CN111749679B - Method and device for determining shale gas reservoir enrichment time node - Google Patents
Method and device for determining shale gas reservoir enrichment time node Download PDFInfo
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- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
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- E—FIXED CONSTRUCTIONS
- E21—EARTH OR ROCK DRILLING; MINING
- E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
- E21B49/00—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells
- E21B49/02—Testing the nature of borehole walls; Formation testing; Methods or apparatus for obtaining samples of soil or well fluids, specially adapted to earth drilling or wells by mechanically taking samples of the soil
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Abstract
The invention provides a method and a device for determining an enrichment time node of a shale gas reservoir, wherein the method for determining the enrichment time node of the shale gas reservoir comprises the following steps: collecting a shale gas reservoir sample, wherein the shale gas reservoir sample comprises carbonate mineral vein bodies which have the same development period as the shale gas reservoir enrichment period; according to the shale gas reservoir sample, manufacturing shale rock slices with different thicknesses, wherein the shale rock slices comprise carbonate mineral vein bodies; determining formation phase sub-bands contained in the shale rock slices according to multiple-phase secondary growth characteristics of carbonate mineral vein bodies; selecting a test area according to the element scanning analysis result of the forming period secondary belt; and carrying out isotope tests of uranium elements and lead elements on the test area, and obtaining shale gas reservoir enrichment time nodes based on isotope test results. The method and the device can improve the determination precision of the shale gas reservoir enrichment time node.
Description
Technical Field
The invention relates to the technical field of shale gas, in particular to a method and a device for determining an enrichment time node of a shale gas reservoir.
Background
The shale gas reservoir is formed in shale rich in organic matters and laminated argillaceous siltstone thereof, is a continuous gas reservoir which is self-generated and self-stored, and is one of main energy sources in China. In order to better understand the formation mechanism of the shale gas reservoir and facilitate exploration and exploitation of the shale gas reservoir, it is necessary to determine an enrichment time node of the shale gas reservoir.
At present, a hydrocarbon generation history simulation method based on buried history simulation and ancient temperature evolution history simulation is generally adopted for determining the shale gas reservoir enrichment time node, namely the history of generated oil and natural gas experienced by a stratum is simulated according to the characteristics that organic matters experience an early oil generation stage, a middle oil generation stage, a late oil generation stage and a main gas generation stage sequentially along with the temperature rise. The method comprises the steps of simulating a stratum burying process through the bottom-up stacking condition of the stratum and the thickness of the stripped stratum represented by an unconformity surface, wherein the burial history simulation is used for simulating the ancient temperature evolution process of the stratum through the bottom-up stacking condition of the stratum and the ancient temperature evolution history simulation is used for simulating the ancient temperature evolution of the stratum which is continuously buried and sunk or stripped and lifted along with the time according to the ancient temperature scale for recording the highest temperature experienced by the stratum. However, in the method for determining the shale gas reservoir enrichment time node, when the reservoir history is simulated, for the degraded stratum which is lifted in multiple periods, as the degraded stratum disappears, the thickness of the degraded stratum can be estimated only through other indirect evidences, but different indirect evidences are often greatly different; for the ancient temperature evolution history simulation, because the temperature recorded by the ancient temperature scale is the highest temperature experienced by the stratum and the temperature characteristics of the stratum before reaching the highest temperature and the temperature history after reaching the highest temperature are lacked, the shale gas reservoir enrichment time node determined based on the burial history simulation and the ancient temperature evolution history simulation has large uncertainty and can be usually only indirectly limited in one or several generations (the generation is a time unit representing the geological age, and the representative time length is usually tens of years or tens of millions of years), so that the accuracy of the determined shale gas reservoir enrichment time node is low.
Disclosure of Invention
In view of this, the present invention provides a method and an apparatus for determining a shale gas reservoir enrichment time node, so as to improve the determination accuracy of the shale gas reservoir enrichment time node.
In a first aspect, an embodiment of the present invention provides a method for determining a shale gas reservoir enrichment time node, including:
collecting a shale gas reservoir sample, wherein the shale gas reservoir sample comprises carbonate mineral vein bodies which have the same development period as the shale gas reservoir enrichment period;
according to the shale gas reservoir sample, manufacturing shale rock slices with different thicknesses, wherein the shale rock slices comprise carbonate mineral vein bodies;
determining formation phase sub-bands contained in the shale rock slices according to multiple-phase secondary growth characteristics of carbonate mineral vein bodies;
selecting a test area according to the element scanning analysis result of the forming period secondary belt;
and carrying out isotope tests of uranium elements and lead elements on the test area, and obtaining shale gas reservoir enrichment time nodes based on isotope test results.
In combination with the first aspect, the present embodiments provide a first possible implementation manner of the first aspect, where the collecting a shale gas reservoir sample includes:
selecting an initial pulse body which is vertical or parallel to the shale grain layer and has the grain layer dislocation within a preset dislocation degree from the well drilling rock core or the field exposed head;
and determining carbonate mineral vein bodies from the initial vein bodies according to the physical characteristic properties of calcite to obtain the shale gas reservoir sample.
With reference to the first possible implementation manner of the first aspect, the present examples provide a second possible implementation manner of the first aspect, where after the determining the carbonate mineral vein from the initial vein, before obtaining the shale gas reservoir sample, the method further includes:
if the determined carbonate mineral vein bodies come from the well drilling core, selecting the carbonate mineral vein bodies which are cut through and contain complete and non-broken shale core sections with the length exceeding a preset length threshold value from all the carbonate mineral vein bodies to obtain the shale gas reservoir sample;
and if the determined carbonate mineral vein bodies come from field outcrop, selecting the carbonate mineral vein bodies with the size not smaller than a preset size threshold value from all the carbonate mineral vein bodies to obtain the shale gas reservoir sample.
In combination with the first aspect, an embodiment of the present invention provides a third possible implementation manner of the first aspect, where the making of shale rock slices with different thicknesses according to the shale gas reservoir sample includes:
cutting a shale slice with a central carbonate mineral vein and a preset first thickness threshold along a direction vertical to the plane of the carbonate mineral vein and the layer surface of the shale grain;
and continuously manufacturing a fixed-year slice with a preset second thickness threshold, a parcel slice with a preset third thickness threshold and a common slice with a preset fourth thickness threshold according to the shale slices.
