Method for identifying organic matter source in reduced color sand body of sandstone uranium mine

Abstract

The application relates to a method for analyzing a geological body by means of physical and chemical properties of the geological body, and particularly relates to a method for identifying the source of organic matter in a reduced-color sand body of a sandstone uranium mine, which comprises the following steps: collecting a reduced-color sand body sample containing uranium in an oxidized-color sedimentary formation; determining the type of organic matter in the reduced-color sand body sample; and determining that the reduced-color sand body sample contains organic matter from a stratum below the oxidized-color sedimentary formation, wherein if the type of organic matter in the reduced-color sand body sample comprises at least one of hydrocarbon, geopetrum and sapropel type kerogen, it is determined that the reduced-color sand body sample contains organic matter from the stratum below the oxidized-color sedimentary formation. According to the method, it can be determined more accurately whether the reduced-color sand body contains organic matter from the stratum below the oxidized-color sedimentary formation, thereby providing a basis for determining whether the sandstone uranium mine is a seepage type sandstone uranium mine.

Description

Technical Field

[0001] This application relates to a method for analyzing geological bodies by utilizing their physical and chemical properties, specifically a method for identifying the source of organic matter in reduced-color sand bodies of sandstone uranium deposits. Background Technology

[0002] In the theory of leaching mineralization, reduced-colored sand bodies in primary oxide formations are formed under the influence of reducing fluids seeping from deep organic-rich strata. Simultaneously, uranium mineralization occurs at the interfaces of the reduced-colored sand bodies under the influence of these reducing fluids. A crucial basis for confirming the existence of leaching mineralization is the presence of organic matter originating from deep strata within the reduced-colored sand bodies. Therefore, there is an urgent need for an accurate and efficient method to identify the source of organic matter to guide the identification of leaching sandstone uranium deposits. Summary of the Invention

[0003] In view of the above problems, this application is made in order to provide a method for identifying the source of organic matter in reduced-color sand bodies of sandstone uranium deposits that overcomes or at least partially solves the above problems.

[0004] Embodiments of this application provide a method for identifying the source of organic matter in reduced-colored sand bodies of sandstone uranium deposits, comprising: collecting uranium-bearing reduced-colored sand body samples from oxidized sedimentary formations; determining the type of organic matter in the reduced-colored sand body samples; determining that the reduced-colored sand body samples contain organic matter originating from the strata beneath the oxidized sedimentary formations, wherein if the type of organic matter in the reduced-colored sand body samples includes at least one of hydrocarbons, bituminous asphalt, and saprophytic kerogen, then it is determined that the reduced-colored sand body samples contain organic matter originating from the strata beneath the oxidized sedimentary formations.

[0005] The method for identifying the source of organic matter in reduced-color sand bodies of sandstone uranium deposits according to the embodiments of this application can accurately identify whether there is organic matter in the reduced-color sand bodies originating from the strata beneath the oxidized-color sedimentary formations, thereby providing a basis for determining whether sandstone uranium deposits are exudative sandstone uranium deposits. Attached Figure Description

[0006] Figure 1 This is a flowchart of a method for identifying the source of organic matter in reduced-color sand bodies of sandstone uranium ore according to an embodiment of this application; Figure 2 This is a schematic diagram of the laser Raman spectroscopy analysis results of organic debris according to an embodiment of this application; Figure 3 A fluorescence microscope image of a reduced-color sand sample according to an embodiment; Figure 4 This is a schematic diagram of the plotting results of acid hydrolysis hydrocarbon analysis according to an embodiment of this application; Figure 5 This is a schematic diagram of the gas chromatography analysis results of saturated hydrocarbons according to an embodiment of this application. Detailed Implementation

[0007] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only one embodiment of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on the described embodiments of this application without creative effort are within the scope of protection of this application.

