RU2634488C1 - Method of remote searching indicator substances of oil-gas hydrocarbons - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: surface to be examined is scanned by means of a solid-state laser (1) mounted on the carrier, radiating in one beam synchronously or with tuning on three discrete generation wavelengths in the infrared, visible and ultraviolet regions of the spectrum. The signals at anti-Stokes frequencies in Raman scattering are received and processed. According to the obtained measurements, the quantitative and qualitative composition of the specified indicator substances of hydrocarbon gases that are fixed according to their spectra incorporated into the database of the computer processing program, is selected and determined. The spectral image is differentiated from the specified indicator substances. The obtained and processed data are displayed in the form of maps of indicator substance halo distribution with allocation of spatial anomalous zones.

EFFECT: expanding the functionality, increasing the reliability of search.

2 cl, 1 dwg

Description

The invention relates to the field of geophysics and can be used to search for oil and gas fields, as well as for geoecological monitoring in order to detect leaks in oil and gas pipelines.

The inventive method is applicable both for the study of territories, and for the study of marine water areas, because of this, in some cases, a generalization is used - the underlying surface (land, water area, the bottom of the water area). Unless otherwise specified, the term “surface layer of the atmosphere” extends to the layer of the atmosphere above the water surface.

Remote and, in particular, optical methods for chemical analysis of gaseous media are very promising for the search for mineral deposits, they are able to solve problems that are not available for classical search methods.

The prior art method for remote search for new oil and gas fields [Patent for the invention RU 2498358, publ. 11/10/2013]. The method is based on remote optical gas analysis using a lidar. In the process of gas analysis, a test surface is scanned with a laser beam, a spectral image of a set of chemical components in the surface layer of the atmosphere is formed, and spatial spectral image of the area is selected by specified indicator substances. Next, the registered gas components are compared with the composition of the reference mixture of hydrocarbon components corresponding to the geographical position of the terrain and the field, terrain mapping is performed with spatial differentiation according to the relief of the obtained spectral image of the probed terrain, and areas of reliable hydrocarbon occurrence are selected on the spectral image map. Unfortunately, the conditions and parameters of laser sensing are not disclosed in the patent description, however, it is said that this is one of the components of a comprehensive study, which also includes geological surveying and seismic surveying. In the description of the patent it is indicated that the described laser survey is a study prior to ground surveys (seismic), or can be used to reject traps identified as a result of seismic surveys.

A known method for the remote quantitative detection of fluid leaks in a pipeline of natural gas or oil, described in the patent - RU 2362986, publ. 07/27/2009, based on the use of two or more lasers of different wavelengths installed on one onboard platform. Also in the patent there is an indication that the method can be used for exploration of oil / gas and other natural resources. The laser scanning described in the patent is implemented according to the principle of differential absorption. The use of several lasers in the scanning system complicates the sensing of the underlying surface on inclined paths and, in general, the control system for them, leads to a time-consuming process of registration and recognition of detected substances in an amount of more than one, and virtually eliminates the express analysis of a multicomponent medium. To detect even a small group of indicator substances, reconfiguration is required during the measurement process. All this makes the technology described in patent RU2362986 ineffective for prospecting for oil and gas fields.

A similar system with several tunable lasers is described in patent RU 2411503, publ. 02/10/2011. The laser wavelengths correspond to the absorption lines of the substances being determined. Thus, for the detection and quantification of several indicator substances when implementing the method described in the patent, an appropriate number of lasers is required.

