Submarine natural gas hydrate in-situ measurement method and measurement equipment

Abstract

The invention discloses a submarine natural gas hydrate in-situ measurement method and measurement equipment. The method comprises the steps that S1, a wire-line coring drilling tool is put into a well; s2, coring drilling is conducted through a wire-line coring drilling tool, and drilling is stopped when a rock core is filled with a rock core barrel; s3, the inner pipe assembly is taken out through a rope fishing assembly; s4, lifting the drill for the first time; s5, putting the Raman spectrometer into the outer pipe assembly by adopting a rope fisher; s6, the drill is lifted for the second time, and the probe is adopted to detect whether ice-like crystals exist or not; s7, if the Raman spectrometer is not detected, the Raman spectrometer is taken out, the inner tube assembly is put into the Raman spectrometer, and the steps S2-S6 are repeated; s8, if the natural gas hydrate reservoir is detected, positioning the position of the potential natural gas hydrate reservoir, carrying out laser Raman scanning through a probe, analyzing and judging whether the natural gas hydrate exists or not, then taking out the Raman spectrometer, putting the Raman spectrometer into the inner pipe assembly, and repeating the steps S2-S6; in this way, drilling coring, camera shooting observation and in-situ Raman spectrum measurement can be achieved at the same time, and the exploration efficiency and accuracy are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of seabed natural gas hydrate exploration, and in particular to a seabed natural gas hydrate in-situ measurement method and measurement equipment. Background Art

[0002] Natural gas hydrate is a new type of unconventional energy with the advantages of no pollution, high energy density, wide distribution and large reserves. Accelerating the development and utilization of natural gas and promoting its coordinated and stable development are of great significance to environmental protection and energy development. The seabed is one of the main areas where natural gas hydrates are found. Therefore, how to efficiently and accurately explore it has become an urgent problem to be solved.

[0003] At present, the main methods for marine hydrate exploration include heat preservation and pressure maintenance drilling sampling and other technologies. However, the heat preservation and pressure maintenance drilling sampling drill tool structure is complex, the number of coring times is high, the drilling cost is high, and the hydrate in the sample is very easy to decompose, affecting the measurement accuracy; at the same time, during the logging process, real-time measurement is usually not possible. As time goes by, the hydrate is prone to endothermic decomposition, which affects the reliability of logging, resulting in insufficient fine characterization of the reservoir, which in turn affects the subsequent reservoir exploitation. Summary of the invention

[0004] The main purpose of the present invention is to provide an in-situ measurement method and measurement equipment for seabed natural gas hydrate, aiming to solve the above problems.

[0005] To achieve the above object, the present invention provides an in-situ measurement method for seabed natural gas hydrate, comprising the following steps:

[0006] Step S1, putting the rope coring drill into the well;

[0007] Step S2, using the rope coring drill to perform coring drilling on the target formation, and stopping drilling when the core tube in the rope coring drill is full of core;

[0008] Step S3, using the rope salvage assembly of the rope coring drill to remove the inner tube assembly in the rope coring drill from the outer tube assembly of the rope coring drill, and removing the core tube in the inner tube assembly to preserve the core;

[0009] Step S4, lifting the drill once and washing the hole with drilling fluid;

[0010] Step S5, using a rope salvage device to put the Raman spectrometer into the outer tube assembly until the probe of the Raman spectrometer extends out from the drill bit of the rope coring drill;

[0011] Step S6, lifting the drill for a second time, and using the probe to detect whether there are ice-like crystals in the target formation;

[0012] Step S7, if the probe does not detect the ice-like crystals, the Raman spectrometer is taken out from the outer tube assembly by using the rope salvage device, and the inner tube assembly is put into the outer tube assembly by using the rope salvage assembly, and steps S2-S6 are repeated;

[0013] Step S8: If the probe detects the ice-like crystals, the potential natural gas hydrate reservoir is located, and laser Raman scanning is performed by the probe to analyze and determine whether natural gas hydrates exist in the target formation, and then the Raman spectrometer is taken out from the outer tube assembly by using the rope salvage assembly, and the inner tube assembly is put into the outer tube assembly by using the rope salvage assembly, and steps S2-S6 are repeated.