[0008] It should be noted that, unless otherwise defined, the technical or scientific terms used in this application should have the ordinary meaning understood by a person with ordinary skill in the art to which this application pertains. Where the terms "first," "second," etc., are used throughout the text, they are used only to distinguish similar objects and should not be construed as indicating or implying their relative importance, order of precedence, or implicitly specifying the number of technical features indicated. It should be understood that the data in the descriptions of "first," "second," etc., can be interchanged where appropriate. Where "and / or" appears throughout the text, it means that it includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution that simultaneously satisfies A and B.

[0009] Embodiments of this application provide a method for identifying the source of organic matter in reduced-color sand bodies of sandstone uranium ore, referring to... Figure 1 ,include: Step S102: Collect uranium-containing reduced-color sand body samples from the oxide-colored sedimentary formation.

[0010] Step S104: Determine the type of organic matter in the reduced-color sand sample.

[0011] Step S106: Determine that the reduced-color sand body sample contains organic matter originating from the strata beneath the oxidized-color sedimentary formation. Specifically, if step S104 determines that the type of organic matter in the reduced-color sand body sample includes at least one of hydrocarbons, bitumen, and saprophytic kerogen, then step S106 can determine that the reduced-color sand body sample contains organic matter originating from the strata beneath the oxidized-color sedimentary formation.

[0012] In the theory of leaching mineralization, reduced sand bodies in primary oxidized sedimentary formations are formed under the action of reducing fluids seeping from deep organic-rich strata. At the same time, uranium mineralization occurs at the interface of the reduced sand bodies under the action of reducing fluids. Based on this theory, if uranium-bearing reduced sand bodies are developed in oxidized sedimentary formations, it is necessary to further confirm whether the uranium ore in the uranium-bearing reduced sand bodies is an leaching sandstone uranium ore, in order to avoid misinterpreting or missing ore deposits by using other mineralization theories such as leaching mineralization theory.

[0013] Therefore, in step S102, a sample of uranium-bearing reduced sand body is collected from the oxidized sedimentary formation to identify the source of organic matter in the reduced sand body sample in subsequent steps, thereby determining whether the sandstone uranium deposit at that location is formed by exudation.

[0014] Oxidized sedimentary formations, also known as reddish-brown formations in this field, contain oxidized rock bodies such as red mudstone and oxidized sandstone. Reduced sand bodies, also known as gray sand bodies, can appear gray, dark gray, grayish-black, or black. Common reduced sand bodies include various types such as mudstone, carbonaceous mudstone, sandstone, and carbonaceous sandstone. Preferably, samples of each type of reduced sand body are collected during the sampling process to ensure the accuracy and comprehensiveness of the identification results. Those skilled in the art can determine the distribution of uranium-bearing reduced sand bodies in oxidized sedimentary formations and collect reduced sand body samples based on relevant geological data in the uranium exploration area, such as borehole data and geological profiles.

[0015] Understandably, in step S104, various tests may be required on the reduced sand sample to determine the type of organic matter in the reduced sand sample. These tests may require certain processing of the reduced sand sample, such as grinding it into powder, polishing it into thin sheets, or forming inclusion sheets. Therefore, during the collection of reduced sand samples, those skilled in the art can collect appropriate quantities and specifications of reduced sand samples according to the specific test items required.

[0016] In step S104, the type of organic matter in the collected reduced-color sand body sample is identified to determine the type of organic matter in the reduced-color sand body sample. The organic matter described in this application may include, but is not limited to, coal seams, coal lines, plant debris and remains, carbon debris, microorganisms, (geographic) bitumen, various organic acids, humus, and dispersed free or adsorbed hydrocarbons, oil and gas, and other organic substances.

[0017] Different methods can be used to determine different types of organic matter. Those skilled in the art can refer to relevant techniques in the field to determine the common types of organic matter in reduced colored sand bodies. The relevant sections below will also provide specific methods for determining several types of organic matter, which will not be elaborated here.

