A system and method for observing the vertical profile of seabed temperature in a shallow sea area

Abstract

The present application is a kind of shallow sea seabed mud temperature vertical section observation system and method, related to mud temperature observation technical field, on the deck of oceanographic research vessel, mud temperature observation system is assembled, mud temperature observation system is slowly lowered by crane, PVC stick assembly first contacts seabed mud, high pressure water flushing device is started, high pressure water impacts seabed mud, continue to slowly lower, underwater camera monitors the whole process, mud temperature column slowly presses into seabed mud, after completing deployment, mud temperature column measures the temperature of mud at different depths, realizes long-term measurement of seabed mud temperature vertical section.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mud temperature observation, in particular to a system and method for observing vertical profile of mud temperature in shallow sea area. BACKGROUND

[0002] Heat exchange between sea and air has been studied for a long time, and a large amount of long-term continuous observation data has been obtained, and a relatively mature parameterization model has been established. However, the heat exchange between seawater and seabed mud is less studied, and the long-term continuous seawater and seabed mud temperature synchronous observation is also less, and the observation data in this aspect is urgently needed. Especially in the continental shelf shallow sea area, the seawater temperature changes greatly with the season, and the temperature of the whole layer of seawater changes, that is, the seawater temperature directly contacting the seabed mud also changes dramatically, which will inevitably cause the heat exchange between seawater and seabed mud that cannot be ignored.

[0003] Seabed mud temperature is an important seabed geophysical parameter, which has important significance for studying marine corrosion. At the same time, it is a physical parameter that must be considered in marine engineering such as external heating of seabed oil transportation pipeline, initial temperature setting of oil transportation, service life evaluation of oil transportation pipeline, exploration and exploitation of marine oil and natural gas, etc.

[0004] However, in terms of marine mud temperature measurement, there is less in-situ measurement data, less long-term observation data (monthly or weekly), and basically no annual cycle mud temperature observation data, which leads to the fact that the existing research on seabed mud temperature is shallow. Therefore, it is urgent to carry out annual cycle seabed mud temperature observation.

[0005] Most of the offshore waters in China are shallow, and the seabed mud is mostly sandy soil, which is relatively soft. Compared with other materials, it is relatively easy to insert the mud temperature measuring device into the seabed mud to a certain depth to complete the measurement of the mud temperature.

[0006] In the measurement of seabed mud temperature, most of the past uses stainless steel material to fix the mud temperature measuring equipment in or outside the stainless steel pipe to complete the measurement of the mud temperature. Steel material has good thermal conductivity, which will inevitably cause heat transfer during the measurement process, thereby affecting the measurement of the mud temperature, and the mud temperature measurement is not accurate, especially in long-term observation of mud temperature. In order to improve the accuracy of mud temperature measurement, it is necessary to select materials with low thermal conductivity or low thermal conductivity to replace stainless steel materials for mud temperature measurement, especially in long-term mud temperature observation. SUMMARY

[0007] To solve the above problems, the present application provides a system for observing vertical profile of mud temperature in shallow sea area, which comprises: a mud temperature column, a high-pressure water flushing device, a real-time display terminal, and an underwater camera.

[0008] The mud temperature column comprises a PVC rod assembly and a self-contained mud temperature instrument; the PVC rod assembly contacts the seabed mud, and the self-contained mud temperature instrument is placed at different positions of the PVC rod assembly to measure the temperature of the seabed mud at different depths, thereby achieving long-term measurement of the vertical profile of the seabed mud.

[0009] The underwater camera vertically monitors the mud temperature column and transmits real-time images to the real-time display terminal.

[0010] The high-pressure water flushing device is used to form high-pressure water flushing from the bottom end of the mud temperature column to impact the seabed mud.

[0011] In the preferred embodiment, the PVC rod assembly comprises a PVC rod, a stainless steel clamping belt, and a stainless steel clamping ring.

