Method, device and system for analyzing formation time of natural gas hydrate reservoir

Abstract

The invention discloses a natural gas hydrate reservoir formation time analysis method, device and system, and relates to the technical field of marine natural gas hydrate exploration, and the formation time analysis method comprises the following steps: collecting a marine sediment sample in a natural gas hydrate drilling core column; carrying out a photoluminescence age test on the marine sediment sample; establishing an age-depth model of the natural gas hydrate sample according to the obtained photoluminescence age and sediment depth of the ocean sediment sample; and according to the age-depth model of the natural gas hydrate drilling, calculating the reservoir deposition time of the natural gas hydrate, and further determining the formation age of the natural gas hydrate. According to the method, the formation time of the natural gas hydrate can be accurately determined, interference caused by uncertain reservoir forming time of the natural gas hydrate is avoided, and a geological exploration foundation is laid for further revealing a reservoir forming mechanism of the natural gas hydrate.

Description

Technical Field

[0001] The present invention relates to the technical field of marine natural gas hydrate exploration, and more specifically to a method, device and system for analyzing the formation age of a natural gas hydrate reservoir. Background Art

[0002] Natural gas hydrates have the characteristics of wide distribution, large reserves, high calorific value and high energy density. As an energy resource, they have attracted widespread attention from countries around the world.

[0003] The research area of ​​natural gas hydrates in my country is mainly in the northern part of the South China Sea, where the types of hydrate systems are diverse and the accumulation process is complex.

[0004] A large number of studies on natural gas hydrates mainly include six major factors: temperature and pressure conditions, gas source conditions, water source conditions, gas migration channels, storage conditions and time. In particular, the formation time of natural gas hydrates is the key to determining whether the first five factors can be reasonably matched in the entire reservoir formation process of the natural gas hydrate system. Previous researchers determined the static conditions of the reservoir formation system based on seismic, well logging and geochemical analysis methods, but there are few reports on the research on the formation time of natural gas hydrates.

[0005] Due to the lack of sample carriers and methods to directly determine the age of natural gas hydrate formation, how to obtain more accurate hydrate formation time and then reveal the hydrate accumulation mechanism has always been a research difficulty that urgently needs to be tackled in the field of hydrate accumulation.

[0006] Therefore, in order to determine the formation time of natural gas hydrates in the sea and reveal the mechanism of natural gas hydrate accumulation, it is urgent to invent a fast, accurate and efficient analysis method. Summary of the invention

[0007] In view of this, an object of the present invention is to provide a method, device and system for analyzing the formation age of a natural gas hydrate reservoir, so as to solve the technical problem that the formation age of natural gas hydrates cannot be directly determined in the prior art.

[0008] To achieve the above object, the first object of the present invention is to provide a method for analyzing the formation age of a natural gas hydrate reservoir, comprising the steps of:

[0009] Step S 100 : Collecting marine sediment samples in gas hydrate drill core columns;

[0010] Step S 200 : Performing an optically stimulated luminescence age test on the marine sediment sample to obtain the optically stimulated luminescence age of the marine sediment sample;

[0011] Step S 300: According to the obtained optically stimulated luminescence age of the marine sediment sample and the sediment depth of the marine sediment sample, an age-depth model of the natural gas hydrate sample is established. The age-depth model of the natural gas hydrate drilling core column sample is:

[0012]

[0013] in: is the predicted age of the gas hydrate core column sample at depth x, Yi is the measured age of the ith drill core column sample, and Wi(x) is the weight of the ith drill core column sample at depth x;

[0014] Step S 400 :Based on the age-depth model of gas hydrate core column samples, the deposition time of the gas hydrate reservoir is calculated, and then the formation age of the gas hydrate reservoir is determined.

[0015] Preferably, in step S 100 The specific steps of collecting marine sediment samples for natural gas hydrate drilling core column samples include:

[0016] Step S 110 : Obtain core column samples of gas hydrate boreholes from the strata below the seafloor by means of a drilling vessel;

[0017] Step S 120 : Under light-proof conditions, the core columnar sample is cut into a number of core segments at certain length intervals, and the core segments are sealed and stored in light-proof aluminum foil bags, and the aluminum foil bags are numbered;

[0018] Step S 130 : Place the aluminum foil bag in a special light-proof sample box and transport it to the laboratory for light-proof storage.