In combination with the third possible implementation manner of the first aspect, the present invention provides an example of the fourth possible implementation manner of the first aspect, wherein the determining the formation phase secondary zone included in the shale rock slices according to the multiple-phase secondary growth characteristics of the carbonate mineral vein includes:
acquiring general appearance information of a common slice and characteristic information of carbonate mineral crystals by using a polarization microscope;
taking a full-area photograph of the common slices, and dividing initial formation period sub-bands contained in the shale rock slices according to the acquired general picture information and the characteristic information of carbonate mineral crystals;
based on the division of the initial formation period sub-bands of the shale rock slices, selecting a to-be-corrected period sub-band with few surrounding rock particles, complete development of carbonate mineral crystals and good development from the initial formation period sub-bands corresponding to the fixed-year slices, performing cathodoluminescence photography by using a cathodoluminescence microscope, and subdividing the to-be-corrected period sub-band according to a photography result to obtain a sub-fractional formation period sub-band;
the formation period sub-band is obtained based on a sub-formation period sub-band and an initial formation period sub-band other than the to-be-corrected period sub-band.
With reference to the first aspect, an embodiment of the present invention provides a fifth possible implementation manner of the first aspect, where the selecting a test area according to an element scan analysis result of the formation period sub-band includes:
performing element scanning analysis on the forming period subband by using a laser ablation inductively coupled plasma mass spectrometer to obtain the content of uranium elements and the content of lead elements;
calculating the element ratio of the uranium element content to the lead element content;
and selecting a region with the element ratio exceeding a ratio threshold value and the content of the common lead element being lower than a content threshold value to obtain the test region.
In combination with the first aspect, the present embodiments provide a sixth possible implementation manner of the first aspect, where, after the determining of the formation-phase secondary zone included in the shale rock thin slab according to the multiple-phase growth characteristics of the carbonate mineral vein, before selecting the test area according to the element scan analysis result of the formation-phase secondary zone, the method further includes:
sampling the formation period sub-band aiming at the carbonate mineral vein in each formation period sub-band contained in the shale rock slice, and carrying out isotope test of carbon element, oxygen element and strontium element and rare earth element test on the sampling to obtain a sampling test result of the formation period sub-band; and obtaining isotope test results of carbon elements, oxygen elements and strontium elements and rare earth element test results of the surrounding rock, determining whether the carbonate mineral vein body in the formation period sub-band is from the surrounding rock or not based on the sampling test results, the isotope test results and the rare earth element test results, and excluding the formation period sub-band if the carbonate mineral vein body is not from the surrounding rock.
In a second aspect, an embodiment of the present invention further provides an apparatus for determining a shale gas reservoir enrichment time node, including:
the sample collection module is used for collecting a shale gas reservoir sample, and the shale gas reservoir sample contains carbonate mineral vein bodies which have the same development period with the shale gas reservoir enrichment period;
the sample manufacturing module is used for manufacturing shale rock slices with different thicknesses according to the shale gas reservoir sample, and the shale rock slices comprise carbonate mineral vein bodies;
a stage determining module for determining a formation stage sub-band contained in the shale rock slices according to a multiple stage growth characteristic of a carbonate mineral vein;
the test area selection module is used for selecting a test area according to the element scan analysis result of the forming period subband;
and the time node determining module is used for carrying out isotope tests on uranium elements and lead elements in the test area and obtaining shale gas reservoir enrichment time nodes based on isotope test results.
In a third aspect, an embodiment of the present application provides a computer device, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor, and the processor implements the steps of the above method when executing the computer program.
In a fourth aspect, the present application provides a computer-readable storage medium, on which a computer program is stored, and the computer program, when executed by a processor, performs the steps of the method described above.
According to the method and the device for determining the shale gas reservoir enrichment time node, provided by the embodiment of the invention, a shale gas reservoir sample is collected, wherein the shale gas reservoir sample comprises carbonate mineral vein bodies which develop in the same period as the shale gas reservoir enrichment; according to the shale gas reservoir sample, manufacturing shale rock slices with different thicknesses, wherein the shale rock slices comprise carbonate mineral vein bodies; determining formation phase sub-bands contained in the shale rock slices according to multiple-phase secondary growth characteristics of carbonate mineral vein bodies; selecting a test area according to the element scanning analysis result of the forming period secondary belt; and carrying out isotope tests of uranium elements and lead elements on the test area, and obtaining shale gas reservoir enrichment time nodes based on isotope test results. Therefore, carbonate mineral vein bodies in the same period as the shale gas reservoir enrichment are collected from a well drilling rock core or a field outcrop, and the formation period sub-bands of the carbonate mineral vein bodies are divided, so that the shale gas reservoir enrichment time nodes corresponding to the formation period sub-bands are determined based on the carbonate mineral vein body cause analysis of the formation period sub-bands of the carbonate mineral vein bodies, and the determination precision of the shale gas reservoir enrichment time nodes can be effectively improved.
In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a schematic flow chart of a method for determining a shale gas reservoir enrichment time node according to an embodiment of the invention;
FIG. 2 is a schematic structural diagram of an apparatus for determining a shale gas reservoir enrichment time node according to an embodiment of the present invention;
fig. 3 is a schematic structural diagram of a computer device 300 according to an embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
According to the existing method for determining the shale gas reservoir enrichment time node based on the simulation of the burial history and the paleo-temperature evolution history, the thickness of the denuded stratum can be estimated only through other indirect evidences, different indirect evidences are often greatly different, meanwhile, the temperature recorded by the paleo-temperature scale is the highest temperature experienced by the stratum, and the temperature characteristic before the stratum reaches the highest temperature and the temperature history after the highest temperature are lacked, so that the shale gas reservoir enrichment time node determined according to the method has large span, large uncertainty and low precision. In the embodiment of the invention, the shale gas reservoir sample is collected from the drilling core or the field outcrop, and the shale reservoir sample comprises the carbonate mineral vein which develops in the same period as the shale gas reservoir enrichment, so that the shale gas reservoir enrichment time node is determined based on the carbonate mineral vein.
The embodiment of the invention provides a method and a device for determining an enrichment time node of a shale gas reservoir, which are described by the following embodiments.
Fig. 1 shows a schematic flow chart of a method for determining a shale gas reservoir enrichment time node according to an embodiment of the present invention. As shown in fig. 1, the method includes:
in the embodiment of the invention, as an optional embodiment, shale gas reservoir samples are collected from a drill core or a field outcrop.
In the embodiment of the invention, along with the increase of the buried depth of the shale gas or shale layer, the temperature is increased, kerogen in the shale is cracked to generate oil and natural gas which enter pores, and along with the increase of the temperature, pore fluid (formation water, oil and natural gas) in the shale is subjected to volume expansion, so that the pore pressure of the shale layer is increased, when the pore pressure is increased to a certain degree, the shale layer is cracked, the pore fluid enters cracks to release the pressure, and then the pore pressure is further accumulated until the next crack. The cracking direction of the shale layer is parallel to the direction of the maximum effective principal stress and perpendicular to the direction of the minimum effective principal stress, and the cracking direction of the shale layer is perpendicular to the direction of the maximum effective principal stress. When the shale layer is cracked, the quartz or carbonate mineral crystals are crystallized to form carbonate mineral vein, and the opening-crystallization is carried out for a plurality of times in the same cracking, so that the carbonate mineral vein containing the carbonate mineral crystals with multi-stage crystallization is formed. Petroleum, natural gas, formation water and the like enter the carbonate mineral crystals to form inclusions in each crystallization, so that the temperature and pressure information at the time is recorded, and the shale gas reservoir enrichment time node can be accurately reflected.
