Laser-dry ice jet combined rock breaking device and method

Abstract

The application discloses a laser-dry ice jet combined rock breaking device and method, which comprises two mechanical arms (102, 103) and laser cutting heads (203) and dry ice jet spray guns (302) arranged on the two mechanical arms (102, 103) respectively. In the rock breaking operation, the two mechanical arms (102, 103) drive the laser cutting heads (203) and the dry ice jet spray guns (302) to break rocks in front and back respectively. The application utilizes dry ice and laser to break rocks, and greatly improves the rock breaking capacity. First, the laser breaks rocks through the thermal cracking principle, and at the same time, the temperature of the rocks is raised. Then, the dry ice jet impacts the heated area. On the one hand, the impact force contained in the dry ice jet itself can cause the rock mass to break and can also take away the molten rock. On the other hand, the dry ice contacts the high-temperature rock, rapidly sublimates, causes local rapid cooling, and the rock mass is damaged due to the uneven heating and inconsistent shrinkage. When the dry ice sublimates, its volume expands by more than 800 times, and the "micro-explosion" effect further breaks the rock.

Description

Technical Field

[0001] This invention relates to the field of rock breaking, and more particularly to a laser-dry ice jet composite rock breaking device and method. Background Technology

[0002] As oil and gas field exploration technologies become increasingly sophisticated, extraction difficulties are gradually increasing. Traditional mechanical drilling methods are encountering bottlenecks, and in many complex working conditions, mechanical drilling is not even suitable. The maturing of laser technology has led to its increasing application in rock breaking. Summary of the Invention

[0003] This invention provides a laser-dry ice jet composite rock-breaking device and method, which combines the advantages of high-energy laser and dry ice jet, and utilizes the "micro-explosion" generated by thermal cycling and the impact and sublimation of dry ice particles to greatly improve rock-breaking ability.

[0004] According to a first aspect of the present invention, a laser-dry ice jet composite rock-breaking device is provided, comprising two robotic arms and a laser cutting head and a dry ice jet nozzle respectively mounted on the two robotic arms. During rock-breaking operations, the two robotic arms respectively drive the laser cutting head and the dry ice jet nozzle to move forward and backward along a trajectory to break the rock. From the starting point to the end point of the trajectory, the laser cutting head first emits a laser to break the rock using the principle of thermal fracturing, while simultaneously increasing the rock temperature. Subsequently, the dry ice jet nozzle emits dry ice particles to impact the heated area of ​​the rock. The laser cutting head and the dry ice jet nozzle hover after traveling a specific distance. The time interval t between the laser cutting head and the dry ice jet nozzle breaking the rock one after the other is 10 minutes. ′ for:

[0005]

[0006] In the formula, x is the distance between two adjacent hovering points; v is the walking speed; δ is the free margin; t is the hovering time each time, which is the time required from the start to the predetermined rock-breaking depth when using the high-energy laser emitted by the laser cutting head to break rocks at a fixed point.

[0007] Dry ice mass flow rate

[0008]

[0009] dry ice mass m:

[0010]

[0011] In the formula, K α K represents the rebound loss coefficient, which is related to the mass of the dry ice particles rebounding after impacting the target; βK represents the process loss coefficient, which is related to the mass of dry ice particles that sublimate before impacting the target during the incident process; r Q represents the increment coefficient, which relates to the additional mass of dry ice required to cool the rock below room temperature; m This indicates the latent heat of sublimation of dry ice;

[0012] The amount of heat Q absorbed by the rock to reach a specified temperature:

[0013] Q=ηPτ (4)

[0014] In the formula, η represents the efficiency of the rock in absorbing laser energy, P is the laser power, and τ is the interaction time.

[0015] According to a second aspect of the present invention, a laser-dry ice jet composite rock breaking method is provided. During rock breaking operations, a laser cutting head and a dry ice jet nozzle travel one after the other along a trajectory. From the starting point to the end point of the trajectory, the laser cutting head first emits a laser to break the rock using the principle of thermal fracturing, simultaneously increasing the rock temperature. Then, the dry ice jet nozzle emits dry ice particles to impact the heated area of ​​the rock. The laser cutting head and the dry ice jet nozzle hover after traveling a specific distance. The time interval t between the laser cutting head and the dry ice jet nozzle breaking the rock one after the other is... ′ for:

[0016]

[0017] In the formula, x is the distance between two adjacent hovering points; v is the walking speed; δ is the free margin; t is the hovering time each time, which is the time required from the start to the predetermined rock-breaking depth when using the high-energy laser emitted by the laser cutting head to break rocks at a fixed point.