[0019] Preferably, in step S 200 The step of conducting optically stimulated luminescence age testing on the marine sediment sample comprises:

[0020] Step S 210 : Quartz grain samples were prepared from core sections;

[0021] Step S 220 : Place the quartz particle sample on an aluminum sheet for testing;

[0022] Step S 230 : Using a single-chip regeneration dose method to perform equivalent dose measurement on a luminescence analyzer on the quartz particle sample to obtain a sediment sample;

[0023] Step S 240: Determining the environmental dose rate of the sediment sample by a high purity germanium gamma spectrometer, and simultaneously determining the water content of the sediment sample;

[0024] Step S 250 : Calculate the luminescence age of the sediment sample to obtain the absolute geological age of the sediment sample, where the luminescence age = equivalent dose / environmental dose rate.

[0025] Preferably, in step S 210 The step of preparing a quartz grain sample from a core segment includes:

[0026] Step S 211 : In the laboratory, a sediment sample with a mass of m0 is taken from the middle part of each core section, and a core particle sample is obtained after removing organic matter and carbonate minerals in the sediment sample using a 30% H2O2 solution and 10% HCl;

[0027] Step S 212 : extracting a fine particle sample of 4-11 μm from the core particle sample according to the Stokes sedimentation principle;

[0028] Step S 213 : Put the fine particle sample into a centrifuge tube, add 35 ml of 30% H2SiF6 fluorosilicic acid, and stir continuously on a mixer for 3-5 days to remove feldspar minerals to obtain a core sample mixed solution;

[0029] Step S 214 : Then, washing the core sample mixed solution with 30% HCl for 30-120 min to completely remove fluoride to obtain a core sample solution;

[0030] Step S 215 : The core sample solution is washed with clean water until it is neutral, and then placed in an oven for drying to obtain a quartz particle sample.

[0031] Preferably, in step S 300 The method for establishing an age-depth model of a natural gas hydrate core column sample specifically includes:

[0032] Calculate bandwidth;

[0033] h=S PAN ×X d

[0034] Where: S PAN represents the smoothing parameter, X d Represents the difference between the maximum depth and the minimum depth of the sample, X d =X max -X min , Xmax is the maximum depth of the sample, X min is the minimum depth of the sample;

[0035] Calculate the value of X for each data point at a specific depth X i The kernel function value of

[0036]

[0037] K h (XX i ) represents the kernel function value of the i-th sample at depth X, X i is the depth value of the i-th sample;

[0038] Calculate the sum of weights:

[0039]

[0040] W is the sum of weights, n is the total number of samples;

[0041] Calculate the value of X for each data point at a specific depth x i Weight:

[0042]

[0043] W i (x) is the weight of the i-th sample at depth x;

[0044] Based on the measured age, predicted age and their depth relationship, an age-depth model of natural gas hydrate core samples was established.

[0045] Preferably, in step S 400 The specific steps of calculating the deposition time of the gas hydrate reservoir and then determining the formation age of the gas hydrate include:

[0046] Step S 410 :Combining the age-depth model of gas hydrate core column samples and the gas hydrate reservoir depth, the deposition time of gas hydrate reservoir is calculated;

[0047] Step S 420 :The age of natural gas hydrate formation can be determined based on the deposition time of the natural gas hydrate reservoir.

[0048] The second object of the present invention is to provide a formation age analysis device for a natural gas hydrate reservoir, using the formation age analysis method for a natural gas hydrate reservoir described above, the analysis device comprises:

[0049] Sample collection module, used to collect and analyze core data;

[0050] A sample testing module, used to perform optically stimulated luminescence age testing and analysis based on the prepared marine sediment samples;

[0051] A model building module is used to build an age-depth model of natural gas hydrate samples based on the obtained optically stimulated luminescence age and sediment depth of the marine sediment samples;

[0052] The analysis module is used to calculate the deposition time of gas hydrate reservoirs based on the age-depth model of gas hydrate drilling, and then determine the formation age of gas hydrates.

