A method for quantitatively detecting adamantane compounds in rock

Abstract

The present application relates to the technical field of oil and gas exploration, and particularly relates to a method for quantitatively detecting adamantane compounds in rock. The method comprises the following steps: crushing a rock sample at low temperature, taking the crushed rock sample into a container, adding diatomite, a standard sample solution and an extractant, and sealing the container; performing ultrasonic extraction and low-temperature standing; centrifugally collecting supernatant, and placing the supernatant in a fume hood for volatilization; when 1-2 mL of supernatant remains, adding alumina for adsorption; before the solvent is completely volatilized, taking out the adsorbed alumina, and performing solid-phase extraction; concentrating the eluent after solid-phase extraction, and performing gas chromatography-mass spectrometry analysis on the concentrated solution. The method can quantitatively detect adamantane compounds in rock, has high accuracy, and simple operation steps.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas exploration, and particularly relates to a method for quantitatively detecting adamantane compounds in rocks. BACKGROUND

[0002] Adamantane compounds are a kind of rigid polymeric cyclic hydrocarbon compounds with diamond-like structure, which are commonly found in crude oil and rocks. Due to the unique molecular structure of adamantane, its properties are extremely stable, and it has strong resistance to thermal degradation and biodegradation. In the field of oil and gas exploration, it is widely used in maturity evaluation of high maturity crude oil and source rock.

[0003] Adamantane compounds are usually present in trace amounts in rocks, and even in high evolution degree source rock, the content is only several nanograms to several micrograms per gram. Adamantane compounds have a polarity between naphthenes and monocyclic aromatics, and are easily soluble in organic reagents. The extraction of adamantane compounds from rocks generally adopts Soxhlet extraction or rapid extraction method, which generates steam by heating organic solvent and condenses back flow to leach the crushed rock samples, so as to extract the organic matter in the rock step by step. Then, the saturated hydrocarbon part is obtained by column chromatography component separation, and finally the adamantane compounds are detected by chromatography-mass spectrometry. The whole operation process is too complicated, time-consuming, and requires a large amount of organic solvent. Moreover, adamantane compounds are easily weathered (sublimed), and the whole extraction process will cause a large amount of loss, which cannot be completely preserved or completely lost, making subsequent quantitative detection difficult.

[0004] Chinese patent application CN102768256A discloses a method for quantitatively detecting adamantane compounds in petroleum samples by using comprehensive two-dimensional gas chromatography. The method comprises the following steps: (1) preparing a sample to be tested; (2) analyzing the sample to be tested by using comprehensive two-dimensional gas chromatography-time of flight mass spectrometry to obtain peak information of adamantane compounds in the sample to be tested; (3) analyzing the sample to be tested by using comprehensive two-dimensional gas chromatography-hydrogen flame ionization detector to obtain a comprehensive two-dimensional gas chromatography-hydrogen flame ionization detection spectrum of the sample to be tested; (4) determining the peak positions of adamantane compounds and D16-adamantane on the comprehensive two-dimensional gas chromatography-hydrogen flame ionization detection spectrum according to the peak information of adamantane compounds obtained in step (2), and obtaining the peak area integral results thereof; (5) calculating and obtaining the quantitative results of adamantane compounds by using internal standard method. The method is suitable for the quantitative detection of adamantane compounds in all crude oil and rock extract samples.

[0005] The method comprises the following steps of preparing a sample to be tested: when the sample to be tested is a condensate oil sample, taking an appropriate amount of the condensate oil sample into a 1.5 mL automatic injection bottle, and adding 300 μL of a prepared D16-adamantane standard sample to obtain the sample to be tested; and when the sample to be tested is other crude oil or rock extract sample, 1.8 g of fine silica gel is loaded into a glass column under shaking, 30 mg of the other crude oil or rock extract sample is taken, dissolved with an appropriate amount of n-hexane, 300 μL of the prepared D16-adamantane standard sample is added, and then all of the sample is transferred into the glass column, eluted with 3 mL of n-hexane, and eluted fractions are collected and concentrated into a 1.5 mL automatic injection bottle to obtain the sample to be tested.