In the embodiment of the invention, kerogen in the shale layer is cracked to generate oil and natural gas relative to the vein formed by other tectonic movements, and the carbonate mineral vein formed by the pore pressure rise of the shale gas reservoir caused by the oil and the natural gas has the following properties:
perpendicular or parallel to horizontally developing striated layers in the shale layer;
the pulse body becomes thinner upwards and downwards and disappears;
the stratum on the left and right sides of the pulse body do not have dislocation.
Thus, as an alternative embodiment, a shale gas reservoir sample is collected, comprising:
selecting an initial pulse body which is vertical or parallel to the shale grain layer and has the grain layer dislocation within a preset dislocation degree from the well drilling rock core or the field exposed head;
and determining carbonate mineral vein bodies from the initial vein bodies according to the physical characteristic properties of calcite to obtain the shale gas reservoir sample.
In the embodiment of the invention, the vertical carbonate mineral vein body formed by the pore pressure rise of the shale gas reservoir caused by oil and natural gas is inclined due to the structure movement, but the characteristic that the vein body direction is vertical or parallel to the shale grain layer is not changed, so that the initial vein body which is vertical or parallel to the shale grain layer and has no obvious dislocation (the dislocation of the grain layer is within the preset dislocation degree) is screened from the well drilling rock core or the field outcrop, and then the carbonate mineral vein body is screened from the initial vein body according to the physical characteristic property that calcite has cleavage and has hardness smaller than quartz.
In this embodiment of the present invention, as an optional embodiment, after the determining the carbonate mineral vein from the initial vein, before obtaining the shale gas reservoir sample, the method further includes:
if the determined carbonate mineral vein bodies come from the well drilling core, selecting the carbonate mineral vein bodies which are cut through and contain complete and non-broken shale core sections with the length exceeding a preset length threshold value from all the carbonate mineral vein bodies to obtain the shale gas reservoir sample;
and if the determined carbonate mineral vein bodies come from field outcrop, selecting the carbonate mineral vein bodies with the size not smaller than a preset size threshold value from all the carbonate mineral vein bodies to obtain the shale gas reservoir sample.
In the embodiment of the present invention, as an optional embodiment, the preset length threshold is 5 centimeters (cm), and the preset size threshold is: length, width, height 9 cm 6 cm 3 cm. Aiming at a well drilling core, selecting a complete and non-broken shale core section which is cut through by a vein body and has a length of more than 5 centimeters as a shale gas reservoir sample for subsequent analysis; for field outcrop, the size of the collected shale gas reservoir sample is not less than 9 cm x 6 cm x 3 cm, so that the extending height of the vein body in the direction vertical to the shale striation layer is not less than 9 cm, and the extending width in the direction parallel to the striation layer is not less than 6 cm in the shale gas reservoir sample.
102, according to the shale gas reservoir sample, manufacturing shale rock slices with different thicknesses, wherein the shale rock slices comprise carbonate mineral vein bodies;
in the embodiment of the invention, shale rock slices with different thicknesses and containing carbonate mineral veins are respectively manufactured according to shale gas reservoir samples.
In an embodiment of the present invention, as an optional embodiment, the manufacturing of shale rock slices with different thicknesses according to the shale gas reservoir sample includes:
cutting a shale slice with a central carbonate mineral vein and a preset first thickness threshold along a direction vertical to the plane of the carbonate mineral vein and the layer surface of the shale grain;
and continuously manufacturing a fixed-year slice with a preset second thickness threshold, a parcel slice with a preset third thickness threshold and a common slice with a preset fourth thickness threshold according to the shale slices.
In the embodiment of the present invention, as an optional embodiment, the first thickness threshold is 1 cm, the second thickness threshold is greater than the third thickness threshold, and the third thickness threshold is greater than the fourth thickness threshold. As an optional embodiment, the thickness of the fixed-year slice is 100 micrometers (um), the thickness of the wrapping body slice is 70 micrometers, the thickness of the common slice is 30 micrometers, and the fixed-year slice, the wrapping body slice and the common slice are all subjected to double-side polishing treatment and have the same cross-sectional area.
In the embodiment of the invention, as an optional embodiment, according to the characteristic that the carbonate mineral vein is formed once or grows and thickens for multiple times in a multiple period in a direction vertical to the shale grain layer, a shale slice with the thickness of about 1 cm and centered on the carbonate mineral vein is cut along a direction vertical to the plane of the carbonate mineral vein and vertical to the shale grain layer, and double-sided polishing slices with vein shale thicknesses of 100 μm, 70 μm and 30 μm are continuously manufactured on the basis of the shale slice and are respectively used as a dating slice, a wrapping slice and a common slice of a sheet for a multi-receiving laser ablation inductively coupled plasma mass spectrometer (LA-MC-ICP-MS).
103, determining a formation period sub-zone contained in the shale rock slice according to the multiple-stage growth characteristics of the carbonate mineral vein;
in the embodiment of the invention, the formation period sub-zone of carbonate mineral crystals contained in the shale rock slices is determined according to the multiple-period growth characteristics of the carbonate mineral vein. As an alternative embodiment, determining the formation phase sub-bands contained in the shale rock slices according to a multiple-phase growth characteristic of a carbonate mineral vein comprises:
a11, acquiring the general picture information of the common flake and the characteristic information of the carbonate mineral crystal by using a polarization microscope;
in the embodiment of the invention, a common sheet with the thickness of 30 mu m is observed under a common polarization microscope, the structure and sedimentary lamina characteristics of the shale are identified, and the alignment condition of laminae at two sides of a carbonate mineral vein and the contact characteristics of the carbonate mineral vein and the shale are analyzed. As an alternative embodiment, the multiple stage growth features include: profile information and feature information, wherein the profile information includes but is not limited to: the method comprises the following steps of (1) structural information, sedimentary striation characteristic information, striation alignment information on two sides of a carbonate mineral vein and contact characteristic information of the carbonate mineral vein and a shale rock slice; the characteristic information includes but is not limited to: the shape of the carbonate mineral crystal, the size of the carbonate mineral crystal, the surrounding rock particles and the change information of the inclusion in the carbonate mineral crystal from the surrounding rock to the central line of the vein body can determine the growth condition of the carbonate mineral crystal in the carbonate mineral vein body, namely the growth condition of the carbonate mineral crystal from the surrounding rock to the central line of the vein body or the growth condition of the carbonate mineral crystal from the central line of the vein body to the back of the surrounding rock.
