Method for recovering maximum ancient ground temperature and regional thermal history of marine facies or lacustrine facies sedimentary area

Abstract

The invention provides a method for recovering the maximum ancient ground temperature and regional thermal history of a marine facies or lacustrine facies sedimentary area. The method comprises the following steps: (1) selecting a carbonate sample, and carrying out effectiveness analysis on the carbonate sample to obtain a hydrocarbon source rock maturity test sample and a paleo-thermal history research sample; (2) performing pretreatment on the hydrocarbon source rock maturity test sample and the paleo-thermal history research sample obtained in the step (1), and then performing carbonate cluster isotope composition analysis and data validity selection to obtain test data; and (3) recovering the paleo-temperature and / or regional thermal history according to the available data obtained in the step (2). According to the method, the maturity (suffered maximum paleo temperature) of marine facies / lacustrine facies hydrocarbon source rocks is recovered by utilizing a cluster isotope method of carbonate of a hydrocarbon source rock interlayer or an adjacent layer, and a large set of well preserved carbonate samples is used for a regional paleo thermal history recovery technology, so that a basis is provided for realizing oil and gas resource evaluation and aggregation rule prediction; the method is greatly helpful for exploration of shale oil and gas and deep / ultra-deep oil and gas.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas exploration, and in particular relates to a method for restoring the maximum paleo-geothermal temperature and regional thermal history of a marine or lacustrine sedimentary area. Background Art

[0002] Source rocks are the basis for oil and gas generation, and the amount of oil and gas generated is controlled by the maturity of source rocks. The maturity of source rocks is often used as an important means of restoring regional thermal history. Usually, the reflectivity of vitrinite in coal is the material basis for maturity measurement. However, marine / lake source rocks are mainly composed of algae and other substances, lacking vitrinite components of terrestrial origin, and there is no direct measurement technology.

[0003] At present, the commonly used methods for calibrating the maturity of source rocks include vitrinite reflectance measurement and soluble organic matter biomarker compound calibration. Soluble organic matter, such as aromatic hydrocarbon parameters, has many influencing factors, which are not only affected by maturity, but also by the sedimentary microenvironment. There is a lot of controversy in the maturity evaluation of source rocks.

[0004] The semi-quantitative method can use the pyrolysis TMax temperature, but this method has a certain reference value for the medium maturity stage. It has poor reliability and is generally not applicable to the low maturity stage or high maturity stage hydrocarbon source rocks; qualitative kerogen color and fluorescence, study the color changes of biological residues, such as the color of conodonts, spores, pollen, and algae. Another is to observe the color changes of kerogen. With the increase of maturity, the color of both changes from light to dark, from yellow to brown and black. Generally speaking, light yellow and yellow correspond to the immaturity and low maturity of organic matter, dark yellow-light brown (light brown) corresponds to the mature stage, and dark brown (dark brown)-black corresponds to over-maturity. Obviously, this method is a qualitative evaluation method and cannot be accurately used for comparison and quantitative evaluation of source rock maturity.

[0005] Vitrinite reflectance is often lacking in marine or lacustrine source rocks, resulting in the use of asphalt reflectance instead. Others use fluid inclusion temperature measurement methods to record the highest inclusion fluid temperature as the maximum paleotemperature experienced. These methods all have certain limitations. For example, the formation of asphalt is characterized by multiple stages. Asphalt in the same stage may have extremely strong anisotropy. In addition, asphalt is limited by geological and oil-generating conditions and may be relatively scarce in some areas, which has a lot of uncertainties. The comparability varies greatly between regions. Inclusion temperature measurement is limited to the formation stage of authigenic minerals, and mainly reflects the formation temperature of authigenic minerals or enlarged edges, rather than recording the temperature history experienced by the region, because authigenic minerals are not able to capture the inclusion conditions of each temperature.