As a prototype, the method of airborne sounding of the atmosphere for the purpose of exploration of natural gas fields [Khabarov V.A. and Popov D.V. Airborne sounding of the atmosphere for the purpose of exploring natural gas deposits is a promising method for the automated search for gas deposits in the surface layer. - The journal "Engineering - from theory to practice." - Issue No. 1 (38) / 2015, published on the Internet: http://cyberleninka.ru/article/n/aviatsionnoe-zondirovanie-atmosfery-s-tselyu-razvedki-mestorozhdeniy-prirodnogo-gaza-kak-perspektivnyy-metod -avtomatizirovannogo # ixzz46AII4rW2]. The method described in the article is based on laser sensing of an atmospheric layer with registration of scattered reflection radiation by the surface. The method is implemented using two helium-neon lasers and an optical system. The use of the coincidence of the laser generation wavelength near 3.39 μm with the methane absorption line is justified by the fact that in this region there is no overlap of the absorption spectra of ordinary atmospheric gases. As a radiation source in the transmitting unit, two laser generators with amplifiers tuned to wavelengths λ ₁ = 3.3922 μm and λ ₂ = 3.3912 μm use output powers of 10 mW and 5 mW, respectively. Sounding is carried out by a sequence of alternating quasi-rectangular pulses at two wavelengths and differing in amplitude. The modulation frequency is 3400 Hz. Part of the radiation is used to synchronize the operation of the transceiver path.

One of the indicated wavelengths (λ ₁ ) coincides with the resonance absorption wavelength of methane, and the other (λ ₂ ), the reference one, is outside the spectrum of its absorption. A special requirement is to stabilize the wavelengths of the probe laser radiation during sensing and measurement. Comparison of two signals after recording the radiation collected by the receiving lens allows us to record only the fact of the presence of methane in the probed field along the optical path. This is not noted in the article, but for a specialist in this field, it is obvious that mapping with the use of a satellite navigation system is carried out simultaneously with laser measurements, but the distribution of concentrations on the surface is not displayed. At the same time, the sounding of the space is carried out only in one angular coordinate (for example, in the case of the aircraft platform, the underlying surface is probed in nadir), that is, without wide-angle scanning by laser radiation. The main disadvantage of the prototype is the need to use 2 lasers, and, accordingly, the use of a complex synchronization system. In addition, wide absorption bands by atmospheric water vapor and carbon dioxide do not allow the detection of components having intrinsic absorption bands in the same spectral ranges. The method described in the patent is suitable for recording only those substances whose absorption lines coincide with the wavelengths of the probe laser. A significant disadvantage of the prototype is associated with the impossibility of synchronous (simultaneous) registration of more than one gas component, which complicates the analysis of the composition of a multicomponent medium.

The basis of the invention is the task of expanding the arsenal of tools and creating a new method for remote search for indicator substances of the manifestations of oil and gas hydrocarbons, which, when probing with one laser, can simultaneously register a wide range of gases and directly measure the absolute values of the concentrations of chemicals without changing the composition and mode of the equipment. Achievable technical result - obtaining a spectral portrait of the underlying surface by identifying an array of chemicals, recording and measuring extremely low concentrations of identified indicators of hydrocarbon deposits (up to 10-20 billion ^-1 heavy hydrocarbons).

The problem is solved in that the claimed method of remote search for indicator substances of the manifestations of oil and gas hydrocarbons is based on the analysis of the composition of the medium above the underlying surface and is implemented using a laser hardware complex installed on board the carrier, for example an aircraft carrier. When analyzing the composition of the medium, the surface under study is scanned with a laser beam, anti-Stokes Raman scattering signals are received and processed, and the quantitative and qualitative composition of the specified indicator substances of hydrocarbon gases recorded by their spectra, which are stored in the database of the computer processing program, is determined and determined by the obtained measurements, and differentiate the spectral image according to the specified indicator substances. The obtained and processed data are displayed in the form of maps of the distribution of halos of indicator substances with the allocation of spatial anomalous zones. For scanning, a solid-state laser is used, emitting in one beam synchronously or with tuning at three discrete wavelengths of generation in the infrared, visible and ultraviolet regions of the spectrum.

In a preferred implementation, the scanning of the underlying surface is carried out in an angular field from -10 ° to + 10 ° with a single laser beam at the generation wavelengths: λ ₁ = 1047 nm, λ ₂ = 523.5 nm and λ ₃ = 261.7 nm, with a beam divergence of 1.0- 1.5 mrad in a pulse-periodic mode with a pulse duration of 10 ns with a pulse repetition rate of 200 Hz and a radiation energy P _λ for the mentioned generation wavelengths λ ₁ , λ ₂ , λ ₃ , respectively, mJ: P _λ1 = 150, P _λ2 = 70 and P _λ3 = 30.