[0014] Furthermore, the probe includes a visible light source, a camera, a Raman laser light source and a detector;

[0015] The step S6 specifically includes:

[0016] The visible light source is turned on, the drill is lifted a second time, and the camera is used to observe whether ice-like crystals exist in the target stratum.

[0017] Furthermore, the step S8 specifically includes:

[0018] Step S81: if the ice-like crystals are observed by the camera, the potential natural gas hydrate reservoir is located according to the position of the drill bit;

[0019] Step S82, turning off the visible light source, and turning on the Raman laser light source and the detector, performing laser Raman scanning corresponding to the potential natural gas hydrate reservoir position, and transmitting the scanning result to the control terminal for analysis and determination of whether there is natural gas hydrate in the target formation;

[0020] Step S83: After the laser Raman scan is completed, turn off the Raman laser light source and the detector, use the rope salvage device to take out the Raman spectrometer from the outer tube assembly, and use the rope salvage assembly to put the inner tube assembly into the outer tube assembly, and repeat steps S2-S6.

[0021] Furthermore, the step S82 specifically includes:

[0022] Step S821, turning off the visible light source, and turning on the Raman laser light source and the detector, performing laser Raman scanning corresponding to the potential natural gas hydrate reservoir position, and transmitting the scanning result to the control terminal for analysis to obtain a Raman spectrum curve;

[0023] Step S822, judging whether there is natural gas hydrate in the target formation according to the Raman spectrum curve;

[0024] Step S823: If natural gas hydrate exists in the target formation, the occurrence state and density characteristics of the natural gas hydrate are analyzed according to the Raman spectrum curve.

[0025] Furthermore, the step S822 specifically includes:

[0026] Whether there is natural gas hydrate in the target formation is determined according to the characteristic peak of the Raman spectrum curve.

[0027] Furthermore, the step S823 specifically includes:

[0028] If natural gas hydrate exists in the target formation, the structural composition, temperature and pressure conditions and density of the natural gas hydrate are obtained according to the height and area of ​​the characteristic peak of the Raman spectrum curve.

[0029] Furthermore, when the drill is lifted once, the active height of the drill bit is set to L1, the length of the probe is set to L2, and L1≥2L2.

[0030] Furthermore, the drilling fluid includes plant gum.

[0031] The present invention also provides an in-situ measurement device for seabed natural gas hydrates, which is applicable to the in-situ measurement method for seabed natural gas hydrates. The in-situ measurement device for seabed natural gas hydrates comprises:

[0032] A rope coring drill, comprising an inner tube assembly, an outer tube assembly, a drill bit and a rope salvage assembly, wherein the rope salvage assembly and the inner tube assembly are movably arranged in the outer tube assembly, the drill bit is arranged at the bottom end of the outer tube assembly, and the inner tube assembly comprises a core tube;

[0033] A Raman spectrometer, detachably mounted on the outer tube assembly, comprising a probe, the probe being used to extend through the outer tube assembly and out of the drill bit to perform Raman spectrum detection;

[0034] a rope catching device for placing or removing the Raman spectrometer from the outer tube assembly; and

[0035] A control terminal is electrically connected to the Raman spectrometer.

[0036] Furthermore, the probe includes a visible light source, a camera, a Raman laser light source and a detector; and / or,

[0037] The Raman spectrometer further comprises a connecting tube, which is extended in the up-down direction, and the probe is connected to the rope salvage device through the connecting tube.

[0038] In the technical solution of the present invention, the rope coring drill and the Raman spectrometer matched therewith are used to detect seabed natural gas hydrates, which can simultaneously realize the drilling and coring of seabed hydrate-containing formations, video observation and in-situ Raman spectrum measurement, real-time determination of the Raman spectrum of the hydrate reservoir under in-situ temperature and pressure conditions, determination of the occurrence state and density characteristics of the hydrate reservoir, and effectively increase the efficiency and accuracy of geological exploration of hydrate-containing formations. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0040] Figure 1 A flow chart of the in-situ measurement method of seabed natural gas hydrate provided by the present invention;

[0041] Figure 2 for Figure 1 Flow chart of step S8;

[0042] Figure 3 for Figure 2 Flow chart of step S82;

[0043] Figure 4 A schematic diagram of the structure of the in-situ measurement device for seabed natural gas hydrate provided by the present invention (when the Raman spectrometer is placed in a rope coring drill);

[0044] Figure 5 It is a schematic diagram of the structure of a rope coring drill;

[0045] Figure 6 for Figure 4 Schematic diagram of part of the structure of the in-situ measurement equipment for natural gas hydrates on the seabed.