[0006] However, marine / lake source rocks are mainly composed of algae and other substances, lacking terrestrial vitrinite components, and there is no direct measurement technology. Therefore, providing a technology for restoring the maturity of source rocks and regional thermal history in marine or lake sedimentary areas has become one of the problems that need to be solved in this field. Summary of the invention

[0007] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for restoring the maturity of source rocks and regional thermal history in marine or lacustrine sedimentary areas. The present invention uses the cluster isotope method of carbonates in the interlayer or adjacent layers of the source rock to restore the maturity (maximum paleotemperature suffered) and regional paleo-thermal history of marine / lacustrine source rocks, thereby providing a basis for the evaluation of oil and gas resources and the prediction of accumulation rules, which is of great help to shale oil and gas and deep / ultra-deep oil and gas exploration.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] The present invention provides a method for restoring the maturity of source rocks and regional thermal history in marine or lacustrine sedimentary areas, the method comprising the following steps:

[0010] (1) Select carbonate samples and conduct validity analysis on the carbonate samples to obtain maximum paleo-geothermal research samples and / or paleo-thermal history research samples;

[0011] (2) Pre-processing the maximum paleo-geothermal research samples and / or paleo-thermal history research samples obtained in step (1), and then performing carbonate cluster isotope composition analysis and data validity selection to obtain test data;

[0012] (3) Restore the maximum paleotemperature and / or regional thermal history based on the available data obtained in step (2).

[0013] The present invention mainly considers that carbonate or large carbonate strata cluster isotopes in marine and Hunan source rock interlayers can record the historical temperature of the stratum manager. The ancient temperature and / or regional thermal history are restored by carbonate sample selection principles, pre-treatment technology; different carbonate thermodynamic structure reorganization kinetic recovery technology; cluster isotope surface temperature and vitrinite maturity relationship model, etc.

[0014] As a preferred technical solution of the present invention, the selection in step (1) includes: selecting the maximum paleo-geothermal sample and the regional thermal history sample in the target area strata.

[0015] Preferably, the target area includes a region where calcite and dolomite are distributed simultaneously.

[0016] Preferably, the maximum paleo-geothermal sample comprises a carbonate interlayer sample in shale.

[0017] Preferably, the regional thermal history samples include large sets of original sedimentary thick-layer carbonate layer samples.

[0018] It is worth noting that the selection of appropriate carbonate samples mainly considers the macroscopic vertical and horizontal distribution characteristics of the target area. For the maximum paleo-geothermal temperature, carbonate interlayer samples in mudstone can be selected; regional thermal history research is mainly based on the original thick sedimentary large set of carbonate layer samples, and multiple sets of carbonate strata are sampled vertically and in multiple layers. If calcite and dolomite are distributed in the target area at the same time, the two carbonate minerals can be sampled at the same time. Multiple mineral types and multiple layers of strata are jointly defined, and the regional thermal history can be accurately restored.

[0019] As a preferred technical solution of the present invention, the maximum paleo-geothermal research samples in step (1) include micrite-microcrystalline limestone and dolomite samples with strong dissolution of mudstone interlayers and at least two stages of authigenic mineral filling.

[0020] Preferably, the purity of the maximum paleo-geothermal research sample exceeds 95%, for example, it can be 96%, 97%, 98% or 99%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the maximum paleo-geothermal research samples include carbonate rock samples with strong dissolution.

[0022] Preferably, the purity of the ancient thermal history research sample exceeds 85%, for example, it can be 88%, 90%, 92%, 94% or 96%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] Preferably, the samples for paleothermal history research include mud-crystal microcrystalline limestone and dolomite samples with weak cathode luminescence and weak dissolution.

[0024] It is worth noting that the requirements for samples for the two purposes of maximum paleo-geothermal temperature and regional thermal history are completely different. The samples selected for maximum paleo-geothermal temperature must be guaranteed to have been strongly affected during the maximum paleo-geothermal period, that is, evidence of the development and activity of diagenetic fluids such as strong multi-stage dissolution and cementation can be seen in carbonate minerals. Dissolution pores can be seen in carbonate interlayers, and precipitated cemented authigenic minerals can be seen everywhere. On the contrary, samples used for regional thermal history restoration should avoid being strongly affected by fluids as much as possible, and should be mainly mud crystal or powder crystal carbonate minerals.