The method is implemented as follows.

To capture the licensed area, an airplane or helicopter lidar is used, equipped with a GPS receiver, a device for determining the orientation of the aircraft carrier by the roll, pitch and yaw angles and an on-board computer for recording and processing information signals and navigation information linked to a single time scale. The software contains a database of spectra of indicator substances (VI) of manifestations of oil and gas hydrocarbons (from 5 to 20 VI - ethane, methane, propane, butane, other gases from a number of alkanes and their isomers), as well as atmospheric nitrogen. The flight altitude is from 100 to 5000 meters. Circling of the selected area is carried out on a grid of profiles.

The implementation of the method is illustrated by the figure, which shows a structural diagram of a hardware complex for laser scanning of oil and gas fields.

The figure indicates: 1 - a solid-state laser, 2 - a primary mirror, 3 - a secondary mirror in a telephoto lens, together 2 and 3 - an input telescopic lens, 4 - a polychromator, 5 - a mirror, 6 - an optical filter, 7 - a translucent plate, 8 - mirror system, 9 — detector, 10 — photodetector (based on a CCD), 11 — scanning mirror, 12 — firmware module.

The radiation of a solid-state laser 1 at three discrete wavelengths of the infrared, visible, and ultraviolet spectral ranges by a system of mirrors 8 is combined with the axis of the input telescopic objective 2, 3 of the receiving channel, hits a scanning mirror, and is directed to the probed area of the underlying surface. A part of the laser radiation is transmitted through a translucent plate 7 and a mirror 5 to the detector 9, which serves to control the laser radiation power and generates a synchronization pulse that starts the hardware-software module 12. The combination radiation scattered by the components of the underlying surface is focused by a telescopic lens 2, 3 through the filter 6 to the entrance slit of the polychromator 4. The spectral regions selected by the polychromator 4 corresponding to the anti-Stokes components of Raman scattering are recorded by a photodetector oystvom 10 and fed to the hardware and software module 12. The result of unit 12 is the identification of test substances manifestations petroleum hydrocarbons, calculation of the spatial distribution of the concentration of substances in the abnormal cloud and storage of data on the composition of a multicomponent geochemical environments in the investigated area.

For scanning, a solid-state laser is used that emits in one beam (along one optical axis) synchronously or with tuning at three discrete generation wavelengths in the infrared, visible and ultraviolet regions of the spectrum. In a preferred implementation, the scanning of the underlying surface is carried out in an angular field from -10 ° to + 10 ° at laser wavelengths: λ ₁ = 1047 nm, λ ₂ = 523.5 nm and λ ₃ = 261.7 nm, with a beam divergence of 1.0-1.5 mrad pulse-periodic mode with a pulse duration of 10 ns with a pulse repetition rate of 200 Hz and a radiation energy of P _λ for the mentioned generation wavelengths λ ₁ , λ ₂ , λ ₃ , respectively, mJ: P _λ1 = 150, P _λ2 = 70 and P _λ3 = 30.

.In the lidar apparatus complex operating by the Raman scattering method, the ratio of the lidar signal power from any indicator substance to its concentration is proportional to the ratio of the signal power from atmospheric nitrogen (N ₂ ) to its concentration, respectively. By measuring the signal power from nitrogen P _t corresponding to the known concentration N _t , as well as the signal power from the test substance P _s , determine its concentration according to the formula:

.

The search for indicator substances (VI) of a potential oil field was carried out on an area of 90 square meters. km using the remote search method based on the analysis of the medium on the underlying surface and were implemented using a laser instrument complex lidar mounted on board the MI-8 helicopter. Search survey was carried out according to a system of parallel profiles, laid in the sub-latitudinal direction, with a length of 10 km and a distance between profiles of 500 m. The altitude of flights on the working routes was determined by the terrain and ranged from 150 to 200 meters.

