CN-122016590-A - Shale heterogeneity microscale fine characterization method and system

CN122016590ACN 122016590 ACN122016590 ACN 122016590ACN-122016590-A

Abstract

The invention discloses a shale heterogeneity microscale fine characterization method and system. The method comprises the steps of preparing a sheet sample of a target tattoo based on a shale reservoir rock core sample of a high-density thin-ultrathin tattoo to be detected, wherein the target tattoo is a single tattoo or a layer couple mainly comprising the single tattoo, and transversely dividing the sheet sample along the direction of the target tattoo to obtain a first sub-sheet sample, a second sub-sheet sample and a third sub-sheet sample, and respectively obtaining macroscopic information, microscopic information, organic matter abundance and oiliness data of the total porosity, organic-inorganic components and pore structure integration of the target tattoo. The invention can realize in-situ quantitative and multi-scale imaging analysis of the composition, organization and physical property integration in the same view field of the same sample, find out the organic and inorganic composition of a single grain layer, the structural characteristics of a hole seam and the difference between different grain layers, and realize the effective analysis of shale heterogeneity of a development high-density millimeter-micrometer-level grain layer section.

Inventors

WEI ZHIHONG
WEI XIANGFENG
HUANG QINGQIU
WANG QINGBO
HAO JINGYU
LIU ZHUJIANG
WANG QIANG
XIAO JILIN

Assignees

中国石油化工股份有限公司
中国石油化工股份有限公司勘探分公司

Dates

Publication Date: 20260512
Application Date: 20241112

Claims (10)

