CN-121994846-A - Method for quantifying content of dolomites isomorphism

CN121994846ACN 121994846 ACN121994846 ACN 121994846ACN-121994846-A

Abstract

The invention discloses a method for quantifying content of dolomitic homoids, and relates to the technical field of oil and gas reservoir exploration and research. According to the method, rock mineral identification, scanning electron microscope experiments, energy spectrum analysis experiments, X-ray fluorescence spectrum experiments and X-ray diffraction experiments are respectively carried out on rock slices and rock powder, whether dolomite, iron dolomite and manganese dolomite exist or not is judged, percentages of the dolomite, the iron dolomite and the manganese dolomite are determined, diffraction peaks of the iron dolomite and the manganese dolomite are subjected to peak separation treatment, finally, full spectrum fitting is carried out on the diffraction peaks of the three obtained by fitting, sequence peaks of the three in a diffraction spectrogram are fitted, and mass fractions of various minerals in a sample are calculated by utilizing a theoretical diffraction spectrogram which is finally fitted, so that the content of dolomite homomorphic substances is quantified. The invention overcomes the defects of the traditional rock slice identification and element analysis methods in quantitative accuracy, realizes the accurate quantification of the content of the dolomitic homoids, and improves the accuracy and reliability of analysis.

Inventors

TAN JIE
LUO BING
WANG LI
CHEN MANFEI
CHEN HONGBIN
WANG KE

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260508
Application Date: 20241106

Claims (14)