[0053] The third object of the present invention is to provide a formation age analysis system for a natural gas hydrate reservoir, using the formation age analysis method for a natural gas hydrate reservoir described above, the analysis system comprising:

[0054] one or more processors;

[0055] A storage device for storing one or more programs;

[0056] When the one or more programs are executed by the one or more processors, the one or more processors implement the formation age analysis method of the natural gas hydrate reservoir as described above.

[0057] Compared with the prior art, the present invention has the following advantages and effects:

[0058] The formation age analysis method of the natural gas hydrate reservoir in this application targets the marine sediments collected in the dark, collects marine sediment samples in the core column of the natural gas hydrate drilling, performs optically stimulated luminescence age test on the marine sediment samples, and obtains the optically stimulated luminescence age of the marine sediment samples; the age-depth model of the natural gas hydrate drilling is established by the optically stimulated luminescence chronology test method, and the natural gas hydrate reservoir deposition time is determined in combination with the reservoir depth of the natural gas hydrate, and finally the formation age of the natural gas hydrate is determined. This method can quickly determine the age of the sediments in the deeper strata of the Quaternary, can accurately determine the deposition time of the Quaternary natural gas hydrate reservoir in the sea area, and can effectively determine the formation age of the natural gas hydrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 Schematic diagram of the process of the formation age analysis method of the natural gas hydrate reservoir in an embodiment of the present invention;

[0060] Figure 2 Step S in the embodiment of the present invention 100 Detailed process diagram of

[0061] Figure 3 Step S in the embodiment of the present invention 200 Detailed process diagram of

[0062] Figure 4 Schematic diagram of the structure of a formation age analysis device for a natural gas hydrate reservoir in an embodiment of the present invention;

[0063] Figure 5 Schematic diagram of the structure of the formation age analysis system of the natural gas hydrate reservoir in an embodiment of the present invention;

[0064] Figure 6 A schematic diagram of a curve between the age and depth of natural gas hydrate drilling in the Qiongdongnan Basin in an embodiment of the present invention;

[0065] Figure 7 This is a schematic diagram of the comprehensive interpretation of borehole logging and seismic for natural gas hydrate in the Qiongdongnan Basin in an embodiment of the present invention. DETAILED DESCRIPTION

[0066] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. 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.

[0067] In the description of the present invention, it should be noted that the terms "include" and "comprises" used herein should be understood as inclusive and open-ended, rather than exclusive. Specifically, when the terms "include" and "comprises" and their synonyms are used in the specification and claims, they mean including the specified features, steps or components. These terms cannot be understood to exclude the existence of other features, steps or components.

[0068] OSL dating is the determination of the age of the last exposure (or heat) event of sediments. Its test objects are mainly quartz and feldspar minerals. The energy accumulated by the sediment mineral crystals since the last burial due to the radiation of surrounding radioactive substances is released in the form of light mainly through the excitation of light beams. This is the luminescence signal. The age of the sample since the last burial can be obtained by measuring the intensity of the luminescence signal. The dating range is tens to hundreds of thousands of years, and the dating accuracy is 5-10%. OSL dating technology is one of the most commonly used and recognized dating technologies at present. It is widely used in archaeology, active tectonics, paleo-earthquakes and other studies.

[0069] See also Figure 1-5 As shown, in one embodiment, the present invention provides a method for analyzing the formation age of a natural gas hydrate reservoir, the method comprising the steps of:

[0070] Step S 100: Collecting marine sediment samples in gas hydrate drill core columns;

[0071] In this step, it needs to be explained that the natural gas hydrate drilling core column refers to a core column sample obtained by an ocean drilling ship in the stratum below the seabed, and the core column sample is formed in a drilling plastic casing.

[0072] Step S 200 : Performing an optically stimulated luminescence age test on the marine sediment sample to obtain the optically stimulated luminescence age of the marine sediment sample;

[0073] In this step, it is necessary to explain that luminescence is a physical phenomenon in which crystalline minerals such as quartz and feldspar release energy in the mineral lattice in the form of photons after being exposed to high temperature or light. In luminescence dating of geological samples, the two mineral components of quartz and feldspar are mainly measured.

[0074] The principle of luminescence dating is to calculate the burial age of the sample by using the radioactive dose accumulated in the sample quartz grains and the annual dose rate provided by the sample burial environment.