A12, taking a full-area photograph of the common slices, and dividing initial formation period secondary zones contained in the shale rock slices according to the acquired profile information and the characteristic information of carbonate mineral crystals;
in the embodiment of the invention, because the single visual field under the polarizing microscope is limited, only the local part of the carbonate mineral vein can be observed, and the carbonate mineral vein is not beneficial to the whole analysis, after the growth characteristics of the general slice are acquired for multiple periods by using the polarizing microscope, the whole analysis and the division of the initial formation period subband are carried out on the general slice according to the acquired growth characteristics of the multiple periods by using the full-area photography. And dividing the regions with the same or similar growth characteristics (the error is smaller than a preset error threshold) into the same initial forming period sub-band.
A13, based on the division of the initial forming period sub-bands of the shale rock slices, selecting a to-be-corrected period sub-band with few surrounding rock particles and good development of carbonate mineral crystals from the initial forming period sub-bands corresponding to the fixed-year slices, performing cathodoluminescence photography by using a cathodoluminescence microscope, and subdividing the to-be-corrected period sub-band according to a photography result to obtain a sub-partial forming period sub-band;
in the embodiment of the invention, the annual slice of 100 mu m is observed under a cathode luminescence microscope, the initial formation period sub-band of a common slice is divided into a guide, the initial formation period sub-band with few surrounding rock particles, complete carbonate mineral crystal development and good development is preferably selected from the annual slice and the inclusion slice as the period sub-band to be corrected, and cathode luminescence observation photography is carried out.
In the embodiment of the invention, the carbonate mineral vein is easy to recrystallize, so that the original boundary and appearance of the carbonate mineral crystal cannot be identified under a polarizing microscope, and the accuracy of the subband in the initial forming period divided based on the polarizing microscope is not high.
In the embodiment of the invention, the cathodoluminescence color and brightness of the carbonate mineral crystal are mainly related to the relative contents of iron (Fe) and manganese (Mn) elements, and the contents of Fe and Mn are related to the oxidation-reduction property of the ancient fluid, so that the carbonate mineral crystal in different formation periods has different luminescence conditions under a cathode luminescence microscope due to recrystallization, and the luminescence condition of the carbonate mineral crystal in the formation period can be obtained by selecting the formation period to be corrected from the formation period and utilizing cathodoluminescence photography, thereby identifying the actual boundary of the carbonate mineral crystal according to the luminescence condition of the carbonate mineral crystal in the cathodoluminescence photography result, thereby achieving accurate subdivision of the to-be-corrected session sub-band based on the identified actual boundary.
A14, obtaining the formation period sub-band based on the minor formation period sub-band and the initial formation period sub-band other than the to-be-corrected period sub-band.
In an embodiment of the present invention, the formation period zone contained in the shale rock laminate comprises: a secondary formation-period secondary band, an initial formation-period secondary band obtained by deleting a to-be-corrected-period secondary band from the initial formation-period secondary band.
104, selecting a test area according to the element scanning analysis result of the forming period secondary belt;
in an embodiment of the present invention, as an optional embodiment, selecting a test area according to an element scan analysis result of the forming period sub-band includes:
performing element scanning analysis on the forming period subband by using a laser ablation inductively coupled plasma mass spectrometer to obtain the content of uranium (U) and lead (Pb);
calculating the element ratio of the uranium element content to the lead element content;
and selecting a region with the element ratio exceeding a ratio threshold value and the content of the common lead element being lower than a content threshold value to obtain the test region.
In the embodiment of the invention, after polishing and cleaning the fixed-year slices of 100 mu m to remove pollution, element in-situ scanning analysis (Mapping) is carried out on the forming-period secondary belt by using a laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) to obtain an element content or ratio distribution diagram, and then a region with high U/Pb but low common lead is selected as a test region according to the distribution.
In an embodiment of the present invention, as an optional embodiment, after determining a formation-period subband included in the shale rock thin slice according to a multiple-period growth characteristic of a carbonate mineral vein, before selecting a test area according to an element scan analysis result of the formation-period subband, the formation-period subband is screened to improve accuracy and reliability of a subsequent analysis, and therefore, the method further includes:
sampling the formation period sub-band aiming at the carbonate mineral vein in each formation period sub-band contained in the shale rock slice, and carrying out isotope test of carbon element, oxygen element and strontium element and rare earth element test on the sampling to obtain a sampling test result of the formation period sub-band; and obtaining isotope test results of carbon elements, oxygen elements and strontium elements and rare earth element test results of the surrounding rock, determining whether the carbonate mineral vein body in the formation period sub-band is from the surrounding rock or not based on the sampling test results, the isotope test results and the rare earth element test results, and excluding the formation period sub-band if the carbonate mineral vein body is not from the surrounding rock.
In the embodiment of the invention, as an optional embodiment, a micro-drilling machine is used for carrying out C, O and Sr isotope and rare earth element test analysis on a drilling sample of each forming period sub-band on a fixed-year slice of 100 mu m, and carrying out comparison analysis with surrounding rocks, so as to determine the surrounding rock source attribute of the carbonate mineral crystal of each forming period sub-band, and if it is determined that the carbonate mineral vein body does not originate from the surrounding rocks, the forming period sub-band is excluded, namely the forming period sub-band does not participate in subsequent analysis.
In the embodiment of the invention, carbonate mineral vein bodies of different formation periods have different possibilities of sources, for example, the carbonate mineral vein bodies can be derived from hydrothermal liquid, atmospheric precipitation infiltration and the like besides the surrounding rock, but the carbonate mineral vein bodies of different sources comprise C, O and Sr isotopes, rare earth elements and the like with different characteristic contents. Therefore, by judging the source of the carbonate mineral vein, the carbonate mineral vein for determining the shale gas reservoir enrichment time node is ensured to be from the surrounding rock, namely the carbonate mineral vein is caused by pore pressure rising caused by oil and gas generation in the shale, so that the accuracy of determining the shale gas reservoir enrichment time node is further improved.
And 105, carrying out isotope test on uranium elements and lead elements in the test area, and obtaining shale gas reservoir enrichment time nodes based on isotope test results.
