (4) The micro model was injected with a supported catalyst fluid at an injection rate of 2.5 m/d, and then irradiated with microwave for 5 min.

[0050] (5) The micro model was subjected to subsequent water drive at an injection rate of 2.5 m/d.

[0051] (6) During the experiment, a microscopic digital camera system was employed for real-time recording of the displacement process.

[0052] To simulate a heavy oil reservoir, the micro model was prepared to have a width of 5 cm, a length of 5 cm, a pore throat diameter of 50 m and an oil saturation of 95%. The experimental heavy oil had a viscosity of 80 mPa.Math.s at 50 C. and a heavy component (colloid, asphaltene) content of 12%. The supported catalyst was magnetic graphene oxide nanoparticle, which was composed of graphene oxide with a particle size of 100 nm and Fe.sub.3O.sub.4 nanoparticle with a particle size of 20 nm loaded thereon. The Fe.sub.3O.sub.4 nanoparticle was 30% by weight of the magnetic graphene oxide nanoparticle. The supported catalyst fluid consisted of 0.05% by weight of the supported catalyst and water. An injection amount of the supported catalyst fluid slug was 0.1 PV, and an injection amount of water in the subsequent water drive was 1 PV.

Example 3

[0053] Individual experimental devices were checked and connected according to FIG. 1 to establish a micro model, which was washed with ethanol and ultrapure water before the experiment. The experiment was carried out as follows.

[0054] (1) The micro model was vacuumized.

[0055] (2) The micro model in a holder was preheated by a heating jacket for 2 h, and a confining pressure of the micro model was set to 1 MPa.

[0056] (3) The micro model was sequentially saturated with water and experimental heavy oil.

[0057] (4) The micro model was injected with a supported catalyst fluid at an injection rate of 2.5 m/d, and then irradiated with microwave for 5 min.

[0058] (5) The micro model was subjected to subsequent water drive at an injection rate of 2.5 m/d.

[0059] (6) During the experiment, a microscopic digital camera system was employed for real-time recording of the displacement process.

[0060] To simulate a heavy oil reservoir, the micro model was prepared to have a width of 5 cm, a length of 5 cm, a pore throat diameter of 50 m and an oil saturation of 95%. The experimental heavy oil had a viscosity of 80 mPa.Math.s at 50 C. and a heavy component (colloid, asphaltene) content of 12%. The supported catalyst was magnetic graphene oxide nanoparticle, which was composed of graphene oxide with a particle size of 100 nm and Fe.sub.3O.sub.4 nanoparticle with a particle size of 20 nm loaded thereon. The Fe.sub.3O.sub.4 nanoparticle was 30% by weight of the magnetic graphene oxide nanoparticle. The supported catalyst fluid consisted of 0.1% by weight of the supported catalyst and water. An injection amount of the supported catalyst fluid slug was 0.1 PV, and an injection amount of water in the subsequent water drive was 0.5 PV.

Example 4

[0061] Individual experimental devices were checked and connected according to FIG. 1 to establish a micro model, which was washed with ethanol and ultrapure water before the experiment. The experiment was carried out as follows.

[0062] (1) The micro model was vacuumized.

[0063] (2) The micro model in a holder was preheated by a heating jacket for 2 h, and a confining pressure of the micro model was set to 1 MPa.

[0064] (3) The micro model was sequentially saturated with water and experimental heavy oil.

[0065] (4) The micro model was injected with a supported catalyst fluid at an injection rate of 2.5 m/d, and then irradiated with microwave for 5 min.

[0066] (5) The micro model was subjected to subsequent water drive at an injection rate of 2.5 m/d.

[0067] (6) During the experiment, a microscopic digital camera system was employed for real-time recording of the displacement process.

[0068] To simulate a heavy oil reservoir, the micro model was prepared to have a width of 5 cm, a length of 5 cm, a pore throat diameter of 50 m and an oil saturation of 95%. The experimental heavy oil had a viscosity of 80 mPa.Math.s at 50 C. and a heavy component (colloid, asphaltene) content of 12%. The supported catalyst was magnetic graphene oxide nanoparticle, which was composed of graphene oxide with a particle size of 100 nm and Fe.sub.3O.sub.4 nanoparticle with a particle size of 20 nm loaded thereon. The Fe.sub.3O.sub.4 nanoparticle was 30% by weight of the magnetic graphene oxide nanoparticle. The supported catalyst fluid consisted of 0.1% by weight of the supported catalyst and water. An injection amount of the supported catalyst fluid slug was 0.5 PV, and an injection amount of water in the subsequent water drive was 1 PV.