1. A method for quantifying the content of dolomite homomorphic bodies comprises the steps of S1, selecting dolomite samples, obtaining rock flakes and rock powder, S2, carrying out rock mineral identification on the rock flakes, judging whether dolomite and iron dolomite exist simultaneously, S3, carrying out scanning electron microscope experiments and energy spectrum analysis experiments on the rock flakes, obtaining the content of the dolomite, the iron dolomite and the manganese dolomite according to the morphological characteristics of minerals and the distribution characteristics of energy spectrum elements, S4, dividing the rock powder of S1 into two parts, carrying out X-ray fluorescence spectrum experiments on one part, judging whether the iron dolomite and the manganese dolomite exist or not, and obtaining the content of the dolomite, the iron dolomite and the manganese dolomite, and the method is characterized by further comprising the following steps: S5, carrying out an X-ray diffraction experiment on the other rock powder in the S4; s6, carrying out transverse peak splitting treatment on diffraction peaks of the iron dolomite and the manganese dolomite according to the diffraction spectrogram tested by the X-ray diffraction experiment in the S5; S7, taking weighted averages of the percentages of the dolomite, the iron dolomite and the manganese dolomite obtained in the S3 and the S4 as real area percentages of the dolomite, the iron dolomite and the manganese dolomite, taking the weighted averages as diffraction peak intensity relations of the three, determining peak dividing positions of the dolomite, the iron dolomite and the manganese dolomite according to the diffraction peak intensity relations of the three, and carrying out longitudinal peak dividing treatment; S8, carrying out full spectrum fitting on the fitted diffraction peaks of dolomite, iron dolomite and manganese dolomite, fitting the sequence peak average of the diffraction peaks in the diffraction spectrum, and calculating the mass fraction of each mineral in the sample by using the finally fitted theoretical diffraction spectrum to serve as a quantitative result of the content of the dolomite homomorphic body.
2. The method for quantifying the content of the dolomitic homoids according to claim 1, wherein in the step S6, the transverse peak splitting treatment is to split the diffraction peaks of the dolomites and the manganese dolomites in the X-axis direction of the diffraction patterns according to the double diffraction angles of the characteristic diffraction peaks of the dolomites and the manganese dolomites.
3. The method for quantifying the content of the dolomitic homoids according to claim 1, wherein in the step S7, the peak splitting positions of the dolomite, the iron dolomite and the manganese dolomite are determined according to the diffraction peak intensity relation of the three, and the longitudinal peak splitting treatment is that the peak splitting positions are determined in the diffraction spectrogram according to the double diffraction angles and the diffraction intensities of the diffraction main peaks of the three due to the overlapping phenomenon of the main peak positions of the dolomite, the iron dolomite and the manganese dolomite in the X-ray diffraction spectrogram; and then dividing the diffraction peaks according to the diffraction intensities of the diffraction peaks of the dolomite, the iron dolomite and the manganese dolomite, and separating the diffraction peaks of the dolomite, the iron dolomite and the manganese dolomite in the Y-axis direction of the diffraction spectrogram.
4. The method for quantifying the content of the dolomitic isoids according to claim 1, wherein in the step S1, the rock flakes are obtained through rock tabletting, the rock tabletting meets the technical requirements of the rock tabletting method SY/T5913-2004, and mixed liquor is adopted for dyeing in the tabletting process, and the mixed liquor is mixed according to alizarin red S solution and potassium ferricyanide solution in a volume ratio of 3:2.
5. The method for quantifying the content of the dolomitic homoid according to claim 1, wherein in the step S1, rock powder is obtained through rock grinding, the rock grinding is required to meet the technical requirements of SY/T5163-2018, the technical requirements of a method for analyzing clay minerals and common non-clay minerals in sedimentary rocks by X-ray diffraction, the crushed rock sample is ground to be less than 200 meshes in total particle size, the size is uniform, and the finger kneading is free of granular sensation.
6. The method for quantifying the content of the dolomitic homoids according to claim 1, wherein in the step S2, the rock mineral identification is performed according to the optical property of the dolomite under a polarizing microscope, namely, the area where the dolomite is broken is judged according to the mineral staining condition, and the area is the dolomite or the iron dolomite.
7. The method for quantifying the content of the dolomitic homoids according to claim 6, wherein the mineral staining conditions comprise non-staining, light blue and dark blue, wherein the non-staining is dolomite, the light blue is iron-containing dolomite, and the dark blue is iron-containing dolomite, wherein the iron content in the iron-containing dolomite is less than 25%, and the iron content in the iron-containing dolomite is greater than 25%.
8. The method for quantifying the content of the dolomitic isoids according to claim 1, wherein in the step S3, the scanning electron microscope experiment meets the technical requirements of a rock sample scanning electron microscope analysis method SY/T5162-2021.
9. The method for quantifying the content of the dolomitic isoids according to claim 1, wherein in the step S3, the energy spectrum analysis experiment meets the technical requirements of a rock mineral energy spectrum quantitative analysis method SY/T6189-2018.
10. The method for quantifying the content of the dolomitic isoids according to claim 1, wherein in the step S4, the X-ray fluorescence spectrum experiment meets the technical requirement of the general rule of fluorescence spectrum analysis method, JY/T0571-2020.
11. The method for quantifying the content of the dolomitic homoids according to claim 1, wherein in the step S4, the content of the iron element in the experimental result of the X-ray fluorescence spectrum is less than 25%, the iron element is more than 25%, the iron dolomite is judged, the manganese element is less than 25%, the manganese dolomite is judged, and the manganese element is more than 25%, the manganese dolomite is judged.
12. The method for quantifying the content of the dolomites isomorphic body according to claim 1, wherein in the step S4, the step of obtaining the percentage content of the dolomite, the iron dolomite and the manganese dolomite in the sample comprises the step of calculating the percentage content of the dolomite, the iron dolomite and the manganese dolomite in the sample according to the percentage content relation of the calcium, the magnesium, the iron and the manganese elements in the experimental result of the X-ray fluorescence spectrum and combining the percentage content relation of the calcium, the magnesium, the iron and the manganese elements in the standard minerals of the dolomite, the iron dolomite and the manganese dolomite.
13. The method for quantifying the content of the dolomitic isoids according to claim 1, wherein in the step S5, an X-ray diffraction experiment is required to meet the technical requirements of SY/T5163-2018, which is a method for analyzing X-ray diffraction of clay minerals and common non-clay minerals in sedimentary rocks.
14. The method for quantifying the content of the dolomitic homoids according to claim 1, wherein in the step S8, the full spectrum fitting meets the technical requirements of the Ritevolde graph fitting correction method.

