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By Vladimir REZUNENKO, Cand. Sc. (Tech.), head of the Department of Long-term Development, Science and Ecology, ОАО GAZPROM; Vladimir YEREMIN, Dr. Sc. (Tech.), Director General, ZAO Federal R&D Center NefteGazAeroKosmos; Pavel FILIPPOV, Dr. Sc. (Phys. & Math.), laboratory head, Institute of the Energy Problems of Chemical Physics
The intensive use of natural gas, the purest fuel ecologically, has certainly played a crucial part in containing natural pollution. But there are signs that its Western Siberian reserves may be depleted soon. This compels the Gas Company GAZPROM to develop new pools farther north, particularly, in the shelf zone of the Kara and Barents Seas. The natural environment there is highly specific and very vulnerable. Consequently, steady control is needed over its conditions (ground sagging, modification of the plant kingdom, and so forth) during mining and stringing works. As a matter of fact, the entire gas supply system needs such control. Therefore the GAZPROM Company has come up with a program providing for a comprehensive system of aerospace servicing of the industry's enterprises.
The beginnings of this country's integrated gas supply system date back to the 1940s. Today it is a unique network comprising a variety of technologically interconnected subsystems: 290 fields, 225 compressor plants, and nearly 150 thousand km of gas mains. About 57 percent of these have been in service from 10 to 30 years, and 16 percent even longer than that. Their reliability reserve is as good used up. This means possible gas leakages and accidents. But the exploration and development of new pools situated mainly in the Far North is proceeding under harsh natural and climatic conditions that may have a negative effect on the performance of Russia's gas supply complex.
That is why the GAZPROM Company is setting up a monitoring system which takes in local and regional aerospace monitoring as well as data collection and evaluation centers for individual enterprises, regions and the industry as a whole.
We attach special importance to aerospace monitoring as the most promising and technologically advanced part of this system. Such kind of monitoring provides for surveys of the terrestrial surface and objects on it from artificial earth satellites, orbital stations and piloted spacecraft; and also from aircraft and helicopters carrying instruments to register the electromagnetic radiation of the terrestrial surface and objects (both self- and reflected radiation) in different spectral bands. Operating around the clock and in any weather, our aerospace monitoring system carries out high-resolution measurements (spatial, time and spectral resolution). Thereby we can get a complete picture of the gas pipeline networks and ambient environment.
The two component parts of aerospace monitoring (air- and spacecraft) are assigned specific jobs of their own. Say, aircraft and helicopters, if equipped with adequate instruments, can keep tabs on gas and oil pipelines, including the pipe geometry. These machines can thus assess the state of stress and deformation of piping, and detect gas and oil seepage or leakage. They can spot shallow underground lines and violations of depth standards. And last but not least, aircraft and helicopters can check on the state of pipe ballast and fastening devices, and pinpoint sections for intrapipe flaw detection.
As to the monitoring of the continental shelf (its configuration and depth), coastal lines and sea currents, of the ecological condition of sea-shelf zones, inland bodies of water and their evolution, round-the-clock and all-weather reconnaissance of the ice situation- this is the job of space-borne instruments. Orbital satellites watch sea vessels and other objects of GAZFLOT (Gas Fleet), they detect and monitor fires, floods and other emergencies. Space observations make it easier to estimate the risk and ecological consequences of such emergencies.
Yet in some areas both components of aerospace monitoring work in tandem. For instance, in determining soil saltiness, flooded or swamped sites, disturbances of permafrost in gas extraction districts and along pipelines. Map making is an important part of this work: drawing up new (and updating old) topographical maps of the scales 1:500,000 and 1:100,000 for laying and upgrading gas mains; compiling geological maps for mineral prospecting. Aircraft (helicopters) and orbital satellites enable more accurate assessments of the ecological conditions of fields, oil and gas transportation and processing (soil, water and atmospheric pollution, the process dynamics). Finally, both parts of aerospace monitoring perform another joint function in ascertaining the geological structure of oil-and-gas mining areas and in identifying anomalous geophysical factors of natural or technogenic nature responsible for landscape modification.
Even though this monitoring complex is still in its cradle, the experience gained by other countries in the development and use of prototype technology since the 1970s demonstrates its great possibilities. First, in rapid data collection and evaluation over vast areas, including remote regions and seas. Furthermore, this technology enables multiple measurements in areas otherwise off limits.