[0025] The samples were subjected to thin section identification, cathode luminescence experiment and XRD tests. For the former, samples of micrite microcrystalline limestone and dolomite with strong dissolution, multiple stages of authigenic mineral filling, and calcite or dolomite purity exceeding 85% were selected. For the latter, samples of micrite microcrystalline limestone and dolomite with weak cathode luminescence, weak dissolution, and calcite or dolomite purity exceeding 95% were selected, avoiding cracks and filling zones.

[0026] As a preferred technical solution of the present invention, the sample pretreatment in step (2) includes maximum paleo-geothermal research sample pretreatment and paleo-thermal history research sample pretreatment.

[0027] Preferably, the sample pre-treatment for the source rock maturity test comprises: drilling with a dental drill, grinding, washing with hydrogen peroxide, washing with water and drying the maximum paleo-geothermal research sample in sequence.

[0028] Preferably, the grinding is used to separate organic matter components.

[0029] Preferably, the concentration of the hydrogen peroxide is 3-5wt%, for example, 3.2wt%, 3.4wt%, 3.6wt%, 3.8wt%, 4.0wt%, 4.2wt%, 4.4wt%, 4.6wt% or 4.8wt%, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0030] Preferably, the water washing is performed 3 to 5 times, for example, 3 times, 4 times or 5 times.

[0031] Preferably, the drying temperature is 30-50° C., for example, 34° C., 38° C., 42° C. or 46° C., but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0032] Preferably, the drying time is 10 to 15 hours, for example, 11 hours, 12 hours, 13 hours or 14 hours, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] As a preferred technical solution of the present invention, the paleothermal history research sample pretreatment comprises: grinding the paleothermal history research sample;

[0034] Preferably, the particle size of the sample after the grinding process is not less than 80 mesh, for example, it can be 90 mesh, 100 mesh or 110 mesh, but it is not limited to the listed values, and other values ​​not listed in the numerical range are also applicable.

[0035] It is worth noting that the mud shale interlayer samples used for the maximum paleo-geothermal study often contain a lot of organic matter, which will lead to extremely inaccurate carbonate cluster isotope measurements, and even cause the analysis and testing system to crash and paralyze. Removing organic matter without destroying the isotope structure of carbonate clusters is the key to obtaining reliable data. Micro-drilling is used to obtain core samples to artificially avoid interference from organic matter including kerogen and asphalt. After the sample is ground, flotation and other methods are used to physically separate the organic components. Then, 3% hydrogen peroxide is used to remove residual organic matter, and then it is washed with distilled water for 3 to 5 times and dried in an oven at 30 to 50°C for 10 to 15 hours. Test and analyze the organic carbon content, preferably below the detection line.

[0036] For large sets of carbonate samples used for thermal history research, the organic matter content is generally lacking, except for the possible presence of asphalt. Avoid cracks and filling zones, avoid asphalt, use a micro drill to drill samples, grind them, and then conduct analytical testing.

[0037] As a preferred technical solution of the present invention, the carbonate cluster isotope composition analysis in step (2) comprises: using an instrument to independently measure Δ 47 value, and the carbonate δ 13 C and δ 18 O.

[0038] As a preferred technical solution of the present invention, the data validity selection in step (2) includes: performing standard deviation analysis on the test data;

[0039] Preferably, the standard deviation analysis includes single sample analysis and comprehensive comparative analysis of series of samples.

[0040] As a preferred technical solution of the present invention, the single sample analysis includes: analyzing the results of 7 to 10 times obtained from a single measurement, and the screening principle is based on δ 13 C and δ 18 O analysis mean square error does not exceed 0.01, Δ 47 The mean square error is no more than 0.05, which is considered valid. Then the results are compared three times, and the average absolute error does not exceed 10%.