The analysis of the composition of a multicomponent medium on the underlying surface was carried out by scanning the laser beam for the following IWG IW: methane, ethane, propane and butane, the spectra of which were included in the base of the lidar instrument complex program. The underlying surface was scanned in an angular field from -10 ° to + 10 ° with a single laser beam at the generation wavelengths: λ ₁ = 1047 nm, λ ₂ = 523.5 nm and λ ₃ = 261.7 nm, with a beam divergence of 1.0-1.5 mrad pulse-periodic mode with a pulse duration of 10 ns with a pulse repetition rate of 200 Hz and radiation energy P _λ for the mentioned generation wavelengths λ ₁ , λ ₂ , λ ₃ , respectively, mJ: P _λ1 = 150, P _λ2 = 70 and P _λ3 = 30. To scan the search surface (the area of the search section), a solid-state laser was used that emits in one beam synchronously at three discrete generation wavelengths in the infrared, visible and ultraviolet regions of the spectrum. According to the flight data of the selected reference profile outside the territory of the search section, the average VI content was as follows for the selected hydrocarbon gases: methane - 0.070%, ethane - 0.037%, propane - 0.052% and butane - 0.020%. Accepted on the working routes, scanning signals of the search surface by lidar equipment were processed at anti-Stokes Raman frequencies. The data obtained were selected by the program for processing survey materials with the determination of the quantitative and qualitative composition of the given IWs, fixed by their spectra with simultaneous spectral differentiation. Based on the results of the selective processing of the obtained data on the composition and amount of IW in the automatic mode, maps of the aureoles of IW propagation were constructed with the identification of spatial anomalous zones exceeding the data of the reference profile by 5 times or more.

The anti-Stokes frequency shift of the scattered radiation corresponds to a change in the vibrational energy of the studied hydrocarbon molecule and does not depend on the spectral frequency of the exciting radiation. To determine the absolute concentration of registered substances and its spatial distribution, a normalized concentration of atmospheric nitrogen is used, information about which is included in the software.

The high efficiency of the proposed method is also manifested in the remote search for manifestations of oil and gas deposits in water areas, where the exposure from fluorescence of organic pollutants on the water surface and under water is significantly more powerful than atmospheric components, and the differential absorption method in the hydrosphere is not applicable at all, because infrared radiation is absorbed by water.

The search for indicator substances in water areas is carried out similarly as described above. When searching for indicator substances in water areas, the laser lidar complex can be installed on various types of media to work on the water surface (aero), on the surface of the water (any watercraft) and under water (for example, towing an underwater capsule on a cable to the boat) near the bottom. The search for IW in the waters of the coastal Arctic zones of the shelf, at depths of 20 to 50 meters, is carried out using a sea boat and the lidar equipment complex installed on its board. Laser scanning of the surface area of the water area with a total area of 50 square meters. km is carried out according to a system of parallel profiles, each five kilometers long, with a distance between the profiles of 500 meters oriented in the submeridian direction. The methodology for performing survey work on searching for IW in the water area and the parameters of the hardware settings and the program for processing incoming information were similar to the searches for IW on land, described in a detailed example. The purpose of the search surveys to search for OHM IH in the experimental section of the water area was to search for oil and gas deposits, the results of which revealed two areal anomalies of the dispersion halos of the VI - methane, ethylene and propane above the surface of the water area of the search section. The abnormal concentrations of the identified halos of the IW exceeded seven or more times the background values of the IW in the rest of the search area. When interpreting the materials obtained by scanning the search area of the water area for the content of IW UVG using the laser method, the following must be taken into account:

- the fact of a decrease in the concentration of the water-gas mixture in the marine environment with depth, incl. and methane;

- accumulation in the bottom layer and the creation of anomalies of hydrocarbon gases migrating from oil and gas deposits into water under favorable conditions;

- pressure, salinity, temperature;

- occurring sections of near-bottom ice in the Arctic seas and increased concentrations of hydrocarbon associated with them can be explained by the presence of gases in them in a crystalline hydrate state.

