Fine naming method of tight sandstone and rock mineral content determination method

Abstract

The present application relates to a kind of compact sandstone fine naming method and rock mineral content determination method, belong to rock mineral identification technical field.The fine naming method of the present application includes the following steps: obtaining the Fe element content, Al element content and Si element content in the skeleton of the rock to be named in target area, utilize skeleton X element content-dirt content model, skeleton aluminum element content-feldspar content model, skeleton silicon element content-quartz content model calculate dirt, feldspar and quartz content, then calculate dirt relative content, feldspar relative content and quartz relative content, and utilize sandstone triangular graph to fine name the rock in target area.The method can be in real time on the rock fine naming in oil drilling site, overcome the defect that rock mineral content is obtained after laboratory analysis is not continuous in fine naming rock, carry out compact oil and gas completion fine evaluation and test layer in drilling site, realize in improving interpretation precision, simultaneously, speed up oil and gas development process.

Description

Technical Field

[0001] This invention relates to a method for precise identification of dense sandstone and a method for determining the mineral content of rocks, belonging to the field of rock and mineral identification technology. Background Technology

[0002] With continuous advancements in oil and gas exploration and development technologies, the lower limit for efficient reserve development has been continuously decreasing, and global oil and gas development has entered the tight oil and gas sector. Since the 21st century, my country has made significant progress in tight oil and gas exploration, with tight oil and gas accounting for over 60% of newly added oil and gas reserves, representing approximately 35% of total reserves. Tight sandstone oil and gas reservoirs are often lithological gas reservoirs, where lithology plays a dominant role in the four properties relationship (property, water, and gas content), controlling physical properties, which in turn constrain oil (gas) content. For example, in the Ordos Upper Paleozoic tight sandstone gas reservoir, a typical representative area of ​​tight sandstone gas in my country, quartz content is positively correlated with porosity and gas saturation, while rock fragment content is negatively correlated with porosity. Under similar oil and gas show conditions, the gas production of quartz sandstone is clearly higher than that of rock fragment sandstone. Timely and precise rock identification is crucial for oil and gas reservoir evaluation.

[0003] Currently, rock identification at oil drilling sites relies primarily on visual observation. Sandstone identification is subdivided into five grades—gravel, coarse, medium, fine, and pulverized—based on grain size, failing to meet the requirement of precise identification based on rock mineral composition (quartz, rock fragments, feldspar). This hinders the role of rock classification in reservoir evaluation, limiting further improvements in reservoir evaluation accuracy and delaying the development of tight sandstone oil and gas. While laboratory analysis can determine rock mineral content and achieve precise rock identification, the long analysis cycle and discontinuous sampling make it difficult to meet production needs in terms of both analytical quantity and timeliness. Summary of the Invention

[0004] The purpose of this invention is to provide a method for finely naming dense sandstone, which enables real-time fine naming of rocks at the oil drilling site.

[0005] The present invention also provides a method for determining the rock mineral content of dense sandstone.

[0006] To achieve the above objectives, the technical solution adopted by the fine naming method for dense sandstone of the present invention is as follows:

[0007] A method for finely identifying dense sandstone includes the following steps:

[0008] 1) Obtain the content of element X in the framework of the unnamed rocks in the target area. 骨架 Al element content 骨架 and Si element content 骨架 The X element is either Fe or Ti.

[0009] 2) Utilizing the content of element X in the rock framework 骨架 Al element content 骨架 and Si element content 骨架 Substitute the values ​​into the mathematical models of X element content-rock fragment content, aluminum element content-feldspar content, and silicon element content-quartz content in the framework, respectively, and calculate the rock fragment content, feldspar content, and quartz content. Then calculate the relative rock fragment content, relative feldspar content, and relative quartz content in lithology identification.

[0010] 3) Based on the relative quartz content, relative feldspar content, and relative rock fragment content obtained in step 2), the rocks in the target area are precisely named using a sandstone triangulation plate.

[0011] The fine naming method for tight sandstone of the present invention can accurately name rocks in real time at the oil drilling site, with high timeliness and wider application. It can overcome the defect of discontinuous fine naming of rocks after obtaining rock mineral content from laboratory analysis. In addition, the fine naming method of the present invention can be used to carry out fine evaluation of tight oil and gas well completion and test layer selection at the drilling site, thereby improving the accuracy of interpretation and accelerating the oil and gas development process.