[0041] For a comprehensive comparative analysis of a series of samples, consider the relationship between the sample and other samples in the profile position. For example, samples of the same type and layer generally have similar Δ 47 Data from the older time scale should have a smaller Δ than the upper one. 47 value, and use this as a principle to screen out individual invalid samples.

[0042] As a preferred technical solution of the present invention, the method for paleotemperature recovery in step (3) includes: measuring the surface temperature corresponding to carbonate cluster isotopes to reflect the maximum paleotemperature.

[0043] As a preferred technical solution of the present invention, the method for recovering the regional thermal history in step (3) includes: based on the calculation of the solid-state rearrangement structural reorganization kinetics of carbonate cluster isotopes, taking advantage of the different crystallization kinetics characteristics of calcite and dolomite.

[0044] Furthermore, although calcite and dolomite have experienced the same thermal history, they show different evolutionary trends. Dolomite has a strong temperature lock effect. As the burial depth and temperature increase, the solid-state rearrangement amplitude is smaller than that of calcite. Therefore, by combining the two and considering the differences and commonalities of thermal history of different strata, the regional thermal history can be accurately defined. Some areas may have only one type of carbonate stratum distribution, and it is difficult to obtain calcite and dolomite at the same time. In this case, the combination of samples from strata of different ages will become important. The method of layer-by-layer backstripping, that is, the lower stratum has one more section of thermal history than the upper stratum, can also accurately define the regional thermal history.

[0045] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention utilizes the cluster isotope method of carbonates in source rock interlayers or adjacent layers to restore the maturity (maximum paleotemperature experienced) of marine / lacustrine source rocks and regional paleothermal history technology, thereby providing a basis for realizing oil and gas resource evaluation and prediction of accumulation patterns, which is of great help to shale oil and gas and deep / ultra-deep oil and gas exploration. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a schematic diagram of the solid-state rearrangement evolution curves of calcite and dolomite at different heating rates provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0050] Example 1

[0051] This embodiment provides a method for restoring the regional thermal history of a marine sedimentary area, the method comprising the following steps:

[0052] (1) A large set of Ordovician micrite carbonate samples from the Tarim Basin were selected and the validity of the carbonate samples was analyzed to obtain the research samples;

[0053] (1.1) Selection and principles of carbonate samples

[0054] The selection of appropriate carbonate samples mainly considers the macroscopic vertical and horizontal distribution characteristics of the target area. For the maximum paleo-geothermal temperature, carbonate interlayer samples in mudstone can be selected; regional thermal history research is mainly based on the original thick sedimentary large set of carbonate layer samples, and multiple sets of carbonate strata are sampled vertically in multiple layers. If calcite and dolomite are distributed in the target area at the same time, the two carbonate minerals can be sampled at the same time; multiple mineral types and multiple layers of strata are jointly defined, so the regional thermal history can be accurately restored;

[0055] (1.2) Sample validity analysis

[0056] The two purposes of maximum paleo-geothermal and regional thermal history have completely different requirements for samples. The samples selected for maximum paleo-geothermal must be guaranteed to have been strongly affected during the maximum paleo-geothermal period, that is, evidence of the development and activity of diagenetic fluids such as strong multi-stage dissolution and cementation can be seen in carbonate minerals. Dissolution pores can be seen in carbonate interlayers, and precipitated cemented authigenic minerals can be seen everywhere. On the contrary, samples used for regional thermal history restoration should avoid being strongly affected by fluids as much as possible, and should be mainly mud crystal or powder crystal carbonate minerals.