[0069] It can be concluded from FIG. 2 that most of the remaining oil was still not extracted after the supported catalyst fluid drive. After the microwave heating treatment for 5 min, some oil and water re-transported, and the subsequent water drive provided sufficient power to extract most of the remaining viscosity-reduced oil.

Comparative Example 1

[0070] Individual experimental devices were checked and connected according to FIG. 1 to establish a micro model. The model was washed with ethanol and ultrapure water before the experiment began. The experiment was carried out as follows.

[0071] (1) The micro model was vacuumized.

[0072] (2) The micro model in a holder was preheated by a heating jacket for 2 h, and a confining pressure of the micro model was set to 1 MPa.

[0073] (3) The micro model was sequentially saturated with water and experimental heavy oil.

[0074] (4) The micro model was subjected to subsequent water drive at an injection rate of 2.5 m/d.

[0075] (5) During the experiment, a microscopic digital camera system was employed for real-time recording of the displacement process.

[0076] To simulate a heavy oil reservoir, the model was prepared to have a width of 5 cm, a length of 5 cm, a pore throat diameter of 50 m and an oil saturation of 95%. The experimental heavy oil had a viscosity of 80 mPa.Math.s at 50 C. and a heavy component (colloid, asphaltene) content of 12%. An injection amount of water in the subsequent water drive was 0.5 PV.

Comparative Example 2

[0077] Experimental devices were checked and connected to establish a model according to FIG. 1. The model was washed with ethanol and ultrapure water before the experiment began. The experiment was carried out as follows.

[0078] (1) The micro model was vacuumized.

[0079] (2) The micro model in a holder was preheated by a heating jacket for 2 h, and a confining pressure of the micro model was set to 1 MPa.

[0080] (3) The micro model was sequentially saturated with water and experimental heavy oil.

[0081] (4) The micro model was subjected to subsequent water drive at an injection rate of 2.5 m/d.

[0082] (5) During the experiment, a microscopic digital camera system was employed for real-time recording of the displacement process.

[0083] To simulate a heavy oil reservoir, the model was prepared to have a width of 5 cm, a length of 5 cm, a pore throat diameter of 50 m and an oil saturation of 95%. The experimental heavy oil had a viscosity of 80 mPa.Math.s at 50 C. and a heavy component (colloid, asphaltene) content of 12%. An injection amount of water in the subsequent water drive was 1 PV.

Comparative Example 3

[0084] Experimental devices were checked and connected to establish a model according to FIG. 1. The model was washed with ethanol and ultrapure water before the experiment began. The experiment was carried out as follows.

[0085] (1) The micro model was vacuumized.

[0086] (2) The micro model in a holder was preheated by a heating jacket for 2 h, and a confining pressure of the micro model was set to 1 MPa.

[0087] (3) The micro model was sequentially saturated with water and experimental heavy oil.

[0088] (4) The micro model was injected with a supported catalyst fluid at an injection rate of 2.5 m/d, and then irradiated with microwave for 5 min.

[0089] (5) The micro model was subjected to subsequent water drive at an injection rate of 2.5 m/d.

[0090] (6) During the experiment, a microscopic digital camera system was employed for real-time recording of the displacement process.

[0091] To simulate a heavy oil reservoir, the micro model was prepared to have a width of 5 cm, a length of 5 cm, a pore throat diameter of 50 m and an oil saturation of 95%. The experimental heavy oil had a viscosity of 80 mPa.Math.s at 50 C. and a heavy component (colloid, asphaltene) content of 12%. The supported catalyst was magnetic graphene oxide nanoparticle, which was composed of graphene oxide with a particle size of 100 nm and Fe.sub.3O.sub.4 nanoparticle with a particle size of 20 nm loaded thereon. The Fe.sub.3O.sub.4 nanoparticle was 30% by weight of the magnetic graphene oxide nanoparticle. The supported catalyst fluid consisted of 0.05% by weight of the supported catalyst and water. An injection amount of the supported catalyst fluid slug was 0.1 PV, and an injection amount of water in the subsequent water drive was 0.5 PV.

