Scientific and practical approaches for environmental safety assurance in development of arctic shelf fields of Russia Печать E-mail


Russian economic dynamics is mostly affected by increasing of oil and gas production at shelf fields.

Russia has a great potential of offshore hydrocarbon deposits. Shelf initial resources may be evaluated as 76.4 billions m3 of gases (32 % of Russian total resources) and 15.1 billions tonnes of oil (14 % of the resources), including accumulated output and recoverable reserves. The most part of the hydrocarbons is positioned in Barents Sea and Kara Sea (arctic western shelf) and in Sea of Okhotsk (far-eastern shelf).

Nowadays over 40 oil and gas projects are being implemented at offshore fields of Russia.

Promotion of projects for shelf development requires huge investments, up-to-date equipment, availability of infrastructure and transport system, and development of the activities that ensure environmental safety while working.

At present Limited Liability Company (LLC) «Gasflot» is prospecting and exploiting gas fields on the shelf of Russia.
«Gasflot» has been prospecting and estimating the areas of Obskaya and Tazovskaya bays since 2000. During this time 8 prospecting wells have been drilled. It is while prospecting drilling the Severo-Kamennomysskoe field was discovered. The total gas resources of this field are estimated to 701 billions m3.

In view of particular vulnerability of Obskaya and Tazovskaya bays, the environmental solution to be the crucial task in development of the Severo-Kamennomysskoe field.

The core of the scientific approach for environmental safety assurance in development of the field is to define all factors that are able to affect the environment.

Investigation carried out as a part of integrated environmental monitoring at Obskaya and Tazovskaya bays while prospecting and evaluating in 2000-2004 (both in winter and summer), have disclosed the following main affecting factors:
- influence of physical fields:
- alteration of physical properties of the habitat:
- chemical influence by the substances;
- alteration of natural chemical parameters;
- disturbing of sea fauna of the drilling and production platforms.

Later the analysis of possible consequences and development of environmental safety management system must be done.

Environmental safety management system is to be effective at each stage of the field development project implementation, providing availability and execution of environmental safety activities. During implementation the strict control over the environment is necessary.

In case of possible failures, it is necessary to provide development, organization and logistics for contingency plans.

Water area of the Severo-Kamennomysskoe field is of particular attention in ecosystem of Obskaya and Tazovskaya bays. This area locates at the junction of Obskaya and Tazovskaya bays, and. therefore, unfavourable influence on this area causes maximum harmful effect on the environment of the water area. Consideration of these provisions and application of the above scientific approach led to encouragement of the philosophy of eco-safe development of the field.

The greatest influence on the environment is exerted while drilling the wells, hi view of this it is recommended to apply method of clusters drilling taking into account actual environmental conditions at the field; drilling time is to be as short as possible.

For production wells it is necessary to install BOP equipment to prevent oil and gas ingress.

The system providing re-injection of oil- and gas-bearing and produced water into the reservoir will be used. This enables to prevent erection of specific facilities for storage and handling of the sewage.

It is recommended to use water-based low-toxic drilling fluids.

This will prevent contaminants to enter the sea while sampling the well fluid.

At the Severo-Kamennomysskoe field the equipment providing tightness and completed with pneumatic transportation arrangement to be used for powder materials.

In addition, it is necessary to develop and approve contingency plans for any existing well and oil spillage contingency plan.

While arranging The Severo-Kamennomysskoe field, the activities providing further eco-safe operation to be executed; the activities have to include:

• availability of fire-boats and rescue vessels in the vicinity of critical works pertained to possible gas blowout; the vessel have to approach to the place of failure not later than fifteen minutes after the failure;
• provide gas explosion concentration control indicators and fire alarm indicators for the gas collecting, preparation and transportation facilities;
• routine and emergency ventilation for enclosed spaces of the gas collecting-preparation and transportation facilities.

In accordance with environmental requirements being in force, no production facility to exist on the seawater area after completion of work. To follow this requirement, the technical solutions providing eco-safe withdrawal of all facilities have to be developed at the further design stages.

The disposal method for drilling wastes is also an important problem in development of offshore fields. In terms of this problem, the two most possible disposal solutions that comply with environment safety requirements in the best way and are favourable for the Severo-Kamennomysskoe field arrangement, have been considered:

1) removal of drilling wastes onshore with further burial;

2) re-usage of the wastes (injection into the reservoir).

As a result of shortage of place for arrangement of necessary drilling waste containers on ice-resistant block conductors (that are to be installed at the Severo-Kamennomysskoe field) and on ice-resistant mobile drilling rig (drilling the wells), as well as due to leaks that are likely to occur during loading and transportation of containers, the re-usage of wastes (injection into the reservoir) proves to be the most efficient and eco-safe method for disposal of drilling wastes.

In addition, re-usage of the wastes (injection into the reservoir) has a number of benefits:

- In case of the Severo-Kamennomysskoe field arrangement, sludge injection may be the only procedure approved by supervising authorities.
- This is the only method providing the sludge disposal at the place of its formation.
- The area of the field arrangement is very sensitive in terms of ecology; in accordance with current environmental Russian and world requirements, sludge injection into the reservoir is the process that ensures the most environmental safety.

After consideration of these provisions, the re-usage of the wastes (injection into the reservoir) may be recommended as a base option for disposal of wastes while working at Obskaya bay.

While developing the offshore fields, it is important to monitor the environment permanently and note any alteration thereof in addition to activities preventing unfavourable influence on the ecosystem. For that purpose the optimal procedure of environmental monitoring at Obskaya bay has been considered and submitted.

In the events of simultaneous sewage blowout and other circumstances producing antropogenic influence on the water area, it is necessary to estimate the condition of water ecosystem urgently. For that purpose the short-time estimating methods to be applied.

Fluorescent method of analysis of algologic community of water areas is one of the possible ways of short-time environment estimation. Distribution of phytoplankton and its photosynthetic activity is to be determined basing on properties of pigments forming an algae.

Nowadays biological matter is widely used for determination of water quality. Bacterial luminescent system (bacteria are used for tests) is highly sensitive to affection of different substances (many of heavy metals, oil products, industrial poisons and other inhibitors of biological activity). This produced the base for development and practising the bioluminescent ecological tests using luminescent bacteria. Such eco-tests have the distinct advantage compared to other biotests: the result of this test is the integrated factor of the environment toxicity calculated during test time 5-30 minutes. This enables to test many samples, and, therefore, to explore vast water areas for presence of toxicants. The short-time feature enables to obtain immediate information to take safety measures.

Thus, the investigation carried out proves that works to be done will not exert unfavourable influence on ecosystem of Obskaya bay. provided LLC «Gasflot» follows the environmental safety philosophy and applies the most efficient and appropriate technical solutions in terms of ecology.



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