CN108709541A - A kind of ocean platform sea ice monitoring devices and methods therefor - Google Patents

Abstract

The invention discloses a kind of ocean platform sea ice monitoring devices and methods therefors.Video monitor passes through formula：h_i=H_Diameter*T/Dh obtains sea ice thickness；Wherein, H_Diameter is the aperture for demarcating the wave resistance hole that object is cone, and T is the ice section pixel size on image, and Dh is to demarcate the wave resistance hole that object is cone, and aperture H_Diameter is 20cm, pixel size on the image；Video monitor passes through formula：v_i=Hs/ (ht) obtains sea ice speed；Wherein, H is the lens of video camera and real-world object distance is, s be image on length in pixels, h be video camera lens at a distance from real-world object imaging, t is run time；Master control borad passes through formula：α=a/ (h_i ²*v_i) determine the undetermined coefficient α of platform specific；Wherein, a is the vibration acceleration of platform structure.

Description

A device and method for monitoring sea ice on an ocean platform

technical field

The invention relates to the monitoring and management of sea ice in the mining of offshore oil platforms in winter. The sea ice monitoring system of the offshore oil platform is established through the platform ice vibration response sensor and the water temperature profile monitor, video monitor and anemometer used for ice condition monitoring to realize the detection of sea ice and ice vibration. And real-time monitoring of ice conditions.

Background technique

With the advancement of technology and the continuous demand for energy, the development of oil and gas in marine resources has been extended to icy sea areas. Offshore oil and gas development and structural design in conventional sea areas only need to consider conventional marine environmental loads (wind, waves, currents), but in icy sea areas, both the design of offshore engineering structures and the drilling and development of resources have to face Problems posed by sea ice.

In most icy sea areas, sea ice poses a far greater threat to marine resource development than waves and wind. There have been many accidents caused by sea ice in history, such as: In 1963, two simple platforms in the Cook Inlet of the United States were overthrown by ice; in 1969, when the Bohai Sea was frozen, my country's "Old No. 2" platform collapsed under the huge thrust of sea ice In the 1970s, the lighthouse in the Gulf of Bosnia collapsed under the action of ice vibration; in the 1980s, the foundation of the Molikpaq caisson in the Beaufort Sea liquefied under the ice-induced vibration. In my country, obvious ice-induced vibrations were also found in many platforms built in the Liaodong Bay of the Bohai Sea in the late 1980s, which caused great safety hazards in the oil and gas development in the Bohai Sea in winter. In the winter of 2000, due to ice-induced vibration, the exhaust pipeline of No. 8 well of a platform in Bohai Sea was fatigued and fractured and the flange was loose, which led to the shutdown of the platform; the continuous ice-induced vibration also had an impact on the operators of the platform, reducing the Comfort and work efficiency, when serious, it will endanger their physical and mental health.

At present, international sea ice management is a system that integrates various means and technologies. Analyze and evaluate the threats posed by sea ice during oil and gas development and ensure production safety.

Since the 1930s, Russia and the Barents Sea have used aircraft observations and icebreaker records to observe icebergs in the Barents Sea for nearly 70 years. Through long-term observation records, we can understand the direction of movement of icebergs in this sea area, the size of icebergs and Distribution of icebergs throughout the ocean. During oil drilling in the Beaufort Sea from 1983 to 1993, in order to avoid being affected by sea ice, a complete sea ice management system was established. Sea ice monitoring and management is an important means to ensure the safe operation of active oil and gas platforms in winter. The implementation of the sea ice management system has effectively protected the drilling facilities during the entire construction process and reduced the threat of sea ice to the entire project.

The existing sea ice disaster prediction technology is mainly aimed at the observation and forecast of sea ice elements, which cannot meet the accuracy and timeliness requirements of sea ice risk early warning for oil and gas platforms. In the field of international cold region engineering development, there is no monitoring and safety management system for oil development in ice regions. Therefore, sea ice monitoring for offshore oil platforms is very necessary to ensure the safe operation of platforms in winter.