[0018] In step S106, if the type of organic matter determined in step S104 includes at least one of hydrocarbons, bitumen, and sapropelic kerogen, then it can be determined that the reduced-colored sand body sample contains organic matter originating from the strata beneath the oxidized-colored sedimentary formation. It should be noted that, in this application, determining the presence of organic matter originating from the strata beneath the oxidized-colored sedimentary formation in the reduced-colored sand body sample does not preclude the presence of organic matter from other sources.

[0019] As described above, in the theory of leaching mineralization, uranium in reduced-colored sand bodies is formed under the action of reducing fluids seeping from deep organic-rich strata. Here, "deep" generally refers to strata developed below oxidized sedimentary formations. If it is determined that there is organic matter from the strata below oxidized sedimentary formations in the reduced-colored sand body, it can be determined that the reduced-colored sand body has been acted upon by seeping reducing fluids, and thus the uranium deposit at that location can be determined to be an leaching sandstone uranium deposit.

[0020] Hydrocarbon organic matter can include gaseous hydrocarbons and liquid hydrocarbons. This application proposes that hydrocarbons in reduced-colored sand bodies usually originate from oil and gas-producing strata beneath oxidized-colored sedimentary formations, such as strata with developed source rocks beneath oxidized-colored sedimentary formations. Therefore, the presence of hydrocarbons as organic matter types in reduced-colored sand body samples can be used as evidence of the presence of organic matter originating from strata beneath oxidized-colored sedimentary formations in reduced-colored sand body samples.

[0021] Asphalt, also known as bitumen in the art, is proposed in this application to be a solid organic matter in the organic matter of the strata beneath the oxidized sedimentary formations, which is usually present in the interstitial material of the reduced sand body in the form of asphalt. Therefore, the type of organic matter in the reduced sand body sample, including asphalt, can be used as evidence of the presence of organic matter from the strata beneath the oxidized sedimentary formations in the reduced sand body sample.

[0022] Kerogen refers to dispersed organic matter in sedimentary rocks that is insoluble in alkalis, non-oxidizing acids, and non-polar organic solvents. The properties of kerogen formed from organic matter of different origins vary considerably. Kerogen is mainly classified into three types: Type I kerogen, also known as saprophytic kerogen, is predominantly composed of lipid compounds, with abundant straight-chain alkanes and few polycyclic aromatic hydrocarbons and oxygen-containing functional groups, characterized by high hydrogen and low oxygen content. Type II kerogen has a relatively high hydrogen content, but slightly lower than Type I kerogen. It has a highly saturated polycyclic carbon skeleton, containing a significant amount of medium-length straight-chain alkanes and cycloalkanes, as well as polycyclic aromatic hydrocarbons and heteroatom functional groups. Type III kerogen, also known as humic kerogen, is characterized by low hydrogen and high oxygen content, predominantly containing polycyclic aromatic hydrocarbons and oxygen-containing functional groups, with very few saturated hydrocarbons, and originates from higher terrestrial plants.

[0023] This application proposes that organic matter from strata beneath oxidized sedimentary formations typically forms saprophytic kerogen, while organic matter from syn-sedimentary formations typically forms humic kerogen. Therefore, the presence of saprophytic kerogen in reduced sand body samples can be used as evidence of the presence of organic matter from strata beneath oxidized sedimentary formations in reduced sand body samples.

[0024] The presence of the above types of organic matter can all serve as evidence that organic matter originates from the strata beneath the oxidized sedimentary formation in the reduced-color sand body sample. Therefore, if step S104 determines that the type of organic matter includes any of the above types, it can be determined that organic matter originating from the strata beneath the oxidized sedimentary formation exists in the gray sand body.

