Ecological activities on the marine shelf

Ecological activities on the marine shelf

In connection with the steady growth of oil and gas production on the marine shelf, the improvement of the set of measures ensuring the protection of its biospheric functions and biological diversity becomes of particular importance.

One of the most important aspects of environmental protection is the extraction of oil and gas in strict compliance with the requirements for handling production and consumption wastes, improving the technology of neutralizing drilling wastes (DW), as well as a number of compensatory measuresrelated to environmental protection.

"Octopus" JSC within a frameworkofjoint work with "Lukoil-Nizhnevolzhskneft" LLC to improve the technology of purging of drilling waste generated during the construction of oil and gas wells on the Caspian Sea shelf conducted a number of laboratory and experimental studies. In the experiments we used DW samples taken fr om the oil fieldnamed after Yu. Korchagin with intervals of 120-751m and 2448-2457 m.

At the end of the process, solidified DW were tested for the following indices: compressive strength, bending strain, water-saturated strength, frost resistance, setting time.

The obtained results showed that solidifiedDWare classified as M100 grade in terms of strength, and F15 grade in terms of frost resistance (GOST 23558-94).

In addition to testing the solidified samples for strength, a laboratory analysis was carried out to determine their chemical composition.In accordance with GOST R 53241-2008 all analyzes were carried out in a five-fold water extract, conditioned for 7 days. At the heart of the extract was seawater, taken from the adjacent North Sea water area and previously studied for chemical composition. 

A comparative analysis of the chemical composition of DW and their derivative products showed that the safe material obtained by the purging method complies with the regulatory requirements (GOST 23558-94, SanPiN (sanitary regulations and standards) 2.1.7.1322-03) and can be used on the continental shelf for removal of the terrain relief,backfill of slag-free storage, as well as in the construction of insulating screens and the construction of roads.

As a compensatory measure related to environmental protection, it is proposed to use neutralized DW to create artificial reefs that are known to actively perform the function of the biofilter, restraining the sedimentatedoil particles and subjecting them to decomposition by microorganisms, and also create a detritus accumulation zone, a stable concentration of hydrobionts, their biodiversity and increased productivity.

"Octopus" JSC jointly with the specialists of the Caspian branch of the Institute of Oceanology named after P.P. Shirshov of RAS made samples of artificial reefs, which have the form of concrete cubes. Aneutralized drilling mud was added to the composition of one of them.

The staff of the Caspian branch of the Institute of Oceanology of the Russian Academy of Sciences in conjunction with specialists of “Octopus” JSCconductedobservations of the changes in the stateand quality of the marine environment in the areas of abandonment of developed wells in the Northern Caspian, wh ere they installed artificial reef modules. They showed that the fouling of all the samples was practically identical, regardless of their internal biological and chemical composition.

On the surface of the cubes, zoobenthos fouling was noted (zebra mussels andmytilasters ,balanus ) as well asphytobentospolysiphonia and enteromorpha algae.

Two articles were published on this subject: 

1. Ponomarenko D.V., Ushivtsev V.B., Yashchenko V.G. "Oil spills and protection of marine ecosystems by creating artificial reef fields"; 

2. Malinovskaya L.V., Ushivtsev V.B., Perevalov S.N., Ponomarenko D.V. "Proposals for the management of drilling waste in the development of marine fields."

Experience in carrying out environmental work on the marine shelf