[0006] Currently, there are few reports on methods for directly measuring adamantane compounds in rocks. Therefore, a method with simple steps and accurate detection of adamantane compounds in rocks is still needed. Summary of the Invention

[0007] The main purpose of the present invention is to provide a method for quantitatively detecting adamantane compounds in rocks. The method of the present invention can accurately detect adamantane compounds in rocks, has simple steps, and reduces sample loss throughout the process.

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

[0009] The present invention provides a method for quantitatively detecting adamantane compounds in rocks. The method comprises the following steps: crushing a rock sample at low temperature, placing the crushed rock sample in a container, adding diatomaceous earth, a standard sample solution and an extractant, and sealing the container; performing ultrasonic extraction and standing at low temperature; collecting a supernatant by centrifugation, placing the supernatant in a fume hood for volatilization, and adding aluminum oxide for adsorption when 1-2 mL of the supernatant remains; taking out the adsorbed aluminum oxide before the solvent is completely evaporated, and performing solid-phase extraction; concentrating the eluate after the solid-phase extraction, and performing gas chromatography-mass spectrometry analysis on the concentrated solution.

[0010] Furthermore, in the container, the mass ratio of the crushed rock sample to diatomaceous earth is 1-10:1, the mass volume ratio of the crushed rock sample to the standard sample solution is 0.1-1 g / μL; and the mass volume ratio of the crushed rock sample to the extractant is 0.1-1.5 g / mL.

[0011] Furthermore, the extractant is one of dichloromethane, chloroform and benzene.

[0012] Furthermore, in the container, the mass ratio of the crushed rock sample to diatomaceous earth is 1-5:1, the mass volume ratio of the crushed rock sample to the standard sample solution is 0.1-0.5 g / μL; the mass volume ratio of the crushed rock sample to the extractant is 0.1-0.5 g / mL.

[0013] Furthermore, in the standard sample solution, the standard sample is adamantane-D16, and the solvent is a low-polarity solvent, including but not limited to isooctane; the concentration of the standard sample solution is 1 μg / mL to 50 μg / mL.

[0014] Furthermore, the ultrasonic extraction and low-temperature standing steps are repeated several times.

[0015] Furthermore, the ultrasonic extraction conditions are: temperature ≤ 30°C, ultrasonic power 240-360W, frequency 40-45KHz; ultrasonic extraction 15-45min; standing at 0-10°C for 45min or more.

[0016] Further, centrifugation is performed at 2000-5000 rpm for 10-20 minutes, and the centrifugation temperature is ≤30°C;

[0017] Furthermore, the adsorbed alumina was placed in an alumina / ZSM-5 molecular sieve solid phase extraction column and eluted with isooctane, with the eluent flow rate controlled at 20-30 drops / min.

[0018] Furthermore, the gas chromatography-mass spectrometry analysis conditions are:

[0019] Capillary column: DB5-MS, 60m*0.25mm*0.25μm.

[0020] Carrier gas: high-purity helium, flow rate 1.0 mL / min;

[0021] Heating program: maintain at 60 °C for 2 min, increase to 300 °C at a rate of 4 °C / min, and maintain for 30 min;

[0022] Injection mode: splitless;

[0023] Acquisition mode: Selected ion scan.

[0024] Furthermore, the particle size of the rock sample after crushing is ≤60 mesh; the added alumina is neutral alumina, and its particle size is 100-200 mesh.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] The method of the present invention is used to quantitatively detect adamantane compounds in rocks, with a short analysis process, simple operation steps, small amount of solvent used, high recovery rate and more accurate quantification. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the mass chromatogram of single adamantane compounds in the rocks of Well YX-94;

[0028] Figure 2 This is the mass chromatogram of diadamantanes in the rocks of Well YX-94. DETAILED DESCRIPTION

[0029] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0030] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations and / or combinations thereof.

[0031] In order to enable those skilled in the art to more clearly understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0032] Example 1

[0033] A method for quantitatively detecting adamantane compounds in rocks comprises the following steps:

[0034] Step 1. Standard sample preparation:

[0035] Deuterated adamantane, i.e., adamantane-D16, was used as the internal standard for quantitative detection of adamantane compounds, with isooctane as the solvent and a preparation concentration of 50 μg / mL.