[0057] The samples were subjected to thin section identification, cathode luminescence experiment and XRD tests. For the former, samples of micrite microcrystalline limestone and dolomite with strong dissolution, multiple stages of authigenic mineral filling, and calcite or dolomite purity exceeding 85% were selected. For the latter, samples of micrite microcrystalline limestone and dolomite with weak cathode luminescence, weak dissolution, and calcite or dolomite purity exceeding 95% were selected, avoiding cracks and filling zones;

[0058] (2) Pre-processing the source rock maturity test samples and paleo-thermal history research samples obtained in step (1), and then performing carbonate cluster isotope composition analysis and data validity selection to obtain test data;

[0059] (2.1) Sample pretreatment

[0060] The mudstone interlayer samples used for the maximum paleo-geothermal study will cause extremely inaccurate carbonate cluster isotope measurements, and may even cause the analysis and testing system to crash or paralyze, because mudstone often contains a lot of organic matter. Removing organic matter without destroying the isotope structure of carbonate clusters is the key to obtaining reliable data. Use a micro-drill to obtain core samples to artificially avoid interference from organic matter including kerogen and asphalt. After the sample is ground, flotation and other methods are used to physically separate the organic components. Then, 3% hydrogen peroxide is used to remove residual organic matter, followed by washing with distilled water 3 to 5 times and drying in a 40°C oven for 12 hours. Test and analyze the organic carbon content, preferably below the detection line;

[0061] For large sets of carbonate samples used for thermal history research, the organic matter content is generally lacking, except for the possible presence of asphalt. Avoid cracks and filling zones, avoid asphalt, use micro-drills to drill samples, grind them, and then conduct analytical testing;

[0062] (2.2) Carbonate cluster isotope composition analysis

[0063] The Δ of carbonate (dolomite or calcite) is measured using instruments such as Mat-253. 47 Value (while obtaining carbonate δ 13 C and δ 18 O). This step includes the conversion of carbonate into CO2, CO2 purification and testing, etc. These processes are relatively mature and will not be described here. It should be noted that the test analysis must be guaranteed to be more than 7 to 10 times, and each sample must be analyzed and tested 2 to 3 times for data validity analysis;

[0064] (2.3) Data validity selection

[0065] For the test data, standard deviation analysis is performed to screen truly effective and representative samples and data for the next step of work. This involves not only the analysis of experimental effectiveness but also the comprehensive analysis of sample effectiveness;

[0066] For a single sample, the results of 7 to 10 times obtained from a single measurement are mainly analyzed. The screening principle is based on d 13 C and D 18 The mean square error of O analysis is within 0.007 and does not exceed the required upper limit of 0.01; Δ 47 The maximum mean square error is 0.048, which does not exceed 0.05, and the data are all valid; then the results are compared three times, and the average absolute error is about 5%, which does not exceed 10%, which is valid;

[0067] (3) restoring paleotemperature and / or regional thermal history based on available data obtained in step (2);

[0068] (3.1) Restoration of ancient temperature

[0069] The measured surface temperature of carbonate cluster isotopes in the shale interlayer is between 175 and 180 degrees, reflecting the maximum burial paleotemperature of the stratum.

[0070] (3.2) Restoration of regional thermal history

[0071] The restoration of regional thermal history is mainly based on the calculation of the solid-state rearrangement structure reorganization kinetics of carbonate cluster isotopes, taking advantage of the different crystallization kinetics of calcite and dolomite: that is, although they have experienced the same thermal history, they show different evolution trends. Dolomite has a strong temperature lock effect. As the burial depth and temperature increase, the solid-state rearrangement amplitude is smaller than that of calcite (e.g. Figure 1 Therefore, by combining the two and considering both the differences and commonalities of thermal history in different layers, the regional thermal history can be precisely defined.

[0072] In some areas, there may be only one type of carbonate stratum distributed, and it is difficult to obtain calcite and dolomite at the same time. In this case, the combination of samples from strata of different ages will become important; adopting the layer-by-layer stripping method, that is, the lower stratum adds one more section of thermal history than the upper stratum, can also accurately define the regional thermal history.