1. A shale heterogeneity microscale fine characterization method, comprising: Preparing a thin plate sample of a target stratum based on a shale reservoir core sample of a high-density thin-ultrathin stratum to be detected; wherein the target tattoo is a single tattoo or a layer pair with the single tattoo as a main part; transversely dividing the sheet sample along the layer-following direction of the target grain layer to obtain a first sub-sheet sample, a second sub-sheet sample and a third sub-sheet sample; Based on the first sub-sheet sample, simultaneously measuring the effective pore volume of high-pressure helium and the pore volume of nuclear magnetic fluid in an original state, and further obtaining the total porosity of the target stratum; Carrying out in-situ micro-area quantitative-imaging analysis based on the second sub-sheet sample by combining multi-scale optics with an electron microscope to obtain macroscopic information and microscopic information of the organic-inorganic components and pore structure integration of the target tattoo; And carrying out geochemical quantitative analysis based on the third sub-sheet sample to obtain the organic matter abundance and oil content data of the target tattoo.
2. The shale non-uniformity micro-scale fine characterization method according to claim 1, wherein the co-measuring the effective pore volume of high pressure helium and the pore volume of nuclear magnetic fluid based on the first sub-sheet sample in the original state, and further obtaining the total porosity of the target tattoo comprises: Pretreating the first sub-sheet sample, including drying and constant temperature treatment; determining the total volume of the pretreated first sub-sheet sample; carrying out high-pressure helium injection method porosity analysis by adopting a porosity measurement method under a pressure-covering condition on the basis of the pretreated first sub-sheet sample to obtain the effective pore volume of high-pressure helium; determining the nuclear magnetic fluid pore volume by adopting a two-dimensional nuclear magnetic method based on the pretreated first sub-sheet sample; and calculating the total porosity of the target grain layer based on the nuclear magnetic fluid pore volume and the high-pressure helium effective pore volume and the total volume.
3. The shale non-uniformity micro-scale fine characterization method according to claim 1, wherein the performing in-situ micro-area quantitative-imaging analysis based on the second sub-sheet sample by using a multi-scale optical and electron microscope, obtaining macroscopic information and microscopic information of the organic-inorganic component and pore structure integration of the target tattoo comprises: preparing the second sub-sheet sample into a common sample suitable for partial inverse fluorescence microscopy and scanning electron microscopy analysis; Carrying out fine analysis on the constitution of the target tattoo based on the common sample and the partial inverse fluorescence microscope, and initially selecting a target tattoo determination area; Carrying out carbon plating treatment on the common sample to obtain a carbon plated sample; carrying out quantitative evaluation of full-view scanning electron microscope minerals and quantitative analysis of components of a primary selected target tattoo determination area based on the carbon-plated sample, and quantitatively characterizing element content and mineral composition characteristics of the carbon-plated sample; performing field emission scanning electron microscope large-view high-resolution imaging scanning based on the carbon-plated sample, and accurately delineating a target tattoo determination area by combining a component quantitative analysis result of the initially selected target tattoo area; Polishing, carbon clearing and oil immersion are sequentially carried out on the carbon-plated sample to obtain an oil-immersed sample; Carrying out organic petrography analysis of a partial anti-fluorescence microscope based on the oil immersed sample, finely characterizing organic microscopic components of the oil immersed sample, and simultaneously, carrying out delineation and marking on specific organic and inorganic target areas by adopting an etching method; Polishing and carbon plating are sequentially carried out on the oil immersed sample to obtain a secondary carbon plating sample; developing component-composition integrated high-resolution imaging characterization of a field emission scanning electron microscope and a focused ion beam scanning electron microscope based on the secondary carbon plating sample and the specific organic and inorganic target areas to obtain microscopic information of components and aperture structures of the specific organic and inorganic target areas, and splicing the scanning images of the specific organic and inorganic target areas to obtain imaging results of typical macroscopic views; And (3) carrying out high-resolution imaging and comprehensive analysis of two-dimensional nuclear hysteresis oil occurrence characteristics on the common sample based on a low-voltage secondary electron mode of a field emission scanning electron microscope, and quantitatively-imaging to finely characterize the occurrence state of the retention oil.
4. The shale non-uniformity micro-scale fine characterization method according to claim 1, wherein the performing geochemical quantitative analysis based on the third sub-sheet sample, obtaining organic matter abundance and oiliness data of the target tattoo comprises: and grinding the third sub-sheet sample to a particle size of less than 200 mu m, analyzing the total organic carbon content and rock pyrolysis parameters of the third sub-sheet sample, and quantitatively characterizing the organic component characteristics of the target grain layer.
5. The shale non-uniformity micro-scale fine characterization method according to claim 1, wherein the sheet sample is 50-70 mm in length, 20-25 mm in width and 4mm in thickness.
6. The shale non-uniformity micro-scale fine characterization method of claim 5, wherein the length of the first sub-sheet sample is 40-60 mm.
7. The shale non-uniformity micro-scale fine characterization method of claim 6, wherein the second sub-sheet sample and the third sub-sheet sample are each 5mm in length.
8. The shale non-uniformity micro-scale fine characterization method according to claim 3, wherein the length of the common sample is 5-7 mm, the width is 4mm, and the thickness is 5mm.
9. The shale non-uniformity micro-scale fine characterization method according to claim 2, wherein the calculation expression of the total porosity is: φ t ＝(V oe +V of )/V t ×100%; Wherein V oe is the high pressure helium effective void volume, V of is the nuclear magnetic fluid void volume, V t is the total volume of the first sub-sheet sample, and Φ t is the total porosity.
10. A shale non-homogeneity microscale fine characterization system, comprising: The preparation module is used for preparing a thin plate sample of the target stratum based on a shale reservoir core sample of the high-density thin-ultrathin stratum to be detected; wherein the target tattoo is a single tattoo or a layer pair with the single tattoo as a main part; The dividing module is used for transversely dividing the sheet sample along the layer-following direction of the target grain layer to obtain a first sub-sheet sample, a second sub-sheet sample and a third sub-sheet sample; The combined measurement module is used for combining the effective pore volume of the high-pressure helium gas and the pore volume of the nuclear magnetic fluid based on the first sub-sheet sample in an original state so as to obtain the total porosity of the target stratum; The quantitative-imaging analysis module is used for carrying out in-situ micro-area quantitative-imaging analysis based on the second sub-sheet sample by combining multi-scale optics with an electron microscope to obtain macroscopic information and microscopic information of the organic-inorganic components and the pore structure integration of the target tattoo; And the geochemical quantitative analysis module is used for carrying out geochemical quantitative analysis based on the third sub-sheet sample to acquire the organic matter abundance and oil content data of the target tattoo.