[0046] Description of Figure Numbers:

[0047]

[0048] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0051] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme that satisfies both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0052] Natural gas hydrate is a new type of unconventional energy with the advantages of no pollution, high energy density, wide distribution and large reserves. Accelerating the development and utilization of natural gas and promoting its coordinated and stable development are of great significance to environmental protection and energy development. The seabed is one of the main areas where natural gas hydrates are found. Therefore, how to efficiently and accurately explore it has become an urgent problem to be solved.

[0053] At present, the main methods for marine hydrate exploration include heat preservation and pressure maintenance drilling sampling and other technologies. However, the heat preservation and pressure maintenance drilling sampling drill tool structure is complex, the number of coring times is high, the drilling cost is high, and the hydrate in the sample is very easy to decompose, affecting the measurement accuracy; at the same time, during the logging process, real-time measurement is usually not possible. As time goes by, the hydrate is prone to endothermic decomposition, which affects the reliability of logging, resulting in insufficient fine characterization of the reservoir, which in turn affects the subsequent reservoir exploitation.

[0054] In view of this, the present invention provides an in-situ measurement method for seabed natural gas hydrate. Figures 1 to 3 A flow chart of the in-situ measurement method of seabed natural gas hydrate provided by the present invention.

[0055] See also Figure 1 The in-situ measurement method of seabed natural gas hydrate comprises the following steps:

[0056] Step S1, putting the rope coring drill into the well.

[0057] It should be noted that in the present invention, the rope coring drill tool adopts the existing conventional rope coring drill tool, including an inner tube assembly, an outer tube assembly, a drill bit and a rope salvage assembly. The rope salvage assembly and the inner tube assembly are movably arranged in the outer tube assembly, the drill bit is arranged at the bottom end of the outer tube assembly, and the inner tube assembly includes a core tube.

[0058] Step S2: Use the rope coring drill to perform coring drilling on the target formation, and stop drilling when the core tube in the rope coring drill is full of core.

[0059] Step S3: using the rope salvage assembly of the rope coring drill to remove the inner tube assembly in the rope coring drill from the outer tube assembly of the rope coring drill, and removing the core tube in the inner tube assembly to preserve the core.

[0060] In this step, the inner tube assembly is taken out from the outer tube assembly, which can not only take out the core for storage, but also provide space for the Raman spectrometer to be put into the subsequent step S5 for detection; and the rope coring drill is not taken out as a whole, which saves the time of lifting the drill and improves the detection efficiency.

[0061] Step S4, lift the drill once and use drilling fluid to wash the hole.

[0062] In this step, a salvage mechanism is used to lift the drill once, and when the drill is lifted once, the active height of the drill bit is set to L1, the length of the probe is set to L2, and L1≥2L2, so as to leave sufficient space between the drill bit and the bottom of the hole to facilitate the implementation of the subsequent step S5, that is, to provide sufficient space to place the probe of the Raman spectrometer for detection.

[0063] In addition, in the present invention, a drilling fluid with a relatively low temperature and good transparency is used for hole washing. Furthermore, in one embodiment of the present invention, the drilling fluid includes plant gum.

[0064] Step S5: Use a rope salvage device to lower the Raman spectrometer into the outer tube assembly until the probe of the Raman spectrometer extends out of the drill bit of the rope coring drill (e.g. Figure 4 shown).

[0065] In this step, there is no need to remove the rope coring drill as a whole. Instead, only the inner tube assembly is removed to provide a placement space for the Raman spectrometer. The Raman spectrometer is then used to perform real-time and continuous analysis of seabed natural gas hydrates in situ to determine information such as the structure and composition, temperature and pressure conditions, density, and decomposition and secondary synthesis processes of seabed natural gas hydrates.

[0066] It should be noted that, in the present invention, the Raman spectrometer is used in conjunction with the rope coring drill, the Raman spectrometer is adapted to the outer tube assembly so as to be able to be put into the outer tube assembly, and the probe can be extended from the drill bit of the rope coring drill to facilitate the detection of the target formation.

