Air lift reverse circulation hole cleaning method for ultra-deep guide hole

Abstract

The invention discloses a gas lift reverse circulation hole cleaning method for an ultra-deep guide hole. The gas lift reverse circulation hole cleaning method comprises the following steps that firstly, a double-wall drill rod, a gas-liquid mixing device and a single-wall drill rod are sequentially arranged from top to bottom; 2, clear water is injected into the annulus of the shaft and the double-wall drill rod, and the liquid level is kept stable; thirdly, compressed air is injected into an annular space in the double-wall drill rod, a hole is formed in the side edge of the single-wall drill rod, the air moves upwards in the inner wall of the single-wall drill rod, and negative pressure is formed; and fourthly, negative pressure is formed in the double-wall drill rod, water is continuously injected to the outer side, the liquid level height is kept, circulation is established, under the combined action of the internal and external water pressure difference and compressed air, a gas-liquid-solid mixture in the guide hole is brought out along a center hole of the double-wall drill rod, and the guide hole cleaning work is completed. And sediment in the hole is reduced, efficient and rapid hole cleaning is achieved, and next reaming drilling is facilitated.

Description

Technical Field

[0001] The present invention belongs to the technical field of drilling, and specifically relates to a method for air-lift reverse circulation hole cleaning of ultra-deep guide holes. Background Art

[0002] Ultra-deep large-diameter directional drilling technology is a necessary way to form a rescue hole in the field of drilling rescue. Drilling rescue should have the advantages of long distance, high efficiency, high speed, non-direct contact, etc., and is widely used in the emergency rescue of mine accident disasters. With the continuous increase of ultra-deep and ultra-intense mining of mineral resources, the underground geological conditions have become more complex. To ensure the smooth lowering of the rescue lift, the diameter and depth of the rescue hole are getting larger and larger. The diameter requirement is ≥580mm, the hole depth is ≥800m, and the requirement for hole forming accuracy is also becoming more and more strict. The technology for directly forming an ultra-deep large-diameter rescue hole is not yet perfect, and it is necessary to construct a small-diameter guide hole by directional construction, and then use the large-diameter reverse circulation DTH hammer reaming drilling technology to finally form the hole. During reaming drilling, cuttings are likely to fall into the small-diameter guide hole and accumulate, affecting the next rescue construction, so it is necessary to clean the hole in a timely and efficient manner.

[0003] A large number of research works have been carried out on the problem of hole cleaning at home and abroad, but mainly for large-diameter bored cast-in-place piles. The hole forming depth of such holes is relatively shallow. At present, the main methods for cleaning the holes of bored cast-in-place piles are the positive circulation flushing method and the pump suction reverse circulation. The positive circulation flushing method has the disadvantages of long hole cleaning time and unsatisfactory effect, and the pump suction reverse circulation is only used for the pile holes constructed by the pump suction reverse circulation method. The mainstream method for cleaning the ultra-deep guide hole is the positive circulation hole cleaning process. This method takes a long time and it is very difficult to clean the bottom sediment of the hole completely. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a method for air-lift reverse circulation hole cleaning of ultra-deep guide holes.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A method for air-lift reverse circulation hole cleaning of ultra-deep guide holes, comprising the following steps:

[0007] Step 1: Sequentially lower the double-wall drill pipe, the gas-liquid mixing device, and the single-wall drill pipe from top to bottom;

[0008] Step 2: Inject clear water into the annulus between the wellbore and the double-wall drill pipe to keep the liquid level stable;

[0009] Step 3: Inject compressed air into the annulus in the double-wall drill pipe, open holes on the side of the single-wall drill pipe, so that the air moves upward along the inner wall of the single-wall drill pipe to form a negative pressure;

[0010] Step 4: Create a negative pressure inside the double-wall drill pipe, continuously inject water outside, maintain the liquid level height, establish a circulation, and under the combined action of the internal and external water pressure difference and compressed air, bring out the gas-liquid-solid mixture in the pilot hole along the central hole of the double-wall drill pipe to complete the cleaning of the pilot hole.