Most off the remote sounding techniques are based on the measurement of different parameters of the environmental electromagnetic radiation. In physical terms, two essential methods can be singled out, and these are studying the self-radiation of objects or the solar radiation reflected from them (what we call a passive method). Or we can illuminate a land tract with an artificial light source of definite spectrum and thus register reflected or diffuse beams of fluorescence (active method). In practice a very wide wavelength range is used- from waves in the centimeter band to gamma rays. As a result, there should be a large number of quite different observation apparatuses. The best ones are those employed for sounding in the microwave, infrared and visible bands.
Equipment employed on different wavelengths tackles different tasks. For instance, instruments in the visible spectrum, i.e. in the 0.4 to 0.7 Mm range, are used for cartography with a resolution of up to 15m and for bathymetry, or deep-sea sounding. They are applied for determining chlorophyll absorbency and the reserve of phytoplankton in seas and oceans; for assessing the growth potential of plants, and so forth. The database thus collected helps determine the presence of harmful substances in the biosphere. Detection and identification of oil spills certainly concerns us in the first place.
Studying objects in the infrared light has specific features of its own. The point is that the atmosphere does not let in waves of any length.
Laser/IR imaging complex on board the Mi-87 'copter.
But there are bands where such "penetration" is possible. These are what we call transparency bands (or windows of transparency if they are large enough) in which we are studying objects of interest to us. The 0.76 - 0.90Mm band is used for assessing the structure of plant life and its viability; shoreline maps are drawn in this band too. The 1.55 - 1.75um interval makes it possible to find the concentration of salt and moisture in soil, and map their occurrence. In addition, this band is good for terrain sounding through a thin cloud cover. The 2.08 - 2.35Mm band is used for determining the amount of the OH hydroxyl present in the atmosphere: OH has a dramatic effect on chemical processes there.
So much for transparency bands. As far as windows of transparency are concerned, we make use of three. The first one (3.0 - 5.0Mm) enables a full analysis of the atmosphere and detection of gas and condensate leakages (a large fraction of light hydrocarbons composed of propane, butane, pentane and hexane). Looking through this "window", we can "see" oil spills on land and water. The second window of transparency (8.0 to 12.0 Mm) allows to measure the amount of CO and CO 2 (carbon oxide and dioxide) as well as other harmful agents in the atmosphere impacting the planet's climate (hothouse effect). And last, the microwave band (0.9 mm to 1.5 cm) makes it possible to use radiometry for monitoring the humidity of the atmosphere as well as the concentration of carbon dioxide, methane, water, ammonia and other substances in it.
In passive observations the visible and infrared bands hold obvious advantages, namely in the high accuracy of temperature measurements and in high resolution compared with the microwave bands.
Now why should we measure thermal radiation of locality (temperature) and do it with high accuracy? We need do that in districts crossed by pipelines so as to be sure about their integrity or else find gas leekages, if any, and assess their intensity. In the Far North, we can thus determine the extent of earth freezing and trace an optimal route for a pipeline; and, if it has already been built, indicate sections of possible breakages.
As to microwave sounding, it brings more data on parameters of the atmosphere, topsoil, ice cover, precipitation zones and the like. Radio-frequency waves, which are absorbed, but are poorly dispersed in the clouds, with vegetation being transparent or semitransparent to them. These two factors facilitate studying soil and ground characteristics even in densely overgrown localities. In addition, radio waves can pierce the earth surface as deep as several meters, depending on the wavelength and on the radiophysical techniques used.
After monitoring in different frequency bands, we make a comparative study of aerospace images with the aid of different scanning devices; in many cases this makes it possible to avoid possible ambiguities in the process of interpretation of the optically inhomogeneous floor-water-atmosphere systems.
Space techniques are more efficient when we search for dangerous geodynamic processes occurring on a regional scale, or work to detect
Pipeline gas leakage spotted by a helicopter-borne IP imaging/television complex.
stresses and deformations of rock. Such techniques are quite good for ice situation monitoring, for forecasting of emergencies, for gas pipeline cartography and for finding petroliferous regions. Here are a few examples.
As it has been established in the course of aerospace, geological and geophysical investigations, today major tectonic disturbances in this country occur within petroliferous regions considered geodynamically quiet before. These are the West Siberian, Dnieper-Pripyat, Volga-Urals, Caspian and other oil-and-gas mining areas.