[0036] Step 2. Sample preparation:

[0037] Select a certain amount of rock sample and crush it to 60 mesh or less in a copper mortar cooled with liquid nitrogen. Weigh 5 g of the crushed sample and place it into a screw-top sample bottle. Add 0.5 g of diatomaceous earth, 20 μL of the deuterated adamantane isooctane solution prepared in Step 1, and 20 mL of dichloromethane. Tighten the cap and seal.

[0038] Step 3. Organic matter extraction:

[0039] Place the prepared sample bottle in an ultrasonic cleaner with an ultrasonic power of 240W and a frequency of 40KKHz for 15 minutes. During the ultrasonic extraction process, the temperature is controlled below 30°C. Take it out and let it stand at 4°C for 45 minutes or more. Repeat this step several times to dissolve the organic matter in the rock as completely as possible.

[0040] After the ultrasonic vibration is completed, the sample bottle is placed in a centrifuge and centrifuged at 5000r / min for 10 minutes to separate the solid and liquid and maximize the extraction liquid;

[0041] The extract was filtered into a weighing bottle and the solvent was evaporated in a fume hood. When the extract remained to about 1.5 mL, 2 g of neutral alumina with a particle size of 200 mesh was added. The alumina fully adsorbed the organic matter in the extract to be tested. Be careful not to let the solvent evaporate and dry out completely.

[0042] Step 4. Adamantane enrichment:

[0043] Transfer the sample-adsorbed alumina to an alumina / ZSM-5 molecular sieve solid-phase extraction column mounted on a vacuum extraction apparatus. Place a weighing bottle inside to collect the extract. Use isooctane as the eluent. Control the pressure to maintain a flow rate of approximately 25 drops / minute. Alumina adsorbs asphaltenes, colloids, and aromatic hydrocarbons, while ZSM-5 molecular sieve adsorbs straight-chain alkanes, eluting only normal alkanes (including adamantane compounds). Concentrate the eluate to approximately 2 mL and transfer it to a 2 mL sample vial for analysis.

[0044] Step 5. Gas chromatography / mass spectrometry analysis:

[0045] After the instrument is stable, set the gas chromatography and mass spectrometry conditions.

[0046] Capillary column: DB5-MS, 60m*0.25mm*0.25μm.

[0047] Carrier gas: high-purity helium, flow rate 1.0 mL / min;

[0048] Heating program: maintain at 60 °C for 2 min, increase to 300 °C at a rate of 4 °C / min, and maintain for 30 min;

[0049] Injection mode: splitless;

[0050] Acquisition mode: selected ion scan (SIM);

[0051] The sample obtained in step 4 is injected into the chromatograph, the instrument is started for testing, the computer collects data, and the content of the adamantane compound in the rock is obtained through data processing.

[0052] Example 2

[0053] A method for quantitatively detecting adamantane compounds in rocks comprises the following steps:

[0054] Step 1. Standard sample preparation:

[0055] Deuterated adamantane, i.e., adamantane-D16, was used as the internal standard for the quantitative detection of adamantane compounds, with isooctane as the solvent and a preparation concentration of 10 μg / mL.

[0056] Step 2. Sample preparation:

[0057] Select a certain amount of rock sample and crush it to 60 mesh or less in a copper mortar cooled with liquid nitrogen. Weigh 5.4 g of the crushed sample and place it into a screw-top sample bottle. Add 1.8 g of diatomaceous earth, 20 μL of the deuterated adamantane isooctane solution prepared in Step 1, and 20 mL of dichloromethane. Tighten the cap and seal.

[0058] Step 3. Organic matter extraction:

[0059] The prepared sample bottles were placed in an ultrasonic cleaner with an ultrasonic power of 360W and a frequency of 40KHz for 20 minutes. The temperature was controlled below 30°C during the ultrasonic extraction process. The sample bottles were taken out and allowed to stand at 4°C for 1 hour. This step was repeated several times to allow the organic matter in the rock to be dissolved as completely as possible.

