RU2739138C1 - Analytical complex and method of operation thereof for analysis of total and individual content of hydrocarbons in samples of oil-bearing rocks by pyrolysis chromatography - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: present invention relates to analysis of materials, in particular to method and complex of analysis of total and individual content of hydrocarbons in samples of oil-bearing rocks. Analytical system for analysis of total and individual content of hydrocarbons (HC) in samples of oil-bearing rocks consists of: gas chromatograph (GC) containing: first thermostat formed by inner GC volume; evaporator with installed pyrolytic cell, providing thermal desorption and/or pyrolysis of oil-bearing rock sample; cryogenic trap providing collection of thermal desorption and pyrolysis products at sample heating stage; a chromatographic column which provides HC separation and connected to the cryogenic trap; a second thermostat to program temperature of the chromatographic column; Dean switch, connected to GC evaporator and chromatographic column, providing redirection of flow with thermodesorption products or sample pyrolysis into channel with chromatographic column or directly into MSD; a flow divider combining the streams with the sample from different channels into one channel for transmission to the MSD; MSD connected to the GC and providing HC detection in the sample; a source of feeding liquid nitrogen, connected to a cryogenic trap, which provides cryofocusing of thermal desorption and pyrolysis products in the initial section of the column for their complete subsequent separation; a computing control device connected to the GC; wherein the sample is analyzed in switchable modes of operation of the complex, in which analysis is carried out with programmable pyrolysis temperature (EGA-MS) to record the total weight of free hydrocarbons (S1) and the HC pyrolysis (S2) and calculation of temperature of cracking of organic substance Tmax, as well as pyrolysis gas chromatography (PY-GC/MS) for individual analysis of HC types in each temperature zone of thermal desorption and pyrolysis.

EFFECT: technical result is broader functional capabilities for analysis of hydrocarbons in samples of oil-bearing rocks.

9 cl, 6 dwg

Description

FIELD OF TECHNOLOGY

The present invention relates to the field of analysis of materials for the study of their properties, in particular to a method and a complex embodying it for the analysis of the total and individual content of hydrocarbons in samples of oil-bearing rocks by pyrolytic chromatography.

LEVEL OF TECHNOLOGY

Today there is an international standard for measuring the content of hydrocarbons (HC) in samples of oil-bearing rocks, which is used by geochemists to assess the oil-bearing potential of rocks. For the physical implementation of this approach, devices are used, in particular, analyzers manufactured by such companies as: Vinci Techologies (Rock Eval 7 analyzer, https://www.vinci-technologies.com/products-explo.aspx?IDR=82289&idr2=82568&idp = 82288 & IDM = 536784), Wildcat Technologies ( https://www.wildcattechnologies.com/products/hawk-1 ) and Weatcherford ( https://www.weatherford.com/getattachment/bdede71f-a2da-4276-b9c5-dbe5009d2f5a/ Source-Rock-Analyzer.pdf ) .

The general methodology was developed in the late 70s by the French Petroleum Institute. The first commercial device was proposed by Vinci Tehcnologies back in 1998 and until 2008 they had a patent for this technology. Therefore, there were no commercial analogues for this device. After 2008, other players appeared on the market, they began to produce replicas of these devices. The aforementioned manufacturers use a technology in which the detector is located above the pyrolysis furnace to register the emitted hydrocarbons. Also, classical devices use a detection method - a flame ionization detector (FID) and an IR detector, which do not allow obtaining a complete picture of the required parameters of the HC content in the samples.

Known hardware makes it possible to determine metrics such as S1, S2, and Tmax. This known method is programmable pyrolysis temperature analysis (EGA-MS). Another well-known method for analyzing individual HC parameters in a sample is pyrolytic gas chromatography (PY-GC / MS), which is used for the individual analysis of HC types in each of the temperature zones of thermal desorption and pyrolysis.

The main disadvantage of the known solutions is that there are currently no means allowing to work simultaneously in the above two modes, which critically reduces the functionality and complicates the analysis process due to the need to use various devices to achieve the desired effect.