Exploring such rich oil-and-gas pools as Prirazlomnoye (Kara Sea), Bovanenkovo (Yamal Peninsula), Yamburg (the Ob Bay shore), Urengoi and others, we have discovered extensive zones of geological disturbances and active (progressive) faults, 0.5 - 07 km and 1.8 - 2.8 km wide. Both underground and surface outbursts of deposits, oil and gas including, are possible here to pollute subterranean, subsurface and surface waters. It is in such regions that soil and vegetation are impaired worst of all, and it is here that accidents in boreholes and on trunk and field pipelines are most frequent.
Nonstop monitoring is a must during well operations. The point is that the absence of anomalous physico-geological and geodynamic phenomena in the course of research and development does not guarantee the safe operation of oil and gas enterprises in the future. Quite the contrary, the intensive development of hydrocarbon deposits stimulates geodynamic, seismic and deformation processes within these areas because of the significant drop in pressure between oil or gas-bearing platforms; this may touch off tectonic shoves and emergency situations. It is very important to obtain high-quality aerospace photos of mining tracts. In our case, these can be zonal pictures of 1:2,600,000 to 1:5,000,000 that allow to get a 1:30 - 50 km map. Besides, such photographs make it possible to monitor natural and large technogenic objects in remote districts difficult of access (spectral bands 0.6 to 0.8 Mm) and do other jobs, such as fixing the features of streams, lakes and other bodies of water; spotting freshets, floods, underfloodings and the like (0.7 to 1.0Mm). Aerospace photography shows up surface water and ice cover contaminations (0.6 - 0.8 Mm), plant and soil modifications (0.5 - 0.8 Mm).
A comparative study of such shots allows to determine the configuration of land tracts modified by technogenic effects-say, areas where vegetation is burnt out; it enables us to fix ice-melting phases on bodies of water and their pollution. More than that, photography in the narrow spectral bands supplies information that makes it possible to identify and map tracts of soil thaws and under-flooded districts along communication lines, field and trunk gas pipelines among them.
Now let us turn to the "division of labor" between aircraft- and spacecraft-based technology, its present and future. Let's begin with aircraft.
Air-borne instruments handle the bulk of the local and regional monitoring of gas industry enterprises. Planes and helicopters make regular checks of gas pipelines in regions with a sparse network of roads; they detect gas and oil leakages. In addition, air-borne devices monitor the atmosphere for the presence of deleterious substances (like nitrogen oxides, carbon dioxide, hydrogen sulfide, and so on) in areas where hydrocarbons are mined, transported and processed.
Pollution control is carried out by standard methods of geochemical analysis. However, for reliable spotting of a pollution source (especially if pollution discharges are irregular), it is not enough to register the mere fact of pollution-it is likewise important to obtain a series of snapshot maps of a particular region at different moments and thus determine the pattern of pollution discharge spreading. Thereby localization of a pollution source will be facilitated.
To cope with all these tasks, we use air-borne units of laser sounding making it possible to obtain a three-dimensional map of an area as large as 100 km 2 within just one hour. Carrying out multiple overflights of petroliferous areas, it is possible to keep track of the shelf currents dynamics and learn the origin, evolution and dissipation (progress) of various anomalies and deviations of thermodynamic, geophysical and biological characteristics of the investigated zones. Besides, analytical laser spectroscopy enables remote assays of both oil concentration and grade.
Fluorescence spectroscopy, which makes it possible to identify a grade of petroleum product by its luminescence, is the main technique of air monitoring of iridescent oil films on water surface.
The use of lasers and radar does not require regular artificial illumination, a factor making air monitoring much easier. Such surveys allow to control large surface areas within a short time when no change of weather can take place. In addition, the narrow focusing of a laser beam enables radars to measure small horizontal waves, something that is quite impossible otherwise.
Laser-aided bathymetry (deep-sea sounding) of shelf zones is another line of air monitoring. The kit of instruments and devices now in use is much superior to older technology. For instance, subwater relief maps obtained with the help of innovative hardware cost only a sixth of the older bill, while the map-making speed is 100 times as high. And last, contemporary airborne laser systems, operating in the optimal blue- green region of the spectrum, can pierce sea water down to 150 meters and, given favorable conditions, as deep as 250 - 300 m, with a resolution in depth of 0.5 m. The thus collected data are very important for spotting gas leakages in underwater (submarine) pipelines, scours (gutters) underneath, shallow waters and other untoward phenomena.