[0067] It should also be noted that, in one embodiment of the present invention, the size of the rope salvage device is the same as the size of the rope salvage assembly.

[0068] Step S6, lifting the drill a second time, and using the probe to detect whether there are ice-like crystals in the target formation.

[0069] In this step, the secondary drilling is performed slowly so that the probe can carefully detect the target formation.

[0070] Furthermore, the probe includes a visible light source, a camera, a Raman laser light source and a detector.

[0071] Furthermore, the step S6 specifically includes:

[0072] The visible light source is turned on, the drill is lifted a second time, and the camera is used to observe whether ice-like crystals exist in the target stratum.

[0073] It should be noted that natural gas hydrate is an ice-like crystalline substance, which usually looks like ice. Therefore, the image captured by the camera can be used to preliminarily determine whether natural gas hydrate exists in the target formation.

[0074] Step S7: If the probe does not detect the ice-like crystals, the Raman spectrometer is taken out from the outer tube assembly by using the rope salvage device, and the inner tube assembly is put into the outer tube assembly by using the rope salvage assembly, and steps S2-S6 are repeated.

[0075] In this step, if the ice-like crystals are not found through the shooting results of the camera, it is determined that there is no natural gas hydrate in the target formation in the height space. Therefore, the Raman spectrometer is taken out, the inner tube assembly is put in, and the above steps S2-S6 are repeated to conduct new detection of the target formations in other height spaces.

[0076] Step S8: If the probe detects the ice-like crystals, the potential natural gas hydrate reservoir is located, and laser Raman scanning is performed by the probe to analyze and determine whether natural gas hydrates exist in the target formation, and then the Raman spectrometer is taken out from the outer tube assembly by using the rope salvage assembly, and the inner tube assembly is put into the outer tube assembly by using the rope salvage assembly, and steps S2-S6 are repeated.

[0077] In this step, after the camera makes a preliminary judgment on the presence of the ice-like crystals in the target stratum within a certain height space, a secondary judgment is made through laser Raman scanning to accurately analyze whether there are natural gas hydrates in the target stratum within the height space. After the analysis and judgment are completed, the Raman spectrometer is taken out, the inner tube assembly is put in, and the above steps S2-S6 are repeated to conduct new detection of the target strata in other height spaces.

[0078] For further information, see Figure 2 , the step S8 specifically includes:

[0079] Step S81: If the ice-like crystals are observed by the camera, the potential natural gas hydrate reservoir is located according to the position of the drill bit.

[0080] Step S82, turning off the visible light source, and turning on the Raman laser light source and the detector, performing laser Raman scanning corresponding to the potential natural gas hydrate reservoir location, and transmitting the scanning result to the control terminal for analysis and determination whether natural gas hydrate exists in the target formation.

[0081] Step S83: After the laser Raman scan is completed, turn off the Raman laser light source and the detector, use the rope salvage device to take out the Raman spectrometer from the outer tube assembly, and use the rope salvage assembly to put the inner tube assembly into the outer tube assembly, and repeat steps S2-S6.

[0082] For further information, see Figure 3 , the step S82 specifically includes:

[0083] Step S821, turning off the visible light source, and turning on the Raman laser light source and the detector, performing laser Raman scanning corresponding to the potential natural gas hydrate reservoir location, and transmitting the scanning result to the control terminal for analysis to obtain a Raman spectrum curve.

[0084] Step S822: Determine whether natural gas hydrate exists in the target formation according to the Raman spectrum curve.

[0085] Furthermore, the step S822 specifically includes:

[0086] Whether there is natural gas hydrate in the target formation is determined according to the characteristic peak of the Raman spectrum curve.

[0087] In this step, whether natural gas hydrate exists can be determined based on whether the characteristic peak of the Raman spectrum curve is around 2906 (the Raman characteristic peak of methane hydrate is around 2906).

[0088] Step S823: If natural gas hydrate exists in the target formation, the occurrence state and density characteristics of the natural gas hydrate are analyzed according to the Raman spectrum curve.

