WO2023004530A1

WO2023004530A1 - Method for locating sandstone-type uranium deposits in red variegated layer in a sedimentary basin

Info

Publication number: WO2023004530A1
Application number: PCT/CN2021/108356
Authority: WO
Inventors: 李子颖; 刘武生; 吴曲波; 李西得; 纪宏伟; 刘持恒; 史清平; 邱林飞; 李伟涛
Original assignee: 核工业北京地质研究院
Priority date: 2021-07-26
Filing date: 2021-07-26
Publication date: 2023-02-02

Abstract

A method for locating sandstone-type uranium ore in a red variegated layer of a sedimentary basin, comprising: determining a red variegated layer in a sedimentary basin, the red variegated layer being an oxidative stratum developed above a reductive stratum; determining a fluvial facies region in the red variegated layer; according to geological information of the fluvial facies region, determining a plurality of grey sand body development regions in the fluvial facies region; and carrying out borehole sampling analysis on the plurality of grey sand body development regions, and delineating a uranium ore distribution region in the grey sand body development regions according to the borehole sampling analysis result. The method for locating uranium ore in the red variegated layer of the sedimentary basin may quickly and accurately locate uranium ore in the red variegated layer of the sedimentary basin.

Description

Location method of sandstone-type uranium deposits in red variegated layers of sedimentary basins

technical field

Embodiments of the present invention relate to the technical field of geological information, and in particular to a method for locating sandstone-type uranium deposits in red variegated layers in sedimentary basins.

Background technique

Basin refers to a unified subsidence unit with the same or similar development characteristics (including sedimentary characteristics, stress environment, development time and process) on the crust. When sediments of considerable thickness are developed in the unit and the center is thick and the edges are thin to none, it is called sedimentary basin. In recent years, sandstone-type uranium deposits have been found in many red-variegated sedimentary basins. However, the occurrence environment and characteristics of sandstone-type uranium deposits in sedimentary basins are completely different from those of interlayer oxidation zone or phreatic oxidation zone type. It is difficult to find the uranium ore by using the traditional interlayer oxidation zone type or submerged oxidation zone type uranium ore prospecting method, and it is easy to cause ore leakage and missing ore.

Contents of the invention

In view of the above problems, the present invention is proposed to provide a method for locating sandstone-type uranium deposits in red variegated layers in sedimentary basins that overcomes the above problems or at least partially solves the above problems.

According to an embodiment of the present invention, a method for locating sandstone-type uranium deposits in a red variegated layer in a sedimentary basin is provided, including: determining the red variegated layer in a sedimentary basin, and the red variegated layer is developed above a reducing stratum Oxidizing strata; determining the fluvial facies area in the red variegated layer; determining multiple gray sand body development areas in the fluvial facies area according to the geological information of the fluvial facies area; for multiple gray sand bodies The borehole sampling analysis is carried out in the development area, and the uranium ore distribution area is delineated in the gray sand body development area according to the results of the borehole sampling analysis.

The method for locating uranium deposits in the red variegated layer of a sedimentary basin according to an embodiment of the present invention can quickly and accurately locate uranium deposits in the red variegated layer of a sedimentary basin.

Description of drawings

Fig. 1 is a flow chart of a method for locating sandstone-type uranium deposits in a red variegated layer in a sedimentary basin according to an embodiment of the present invention;

Fig. 2 is a flow chart of determining the gray sand body development area according to an embodiment of the present invention;

Fig. 3 is a flow chart of delineating the distribution area of uranium deposits through drilling analysis according to an embodiment of the present invention;

FIG. 4 is a flowchart of determining a sampling object according to an embodiment of the present invention;

Fig. 5 is a schematic diagram of the delineated gray sand body development area and uranium ore distribution area according to the embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Apparently, the described embodiment is one embodiment of the present invention, but not all of them. Based on the described embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the present invention shall have the usual meanings understood by those skilled in the art to which the present invention belongs. If the descriptions such as "first" and "second" are involved in the whole text, the descriptions such as "first" and "second" are only used to distinguish similar objects, and cannot be understood as indicating or implying their relative importance, sequence, etc. The order or the number of technical features indicated by implicit indication should be understood as "first", "second" and other described data can be interchanged under appropriate circumstances. If "and/or" appears throughout the text, it means to include three parallel plans, taking "A and/or B" as an example, including plan A, or plan B, or a plan that satisfies both A and B. In addition, for ease of description, spatially relative terms, such as "above", "below", "top", "bottom", etc., may be used herein to describe only one device or feature as shown in the figures in relation to other devices or features. The spatial relationship of features should be understood to also encompass different orientations in use or operation than those shown in the figures.