[0018] Dry ice mass flow rate

[0019]

[0020] dry ice mass m:

[0021]

[0022] In the formula, K α K represents the rebound loss coefficient, which is related to the mass of the dry ice particles rebounding after impacting the target; β K represents the process loss coefficient, which is related to the mass of dry ice particles that sublimate before impacting the target during the incident process; r Q represents the increment coefficient, which relates to the additional mass of dry ice required to cool the rock below room temperature; m This indicates the latent heat of sublimation of dry ice;

[0023] The amount of heat Q absorbed by the rock to reach a specified temperature:

[0024] Q=ηPτ (4)

[0025] In the formula, η represents the efficiency of the rock in absorbing laser energy, P is the laser power, and τ is the interaction time.

[0026] In the first and / or second aspects mentioned above, after the laser cutting head and the dry ice jet gun break the rock along a trajectory, the dry ice jet gun and the laser cutting head return along the original trajectory to break the rock again.

[0027] In the first and / or second aspects mentioned above, the hovering starts from the starting point, hovering once every 2 days for hard rock mass and once every 4 days for soft rock mass, where d is the diameter of the high-energy laser spot emitted by the laser cutting head.

[0028] In the first and / or second aspects mentioned above, the rock-breaking depth is determined by an ultrasonic transmitting device.

[0029] In the first and / or second aspects described above, the high-energy laser emitted by the laser cutting head is a pulsed laser.

[0030] The present invention has the following beneficial effects:

[0031] 1. The combined use of dry ice and laser to break rocks significantly improves rock-breaking capabilities. First, the laser breaks the rock through thermal fracturing, while simultaneously increasing its temperature. Then, the dry ice jet impacts the heated area. On one hand, the impact force inherent in the dry ice jet itself can break the rock mass and remove molten rock. On the other hand, the dry ice rapidly sublimates upon contact with the high-temperature rock, causing localized rapid cooling. Uneven heating and inconsistent shrinkage of the rock mass lead to its destruction. Furthermore, the dry ice expands more than 800 times in volume during sublimation, creating a "micro-explosion" effect that further fragments the rock.

[0032] 2. The control system used in this invention employs ultrasonic waves to monitor the rock-breaking status in real time and feeds the rock-breaking information back to the control system. The control system adjusts the specific parameters of the dry ice jet and the high-energy laser in real time according to the preset rock-breaking model to ensure the highest efficiency of rock breaking at all times.

[0033] 3. A fully covered rock-breaking trajectory is presented, and under the condition of known laser power, the interval time t is given. ′ With dry ice mass flow rate The calculation method. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0035] Figure 1This is a schematic diagram of a dry ice laser composite rock breaking device provided in an embodiment of the present invention.

[0036] Figure 2 This is a schematic diagram of the rock-breaking trajectory provided in an embodiment of the present invention. Detailed Implementation

[0037] Laser rock breaking technology can precisely control the shape of the pores after rock breaking and improve the porosity and permeability of the pores and surrounding areas. It is a new type of non-destructive technology that can replace various conventional downhole operations such as reservoir completion, production enhancement, drilling, and wellbore construction. Ancient rock breaking capabilities were limited, so ingenious ancient people used the "thermal explosion method" to mine rocks. This involved heating the rock and then splashing cold water on it to cause it to crack, making it easier to mine. The laser-dry ice composite rock breaking technology mentioned in this invention utilizes modern technology to improve the "thermal explosion method." It can compensate for the shortcomings of single laser rock breaking while leveraging the advantages of laser rock breaking, further enhancing rock breaking capabilities. After the laser heats the rock mass, the dry ice jet impacts the heated area. On the one hand, the impact force inherent in the dry ice jet itself can cause rock fragmentation and remove some molten rock. On the other hand, when the dry ice comes into contact with the high-temperature rock mass, it rapidly sublimates, causing localized rapid cooling. Uneven heating and inconsistent shrinkage of the rock mass lead to its destruction. Furthermore, the dry ice expands in volume more than 800 times during sublimation, and the "micro-explosion" effect further fragments the rock.