[0075] Step S 300 : According to the obtained optically stimulated luminescence age of the marine sediment sample and the sediment depth of the marine sediment sample, an age-depth model of the natural gas hydrate drilling core column sample is established, and the age-depth model of the natural gas hydrate drilling core column sample is:

[0076]

[0077] in: is the predicted age of the natural gas hydrate core column sample at depth x, Yi is the measured age of the ith drill core column sample, and Wi(x) is the weight of the ith drill core column sample at depth x.

[0078] Step S 400 :Based on the age-depth model of gas hydrate core column samples, the deposition time of the gas hydrate reservoir is calculated, and then the formation age of the gas hydrate reservoir is determined.

[0079] It should be noted that natural gas hydrate is a solid crystalline substance formed by the combination of water and natural gas under specific temperature and pressure conditions.

[0080] For further information, see Figure 2 As shown, in one embodiment, step S 100 The specific steps of collecting marine sediment samples in the natural gas hydrate drilling core column include:

[0081] Step S 110: Obtaining core column samples of gas hydrate drill core columns from the formation below the seabed by means of a drilling vessel;

[0082] Step S 120 : Under light-proof conditions, the core columnar sample is cut into a number of core segments at certain length intervals, and the core segments are sealed and stored in light-proof aluminum foil bags, and the aluminum foil bags are numbered;

[0083] Step S 130 :Put the aluminum foil bag in a special light-proof sample box and transport it to the laboratory for light-proof storage. In the process of obtaining marine sediment samples, natural gas hydrate cores are drilled in the ocean using drilling ships or drilling platforms due to the particularity of their formation and preservation conditions. By using drilling plastic casings and aluminum foil bags, sampling operations are carried out for the purpose of obtaining undisturbed natural gas hydrate samples on the seabed or cores of reservoirs containing natural gas hydrates.

[0084] It needs to be explained that marine sediments refer to the general term for seabed sediments formed by various marine sedimentation processes. It is a substance deposited on the seabed with seawater as the medium.

[0085] For further information, see Figure 3 As shown, in one embodiment, step S 200 The step of conducting optically stimulated luminescence age testing on the marine sediment sample comprises:

[0086] Step S 210 : Quartz grain samples were prepared from core sections;

[0087] Step S 220 : Place the quartz particle sample on an aluminum sheet for testing;

[0088] Step S 230 : Using a single-chip regeneration dose method to perform equivalent dose measurement on a luminescence analyzer on the quartz particle sample to obtain a sediment sample;

[0089] Step S 240 : Determining the environmental dose rate of the sediment sample by a high purity germanium gamma spectrometer, and simultaneously determining the water content of the sediment sample;

[0090] Step S 250 : Calculate the luminescence age of the sediment sample to obtain the absolute geological age of the sediment sample, where the luminescence age = equivalent dose / environmental dose rate.

[0091] Furthermore, in one embodiment, step S 210 The step of preparing a quartz grain sample from a core segment includes:

[0092] Step S211 : In the laboratory (dark room), a marine sediment sample with a mass of m0 was taken from the middle part of each core section, and the organic matter and carbonate minerals in the marine sediment sample were removed using a 30% H2O2 solution and a 10% HCl solution to obtain a core particle sample.

[0093] In this step, since the sediments stored at both ends of the drilling plastic casing pipe may be affected by exposure during the sampling process, marine sediment samples are taken from the middle part of each core section and pre-processed.

[0094] Quartz of qualified purity was extracted by removing organic matter and carbonate minerals from marine sediment samples using a 30% hydrogen peroxide solution (H2O2) and a 10% hydrochloric acid (HCl).

[0095] Step S 212 : According to the Stokes sedimentation principle, fine particle samples of 4-11 μm are extracted from the core particle samples.

[0096] It is necessary to explain here that the so-called Stokes sedimentation principle is a physical phenomenon based on Stokes' law, which describes the relationship between the sedimentation velocity of particles in viscous fluids and the size, density and viscosity of the particles. This principle is of great significance for understanding and analyzing many natural phenomena and industrial processes.