[0025] Furthermore, the above-mentioned types of organic matter can coexist in reduced-color sand bodies, and understandably, these types of organic matter exhibit multiple phases such as gas, liquid, and solid. If the above-mentioned types of organic matter are found simultaneously in a reduced-color sand body sample, the possibility of misjudgment will be greatly reduced. Therefore, those skilled in the art can also choose to make a judgment that the reduced-color sand body sample contains organic matter originating from the strata beneath the oxidized-color sedimentary formation only when multiple types of organic matter are found simultaneously, in order to improve the accuracy and reliability of the identification of the source of organic matter.

[0026] To improve identification efficiency, in some embodiments, step S104 may only identify the types of organic matter mentioned above. In other embodiments, step S104 may also identify organic matter more comprehensively than just the types mentioned above. If other types of organic matter are identified in addition to the types mentioned above, and these other types of organic matter indicate other sources of organic matter, further comprehensive analysis may be necessary to improve the accuracy of the identification results and avoid misjudgments.

[0027] The following describes several specific methods for determining the type of organic matter in reduced-color sand samples. Each of the following methods can determine at least one type of organic matter. Those skilled in the art can use the various methods described below individually or in combination according to actual needs.

[0028] In some embodiments, determining the type of organic matter in the reduced-color sand body sample in step S104 may include: observing the morphology of organic matter fragments in the reduced-color sand body sample under a microscope; performing laser Raman analysis on the observed organic matter fragments; if the organic matter fragments are vein-like, no plant cell cavity structure is observed in the organic matter fragments, and a double peak appears in the result of the laser Raman analysis, then the type of organic matter in the reduced-color sand body sample is determined to include asphalt.

[0029] Specifically, the collected reduced-color sand samples can first be prepared into thin sections. The specific method for preparing the thin sections can be performed by those skilled in the art according to relevant experimental standards, and there are no restrictions on this. Then, a polarizing microscope can be used to observe the morphology of organic matter fragments in the reduced-color sand samples. Organic matter fragments refer to organic matter in a fragmented state. When observing the morphology of organic matter fragments, it is necessary to pay attention to whether the organic matter fragments exhibit vein-like structures, flow structures, dry cracks, and plant cell lumen structures, etc.

[0030] Furthermore, laser Raman spectroscopy analysis can be performed on the observed organic matter debris. For example, organic matter debris that is vein-like, lacks plant cell cavities, and has dry cracks can be located and then subjected to laser Raman analysis. If the characteristic peak in the laser Raman analysis result of the organic matter debris is a double peak, it indicates that the organic matter debris is asphalt, and thus it can be determined that the type of organic matter in the reduced color sand sample includes asphalt.

[0031] Figure 2 A schematic diagram of laser Raman spectroscopy analysis results of organic matter debris in one embodiment is shown. The characteristic peak 21 shown in the figure has a typical bimodal structure, which can indicate that the organic matter is asphalt.

[0032] In addition to the methods described above, those skilled in the art may also choose other methods commonly used in the art to identify bitumen in reduced-color sand samples.

[0033] In some embodiments, determining the type of organic matter in a reduced sand body sample may further include: observing the reduced sand body sample under a fluorescence microscope, and if blue and / or yellow fluorescence appears in the reduced sand body sample, then determining that the type of organic matter in the reduced sand body includes hydrocarbons. Figure 3 A fluorescence microscope image of a reduced-color sand body sample from one embodiment is shown, revealing a region 31 emitting relatively strong blue fluorescence (the color is not shown in the image), indicating that the organic matter in the reduced-color sand body includes hydrocarbons.

[0034] Specifically, the reduced-color sand body sample can first be ground into inclusion slices. During mineral growth, gaseous and liquid phase substances brought by the ore-forming fluid will exist in the form of inclusions. Therefore, in this embodiment, the reduced-color sand body sample is ground into inclusion slices, and then the inclusions are observed using a fluorescence microscope to determine whether they contain hydrocarbons. Similarly, those skilled in the art can grind inclusion slices according to relevant testing standards. As an example, the thickness of the inclusion slices can be approximately 70-80 μm, and 502 glue can be injected.