[0012] Furthermore, in step 2), the mathematical model for the X element content in the skeleton minus the rock fragment content is:

[0013] W 岩屑 =X 骨架 / X 岩屑 ;

[0014] In the formula: W 岩屑 : Percentage of rock fragments;

[0015] X 骨架 X element content in the sandstone framework;

[0016] X 岩屑 : Percentage content of element X in rock fragments.

[0017] Furthermore, in step 2), the mathematical model for the aluminum content versus feldspar content in the framework is as follows:

[0018] W 长石 =[Al 骨架 -Al 岩屑 *(Fe 骨架 / Fe 岩屑 )] / C5;

[0019] In the formula: W 长石 Feldspar content;

[0020] Al 骨架 Al content in the sandstone framework;

[0021] Al 岩屑 Al content in rock cuttings;

[0022] Fe 骨架 Fe content in the sandstone framework;

[0023] Fe 岩屑 Fe content in rock cuttings;

[0024] C5: Regional constant.

[0025] C5: Regional constant 0.099. The regional constant C5 is between 0.097 and 0.103, and is related to the feldspar type in the target area. It is determined by collecting a series of samples from the target area and sending them to the laboratory for analysis.

[0026] Furthermore, in step 2), the mathematical model for the silicon content versus quartz content in the framework is:

[0027] W 石英 ={Si 骨架 -Si 岩屑 *(Fe 骨架 / Fe 岩屑 )-C6*[Al 骨架 -Al 岩屑 *(Fe 骨架 / Fe 岩屑 )]} / Si 石英 ;

[0028] In the formula: W 石英 Quartz content;

[0029] Si 骨架 Si content in the sandstone framework;

[0030] Si 岩屑 Si content in rock cuttings;

[0031] Si 石英 The Si element content in quartz particles;

[0032] Fe 骨架 Fe content in the sandstone framework;

[0033] Fe 岩屑 Fe content in rock cuttings;

[0034] Al 骨架 Al content in the sandstone framework;

[0035] Al 岩屑 Al content in rock cuttings;

[0036] C6: Regional constant.

[0037] C6: Regional constant 3.1, which is related to the feldspar type in the target area. It is determined by collecting a series of samples from the target area and sending them to the laboratory for analysis.

[0038] The advantage of using the above method to calculate the Fe content in rock fragments, the Al content in feldspar, and the Si content in quartz is that Fe, Al, and Si are all essential elements in rocks, with high content and easy detection. The Si content in quartz is stable. In sandstone mineral composition from the same region and stratigraphic level (same provenance, similar sedimentary evolution), the Fe content in rock fragments is stable, and the Al content in feldspar is stable.

[0039] The technical solution adopted in the method for determining the rock mineral content of dense sandstone of the present invention is as follows:

[0040] A method for determining the mineral content of dense sandstone, comprising the following steps:

[0041] 1) Obtain the content of element X in the framework of the unnamed rocks in the target area. 骨架 Al element content 骨架 and Si element content 骨架 The X element is either Fe or Ti.

[0042] 2) Utilizing the content of element X in the rock framework 骨架 Al element content 骨架 and Si element content 骨架 Substitute these values ​​into the mathematical models for X element content-rock fragment content, aluminum element content-feldspar content, and silicon element content-quartz content in the framework, and calculate the rock fragment content, feldspar content, and quartz content respectively.

[0043] The method for determining the rock mineral content of dense sandstone of the present invention enables real-time analysis of rocks at the oil drilling site to obtain rock mineral content data, overcoming the shortcomings of poor timeliness and discontinuous depth of rock mineral content obtained by laboratory analysis.

[0044] Furthermore, in step 2), the mathematical model for the X element content in the skeleton minus the rock fragment content is:

[0045] W 岩屑 =X 骨架 / X 岩屑 ;

[0046] In the formula: W 岩屑 : Percentage of rock fragments;

[0047] X 骨架 X element content in the sandstone framework;

[0048] X 岩屑 : Percentage content of element X in rock fragments.

[0049] Furthermore, in step 2), the mathematical model for the aluminum content versus feldspar content in the framework is as follows:

[0050] W 长石 =[Al 骨架 -Al 岩屑 *(Fe 骨架 / Fe 岩屑 )] / C5;

[0051] In the formula: W 长石 Feldspar content;

[0052] Al 骨架 Al content in the sandstone framework;

[0053] Al 岩屑 Al content in rock cuttings;

[0054] Fe 骨架 Fe content in the sandstone framework;

[0055] Fe 岩屑 Fe content in rock cuttings;

[0056] C5: Regional constant.