[0097] In the same fluid, larger and heavier particles will settle faster than smaller and lighter particles. In addition, if the viscosity of the liquid is greater, the settling rate of the particles will slow down, causing the particles to take longer to settle.

[0098] After a period of sedimentation of the core particle samples, fine particle samples with a particle size of 4-11um can be obtained.

[0099] Step S 213 : The fine particle sample is placed in a centrifuge tube, 35 ml of 30% fluorosilicic acid (H2SiF6) is added, and the mixture is continuously stirred on a mixer for 3-5 days to remove feldspar minerals to obtain a core sample mixed solution.

[0100] In this step, the feldspar particles in the fine-grained sample will be dissolved by fluorosilicic acid to remove the feldspar minerals.

[0101] Step S 214 : Then, the core sample mixed solution is washed with 30% HCl for 30-120 minutes to completely remove fluoride to obtain a core sample solution.

[0102] In this step, 30% hydrochloric acid (HCl) is used to neutralize the core sample mixed solution for more than two times to remove fluoride.

[0103] Step S 215 : The core sample solution is washed with clean water until it is neutral, and then placed in an oven for drying to obtain a quartz particle sample.

[0104] Therefore, before performing equivalent dose measurement, luminescence property experiments such as quartz purity detection, preheating plateau and dose recovery are carried out to determine the luminescence analysis parameters and procedures.

[0105] Furthermore, in one embodiment, step S 300 The method for establishing an age-depth model of a natural gas hydrate core column sample specifically includes:

[0106] Step 1: Calculate bandwidth;

[0107] h=S PAN ×X d

[0108] Where: S PAN represents the smoothing parameter, X d represents the difference between the maximum and minimum depths of the gas hydrate core column sample, X d =X max -X min , X max is the maximum depth of the gas hydrate core sample, X min Minimum depth for sampling gas hydrate cores.

[0109] Step 2: Calculate the kernel function value of the i-th drill core column sample at a specific depth X;

[0110]

[0111] Where: K h (XX i ) represents the kernel function value of the i-th sample at depth X, X i is the depth value of the i-th natural gas hydrate drilling core column sample.

[0112] Step 3: Calculate the sum of weights:

[0113]

[0114] Where: W is the total weight and n is the total number of samples.

[0115] Step 4: Calculate the value of each data point X at a specific x depth i Weight:

[0116]

[0117] Where: W i (x) is the weight of the i-th sample at depth x.

[0118] Finally, an age-depth model of natural gas hydrate core samples was established based on the measured age, predicted age and their depth relationship.

[0119] It should be explained that the so-called equivalent dose refers to the radiation dose accumulated since the last time the sample was fully exposed (or thermal event). This dose comes from the radioactive substances in the environment around the sample, such as the decay of natural radioactive elements such as uranium (U), thorium (Th) and potassium (K), as well as cosmic rays.

[0120] Method for measuring equivalent dose:

[0121] Single-piece regeneration dose method: This is a commonly used method for measuring equivalent doses, which is applicable to quartz and feldspar particles. In this method, each sample is divided into multiple single pieces (or test pieces), and each single piece is individually measured for its natural luminescence signal and a series of regeneration dose signals of different doses. By establishing a dose recovery curve, the natural luminescence signal is projected onto this curve to obtain the equivalent dose.

[0122] Factors affecting equivalent dose measurement:

[0123] Purity of the sample: Impurities in the sample may affect the stability and intensity of the luminescence signal.

[0124] Thermal history of the sample: If the sample has experienced high temperature or light exposure events, it may affect its luminescence signal.

[0125] Laboratory conditions: The preheating temperature during the measurement process, the intensity and duration of the excitation light source, etc. will affect the measurement results.

[0126] Environmental factors: The environment in which the sample is located, such as humidity, temperature, and chemical conditions, may affect the accumulation of radiation dose.

[0127] Further, in step S of one embodiment 400 The specific steps of calculating the deposition time of the gas hydrate reservoir and then determining the formation age of the gas hydrate include:

[0128] Step S 410 :Combining the age-depth model of gas hydrate drilling and the depth of gas hydrate reservoir, the deposition time of gas hydrate reservoir is calculated;

[0129] Step S 420:The age of natural gas hydrate formation can be determined based on the deposition time of the natural gas hydrate reservoir.

