WO2021189932A1

WO2021189932A1 - Plugging method

Info

Publication number: WO2021189932A1
Application number: PCT/CN2020/133205
Authority: WO
Inventors: 邵继新; 俞兆龙; 高胜友; 魏国平; 杨海鸿; 田斌守; 司双龙; 徐民盛; 王玺
Original assignee: 甘肃省建材科研设计院有限责任公司
Priority date: 2020-03-27
Filing date: 2020-12-02
Publication date: 2021-09-30
Also published as: CN111395992A

Abstract

A plugging method, applied to a mid-deep strata geothermal well (6), and comprising: removing soil of a leakage area, and adding backfill soil and compacting same to form a backfill soil layer (4); drilling at leakage points of the leakage area to form at least one grouting hole (9) and at least one exhaust hole (5); inserting a grouting pipe (10) into the grouting hole, and injecting a plugging material to a position below the backfill soil layer by means of the grouting pipe; plugging the exhaust hole, and injecting a plugging material to be the position below the backfill soil layer again; and standing for a preset time to complete the plugging. The plugging material is injected by adopting a low-pressure method, the operation is simple, and the leakage points are plugged more effectively by injecting the plugging material twice.

Description

Plugging method

Technical field

The invention relates to the technical field of plugging materials, in particular to a method for plugging.

Background technique

The medium-deep geological heat utilization technology is a clean heating technology developed in recent years under the background of my country's energy reform and ecological protection. Drill a hole, install a closed metal heat exchanger in the hole, conduct through the heat exchanger, and carry out the non-interference conversion of the deep underground geothermal energy with a temperature of 70°C to 120°C. A new technology for special equipment systems to supply heat to buildings on the ground. This technology has the characteristics of continuous and stable heat extraction, fast recovery of ground temperature, and low environmental impact. It has become a globally recognized clean energy with great application value and utilization potential.

Lost circulation is one of the most common and frequently encountered complex problems during drilling operations and well operations. In the actual application of the medium-deep geothermal heating technology, deep wells must be drilled underground. When the deep well encounters underground confined water, it will cause the confined water to flow along the gap between the metal heat exchanger and the well wall during construction and later use. This will cause problems such as water leakage in the well, low heat exchange efficiency, and endangerment of the life of the metal heat exchanger. It is difficult to accurately grasp the position and structure of the confined water strata in the mid-deep geological thermal wells, and it is difficult to use mature oil well bridge plugging methods. In order to solve the above-mentioned mid-deep geothermal wells The problem of backwater leakage on pressurized water. The present invention uses the method of low-pressure infusion of the quick-setting waterproof slurry and specific drainage for leak-stopping construction, so as to solve the problem of backwater leakage during the construction and operation of medium-deep geothermal wells. The development of geothermal energy provides safety guarantee and technical support.

Summary of the invention

The purpose of the present invention is to provide a leakage plugging method, which is convenient to select by using ordinary cement slurry as a material, and low-pressure method is used for pouring during construction, which is simple and safe to operate, and can quickly and conveniently solve the problem of water leakage in deep geothermal wells.

In order to solve the above technical problems, according to the present invention, a leak plugging method is provided, which is applied to middle-deep geological hot wells, including:

Remove the soil in the seepage area of the mid-deep geological hot well, and add backfill soil to ram it to form a backfill soil layer;

Drill holes at the leakage point of the leakage area to form at least one grouting hole and at least one vent hole;

Insert a grouting pipe into the at least one grouting hole, so as to inject the plugging material under the backfill soil layer through the grouting pipe;

Sealing the at least one vent hole, and again injecting the leakage plugging material below the backfill soil layer;

Let it stand for a preset time to complete the leak plugging of the mid-deep geological thermal well.

Further, the backfill soil includes lime and soil in a preset ratio, and the backfill soil layers are multiple layers, and the thickness of each backfill soil layer is less than or equal to the preset thickness.

Further, the length of the grouting pipe is greater than the thickness of the backfill soil layer, and at least one opening is provided at one end of the grouting pipe extending below the backfill soil layer.