In the embodiment of the invention, the test area corresponding to each formation period subband corresponds to a shale gas reservoir enrichment time node. As an optional embodiment, performing isotope tests on uranium elements and lead elements in the test region, and obtaining shale gas reservoir enrichment time nodes based on isotope test results, includes:
aiming at a test area on a fixed-year slice of 100 mu m, utilizing a laser ablation multi-receiving inductively coupled plasma mass spectrometer (LA-MC-ICP-MS) or a laser ablation inductively coupled plasma mass spectrometer (LA-ICP-MS) to complete U, Pb isotope test to obtain isotope test data;
processing the isotope test data to obtain an isotope ratio;
and drawing a harmony map based on the isotope ratio to realize common lead correction and element fractionation effect correction, and calculating the age of a lower intersection point according to the harmony map to obtain the shale gas reservoir enrichment time node.
In the embodiment of the invention, as an optional embodiment, the original isotope test data is processed by using Iolite or similar software to obtain the isotope ratio, and the Tera-Wasserburg harmonic map drawing is carried out on Isoplot3.0 or similar software based on the isotope ratio and the lower intersection point age calculation is completed.
The method for determining the enrichment time node of the shale gas reservoir provided by the embodiment of the invention comprises the steps of collecting a shale gas reservoir sample, wherein the shale gas reservoir sample comprises a carbonate mineral vein body which develops in the same period as the shale gas reservoir enrichment; according to the shale gas reservoir sample, manufacturing shale rock slices with different thicknesses, wherein the shale rock slices comprise carbonate mineral vein bodies; determining formation phase sub-bands contained in the shale rock slices according to multiple-phase secondary growth characteristics of carbonate mineral vein bodies; selecting a test area according to the element scanning analysis result of the forming period secondary belt; and carrying out isotope tests of uranium elements and lead elements on the test area, and obtaining shale gas reservoir enrichment time nodes based on isotope test results. Therefore, carbonate mineral pulse bodies in the same period as the shale gas reservoir enrichment are collected from a well drilling core or a field outcrop, and the formation period sub-bands of the carbonate mineral pulse bodies are divided, so that the shale gas reservoir enrichment time nodes corresponding to the formation period sub-bands are determined based on the carbonate mineral pulse body cause analysis of the formation periods of the carbonate mineral pulse bodies, the precision of the shale gas reservoir enrichment time nodes calculated by the method is generally equivalent to the precision of the critical geological boundary ages of the stratum, the shale gas reservoir enrichment absolute age time points with high precision can be obtained, the shale gas reservoir enrichment absolute age time points are not more than ten to dozens of million years, and the determination precision of the shale gas reservoir enrichment time nodes is effectively improved. Furthermore, the common polarizing microscope and the cathode luminescence microscope are comprehensively utilized to complete the division of the formation period sub-band of the carbonate mineral crystal, so that the accuracy of the division of the formation period sub-band can be ensured. And moreover, a test area is optimized on the basis of LA-ICP-MS element scanning analysis, a high-precision LA- (MC/HC) -ICP-MS mode is selected to measure the U-Pb age of calcite, and high-precision age data (shale gas reservoir enrichment time nodes) are guaranteed. In addition, the method has the advantages of small required sample amount, simple sample preparation, suitability for analysis based on rare and precious drilling cores, rapidness (the analysis can be completed within several days generally), and capability of obtaining high-precision absolute age data for carbonate mineral crystals of different formation periods.
In an embodiment of the present invention, as an optional embodiment, after determining a formation-period subband included in the shale rock thin slice according to a multiple-period growth characteristic of a carbonate mineral vein, before selecting a test area according to an element scan analysis result of the formation-period subband, the method further includes:
sampling the formation period sub-band aiming at the carbonate mineral vein in each formation period sub-band contained in the shale rock slice, and carrying out isotope test of carbon element, oxygen element and strontium element and rare earth element test on the sampling to obtain a sampling test result of the formation period sub-band; and obtaining isotope test results of carbon elements, oxygen elements and strontium elements and rare earth element test results of the surrounding rock, determining whether the carbonate mineral vein body in the formation period sub-band is from the surrounding rock or not based on the sampling test results, the isotope test results and the rare earth element test results, and excluding the formation period sub-band if the carbonate mineral vein body is not from the surrounding rock.
In the embodiment of the invention, as an optional embodiment, a micro-drilling machine is used for carrying out C, O and Sr isotope and rare earth element test analysis on a drilling sample of each forming period sub-band on a fixed-year slice of 100 mu m, and carrying out comparison analysis with surrounding rocks, so as to determine the surrounding rock source attribute of the carbonate mineral crystal of each forming period sub-band, and if it is determined that the carbonate mineral vein body does not originate from the surrounding rocks, the forming period sub-band is excluded, namely the forming period sub-band does not participate in subsequent analysis.
In the embodiment of the invention, carbonate mineral vein bodies of different formation periods have different possibilities of sources, for example, the carbonate mineral vein bodies can be derived from hydrothermal liquid, atmospheric precipitation infiltration and the like besides the surrounding rock, but the carbonate mineral vein bodies of different sources comprise C, O and Sr isotopes, rare earth elements and the like with different characteristic contents. Therefore, by judging the source of the carbonate mineral vein, the carbonate mineral vein for determining the shale gas reservoir enrichment time node is ensured to be from the surrounding rock, namely the carbonate mineral vein is caused by pore pressure rising caused by oil and gas generation in the shale, so that the accuracy of determining the shale gas reservoir enrichment time node is further improved.
In this embodiment of the present invention, as an optional embodiment, the method further includes:
acquiring a structural evolution history of a region where the shale gas reservoir sample is located, and determining a shale gas reservoir enrichment time node based on a burial history simulation and an ancient temperature evolution history simulation;
and judging whether the shale gas reservoir enrichment time node obtained based on the isotope test result is in the shale gas reservoir enrichment time node determined based on the reservoir history simulation and the ancient temperature evolution history simulation, and if not, correcting the shale gas reservoir enrichment time node determined based on the reservoir history simulation and the ancient temperature evolution history simulation based on the structural evolution history and the shale gas reservoir enrichment time node obtained based on the isotope test result.