[0130] On the other hand, see Figure 4 As shown, in one embodiment, the present invention further provides a formation age analysis device for a natural gas hydrate reservoir, the age analysis device comprising:

[0131] Sample collection module, used to collect and analyze core data;

[0132] A sample testing module, used to perform optically stimulated luminescence age testing and analysis based on the prepared marine sediment samples;

[0133] A model building module is used to build an age-depth model of a natural gas hydrate core column sample based on the optically stimulated luminescence age and sediment depth of the obtained marine sediment sample;

[0134] The analysis module is used to calculate the deposition time of the gas hydrate reservoir based on the age-depth model of the gas hydrate core column sample, and then determine the formation age of the gas hydrate.

[0135] On the other hand, in one embodiment, see Figure 5 As shown, Figure 5 A structural diagram of a natural gas hydrate reservoir formation age analysis system provided in one embodiment of the present application.

[0136] The formation age analysis system of the natural gas hydrate reservoir comprises a processor, a memory and a bus. The memory stores machine-readable instructions executable by the processor. When the analysis system is running, the processor communicates with the memory via the bus. When the machine-readable instructions are executed by the processor, the above-mentioned Figure 1 The specific implementation of the steps of the method for analyzing the formation age of the natural gas hydrate reservoir in the method embodiment shown can be found in the method embodiment, and will not be repeated here.

[0137] On the other hand, in one embodiment, the present application also provides a computer-readable storage medium on which a computer program is stored, and the computer program can be executed as described above when the processor is running. Figure 1 The specific implementation of the steps of the method for analyzing the formation age of the natural gas hydrate reservoir in the method embodiment shown can be found in the method embodiment, and will not be repeated here.

[0138] In the several embodiments provided in the present application, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the functional units in the various embodiments of the present application can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0139] like Figure 6 , 7 As shown, taking the Qiongdongnan Basin in the northern South China Sea as an example, the formation age of the natural gas hydrate reservoir in the Qiongdongnan Basin in the northern South China Sea was determined by the above-mentioned natural gas hydrate reservoir formation age analysis method.

[0140] The specific implementation process is as follows:

[0141] Step 1: Collect marine sediment samples;

[0142] Step 1: After the drilling ship obtains the deep-sea core column sample of the natural gas hydrate drilling core column from the strata below the seabed in the Qiongdongnan Basin in the northern South China Sea, it must be protected from light. Then, the columnar sample is cut into 20 cm long core segments together with the drilling plastic casing at intervals of more than 1 meter, for a total of 14 core segments. Then, it is sealed in a light-proof aluminum foil bag and marked with sample numbers, from 1H-1 to 11H-4c, and placed in a special light-proof sample box to avoid accidental exposure during transportation. It is then immediately transported to the laboratory (darkroom) for light-proof storage.

[0143] Step 2: OSL age test analysis of marine sediment samples;

[0144] Step 2: In a dark room, approximately 150 g of sediment samples were taken from the middle part of each of the 14 core section sample tubes, and organic matter and carbonate minerals in each sample were removed in turn using a 30% H2O2 solution and 10% HCl.

[0145] Step 3: Extract the 4-11 μm fine particle sample from each sample based on the Stokes sedimentation principle.

[0146] Step 4: Place the 4-11 μm fine particle samples of each sample into centrifuge tubes, add 35 ml of 30% H2SiF6 fluorosilicic acid, and stir the samples on a mixer for 3-5 days to remove the feldspar minerals in each sample.

[0147] Step 5: Wash the samples with 30% HCl for 30 minutes to 2 hours to remove fluoride from each sample.

[0148] Step 6: Wash each sample with clean water until it becomes neutral and place it in a 40°C oven to dry.

[0149] Step 7: Place the purified quartz particle samples on a round aluminum sheet with a diameter of about 1 cm in the sample order for testing.

[0150] Step 8: Apply the single-chip regeneration dose method to the treated pure quartz particle sample in a luminescence analyzer (model -TL / OSL-DA-20C / D) to perform equivalent dose measurements.

[0151] Step 9: The environmental dose rate of each sediment sample will be measured mainly using a high purity germanium gamma spectrometer (HPGe Gamma Spectrometer).