Further, the step of inserting a grouting pipe into the at least one grouting hole, and injecting a plugging material into the backfill soil layer through the grouting pipe includes:

Turn on the pressurizing device to make the pressure injected into the plugging material reach the first preset grouting pressure;

When the plugging material flows out through the at least one vent hole, the pressurizing device is closed and the injection of the plugging material is stopped.

Further, the step of plugging the at least one vent hole and injecting the plugging material below the backfill soil layer again includes:

Using a plugging device to plug the at least one vent hole;

Turn on the pressurizing device so that the pressure of the plugging material injected exceeds the second preset grouting pressure;

When the change value of the pressure injected into the plugging material reaches a preset change value, the pressurizing device is closed and the injection of the plugging material is stopped.

Further, the step of standing for a preset time to complete the leak plugging of the mid-deep geological thermal well includes:

When the water output temperature of the mid-deep geological thermal well is less than or equal to the first preset temperature, after the injection of the plugging material is completed, the preset time is greater than or equal to the first preset time;

When the water output temperature of the mid-deep geological thermal well is greater than the first preset temperature and less than or equal to the second preset temperature, after the injection of the plugging material is completed, the preset time is greater than or equal to the second Preset time.

Further, the plugging material includes a base slurry formed by mixing cement and water, as well as a quick-setting agent and a waterproofing agent.

Compared with the prior art, the present invention has obvious advantages and beneficial effects. With the above technical solutions, a leak plugging method of the present invention can achieve considerable technological advancement and practicability, and has a wide range of industrial use value. It has at least the following advantages:

(1) By using ordinary Portland cement, it is convenient to select materials and effectively reduces the production cost of plugging materials.

(2) The low-pressure method is used to inject the plugging material, which is simple to operate and can effectively ensure the safety of the operators during the plugging process.

(3) By injecting the plugging material twice, the leakage point can be sealed more effectively.

The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly, it can be implemented in accordance with the content of the specification, and in order to make the above and other objectives, features and advantages of the present invention more obvious and understandable. , The following is a specific example of a preferred embodiment, in conjunction with the accompanying drawings, the detailed description is as follows.

Description of the drawings

Fig. 1 shows a flow chart of a leak plugging method according to an embodiment of the present invention;

Fig. 2 shows a schematic diagram of the application of plugging in a medium-deep geothermal well according to an embodiment of the present invention.

【Symbol Description】

1: Observation well

2: Water supply pipe

3: Return pipe

4: Backfill soil layer

5: Exhaust and drainage holes

6: Geothermal well

7: Outer tube

8: Inner casing

9: Grouting hole

10: Grouting steel pipe

11: Pulp hole

12: Pressurizing device

Detailed ways

In order to further illustrate the technical means and effects of the present invention to achieve the intended purpose of the invention, the following describes in detail the specific implementation and effects of a leak plugging method proposed in accordance with the present invention with reference to the accompanying drawings and preferred embodiments. As later.

The embodiment of the present invention provides a leakage plugging method, which is applied to a mid-deep geological thermal well, and the method includes:

In step S102, the soil in the leakage area of the middle-deep geological hot well is removed, and backfilled soil is added for ramming to form a backfilled soil layer.

Specifically, the above-mentioned seepage area refers to an area soaked by the seepage water within a preset radius centered on the middle-deep geological thermal well according to the amount of water leakage. The greater the amount of water leakage, the greater the above-mentioned radius.

After removing the soil soaked by the seepage water in the seepage area, add backfilling soil to the seepage area after removing the soil and tamping it. The backfill is made by mixing lime and soil with a preset ratio to ensure the firmness of the backfill being compacted. The preset ratio is the weight ratio of lime to soil. Preferably, the preset ratio is 3:7, that is, three parts of lime and seven parts of soil are mixed.

In order to further ensure the firmness and tightness of the backfill soil layer, the backfill soil layer is multi-layered, that is, the backfill soil is compacted in layers, and the thickness of each backfill soil layer is less than or equal to the preset thickness. Preferably, the preset thickness is 250 mm.

Step S104: Drill a hole at the leakage point in the leakage area to form at least one grouting hole and at least one vent hole.