[0057] C5: Regional constant 0.099. The regional constant C5 is between 0.097 and 0.103, and is related to the feldspar type in the target area. It is determined by collecting a series of samples from the target area and sending them to the laboratory for analysis.

[0058] Furthermore, in step 2), the mathematical model for the silicon content versus quartz content in the framework is:

[0059] W 石英 ={Si 骨架 -Si 岩屑 *(Fe 骨架 / Fe 岩屑 )-C6*[Al 骨架 -Al 岩屑 *(Fe 骨架 / Fe 岩屑 )]} / Si 石英 ;

[0060] In the formula: W 石英 Quartz content;

[0061] Si 骨架 Si content in the sandstone framework;

[0062] Si 岩屑 Si content in rock cuttings;

[0063] Si 石英 The Si element content in quartz particles;

[0064] Fe 骨架 Fe content in the sandstone framework;

[0065] Fe 岩屑 Fe content in rock cuttings;

[0066] Al 骨架 Al content in the sandstone framework;

[0067] Al 岩屑 Al content in rock cuttings;

[0068] C6: Regional constant.

[0069] C6: Regional constant 3.1, which is related to the feldspar type in the target area. It is determined by collecting a series of representative samples from the target area and sending them to the laboratory for analysis. Attached Figure Description

[0070] Figure 1 This is a fitting graph of the electrical clay content of rock samples from different strata in an oilfield in North China and the clay content in the laboratory.

[0071] Figure 2 The figure shows the fitting plot of the dolomite content calculated from the elements in rock samples from different strata of an oilfield in North China in the experimental example and the dolomite content in the laboratory.

[0072] Figure 3 The figure shows the fitting plot of the calcite content calculated from the elements in rock samples from different strata of an oilfield in North China, obtained in the experimental example, and the calcite content obtained in the laboratory.

[0073] Figure 4 This is a fitting graph of the rock fragment content calculated from the elements in rock samples from different strata of an oilfield in North China obtained in the experimental example and the rock fragment content obtained in the laboratory.

[0074] Figure 5 This is a fitting graph of the feldspar content calculated from the elements in rock samples from different strata of an oilfield in North China, obtained in the experimental example, and the feldspar content obtained in the laboratory.

[0075] Figure 6 The figure shows the fitting plot of the quartz content calculated from the elements in rock samples from different strata in an oilfield in North China, obtained in the experimental example, with the laboratory quartz content.

[0076] Figure 7This example illustrates a triangular diagram of fine-grained rock nomenclature based on electrical properties and elements from 51 rock samples from an oilfield in North China.

[0077] Figure 8 This is an experimental example of a triangular diagram illustrating the precise identification of 51 rock samples from an oilfield in North China. Detailed Implementation

[0078] The following uses an oilfield in North China as an example to further illustrate the technical solution of the present invention.

[0079] Example

[0080] The method for finely naming dense sandstone in this embodiment includes the following steps:

[0081] 1) First, core samples from different strata and lithologies in the study area were selected as the sampling objects. A 1-inch core column was taken and split in half in the middle, and the same number was assigned. Half of the sample was subjected to X-ray elemental analysis to obtain the mass percentage data of elements such as Al, Si, Fe and Ti in the biota. At the same time, the drilling GR data values ​​of the core corresponding to the well depth were extracted, as shown in Table 1.

[0082] Table 1. Rock element and electrical data

[0083]

[0084]

[0085] 2) Pure mudstone interlayers in sandstone reservoirs of each target layer in the study area were selected as the target rocks. Elemental logging was performed on the mudstone interlayers to obtain the chemical element content of the sampled rocks. A standard mudstone (100% mudstone content) elemental content model was established. Based on the mudstone content at different depths and the corresponding standard mudstone elemental content model, the elemental content of mudstone at different depths was forward calculated. The contents of Si, Fe, Al, and Ti were denoted as Si, Fe, Al, and Ti, respectively. 标准 Fe 标准 Al 标准 Ti 标准 .