DISCLOSURE OF THE INVENTION

The claimed invention solves the technical problem of creating a multifunctional analytical complex that provides the ability to perform HC analysis in oil-bearing rock samples in the EGA-MS and PY-GC / MS modes.

The technical result is to expand the functionality for the analysis of hydrocarbons in samples of oil-bearing rocks, due to the provision of the analytical complex in two modes: EGA-MS and PY-GC / MS.

The stated result is achieved due to the analytical complex for the analysis of the total and individual content of hydrocarbons (HC) in the samples of oil-bearing rocks, consisting of:

- gas chromatograph (GC) containing:

- the first thermostat formed by the internal volume of the GC;

- an evaporator with an installed pyrolytic cell providing thermal desorption and / or pyrolysis of a sample of oil-bearing rock;

- a cryogenic trap that captures the products of thermal desorption and pyrolysis at the stage of heating the sample;

- chromatographic column providing individual separation of hydrocarbons and connected to a cryogenic trap;

- the second thermostat providing programming of the temperature of the chromatographic column;

- Dean's switch connected to the GC evaporator and the chromatographic column, which redirects the flow with the products of thermal desorption or pyrolysis of the sample to the channel with the chromatographic column or directly to the MSD;

- a flow divider, providing a combination of flows with a sample from different channels into one channel for transmission to the MSD;

- MSD connected to the GC and providing HC detection in the sample;

- a liquid nitrogen supply source connected to a cryogenic trap, which provides cryofocusing of thermal desorption and pyrolysis products in the initial section of the column for their complete subsequent separation;

- computing control device connected to the GC;

moreover

the study of the sample is carried out in switchable operating modes of the complex, in which analysis is carried out with a programmable pyrolysis temperature (EGA-MS) to register the indicators of the total mass fraction of free hydrocarbons (S1) and pyrolysis HCs (S2) and calculate the cracking temperature of organic matter Tmax, as well as gas chromatography (PY-GC / MS) for individual analysis of HC types in each of the temperature zones of thermal desorption and pyrolysis.

In one of the particular embodiments of the complex, the evaporator, Dean switch and divider are located in the first GC thermostat and are connected by quartz capillaries.

Another particular embodiment of the complex contains a crane that controls the Dean switch.

In another particular embodiment of the complex, the additional thermostat is a low thermal inertia module (LTM).

In another particular embodiment of the complex, the LTM is located externally, on the door of the first GC oven.

In another particular embodiment of the complex, the liquid nitrogen supply source is a Dewar vessel.

In another particular embodiment of the complex, the computing control device is a personal computer, laptop, tablet or smartphone.

In another particular embodiment of the complex, the computer control device registers and processes chromatogram data in the Py-GCMS operating mode and pyrograms for the EGA-MS operating mode.

The claimed invention is also carried out using a method for analyzing the content of the mass fraction of free hydrocarbons and hydrocarbons of pyrolysis in oil-bearing rock samples using the above complex, in which the analysis is carried out in an automatic mode, selected from the EGA-MS mode with a given pyrolysis temperature range and examining the samples in the MSD, and the mode of pyrolytic gas chromatography PY-GC / MS for the analysis of HC types in each of the temperature zones of thermal desorption and pyrolysis.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a general view of the claimed complex.

FIG. 2A shows a diagram of the complex operation in the EGA-MS mode.

FIG. 2B shows a pyrogram of readings in the EGA-MS mode.

FIG. 3A shows a diagram of the complex operation in the PY-GC / MS mode.

FIG. 3B shows chromatograms of detailed analysis of fractions S1 and S2.

FIG. 3B is a fragment of the lower chromatogram in FIG. 3B.

CARRYING OUT THE INVENTION

FIG. 1 shows a diagram of the analytical complex (10). The complex (10) is built on the basis of a gas chromatography-mass spectrometer and a pyrolytic attachment for gas chromatography, and includes a pyrolytic cell (110), inside which is placed a crucible (111) with a rock sample installed in a gas chromatograph (GC) (120 ), which is connected to a mass detector (MSD) (130) and a control computer (140).