[0035] Under a fluorescence microscope, the main observable components are liquid hydrocarbons in the inclusions. These liquid hydrocarbons will emit blue or yellow fluorescence. Therefore, if blue and / or yellow fluorescence is observed, it can be determined that the organic matter in the reduced sand sample includes hydrocarbons.

[0036] This application also proposes that hydrocarbon inclusions are typically developed in structures such as carbonate cements, quartz enlarged edges, and secondary fractures. Therefore, in some embodiments, reduced-color sand samples including the above-mentioned structures can be selected to grind inclusion sheets, and the inclusions developed in the above-mentioned structures are mainly observed to improve efficiency.

[0037] In some embodiments, determining the type of organic matter in a reduced-color sand body sample may further include: performing acid hydrolysis hydrocarbon analysis on the reduced-color sand body sample to determine that the type of organic matter in the reduced-color sand body sample includes hydrocarbons.

[0038] Acid hydrolysis analysis is a commonly used method in this field for analyzing hydrocarbons in sediments. It releases gaseous hydrocarbons and tests their gaseous component content. As an example, in acid hydrolysis analysis, hydrochloric acid is used to decompose carbonate minerals in a reduced-color sand body sample, releasing gaseous substances. Then, an alkaline solution is used to remove carbon dioxide from the gaseous substances. Finally, the collected gaseous substances are tested for hydrocarbon gas content to determine the presence of gaseous hydrocarbons.

[0039] In some embodiments, the gaseous hydrocarbons mentioned herein may include methane. In some other embodiments, the gaseous hydrocarbons mentioned herein may specifically refer to hydrocarbons of oil and gas origin. The presence of hydrocarbons of oil and gas origin can be determined by plotting the combination parameters of methane and other alkane content.

[0040] Figure 4 A schematic diagram of the acid hydrolysis hydrocarbon analysis results of one embodiment is shown, where the horizontal axis represents the ratio between the contents of methane and ethane and other alkanes, and the vertical axis represents the ratio of methane content to total alkanes content. The diagram shows oil-type gas region 41, mixed gas region 42, coalbed methane region 43, and biogas region 44. These regions can be divided by those skilled in the art based on the component characteristics of the relevant types of gaseous hydrocarbons, and will not be elaborated further here. It can be seen that the plotted points are mainly distributed in oil-type gas region 41, therefore it is considered that gaseous hydrocarbons are present in the reduced-color sand body sample, and that these gaseous hydrocarbons are of oil-type origin.

[0041] In some embodiments, determining the type of organic matter in a reduced-color sand body sample may further include: performing rock pyrolysis analysis on the reduced-color sand body sample to determine that the type of organic matter in the reduced-color sand body sample includes saprophytic kerogen.

[0042] There are various methods in the art for determining kerogen type, such as determination based on microscopic features, determination based on elemental composition, determination based on biological origin, etc. In this embodiment, rock pyrolysis is used to determine the type of kerogen, thereby determining that the type of organic matter in the reduced-color sand body sample includes saprophytic kerogen. Saprophytic kerogen here generally refers to the type I kerogen described above. In some embodiments, saprophytic kerogen here may also include humic saprophytic (Type II1) kerogen.

[0043] Rock pyrolysis can be performed according to relevant standards in this field. For example, during rock pyrolysis, the detection conditions can be set as follows: high-purity helium pressure: 0.20–0.30 MPa, air pressure: 0.30–0.40 MPa, and hydrogen pressure: 0.20–0.30 MPa. Rock pyrolysis can detect, but is not limited to, total organic carbon (TOC) and hydrogen index (I). H ), oxygen index (I) O With multiple data sources, such as rock pyrolysis data, those skilled in the art can analyze the data obtained from rock pyrolysis according to relevant standards to distinguish the specific type of kerogen in the reduced-color sand body sample.