[0086] 3) Core samples of lithic sandstone from each target layer were selected in the study area. After physical crushing, the lithic fragments were selected as the target for elemental logging analysis to obtain the elemental content of the lithic fragments (the elemental content of lithic fragments varies in different areas due to the influence of the parent rock). The elemental content of Si, Fe, Al, and Ti was denoted as Si. 岩屑 Fe 岩屑 Al 岩屑 Ti 岩屑 .

[0087] 4) Calculate clay content using natural gamma curve:

[0088] SH = (GR - GR) min ) / (GR max -GR min )

[0089] W SH =(2 SH*C1 -1) / (2 C1 -1)

[0090] In the formula: W SH : Percentage of mud content

[0091] SH: Gamma Relative Value;

[0092] GR: Natural Gamma Logging Value, API;

[0093] GR min API (Advanced Gamma-Ray Value) for pure sandstone.

[0094] GR max Natural gamma value (API) in pure mudstone;

[0095] C1: Empirical coefficient, 2 for old strata and 3.7 for new strata. This example uses a new stratum. The calculated clay content of each sample is shown in Table 2.

[0096] Table 2 shows the calculated clay content, elemental content in the rock skeleton of each sample, and rock mineral content.

[0097]

[0098]

[0099] 5) Calculate the content of dolomite and calcite using a carbonate rock calculation model.

[0100] The carbonate rock model includes mathematical models for dolomite and calcite content. Mathematical models for the percentage content of dolomite and calcite are established using the detected Mg and Ca elemental contents.

[0101] W 白云石 =Mg*C2

[0102] W 白云石 Dolomite content;

[0103] Mg: Percentage content of Mg element;

[0104] C2: constant 7.67;

[0105] W 方解石 =(Ca-Mg*C3)*C4

[0106] W 方解石 : Percentage of calcite;

[0107] Ca: Percentage content of Ca element;

[0108] Mg: Percentage content of Mg element;

[0109] C3: constant 1.67, the ratio of Ca to Mg in dolomite;

[0110] C4: constant 2.5.

[0111] The contents of dolomite and calcite calculated based on the carbonate rock model are shown in Table 2.

[0112] 6) Calculate the content of Si, Fe, Al and Ti elements in the rock skeleton using the difference method.

[0113] The mineral composition of the rock framework mainly includes quartz, feldspar, and rock fragments. The composition of quartz, feldspar, and rock fragments is closely related to the elements Si, Fe, Al, and Ti. First, the Si, Fe, Al, and Ti element contents in the argillaceous material are subtracted from the detected Si, Fe, Al, and Ti element contents to obtain the Si, Fe, Al, and Ti element contents in the sandstone framework. 骨架 Fe 骨架 Al 骨架 Ti 骨架 ;

[0114] Si 骨架 =Si 检测 -Si 标准 *W SH

[0115] Where: Si 骨架 Si content in the sandstone framework;

[0116] Si 检测 : Si element detection value from X-ray elemental logging instrument;

[0117] Si 标准 Si content in standard mudstone in the target area;

[0118] W SH : Percentage of mudstone in sandstone.

[0119] Fe 骨架 =Fe 检测 -Fe 标准 *W SH

[0120] Where: Fe 骨架 Fe content in the sandstone framework;

[0121] Fe 检测 Fe element detection value from X-ray elemental logging instrument;

[0122] Fe 标准 Fe content in standard mudstone of the target area;

[0123] W SH : Percentage of mudstone in sandstone.

[0124] Al 骨架 =Al 检测 -Al 标准 *W SH

[0125] In the formula: Al 骨架 Al content in the sandstone framework;

[0126] Al 检测 Al element detection values ​​from X-ray elemental logging instrument;

[0127] Al 标准 Al content in standard mudstone of the target area;

[0128] W SH : Percentage of mudstone in sandstone.

[0129] Ti 骨架 =Ti 检测 -Ti 标准 *W SH

[0130] In the formula: Al 骨架 Al content in the sandstone framework;

[0131] Ti 检测 Ti element detection value from X-ray elemental logging tool;

[0132] Al 标准 Al content in standard mudstone of the target area;

[0133] W SH : Percentage of mudstone in sandstone.

[0134] The contents of Si, Fe, and Al elements in the rock skeleton calculated using the difference method are shown in Table 2.

[0135] 7) Calculate the rock fragment content using the rock fragment content calculation model.