GC (120) is a device for analyzing complex gas mixtures of substances by differentiating them into monocomponents. Further, the components of the mixture are analyzed for qualitative and quantitative characteristics. In this case, research can be carried out using any physical and chemical methods. GC (120) operates according to the general principles of chromatography. This means that the elements of the mixture are distributed between two phases: mobile (eluent) and stationary. For GC (120), it is typical to conduct research where gas or vapor acts as a mobile phase. The most common eluents are helium, hydrogen and nitrogen. The stationary phase can be either a solid (then we are talking about gas absorption chromatography), and a liquid substance (in this case, it is customary to talk about gas-liquid chromatography).

The GC (120) contains the main internal volume that forms the first oven. Inside the thermostat are installed: evaporator (121), cryogenic trap (122), capillaries (1251-1254), divider (126) and Dean switch (127). A second thermostat (124) is installed on the door of the first thermostat, inside of which is a chromatographic column 123). MSD (130) provides HC detection in the sample.

An evaporator (121) serves as an interface for transferring pyrolysis products to the GC (120). A cryogenic trap (122) provides cryofocusing (trapping) of pyrolysis products in the Py-GCMS mode of the complex (10). The chromatographic column (123) implements the function of separating the mixture, while the column (123) is located in the second thermostat (124).

The second thermostat (124) is used to place the chromatographic column (123) and its non-heating / cooling, regardless of the temperature of the first thermostat (internal volume of the GC (120)). Capillaries (125 ₁ - 125 ₄ ) GC (120) serve as switching elements of all nodes to combine all elements of the complex (10) into one circuit for the passage of pyrolysis / thermal desorption products from the pyrolytic cell (110) into the MSD (130).

The pyrolytic cell (110) provides heating of a crushed rock sample, which was previously placed in a crucible (111) for subsequent HC analysis using an MSD (130). The cell (110) is fixed to the evaporator (121) and is connected to the carrier gas source (helium bottle (112)), through the regulator (128), installed on the GC (120) or in another place providing its functionality. Regulator (128) allows you to set the desired pressure and flow rate of helium from reservoir (112) for the passage of pyrolysis / thermal desorption products from cell (110) to MSD (130).

Capillaries (125 ₁ -125 ₄ ) used in GC (120) are made, in particular, of quartz glass or steel, which provides communication of all elements of the gas circuit for the possibility of automatic switching between the EGA-MS and Py-GCMS modes.

The complex (10) also contains vessels with helium (112) and liquid nitrogen (113) to ensure operation in the stated modes. In the EGA-MS mode, helium from a cylinder (112) is used, for the Py-GC / MS mode, helium (112) and liquid nitrogen (113). A Dewar vessel can be used as a container for storing liquid nitrogen (113).

FIG. 2A shows an example of the complex operation in the EGA-MS mode.

The sample in the pyrolytic cell (110) starts to heat up. All hydrocarbons released during the stage of thermal desorption (S1) (at temperatures from 100 to 300 ° С) and pyrolysis (S2) (at temperatures from 400 to 650 ° С) are quantitatively recorded on (or using) MSD (130) in the recording mode of the total ion current. The quantitative calculation is carried out from the area of the integrated peaks in the pyrogram using the MSD response coefficient (130), calculated after measuring the area of the peaks of similar products in the analysis of a standard sample. The resulting EGA pyrogram (Fig. 2B) is also used to calculate Tmax (the temperature of cracking of organic matter or the temperature at which the maximum intensity of formation of pyrolysis hydrocarbons is noted) and serves as the basis for further experiments with samples in other modes.

To determine the types of hydrocarbons in each of the temperature zones (thermal desorption zone and pyrolysis zone), the measuring complex (10) must be activated in the Py-GC / MS mode (Fig. 3A). Instead of an EGA capillary (125 ₂ ), a chromatographic column (123) is used (for example, a quartz tube 30 m long and 0.25 mm in diameter, on the inner wall of which a sorbent is chemically grafted - polydimethylsiloxane, which has a different sorption force to different classes of chemical compounds) to separate products thermal desorption and pyrolysis for individual hydrocarbons. In this case, the initial section of the column (123) passes through a cryogenic trap (122) to trap all products of thermal desorption and pyrolysis at the stage of heating the sample, prior to chromatographic separation.