Contents of the invention

The purpose of the present invention is to realize sea ice monitoring and management of offshore oil platforms, collect ice vibration data of offshore oil platforms, seawater temperature profile data, sea ice thickness and speed data, and platform area wind speed data. It can provide a basis for sea ice clear forecast, sea ice threat early warning and platform ice vibration failure standard formulation, and at the same time meet the accuracy and timeliness requirements of oil and gas platform sea ice risk early warning.

The invention provides a sea ice monitoring device on an ocean platform, comprising: a main control system composed of a main control machine provided with a main control board, a decoding development board and a host computer, wherein the output end of the decoding development board is connected to the main control board , the output end of the main control board is connected to the upper computer; the video monitor is set on the oil platform to facilitate sea ice monitoring, and its output end is connected to the main control board to transmit the data of sea ice thickness and sea ice speed to the main control board; The response sensor is set at the position of the oil platform workbench, and its output terminal is connected to the decoding development board to transmit the ice-induced vibration data of the offshore oil platform to the decoding development board; the decoding development board sends the decoded data to the main control board; the main control board Process the input monitoring data and transmit it to the host computer; the main control board determines the undetermined coefficient α of the specific platform through the formula: α=a/(h _i ² *v _i ); where a is the vibration acceleration of the platform structure ;The host computer stores and remotely transmits the monitoring data; the video monitor, ice vibration response sensor, main control board, decoding development board and the host computer are all powered by the power supply.

Preferably, the video monitor obtains the thickness of sea ice by the formula: h _i =H_Diameter*T/Dh; wherein, H_Diameter is the aperture of the wave hole whose calibration object is a cone, and T is the pixel size of the ice section on the image, Dh is the anti-wave hole whose calibration object is a cone, the aperture H_Diameter is 20cm, and its pixel size on the image.

Preferably, the video monitor obtains the sea ice speed through the formula: v _i =Hs/(ht); wherein, H is the distance between the lens of the camera and the real object, s is the pixel length on the image, and h is the lens of the camera The imaged distance from the real object, t is the running time.

Preferably, the video monitor transmits the ice angle data to the main control board; the video monitor passes the formula: Obtain the ice orientation angle; where (x ₀ , y ₀ ) is the coordinates of the feature points in the initial frame, and (x ₁ , y ₁ ) is the coordinates of the feature points in the final frame.

Preferably, the monitoring device includes: an anemometer arranged on the top of the oil platform, the output end of which is connected to the main control board, and transmits the wind speed data in the platform area to the main control board.

Preferably, the monitoring device includes: a water temperature profile monitoring sensor installed on the legs of the oil platform extending below the sea level, the output end of which is connected to the main control board, and transmits the temperature profile data at a set depth below the sea level to the main control board ; The clock of the water temperature profile monitoring sensor is: 6:00-18:00; the sampling interval is: 1.5m; the sampling pulse length: 10s.

Preferably, the precision of the ice vibration response sensor is: 10mv/dal.

Preferably, the automatic acquisition time of the video monitor is: 6:00-18:00; the focal length is: 12mm.

The present invention also provides a sea ice monitoring method on an ocean platform, comprising the following steps: Step A. The video monitor obtains the sea ice thickness through the formula: h _i =H_Diameter*T/Dh; The aperture of the wave hole, T is the pixel size of the ice section on the image, Dh is the wave hole whose calibration object is a cone, the aperture H_Diameter is 20cm, and its pixel size on the image; Step B. The video monitor passes the formula: v _i = Hs/(ht) to get the sea ice velocity; where, H is the distance between the camera lens and the real object, s is the pixel length on the image, h is the imaging distance between the camera lens and the real object, and t is the running time ; Step C. The main control board determines the undetermined coefficient α of the specific platform through the formula: α=a/(h _i ² *v _i ); wherein, a is the vibration acceleration of the platform structure.