[0012] The PVC rod is bonded with the stainless steel pipe of the mud temperature column, and the stainless steel clamping ring clamping groove, the self-contained mud temperature instrument clamping groove, the flow guide groove, and the stainless steel clamping belt clamping groove are formed on the PVC rod.

[0013] The self-contained mud temperature instrument clamping groove is used to place the self-contained mud temperature instrument, the stainless steel clamping belt clamping groove is used to fix the stainless steel clamping belt, the stainless steel clamping ring clamping groove is used to fix the stainless steel clamping ring, and the flow guide groove is used to guide the seawater for high-pressure impact on the seabed mud.

[0014] In the preferred embodiment, the PVC rod is provided with seven self-contained mud temperature instrument clamping grooves, and the probes of the self-contained mud temperature instruments are respectively located at the self-contained mud temperature instrument clamping grooves at 0.0 m, 0.5 m, 1.0 m, 1.5 m, 2.0 m, 2.5 m, and 3.0 m.

[0015] In the preferred embodiment, the observation system further comprises a first heavy block and a second heavy block, the stainless steel clamping ring is fastened on the mud temperature column by bolts and connected with the first heavy block by a plurality of U-shaped buckles; the second heavy block is connected with the first heavy block by a plurality of anchor chains, the plurality of U-shaped buckles are connected by a release buckle, and the second heavy block has a lifting point connected with the plurality of anchor chains by a release buckle.

[0016] In the preferred embodiment, the high-pressure water flushing device comprises a high-pressure water pump, a water inlet pipe, and a high-pressure water pipe; one end of the high-pressure water pump is connected with the water inlet pipe, the other end is connected with the high-pressure water pipe, and the high-pressure water pipe is connected with the stainless steel pipe in the middle of the mud temperature column; the seawater is introduced into the stainless steel pipe in the middle of the mud temperature column through the high-pressure water pipe to form high-pressure water flushing from the bottom end of the mud temperature column to impact the seabed mud.

[0017] In the preferred embodiment, the PVC rod has a diameter of 12 cm and a length of 340 cm, and the lower end is conical.

[0018] In the preferred embodiment, the self-contained mud temperature instrument is powered by a lithium battery, the sampling interval is 10 s, and the temperature measurement range is -5℃ to 45℃.

[0019] The application further provides a method for observing a vertical section of seabed mud temperature in a shallow sea area, which is realized by the observation system and comprises the following steps: assembling the mud temperature observation system on a deck of a marine survey ship; slowly lowering the mud temperature observation system by a crane, wherein the PVC rod assembly first contacts seabed mud, the high-pressure water flushing device is started, high-pressure water impacts the seabed mud, and the mud temperature column is slowly pressed into the seabed mud, and the whole process is monitored by the underwater camera; and after the deployment is completed, the mud temperature column measures the temperature of the seabed mud at different depths by the self-contained mud temperature instrument at different positions, so that long-term measurement of the vertical section of seabed mud temperature is realized.

[0020] The PVC rod made of polyvinyl chloride material with good heat insulation performance is used as a carrier for mud temperature profile measurement, and has the following advantages.

[0021] First, the PVC rod has good heat insulation, and the thermal conductivity of the PVC rod is 0.16 W / (m·K); in marine observation, in order to reduce the corrosion of seawater on steel as much as possible, stainless steel is generally used, and the thermal conductivity of stainless steel is about 16-19 W / (m·K), which is 100 times different from that of the PVC rod; in the ocean, the types of seabed mud are different, and the thermal conductivity of the seabed mud is also different, which is about 1.0 W / (m·K); the thermal conductivity of seawater is 0.6-0.7 W / (m·K); from the above analysis, it can be seen that the thermal conductivity of the PVC rod is very low, so the use of the PVC rod material can greatly reduce the heat conduction caused by the mud temperature measurement device, and further reduce the measurement error.

[0022] Second, the PVC rod has stable physical and chemical properties, good salt resistance, and will not deform, become brittle, or be corroded when immersed in seabed mud; the density of the PVC rod is about 1.4 g / cm 3 , the density of seawater is about 1.03 g / cm 3 , and the density of the PVC rod is greater than that of seawater.