[0044] In some other embodiments, those skilled in the art may also use other suitable methods to determine the type of kerogen, such as using a microscope, fluorescence microscope, scanning electron microscope, etc., to determine the microscopic composition of kerogen and thus determine its type. Another example is using infrared spectroscopy to determine the functional group composition of kerogen and thus determine its type.

[0045] Furthermore, this application proposes that, in addition to determining the source based on the type of kerogen, the source can also be determined by the maturity of the kerogen to improve accuracy. Specifically, if the organic matter type includes saprophytic kerogen, and the maturity of the saprophytic kerogen is higher than a preset value, then the presence of organic matter in the reduced-color sand body sample is determined to originate from the organic matter of the strata beneath the oxidized-color sedimentary formation.

[0046] In this field, kerogen maturity is typically categorized from low to high as immature, mature, highly mature, and overmature. For example, if the maturity of saprophytic kerogen is mature or higher, it indicates the presence of organic matter from the strata beneath the oxidized sedimentary formation in the reduced-color sand body sample. Those skilled in the art can reasonably set preset maturity values ​​based on the actual situation and the method used to determine kerogen maturity.

[0047] In some embodiments, the maturity of kerogen can be determined based on the results of rock pyrolysis, thereby eliminating the need for additional experiments, improving efficiency, and reducing costs. In some other embodiments, those skilled in the art can also choose other suitable methods to determine the maturity of kerogen, such as measuring carbon isotope composition, functional group composition, microstructure, thermal weight loss, vitrinite reflectance, etc.

[0048] This application also proposes that, in addition to identifying the source of organic matter based on the above-mentioned types of organic matter, the source of organic matter can be further identified by the composition of organic matter. The reducing fluids that seep from the strata below the oxidized sedimentary formations usually contain lower aquatic organisms, such as algae, and the n-alkanes from these lower aquatic organisms usually exhibit the characteristic of a low carbon number main peak.

[0049] Therefore, in some embodiments, gas chromatography can be further used to determine the number of n-alkane carbons in the soluble organic matter in the reduced-color sand body sample, if the type of organic matter in the reduced-color sand body sample includes at least one of hydrocarbons, bituminous asphalt, and saprophytic kerogen, and the number of n-alkane carbons of the soluble organic matter is distributed in the C... 15 ~C 22 Between these conditions, it is determined that the reduced-color sand body sample contains organic matter originating from the strata beneath the oxidized-color sedimentary formation.

[0050] Figure 5 A schematic diagram of the gas chromatography analysis results of saturated hydrocarbons in one embodiment is shown. It can be seen that the carbon peak in the concentrated carbon peak distribution region 51 is C. 15 ~C 22 Therefore, it can be determined that the reduced-color sand body sample contains organic matter originating from the strata beneath the oxidized-color sedimentary formation.

[0051] Soluble organic matter refers to organic substances in rocks that can dissolve in organic solvents, such as the bitumen mentioned above. Soluble organic matter can be extracted from reduced-color sand samples using organic solvents such as chloroform, dichloromethane, benzene, methanol, and acetone. Then, gas chromatography analysis of the saturated hydrocarbons can be performed to determine the number of n-alkane carbons. If the main carbon peak in the saturated hydrocarbon gas chromatography analysis is located at C... 15 ~C 22 The presence of these values ​​indicates that the saturated hydrocarbons in the soluble organic matter originate from lower aquatic organisms, and thus can indicate the presence of organic matter in the reduced-color sand body sample originating from the strata beneath the oxidized-color sedimentary formation.

[0052] In some embodiments, step S102 may specifically include: determining the distribution range of uranium-containing reduced-color sand bodies in the oxide-color deposition construction; selecting multiple points within the distribution range of uranium-containing reduced-color sand bodies for sampling to obtain reduced-color sand body samples.

[0053] Specifically, those skilled in the art can first determine the distribution range of uranium-bearing reduced-color sand bodies in oxidized-color sedimentary formations based on geological data of the uranium deposit exploration area. Then, multiple different locations within this distribution range can be selected for sample collection, thereby ensuring sample diversity and comprehensive coverage, and thus improving the accuracy of the identification results.