[0152] Step 10: The moisture content of each sample will be determined based on the measured moisture content and saturated moisture content, taking into account its sedimentation and burial process to ensure the measurement accuracy of the environmental dose rate.

[0153] Step 11: Calculate the photoluminescence age of the sediment sample: luminescence age = equivalent dose / environmental dose rate. This age is the absolute geological age of the sediment (Table 1).

[0154] Table 1 Results of OSL dating of natural gas hydrates in the Qiongdongnan Basin

[0155]

[0156]

[0157] Step 3: Based on the OSL age of the marine sediments obtained in step 2, establish the age-depth model of the borehole;

[0158] Step 12: Based on the sediment depth and OSL age, combined with the natural gas hydrate core column, the age-depth model of the core column sample is established using the local weighted regression calculation method. The specific process is as follows:

[0159] Select a suitable smoothing parameter SPAN value such as 0-0.5; through computer calculation, for example, the predicted age at 22 meters below the seabed is about 47.5ka, and the predicted age at 70 meters below the seabed is about 116.2ka; based on the measured age and the predicted age and their depth relationship, an age-depth model of the drill core column sample can be established;

[0160] Step 4: Combine the age-depth model of the drill core column sample obtained in step 3 to determine the deposition time of the natural gas hydrate reservoir and then determine the age of natural gas hydrate formation.

[0161] Step 13: Combining the age-depth model of the drill core sample and the gas hydrate reservoir depth, the deposition time of the gas hydrate reservoir can be determined. Combining well logging-seismic data ( Figure 7 ), it can be seen that the natural gas hydrate in the borehole is mainly distributed in the 22mbsf-70mbsf, 78mbsf-106mbsf and 122mbsf-136mbsf intervals.

[0162] According to the age-depth model of the core column sample of the drill hole established in this study, the deposition time of the upper natural gas hydrate reservoir is about 47.5ka-116.2ka; the deposition time of the middle and lower sections is unknown.

[0163] Step 14: Since gas hydrates are formed after the deposition of the gas hydrate reservoir, the age of gas hydrate formation can be determined based on the deposition time of the gas hydrate reservoir.

[0164] According to the sedimentation time of the natural gas hydrate reservoir in the borehole, the upper section is mainly 47.5ka-116.2ka, so the latest formation age of the natural gas hydrate in the borehole can be determined to be 47.5ka to the present.

[0165] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for analyzing the formation age of a natural gas hydrate reservoir, characterized in that: Includes steps: Step S 100 : Collecting marine sediment samples in gas hydrate drill core columns; Step S 200 : Performing an optically stimulated luminescence age test on the marine sediment sample to obtain the optically stimulated luminescence age of the marine sediment sample; Step S 300 : According to the obtained optically stimulated luminescence age of the marine sediment sample and the sediment depth of the marine sediment sample, an age-depth model of the natural gas hydrate drilling core column sample is established, and the age-depth model of the natural gas hydrate drilling core column sample is: in: is the predicted age of the gas hydrate core column sample at depth x, wi(x) is the weight of the ith drill core column sample at depth x, and Yi is the measured age of the ith drill core column sample; Step S 400 :Based on the age-depth model of gas hydrate core column samples, the deposition time of the gas hydrate reservoir is calculated, and then the formation age of the gas hydrate reservoir is determined.

2. The method for analyzing the formation age of a natural gas hydrate reservoir according to claim 1, characterized in that: In step S 100 The specific steps of collecting marine sediment samples for natural gas hydrate drilling core column samples include: Step S 110 : Obtain core column samples of gas hydrate boreholes from the strata below the seafloor by means of a drilling vessel; Step S 120 : Under light-proof conditions, the core columnar sample is cut into a number of core segments at certain length intervals, and the core segments are sealed and stored in light-proof aluminum foil bags, and the aluminum foil bags are numbered; Step S 130 : Place the aluminum foil bag in a special light-proof sample box and transport it to the laboratory for light-proof storage.