[0011] Preferably, in Step 1, the single-wall drill pipe is arranged in the pilot hole, and the double-wall drill pipe and the gas-liquid mixing device are both arranged in the wellbore.

[0012] Preferably, in Step 2, the liquid level height is at least above the gas-liquid mixing device.

[0013] Preferably, in Step 3, the bottom of the double-wall drill pipe is sealed and connected to the top of the gas-liquid mixing device.

[0014] Preferably, in Step 4, the gas-liquid-solid mixture entrains rock cuttings.

[0015] Preferably, in Step 4, the water injection volume is equivalent to the discharged liquid volume to keep the liquid level in the large hole stable.

[0016] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows:

[0017] In the present invention, by injecting compressed air and clean water, negative pressure is generated by gas-liquid mixing to carry the rock cuttings in the pilot hole upward for hole cleaning. The required equipment and materials are simple. Water is injected into the outer annulus between the double-wall drill pipe and the wellbore, and compressed air is injected into the inner annulus of the double-wall drill pipe. A gas-liquid mixture with a density less than that of water is formed in the gas-liquid mixing device. Under the combined action of the water pressure difference and high-pressure air, it rises along the central hole of the drill pipe and drives the rock cuttings deposited at the bottom of the pilot hole to flow upward, forming a three-phase flow of air, water, and rock cuttings. Continuously inject water into the hole and inject gas into the annulus of the double-wall drill pipe, thereby establishing a reverse circulation with stable flow velocity and flow rate, and carrying the sediment to rise from the pilot hole. It effectively improves the hole cleaning efficiency, reduces the sediment in the hole, realizes efficient and rapid hole cleaning, and facilitates the next step of reaming drilling. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the equipment installation of a method for air-lift reverse circulation hole cleaning of an ultra-deep pilot hole according to the present invention.

[0019] Reference numerals: 1. Double-wall drill pipe; 2. Gas-liquid mixing device; 3. Single-wall drill pipe; 4. Pilot hole. DETAILED DESCRIPTION OF THE INVENTION

[0020] The following details the specific embodiments of the present invention.

[0021] The "range" disclosed by the present invention is defined in the form of a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of a particular range. The ranges defined in this way can include the end values or not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range. For example, if a range of 10-50 is listed for a specific parameter, ranges of 10-40 and 20-50 are also contemplated. In addition, if the minimum range values 1 and 2 are listed, and if the maximum range values 3, 4, and 5 are listed, then the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise specified, the numerical range "a-b" represents an abbreviated representation of any real number combination between a and b, where both a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been fully listed herein, and "0-5" is only an abbreviated representation of these numerical combinations.

[0022] If there is no special instruction, all embodiments and optional embodiments of this application can be combined with each other to form a new technical solution.

[0023] If there is no special instruction, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0024] If there is no special instruction, all steps of this application can be carried out in sequence or randomly, preferably in sequence. For example, the method includes steps (a) and (b), which means that the method can include steps (a) and (b) carried out in sequence, or can also include steps (b) and (a) carried out in sequence. For example, it is mentioned that the method may further include step (c), which means that step (c) can be added to the method in any order. For example, the method can include steps (a), (b), and (c), or can also include steps (a), (c), and (b), or can also include steps (c), (a), and (b), etc.

[0025] If there is no special instruction, the "including" and "comprising" mentioned in this application mean open-ended, and can also be closed-ended. For example, the "including" and "comprising" can mean that other components not listed can also be included or comprised, or can only include or comprise the listed components.

[0026] If there is no special instruction, the reaction is carried out under normal temperature and normal pressure conditions.

[0027] If there is no special instruction, all parts or percentages are parts by weight or percentages by weight.

[0028] In the present invention, all the substances used are known substances, which can be purchased or synthesized by known methods.