According to an embodiment of the present invention, a method for locating a sandstone-type uranium deposit in a red variegated layer in a sedimentary basin is provided, referring to FIG. 1 , including:

Step S102: Determine the red variegated layer in the sedimentary basin, the red variegated layer is an oxidative stratum developed above the reducing stratum;

Step S104: determining the fluvial facies area in the red variegated layer;

Step S106: Determine multiple gray sand body development areas in the fluvial facies area according to the geological information of the fluvial facies area;

Step S108: Conduct borehole sampling analysis on multiple gray sand body development areas, and delineate uranium ore distribution areas in the gray sand body development areas according to the drill hole sampling analysis results.

In step S102, the sedimentary basin is a basin with relatively thick sediments, thick center, and thin to no edge, which adopts the general definition method in the field, and those skilled in the art can determine the scope of the sedimentary basin by consulting geological data, etc. . The red variegated layer refers to the oxidized stratum developed above the reducing strata in the sedimentary basin. The reducing stratum can be the stratum developing reducing rock series such as gray and gray-green formations, such as oil and gas producing layers, coal-bearing rock series, etc. etc., the oxidative formation usually presents red variegated layer, so it is called red variegated layer in the present invention. Similarly, the determination of the red variegated layer can be completed by consulting geological data. For example, in a selected sedimentary basin, the stratum development of the sedimentary basin can be obtained by consulting the geological data to find the red layer in the sedimentary basin. Motley layer. Of course, those skilled in the art can also use field survey methods such as drilling to determine the development of the strata in the sedimentary basin when relevant geological data cannot be consulted, and then determine the red variegated layer. In a specific embodiment, the inventors of the present invention conducted field surveys in the Qiha Rigetu Sag in the Erlian Basin. The lower part of the Sag is the Arshan Formation and the Tengger Formation, which are mainly gray and gray-green structures. Oil and gas source rocks are also oil and gas reservoirs; the upper member of the overlying Saihan Formation is a set of oxidized red variegated fluvial sedimentary structures, that is, red variegated layers, which will be described in the relevant part below.

In step S104, the fluvial facies area in the red variegated layer is determined, and the fluvial facies area refers to the sedimentary facies formed by a set of sediments or sedimentary rocks deposited by onshore rivers or other runoffs, also using the general definition method in this field , it can be understood that sandstone-type uranium deposits are distributed in sand bodies, and the fluvial facies area is actually an area that is conducive to the distribution of sand bodies in the sedimentary basin. fluvial facies area. Those skilled in the art can also determine the fluvial facies area in the uranium-producing oxidizing formation by consulting existing geological data or on-site investigation, and details will not be repeated here.

In step S106, a plurality of gray sand body development areas in the fluvial facies region are determined according to the geological information of the fluvial facies region. After determining the fluvial facies area, those skilled in the art can further look for the gray sand body development area in it according to the geological information of the fluvial facies area. The gray sand body is reductive, so the gray sand body developed in the red variegated layer The possibility of forming uranium ore is higher. The geological information of the fluvial facies area can refer to the fluvial facies area, such as sand body distribution data, stratum development, channel profile, channel basement depth and any other information that can be used to judge whether there is gray sand body distribution, Those skilled in the art can obtain the above-mentioned geological information by consulting existing geological data, and can also obtain the above-mentioned geological information through on-site survey means, such as seismic analysis, drilling analysis, etc., without specific limitations.

In some embodiments, a method for quickly determining the gray sand body development area is also provided. Specifically, when determining multiple gray sand body development areas in the fluvial facies area based on the geological information of the fluvial facies area, firstly, according to the The channel profile and basement depth of the fluvial facies area are determined based on the geological information of the facies area, and the gray sand body development area is determined according to the channel profile and basement depth.