Yet another trend in the air sounding of the marine surface is the use of the method of laser-assisted combined dispersion of water molecules. This technique is
predicated on the change of radiation wavelengths through interaction with water molecules. Thereby one can determine the temperature and salinity of sea water, measure the concentration of chemical impurities and dissolved oil in it, and find the composition of phyto-plankton. Its luminescence spectrum is much sensitive to changes of such environmental parameters as temperature and saltiness, and to the presence of microscopic quantities of active agents, dissolved gases, and so forth. So we can spot oil slicks on water and, what is more, get to know their thickness and composition.
Remote detection of natural gas leakages is of special significance. This involves the use of two types of units. The first one is represented by differential absorption lidars (laser infrared radars) whose radiation is characterized by two wavelengths (say, for methane 1=3.3912Mm, while 2 =3.392), with one wave absorbed by natural gas, and the other not. Both waves reach one point on the ground surface, and their reflection is registered by a photodetector on board. The methane concentration in the air is determined from the difference of their intensities. The Russian-made gas analyzer Efir-AK is one such unit. The other type, also developed on the laser basis, is Efir-K01 which measures the local concentration of methane along the air route.
Since Efir-AK is one of the most up-to-date systems, it merits a closer look. This is the brainchild of the Research Institute of the Gas Industry Economy and of the Institute of the Energy Problems of Chemical Physics (RAS). The gas analyzer operates on parametric light generators in which the wavelength of sounding radiation is changed smoothly in the 2.8 to 3.7Mm range which absorption lines for nearly all hydrocarbons including methane, ethane, propane and butane. Unlike its older counterparts, the Efir-AK gas analyzer works in a pulsed operation mode-in it the sounding radiation power attains 3 (10 5 - 10 6 ) W at pulse frequency up to 50 Hz. Carried aboard a helicopter, this gas analyzer allows to up the flight altitude to 150 - 500 m against 30 - 50 m, while the detectable rate of gas leakage is down to 0.3 m /h.
The Efir kit of instruments includes a receiver/transmitter unit for laser scanning of the atmosphere along and across the flight route. This makes it possible to get a two-dimensional picture of the concentration of impurities above multiple gas lines. And, what is also important, that can be done in one flight only. In addition, by using extra data on wind velocity and direction, and modern data-processing methods, we can track the methane dissipation profile and the emission source.
The Efir complex includes, over and above the gas analyzer, also infrared (IR) imaging and television systems, onboard computers and an orbital system for finding gas leakage coordinates. The IR imaging system supplies essential data on surface temperature contrasts due to gas throttling through a small
Typical heat anomalies on gas lines: a-underground leakages; b-cock (faucet) leakages; c-pipe goffer.
port. The TV system helps confine a gas pipeline route to reference points and identify heat anomalies, if any.
Even though the temperature contrast value above an underground gas leakage may reach 5 - 15C (port diameter 1 mm, pressure 50 - 60 atm) and it is reliably detected from a helicopter at altitude 250 m and velocity 100 km/h, background contrasts may exceed this value. Besides, it also depends on soil composition and humidity, wind force and other factors. Here we cannot do without a gas analyzer anyway.
And now let us take up the space sector of the aerospace monitoring system and consider its present state and its development prospects.
The start was made in the late 1980s and early 1990s as this country launched a series of Almai- Kosmos-1870* satellites equipped with synthetic aperture** radar. At the time this technology, in its technical characteristics, had no analogs elsewhere. But since our homemade systems have not been upgraded (and with the industry actually paralyzed), we have been compelled to use foreign analogs.
There are signs for the better though: after a protracted recession, our aerospace industry is picking up. The Federal Space Research Program envisages shifting, up until the year 2010, from the conventional "heavy" apparatuses to compact-size ones with just as high data collection characteristics that could cater to GAZPROM'S multifarious interests. It wants such things as panchromatic optimal resolution photos (to 1 - 2 m); multispectral high-resolution (3 - 5 m) and medi-
* See: V. Senkevich, "Russian Cosmonautics at the Turn of Two Centuries", Science in Russia, No. 1, 2001.- Ed.
** Aperture, here the radiation emitting or receiving surface of composite antennae.- Ed.
um-resolution (20 - 50 m) shots. All-important to us are what we call hyperspectral data with a resolution of 3 m. In this particular case you can get "at one go" as many as 1,000 snapshots in different spectral regions and obtain exhaustive information on the locality surveyed. And last, you get all-weather radar photos with a resolution of 1 to 100 m (corresponding to belt-of-view changes from one to many kilometers).