Description

Method for quantifying content of dolomites isomorphism Technical Field The invention relates to the technical field of oil and gas reservoir exploration and research, in particular to a method for quantifying content of dolomites isomorphism. Background Dolomite is used as a common carbonate rock oil-gas reservoir layer taking dolomite as a main mineral type, and has the advantages of multiple types, large formation time span and complex cause. In deep and ancient sea-phase layers, dolomite is easier to form into good quality reservoirs than limestone. Taking Sichuan basin as an example, the cogongrass group and the lamp shadow group in the area are main oil and gas resource reservoirs, and the reservoir performance of dolomite in the reservoirs is very good, so that the cogongrass group and the lamp shadow group are important occurrence places of oil and gas resources. Dolomite is a main mineral which forms dolomite, dolomite which is a cause of sea phase deposition often forms a layer with siderite layer and limestone layer to be produced, and dolomite which is a cause of lake phase deposition often forms symbiosis with gypsum, anhydrite, rock salt and the like. The dolomites are mainly composed of iron dolomites and manganese dolomites, and according to the content characteristics of the dolomites, the dolomites are analyzed according to the content of the dolomites, so that the formation mechanism and evolution characteristics of the dolomite reservoir can be known more deeply, and scientific basis is provided for the analysis of the dolomite causes. At present, the method for analyzing the dolomitic homomorphism at home and abroad mainly depends on a rock slice identification method, a scanning electron microscope analysis method, an element analysis method and the like. The rock slice identification method can distinguish dolomite and iron dolomite according to the color change of minerals, but is limited by optical resolution, the content of the dolomite cannot be accurately quantified, the scanning electron microscope analysis method can analyze the microstructure of minerals, and can identify the homomorphism by combining energy spectrum analysis with element components, but the quantitative analysis of the content of the homomorphism cannot be realized because the element is difficult to accurately reconstruct the true content of the minerals, and the element analysis method is also called a chemical analysis method, and judges whether the homomorphism exists or not by analyzing the composition and content difference of the element. The Chinese patent literature with publication number of CN116935982A and publication number of 2023, 10 and 24 discloses a semi-quantitative analysis method for mineral content in a debris flow sample, which is characterized in that the debris flow sample is screened to be not more than 0.075 mm, XRD testing and XRF element analysis are carried out on the screened debris flow sample, diffraction peaks obtained by XRD testing are matched according to an X-ray diffraction standard card, minerals corresponding to the XRF elements are selected, the types of the minerals in the debris flow are determined according to the matching degree of the elements and diffraction angles, the relative content of each mineral is calculated based on the chemical formula and the XRF data of the mineral types determined in the step S2, the relative content of each mineral is normalized, and finally the relative proportion of each mineral is obtained. The measuring method comprises an X-ray fluorescence spectrum experiment and an X-ray diffraction experiment, and the relative content of each mineral is calculated. However, the technical scheme cannot distinguish the same elements in different mineral phases, so that accurate quantification of the content of the dolomitic homoids cannot be realized, and on the other hand, the technology performs matching analysis on only a single peak, so that the error is relatively large. Disclosure of Invention In order to overcome the defects and shortcomings in the prior art, the invention provides a method for quantifying the content of dolomitic isoids. The invention aims to solve the problem that the existing method can only identify dolomitic homoids and cannot quantify the dolomitic homoids. The invention identifies the dolomitic analogue, uses scanning electron microscope and energy spectrum, X-ray fluorescence spectrum to obtain the shape and element information of the dolomitic, uses X-ray diffraction peak separation technique and full spectrum fitting technique to obtain the structure information of the dolomitic analogue, combines mathematical physical calculation method to quantify the content of the dolomitic analogue, and finds a solving way for fundamentally quantifying the content of the dolomitic analogue. In order to solve the problems in the prior art, the invention is realized by the following technical scheme: the invention provides