[0038] Figure 1 A dry ice laser combined rock-breaking device is shown. For example... Figure 1 As shown, the dry ice laser composite rock breaking device includes a control unit 1, a high-energy laser generating unit 2, and a dry ice jet unit 3.

[0039] The control unit 1 includes a control system 101, robotic arms 102 and 103, and an ultrasonic transmitter 104.

[0040] The high-energy laser generating unit 2 includes a laser generator 201, a focusing lens 202, and a laser cutting head 203. The laser generator 201 can adjust the laser power, laser mode, energy density, etc. The focusing lens 202 is installed inside the laser cutting head 203 to focus the laser generated by the laser generator 201 onto the laser cutting head 203.

[0041] The dry ice jet unit 3 includes a dry ice accelerator 301 and a dry ice jet nozzle 302. The nozzle type of the dry ice jet nozzle 302 can be replaced according to actual needs; rectangular nozzles, circular nozzles, converging nozzles, Laval nozzles, or Helmholtz nozzles can be used. The dry ice accelerator 301 can adjust the dry ice jet air pressure and dry ice feed flow rate. The dry ice particles used by the dry ice accelerator 301 can have a diameter of 2mm, 3mm, or 4mm, and even block-shaped dry ice or snowflake-shaped dry ice can be used. The type of dry ice is selected according to the specific rock strata characteristics. For cold and brittle rock masses, dry ice sublimation quenching combined with laser heating is suitable for fracturing; small-diameter dry ice particles or snowflake-shaped dry ice can be used to enhance its sublimation ability. For rock masses easily subjected to impact fracturing, large-diameter dry ice particles or large-particle dry ice cut from block-shaped dry ice are used to enhance its impact performance, similar to an abrasive jet.

[0042] The ultrasonic transmitting device 104 monitors the rock-breaking process in real time and feeds back the rock-breaking depth to the control system 101. Then, the control system 101 adjusts the rock-breaking parameters based on the preset rock-breaking model.

[0043] Robotic arms 102 and 103, ultrasonic transmitter 104, laser generator 201, and dry ice accelerator 301 are all connected to and controlled by control system 101. Laser cutting head 203 and dry ice jet spray gun 302 are fixed to robotic arms 102 and 103 respectively. The two robotic arms 102 and 103 can control parameters such as the walking speed, walking direction, target distance, and incident angle of laser cutting head 203 and dry ice jet spray gun 302.

[0044] When performing rock-breaking operations, the robotic arms 102 and 103 of the dry ice laser composite rock-breaking device of the present invention move according to a preset trajectory. Starting from the starting point, the laser cutting head 203 first breaks the rock, followed by the dry ice jet spray gun 302, until the end position is reached. Then, the dry ice jet spray gun 302 returns along the original trajectory to break the rock, and the laser cutting head 203 then breaks the rock, until the starting point is reached.

[0045] Studies have shown that the main area affected by the laser rock-breaking thermal fracturing effect is a circular region with a radius of 4d centered at the laser's center point, where d is the diameter of the high-energy laser spot. Therefore, the main rock-breaking area is 4d away from the edge of the rock mass, and the distance from the bottom of the last rock-breaking trajectory to the bottom of the rock mass is a. It is sufficient to ensure that a is less than or equal to 4d. The preset rock-breaking trajectory is as follows: Figure 2 As shown.

[0046] In one embodiment, the normal travel speed of the laser cutting head 203 and the dry ice jet spray gun 302 is 5 mm / s, but it is not limited to this. The laser cutting head 203 and the dry ice jet spray gun 302 hover after traveling a certain distance. The hovering starts from the starting point; for hard rock, it hovers once every 2 days; for soft rock, it hovers once every 4 days. The hovering distance can be flexibly adjusted for different rock masses. The hovering time for each instance is t, which can be determined based on the rock breaking test. The rock breaking test involves using a high-energy laser to break rocks at a specific point; the time required from the start to reaching the predetermined rock breaking depth is t. The specific rock breaking depth is measured by the ultrasonic transmitting device 104.