[0089] Furthermore, the step S823 specifically includes:

[0090] If natural gas hydrate exists in the target formation, the structural composition, temperature and pressure conditions and density of the natural gas hydrate are obtained according to the height and area of ​​the characteristic peak of the Raman spectrum curve.

[0091] It should be noted that the density of natural gas hydrate is proportional to the area of ​​the characteristic peak of the Raman spectrum curve.

[0092] In the technical solution of the present invention, the rope coring drill and the Raman spectrometer matched therewith are used to detect seabed natural gas hydrates, which can simultaneously realize the drilling and coring of seabed hydrate-containing formations, video observation and in-situ Raman spectrum measurement, real-time determination of the Raman spectrum of the hydrate reservoir under in-situ temperature and pressure conditions, determination of the occurrence state and density characteristics of the hydrate reservoir, and effectively increase the efficiency and accuracy of geological exploration of hydrate-containing formations.

[0093] The present invention also provides an in-situ measurement device for seabed natural gas hydrates, which is applicable to the in-situ measurement method for seabed natural gas hydrates described above. Figures 4 to 6 The seabed natural gas hydrate in-situ measurement device 100 includes a rope coring drill 1, a Raman spectrometer 2, a rope salvage device 3 and a control terminal 4. The rope coring drill 1 includes an inner tube assembly 11, an outer tube assembly 12, a drill bit 13 and a rope salvage assembly 14 (such as Figure 5 As shown), the rope salvage assembly 14 and the inner tube assembly 11 are movably arranged in the outer tube assembly 12, the drill bit 13 is arranged at the bottom end of the outer tube assembly 12, and the inner tube assembly 11 includes a core tube; the Raman spectrometer 2 is used to be detachably arranged in the outer tube assembly 12, including a probe 21, and the probe 21 is used to extend the drill bit 13 through the outer tube assembly 12 to perform Raman spectrum detection (as shown Figure 4 The rope salvage device 3 is used to put in or take out the Raman spectrometer 2 in the outer tube assembly 12; the control terminal 4 is electrically connected to the Raman spectrometer 2.

[0094] Furthermore, the probe 21 includes a visible light source, a camera, a Raman laser light source and a detector. Thus, the visible light source and the camera are used to realize video observation, and the laser light source and the detector are used to realize in-situ Raman spectrum measurement.

[0095] For details, please refer to Figure 4 and Figure 6 The Raman spectrometer 2 further includes a connecting tube 22 , which is extended in the up-down direction, and the probe 21 is connected to the rope salvage device 3 through the connecting tube 22 .

[0096] It should be noted that, in the present invention, the above two technical features can be set selectively or simultaneously. Specifically, in one embodiment of the present invention, the above two technical features are set simultaneously, that is, the probe 21 includes a visible light source, a camera, a Raman laser light source and a detector, and the Raman spectrometer 2 also includes a connecting tube 22, and the connecting tube 22 is extended in the up and down directions, and the probe 21 is connected to the rope salvage device 3 through the connecting tube 22.

[0097] For details, please refer to Figures 1 to 4 In one embodiment of the present invention, a protective shell is further provided on the periphery of the probe 21 to protect the probe structure.

[0098] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for in-situ measurement of seabed natural gas hydrate, characterized in that: The method for in-situ measurement of seabed natural gas hydrate comprises the following steps: Step S1, putting the rope coring drill into the well; Step S2, using the rope coring drill to perform coring drilling on the target formation, and stopping drilling when the core tube in the rope coring drill is full of core; Step S3, using the rope salvage assembly of the rope coring drill to remove the inner tube assembly in the rope coring drill from the outer tube assembly of the rope coring drill, and removing the core tube in the inner tube assembly to preserve the core; Step S4, lifting the drill once and washing the hole with drilling fluid; Step S5, using a rope salvage device to put the Raman spectrometer into the outer tube assembly until the probe of the Raman spectrometer extends out from the drill bit of the rope coring drill; Step S6, lifting the drill for a second time, and using the probe to detect whether there are ice-like crystals in the target formation; Step S7, if the probe does not detect the ice-like crystals, the Raman spectrometer is taken out from the outer tube assembly by using the rope salvage device, and the inner tube assembly is put into the outer tube assembly by using the rope salvage assembly, and steps S2-S6 are repeated; Step S8: If the probe detects the ice-like crystals, the potential natural gas hydrate reservoir is located, and laser Raman scanning is performed by the probe to analyze and determine whether natural gas hydrates exist in the target formation, and then the Raman spectrometer is taken out from the outer tube assembly by using the rope salvage assembly, and the inner tube assembly is put into the outer tube assembly by using the rope salvage assembly, and steps S2-S6 are repeated.