[0023] Third, the PVC rod is cheap, easy to process, and widely used in the market.

[0024] Fourth, due to the good heat insulation and easy processing of the PVC rod, the temperature measurement can be embedded in the PVC rod, which can reduce the resistance of the PVC rod inserted into the seabed mud and facilitate the operation at sea.

[0025] Compared with the prior art, the application has the following beneficial technical effects:

[0026] The PVC rod is used as an observation platform, which can greatly reduce the influence of heat conduction of the observation platform on mud temperature measurement and improve the accuracy of mud temperature measurement.

[0027] The PVC rod is embedded with a stainless steel pipe in the middle, which increases the strength of the whole mud temperature column, provides space for the installation of the self-contained mud temperature instrument, and makes the whole mud temperature column smooth and easy to insert into the sea mud.

[0028] The high-pressure water jet can easily insert the mud temperature column into the sea mud, and the strength of the high-pressure water jet can be adjusted to adapt to different sea mud. The strength of the high-pressure water jet can also be adjusted to enable the mud temperature column to be pressed into a deeper depth, thereby increasing the length of the mud temperature column to measure a deeper mud temperature vertical profile. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The figure is a schematic diagram of the overall structure of the observation method of the present application.

[0030] Figure 2 The figure is a schematic diagram of the overall structure of the observation method of the present application.

[0031] Figure 3 The figure is a schematic diagram of the overall structure of the observation method of the present application.

[0032] Figure 4 The figure is a schematic diagram of the overall structure of the observation method of the present application.

[0033] Figure 5 The figure is a schematic diagram of the overall structure of the observation method of the present application. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0035] Embodiment 1

[0036] As shown in the figure, it is a schematic diagram of the overall structure of the observation system of the vertical profile of the sea bottom mud temperature in the shallow sea area. Figure 1

[0037] The oceanographic research vessel provides a support platform for the deployment and recovery of the mud temperature column.

[0038] One end of the high-pressure water pump is connected to the water inlet pipe, and the other end is connected to the high-pressure water pipe, which is further connected to the stainless steel pipe in the middle of the mud temperature column, forming a set of high-pressure water flushing device.

[0039] The stainless steel ring is fastened to the mud temperature column by bolts and connected to the first heavy block 1 by four U-shaped buckles. The second heavy block 2 is connected to the first heavy block 1 by four anchor chains with a specification of 8 mm, i.e. connected to the four U-shaped buckles by unfastening the buckles, and the second heavy block 2 has a lifting point connected to the four anchor chains by unfastening the buckles.​

[0040] The hoisting cable of the oceanographic survey ship is connected with 4 short steel cables, which are connected with the 4 hoisting points of the first weight 1 by shackles, so that the whole observation system can be hoisted.

[0041] The camera end of the underwater camera is fixed on the hoisting cable, which monitors the mud temperature column vertically downward, and the real-time picture is transmitted to the real-time display terminal of the oceanographic survey ship.

[0042] The high-pressure water pump is used to extract seawater to generate high-pressure water, which is introduced into the steel pipe in the middle of the mud temperature column through the high-pressure water pipe, forming high-pressure water at the bottom end of the mud temperature column, impacting the seabed mud, making the seabed mud soft, and under the pressure of the first weight 1, the mud temperature column can slowly descend, as the depth of the mud temperature column inserted into the mud increases, seawater flows out along the guide groove on the side of the mud temperature column, and can carry the mud out, the mud temperature column can continue to descend, until the mud temperature column is completely inserted into the mud, completing the deployment.

[0043] It should be noted that the process of using the high-pressure water pump to extract seawater to generate high-pressure water is as follows: using a variable frequency motor to provide power, accurately controlling the water pressure by adjusting the frequency of the variable frequency motor. During the process of impacting the mud, start from low water pressure, gradually increase the frequency of the variable frequency motor according to the situation of impacting the mud, obtain appropriate water pressure, stop adjusting the motor frequency, and start slowly pressing the mud temperature column.