[0047] Since the radius of the laser-induced thermally affected zone is 4d, after each trajectory is completed, the laser continues to travel downwards for a distance of 4d. To ensure efficient rock breaking, the longitudinal travel distance can be appropriately increased based on the actual rock mass properties.

[0048] The laser cutting head 203 and the dry ice jet gun 302 always break rocks one after the other, with an interval t between them. ′

[0049]

[0050] In the formula, x is the distance between two adjacent hovering points; v is the walking speed; and δ is the free margin. δ is intended to ensure that the laser cutting head 203 does not interfere with the dry ice jet gun 302; its value should be as small as possible and can be set according to actual conditions. The interval time is intended to ensure that the rock mass fully absorbs the laser energy or that the dry ice sufficiently cools the rock mass.

[0051] Studies have shown that pulsed waves are more effective at removing rock than continuous waves. Therefore, the high-energy laser used in this invention is a pulsed wave. Assuming the laser power is P and the action time is τ, the amount of heat Q absorbed by the rock to reach the specified temperature is...

[0052] Q=ηPτ (2)

[0053] In the formula, η represents the efficiency of the rock in absorbing laser energy.

[0054] The required dry ice mass m

[0055]

[0056] In the formula, K α K represents the rebound loss coefficient, which is related to the mass of the dry ice particles rebounding after impacting the target; β K represents the process loss coefficient, which is related to the mass of dry ice particles that sublimate before impacting the target during the incident process; r Q represents the incremental coefficient, which relates to the additional mass of dry ice required to lower the rock mass temperature below ambient temperature; m This indicates the latent heat of sublimation of dry ice.

[0057] The required dry ice mass flow rate is then set.

[0058]

[0059] The main area affected by the laser rock breaking thermal fracturing effect is a circular area with a radius of 4d centered on the center point, which is matched with a walking speed of 5mm / s. Changing the walking speed will change the main area affected by the thermal fracturing effect. The walking speed, longitudinal walking distance and hovering point position should be adjusted reasonably according to the actual situation.

Claims

1. A laser-dry ice jet composite rock-breaking method, characterized in that, During rock breaking operations, the laser cutting head and the dry ice jet gun move one after the other along a trajectory. From the beginning to the end of the trajectory, the laser cutting head first emits a laser to break the rock using the principle of thermal fracturing, while simultaneously increasing the rock temperature. Then, the dry ice jet gun emits dry ice particles to impact the heated areas of the rock. The laser cutting head and the dry ice jet gun hover at specific intervals after traveling a certain distance. The time interval between the laser cutting head and the dry ice jet gun breaking the rock one after the other is [not specified]. for: （1） In the formula, x is the distance between two adjacent hovering points; v is the walking speed; t represents the free margin; t is the hovering time for each time, which is the time required from the start to the predetermined rock-breaking depth when using the high-energy laser emitted by the laser cutting head to break rocks at a fixed point. Dry ice mass flow rate : （2） dry ice quality : （3） In the formula, This represents the rebound loss coefficient, which is related to the mass of the rebound after the dry ice particles impact the target point. This represents the process loss coefficient, which is related to the mass of dry ice particles that sublimate before impacting the target point during the incident process. This represents the increment factor, which relates to the additional mass of dry ice required to cool the rock below room temperature. This indicates the latent heat of sublimation of dry ice; The amount of heat Q absorbed by the rock to reach a specified temperature: （4） In the formula, This represents the efficiency of the rock in absorbing laser energy, where P is the laser power. This refers to the duration of action.

2. The laser-dry ice jet composite rock breaking method according to claim 1, characterized in that, After the laser cutting head and the dry ice jet gun break the rock along a trajectory, they return along the same trajectory to break the rock again.

3. The laser-dry ice jet composite rock-breaking method according to claim 1 or 2, characterized in that, The hovering starts from the starting point. For hard rock masses, the hovering occurs once every 2 days of travel, and for soft rock masses, the hovering occurs once every 4 days of travel, where d is the diameter of the high-energy laser spot emitted by the laser cutting head.

4. The laser-dry ice jet composite rock-breaking method according to claim 1 or 2, characterized in that, The rock-breaking depth was measured using an ultrasonic transmitter.

5. The laser-dry ice jet composite rock-breaking method according to claim 1 or 2, characterized in that, The high-energy laser emitted by the laser cutting head is a pulsed laser.

Images