[0136] Rock fragment content is calculated using either Fe or Ti. Based on regional geological characteristics, a preferred major element from Fe and Ti is selected as the model for calculating rock fragment content, with Fe generally chosen. The model for calculating rock fragment content using Fe is as follows:

[0137] W 岩屑 =Fe 骨架 / Fe岩屑

[0138] In the formula: W 岩屑 : Percentage of rock fragments;

[0139] Fe 骨架 Fe content in the sandstone framework;

[0140] Fe 岩屑 : Percentage of Fe element in rock cuttings;

[0141] The rock fragment content calculated from Fe is shown in Table 2. Furthermore, the rock fragment content can also be calculated using Ti, as shown in the following model:

[0142] W 岩屑 =Ti 骨架 / Ti 岩屑

[0143] In the formula: W 岩屑 : Percentage of rock fragments;

[0144] Ti 骨架 : Percentage of Ti element in the skeleton;

[0145] Ti 岩屑 : Percentage of Ti element in rock fragments.

[0146] 8) Calculate the feldspar content using the feldspar content calculation model.

[0147] Al is only found in feldspar and rock fragments in the rock skeleton. The difference between the Al content in the rock skeleton and the Al content in the rock fragments is the Al content in feldspar. The Al content in feldspar can be used to calculate the feldspar content.

[0148] The calculation model for feldspar content is as follows:

[0149] W 长石 =[Al 骨架 -Al 岩屑 *(Fe 骨架 / Fe 岩屑 )] / C5

[0150] In the formula: W 长石 Feldspar content;

[0151] Al 骨架 Al content in the sandstone framework;

[0152] Al 岩屑 Al content in rock cuttings;

[0153] Fe 骨架 Fe content in the sandstone framework;

[0154] Fe 岩屑 Fe content in rock cuttings;

[0155] C5: Regional constant 0.099. The regional constant C5 ranges from 0.097 to 0.103 and is related to the feldspar type in the target area. It is determined by collecting a series of samples from the target area and sending them to the laboratory for analysis. The feldspar content calculated from Al is shown in Table 2.

[0156] 9) Calculate the quartz content using a quartz content calculation model.

[0157] The silicon (Si) element in the rock framework is composed of Si elements in quartz, rock fragments, and feldspar. The Si content in the rock framework minus the Si content in the rock fragments and feldspar gives the Si content in quartz. The quartz content can then be calculated using the Si content in quartz. The quartz content calculation model is as follows:

[0158] W 石英 ={Si 骨架 -Si 岩屑 *(Fe 骨架 / Fe 岩屑 )-C6*[Al 骨架 -Al 岩屑 *(Fe 骨架 / Fe 岩屑 )]} / Si 石英

[0159] In the formula: W 石英 Quartz content;

[0160] Si 骨架 Si content in the sandstone framework;

[0161] Si 岩屑 Si content in rock cuttings;

[0162] Si 石英 The Si element content in quartz particles;

[0163] Fe 骨架 Fe content in the sandstone framework;

[0164] Fe 岩屑 Fe content in rock cuttings;

[0165] Al 骨架 Al content in the sandstone framework;

[0166] Al 岩屑 Al content in rock cuttings;

[0167] C6: Regional constant 3.1, which is related to the feldspar type in the target area. It is determined by collecting a series of samples from the target area and sending them to the laboratory for analysis.

[0168] The quartz content calculated using the above quartz content model is shown in Table 2.

[0169] In addition, the total mineral content of rocks can be calculated using the summation method, which states that the rocks are composed of argillaceous material, carbonate rocks (calcite and dolomite), and a grainy framework (quartz, feldspar, and rock fragments). The quartz content is calculated as 1 minus the content of other minerals. The calculation model is as follows:

[0170] W 石英 =1-W SH -S 白云石 -S 方解石 -W 岩屑 -W 长石

[0171] In the formula: W 石英 Quartz content;

[0172] W SH : Percentage of clay content;

[0173] W 白云石 Dolomite content;

[0174] W 方解石 : Percentage of calcite;

[0175] W 岩屑 : Percentage of rock fragments;

[0176] W 长石 Feldspar content: percentage.

[0177] 10) Fine-grained rock identification

[0178] Based on the sandstone classification triangular diagram, the rock minerals in the diagram are relative contents. The calculation models for the relative contents of rock fragments, feldspar, and quartz in the lithological fine identification model are as follows:

[0179] Relative rock fragment content = W 岩屑 / (W 岩屑 +W 长石 +W 石英 );

[0180] Feldspar relative content = W 长石 / (W 岩屑 +W 长石 +W 石英 );

[0181] Quartz relative content = W 石英 / (W 岩屑 +W 长石 +W石英 ).

