Geology, geography and global energy

Scientific and Technical Journal

Geoecological and Hydrogeological Studies of the Caspian Sea and Oil and Gas Extraction from Its Waters

2012. №4, pp. 106-121

Serebryakov Andrey O. - Senior Lecturer, Astrakhan State University, 20a Tatishchev st., Astrakhan, Russian Federation, 414000,

Serebryakov Valentina I. - Senior Lecturer, Astrakhan Institute of Construction and Engineering, 18 Tatishchev st., Astrakhan, Russian Federation, 414056,

Serebryakov Aleksey O. - D.Sc. in Geology and Mineralogy, Professor,  Astrakhan State University, 20a Tatishchev st., Astrakhan, Russian Federation, 414000,

Serebryakov Oleg I. - D.Sc. in Geology and Mineralogy, Professor, Astrakhan State University, 20a Tatishchev st., Astrakhan, Russian Federation, 414000,

The article discusses marine and reservoir waters containing new oil and gas deposits in the northern Caspian Sea, covering their specific properties and compositions, and comparing them to other deep-water fields. Faced with declining commodities of extracted and processed oil and gas deposits in the Caspian, the study raises the possibility of recycling the water as a potential source of other raw materials. At this stage, the critique turns its focus to the actual waters of the Caspian Sea. It relates that they have a dynamic viscosity of 0,49-0,52 mPa/second resistivity for 0.045 Ohm/meter, and are filled with unsaturated gases. The gas saturation ratio stands at 0,9 in plantar waters, decreasing as their distance from the reservoir grows to background levels of 0,2–0,3. Furthermore, the standard content of gas separation in the waters is less than 1,53 m3/tonne, while the volume ratio of water (under reservoir conditions) reaches 1,015 m3/m3. The gas saturation ratio of water increases with depth. A distinctive feature of the water producing horizon is its high content of iodine (up to 15 mg/d3 ) and bromine (up to 150 mg/ d3 ), plus its changing ratios of dissolved components, depending on distance from the producing reservoir. In parallel, the document has examined the compatibility of marine waters from the perspective of productive horizons, finding they have a ratio of 9:1-1:9. It has also confirmed the lack of rainfall in the mixtures that can be recommended for sea water injection to maintain reservoir pressure. To increase the volume of oil extraction, without flooding the productive reservoirs, the blueprint recommends some ground water dynamics. These aim, inter alia, to control the proportion of water in the output, assess the potential extent of productive deposits, raise the capacity for oil recovery and identify annular pressure. With respect to oil recovery, the research paper has provided criteria for evaluating the hydrocarbon commodity in offshore exploration areas. In conclusion, the research paper has noted that the saturated gas pressures of formation waters range from 10,1–14,3 MPa, i.e. are lower than reservoir pressures.

Key words: reservoir,sea water,technology,composition,gas content,processing,injection