[0044] The underwater camera monitors the state of the mud temperature column, helps to control the lowering speed when the mud temperature column is lowered on the hoisting cable, ensures that the mud temperature column cannot be tilted, and monitors the depth of the lowering in real time, stops the lowering when the whole mud temperature column is pressed into the mud, and stops the high-pressure water.

[0045] The stainless steel clasp is fixed in the clamping groove reserved in the mud temperature column, tightly fixed on the mud temperature column, which can slowly press the mud temperature column into the mud under the pressure of the first weight 1 during deployment, keep the mud temperature column in place during observation, and slowly pull out the whole mud temperature column from the mud when the observation is completed.

[0046] The second weight 2 falls to the seabed first during deployment, contacts the mud after falling to the seabed, does not move the position, can keep the mud temperature column from swinging when pressing the mud temperature column, does not move in the fixed position even under the impact of high-pressure water, and ensures that the mud temperature column is vertically pressed into the mud.

[0047] The mud temperature column is the key part of the whole mud temperature observation method, as shown in Figure 2 The mud temperature column includes three parts: PVC rod assembly, stainless steel pipe, and self-contained mud temperature instrument.

[0048] (1) PVC rod assembly

[0049] The PVC rod assembly comprises a PVC rod, a stainless steel clamping belt and a stainless steel clamping ring.

[0050] First, a whole PVC rod is made, and in the process of making, a stainless steel pipe is pre-buried therein. After the PVC material is cooled, the PVC rod and the stainless steel pipe are bonded together to form a whole. Then, grooves are opened on the PVC rod, including a stainless steel clamping ring clamping groove, a self-contained mud temperature instrument clamping groove (on two opposite sides of the PVC rod), a flow guide groove and a stainless steel clamping belt clamping groove. The self-contained mud temperature instrument is placed in the self-contained mud temperature instrument clamping groove, and the stainless steel clamping belt is used to fix the position of the stainless steel clamping belt clamping groove. The lower end of the PVC rod is processed into a conical shape. Two flow guide grooves are opened on the other two opposite sides of the PVC rod.

[0051] PVC is the abbreviation of polyvinyl chloride, which has good thermal insulation and strong hardness and can meet the requirements of sea mud temperature observation in a mud bottom sea area.

[0052] A PVC rod with a diameter of 12 cm and a length of 340 cm is selected. The lower end of the PVC rod is processed into a conical shape to reduce the resistance when pressing down. The upper end of the PVC rod is left with a stainless steel clamping ring clamping groove to fix the stainless steel clamping ring, so that the stainless steel clamping ring and the PVC rod are more firmly fixed together.

[0053] Grooves are opened on the side of the PVC rod, and a self-contained mud temperature instrument clamping groove with a depth of 3.0 cm and a length of 30 cm is formed. The self-contained mud temperature measuring instrument probe can be fixed in the PVC rod, and a stainless steel clamping belt clamping groove is opened to make the stainless steel clamping belt fall into the clamping groove, so that the self-contained mud temperature instrument can be more firmly fixed.

[0054] Seven self-contained mud temperature instrument clamping grooves are arranged on the PVC rod, and the probes of the self-contained mud temperature instruments are respectively located at 0.0 m, 0.5 m, 1.0 m, 1.5 m, 2.0 m, 2.5 m and 3.0 m. The number of layers can also be set according to the engineering requirements. Grooves are opened on the side of the PVC rod, which will inevitably affect the firmness of the PVC rod. In order to reduce the impact of the grooves on the strength of the PVC rod as much as possible, grooves are opened on the symmetrical two sides of the PVC rod. In addition to the groove for placing the self-contained mud temperature instrument, flow guide grooves are also left on the other two sides of the PVC rod to guide the seawater for high-pressure impact on the sea mud. The probe part of the self-contained mud temperature instrument is partially open to fully contact with the sea mud.