Specifically, when there is leakage in the middle-deep geological thermal well, there will be multiple leaking channels around the middle-deep geological thermal well. The location of the leaking channel is the leakage point. Drill holes, at least one of the formed holes is used as a grouting hole, and the remaining holes are used as vent holes. Preferably, there are no less than three openings, one of which is used as a grouting hole, and the remaining openings are used as vent holes. In order to facilitate the smooth injection of the plugging material, the diameter of the opening is not less than 50 mm.

Step S106: Insert a grouting pipe into at least one grouting hole, so as to inject the plugging material under the backfill soil layer through the grouting pipe.

Specifically, in order to smoothly inject the plugging material below the backfill soil layer, a grouting pipe is inserted into the grouting hole, and the grouting pipe is inserted below the backfill soil layer. The diameter of the grouting pipe matches the diameter of the grouting hole, that is, the outer diameter of the grouting pipe is equal to the diameter of the grouting hole, or the outer diameter of the grouting pipe is slightly larger than the diameter of the grouting hole.

In order to prevent the grouting pipeline from cracking due to excessive pressure during the grouting process, steel pipes are preferably used for the grouting pipeline.

In order to prevent the mud from blocking the opening of the grouting pipe extending into the backfill layer during the process of inserting the grouting pipe into the grouting hole, at least one opening is provided at the end of the grouting pipe extending below the backfill soil layer to block the grouting pipe. Leaking material can flow out through the at least one opening. Preferably, the diameter of the opening is not less than 20 mm, and the plurality of openings are distributed in a plum blossom shape.

After the grouting pipe is inserted, the plugging material is introduced into one end of the grouting pipe so that the plugging material can flow into the soil under the backfill. In order to enable the plugging material to smoothly enter the soil below the backfill layer, the grouting is pressurized by a pressurizing device. It is known that if excessive pressure is suddenly applied during the grouting process, the plugging material will not penetrate well into the soil and will be ejected through the vent. Therefore, it is necessary to control the pressurizing device to slowly pressurize, and stop pressurizing when the pressurization reaches the first preset grouting pressure. Then, the first preset grouting pressure is used to pressurize the grouting. When the injected plugging material flows out through the vent hole, it indicates that the plugging material has been unable to penetrate into the soil. At this time, the pressurizing device is closed and the injection of the plugging material is stopped. Preferably, the first preset grouting pressure is 0.2 MPa, and the pressurizing device is an air machine.

The plugging material can be a base slurry that is mixed with cement and water, and a waterproofing agent and an accelerator are added to the base slurry. In order to improve the waterproof effect of the plugging material, and increase the solidification speed of the plugging material. Both the waterproofing agent and the quick-setting agent can be made of common materials, which will not be repeated here.

In step S108, at least one vent hole is plugged, and a plugging material is injected below the backfill soil layer again.

Specifically, in order to be able to inject more plugging materials into the soil under the backfilled soil layer to ensure the plugging effect. Block all vent holes to ensure airtightness and prevent leaking materials from flowing out. The vent hole can be blocked by a steel cone prepared in advance, and a counterweight is also arranged under the cone to ensure the blocking effect. At the same time, tape or hot melt adhesive can be used to seal the contact between the cone and the backfill.

After completing the plugging of the vent hole, grouting is carried out under the backfill soil layer again through the grouting pipe, and the pressurizing device is turned on, and the grouting pressure is slowly adjusted to above the second preset grouting pressure through the pressurizing device. And make the grouting pressure continue to increase until the change value of the pressure of the injected plugging material reaches the preset change value, indicating that the plugging material has been unable to penetrate into the soil. At this time, close the pressurizing device and stop the injection of the plugging material.

The above-mentioned preset change value can be 0 or a small change value, that is, the pressure of the injection plugging material no longer increases or increases very slowly.

Step S110, standing for a preset time to complete the plugging of the middle-deep geological thermal well.

Specifically, after stopping the injection of the plugging material, it is allowed to stand for a preset time, and the plugging work is completed after the standing has been completed.

The solidification time of the plugging material will be different according to the temperature of the water in the middle and deep geological thermal wells. Therefore, the corresponding standing time is set according to the temperature of the water in the middle and deep geological thermal wells.