In some embodiments, referring to Fig. 2, determining the gray sand body development area according to the channel profile and the buried depth of the basement may specifically include:

Step S202: Determine the area where the channel profile changes in the fluvial facies area as a candidate area;

Step S204: Determine the gray sand body development area according to the basement depth and structural development of the candidate area.

It is understandable that the formation of sand bodies is usually related to the erosion of rivers, so the area where the channel profile changes is the area where sand bodies are enriched in the fluvial facies area, and gray sand bodies are more likely to develop in this area, which is gray Sand bodies are favorable development areas, so in this embodiment, the scope is first narrowed down to such candidate areas. In some embodiments, the region where the channel profile changes may include at least one of the following: a region where the channel extension direction changes, a channel intersection region, a channel width changes region, and a region where fracture structures appear in the channel. Of course, those skilled in the art can also analyze the channel profile of the fluvial facies area according to the actual situation, for example, combining the structural development of the fluvial facies area (such as fault structures) to screen out the areas that are conducive to the development of gray sand bodies as candidates area.

Further, in step S204, the gray sand body development area is determined according to the basement depth of the candidate area. The inventors of the present invention propose that in the fluvial facies area, the gray sand body usually presents a sedimentary distribution, so the gray sand body development area The area usually appears in the depression area of the basement, so the gray sand body development area can be further delineated according to the change of basement depth in the candidate area.

Specifically, in some embodiments, when determining the gray sand body development area according to the basement depth of the candidate area, the gray sand body development area may meet the following conditions: the base buried depth in the middle of the gray sand body development area is smaller than the basement depth on both sides Buried deep. That is, the gray sand body development area is the area where the channel basement is depressed in the candidate area. For example, the basement of the gray sand body development area may present a "V" or "U" shape. In some embodiments, if multiple depressions are connected If a "W" shape is formed, it can also be delineated as a gray sand body development area. In some embodiments, the area where the basement depth in the middle is smaller than the basement depth on both sides and the difference is greater than the preset value can be further selected as the gray sand body development area. It can be understood that there are usually many small depressions in the channel basement, If every small sag is delineated as a gray sand body development area, the workload will be greatly increased. Therefore, by adding the above restrictions, larger sags can be selected as gray sand body development areas. Technicians can also delineate suitable gray sand body development areas in other ways, such as combining structural development conditions (such as sand body development) in the candidate area, so that the scope of each gray sand body development area will not be too small.

The above examples describe a variety of methods to delineate the gray sand body development area, but it is understandable that those skilled in the art can use the combination of one or more of the above methods, and can also use other suitable methods to delineate the red variegated In the gray sand body development area in the layer, it is only necessary to limit the operation range in the subsequent steps to the area with more gray sand body development as much as possible.

After delineating a plurality of gray sand body development areas in step S106, in step S108, carry out borehole sampling analysis to a plurality of gray sand body development areas, according to the results of borehole sampling analysis to identify the gray sand body development areas in a plurality of gray sand body development areas. Delineate the distribution area of uranium deposits. Drillhole sampling analysis is mainly to verify whether the gray sand body in the delineated gray sand body development area is uranium ore. Those skilled in the art can drill holes in the delineated gray sand body development area to obtain multiple samples, and Use appropriate technical means to analyze whether the sample is uranium ore-producing sand body, so as to further determine the distribution area of uranium ore in the gray sand body development area according to the analysis results of the sample.

It is understandable that the more sampling locations, the more accurate the final delineated uranium distribution area will be. However, too many sampling locations will face the problem of high detection costs. In order to delineate the uranium distribution area as accurately as possible At the same time, the cost is reduced. In some embodiments, referring to FIG. 3 , performing borehole sampling analysis on multiple gray sand body development areas may specifically include:

Step S302: Borehole analysis is carried out in each gray sand body development area to determine the sampling object;

Step S304: Obtain multiple samples of the sampling object for elemental analysis, and delineate the uranium distribution area according to the elemental analysis results.

In this embodiment, firstly, borehole analysis is carried out on each gray sand body development area to determine the sampling object, and then multiple samples are obtained for the determined sampling object for elemental analysis, and the uranium distribution area is delineated according to the results of the elemental analysis . Borehole analysis to determine the sampling objects is actually to screen out the objects (regions) that are most likely to develop uranium deposits in the gray sand body distribution area through drilling, and then further sample and analyze these sampling objects to determine whether they form uranium deposits. mine, avoiding intensive sampling of the entire gray sand body development area.