[0055] (2) Stainless steel pipe

[0056] A stainless steel pipe with a diameter of 4cm and a wall thickness of 0.5cm is pre-embedded in the middle of the PVC rod. This serves two purposes: first, it enhances the overall strength of the PVC rod, making it less prone to breakage; second, it allows for high-pressure water jetting to soften the marine mud and carry it away with the water flow, making it easier to press the mud-temperature column into the mud. A textured finish is machined onto the upper end of the stainless steel pipe. After the mud-temperature column is deployed, the top of the stainless steel pipe is sealed to prevent the seawater and marine mud from flowing up and down.

[0057] (3) Self-contained mud temperature gauge

[0058] The self-contained mud temperature meter, preferably rated T, measures mud temperature. It is a self-contained temperature measurement device powered by a lithium battery with automatic data storage, resulting in extremely low power consumption. Using a 10-second sampling interval, its power and storage capacity are sufficient for year-round observations. The temperature measurement accuracy is 0.002℃, and the temperature measurement range is -5℃ to 45℃. The mud temperature meter is 30cm long and 2.54cm in diameter.

[0059] A schematic diagram of the mud-temperature column after it has been placed on the seabed is shown below. Figure 3 As shown, the mud temperature column is vertically inserted into the sea mud to a depth of approximately 3.1m. A second weight 2 rests on the seabed interface, and a stainless steel retaining ring rests on and is fixed to the second weight 2. Sea mud is filled into a stainless steel pipe, which is then sealed with a stainless steel pipe cap to prevent the mud from flowing inside. This mud temperature column can be deployed on the seabed long-term, capable of measuring sea mud temperatures at depths of 0.0m, 0.5m, 1.0m, 1.5m, 2.0m, 2.5m, and 3.0m, completing long-term vertical profile measurements of seabed mud temperature.

[0060] The second weight is made of lead, which has a high density of 11.3 g / cm³. 3 It is more than 10 times denser than seawater and is used to stabilize the mud temperature column and place it on the seabed. It is made of lead material and is a ring-shaped lead disc weighing 100 kg each. The diameter of the inner ring is larger than the diameter of the mud temperature column, leaving space. There are also 4 holes in the ring-shaped lead disc, so that the seawater on the seabed can fully contact the seabed mud, without affecting the mud temperature on the surface of the seabed mud, and ensuring the accuracy of mud temperature measurement.

[0061] The stainless steel retaining ring consists of two halves, tightly bolted to the mud thermopile, becoming an integral part of it. This facilitates the hoisting of the mud thermopile during deployment and simultaneously withstands the pressure of the first weight block 1, allowing the mud thermopile to be slowly pressed into the seabed mud. During retrieval, the stainless steel retaining ring can be directly hoisted to lift the entire mud thermopile. The stainless steel retaining ring does not interfere with the contact between the seawater and the seabed mud.

[0062] Example 2

[0063] The operation process of the offshore field observation is as follows: (1) the ocean survey ship reaches the observation sea area, and the ship is anchored by front and rear anchors, and the position of the ship cannot be moved during the whole laying process of the mud temperature observation system;

[0064] (2) the ocean survey ship is equipped with a crane, the lifting force of the crane is more than 500 kg, the crane arm can lift an object 4 meters high, and can be placed outside the ship body.

[0065] (3) on the deck of the ocean survey ship, the mud temperature observation system is assembled, the whole device is lifted by the crane and placed outside the ship body, and then slowly lowered, the PVC rod assembly first contacts the sea mud on the seabed, then the high-pressure water flushing device is started, the high-pressure water impacts the seabed mud, at the same time, the slow lowering continues, and the mud temperature column slowly presses into the seabed mud. During the lowering process, the underwater camera monitors the whole process to ensure the successful completion of the laying process. Then the diver dives, unfastens the connection between the first weight 1 and the stainless steel ring, recovers the first weight 1 to the deck, connects the second weight 2 with the stainless steel ring, and the whole laying work is completed.

