Principles of the assessment of the bottom environment pollution of on mastered oil and gas fields Печать E-mail


The problem of oil-and-gas fields mining on the Western-Arctic shelf turns from theoretical in practical now. In the near future of such fields involved in sphere of a practical mining of an oil-and-gas condensate, the field “Prirazlomnoe” will be first from. Multiple ecological investigations in the Pechora sea attempted both organizations MNR RF and ROSHYDROMET, and the academic organizations, and first of all MMBI testify that natural environment in these areas is not practically disturbed as a result of the conducted explorations, which one besides were completed more than 10 years ago.

In too time the geographic and geologic position of new oil-and-gas fields on western-arctic shelf is rather difficult from the point of view of their ecological safety. Arctic environment is very susceptible to various anthropogenous event. The severe climatic conditions, including multimonthly ice-reinforced cover and presence of icebergs in summer concern to such complicating exploitation of fields to the factors. The geological pattern of the majority of fields is characterized by presence of a lump of tectonic disturbances, which one play a double role. On the one hand they testify to modern geodynamic processes, continuing down to the present time, on the other hand upset sedimentary cover, resulting as to an infiltration natural hydrocarbons, and creating a possibility of breakthrough them during of wells operation. Speaking about modem geodynamics of oil-and-gas fields, we mean, first of all, newest tectonic motions, which one can are exhibited as earthquakes, and also vertical little gradient motions on zones tectonic of stresses. These processes can appear the destructive influencing on stability and integrity of drilling platforms, underwater oil-gas pipelines, also of other engineering facilities, major of which one are the transport terminals with bull storehouses miscellaneous, including dangerous for an environment.

Organization of effective control service on preservation of the environment on new oil-and-gas fields is in essence relevant, a task which one is not only prevention of crisis situations, but also forecasting their consequences. Negative affecting these events is not restricted to license leases, and appear much more widely. It harms first of all to littoral areas, and also, according to principles of natural sedimentation, to zones of an active clay sedimentation. As hydrocarbons are active sorbents, it may result in to occurrence of concentration various toxicants, which one are not connected immediately to processes of operation of wells, and radius of pollution extent may reach many tens kilometers. Therefore on start of economic assimilation of oil-and-gas fields it is the extremely important to determine principles of an estimation of negative their affecting on natural, including geologic, environment. It is: networks of observations, the nomenclature of measurements, their validity and periodicity. We also want to esteem these questions in the given report, basing as on experience of conducting of Federal monitoring in Barents Sea, since 1999 and materials of other Russian and Norwegian contributors having practical experience in this sphere.

Now it is possible to count resolved a question, which the most effective form of organization of regular supervisions by environment in zones of economic assimilation of a shelf is monitoring. Not pressing in terminology of this definition, we shall specify, that it means conducting periodic observations and measurements of various parameters of natural environment under strictly defined method with a choice of the determined investigation objects. The last is important, as any kind of overseeing by natural environment now may not cover all natural and anthropogenous factors accompanying a defined kind of economic activities. The choice of measured parameters should be dictated by their significance for estimation of condition of environment and an opportunity of their usage as indicators of pollution or failure of its condition.

As is known, "natureusers" according to license agreements conducts on license lease a self-supporting complex of ecological observations, results that one further are transferred in federal centre. At operation of oil-and-gas fields to risk factors of explorations (disturbance of sediment cover and communities of benthos organisms at an intrusion of drill columns in a marine bottom; raise of a muddiness of water near of drilling platforms because of affecting nontoxic drill fluids; waste in water of hydrocarbons both at operation of platforms, and at emergency oil blowouts at opening productive reservoirs) are added: acoustic effect of permanent drilling platforms, chemical pollution of an water thickness and bottom deposits-roiling of sediments at movement of vessels, change of a relief and such as bottom deposits at hydraulic engineering building. Last factors are shown especially within a contour of a mining of a useful mineral. Therefore them it is expedient to include only in structure of the "miningusers" monitoring. Occurrence in water of hydrocarbons results in chemical pollution not only water mass, but also bottom deposits. Contour of this pollution as we already pointed above, at all is not limited to counters of a license lease. Besides chemical pollution immediately may have an effect for biota factors, first of all a benthos, and through it fishes, the area of changes which one may cover vast water areas, allowing for migratory opportunities of biological entities. Thereof, chemical pollution should be determinate not only "miningusers" (that is practically impossible within the limits of all oil-and-gas province), but also federal sendee of monitoring, which one besides should carry audit functions in relation to the data presented private mining companies. Thus, in databases of federal services of monitoring, which one conduct subdivisions of Federal Hydrometeorology and Environmental Monitoring Sendee and MNR the Russian Federation, items of information as on license leases, and on territory of all oil-and-gas province, including potentially dangerous zones of haul of mineral oil annually should be assembled. Thus in a zone of liability of federal services get not only concrete sources of failure of environment, but also not less dangerous zones of possible pollutants accumulation, conterminous with zones of intensive accumulation of clay sediments. Thus all these data should concentrate in informational - analytical bases of a federal level that should provide their accessibility to various users. It does not happen, even on an example of the geologic data, with information bases of private mining companies because of various interpretation of the term "commercial secret". Only in this case there is a real base for an objective estimation of condition of natural environment and its dynamics under affecting of oil-and-gas objects. Clearly, that all told -business of the future, but they already today should be embodied in activity of the authority, from which one the Ministry of natural resources of the Russian Federation is leading under the status.