[0029] In the present invention, all the devices or equipment used are conventional devices or equipment known in the field, and can be purchased.

[0030] The following further illustrates the specific implementation manners of a super-deep guide hole air-lift reverse circulation hole cleaning method of the present invention in conjunction with embodiments. The super-deep guide hole air-lift reverse circulation hole cleaning method of the present invention is not limited to the descriptions of the following embodiments.

[0031] Embodiment 1:

[0032] A super-deep guide hole air-lift reverse circulation hole cleaning method, as Figure 1 shown, includes the following steps:

[0033] Step 1: Sequentially lower the double-wall drill pipe 1, the gas-liquid mixing device 2, and the single-wall drill pipe 3 from top to bottom;

[0034] Step 2: Inject clear water into the annulus between the wellbore and the double-wall drill pipe 1, and keep the liquid level stable;

[0035] Step 3: Inject compressed air into the annulus in the double-wall drill pipe 1, and open holes on the side of the single-wall drill pipe 3 so that the air moves upward along its inner wall to form a negative pressure;

[0036] Step 4: A negative pressure is formed in the double-wall drill pipe 1, and water is continuously injected outside to keep the liquid level height, and a circulation is established. Under the combined action of the internal and external water pressure differences and the compressed air, the gas-liquid-solid mixture in the guide hole 4 is carried out along the central hole of the double-wall drill pipe 1 to complete the hole cleaning work of the guide hole 4.

[0037] In a possible implementation manner, in Step 1, the single-wall drill pipe 3 is arranged in the guide hole 4, and the double-wall drill pipe 1 and the gas-liquid mixing device 2 are both arranged in the wellbore.

[0038] In a possible implementation manner, in Step 2, the liquid level height is at least above the gas-liquid mixing device 2.

[0039] In a possible implementation manner, in Step 3, the bottom of the double-wall drill pipe 1 is hermetically connected to the top of the gas-liquid mixing device 2.

[0040] In a possible implementation manner, in Step 4, the gas-liquid-solid mixture entrains cuttings.

[0041] In a possible implementation manner, in Step 4, the water injection volume is equivalent to the discharged liquid volume to keep the liquid level in the large hole stable.

[0042] Embodiment 1:

[0043] A super-deep guide hole air-lift reverse circulation hole cleaning method, as Figure 1As shown in the figure, it includes the following steps:

[0044] Step 1: Assemble the drill string. From top to bottom, there are a double-wall drill pipe 1, a gas-liquid mixing device 2, and a single-wall drill pipe 3 in sequence. The single-wall drill pipe 3 should be placed inside the guide hole 4.

[0045] Step 2: Inject water. Inject clear water into the annulus between the wellbore and the double-wall drill pipe 1, and keep the liquid level stable. The liquid level height should be at least above the gas-liquid mixing device 2.

[0046] Step 3: Inject gas. Inject compressed air into the annulus in the double-wall drill pipe 1. The bottom of the double-wall drill pipe 1 is connected and sealed with the gas-liquid mixing device 2, and openings are made on the side so that the air moves upward along the inner wall, forming a negative pressure.

[0047] Step 4: A negative pressure is formed inside the double-wall drill pipe 1, and water is continuously injected outside while keeping the liquid level height to establish a circulation. Under the combined action of the internal and external water pressure difference and the compressed air, the gas-liquid-solid mixture (entraining cuttings) in the guide hole 4 can be carried out along the central hole of the double-wall drill pipe 1. This is the air-lift reverse circulation process to complete the hole cleaning work of the guide hole.

[0048] Furthermore, the gas-liquid mixing device must be placed below the liquid level.

[0049] Furthermore, pay attention to continuously injecting water, and the injection volume of water should be equivalent to the discharged liquid volume to keep the liquid level stable in the large hole.