2. The method for in-situ measurement of seabed natural gas hydrate according to claim 1, characterized in that: The probe includes a visible light source, a camera, a Raman laser light source and a detector; The step S6 specifically includes: The visible light source is turned on, the drill is lifted a second time, and the camera is used to observe whether ice-like crystals exist in the target stratum.

3. The method for in-situ measurement of seabed natural gas hydrate according to claim 2, characterized in that: The step S8 specifically includes: Step S81: if the ice-like crystals are observed by the camera, the potential natural gas hydrate reservoir is located according to the position of the drill bit; Step S82, turning off the visible light source, and turning on the Raman laser light source and the detector, performing laser Raman scanning corresponding to the potential natural gas hydrate reservoir position, and transmitting the scanning result to the control terminal for analysis and determination of whether there is natural gas hydrate in the target formation; Step S83: After the laser Raman scan is completed, turn off the Raman laser light source and the detector, use the rope salvage device to take out the Raman spectrometer from the outer tube assembly, and use the rope salvage assembly to put the inner tube assembly into the outer tube assembly, and repeat steps S2-S6.

4. The method for in-situ measurement of seabed natural gas hydrate according to claim 3, characterized in that: The step S82 specifically includes: Step S821, turning off the visible light source, and turning on the Raman laser light source and the detector, performing laser Raman scanning corresponding to the potential natural gas hydrate reservoir position, and transmitting the scanning result to the control terminal for analysis to obtain a Raman spectrum curve; Step S822, judging whether there is natural gas hydrate in the target formation according to the Raman spectrum curve; Step S823: If natural gas hydrate exists in the target formation, the occurrence state and density characteristics of the natural gas hydrate are analyzed according to the Raman spectrum curve.

5. The method for in-situ measurement of seabed natural gas hydrate according to claim 4, characterized in that: The step S822 specifically includes: Whether there is natural gas hydrate in the target formation is determined according to the characteristic peak of the Raman spectrum curve.

6. The method for in-situ measurement of seabed natural gas hydrate according to claim 4, characterized in that: The step S823 specifically includes: If natural gas hydrate exists in the target formation, the structural composition, temperature and pressure conditions and density of the natural gas hydrate are obtained according to the height and area of ​​the characteristic peak of the Raman spectrum curve.

7. The method for in-situ measurement of seabed natural gas hydrate according to claim 1, characterized in that: When the drill is lifted once, the active height of the drill bit is set to L1, the length of the probe is set to L2, and L1≥2L2.

8. The method for in-situ measurement of seabed natural gas hydrate according to claim 1, characterized in that: The drilling fluid includes vegetable gum.

9. An in-situ measurement device for seabed natural gas hydrate, applicable to the in-situ measurement method for seabed natural gas hydrate according to any one of claims 1 to 8, characterized in that: The seabed natural gas hydrate in-situ measurement equipment comprises: A rope coring drill, comprising an inner tube assembly, an outer tube assembly, a drill bit and a rope salvage assembly, wherein the rope salvage assembly and the inner tube assembly are movably arranged in the outer tube assembly, the drill bit is arranged at the bottom end of the outer tube assembly, and the inner tube assembly comprises a core tube; A Raman spectrometer, detachably mounted on the outer tube assembly, comprising a probe, the probe being used to extend through the outer tube assembly and out of the drill bit to perform Raman spectrum detection; a rope salvage device, used for placing or removing the Raman spectrometer in the outer tube assembly; and a control terminal, electrically connected to the Raman spectrometer.

10. The in-situ measurement device for seabed natural gas hydrate according to claim 9, characterized in that: The probe includes a visible light source, a camera, a Raman laser light source and a detector; and / or, The Raman spectrometer further comprises a connecting tube, which is extended in the up-down direction, and the probe is connected to the rope salvage device through the connecting tube.

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