Preferably, the video monitor adopts the formula: Obtain the ice orientation angle; where (x ₀ , y ₀ ) is the coordinates of the feature points in the initial frame, and (x ₁ , y ₁ ) is the coordinates of the feature points in the final frame.

The present invention has the following effects:

1) According to the device of the present invention, the ice-induced vibration data of the offshore oil platform, the temperature profile data of the set depth below sea level, the sea ice thickness and sea ice speed data, and the wind speed data in the platform area can be collected and processed in a centralized manner, and the monitored data can be stored and remote transmission.

2) The present invention can provide a basis for sea ice and ice clearance forecast, sea ice threat early warning and platform ice vibration failure standard formulation for CNOOC oil platform, and meet the accuracy and timeliness requirements of offshore oil and gas platform sea ice risk early warning.

Description of drawings

Fig. 1 is the on-site installation diagram of the embodiment of the present invention.

Fig. 2 is the principle of image measurement in the embodiment of the present invention.

Fig. 3 is a schematic diagram of ice thickness measurement in platform fixed-point observation according to an embodiment of the present invention.

Fig. 4 shows the change of the position of the target in the embodiment of the present invention.

Fig. 5 Field statistics of the relationship between the maximum acceleration of the platform 1 and the ice speed and ice thickness in the embodiment of the present invention.

Detailed ways

The technical solution of the present invention will be further described in the following selected pairs of embodiments.

1. Invention principle

In the measurement of ice thickness, ice speed and ice direction, the principle of image method measurement is shown in Figure 2. The pixel length of an object with real length L projected onto the image by a camera with focal length f is l. The distance between the lens of the camera and the real object is H, and the distance of the image is h. When H is constant, the ratio of L to l is constant, that is

Therefore, in the application of on-site image measurement, firstly keep the focal length of the camera unchanged, calibrate the camera with an object of known length L, and obtain the ratio n, then the relationship between the length S of the measured object and the pixel length s on the image is:

Then the expression of the true length S of the measured object is obtained as follows.

S=n×s (1-3)

Therefore, in the measurement, the distance H between the object and the lens is constant. However, in actual measurement, the distance H between the measured object and the lens cannot be guaranteed to be exactly the same as the distance during calibration. When the θ angle is very small and the difference of H is small, its influence on the measurement results is small and can basically be ignored. The principle of image measurement is shown in Figure 2.

1.1 Ice thickness measurement

Ice thickness is one of the important factors affecting the form and magnitude of ice loads. The image measurement method is relatively simple, and the image measurement technology has developed rapidly in recent years. If a high-precision camera is used, the small deformation of the structure can be accurately measured, so it is more suitable for on-site ice thickness measurement.

The basic idea of the image method to measure the ice thickness is that after the ice and the structure are broken, the broken ice will turn over and fall into the water, and the section exposed during the turnover can be captured by the camera. The camera is calibrated with an object of known size, and the focal length of the camera is fixed, then the ice thickness can be calculated according to the size of the calibration object and the pixel size of the ice section.

The ice thickness was measured in situ on the jacket platform in Liaodong Bay, Bohai Sea, as shown in Fig. 3. The calibration object is a cone-shaped anti-wave hole, the hole diameter H_Diameter is 20cm, and its pixel size on the image is Dh. The pixel size of the ice section on the image is T, then the actual ice thickness Thickness is expressed as:

Thickness＝20×T/Dh (1-4)

The measured ice thickness is 12.2cm.