[0182] Based on the calculated relative contents of rock fragments, feldspar, and quartz, a sandstone classification triangular chart is used for fine-grained rock identification, such as... Figure 7 As shown.

[0183] The calculated relative contents of rock fragments, feldspar, and quartz, as well as the results of detailed rock identification, are shown in Table 3.

[0184] Table 3 shows the calculated relative mineral contents and rock identification results.

[0185]

[0186]

[0187] An embodiment of the method for determining the rock mineral content of dense sandstone, the specific steps are the same as steps 1-9 of the embodiment of the method for fine naming of dense sandstone described above, and will not be repeated here.

[0188] Experimental Example

[0189] The other half of each sample from step 1) of the embodiment was sent to the laboratory for mineral composition analysis to obtain the percentage content data of rock mineral components. Based on the determined rock mineral content, the rock was named using a sandstone naming triangle chart, such as... Figure 8 As shown, the results are presented in Table 4.

[0190] Table 4. Percentage data and identification results of rock mineral composition.

[0191]

[0192]

[0193]

[0194] The clay content, dolomite content, calcite content, rock fragment content, feldspar content, and stone content calculated in Table 2 of the examples were fitted with the corresponding laboratory analysis data in Table 3. See the attached graphs. Figures 1-6 The absolute correlation coefficients for fitting the same mineral content were all above 0.9, reaching 0.9052, 0.9102, 0.9305, 0.9317, 0.9789 and 0.9889 respectively, indicating that the mineral content calculated by the present invention is accurate and reliable.

[0195] Comparing the rock names identified in the embodiments of the present invention (see Table 3) with the rock names identified in the laboratory (see Table 4), it can be seen that the lithological identification (sandstone, mudstone) is completely consistent. The comparison of the triangular plot of the detailed rock naming in the embodiments and the laboratory (see Table 4) further confirms this. Figure 7 and Figure 8 The analysis revealed one instance of incorrect naming of the primary mineral in sandstone: sample 47, a lithic sandstone, was incorrectly named feldspathic sandstone, resulting in a 98.0% accuracy rate. Four additional instances of combined primary and secondary mineral naming errors were observed: samples 23, 31, 32, and 50. Samples 31, 32, and 50, which are lithic quartz sandstone, were incorrectly named feldspathic quartz sandstone; sample 23, a lithic sandstone, was incorrectly named feldspathic lithic sandstone. The overall accuracy rate for combined primary and secondary mineral naming was 90.2%. The rock fine identification method established using drilling GR and elemental data achieved a 98.0% accuracy rate, demonstrating the accuracy and reliability of the rock fine identification method of this invention. Even with secondary mineral naming included, the fine identification accuracy rate remained above 90%, meeting the needs of field production.

[0196] The rock fine identification method of the present invention can calculate rock mineral content and rock fine identification in real time at the oil drilling site, with high timeliness and can obtain rock mineral content and rock fine identification for continuous well depths, making it more widely applicable and overcoming the problem of discontinuous rock mineral content and rock fine identification obtained from laboratory analysis. In addition, the technical solution of the present invention can be used to carry out fine evaluation of tight oil and gas well completion and test layer selection at the drilling site, improving interpretation accuracy and accelerating the oil and gas development process.