Description

Shale heterogeneity microscale fine characterization method and system Technical Field The invention belongs to the technical field of shale exploration, and particularly relates to a shale heterogeneity microscale fine characterization method and system. Background The quality shale reservoir is the core of shale oil and gas exploration and development, and reservoir quality evaluation always runs through the whole process of exploration and development. Shale reservoirs have strong heterogeneity and are mainly controlled by the structures and combination types of the layers, including organic-inorganic components and microcosmic structures in the layers, different scales and different types of layer combination characteristics and the like, which not only cause large difference of reservoir quality and oil-gas-bearing property, but also influence the enrichment state and fluidity of crude oil, so that the difficulty of predicting distribution of high-quality reservoirs and desserts is high, and the shale reservoirs are particularly important in the development of thin-ultrathin layer sections with high density millimeter-micrometer scale. Shale reservoirs generally have the characteristics of low pore size, low permeability, complex composition and structure and the like, and the traditional reservoir evaluation experimental technique method is not fully applicable. At present, experimental techniques such as a scanning electron microscope, a gas (helium) method, a liquid (mercury injection) method, a nuclear magnetic resonance method and the like are mainly adopted to obtain information such as a micro-pore structure and a mineral component required by shale reservoir evaluation, but the information still has a plurality of limitations. The method comprises the steps of 1) mainly detecting effective porosities which are not occupied by fluids and are communicated with each other in a sample by a helium injection method, wherein the total porosity can be detected only by preprocessing the fluids (such as wash oil and drying) in the fluid-containing (oil and water) sample, but the shale reservoir has the problem that the retained fluids are difficult to remove all the time, such as the oil-containing sample, wash oil solvents are not easy to enter and not exit, and the problem also exists when the porosities are measured by the liquid injection method, and particularly, the solvents are easy to react or adsorb with organic matters, clay minerals and the like in the sample, secondary pollution is generated, and the analysis quality is directly influenced. The nuclear magnetic resonance method mainly detects the porosity occupied by the hydrogen-containing fluid (oil and water), can not detect the pore part which is not filled by the fluid, and can only obtain the total porosity by detecting the sample after the hydrogen-containing fluid is saturated and all pores are filled, but the problem of 'no advance' still exists in the fluid saturation, the sample is easily damaged after the fluid is soaked in the fluid under high pressure for a long time, and the soaked fluid reacts with kerogen and clay minerals or adsorbs the like, so that the experimental result is still influenced. The scanning electron microscope can obtain microstructure information through high-resolution imaging, but the observation view field is tiny, the representative problem is always lacking, the type of organic matters is difficult to identify, and the organic microscopic component characteristics such as the type, the distribution, the pore development degree and the like of the organic matters have important influences on the occurrence state, the aggregation degree and the flowability of shale oil gas. Therefore, two problems are needed to be solved, namely, how to effectively connect the microcosmic and macroscopic, how to effectively express the microcosmic information of the scanning electron microscope in a macroscopic manner by using a technical approach, and how to combine the analysis of organic microcomponents under different optical (partial reflection and fluorescence) conditions with the scanning electron microscope, so as to realize in-situ quantitative-multiscale imaging of organic and inorganic compositions, pores and microcracks in a designated area (micro-area). At present, shale reservoir sampling still continues the traditional sampling mode and experimental technical standards, such as collecting standard plunger sample analytical properties with the diameter phi of 1 inch (25.4 mm) or phi of 1.5 inches (38 mm), collecting more than tens of grams of samples for geochemistry, sheet and electron microscope analysis and the like, and for thin-ultra-thin layers (single-layer thickness <1cm, mm-mum-level layers), the samples belong to mixed samples, and the internal components-textures and different layer structures and types of the single layers are difficult to finely characterize. Then, how to break through the trad