In the embodiment of the invention, the structural evolution history of a region where a well is drilled or exposed outdoors and hydrocarbon generation history simulation data used for buried history simulation and ancient temperature evolution history simulation are collected, the period of important continuous sedimentation and increased burial depth of the region are combed, whether all shale gas reservoir enrichment time nodes obtained by the embodiment of the invention can be classified into the hydrocarbon generation period obtained by hydrocarbon generation history simulation is analyzed, if not, whether the shale gas reservoir enrichment time nodes obtained based on isotope test results are reliable is determined according to the structural evolution history, for example, the stratum deposition age obtained from the structural evolution history is 100 ten thousand years by combining with regional geological backgrounds (continuous sedimentation and increased burial depth), the shale gas reservoir enrichment time nodes (pulse age) obtained based on isotope test results is 200 ten thousand years, and in practical application, the shale gas reservoir enrichment time nodes obtained based on isotope test results are later than the stratum deposition age, therefore, the shale gas reservoir enrichment time node obtained based on the isotope test result is unreliable; if the reliability is high, for example, the stratum deposition age obtained from the structural evolution history is 100 ten thousand years, and the shale gas reservoir enrichment time node (pulse body age) obtained based on the isotope test result is 35 ten thousand years, the shale gas reservoir enrichment time node obtained based on the isotope test result is considered to be reliable, and if the hydrocarbon generation period obtained based on the hydrocarbon generation history simulation has two periods, respectively 80-90 ten thousand years and 50-60 ten thousand years, the shale gas reservoir enrichment time node obtained based on the isotope test result is used for correcting the hydrocarbon generation period, and the hydrocarbon generation period is adjusted to be 35 ten thousand years.
In the embodiment of the invention, the shale gas is generated after the generation of the crude oil in time sequence, or the kerogen is directly generated or the crude oil in the shale is cracked into gas, therefore, for the carbonate mineral crystals in different formation period sub-bands of the carbonate mineral vein body, the carbonate mineral crystals of the inclusion body containing the asphalt are caused by the increase of the pore fluid pressure caused by the early generation of the crude oil, and the formation period sub-bands of the inclusion body containing the gas (methane) and the inclusion body containing the liquid (brine) are formed simultaneously with the enrichment of the shale gas reservoir in the later period. Therefore, based on the shale gas reservoir enrichment time node, the fluid pressure and the temperature value obtained by calcite of different formation periods of the sub-bands, a plurality of accurate key time nodes for shale gas reservoir enrichment and the pore pressure and the formation temperature at the time can be given. As another alternative embodiment, the method further comprises:
a21, determining inclusion types and inclusion characteristic information contained in different formation periods of the shale rock slices;
in the embodiment of the invention, a microscopic laser Raman spectrometer is used for determining inclusion types and inclusion characteristic information contained in shale rock slices of 100 μm and 70 μm in different formation periods, wherein the inclusion types include but are not limited to: an inclusion containing bitumen, an inclusion containing gas, and an inclusion containing liquid. For inclusions containing bitumen, the corresponding inclusion characteristic information includes: the pitch composition, the gas composition and the pressure of inclusion to the inclusion that contains gas, corresponding inclusion characteristic information includes: the composition and the pressure of inclusion to the inclusion that contains liquid, corresponding inclusion characteristic information includes: salinity and composition of inclusions and uniform temperature.
A22, utilizing a microscope equipped with a cold and hot table to measure the temperature of the inclusion, and obtaining the temperature and the pore pressure of the shale gas reservoir corresponding to the shale gas reservoir enrichment time node based on the inclusion temperature measurement and a preset pressure correction strategy.
In the embodiment of the invention, a shale rock slice with the thickness of 70 microns is taken down from a glass slide, a microscope with a cold and hot table is used for completing the temperature measurement of a corresponding fluid inclusion, and the fluid pressure and the temperature when carbonate mineral vein bodies are formed can be obtained through a preset pressure correction strategy, so that the fluid temperature and the fluid pressure when carbonate mineral crystals in different formation periods are formed can be obtained, and the temperature and the pore pressure of a shale oil gas reservoir corresponding to a shale gas reservoir enrichment time node are obtained. As an optional embodiment, a laser raman spectrometer may be used to obtain the displacements of raman scattering peaks of methane inclusion in different formation periods respectively, and the density of methane inclusion in each formation period is calculated according to a preset empirical formula; heating the carbonate mineral vein body by using a cold and hot platform of a microscope to obviously reduce and gradually disappear bubbles in a gas-liquid two-phase inclusion (the inclusion with a single phase when being captured), wherein when the temperature is raised to a single-phase temperature, the gas-liquid two phases coexist and are changed into the single phase, and the single-phase temperature is the uniform temperature of the inclusion, namely the capture temperature; and finally, acquiring the pressure of the methane inclusion according to the density and the uniform temperature of the methane inclusion based on the empirical relationship (pressure correction strategy) among the uniform temperature, the pressure and the density of the methane inclusion, so as to obtain the temperature and the pore pressure of the shale gas reservoir corresponding to different formation periods.
Fig. 2 shows a schematic structural diagram of an apparatus for determining a shale gas reservoir enrichment time node according to an embodiment of the present invention. As shown in fig. 2, the apparatus includes:
the sample collection module 201 is used for collecting a shale gas reservoir sample, wherein the shale gas reservoir sample contains carbonate mineral vein bodies which have the same development period as the shale gas reservoir enrichment period;
in the embodiment of the invention, as an optional embodiment, the sample collection module 201 selects an initial pulse which is vertical or parallel to a shale lamella and has lamella dislocation within a preset dislocation degree from a drill core or a field exposed head; and determining carbonate mineral vein bodies from the initial vein bodies according to the physical characteristic properties of calcite to obtain the shale gas reservoir sample.
In this embodiment of the present invention, as another optional embodiment, the sample collection module 201 is further configured to, after determining the carbonate mineral vein from the initial vein, before obtaining the shale gas reservoir sample:
if the determined carbonate mineral vein bodies come from the well drilling core, selecting the carbonate mineral vein bodies which are cut through and contain complete and non-broken shale core sections with the length exceeding a preset length threshold value from all the carbonate mineral vein bodies to obtain the shale gas reservoir sample;
and if the determined carbonate mineral vein bodies come from field outcrop, selecting the carbonate mineral vein bodies with the size not smaller than a preset size threshold value from all the carbonate mineral vein bodies to obtain the shale gas reservoir sample.
A sample preparation module 202, configured to prepare shale rock slices with different thicknesses according to the shale gas reservoir sample, where the shale rock slices include carbonate mineral vein bodies;
in this embodiment of the present invention, as an optional embodiment, the sample preparation module 202 includes:
a shale slice generating unit (not shown in the figure) for cutting a shale slice with a thickness of a preset first thickness threshold value and a center containing carbonate mineral vein along a direction vertical to the carbonate mineral vein plane and vertical to the shale grain layer plane;
and the sample generation unit is used for continuously manufacturing a fixed-year slice with a preset second thickness threshold, a parcel slice with a preset third thickness threshold and a common slice with a preset fourth thickness threshold according to the shale slices.
In the embodiment of the present invention, as an optional embodiment, the first thickness threshold is 1 cm, the perennial sheet thickness is 100 micrometers (um), the wrapper sheet thickness is 70 micrometers, and the common sheet thickness is 30 micrometers.