1.2. Measurement of ice speed and direction

The principle of ice speed and ice direction measurement is similar to that of ice thickness measurement. Firstly, a relatively fixed ice range is photographed by installing a fixed camera; secondly, the measurement system is calibrated and the calibration coefficient n is calculated; then, the movement trajectory of points with certain characteristics on the ice surface in the video is captured and tracked (such as As shown in Figure 4), through the coordinate changes of the feature points in the initial frame and the final frame, the length s of the pixel point that the feature point moves through is calculated, and then the motion distance of the sea ice is obtained:

S=n×s (1-5)

According to the number of frames before and after, the running time t is obtained, and then the running speed of the ice is obtained:

Assuming that the X-axis direction on the image is 0°, the coordinates of the feature points in the initial frame are (x ₀ , y ₀ ), and the coordinates of the feature points in the final frame are (x ₁ , y ₁ ), then the ice angle is:

2 Platform structure response prediction

The ice vibration response of the platform under the action of sea ice is quite complex, involving many related environmental and structural elements. The study found that the most influential factors on platform ice vibration are sea ice velocity and thickness. Obviously, the thicker the sea ice, the greater the impact on the platform, and the greater the response; similarly, the faster the ice speed, the greater the energy absorbed by the platform when it hits the platform, so the vibration response also increases. For vertical structures, the response of the platform is generally proportional to the ice velocity and ice thickness, but when the tide turns, the platform may vibrate in a steady state, resulting in a maximum response when the ice velocity is small. Therefore, the statistical methods in this section do not include steady-state vibrations of vertical structures.

Based on the actual measurement results of the conical platform in Liaodong Bay, the vibration response amplitude of the platform structure under the action of leveling ice has a linear relationship with the square of the ice thickness and ice velocity, which can be written as:

a=α·h _i ² ·v _i (2-1)

where a is the vibration acceleration of the structure (gal), α is an undetermined coefficient, h _i is the ice thickness (cm), and v _i is the ice velocity (cm/s). Based on the analysis of on-site monitoring data, the undetermined coefficient α of the specific platform can be determined.

3. Example

Take the jacket platform monitoring in a sea area of the Bohai Sea as an example:

According to the sea ice monitoring situation, the ice vibration response sensor, water temperature profile monitoring sensor, video monitor and anemometer are installed on the corresponding positions of the platform (as shown in Figure 1). The main control computer, the decoding development board and the upper computer have been unifiedly designed as the main control system, and a response interface is left outside the system. Connect the data output end of the water temperature profile monitoring sensor, video monitor and anemometer to the reserved interface on the control board of the main control system, and the output end of the ice vibration response sensor to the reserved interface of the main control unit and the decoding development board. The output terminal of the decoding development board is connected to the main control board, and the connection between the output terminal of the main control board and the host computer has been connected in the main control system, and no connection operation is required.

When on-site monitoring work, first set the operating software on the main control machine: set the accuracy of the ice vibration response sensor; automatically collect the time and focal length of the video monitor; set the clock, sampling interval, sampling pulse length, etc. start and end time etc.

After the equipment debugging is completed, the main control system will pre-process, store and remotely transmit the data collected by the ice vibration response sensor, water temperature profile monitoring sensor, video monitor and anemometer. Realize data local storage and remote transmission.

Through the statistics of the measured platform ice vibration acceleration data, it is found that under a certain ice thickness, the platform ice vibration acceleration and ice speed have a certain linear relationship. Using the ice vibration response monitoring data of the platform in winter from 2009 to 2013, the relationship between the ice vibration response, ice thickness and ice velocity of a certain platform is analyzed, as shown in Figure 5.

Based on the above statistical results, using Equation 2-1, the corresponding undetermined coefficient α in the ice vibration acceleration response prediction model of a platform under different ice thickness conditions can be calculated, as shown in Table 1.

Table 1 Corresponding coefficient α under different ice thickness of platform 1

typical ice thickness Correspondence coefficient α 6cm 0.00521 8cm 0.00370 10cm 0.00289 12cm 0.00236

The above embodiments are only used to illustrate the present invention, rather than to limit the present invention. Those of ordinary skill in the relevant technical field can make changes and deformations without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions Also belong to the category of the present invention.