3. The method for analyzing the formation age of a natural gas hydrate reservoir according to claim 1, characterized in that: In step S 200 The step of conducting optically stimulated luminescence age testing on the marine sediment sample comprises: Step S 210 : Quartz grain samples were prepared from core sections; Step S 220 : Place the quartz particle sample on an aluminum sheet for testing; Step S 230 : Using a single-chip regeneration dose method to perform equivalent dose measurement on a luminescence analyzer on the quartz particle sample to obtain a sediment sample; Step S 240 : Determining the environmental dose rate of the sediment sample by a high purity germanium gamma spectrometer, and simultaneously determining the water content of the sediment sample; Step S 250 : Calculate the luminescence age of the sediment sample to obtain the absolute geological age of the sediment sample, where the luminescence age = equivalent dose / environmental dose rate.

4. The method for analyzing the formation age of a natural gas hydrate reservoir according to claim 3, characterized in that: In step S 210 The step of preparing a quartz grain sample from a core segment is include: Step S 211 : In the laboratory, a sediment sample with a mass of m0 is taken from the middle part of each core section, and a core particle sample is obtained after removing organic matter and carbonate minerals in the sediment sample using a 30% H2O2 solution and 10% HCl; Step S 212 : extracting a fine particle sample of 4-11 μm from the core particle sample according to the Stokes sedimentation principle; Step S 213 : Put the fine particle sample into a centrifuge tube, add 35 ml of 30% H2SiF6 fluorosilicic acid, and stir continuously on a mixer for 3-5 days to remove feldspar minerals to obtain a core sample mixed solution; Step S 214 : Then, washing the core sample mixed solution with 30% HCl for 30-120 min to completely remove fluoride to obtain a core sample solution; Step S 215 : The core sample solution is washed with clean water until it is neutral, and then placed in an oven for drying to obtain a quartz particle sample.

5. The method for analyzing the formation age of a natural gas hydrate reservoir according to claim 1, characterized in that: In step S 300 The method for establishing an age-depth model of a natural gas hydrate core column sample specifically includes: Calculate bandwidth; h=S PAN ×X d Where: S PAN represents the smoothing parameter, X d represents the difference between the maximum and minimum depths of the gas hydrate core column sample, X d =X max -X min , X max is the maximum depth of the natural gas hydrate core column sample, X min Minimum depth of core sample for gas hydrate drilling; Calculate the X value of the i-th drill core sample at a specific depth X. i The kernel function value of K h (XX i ) represents the kernel function value of the i-th sample at depth X, X i is the depth value of the i-th gas hydrate drilling core column sample; Calculate the sum of weights: W is the sum of weights, n is the total number of samples; Calculate the value of X for each data point at a specific depth x i Weight: W i (x) is the weight of the i-th sample at depth x; Based on the measured age, predicted age and their depth relationship, an age-depth model of natural gas hydrate samples is established.

6. The method for analyzing the formation age of a natural gas hydrate reservoir according to claim 1, characterized in that: In step S 400 The specific steps of calculating the deposition time of the gas hydrate reservoir and then determining the formation age of the gas hydrate include: Step S 410 :Combining the age-depth model of gas hydrate core column samples and the gas hydrate reservoir depth, the deposition time of gas hydrate reservoir is calculated; Step S 420 :The age of natural gas hydrate formation is determined based on the deposition time of the natural gas hydrate reservoir.

7. A formation age analysis device for a natural gas hydrate reservoir, using the formation age analysis method for a natural gas hydrate reservoir as claimed in any one of claims 1 to 6, characterized in that: include: Sample collection module, used to collect and analyze core data; A sample testing module, used to perform optically stimulated luminescence age testing and analysis based on the prepared marine sediment samples; A model building module is used to build an age-depth model of a natural gas hydrate core column sample based on the optically stimulated luminescence age and sediment depth of the obtained marine sediment sample; The analysis module is used to calculate the deposition time of the gas hydrate reservoir based on the age-depth model of the gas hydrate core column sample, and then determine the formation age of the gas hydrate.

8. A system for analyzing the formation age of a natural gas hydrate reservoir, using the method for analyzing the formation age of a natural gas hydrate reservoir as claimed in any one of claims 1 to 6, characterized in that: The analysis system comprises: one or more processors; A storage device for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors implement the formation age analysis method of the natural gas hydrate reservoir as described in any one of claims 1-6.

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