[0060] After the ultrasonic vibration is completed, the sample bottle is placed in a centrifuge and centrifuged at 4000r / min for 15min to separate the solid and liquid and maximize the extraction liquid;

[0061] The extract was filtered into a weighing bottle and the solvent was evaporated in a fume hood. 1 g of neutral alumina (100 mesh particle size) was added to the remaining 1 mL of the extract. The alumina fully adsorbed the organic matter in the extract to be tested. Be careful not to let the solvent evaporate completely.

[0062] Step 4. Adamantane enrichment:

[0063] Transfer the sample-adsorbed alumina to an alumina / ZSM-5 molecular sieve solid-phase extraction column, mounted on a vacuum extraction apparatus. Place a weighing bottle inside to collect the extract. Use isooctane as the eluent. Control the pressure to maintain a flow rate of 20 drops / min. Alumina adsorbs asphaltenes, colloids, and aromatic hydrocarbons, while ZSM-5 molecular sieve adsorbs straight-chain alkanes, eluting only normal alkanes (including adamantane compounds). Concentrate the eluate to approximately 2 mL and transfer it to a 2 mL sample vial for analysis.

[0064] Step 5. Gas chromatography / mass spectrometry analysis:

[0065] After the instrument is stable, set the gas chromatography and mass spectrometry conditions.

[0066] Capillary column: DB5-MS, 60m*0.25mm*0.25μm.

[0067] Carrier gas: high-purity helium, flow rate 1.0 mL / min;

[0068] Heating program: maintain at 60 °C for 2 min, increase to 300 °C at a rate of 4 °C / min, and maintain for 30 min;

[0069] Injection mode: splitless;

[0070] Acquisition mode: selected ion scan (SIM);

[0071] The sample obtained in step 4 is injected into the chromatograph, the instrument is started for testing, the computer collects data, and the content of the adamantane compound in the rock is obtained through data processing.

[0072] The rock samples from Well YX-94 in the Shengli Oilfield of Shandong Province were used as an example for quantitative analysis using the method described in this example. Ions m / z 136, 135, 152, 149, 163, 177, 191, 188, 187, 201, 215, 240, and 239 were collected. The content of adamantane compounds in the rock samples from Well YX-94 was obtained by data processing, as shown in Table 1. The mass chromatogram is shown in Table 1. Figure 1 and Figure 2 .

[0073] Table 1. Quantitative results of adamantane compounds in rocks from Well YX-94

[0074]

[0075] Example 3

[0076] A method for quantitatively detecting adamantane compounds in rocks comprises the following steps:

[0077] Step 1. Standard sample preparation:

[0078] Deuterated adamantane, i.e., adamantane-D16, was used as the internal standard for the quantitative detection of adamantane compounds, with isooctane as the solvent and a preparation concentration of 1 μg / mL.

[0079] Step 2. Sample preparation:

[0080] Select a certain amount of rock sample and crush it to 60 mesh or smaller in a copper mortar cooled with liquid nitrogen. Weigh 10 g of the crushed sample into a screw-top sample bottle and add 2 g of diatomaceous earth. Also add 20 μL of the deuterated adamantane isooctane solution prepared in Step 1 and 20 mL of dichloromethane. Tighten the cap and seal.

[0081] Step 3. Organic matter extraction:

[0082] Place the prepared sample bottle in an ultrasonic cleaner with an ultrasonic power of 300W and a frequency of 45KHz for 45 minutes. During the ultrasonic extraction process, the temperature is controlled below 30°C. Take it out and let it stand at 5°C for 45 minutes. Repeat this step several times to dissolve the organic matter in the rock as completely as possible.