Claims

1. A method for finely identifying dense sandstone, characterized in that: Includes the following steps: 1) Obtain the content of element X in the framework of the unnamed rocks in the target area. 骨架 Al element content 骨架 and Si element content Si 骨架 The X element is either Fe or Ti. 2) The content of element X in the rock framework X 骨架 Al element content 骨架 and Si element content Si 骨架 Substitute the values ​​into the mathematical models of X element content-rock fragment content, aluminum element content-feldspar content, and silicon element content-quartz content in the framework, respectively, and calculate the rock fragment content, feldspar content, and quartz content. Then calculate the relative rock fragment content, relative feldspar content, and relative quartz content in lithology identification. The mathematical model for the X element content versus rock fragment content in the skeleton is as follows: W 岩屑 = X 骨架 / X 岩屑 In the formula: W 岩屑 : Percentage of rock fragments; X 骨架 X element content in the sandstone framework; X 岩屑 : Percentage content of element X in rock cuttings; The mathematical model for the aluminum content versus feldspar content in the skeleton is as follows: W 长石 = [Al 骨架 -Al 岩屑 *(Fe 骨架 / Fe 岩屑 (] / C5 In the formula: W 长石 Feldspar content; Al 骨架 Al content in the sandstone framework; Al 岩屑 Al content in rock cuttings; Fe 骨架 Fe content in the sandstone framework; Fe 岩屑 Fe content in rock cuttings; C5: Regional constant; The mathematical model for the silicon content versus quartz content in the skeleton is as follows: W 石英 ={Si 骨架 -Yes 岩屑 *(Fe 骨架 / Fe 岩屑 )-C6*[Al 骨架 -Al 岩屑 *(Fe 骨架 / Fe 岩屑 )]} / Si 石英 In the formula: W 石英 Quartz content; Si 骨架 Si content in the sandstone framework; Si 岩屑 Si content in rock cuttings; Si 石英 The Si element content in quartz particles; Fe 骨架 Fe content in the sandstone framework; Fe 岩屑 Fe content in rock cuttings; Al 骨架 Al content in the sandstone framework; Al 岩屑 Al content in rock cuttings; C6: Region constant; 3) Based on the relative quartz content, relative feldspar content, and relative rock fragment content obtained in step 2), the rocks in the target area are precisely named using a sandstone triangulation plate.

2. The method for finely identifying dense sandstone according to claim 1, characterized in that: In step 2), the regional constant C5 is between 0.097 and 0.

103.

3. The method for finely identifying dense sandstone according to claim 2, characterized in that: In step 2), the region constant C5 is 0.

099.

4. The method for finely identifying dense sandstone according to claim 1, characterized in that: In step 2), the region constant C6 is 3.

1.

5. A method for determining the rock mineral content of dense sandstone, characterized in that: Includes the following steps: 1) Obtain the content of element X in the framework of the unnamed rocks in the target area. 骨架 Al element content 骨架 and Si element content Si 骨架 The X element is either Fe or Ti. 2) Utilizing the content of element X in the rock framework 骨架 Al element content 骨架 and Si element content Si 骨架 Substitute these values ​​into the mathematical models for X element content-rock fragment content, aluminum element content-feldspar content, and silicon element content-quartz content in the framework, and calculate the rock fragment content, feldspar content, and quartz content respectively. The mathematical model for the X element content versus rock fragment content in the skeleton is as follows: W 岩屑 = X 骨架 / X 岩屑 In the formula: W 岩屑 : Percentage of rock fragments; X 骨架 Fe content in the sandstone framework; X 岩屑 : Percentage content of element X in rock cuttings; The mathematical model for the aluminum content versus feldspar content in the skeleton is as follows: W 长石 = [Al 骨架 -Al 岩屑 *(Fe 骨架 / Fe 岩屑 (] / C5 In the formula: W 长石 Feldspar content; Al 骨架 Al content in the sandstone framework; Al 岩屑 Al content in rock cuttings; Fe 骨架 Fe content in the sandstone framework; Fe 岩屑 Fe content in rock cuttings; C5: Regional constant; The mathematical model for the silicon content versus quartz content in the skeleton is as follows: W 石英 ={Si 骨架 -Yes 岩屑 *(Fe 骨架 / Fe 岩屑 )-C6*[Al 骨架 -Al 岩屑 *(Fe 骨架 / Fe 岩屑 )]} / Si 石英 In the formula: W 石英 Quartz content; Si 骨架 Si content in the sandstone framework; Si 岩屑 Si content in rock cuttings; Si 石英 The Si element content in quartz particles; Fe 骨架 Fe content in the sandstone framework; Fe 岩屑 Fe content in rock cuttings; Al 骨架 Al content in the sandstone framework; Al 岩屑 Al content in rock cuttings; C6: Regional constant.

6. The method for determining the rock mineral content of dense sandstone according to claim 5, characterized in that: In step 2), the regional constant C5 is between 0.097 and 0.

103.

7. The method for determining the rock mineral content of dense sandstone according to claim 6, characterized in that: In step 2), the region constant C5 is 0.

099.

8. The method for determining the rock mineral content of dense sandstone according to claim 5, characterized in that: In step 2), the region constant C6 is 3.1.

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