When the water outlet temperature of the middle-deep geological thermal well is less than or equal to the first preset temperature, after the plugging material is injected, the preset time is greater than or equal to the first preset time;

When the water outlet temperature of the mid-deep geothermal well is greater than the first preset temperature and less than or equal to the second preset temperature, after the plugging material is injected, the preset time is greater than or equal to the second preset time.

Fig. 2 shows a schematic diagram of the application of plugging in a medium-deep geothermal well according to an embodiment of the present invention. As shown in Figure 2, a heat exchange component is installed in the deep geothermal well 6 to extract underground heat energy. The heat exchange component includes an outer casing 7 and an inner casing 8, wherein the outer casing 7 is connected to the return pipe 3, and the inner The sleeve 8 is connected to the water supply pipe 2. After the construction and installation of the deep geothermal well 6 and the underground heat exchanger are completed, due to the action of underground confined water, water leakage occurs around the outer casing 7 and the geothermal well 6, which brings safety to the operation of the geothermal well 6 Hidden dangers.

After water leakage occurs in the geothermal well 6, the leakage is stopped through the following steps, including:

Step 1: First, configure specific plugging materials according to the amount of water leakage. The plugging materials are mainly ordinary cement, and appropriate amount of quick-setting agent and waterproofing agent are added according to the temperature conditions.

Step 2: Center the geothermal well 6 and dig down the soil within a radius of at least two meters to dig out all the soil or mud soaked in water, and then use 3:7 (ie, the preset ratio) of lime and The soil is mixed to form a backfill, which is compacted and backfilled in layers, each with a thickness of 250mm (ie the preset thickness), and backfilled to the ground plane of the geothermal well, forming a layered backfill 4;

Step 3: Drill down at the location (ie, leakage point) where the water outlet channel may be formed around the geothermal well 6 with no less than three holes (two openings are shown in the figure), and open holes The diameter is not less than 50mm, one of the holes is the grouting hole 9, and the other holes are used for the exhaust and drainage holes 5 (that is, the exhaust holes) during grouting to ensure that the injected plugging material is dense.

Step four, choose the grouting steel pipe 10 (ie grouting pipe) that matches the diameter of the grouting hole 9, and its length is not less than the depth of the backfill soil layer 4, in order to prevent the bottom of the grouting steel pipe 10 from being clogged with soil and unable to grouting. Grouting holes 11 (ie, openings) with a diameter of not less than 20 mm are opened on the end side wall of the grouting steel pipe 10, which are arranged in a plum blossom shape.

Step 5, first pour the configured leak-proofing material into the grouting steel pipe 10, one end of the grouting steel pipe 10 is connected with the pressurizing device 12, and the other end goes deep into the lower soil around the geothermal well 6 through the grouting hole 9.

Step 6. When grouting is started, slowly open the control valve of the pressurizing device 12, and when the pressure reaches 0.2MPa (that is, the first preset grouting pressure), the pressurization is stopped, and the leak-stopping material enters the backfill through the grouting hole 9 Below layer 4, with the inflow of the leak-proofing material, the water and air around the geothermal well 6 begin to drain through the exhaust and drainage hole 5, until the leak-proofing material flows out from the exhaust and drainage hole 5, close the control valve of the pressurizing device 12 , Stop filling the plugging material.

Step 7: Block all the exhaust and drainage holes 5 with a steel cone prepared in advance. Place a counterweight above the steel cone. At the same time, wrap the grouting steel pipe 10 in contact with the backfill soil layer 4 with tape to make They are in close contact, and then the plugging material is re-injected into the grouting steel pipe 10, the control valve of the pressure device 12 is opened, and the second pressure grouting is performed, and the pressure is slowly adjusted to 2Mpa (that is, the second preset grouting pressure ) Above, close the valve after the pressure stabilizes, and the grouting ends.

Step 8. If the outlet temperature of the underground confined water (ie the outlet temperature of the mid-deep geological thermal well) is less than or equal to 50℃ (ie the first preset temperature), the plugging material is injected and allowed to stand for no less than 8h (ie the first preset Time), if the outlet temperature of underground pressurized water is 50-80℃ (ie the second preset temperature), and the standing time is not less than 4h (ie the second preset time), leave an exhaust and drainage hole 5 for observation, and close it Grouting hole 9 and other exhaust and drainage holes 5.