TABLE-US-00001 TABLE 1 Parameters and recovery ratios of Examples 1-4 and Comparative Examples 1-3 Injection amount Mass fraction Injection amount of water for the of the supported of the supported Microwave subsequent water Recovery No. catalyst, % catalyst fluid, PV treatment drive, PV ratio, % Example 1 0.05 0.1 Yes 0.5 66.5 Example 2 0.05 0.1 Yes 1 69.4 Example 3 0.1 0.1 Yes 0.5 79.4 Example 4 0.1 0.5 Yes 1 87.6 Comparative No 0.5 41.5 Example 1 Comparative No 1 50.8 Example 2 Comparative 0.05 0.1 No 0.5 45.5 Example 3

[0092] The recovery ratios obtained in Examples 1-4 and Comparative Examples 1-3 were shown in Table 1. It can be concluded from Table 1 that in the case of the same injection parameters, the introduction of microwave treatment can lead to an increase of 21% in the recovery ratio; the injection of 0.1 PV of the supported catalyst fluid (containing 0.05% by weight of the supported catalyst) boosted the recovery ratio by 4%; and the combined use of the supported catalyst fluid and the microwave treatment increased the recovery ratio by at least 25% compared to the single use of the subsequent water drive. In addition, the recovery ratio was positively correlated with the injection amount of the supported catalyst fluid and the mass fraction of the supported catalyst.

Experimental Example 1

[0093] A heavy oil, having a viscosity of 83,400 mPa.Math.s at 50 C., was added with 2 wt % of hydrogen donor and divided into seven parts which were exactly the same and respectively numbered. The seven parts of the heavy oil were treated as follows. Part 1 was free of any additives; Part 2 was added with 1 wt % of Fe.sub.3O.sub.4 nanoparticle with a particle size of 5.5 nm; Part 3 was added with 1 wt % of Fe.sub.3O.sub.4 nanoparticle with a particle size of 20 nm; Part 4 was added with 1 wt % of Fe.sub.3O.sub.4 nanoparticle with a particle size of 50 nm; Part 5 was added with 1 wt % of Fe.sub.3O.sub.4 nanoparticle with a particle size of 100 nm; Part 6 was added with 1 wt % of Fe.sub.3O.sub.4 nanoparticle with a particle size of 1000 nm; and Part 7 was added with 1 wt % of Fe.sub.3O.sub.4 nanoparticle with a particle size of 10,000 nm. The seven parts of the heavy oil were heated under the microwave irradiation at a frequency of 2450 MHz and a power of 700 W for 30 min. After cooled to room temperature, the seven parts of the heavy oil were measured for viscosity, and the viscosity at 50 C. was used as the initial viscosity in the calculation of a viscosity-reducing rate, where the viscosity-reducing rate referred to a percentage of the heavy oil viscosity reduced after the catalyst was added. Viscosity-reducing rates of heavy oil at 50 C. corresponding to Fe.sub.3O.sub.4 nanoparticles of different particle sizes were shown in Table 2.

TABLE-US-00002 TABLE 2 Viscosity-reducing rates at 50 C. corresponding to Fe.sub.3O.sub.4 nanoparticles of different particle sizes No. 1 2 3 4 5 6 7 Particle size of 5.5 20 50 100 1000 10,000 Fe.sub.3O.sub.4 nanoparticle(nm) Viscosity(mPa .Math. s) 70,200 56,600 41,400 40,000 40,200 50,200 57,900 Viscosity-reducing 15.83 32.13 50.36 52.04 51.80 39.81 30.58 rate(%)

[0094] It can be seen from Table 2 and FIG. 4 that Parts 3, 4 and 5 which were respectively added with Fe.sub.3O.sub.4 nanoparticle having a particle size of 20 nm-100 nm all had a viscosity-reducing rate of 50% or more, while Parts 6 and 7 respectively added with a Fe.sub.3O.sub.4 micro-particle only had a viscosity-reducing rate of 30%-40%. Therefore, nano catalysts worked better within a certain range. Specifically, in the range, due to a larger surface area, better dispersion in the heavy oil, higher conversion efficiency for microwaves and certain volume effect, the nano catalysts were greatly enhanced in the magnetic property and catalytic activity, significantly promoting the catalytic efficiency. Moreover, the experimental results also proved that undersized Fe.sub.3O.sub.4 nanoparticle, such as Part 1, had a general viscosity-reducing effect, which was mainly because that the undersized particles were prone to serious agglomeration to form a larger particle, losing the unique physicochemical property. Given the above, the Fe.sub.3O.sub.4 nanoparticle preferably had a particle size of 20-100 nm.