However, the sounding of water areas by laser radiation in these three spectral ranges is very specific due to the difference in the penetration depth of light with different wavelengths in sea water. In seawater, when moving from red to blue, the penetration depth of visible light grows from 11 to 160 m. Ultraviolet rays penetrate water even deeper, up to a maximum of 500-1000 m. Rays with a wavelength of 1.047 μm are reflected from the water surface, because . do not penetrate into water due to absorption [Popov NI, Fedorov KN, Orlov VM, Sea water: A reference guide. - M .: Nauka, 1979. - Data on the absorption of light and ultraviolet radiation in pure sea water]. IR wavelength (1.047 μm) is used only for hydrocarbon gases leaving the water column.

The same indicator gases can give different spectral responses under atmospheric conditions and when dissolved in the hydrosphere. When probing the hydrosphere, the spectral response of the Raman scattering of a water molecule, for which the value of the Stokes (anti-Stokes) shift is a reference, is usually chosen as the reference frequency.

By measuring the ratio of Stokes signals in three frequency octaves, you can get information about the manifestations of indicator substances at different depths relative to the water surface. From each of the three wavelengths at which the test medium is probed, a series of Stokes and anti-Stokes shifts (and corresponding wavelengths) will occur. Thus, for each laser wavelength, an octave of spectral wavelengths (frequencies) is obtained for various substances of a multicomponent medium.

At the same time, when probing the water area, it is obvious that the wavelength tuning can consist in overlapping the wavelength of 1.047 μm at the laser exit due to the absorption of infrared radiation by water.

Registration of anti-Stokes Raman frequencies ensures high noise immunity of the lidar hardware complex, since it allows protecting the receiving channel from the influence of fluorescence of substances under the influence of the same probing laser radiation.

Simultaneous sounding of the underlying surface (or water area) at wavelengths in the infrared, visible and ultraviolet ranges of the spectrum allows recording spectral displays in three frequency octaves, significantly increasing the array of detected substances in a multicomponent medium, increasing the reliability of the composition and spatial distributions of concentrations of indicator substances of hydrocarbon manifestations, and expanding range of exploration in various climatic and weather conditions, register to simulate spectral displays of echo signals already in three octaves of long waves. In addition, the synchronization of sounding at three wavelengths in the indicated spectral ranges makes it possible to level the effect of weather changes in time on the results of the operation of the laser hardware complex.

Claims (2)

1. The method of remote search for indicator substances of the manifestations of oil and gas hydrocarbons, characterized in that it is based on the analysis of the composition of the medium above the underlying surface and is implemented using a laser hardware complex installed on board the carrier, when analyzing the composition of a multicomponent medium, the surface under study is scanned with a laser beam, and process the signals at anti-Stokes Raman frequencies, select and determine if the received measurements the natural and qualitative composition of the specified indicator substances of hydrocarbon gases recorded by their spectra stored in the database of the computer program for processing, the spectral image is differentiated by the specified indicator substances, the obtained and processed data are displayed in the form of distribution maps of halos of indicator substances with the allocation of spatial anomalous zones, in this case, a solid-state laser is used for scanning, emitting in one beam synchronously or with three discrete tuning 's lasing wavelength in the infrared, visible, and ultraviolet regions of the spectrum. 2. The method according to claim 1, characterized in that the scanning of the underlying surface is carried out in an angular field from -10 ° to + 10 ° with a single laser beam at the generation wavelengths: λ ₁ = 1047 nm, λ ₂ = 523.5 nm and λ ₃ = 261.7 nm with a beam divergence of 1.0-1.5 mrad in a pulse-periodic mode with a pulse duration of 10 ns with a pulse repetition rate of 200 Hz and radiation energy P _λ , mJ, for the mentioned generation wavelengths λ ₁ , λ ₂ , λ _3, respectively: P _λ1 = 150, P _λ2 = 70 and P _λ3 = 30.

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