[0066] The field observation data in the sea area are obtained by using the observation method in a specific sea area for a month of mud temperature vertical profile observation from November 22, 2023 to December 22, 2023, and the mud temperature data at depths of 0.0 m, 0.5 m, 1.0 m, 0.5 m, 2.0 m, 2.5 m and 3.0 m are obtained, and the observation data are shown in Figure 5

[0067] It is apparent to those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, but can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the embodiments should be considered as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended to encompass all changes falling within the meaning and scope of the equivalent elements of the claims. Any reference signs in the claims should not be considered as limiting the claims involved.​

Claims

1. A system for observing the vertical profile of bottom sediment temperature in a shallow sea area, characterized by comprising: The application relates to a mud temperature observation system. The mud temperature column comprises a PVC rod assembly and self-contained mud temperature instruments; the PVC rod assembly contacts sea mud on the seabed, and the self-contained mud temperature instruments are arranged at different positions of the PVC rod assembly and used for measuring the sea mud temperature at different depths to realize long-term measurement of the vertical profile of the sea mud on the seabed. The underwater camera vertically monitors the mud temperature column and transmits real-time pictures to the real-time display terminal; the high-pressure water flushing device is used for forming high-pressure water flushing from the bottom end of the mud temperature column to impact the sea mud on the seabed. The PVC rod assembly comprises a PVC rod, a stainless steel clamping belt and a stainless steel clamping ring. The PVC rod and the stainless steel pipe of the mud temperature column are bonded, the stainless steel pipe is arranged at the middle position of the PVC rod, the upper end of the stainless steel pipe is provided with a thread, and the top end of the stainless steel pipe is blocked after the mud temperature column is arranged. The PVC rod is provided with seven self-contained mud temperature instrument clamping grooves, so that the probes of the self-contained mud temperature instruments are respectively arranged at the self-contained mud temperature instrument clamping grooves at 0.0 m, 0.5 m, 1.0 m, 1.5 m, 2.0 m, 2.5 m and 3.0 m. The self-contained mud temperature instrument clamping groove is used for placing the self-contained mud temperature instrument, the stainless steel clamping belt clamping groove is used for fixing the stainless steel clamping belt, the stainless steel clamping ring clamping groove is used for fixing the stainless steel clamping ring, and the flow guide groove is used for guiding the sea water for high-pressure impact on the sea mud. The stainless steel clamping ring is fastened on the mud temperature column by bolts and connected with the first heavy block by a plurality of U-shaped buckles; the second heavy block is connected with the first heavy block by a plurality of anchor chains, the plurality of U-shaped buckles are connected by a release buckle, and the second heavy block is provided with a lifting point and connected with the plurality of anchor chains by a release buckle. The high-pressure water flushing device comprises a high-pressure water pump, a water inlet pipe and a high-pressure water pipe; one end of the high-pressure water pump is connected with the water inlet pipe, the other end is connected with the high-pressure water pipe, and the high-pressure water pipe is connected with the stainless steel pipe at the middle position of the mud temperature column. The PVC rod has a diameter of 12 cm and a length of 340 cm, and the lower end is conical. The self-contained mud temperature instrument is powered by a lithium battery, the sampling interval is 10 s, and the temperature measurement range is-5 DEG C to 45 DEG C. On the deck of the oceanographic survey ship, the mud temperature observation system is assembled, the mud temperature observation system is slowly lowered by a crane, the PVC rod assembly first contacts the sea mud on the seabed, the high-pressure water flushing device is started, the high-pressure water impacts the sea mud on the seabed, and the process is continuously slowly lowered, the underwater camera monitors the whole process, the mud temperature column is slowly pressed into the sea mud on the seabed, the mud temperature at different depths is measured by the self-contained mud temperature instruments at different positions after the arrangement is completed, and long-term measurement of the vertical profile of the mud temperature on the seabed is realized.

2. A method for observing a vertical profile of seabed sediment temperature in a shallow sea area, which is realized by the observation system according to claim 1, characterized in that: ​

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