The sample (also preliminarily crushed and weighed) undergoes a two-stage analysis. First, it is analyzed in the thermal desorption mode (the cell temperature (110) is set around 300 ° C) with the accumulation of all freely released products in a cryogenic trap (122) and their subsequent chromatographic separation (analysis of the S1 fraction), and then, without removing the sample, activation using a computer control device (140) for the pyrolysis stage (the cell temperature is set at 650 ° C), also with the accumulation and chromatography of all products of thermal cracking of organic substances (analysis of the S2 fraction).

This approach provides additional information about the sample that is not available on traditional systems. For example, detailed component analysis of peak S1 will provide information on the distribution of normal paraffins and isoprenoid compounds (see FIG. 3B). Analysis of the S2 fraction makes it possible, without preliminary extraction, to detect a number of biomarkers characterizing the sedimentation environment, lithological conditions, maturity and type of organic matter (OM) and the kinetics of its transformation. You can also estimate the amount of sulfur-containing substances and their structure.

FIG. 3B shows a chromatogram of a detailed analysis of the S1 fraction. The exit points of normal paraffins are indicated on the chromatograms with a number corresponding to the number of carbon atoms in the molecule. Pristane and phytane were confidently detected in the chromatogram of the S1 fraction after the release of n-C17 and n-C18, respectively, which is confirmed by signals from characteristic ions (m / z 55 and 57) detected on a mass-selective detector (130).

After a detailed analysis of the chromatogram of the S2 fraction (see Fig.3B) obtained in the full scan mode, experiments were carried out with the accumulation of a signal for individual specific ions (m / z 184, 198 and 212) characteristic of aromatic compounds such as dibenzothiophene and its homologues. By analyzing the SIM-chromatogram for ion 191.2, it is possible to extract information about tricyclic terpenes and, for example, the ratio of such important biomarkers as hopanes C27.

For automatic switching between the EGA-MS and Py-GC / MS modes, a scheme of the complex (10) is proposed, in which the GC evaporator (121) (120) is connected to the Dean switch (127) using a quartz capillary (125 ₁ ). The Dean switch (127) has two outputs, one of which is connected to the EGA capillary (125 ₂ ), and the other to the chromatographic column (123). Dean's switch (127) redirects the flow with the products of thermal desorption or pyrolysis of the sample either to the channel with the chromatographic column (123), or directly to the MSD (130) through the EGA capillary (125 ₂ ).

This direction can be controlled by a tap (129) to which a Dean switch (127) is connected. Depending on the position of the valve (129), the analysis products go directly to the MSD (130), which allows obtaining a pyrogram of the analysis of peaks S1 and S2. When the valve (129) is off, the analysis products enter the MSD (130), which produces the chromatogram shown in FIG. 2B, i.e. two peaks - S1 and S2.

If the valve (129) is turned on, then the hydrocarbons under the pressure of gas (helium) in the other direction into the column (123), and in it are divided by boiling points, which allows you to obtain the chromatogram shown in Fig. 3B.

The EGA capillary (125 ₂ ) and the chromatographic column (123) cannot be in the first GC oven (120) at the same time, because they must have different temperatures - for the capillary (125 ₂ ) a constant (usually 300 ° C), and for the column (123) program (for example, from 70 to 320 ^° C at a rate of 100 ° C / min). In order to remove this limitation, a second thermostat (124) is used, for example, LTM technology - a low thermal inertia module that can be placed on the outside of the GC housing (door) (120), i.e. the first thermostat.

The second limitation is the presence of two outputs (from the capillary (125 ₂ ) and from the column (123)) and one input, since one MSD (130) is used, which records the signal. Thus, it is necessary to combine the two mentioned channels into one. For this, the flow divider (126) (eng. 2-way splitter with make up) is used. The flow divider (126) can be two metal plates welded to each other, inside which microchannels are etched to form two inlets and one outlet, as well as the possibility of blowing a carrier gas through a regulator (128) (for example, helium) to create a pressure difference between channels.