In some embodiments, referring to FIG. 4 , performing borehole analysis in each gray sand body development area in step S302 to determine sampling objects may include:

Step S402: setting multiple drilling points in each gray sand body development area;

Step S404: Drilling the drilling points to obtain the gray sand rate of each drilling point, the gray sand rate is the ratio of the thickness of the gray sand body to the total thickness of the sand body in the red variegated layer at the drilling point;

Step S406: Determine the gray sand body in the area where the drilling point with the lime-sand ratio of 0.2-0.7 is located as the sampling object.

Specifically, Fig. 5 shows a plurality of gray sand body development areas 51 determined in a certain fluvial facies area, where the arrows point to the flow direction in the channel, and in the gray sand body development areas 51, multiple Drilling points 52, for example, a plurality of drilling points 52 can be arranged along the long axis of the gray sand body development area 51, and in some specific embodiments, the spacing of the plurality of drilling points 52 can be 800-3600 meters, 3-5 drilling points 52 can be set in each gray sand body development area 51 .

In step S404, it is necessary to obtain the lime-sand rate at each drilling point 52. Specifically, after drilling the drilling point, the geological sample at the drilling point can be extracted, and the geological sample can be used to measure the The thickness of the gray sand body and the total thickness of the sand body in the red variegated layer at the drilling point, the gray sand body in the geological sample can be determined by visually identifying the color of the sand body, and those skilled in the art can also assist through simple chemical analysis The gray sand body is determined, and the total thickness of the sand body refers to the total thickness of all sand bodies including the gray sand body. In the embodiment of the present invention, the gray sand body ratio is defined as the ratio of the thickness of the gray sand body to the total thickness of the sand body.

In step S406, the gray sand body in the area where the drilling point 52 with the lime-sand ratio 0.2-0.7 is located is determined as the sampling object. Specifically, the contour map of the lime-sand rate can be drawn according to the change of the lime-sand rate at the drilling point 52. For example, as shown in FIG. 5, the gray-sand rate in the gray sand body development area 51 is deeper Larger and lighter in color, the gray-sand body in the area with a gray-sand ratio in the range of 0.2-0.7 is taken as the sampling object, so that in the subsequent relevant steps, the gray sand bodies can be collected for such sampling objects. Multiple samples are used for elemental analysis, so as to finally determine the uranium ore distribution area, such as the uranium ore distribution area 53 represented by the grid-shaped area in FIG. 5 .

It can be understood that, in addition to the above method of determining the sampling object by using the lime-sand ratio as a reference standard, those skilled in the art may also select other reference indicators to determine the sampling object, which is not specifically limited.

In some embodiments, after the sampling object is determined, multiple sampling points may be further set in the sampling object to obtain multiple samples, specifically, one sampling point may be set at an interval of 0.5 m for sampling. Different from the drilling in step S402, the amount of sample required for sampling the sampling object is relatively small. In some embodiments, only 400g of sample can be taken at each sampling point, so compared with the sample size in step S402 For drilling, the cost of sampling is low, so the sampling objects can be sampled more densely.

In some embodiments, elemental analysis can be performed on the sample obtained by sampling to determine whether it is uranium ore. If the result of elemental analysis meets the expected value, the sampling point is determined as the uranium ore target area, thereby, according to the uranium ore target The distribution of uranium deposits is used to delineate the distribution area of uranium deposits, that is, the distribution of uranium deposits is actually a collection of uranium deposit target areas. In some embodiments, when the uranium ore distribution area 53 is delineated according to the distribution of the uranium ore target area, the uranium ore distribution area 53 can be made to include the uranium ore target area and be in the shape of an island or a cluster. Understandably, sampling and element The obtained uranium ore target area may not be continuously distributed, and if the uranium ore distribution area 53 is delineated strictly according to the distribution of the uranium ore target area, the delineated uranium ore distribution area 53 may be scattered, which is not conducive to the layout of subsequent mining Therefore, in this embodiment, the uranium ore distribution area 53 is delineated in an island shape or a lobe shape, and it may also include some sampling points that have not been determined as the uranium ore target area under the premise of including the uranium ore target area. Those skilled in the art can delineate according to the actual distribution of uranium ore target areas, so that the uranium ore distribution area 53 is suitable for mining and the distribution of uranium ore target areas is relatively dense.