Experimental Example 2

[0095] A heavy oil, having a viscosity of 92,000 mPa.Math.s at 50 C., was added with 2 wt % of hydrogen donor and divided into six parts which were exactly the same and respectively numbered. The six parts of the heavy oil were treated as follows. Part 1 was added with 1 wt % magnetic graphene oxide with a loading amount of 0%; Part 2 was added with 1 wt % magnetic graphene oxide with a loading amount of 10%; Part 3 was added with 1 wt % magnetic graphene oxide with a loading amount of 20%; Part 4 was added with 1 wt % magnetic graphene oxide with a loading amount of 30%; Part 5 was added with 1 wt % magnetic graphene oxide with a loading amount of 40%; Part 6 was added with 1 wt % magnetic graphene oxide with a loading amount of 50%. The six parts of the heavy oil were heated under the microwave irradiation at a frequency of 2450 MHz and a power of 700 W for 30 min. After cooled to room temperature, the six parts of the heavy oil were measured for viscosity, and the viscosity at 50 C. was used as the initial viscosity in the calculation of a viscosity-reducing rate, where the viscosity-reducing rate referred to a percentage of the heavy oil viscosity reduced after the catalyst was added. The supported Fe.sub.3O.sub.4 nanoparticle had a same particle size of 20 nm. Viscosity-reducing rates of heavy oil at 50 C. corresponding to different loading amounts of Fe.sub.3O.sub.4 nanoparticle were shown in Table 3.

TABLE-US-00003 TABLE 3 Viscosity-reducing rates at 50 C. corresponding to different loading amounts of Fe.sub.3O.sub.4 nanoparticle No. 1 2 3 4 5 6 Loading amount % 0 10 20 30 40 50 Viscosity(mPa .Math. s) 75,900 59,600 55,000 50,100 47,300 45,200 Viscosity-reducing 17.5 35.22 40.22 45.54 48.59 50.87 rate(%)

[0096] It can be seen from Table 3 and FIG. 5 that the viscosity-reducing rate was gradually increased with the increase in the loading amount of the Fe.sub.3O.sub.4 nanoparticle, but the increasing speed was gradually reduced, which was because that an excessive loading amount will result in the agglomeration of the supported catalyst, reducing the dispersibility in water. Therefore, a loading amount of the Fe.sub.3O.sub.4 nanoparticle was preferably 20%-40%.

Experimental Example 3

[0097] A heavy oil, having a viscosity of 88,600 mPa.Math.s at 50 C., was added with 2 wt % of hydrogen donor and 1 wt % magnetic graphene oxide, and divided into four parts which were exactly the same and respectively numbered. The four parts of the heavy oil were treated as follows. The four parts of the heavy oil were heated under the microwave irradiation at a frequency of 2450 MHz and different powers of 385 W, 539 W, 700 W and 850 W for 30 min. After cooled to room temperature, the four parts of the heavy oil were measured for viscosity, and the viscosity at 50 C. was used as the initial viscosity in the calculation of a viscosity-reducing rate, where the viscosity-reducing rate referred to a percentage of the heavy oil viscosity reduced after the catalyst was added. Viscosity-reducing rates of heavy oil at 50 C. corresponding to different microwave powers were shown in Table 4.

TABLE-US-00004 TABLE 4 Viscosity-reducing rates at 50 C. corresponding to different microwave powers No. 1 2 3 4 Microwave power(W) 385 539 700 850 Viscosity(mPa .Math. s) 64,800 53,600 50,200 48,400 Viscosity-reducing 26.86 39.50 43.34 45.37 rate(%)

[0098] It can be seen from Table 4 and FIG. 6 that the viscosity-reducing rate was gradually increased as the microwave power increased, but the increasing speed was gradually reduced. However, excessive microwave power will bring a series of safety problems and loss in the economic benefits.

Experimental Example 4

[0099] A heavy oil, having a viscosity of 88,600 mPa.Math.s at 50 C., was added with 2 wt % of hydrogen donor and 1 wt % magnetic graphene oxide, and divided into four parts which were exactly the same and respectively numbered. The four parts of the heavy oil were treated as follows. The four parts of the heavy oil were heated under the microwave irradiation at a frequency of 2450 MHz and a power of 700 W for 5 min, 10 min, 20 min and 30 min, respectively. After cooled to room temperature, the four parts of the heavy oil were measured for viscosity, and the viscosity at 50 C. was used as the initial viscosity in the calculation of a viscosity-reducing rate, where the viscosity-reducing rate referred to a percentage of the heavy oil viscosity reduced after the catalyst was added. Viscosity-reducing rates of heavy oil at 50 C. corresponding to different microwave heating times were shown in Table 5.

TABLE-US-00005 TABLE 5 Viscosity-reducing rates at 50 C. corresponding to different microwave heating times No. 1 2 3 4 Microwave heating 5 10 20 30 time(min) Viscosity(mPa .Math. s) 70,300 52,600 50,200 50,600 Viscosity-reducing 20.65 40.63 43.34 42.89 rate(%)

[0100] It can be seen from Table 5 and FIG. 7 that with the extension of the microwave heating time, the viscosity-reducing rate was gradually increased, but the growth was gradually slowed down. Moreover, excessive microwave heating may give rise to a series of safety problems and loss in the economic benefits.