At definition of the nomenclature of observations and measurements we should have in view of two directions of investigations. First from them is connected with pollution of environment and encloses both a water strata, and the surface layers of bottom deposits, including one of the major natural geochemical barrier zones: 'bottom-water". Second direction are modem geodynamic processes, immunity of engineering structures under their effect and the forecast of development of the phenomena unfavorable or dangerous activity. These questions are included entirely into the competence of geologic sendee MNR of the Russian Federation, and realization of this constituent of monitoring of condition of entrails of a shelf is in an incipient phase, as in methodical, and the instrument relation.

At definition of exogenic pollution within the framework of geoenvironmental monitoring in a standard complex of observations there should be following types of measurements:

1. Express - analytical measurements onboard a vessel: near-bottom and pore waters - Eh, pH, electrical conductivity, a turbidity (only for near-bottom waters); bottom sediments - Eh:
2. Definition in near-bottom waters of heavy metals (Cd. Zn, Cu, Pb, Hg, As),
hydrocarbons (total), phenols;
3. Definition in pore waters of heavy metals (Cd, Zn3 Cu, Pb);
4. Definition in bottom deposits of heavy metals (Cd. Pb, Cu, Zn, Hg), hydrocarbons (total).

On occasion (at the moment of emergency floods of hydrocarbons etc.) or in specially stipulated cases it is expedient to determinate of hydrocarbons fractional composition for definition of their sources. As have shown the data of monitoring of the Barents Sea within the limits of oil-and-gas fields’ anomalous concentration of heavy metals in near-bottom waters frequently were fixed. The next years anomalies also were fixed, but is usually they changed a place. It was connected by us to display under rather thin sedimentary cover of outputs juvenile hydrocarbons. On the data aerial photographic survey in the Pechora Sea tracks of outpouring of mineral oil were established- which one had an endogenic genesis. Therefore the problem of difference natural and extracted hydrocarbons is sharp enough for the correct interpretation of total contents of hydrocarbons and estimation on this basis of technogenic component.

The problem of monitoring of endogenic processes is connected by that now sights about passive seismic of platforms are exposed to the increasing audit. In particular the north of the Archangelsk area large hydrocarbons reserves traced in shelf The majority of the detected structures, perspective on oil and gas as is connected with faults. The northwestern Barents Sea is located in a zone of concatenation of the Barents plate and the Baltic crystalline shield, which one is seismic practically on all its extent. Earthquakes have magnitudes 3-4 and separate reach 4.4 - 4.6. Four seismic events by force of 3.5-3.8 balls are registered in area of Karpinsky fault only in our century. On modern representations here it is possible to expect bumps intensity up to 7 balls. In eastern part of the Barents Sea three epicentres of earthquakes with magnitudes 4.3, 4.4 and 4.6 are fixed, and agree to prediction seismic maps here too it is possible to expect bumps up to 6-7 balls. The indirect data also testify for the benefit of development of modern geodynamic processes on the Western-Arctic shelf. The problem connected to considered modern movements, is encompass byed volume, that slow movements, as a whole practically secure for existence modern ecosystems, may have rather significant consequences at building hydraulic engineering structures, to which one pipe lines concern both drilling platforms with wells. Even rather gentle affecting of an anthropogenous loads together with gentle displays of geodynamics may call in geologic environment the inadequate appearance, considered in theories of catastrophes as failure of unstable equilibrium by a gentle signal. Thus development of the technogenic catastrophes, connected with breaking down of acting infrastructure of an oil-and-gas complex is possible. Therefore forecasting of such movements is the relevant problem at planning and realization of the measures connected to ecological safety of engineering structures.



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