In some embodiments, the elemental analysis may specifically include at least one of the following: determining the content of uranium in the sample, determining the content of organic carbon in the sample, determining the content of acidolysis hydrocarbons in the sample, determining the correlation between uranium and FeO in the sample , Determine the correlation of uranium with cobalt, nickel, molybdenum, zinc in the sample.

In the above elemental analysis items, cobalt and nickel are deep source basic elements, while molybdenum and zinc are chalcophilic elements. The inventor of the present invention proposes that if uranium in the sample shows a significant positive correlation with these elements, then it can be It was identified as a uranium mine target area.

In some embodiments, the expected values of the elemental analysis results include at least one of the following: uranium content > 12×10 ^-6 (more than 3 times the background value of normal sandstone), organic carbon content > 0.25%, acidolysis hydrocarbon content > 450 μL·kg ^{- 1.} The correlation between uranium and FeO is >0.5, and there is a positive correlation between uranium and deep-source basic elements cobalt, nickel, and chalcophile elements molybdenum and zinc.

It can be understood that those skilled in the art can also use other elemental analysis means to assist in determining whether the sampling point is a uranium ore target area, which is not specifically limited.

Part of the embodiments mentioned above will be described in more detail with a specific embodiment below.

Taking the Qiharigetu section of the Erlian Basin as an example, the identification of sandstone-type uranium mineralization in the red variegated layer in the upper part of the Saihan Formation is carried out. The specific steps are as follows:

In this example, the inventor identified the upper part of the Saihan Formation in the Qiharigetu Sag as the red variegated layer in the sedimentary basin. Specifically, through the collection of geological data, the inventor learned that the lower layer of the Qiharigetu Sag in the Erlian Basin The Wei'ershan Formation and Tengger Formation are mainly gray and gray-green formations, which are not only oil and gas source rocks, but also oil and gas reservoirs; the upper part of the overlying Saihan Formation is a set of oxide red variegated fluvial facies sedimentary formations.

Further, in this example, the geological data of the fluvial facies in the upper section of the Qiharigetu Saihan Formation were collected, and it is known that (1) the red variegated layer in the upper section of the Saihan Formation in the Qiharigetu Sag generally develops from south to north with a width of 10-20km , 60km long ancient river channel; (2) Two tributaries develop from west to north and one tributary develops from east to north in the area. Then identify the changes in paleo-channel hydrology in the upper section of the Saihan Formation in the Qiharigetu red variegated layer (river confluence, turning, widening, narrowing, and deep faults), that is, the central and northern part of the Qiharigetu Sag, and determine it as a candidate area.

Furthermore, according to the basement information of the Qiharigetu sag, the sag is distributed in the SSW-NNE direction, with a width of 20-30 km and a length of 60 km. The location is regarded as the gray sand body development area, specifically, three gray sand body development areas of QH, QNG, and HDT are determined (refer to Figure 5).

Further, for the three gray sand body development areas of QH, QNG, and HDT, 3 to 5 borehole sampling analyzes were carried out at intervals of 2400-6600 meters in each area, and the total thickness and Gray sand body thickness, for the gray sand body whose gray sand body thickness/total sand body thickness is in the range of 0.2-0.7, a mixed sample is taken every 0.5m for major, trace and acidolysis hydrocarbon analysis and organic carbon content analysis. The obtained data were analyzed, among which, the content of uranium > 15×10 ^-6 , the content of organic carbon > 0.27%, the content of acidolysis hydrocarbons > 460μL·kg ^-1 , and the content of uranium and deep-source basic elements Co, Ni and chalophile elements Mo, The sampling points with obvious positive correlation with Zn are identified as the uranium ore target area. Among them, the specific values of the correlation between uranium and deep-source basic elements Co, Ni and chalcophile elements Mo, Zn can be found in the following table:

According to the results of elemental analysis, the inventor further delineated the distribution area of uranium deposits in the three regions of QH, QNG and HDT. At present, in the delineated uranium ore distribution area, a super-large sandstone uranium deposit, a uranium ore producing area, and a prospecting target area have been confirmed, with an effective rate of 75%.