In the above operation, the inspection well 1 should be well illuminated and well ventilated, and the side walls of the inspection well 1 should be solid and firm to ensure the safety of construction.

According to the actual plugging construction needs, the depth of the backfill 4 is determined by the amount of water leakage and the surrounding soil quality of the geothermal well 6. The number of grouting holes 9 and drainage holes 5 can be determined according to the amount of plugging material injected and the amount of drainage. Limited to the number mentioned above.

In combination with the above-mentioned embodiments, in the plugging method of the present invention, ordinary cement is added with quick-setting agent and waterproofing agent to configure the plugging material, and the low-pressure infusion method is used to inject the plugging material around the geothermal well to ensure that the plugging material is pumped into the groundwater bottom layer. After the cracks, it can quickly condense. After standing for a certain period of time according to different formation temperatures, the plugging material will be dense and completely solidified underground, which can offset the pressure of underground confined water, thereby preventing underground confined water backflow around geothermal wells. water leakage.

The above are only the preferred embodiments of the present invention, and do not limit the present invention in any form. Although the present invention has been disclosed in the preferred embodiments as above, it is not intended to limit the present invention. Anyone familiar with the profession Those skilled in the art, without departing from the scope of the technical solution of the present invention, can use the technical content disclosed above to make slight changes or modifications to equivalent embodiments with equivalent changes, but any content that does not depart from the technical solution of the present invention is based on the present invention Any simple modifications, equivalent changes and modifications made to the above embodiments are still within the scope of the technical solutions of the present invention.

Claims

A leak plugging method, characterized in that it is applied to a mid-deep geological thermal well, and the method includes:

Remove the soil in the seepage area of the mid-deep geological hot well, and add backfill soil to ram it to form a backfill soil layer;

Drill holes at the leakage point of the leakage area to form at least one grouting hole and at least one vent hole;

Insert a grouting pipe into the at least one grouting hole, so as to inject the plugging material under the backfill soil layer through the grouting pipe;

Sealing the at least one vent hole, and again injecting the leakage plugging material below the backfill soil layer;

Let it stand for a preset time to complete the leak plugging of the mid-deep geological thermal well.
The plugging method according to claim 1, wherein the backfill soil comprises lime and soil in a preset ratio, and

The backfill soil layer has multiple layers, and the thickness of each backfill soil layer is less than or equal to a preset thickness.
The leak plugging method according to claim 1, wherein the length of the grouting pipe is greater than the thickness of the backfill soil layer, and

At least one opening is provided at one end of the grouting pipe extending below the backfill soil layer.
The method of plugging according to claim 1, wherein a grouting pipe is inserted into the at least one grouting hole, and the plugging material is injected into the backfill below the backfill through the grouting pipe. The steps include:

Turn on the pressurizing device to make the pressure injected into the plugging material reach the first preset grouting pressure;

When the plugging material flows out through the at least one vent hole, the pressurizing device is closed and the injection of the plugging material is stopped.
The leak plugging method according to claim 4, wherein the step of plugging the at least one vent hole and injecting the plugging material below the backfill soil layer again comprises:

Using a plugging device to plug the at least one vent hole;

Turn on the pressurizing device so that the pressure of the plugging material injected exceeds the second preset grouting pressure;

When the change value of the pressure injected into the plugging material reaches a preset change value, the pressurizing device is closed and the injection of the plugging material is stopped.
The leak plugging method according to claim 1, wherein the step of standing for a preset time to complete the leak plugging of the middle-deep geological thermal well comprises:

When the water output temperature of the mid-deep geological thermal well is less than or equal to the first preset temperature, after the injection of the plugging material is completed, the preset time is greater than or equal to the first preset time;

When the water output temperature of the mid-deep geological thermal well is greater than the first preset temperature and less than or equal to the second preset temperature, after the injection of the plugging material is completed, the preset time is greater than or equal to the second Preset time.
The method of plugging according to claim 1, wherein the plugging material comprises a base slurry formed by mixing cement and water, as well as a quick-setting agent and a waterproofing agent.