A stage determining module 203 for determining a formation stage sub-band included in the shale rock slices according to a plurality of stage growth characteristics of a carbonate mineral vein;
in this embodiment of the present invention, as an optional embodiment, the installment determining module 203 includes:
a polarization observation unit (not shown in the figure) for acquiring profile information of the general flake and characteristic information of the carbonate mineral crystal using a polarization microscope;
the full-area photographing unit is used for photographing the full area of the common sheet and dividing an initial formation period secondary zone contained in the shale rock sheet according to the acquired general profile information and the characteristic information of the carbonate mineral crystals;
the period sub-band dividing unit is used for selecting a to-be-corrected period sub-band with few surrounding rock particles and good development of carbonate mineral crystals from the initial formation period sub-bands corresponding to the fixed-year slices based on the division of the initial formation period sub-band of the shale rock slices, performing cathodoluminescence photography by using a cathodoluminescence microscope, and subdividing the to-be-corrected period sub-band according to a photography result to obtain a secondary formation period sub-band;
a formation period band determination unit configured to obtain the formation period band based on a minor formation period band and an initial formation period band other than the to-be-corrected period band.
A test area selection module 204, configured to select a test area according to the element scan analysis result of the forming period subband;
in this embodiment of the present invention, as an optional embodiment, the test area selecting module 204 includes:
an element scanning analysis unit (not shown in the figure) for performing element scanning analysis on the forming-period subband by using a laser ablation inductively coupled plasma mass spectrometer to obtain the content of uranium elements and the content of lead elements;
the element ratio calculation unit is used for calculating the element ratio of the uranium element content to the lead element content;
and the test area selection unit is used for selecting an area with the element ratio exceeding a ratio threshold and the content of the common lead element being lower than a content threshold to obtain the test area.
And the time node determining module 205 is configured to perform isotope testing on uranium elements and lead elements in the testing region, and obtain shale gas reservoir enrichment time nodes based on isotope testing results.
In this embodiment of the present invention, as an optional embodiment, the time node determining module 205 includes:
an isotope test data acquisition unit (not shown in the figure) configured to complete U, Pb isotope tests by using a laser ablation multi-reception inductively coupled plasma mass spectrometer or a laser ablation inductively coupled plasma mass spectrometer for a test area on a 100 μm perennial sheet, so as to obtain isotope test data;
the ratio calculation unit is used for processing the isotope test data to obtain an isotope ratio;
and the time node determining unit is used for drawing a harmonic graph based on the isotope ratio to realize common lead correction and element fractionation effect correction, and performing lower intersection point age calculation according to the harmonic graph to obtain the shale gas reservoir enrichment time node.
In this embodiment of the present invention, as an optional embodiment, the apparatus further includes:
a vein source processing module (not shown in the figure) for sampling the formation period sub-band, performing isotope test of carbon element, oxygen element and strontium element and rare earth element test on the sample, and obtaining a sample test result of the formation period sub-band, with respect to the carbonate mineral vein in each formation period sub-band included in the shale rock slice; and obtaining isotope test results of carbon elements, oxygen elements and strontium elements and rare earth element test results of the surrounding rock, determining whether the carbonate mineral vein body in the formation period sub-band is from the surrounding rock or not based on the sampling test results, the isotope test results and the rare earth element test results, and excluding the formation period sub-band if the carbonate mineral vein body is not from the surrounding rock.
In this embodiment of the present invention, as an optional embodiment, the apparatus further includes:
a time node correction module (not shown in the figure) for acquiring the structural evolution history of the region where the shale gas reservoir sample is located, and simulating and determining a shale gas reservoir enrichment time node based on the burial history simulation and the paleo-temperature evolution history; and judging whether the shale gas reservoir enrichment time node obtained based on the isotope test result is in the shale gas reservoir enrichment time node determined based on the reservoir history simulation and the ancient temperature evolution history simulation, and if not, correcting the shale gas reservoir enrichment time node determined based on the reservoir history simulation and the ancient temperature evolution history simulation based on the structural evolution history and the shale gas reservoir enrichment time node obtained based on the isotope test result.
As shown in fig. 3, an embodiment of the present application provides a computer device 300 for executing the method for determining a shale gas reservoir enrichment time node in fig. 1, the device includes a memory 301, a processor 302, and a computer program stored on the memory 301 and executable on the processor 302, wherein the processor 302 implements the steps of the method for determining a shale gas reservoir enrichment time node when executing the computer program.
Specifically, the memory 301 and the processor 302 can be general-purpose memory and processor, and are not limited to specific examples, and the processor 302 can execute the method for determining the shale gas reservoir enrichment time node when executing the computer program stored in the memory 301.
Corresponding to the method for determining the shale gas reservoir enrichment time node in fig. 1, an embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored, where the computer program is executed by a processor to perform the steps of the method for determining the shale gas reservoir enrichment time node.
In particular, the storage medium can be a general-purpose storage medium, such as a mobile disc, a hard disc, or the like, and when executed, the computer program on the storage medium can execute the method for determining the shale gas reservoir enrichment time node.
In the embodiments provided in the present application, it should be understood that the disclosed system and method may be implemented in other ways. The above-described system embodiments are merely illustrative, and for example, the division of the units is only one logical functional division, and there may be other divisions in actual implementation, and for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection of systems or units through some communication interfaces, and may be in an electrical, mechanical or other form.
The units described as separate parts may or may not be physically separate, and parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiment.
In addition, functional units in the embodiments provided in the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit.
The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer readable storage medium. Based on such understanding, the technical solution of the present application or portions thereof that substantially contribute to the prior art may be embodied in the form of a software product stored in a storage medium and including instructions for causing a computer device (which may be a personal computer, a server, or a network device) to execute all or part of the steps of the method according to the embodiments of the present application. And the aforementioned storage medium includes: various media capable of storing program codes, such as a usb disk, a removable hard disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), a magnetic disk, or an optical disk.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus once an item is defined in one figure, it need not be further defined and explained in subsequent figures, and moreover, the terms "first", "second", "third", etc. are used merely to distinguish one description from another and are not to be construed as indicating or implying relative importance.
Finally, it should be noted that: the above-mentioned embodiments are only specific embodiments of the present application, and are used for illustrating the technical solutions of the present application, but not limiting the same, and the scope of the present application is not limited thereto, and although the present application is described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: any person skilled in the art can modify or easily conceive the technical solutions described in the foregoing embodiments or equivalent substitutes for some technical features within the technical scope disclosed in the present application; such modifications, changes or substitutions do not depart from the spirit and scope of the present disclosure, which should be construed in light of the above teachings. Are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.
