Sandstone geothermal well plug removal device and method based on gas-liquid mixture

Abstract

The application discloses a device and method for unblocking sandstone geothermal well based on gas-liquid mixture, and relates to the technical field of geothermal water recycling.The device comprises a geothermal recharge well, a pump vehicle, an air compressor, a water tank, a filter tank, a sand remover, a water collecting pipeline, a valve and a pipeline.The pipeline comprises an input pipeline and an output pipeline.The one end of the pump vehicle and the air compressor are connected with the geothermal recharge well through the input pipeline.The other end of the geothermal recharge well is connected with the sand remover through the output pipeline.The other end of the sand remover is connected with the filter tank through the pipeline.The other end of the filter tank is connected with the first end of the water tank through the pipeline.The second end of the water tank is connected with the other end of the pump vehicle through the pipeline.The third end of the water tank is connected with the water collecting pipeline through the valve.The application has the advantages of obvious improvement of unblocking effect of the sandstone geothermal recharge well, shortened operation period, saved operation cost, environmental protection effect, and prolonged service life of the sandstone geothermal recharge well.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of geothermal water recycling, and particularly relates to a device and method for unblocking a sandstone geothermal well based on a gas-liquid mixture. BACKGROUND

[0002] Geothermal energy is a clean and renewable energy without pollution, and sandstone geothermal energy accounts for a major part of geothermal energy. To solve the sustainable utilization of sandstone geothermal resources and avoid environmental pollution, the most effective way is to reinject geothermal tail water. However, the biggest problem of reinjection is the plugging of the near-well thermal reservoir. Temporary unblocking can temporarily alleviate the plugging of the reservoir, but must be completely unblocked periodically. At present, there are periodic unblocking technologies such as gas lifting, pulling piston, acidification, and fracturing. The commonly used gas lifting unblocking technology refers to lowering a gas lifting string into the well to a depth of about 700 m, using a gas compressor to send compressed gas into the well through the gas lifting string, forming a negative pressure above 700 m in the well, inducing hot water out of the well, and achieving the purpose of cleaning and reinjecting the plugged well. Since the gas lifting string is lowered to a relatively shallow depth, the cleaning effect of this technology is limited, and the reinjection amount of the geothermal well after unblocking decreases rapidly, resulting in a shortened service life of the reinjection well. The unblocking technologies such as pulling piston, acidification, and fracturing have the characteristics of inconvenient field operation, long working hours, and high cost, which are not conducive to large-scale promotion to unblock geothermal reinjection wells. SUMMARY

[0003] To solve the problem of dirty plugging of geothermal reinjection wells, the application provides a device for unblocking a sandstone geothermal well based on a gas-liquid mixture, which comprises a geothermal reinjection well, a pump truck, an air compressor, a water tank, a filter tank, a sand remover, a water collection pipeline, a valve, a pipeline, an input pipeline, and an output pipeline. The water tank comprises a water tank first end, a water tank second end, and a water tank third end. The geothermal reinjection well is connected to the pump truck and the air compressor through the input pipeline respectively. The geothermal reinjection well is connected to the sand remover through the output pipeline. The sand remover is connected to the filter tank through the pipeline. The filter tank is connected to the water tank first end through the pipeline. The water tank second end is connected to the pump truck through the pipeline. The water tank third end is connected to the water collection pipeline through the valve.

[0004] Further, the input pipeline is connected to the thermal reservoir well section.

[0005] Further, the geothermal reinjection well comprises a sealed wellhead for separating geothermal water and air, so as to seal the wellhead of the geothermal reinjection well.

[0006] Further, the geothermal reinjection well further comprises a pump chamber sleeve, a cementing well, and a production sleeve. The pump chamber sleeve is fixed by the cementing well. The pump chamber sleeve is connected to the production sleeve.

[0007] Further, the geothermal recharging well further comprises a filter pipe, the pump chamber sleeve is connected with the filter pipe through the production casing pipe to establish a firm channel to protect the well wall, and the filter pipe is arranged in the geothermal reservoir well section.

[0008] Further, the geothermal recharging well further comprises a filter pipe, the pump chamber sleeve is connected with the filter pipe through the production casing pipe to establish a firm channel to protect the well wall, and the filter pipe is arranged in the geothermal reservoir well section.