[0073] The applicant declares that the present invention illustrates the detailed structural features of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present invention must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0074] The applicant declares that the present invention illustrates the detailed process flow of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed process flow, that is, it does not mean that the present invention must rely on the above-mentioned detailed process flow to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for restoring the maximum paleo-geothermal temperature and regional thermal history of a marine or lacustrine sedimentary area, characterized in that: The method comprises the following steps: (1) Select carbonate samples and conduct validity analysis on the carbonate samples to obtain maximum paleo-geothermal research samples and / or paleo-thermal history research samples; (2) Pre-processing the maximum paleo-geothermal research samples and / or paleo-thermal history research samples obtained in step (1), and then performing carbonate cluster isotope composition analysis and data validity selection to obtain test data; (3) Restore the maximum paleotemperature and / or regional thermal history based on the available data obtained in step (2).

2. The method according to claim 1, characterized in that The selection in step (1) includes: selecting the maximum paleo-geothermal sample and the regional thermal history sample in the target area strata; Preferably, the target area includes an area where calcite and dolomite are distributed simultaneously; Preferably, the maximum paleo-geothermal sample comprises a carbonate interlayer sample in mudstone; Preferably, the regional thermal history samples include large sets of original sedimentary thick layer carbonate layer samples.

3. The method according to claim 1 or 2, characterized in that: The maximum paleo-geothermal research samples in step (1) include micrite-microcrystalline limestone and dolomite samples with strong dissolution of mudstone interlayers and at least two stages of authigenic mineral filling; Preferably, the purity of the maximum paleo-geothermal research sample exceeds 95%; Preferably, the purity of the paleothermal history research sample exceeds 85%; Preferably, the paleothermal history research samples include micrite microcrystalline limestone and dolomite samples with weak cathode luminescence and weak dissolution; Preferably, the maximum paleo-geothermal research samples include carbonate rock samples with strong dissolution.

4. The method according to any one of claims 1 to 3, characterized in that: The sample pretreatment in step (2) includes sample pretreatment for maximum paleo-geothermal research and sample pretreatment for paleo-thermal history research; Preferably, the maximum paleo-geothermal research sample pre-treatment comprises: drilling with a dental drill, grinding, washing with hydrogen peroxide, washing with water and drying the maximum paleo-geothermal research sample in sequence; Preferably, the grinding is used to separate organic matter components; Preferably, the concentration of the hydrogen peroxide is 3 to 5 wt%; Preferably, the water washing is performed 3 to 5 times; Preferably, the drying temperature is 30-50°C; Preferably, the drying time is 10 to 15 hours.

5. The method according to claim 4, characterized in that The paleo-thermal history research sample pre-treatment comprises: grinding the paleo-thermal history research sample; Preferably, the particle size of the sample after the grinding process is less than 80 mesh.

6. The method according to any one of claims 1 to 5, characterized in that: The carbonate cluster isotope composition analysis in step (2) includes: using an instrument to independently measure Δ 47 value, and the carbonate δ 13 C and δ 18 O.

7. The method according to any one of claims 1 to 6, characterized in that: The data validity selection in step (2) includes: performing standard deviation analysis on the test data; Preferably, the standard deviation analysis includes single sample analysis and comprehensive comparative analysis of series of samples.

8. The method according to claim 7, characterized in that The single sample analysis includes: analyzing the results of 7 to 10 times obtained from a single measurement, and the screening principle is based on δ 13 C and δ 18 O analysis mean square error does not exceed 0.01, Δ 47 The mean square error is no more than 0.05, which is considered valid. Then the results are compared three times, and the average absolute error does not exceed 10%.

9. The method according to any one of claims 1 to 8, characterized in that: The method for recovering the maximum paleo-geothermal condition in step (3) includes: measuring the surface temperature corresponding to the carbonate cluster isotopes to reflect the maximum paleo-geothermal condition.

10. The method according to any one of claims 1 to 8, characterized in that: Step (3) The methods for recovering the thermal history of the domain include: calculation of the structural reorganization kinetics based on the solid-state rearrangement of carbonate cluster isotopes, Calcite and dolomite have different crystallization kinetics.

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