As a result, in the software of the device (140), for example, a computer, laptop, tablet or smartphone, to control the complex (10), it is possible to select the required operating mode containing preset temperature parameters, the position of the tap (129) for the Dean switch (127), all pressure and gas flow rates are required. The device (140) automatically provides transfer and installation in the GC (120), the device will automatically set these parameters and the sample can be analyzed in one of the selected modes - either in EGA-MS or Py-GCMS.

The device (140) is connected to the GC (120) using a wired or wireless communication principle, for example, Ethernet, USB, RS232, WLAN, WAN, Bluetooth, Wi-Fi, etc. The operation modes of the complex (10) can be controlled both manually and remotely.

The claimed solution also allows to expand the arsenal of technical means and implement more functional complexes for the analysis of hydrocarbons in samples of oil-bearing rocks.

In the present application materials, the preferred disclosure of the implementation of the claimed technical solution was presented, which should not be used as limiting other, particular embodiments of its implementation, which do not go beyond the scope of the claimed scope of legal protection and are obvious to specialists in the relevant field of technology.

Claims (22)

1. Analytical complex for the analysis of the total and individual content of hydrocarbons (HC) in samples of oil-bearing rocks, consisting of: - gas chromatograph (GC) containing: the first thermostat formed by the internal volume of the GC; an evaporator with an installed pyrolytic cell providing thermal desorption and / or pyrolysis of the oil-bearing rock sample; a cryogenic trap that captures the products of thermal desorption and pyrolysis at the stage of heating the sample; chromatographic column, providing individual separation of hydrocarbons and connected to a cryogenic trap; a second thermostat for programming the temperature of the chromatographic column; Dean switch, connected to the GC evaporator and chromatographic column, which redirects the flow of thermal desorption or sample pyrolysis products to the channel with the chromatographic column or directly to the MSD; a flow divider that combines sample streams from different channels into one channel for transmission to the MSD; - MSD connected to GC and providing HC detection in the sample; - a liquid nitrogen supply source connected to a cryogenic trap, which provides cryofocusing of thermal desorption and pyrolysis products in the initial section of the column for their complete subsequent separation; - computing control device connected to the GC; moreover the study of the sample is carried out in switchable operating modes of the complex, in which analysis is carried out with a programmable pyrolysis temperature (EGA-MS) to register the indicators of the total mass fraction of free hydrocarbons (S1) and pyrolysis HCs (S2) and calculate the cracking temperature of organic matter Tmax, as well as gas chromatography (PY-GC / MS) for individual analysis of HC types in each of the temperature zones of thermal desorption and pyrolysis. 2. The complex according to claim 1, characterized in that the evaporator, Dean switch and divider are located in the first GC thermostat and are connected by quartz capillaries. 3. The complex according to claim 1, characterized in that it contains a crane that controls the Dean switch. 4. The complex of claim 1, wherein the additional thermostat is a low thermal inertia module (LTM). 5. The complex according to claim 1, characterized in that the LTM is located outside, on the door of the first GC oven. 6. The complex according to claim 1, characterized in that the liquid nitrogen supply source is a Dewar vessel. 7. The complex according to claim 1, characterized in that the computing control device is a personal computer, laptop, tablet or smartphone. 8. The complex according to claim 7, characterized in that the computing control device registers and processes chromatogram data in the Py-GCMS operating mode and pyrograms for the EGA-MS operating mode. 9. A method for analyzing the content of the mass fraction of free hydrocarbons and hydrocarbons pyrolysis in samples of oil-bearing rocks using a complex according to any one of paragraphs. 1-8, in which the analysis is carried out in an automatic mode, selected from the EGA-MS mode with a predetermined pyrolysis temperature range and the study of samples in the MSD, and the pyrolytic gas chromatography (PY-GC / MS) mode for the analysis of HC types in each of the temperature zones thermal desorption and pyrolysis.

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