[0009] A method for unblocking a sandstone geothermal well based on a gas-liquid mixture, steps are as follows:

[0010] S1, according to the measured data of the geothermal exploitation recharging process, the well completion data, the regional geothermal reservoir material characteristics, and the reservoir mineral composition, the reasons and the degree of the geothermal recharging well blockage are analyzed, and the type, concentration, soaking time and well flushing construction scheme of the used well flushing fluid are designed;

[0011] S2, the original recharging process device is removed, the geothermal well unblocking device is connected, and the well flushing process is carried out;

[0012] S3, the well flushing fluid is prepared in advance, and 2-3 inches of the input pipe is lowered to the geothermal reservoir well section area according to the depth of the geothermal recharging well;

[0013] S4, the well flushing fluid prepared in advance is injected into the geothermal reservoir well section by the input pipe, and after soaking for 8-16 hours according to the degree of the geothermal recharging well blockage, the gas-liquid mixture is prepared for flushing;

[0014] S5, the pump truck is started to pump water from the water tank, the water is injected into the geothermal recharging well through the input pipe, the air compressor is started after the pump pressure is stabilized, the gas valve is opened, the gas is gradually supplied, the gas-liquid mixture is formed, and the gas-liquid mixture is injected into the geothermal reservoir well section area to clean and unblock, the gas-liquid mixture returns along the annulus between the input pipe and the inner wall of the geothermal recharging well, the blocked material washed out enters the desander through the output pipe for desanding, and then the clean water is filtered through the filter tank to form clean water, the clean water is stored in the water tank, and the well flushing cycle is established; the circulating water containing the medicine is transported to the designated place by the tank truck, and is subjected to harmless treatment; with the increase of the well flushing time, the geothermal reservoir well section is gradually unblocked, the water yield of the formation is increased, the excess water returns to the water collecting pipe line, and the continuous well flushing is carried out, the cleaning time is 8-16 hours, and the geothermal recharging well is unblocked until the geothermal recharging well is unblocked.

[0015] S6, the original recharging process device of the geothermal recharging well is restored.

[0016] The beneficial effects of the present application are:

[0017] (1) Improve the unblocking effect: The commonly used gas lift unblocking technology can only restore the geothermal reinjection volume of the well to about 84% of the original initial reinjection volume. By using the gas-water mixed unblocking technology, the reinjection volume of the well can be restored to about 96% of the original initial reinjection volume, which greatly improves the unblocking effect.

[0018] (2) Cost savings: Unblocking techniques such as piston pulling, acidizing, and fracturing are inconvenient to operate on-site and require high operating costs. In contrast, the gas-water mixing unblocking process only requires one trip to run the tubing, uses the same chemicals as those used for conventional water well washing, and the air compressor is used for approximately 8-16 hours, resulting in relatively lower total operating costs.

[0019] (3) Short construction period: For a single reinjection well, gas lift unblocking generally takes 3-5 days, and piston unblocking generally takes 4-7 days; while gas-water mixed unblocking technology takes 1-2 days, shortening the construction period.

[0020] (4) It has environmental protection effect: At present, most of the water coming out of the well is discharged without being recycled to the water collection pipeline due to the air lift or piston unblocking technology, which wastes geothermal water resources and is not environmentally friendly; while the air-water mixed unblocking technology filters and purifies the water through a sand remover and filter tank, and then circulates the well to wash it, so that all the water eventually returns to the water collection pipeline.

[0021] In summary, the technology of this invention significantly improves the unblocking effect of sandstone geothermal reinjection wells, shortens the operation period, saves operating costs, and has environmental benefits. It can significantly delay the decline in reinjection volume in sandstone geothermal reinjection wells, thereby extending their service life. This provides positive technical support for large-scale geothermal development and utilization. With the increasing national emphasis on geothermal energy, the number and scale of geothermal development projects are growing, and each project has a large number of geothermal reinjection wells that require regular and timely unblocking. The technology of this invention can meet these practical needs. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the surface process of the sandstone geothermal well gas-water mixing unblocking technology of the present invention;

[0023] Figure 2 This is a schematic diagram of the downhole process of the gas-water mixing unblocking technology for sandstone geothermal wells according to the present invention.