Claims (10)

1. An ocean platform sea ice monitoring device is characterized in that, the monitoring device comprises: A main control system composed of a main control computer with a main control board, a decoding development board and an upper computer is set, wherein the output end of the decoding development board is connected to the main control board, and the output end of the main control board is connected to the upper computer; The video monitor is installed on the oil platform to facilitate sea ice monitoring, and its output terminal is connected to the main control board to transmit the data of sea ice thickness and sea ice speed to the main control board; The ice vibration response sensor is set at the position of the oil platform workbench, and its output terminal is connected to the decoding development board to transmit the ice-induced vibration data of the offshore oil platform to the decoding development board; The decoding development board sends the decoded data to the main control board; the main control board processes the input monitoring data and transmits it to the host computer; The main control board determines the undetermined coefficient α of the specific platform through the formula: α=a/(h _i ² *v _i ); where, a is the vibration acceleration of the platform structure; The host computer stores and remotely transmits the monitoring data; The video monitor, ice vibration response sensor, main control board, decoding development board and host computer are all powered by the power supply. 2. The ocean platform sea ice monitoring device according to claim 1, characterized in that, the video monitor obtains the sea ice thickness by the formula: h _i =H_Diameter*T/Dh; wherein, H_Diameter is a cone for calibration The aperture of the anti-wave hole, T is the pixel size of the ice section on the image, Dh is the anti-wave hole whose calibration object is a cone, the aperture H_Diameter is 20cm, and its pixel size on the image. 3. ocean platform sea ice monitoring device according to claim 1, is characterized in that, described video monitor obtains sea ice speed by formula: v _i =Hs/(ht); Wherein, H is the lens of video camera and real The object distance is, s is the pixel length on the image, h is the imaging distance between the camera lens and the real object, and t is the running time. 4. The ocean platform sea ice monitoring device according to claim 1, wherein the video monitor transmits the ice angle data to the main control board; the video monitor passes the formula: Obtain the ice orientation angle; where (x ₀ , y ₀ ) is the coordinates of the feature points in the initial frame, and (x ₁ , y ₁ ) is the coordinates of the feature points in the final frame. 5. According to the marine platform sea ice monitoring device described in any one of claims 1 to 4, it is characterized in that the monitoring device includes: an anemometer arranged on the top of the oil platform, its output end is connected with the main control board, And transmit the wind speed data in the platform area to the main control board. 6. The ocean platform sea ice monitoring device according to any one of claims 1 to 4, characterized in that, the monitoring device comprises: a water temperature profile monitoring sensor arranged on the legs of the oil platform extending below the sea level, wherein The output end is connected with the main control board, and the temperature profile data of the set depth below sea level is transmitted to the main control board; the clock of the water temperature profile monitoring sensor is: 6:00-18:00; the sampling interval is: 1.5m; Pulse length: 10s. 7. The sea ice monitoring device for an ocean platform according to claim 1, wherein the accuracy of the ice vibration response sensor is: 10mv/dal. 8. The sea ice monitoring device on the ocean platform according to claim 1, wherein the automatic collection time of the video monitor is: 6:00-18:00; the focal length is: 12mm. 9. A method for monitoring sea ice on an ocean platform, comprising the following steps: Step A. The video monitor obtains the sea ice thickness through the formula: h _i =H_Diameter*T/Dh; wherein, H_Diameter is the aperture of the wave hole whose calibration object is a cone, T is the pixel size of the ice section on the image, and Dh is The calibration object is the anti-wave hole of the cone, the aperture H_Diameter is 20cm, and its pixel size on the image; Step B. The video monitor obtains the sea ice velocity by the formula: v _i =Hs/(ht); wherein, H is the distance between the lens of the camera and the real object, s is the pixel length on the image, and h is the lens of the camera and the real object The distance imaged by the object, t is the running time; Step C. The main control board determines the undetermined coefficient α of the specific platform through the formula: α=a/(h _i ² *v _i ); wherein, a is the vibration acceleration of the platform structure. 10. ocean platform sea ice monitoring method according to claim 9, is characterized in that, described video monitor is by formula: Obtain the ice orientation angle; where (x ₀ , y ₀ ) is the coordinates of the feature points in the initial frame, and (x ₁ , y ₁ ) is the coordinates of the feature points in the final frame.