Claims (8)
1. A method for determining an enrichment time node of a shale gas reservoir, comprising:
collecting a shale gas reservoir sample, wherein the shale gas reservoir sample comprises carbonate mineral vein bodies which have the same development period as the shale gas reservoir enrichment period;
according to the shale gas reservoir sample, manufacturing shale rock slices with different thicknesses, wherein the shale rock slices comprise carbonate mineral vein bodies;
determining formation phase sub-bands contained in the shale rock slices according to multiple-phase secondary growth characteristics of carbonate mineral vein bodies;
selecting a test area according to the element scanning analysis result of the forming period secondary belt;
isotope tests of uranium elements and lead elements are carried out on the test area, and shale gas reservoir enrichment time nodes are obtained based on isotope test results;
according to the shale gas reservoir sample, shale rock slices with different thicknesses are manufactured, and the method comprises the following steps:
cutting a shale slice with a central carbonate mineral vein and a preset first thickness threshold along a direction vertical to the plane of the carbonate mineral vein and the layer surface of the shale grain;
according to the shale slices, fixed-year slices with a preset second thickness threshold, inclusion slices with a preset third thickness threshold and common slices with a preset fourth thickness threshold are continuously manufactured;
after the determining a formation phase sub-zone included in the shale rock slices according to the multiple-phase multiple growth characteristics of carbonate mineral veins, before selecting a test area according to an elemental scanning analysis result of the formation phase sub-zone, the method further comprises:
sampling the formation period sub-band aiming at the carbonate mineral vein in each formation period sub-band contained in the shale rock slice, and carrying out isotope test of carbon element, oxygen element and strontium element and rare earth element test on the sampling to obtain a sampling test result of the formation period sub-band; and obtaining isotope test results of carbon elements, oxygen elements and strontium elements and rare earth element test results of the surrounding rock, determining whether the carbonate mineral vein body in the formation period sub-band is from the surrounding rock or not based on the sampling test results, the isotope test results and the rare earth element test results, and excluding the formation period sub-band if the carbonate mineral vein body is not from the surrounding rock.
2. The method of claim 1, wherein collecting the shale gas reservoir sample comprises:
selecting an initial pulse body which is vertical or parallel to the shale grain layer and has the grain layer dislocation within a preset dislocation degree from the well drilling rock core or the field exposed head;
and determining carbonate mineral vein bodies from the initial vein bodies according to the physical characteristic properties of calcite to obtain the shale gas reservoir sample.
3. The method of claim 2, wherein after said determining carbonate mineral vein from said initial vein, and prior to obtaining said shale gas reservoir sample, said method further comprises:
if the determined carbonate mineral vein bodies come from the well drilling core, selecting the carbonate mineral vein bodies which are cut through and contain complete and non-broken shale core sections with the length exceeding a preset length threshold value from all the carbonate mineral vein bodies to obtain the shale gas reservoir sample;
and if the determined carbonate mineral vein bodies come from field outcrop, selecting the carbonate mineral vein bodies with the size not smaller than a preset size threshold value from all the carbonate mineral vein bodies to obtain the shale gas reservoir sample.
4. The method of claim 1, wherein determining the secondary bands of formation phases contained in the shale rock slices based on multiple growth characteristics of carbonate mineral veins comprises:
acquiring general appearance information of a common slice and characteristic information of carbonate mineral crystals by using a polarization microscope;
taking a full-area photograph of the common slices, and dividing initial formation period sub-bands contained in the shale rock slices according to the acquired general picture information and the characteristic information of carbonate mineral crystals;
based on the division of the initial formation period sub-bands of the shale rock slices, selecting a to-be-corrected period sub-band with few surrounding rock particles, complete development of carbonate mineral crystals and good development from the initial formation period sub-bands corresponding to the fixed-year slices, performing cathodoluminescence photography by using a cathodoluminescence microscope, and subdividing the to-be-corrected period sub-band according to a photography result to obtain a sub-fractional formation period sub-band;
the formation period sub-band is obtained based on a sub-formation period sub-band and an initial formation period sub-band other than the to-be-corrected period sub-band.
5. The method of claim 1, wherein selecting a test area based on the results of the elemental scan analysis of the formed session sub-band comprises:
performing element scanning analysis on the forming period subband by using a laser ablation inductively coupled plasma mass spectrometer to obtain uranium element content and lead element content distribution;
calculating the element ratio of the uranium element content to the lead element content;
and selecting a region with the element ratio exceeding a ratio threshold value and the content of the common lead element being lower than a content threshold value to obtain the test region.
6. An apparatus for determining a shale gas reservoir enrichment time node, comprising:
the sample collection module is used for collecting a shale gas reservoir sample, and the shale gas reservoir sample contains carbonate mineral vein bodies which have the same development period with the shale gas reservoir enrichment period;
the sample manufacturing module is used for manufacturing shale rock slices with different thicknesses according to the shale gas reservoir sample, and the shale rock slices comprise carbonate mineral vein bodies;
a stage determining module for determining a formation stage sub-band contained in the shale rock slices according to a multiple stage growth characteristic of a carbonate mineral vein;
the test area selection module is used for selecting a test area according to the element scan analysis result of the forming period subband;
the time node determining module is used for carrying out isotope tests on uranium elements and lead elements in the test area and obtaining shale gas reservoir enrichment time nodes based on isotope test results;
the sample preparation module comprises:
the shale slice generating unit is used for cutting a shale slice which contains a carbonate mineral vein body in the center and has a thickness of a preset first thickness threshold value along the direction vertical to the plane of the carbonate mineral vein body and the plane of the shale grain layer;
the sample generation unit is used for continuously manufacturing fixed-year slices with preset second thickness thresholds, inclusion slices with preset third thickness thresholds and common slices with preset fourth thickness thresholds according to the shale slices;
the vein body source processing module is used for sampling the formation period sub-bands aiming at carbonate mineral vein bodies in each formation period sub-band contained in the shale rock slices, and carrying out isotope test and rare earth element test on carbon elements, oxygen elements and strontium elements on the samples to obtain sampling test results of the formation period sub-bands; and obtaining isotope test results of carbon elements, oxygen elements and strontium elements and rare earth element test results of the surrounding rock, determining whether the carbonate mineral vein body in the formation period sub-band is from the surrounding rock or not based on the sampling test results, the isotope test results and the rare earth element test results, and excluding the formation period sub-band if the carbonate mineral vein body is not from the surrounding rock.
7. An electronic device, comprising: a processor, a memory and a bus, the memory storing machine readable instructions executable by the processor, the processor and the memory communicating over the bus when the electronic device is running, the machine readable instructions when executed by the processor performing the steps of the method of determining a shale gas reservoir enrichment time node as claimed in any of claims 1 to 5.
8. A computer-readable storage medium, having stored thereon a computer program which, when being executed by a processor, performs the steps of the method for determining a shale gas reservoir enrichment time node according to any one of claims 1 to 5.
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