[0024] The diagram is marked as follows:

[0025] 1, geothermal recharging well, 1-1, hot reservoir well section, 1-2, sealed wellhead, 1-3, pump chamber casing, 1-4, cementing, 1-5 production casing, 1-6, water filter pipe, 1-7, sand pipe, 2, pump truck, 3, air compressor, 4, water tank, 41, first end of water tank, 42, second end of water tank, 43, third end of water tank, 5, filter tank, 6, sand remover, 7, water collection pipeline, 8, valve, 9, pipeline, 9-1, input pipeline, 9-2, output pipeline. DETAILED DESCRIPTION

[0026] Example 1

[0027] A sandstone geothermal well unblocking device based on gas-liquid mixture, comprising a geothermal recharging well 1, a pump truck 2, an air compressor 3, a water tank 4, a filter tank 5, a sand remover 6, a water collection pipeline 7, a valve 8 and a pipeline 9, the pipeline 9 comprising an input pipeline 9-1 and an output pipeline 9-2, the water tank 4 comprising a first end of water tank 41, a second end of water tank 42 and a third end of water tank 43, one end of the pump truck 2 and the air compressor 3 are connected with the geothermal recharging well 1 through the input pipeline 9-1, the other end of the geothermal recharging well 1 is connected with one end of the sand remover 6 through the output pipeline 9-2, the other end of the sand remover 6 is connected with one end of the filter tank 5 through the pipeline 9, the other end of the filter tank 5 is connected with the first end of water tank 41 through the pipeline 9, the second end of water tank 42 is connected with the other end of the pump truck 2 through the pipeline 9, and the third end of water tank 43 is connected with the water collection pipeline 7 through the valve 8.

[0028] The input pipeline 9-1 is connected to the hot reservoir well section 1-1.

[0029] The geothermal recharging well 1 comprises a sealed wellhead 1-2, which ensures that geothermal water is separated from air and realizes the sealing of the wellhead of the geothermal recharging well 1.

[0030] The geothermal recharging well 1 further comprises a pump chamber casing 1-3, cementing 1-4 and a production casing 1-5, the pump chamber casing 1-3 is fixed through the cementing 1-4, and the pump chamber casing 1-3 is connected with the production casing 1-5.

[0031] The geothermal recharging well 1 further comprises a water filter pipe 1-6, the pump chamber casing 1-3 is connected with the water filter pipe 1-6 through the production casing 1-5 to establish a firm channel and play a role in protecting the well wall, and the water filter pipe 1-6 is arranged in the hot reservoir well section 1-1.

[0032] The geothermal recharging well 1 further comprises a sand pipe 1-7, which is arranged in the hot reservoir well section 1-1 to play a role in sand setting.

[0033] A method for realizing sandstone geothermal well unblocking based on gas-liquid mixture, comprising the following steps:

[0034] S1, according to the measured data of geothermal exploitation and reinjection process, completion data, regional geothermal reservoir material characteristics, reservoir mineral composition, analyze the reasons and degree of geothermal reinjection well 1 blockage, design the type, concentration, soaking time and washing construction scheme of washing fluid used;

[0035] S2, remove the original reinjection process of geothermal reinjection well 1, connect the geothermal well unblocking device, and carry out the washing process;

[0036] S3, prepare the washing fluid in advance, and according to the depth of geothermal reinjection well 1, put 2-3 inch input pipeline 9-1 into the hot reservoir well section 1-1 area;

[0037] S4, inject the washing fluid prepared in advance into the downhole hot reservoir well section 1-1 through the input pipeline 9-1, and according to the degree of geothermal reinjection well 1 blockage, soak for 8-16 hours, and then prepare the gas-liquid mixture for flushing;

[0038] S5, start the pump truck 2 to pump water from the water tank 4, inject water into the geothermal reinjection well 1 through the input pipeline 9-1, start the air compressor 3 after the pump pressure is stable, open the air valve, gradually supply air, form a gas-liquid mixture, and inject it into the hot reservoir well section 1-1 area through the input pipeline 9-1 to clean and unblock, the gas-liquid mixture returns along the annulus between the input pipeline 9-1 and the inner wall of the geothermal reinjection well 1, the blocked material washed out enters the sand remover 6 for sand removal, and then passes through the filter tank 5 to form clean water, the clean water is stored in the water tank 4, and a washing cycle is established; the circulating water containing medicine is transported to the designated place by tank car, and harmless treatment is carried out, with the increase of washing time, the hot reservoir well section 1-1 is gradually unblocked, the formation water yield increases, and the excess water returns to the water collecting pipeline 7, the continuous cycle washing is carried out, the cleaning time is 8-16 hours, and the geothermal reinjection well 1 is unblocked until the geothermal reinjection well 1 is unblocked;

[0039] S6, restore the original reinjection process of geothermal reinjection well 1.