The present invention has been described in detail above in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the above-mentioned embodiments, within the scope of knowledge possessed by those of ordinary skill in the art, some modifications can be made without departing from the spirit of the present invention. Variety. The content that does not describe in detail in the present invention all can adopt prior art.

Claims

A method for locating sandstone-type uranium deposits in red variegated layers in sedimentary basins, comprising:

Determining red variegated layers in sedimentary basins, said red variegated layers being oxidative strata that develop over reductive strata;

Determining fluvial facies regions in the red variegated layer;

determining a plurality of gray sand body development areas in the fluvial facies area according to the geological information of the fluvial facies area;

Borehole sampling analysis is carried out on multiple gray sand body development areas, and uranium ore distribution areas are delineated in the gray sand body development areas according to the results of the borehole sampling analysis.
The method according to claim 1, wherein said determining a plurality of gray sand body development areas in the fluvial facies area according to the geological information of the fluvial facies area comprises:

Determine the channel profile, basement depth and structural development of the fluvial facies area according to the geological information of the fluvial facies area, and determine the gray sand body development area according to the channel profile, basement depth and structural development .
The method according to claim 2, wherein determining the gray sand body development area according to the channel profile, the buried depth of the basement and the structural development includes:

Determining the area where the channel profile changes in the fluvial facies area as a candidate area;

The gray sand body development area is determined according to the basement depth and structural development of the candidate area.
The method according to claim 3, wherein the area where the channel profile changes includes at least one of the following:

Areas where the direction of channel extension changes, areas where channels converge, areas where channel width changes, and areas where fault structures appear in the channel.
The method according to claim 3 or 4, wherein, when determining the gray sand body development area according to the basement depth of the candidate area, the gray sand body development area satisfies the following conditions:

The buried depth of the basement in the middle of the gray sand body development area is smaller than that on both sides.
The method according to claim 1, wherein said performing borehole sampling analysis on a plurality of gray sand body development areas comprises:

Borehole analysis in each of the gray sand body development areas to determine sampling objects;

A plurality of samples of the sampling object are obtained for elemental analysis, and a uranium distribution area is delineated according to the results of the elemental analysis.
The method according to claim 6, wherein said drilling analysis in each said gray sand body development area to determine the sampling object:

Setting a plurality of drilling points in each gray sand body development area;

The drilling point is drilled to obtain the gray sand rate of each of the drilling points, and the gray sand rate is the ratio of the gray sand body thickness to the total sand body thickness in the red variegated layer at the drilling point ratio of

The gray sand body in the area where the drilling point with the lime-sand ratio is 0.2-0.7 is determined as the sampling object.
The method according to claim 6 or 7, wherein said obtaining a plurality of samples of said sampling object for elemental analysis comprises:

A plurality of sampling points are set in the sampling object to obtain a plurality of samples.
The method according to claim 8, wherein a sampling point is set at an interval of 0.5m.
The method according to claim 8 or 9, wherein said delineating the distribution area of uranium ore according to the result of said elemental analysis comprises:

When the elemental analysis result of the sample at one of the sampling points meets the expected value, the sampling point is determined as the uranium ore target area;

The uranium ore distribution area is delineated according to the distribution of the uranium ore target area, so that the uranium ore distribution area includes the uranium ore target area and the uranium ore distribution area is often in the shape of an island or a flower.
The method according to claim 10, wherein said elemental analysis comprises at least one of the following:

determining the content of uranium in said sample, determining the content of organic carbon in said sample, determining the content of acidolysis hydrocarbons in said sample, determining the correlation of uranium and FeO in said sample, determining the content of uranium and cobalt in said sample , nickel, molybdenum, and zinc.
The method according to claim 11, wherein, when the expected value of the elemental analysis result includes at least one of the following:

Uranium content > 12×10 -6 , organic carbon content > 0.25%, acid hydrolysis hydrocarbon content > 450μL·kg ‐1 , correlation between uranium and FeO > 0.5, positive correlation between uranium and cobalt, nickel, molybdenum and zinc.