[0050] By adopting the above technical solutions:

[0051] In this application, clear water is injected into the annulus, compressed air is injected into the central hole of the drill pipe, a gas-liquid mixture is generated to form a negative pressure, and the cuttings in the guide hole 4 are carried back to the ground in reverse circulation along the inner wall of the drill pipe. This air-lift reverse circulation hole cleaning method has the following advantages: 1. Short time and high efficiency; 2. The bottom sediment of the hole is cleaned thoroughly, which is beneficial to the next step of enlarging the rescue hole for drilling, so as to achieve the purpose of safe, fast and efficient rescue.

[0052] This application is a method for hole cleaning by injecting compressed air and clear water, mixing gas and liquid to generate a negative pressure, and carrying the cuttings in the guide hole upward. The required equipment and materials are simple. Inject water into the outer annulus between the double-wall drill pipe and the wellbore, inject compressed air into the inner annulus of the double-wall drill pipe, form a gas-liquid mixture with a density less than that of water in the gas-liquid mixing device, rise along the central hole of the drill pipe under the combined action of the water pressure difference and high-pressure air, and drive the cuttings deposited at the bottom of the guide hole to flow upward, forming a three-phase flow of air, water and cuttings, and continuously injecting water into the hole and injecting gas into the annulus of the double-wall drill pipe, so as to establish a reverse circulation with stable flow velocity and flow rate and carry the sediment up from the guide hole.

[0053] Compared with the prior art, in view of the problems of long time consumption in the conventional positive circulation hole cleaning and incomplete cleaning of ultra-deep holes, the present invention provides a method for air-lift reverse circulation hole cleaning in ultra-deep guiding holes, which effectively improves the hole cleaning efficiency, reduces the sediment in the hole, realizes efficient and rapid hole cleaning, and facilitates the next step of reaming drilling.

[0054] The above content is a further detailed description of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can be made, which should all be regarded as belonging to the protection scope of the present invention.

Claims

1. An ultra-deep pilot hole air lift reverse circulation hole cleaning method, characterized in that: The following steps are involved: Step 1: sequentially assemble the double-wall drill pipe (1), the gas-liquid mixing device (2), and the single-wall drill pipe (3) from top to bottom; Step 2: inject clean water into the annulus between the wellbore and the double-wall drill pipe (1) to keep the liquid level stable; Step 3: Inject compressed air into the annulus of the double-wall drill pipe (1), and open a hole on the side of the single-wall drill pipe (3) so that the air moves upward along its inner wall to form a negative pressure; Step 4: Negative pressure is formed inside the double-wall drill pipe (1), and water is continuously injected from the outside to maintain the liquid level and establish circulation. Under the combined effect of the internal and external water pressure difference and compressed air, the gas-liquid-solid mixture in the guide hole (4) is brought out along the center hole of the double-wall drill pipe (1), completing the cleaning of the guide hole (4).

2. The method for cleaning an ultra-deep pilot hole by gas lift reverse circulation as claimed in claim 1, characterized in that: In the step 1, the single-wall drill pipe (3) is arranged in the guide hole (4), and the double-wall drill pipe (1) and the gas-liquid mixing device (2) are both arranged in the wellbore.

3. The method for cleaning an ultra-deep pilot hole by gas lift reverse circulation as claimed in claim 1, characterized in that: In the step 2, the liquid level is at least higher than the gas-liquid mixing device (2).

4. The method for cleaning an ultra-deep pilot hole by gas lift reverse circulation as claimed in claim 1, characterized in that: In the step three, the bottom of the double-wall drill pipe (1) is sealed and connected to the top of the gas-liquid mixing device (2).

5. The method for cleaning an ultra-deep pilot hole by gas lift reverse circulation as claimed in claim 1, characterized in that: In step 4, the gas-liquid-solid mixture entrains rock cuttings.

6. The method for cleaning an ultra-deep pilot hole by gas lift reverse circulation as claimed in claim 1, characterized in that: In the step 4, the amount of water injected is equal to the amount of liquid discharged, so as to keep the liquid level in the macropore stable.

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