[0040] The present application makes the near-wellbore zone of the heat reservoir blocked by conventional water well washing chemicals such as sodium pyrophosphate and fire alkali to be cleaned, forms a higher negative pressure in the wellbore by inputting the pipeline 9-1 to the deep heat reservoir bottom section, and continuously flushes the heat reservoir by using the high-speed fluid formed by the gas-water mixture under the condition of continuous negative pressure, carries out the fine sand, clay mineral components and the like blocked in the heat reservoir pores with the reservoir water, dredges the heat reservoir water passage, and then uses the ground sand remover and filter tank to recycle the flushing liquid, and finally returns the flushing liquid to the water collecting pipeline. The sandstone heat reservoir recharging is a world-class problem, and the plugging removal technology is a bottleneck technology for large-scale development and utilization of geothermal energy. The process technical flow of the present application can obviously improve the plugging removal effect of the sandstone geothermal recharging well, is easy to operate, economical, applicable and environmentally friendly, and prolongs the service life of the sandstone geothermal recharging well, and provides positive technical support for large-scale development and utilization of geothermal energy.

[0041] Example 2

[0042] The process technical flow of the present application is used for plugging removal test in the Liaohua oilfield Huan 3 combined Paleogene Shahejie Formation sandstone geothermal well, Xing 1 mine Paleogene Dongying Formation sandstone geothermal well and Runchengyuan Neogene Guantao Formation sandstone geothermal well.

[0043] Jinshui 1-01 and Jinshui 1-02 wells were completed in 2008, the completion drilling depths were 2418m and 2410m respectively, the completion production was about 50m 3 / h, and the wellhead water temperature was 83℃. After short-term use, the wells were stopped, and after two years, the wells were put into use again, and it was found that the water yield was too small, and finally the plugging was removed by gas lifting for 5 days, and the effect was not obvious, and the wells could not be used. In 2014, the two geothermal wells were used again, and the plugging removal was carried out by pulling the piston for 7 days, and the effect was still not obvious, and the wells could not be used. In April 2019, the process technology of the present application was used for plugging removal operation of the two geothermal wells, first, the screen pipe well section was soaked for 8 hours, the screen pipe part was washed by gas-water mixture, and the well was washed for 24 hours, and the two geothermal wells were restored to the original water yield and water temperature at the completion time.

[0044] Yellow 6-5C well is a scrapped oil well, which was transformed into a geothermal well in 2016, the well depth is 2600m, the water production layer is Paleogene Dongying Formation sandstone heat reservoir, and after transformation, it is used as a geothermal recharging well to provide heating for the office building in the mining area. During the heating period, the plugging is removed by backwashing, and during the non-heating period, the plugging is removed by gas lifting, and the recharging amount shows a decreasing trend. In May 2019, the process technology of the present application was used, first, the perforated well section of the well was soaked for 8 hours, then the well was washed by gas-water mixture, and the well was washed for 16 hours, and after washing, the recharging amount basically recovered to the recharging amount when the well was transformed.

[0045] Xing 4, Xing 5, Xing 8 well is a water supply well completed in 1974, the exploitation layer is Neogene Guantao Formation groundwater, the well depth is about 1200 meters, after 2015, it is changed into Runchengyuan geothermal tail water recharge well, which is used for heating in the community, it is not lifted during heating period, and it is washed by gas lift method during non-heating period, the recharge capacity is basically restored, but the recharge water level has rising trend every year. In March 2020, the three geothermal recharge wells are respectively deblocked by using the process technology, and the recharge water level does not rise after deblocking.

[0046] Therefore, by using the sandstone geothermal well gas-water mixed deblocking process technology and the matching equipment, the deblocking effect of the geothermal recharge well is obviously improved, the present situation that the recharge capacity gradually decays is relieved, the well washing working hours are shortened, the operation cost is saved, and the service life of the geothermal recharge well is improved.

[0047] The above is only the preferred specific implementation mode of the present application, but the protection scope of the present application is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical scheme and concept of the present application within the technical range disclosed by the present application, which should be covered in the protection scope of the present application.