The novel trend-microsatellites for the remote sounding of the earth-is of essential interest to us. The S. A. Lavochkin R&D Association has made a feasibility study of a small, virtually miniature-size orbital platform with a mass of under 70 kg. In its data collection potential this platform will be not inferior to heavier counterparts, perhaps with the exception of detail-observation satellites only.
Microsatellites hold obvious advantages, for one, the low dataflow cost, which is a convenient arrangement for servicing the many regional consumers. Such satellites could be integrated in multiple space systems for attacking the priority tasks of the remote sounding of the earth. These include the monitoring of pipelines and related emergencies; the pinpointing of environmental pollution sites; the detection of fires and natural hydrometeorological phenomena on a regional and local scale.
But we shall not go into the Federal Space Research Program which, as we have just said, covers a period till 2010 and merits a special chapter. Here we would rather touch upon a space complex envisaged by this very program, a complex which gas industry workers are pinning high hopes on, and which they plan to put into service in 2005.
This Arkon-2, a system that is meant for nonstop detail observations of the terrestrial surface and for subsurface sounding regardless of illumination and weather conditions. Some of its characteristics: orbital altitude-550 - 600 km; orbital tilt-either 81.4 o or heliosyn-chronous; payload-1,320 kg; total mass of the space vehicle-4 tons; dataflow rate-15 - 600 Mbytes/s; service life, 7 years; power consumption by instruments - 8 kW; onboard memory-300 Gbytes.
The main unit aboard Arkon-2 for the remote sounding of the earth is a synthetic aperture-equipped three-frequency radar. It has all kinds of signal polarizers and onboard data processors. Depending on the mode of operation, this setup can make surveys on one of the three wavelengths: 3, 23 or 68 cm. Thus a radar snapshot of 10x10 km area with a resolution of 1 m will be obtained, or else 40, 50, 120, 400 or 450 km-wide belts of view will be fixed, with a resolution of 3 - 5; 5 - 8; 30; 30; and 50 m respectively.
Furthermore, the Arkon-2 kit is to include a high-resolution IR radiometer. It encompasses five spectral bands: 2.1 - 2.35; 3.5 - 4.0; 8.6 - 9.0; 10.6 - 11.2; 11.2 - 12.0 Mm with a spatial resolution in the nadir of 30 m. The belt of its view will make up 300 to 1,000 km with a temperature resolution of 0.1 - 0.15 K. Data collected by this system may be used for oil-and-gas prospecting and supplementary exploration, for determining optimal construction sites and routes of trunk pipelines. One of the basic functions of Arkon-2 will be to monitor the operating lines and oil-and- gas fields, spot potentially dangerous sites, assess the state of commercial objects and natural surroundings, and forecast their development prospects. Arkon-2 will also be capable of estimating the present scope of oil pollution and monitoring the ice situation in offshore oil-field development areas.
We have told you about aerospace monitoring, a technology that collects an immense body of useful information. Such information, however, should be processed and stored somewhere. This is the job of regional data-processing and storage centers which, in their turn, keep in touch with the state-run monitoring systems (at the RF Ministry for Emergency Situations, the Ekologia [Ecology] System at the RF Ministry for Natural Resources).
Computer-assisted geoinformation systems have now gained wide currency throughout the world. Such systems fix a body of monitoring data in real time and space. They include computerized facilities for data input, processing and representation (monitoring, cartographical and meteorological information). Relying on an extensive database, these systems contain physical and mathematical models for the analysis, diagnosis and prognosis of the climatic-ecological conditions of a concrete region. Here one of the most promising trends is represented by what we call the geological zoning of a territory, that is dividing it into sectors by identical values of one parameter only (say, concentration of pollutants, type of vegetation, soil and the like).
The GAZPROM Company is pushing ahead with the work on aerospace monitoring systems. Russian-made aircraft and helicopters, equipped with the remote-sounding- of-the-earth technology, can well rival their foreign counterparts and are even superior to them in some of the characteristics. We hope to get to the forefront in this field with the completion of the Federal Space Research Program.
Photos supplied by P. Filippov and V. Gridin.
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Vladimir REZUNENKO, Vladimir YEREMIN, Pavel FILIPPOV, AEROSPACE MONITORING FOR OIL AND GAS INDUSTRY // London: Libmonster (LIBMONSTER.COM). Updated: 07.09.2018. URL: https://libmonster.com/m/articles/view/AEROSPACE-MONITORING-FOR-OIL-AND-GAS-INDUSTRY (date of access: 23.04.2021).
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