[0054] In some embodiments, when sampling at multiple locations, relatively dark-colored reduced sand bodies can be collected as reduced sand body samples. The darker the color of the reduced sand body sample, the more organic matter it contains. Therefore, collecting relatively dark-colored reduced sand bodies facilitates subsequent analysis to determine the type of organic matter in them.

[0055] In some embodiments, a hydrocarbon-bearing source rock stratum is developed beneath the oxidized sedimentary formation described in step S102. If the type of organic matter in the reduced-color sand body sample is determined in step S104 to include at least one of hydrocarbons, geoasphalt, and saprophytic kerogen, then in step S106, it can be determined that organic matter originating from the hydrocarbon-bearing source rock stratum is present in the reduced-color sand body sample.

[0056] As described above, in the theory of seepage mineralization, the reducing fluids seeping from deep strata usually originate from deep organic-rich strata. Among them, the most common strata capable of seeping reducing fluids are strata containing source rocks. Here, source rock strata refer to strata with source rock formations.

[0057] Based on this, in this embodiment, the source of organic matter in the reduced-colored sand body in the oxidized colored sedimentary formation with hydrocarbon source rock strata below can be identified. That is, in the process of collecting samples in step S102, the distribution range of the oxidized colored sedimentary formation with hydrocarbon source rock strata below is first delineated, and then the reduced-colored sand body samples are collected, thereby improving the efficiency of identification.

[0058] The following example, using the identification of the organic matter source in the reduced-color sand bodies of the Hadatu uranium deposit in the Yierlian Basin, will be used to provide a more detailed description and supplement to the methods in one or more embodiments mentioned above.

[0059] In the Hadatu uranium deposit in the Erlian Basin, there are uranium-bearing reduced-color sand bodies distributed in the oxidized sedimentary formations. The source rock formations developed in the Arshan Formation and Tengger Formation below the oxidized sedimentary formations are hydrocarbon-bearing strata.

[0060] Through field surveys and the compilation of petrogeochemical maps, the distribution range of reduced-colored sand bodies within the oxidized sedimentary formations of the Hadatu uranium deposit in the Erlian Basin was determined, as well as the spatial relationship between the reduced-colored sand bodies and the oxidized sedimentary formations. The petrogeochemical maps compiled here mainly consist of borehole columnar sections and cross-sections. Subsequently, reduced-colored sand body samples were collected from multiple locations within the determined distribution range of the reduced-colored sand bodies. The collected samples included reduced-colored sand bodies such as mudstone, sandstone, carbonaceous sandstone, and carbonaceous mudstone.

[0061] Furthermore, the collected reduced-color sand samples were subjected to microscopic observation, fluorescence microscopy, laser Raman analysis, acid hydrolysis hydrocarbon analysis, rock pyrolysis, and saturated hydrocarbon gas chromatography analysis.

[0062] Specifically, during microscopic observation, the reduced-color sand sample was ground into a thin section and observed under a polarizing microscope to determine the microscopic morphology of the organic matter debris, including whether it was vein-like, had a flow structure, and possessed plant cell lumen structures. Subsequently, laser Raman analysis was performed on the observed organic matter debris to observe whether its characteristic peaks were similar to the bimodal peaks of bitumen.

[0063] In this embodiment, the organic matter debris was found to be vein-like under a polarizing microscope, and no plant cell lumen structure was observed. Laser Raman analysis showed that its characteristic peaks were bimodal peaks of asphalt. Based on this, it was determined that the type of organic matter in the reduced-color sand sample included asphalt.

[0064] During fluorescence microscopy observation, the reduced-color sandstone samples were first ground into inclusion sections, which were then coated with 502 glue to a thickness of approximately 70–80 μm. Under the fluorescence microscope, blue fluorescent liquid hydrocarbons were observed filling the sandstone interstitial material within the inclusion sections. Fluorescent liquid hydrocarbon inclusions were also found in the secondary fractures of quartz and the calcite cement. Based on this, it was determined that the organic matter in the reduced-color sandstone samples included liquid hydrocarbons.