Claims

1. A method for realizing sandstone geothermal well plugging based on gas-liquid mixture, characterized in that, The device for unblocking sandstone geothermal well comprises a geothermal recharge well (1), a pump truck (2), an air compressor (3), a water tank (4), a filter tank (5), a sand remover (6), a water collecting pipeline (7), a valve (8), a pipeline (9), an input pipeline (9-1) and an output pipeline (9-2), the water tank (4) comprises a water tank first end (41), a water tank second end (42) and a water tank third end (43), the geothermal recharge well (1) is connected with the pump truck (2) and the air compressor (3) through the input pipeline (9-1) respectively, the geothermal recharge well (1) is connected with the sand remover (6) through the output pipeline (9-2), the sand remover (6) is connected with the filter tank (5) through the pipeline (9), the filter tank (5) is connected with the water tank first end (41) through the pipeline (9), the water tank second end (42) is connected with the pump truck (2) through the pipeline (9), and the water tank third end (43) is connected with the water collecting pipeline (7) through the valve (8). The input pipeline (9-1) is connected with a hot reservoir well section (1-1). The method for unblocking the sandstone geothermal well based on the gas-liquid mixture comprises the following steps: S1, according to the measured data of the geothermal exploitation recharge process, the well completion data, the regional geothermal reservoir material characteristics and the reservoir mineral composition, the reasons and the degree of the geothermal recharge well (1) blockage are analyzed, and the type, concentration, soaking time and washing construction scheme of the washing fluid used are designed; S2, the original recharge process device is removed, the geothermal well unblocking device is connected, and the washing process is carried out; S3, the washing fluid is prepared in advance, and the 2-3 inch input pipeline (9-1) is lowered to the hot reservoir well section (1-1) area according to the depth of the geothermal recharge well (1); S4, the washing fluid prepared in advance is injected into the downhole hot reservoir well section (1-1) through the input pipeline (9-1), and after soaking for 8-16 hours according to the degree of the geothermal recharge well (1) blockage, the gas-liquid mixture is prepared for flushing; S5, the pump truck (2) is started to pump water from the water tank (4), the water is injected into the geothermal recharge well (1) through the input pipeline (9-1), the air compressor (3) is started after the pump pressure is stable, the air valve is opened, the gas is gradually supplied, the gas-liquid mixture is formed, and the gas-liquid mixture is injected into the hot reservoir well section (1-1) area for cleaning and unblocking, the gas-liquid mixture returns along the annulus between the input pipeline (9-1) and the inner wall of the geothermal recharge well (1), the blocked materials flushed out enter the sand remover (6) through the output pipeline (9-2) for sand removal, and then the clean water is filtered through the filter tank (5) to form clean water, the clean water is stored in the water tank (4), and the washing circulation is established; the circulating water containing the medicine is transported to the designated place by the tank truck, and harmless treatment is carried out, with the increase of the washing time, the hot reservoir well section (1-1) is gradually unblocked, the water yield of the formation is increased, the excess water returns to the water collecting pipeline (7), the continuous circulation washing is carried out, the cleaning time is 8-16 hours, and the geothermal recharge well (1) is unblocked until the geothermal recharge well (1) is unblocked; S6, the original recharge process device of the geothermal recharge well (1) is restored.

2. The method for realizing sandstone geothermal well plugging removal based on gas-liquid mixture according to claim 1, characterized in that, The geothermal recharge well (1) comprises a sealed wellhead (1-2) for separating geothermal water from air, and the sealing of the wellhead of the geothermal recharge well (1) is realized.

3. The method for realizing sandstone geothermal well plugging removal based on gas-liquid mixture according to claim 1, characterized in that, The geothermal recharge well (1) further comprises a pump chamber casing (1-3), a cementing (1-4) and a production casing (1-5), the pump chamber casing (1-3) is fixed by the cementing (1-4), and the pump chamber casing (1-3) is connected with the production casing (1-5).

4. The method for realizing sandstone geothermal well plugging removal based on gas-liquid mixture according to claim 3, characterized in that, The geothermal recharge well (1) further comprises a water filter pipe (1-6), the pump chamber casing (1-3) is connected with the water filter pipe (1-6) through the production casing (1-5) to establish a firm channel so as to protect the well wall, and the water filter pipe (1-6) is arranged in the thermal reservoir well section (1-1).

5. The method for realizing sandstone geothermal well plugging removal based on gas-liquid mixture according to claim 1, characterized in that, The geothermal recharge well (1) further comprises a sand setting pipe (1-7) for setting sand, and the sand setting pipe (1-7) is arranged in the thermal reservoir well section (1-1).

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