[0083] After the ultrasonic vibration is completed, the sample bottle is placed in a centrifuge and centrifuged at 2000r / min for 20min to separate the solid and liquid and maximize the extraction liquid;

[0084] The extract was filtered into a weighing bottle and the solvent was evaporated in a fume hood. When the extract was about 2 mL, 1 g of neutral alumina with a particle size of 200 mesh was added. The alumina fully adsorbed the organic matter in the extract to be tested. Be careful not to let the solvent evaporate completely;

[0085] Step 4. Adamantane enrichment:

[0086] Transfer the sample-adsorbed alumina to an alumina / ZSM-5 molecular sieve solid-phase extraction column mounted on a vacuum extraction apparatus. Place a weighing bottle inside to collect the extract. Use isooctane as the eluent. Control the pressure to maintain a flow rate of 30 drops / minute. Alumina adsorbs asphaltenes, colloids, and aromatic hydrocarbons, while ZSM-5 molecular sieve adsorbs linear alkanes, eluting only normal alkanes (including adamantane compounds). Concentrate the eluate to approximately 2 mL and transfer it to a 2 mL sample vial for analysis.

[0087] Step 5. Gas chromatography / mass spectrometry analysis:

[0088] After the instrument is stable, set the gas chromatography and mass spectrometry conditions.

[0089] Capillary column: DB5-MS, 60m*0.25mm*0.25μm.

[0090] Carrier gas: high-purity helium, flow rate 1.0 mL / min;

[0091] Heating program: maintain at 60 °C for 2 min, increase to 300 °C at a rate of 4 °C / min, and maintain for 30 min;

[0092] Injection mode: splitless;

[0093] Acquisition mode: selected ion scan (SIM);

[0094] The sample obtained in step 4 is injected into the chromatograph, the instrument is started for testing, the computer collects data, and the content of the adamantane compound in the rock is obtained through data processing.

[0095] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for quantitatively detecting adamantane compounds in rocks, characterized in that: The rock sample is crushed at low temperature, placed in a container, diatomaceous earth, a standard sample solution, and an extractant are added, and the container is sealed; ultrasonic extraction is performed and the sample is allowed to stand at low temperature; the supernatant is collected by centrifugation and placed in a fume hood for evaporation; when 1-2 mL of the supernatant remains, aluminum oxide is added for adsorption; before the solvent is completely evaporated, the adsorbed aluminum oxide is removed and solid-phase extraction is performed; the eluate after solid-phase extraction is concentrated, and the concentrated solution is analyzed by gas chromatography-mass spectrometry; The adsorbed alumina was placed in an alumina / ZSM-5 molecular sieve solid phase extraction column and eluted with isooctane.

2. The method according to claim 1, characterized in that In the container, the mass ratio of the crushed rock sample to diatomaceous earth is 1-10:1, the mass volume ratio of the crushed rock sample to the standard sample solution is 0.1-1 g / μL; and the mass volume ratio of the crushed rock sample to the extractant is 0.1-1.5 g / mL.

3. The method according to claim 2, characterized in that In the container, the mass ratio of the crushed rock sample to diatomaceous earth is 1-5:1, the mass volume ratio of the crushed rock sample to the standard sample solution is 0.1-0.5 g / μL; the mass volume ratio of the crushed rock sample to the extractant is 0.1-0.5 g / mL.

4. The method according to any one of claims 1 to 3, characterized in that In the standard sample solution, the standard sample is adamantane-D16, the solvent is isooctane; and the concentration of the standard sample solution is 1 μg / mL to 50 μg / mL.

5. The method according to claim 1, wherein The ultrasonic extraction and low-temperature standing steps were repeated several times.

6. The method according to claim 1 or 5, characterized in that Ultrasonic extraction conditions: Ultrasonic extraction for 15-45 min; standing at 0-10°C for 45 min or more.

7. The method according to claim 1, characterized in that Centrifuge at 2000-5000 rpm for 10-20 minutes.

8. The method according to claim 1, characterized in that The flow rate of the isooctane elution solution is controlled at 20-30 drops / min.

9. The method according to claim 1, characterized in that Gas chromatography-mass spectrometry analysis conditions were: Capillary column: DB5-MS, 60m*0.25mm*0.25µm; Carrier gas: high-purity helium, flow rate 1.0 mL / min; Heating program: maintain at 60 °C for 2 min, increase to 300 °C at a rate of 4 °C / min, and maintain for 30 min; Injection mode: splitless; Acquisition mode: Selected ion scan.

10. The method according to claim 1, characterized in that The particle size of the rock sample after crushing is ≥60 mesh; the added alumina is neutral alumina with a particle size of 100-200 mesh.

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