[0065] In the acid hydrolysis hydrocarbon analysis, the collected reduced-color sand body sample was first dried, then crushed in a mortar, sieved (40 mesh), and mixed thoroughly. 50g of the treated sample was weighed and placed in a flask, and hydrochloric acid was added to decompose the carbonate minerals in the sample. The released gas was then passed through an alkaline solution apparatus to remove carbon dioxide (CO2). After acid hydrolysis was complete in the flask (no more bubbling), a certain amount of gas was extracted using a microsyringe for hydrocarbon component content testing. Finally, based on the analysis results, it was determined that the organic matter in the reduced-color sand body sample included gaseous hydrocarbons.

[0066] The rock pyrolysis was performed using an OGE-II oil and gas evaluation instrument, following the GB / T18602-2012 standard for rock pyrolysis analysis. The testing conditions were: high-purity helium pressure: 0.20–0.30 MPa, air pressure: 0.30–0.40 MPa, and hydrogen pressure: 0.20–0.30 MPa. The results showed that the organic matter in the reduced-color sandstone samples included sapropel-type kerogen, and its maturity level was mature to over-mature.

[0067] When performing gas chromatography analysis of saturated hydrocarbons, the main carbon peaks of n-alkanes obtained are mostly C16, indicating that the saturated hydrocarbons come from lower aquatic organisms, and thus indicating that the reduced-color sand body sample contains organic matter from the hydrocarbon-bearing source rock strata beneath the oxidized-color sedimentary formation.

[0068] Based on the above results, it was finally determined that the reduced-color sandstone bodies of the Hadatu uranium deposit in the Erlian Basin contain organic matter from the source rocks of the Arshan Formation and Tengger Formation beneath the red-colored formation.

[0069] The present invention has been described in detail above with reference to the accompanying drawings and embodiments. However, the present invention is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the spirit of the present invention. All contents not described in detail in the present invention can be derived from existing technologies.

Claims

1. A method for identifying the source of organic matter in reduced-color sand bodies of sandstone uranium deposits, comprising: Collect uranium-containing reduced-color sand samples from oxide-colored sedimentary formations; The type of organic matter in the reduced-color sand body sample is determined, wherein rock pyrolysis analysis is performed on the reduced-color sand body sample to determine whether the type of organic matter in the reduced-color sand body sample includes saprophytic kerogen; After determining that the organic matter in the reduced-color sand body sample includes saprophytic kerogen, the maturity of the saprophytic kerogen is determined based on the results of the rock pyrolysis analysis. The number of n-alkane carbons in the soluble organic matter in the reduced-color sand sample was determined by gas chromatography. Identify the source of organic matter in the reduced-color sand body sample, wherein if the reduced-color sand body sample includes saprophytic kerogen and the maturity of the saprophytic kerogen is higher than a preset value, and the n-alkyl carbon number distribution of the soluble organic matter is in the C... 15 ~C 22 Between these conditions, it is determined that the reduced-color sand body sample contains organic matter originating from the hydrocarbon-bearing source rock strata developed beneath the oxidized-color sedimentary formation.

2. The method according to claim 1, wherein, The collected samples of uranium-bearing reduced-color sand bodies from the oxide-colored depositional formations include: Determine the distribution range of uranium-containing reduced-color sand bodies in the aforementioned oxide-colored depositional formation; Multiple sampling points were selected within the distribution range of the uranium-containing reduced chromogenic sand bodies to obtain samples of the reduced chromogenic sand bodies.

3. The method according to claim 1 or 2, wherein, The reduced-color sandstone sample includes at least one of mudstone, carbonaceous mudstone, sandstone, and carbonaceous sandstone.

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