Compared to West Siberia, Russia’s traditional oil production region, operators in East Siberia, which hasn’t been that well explored, have a harder time producing under complex geological conditions. Here, pay zones are often covered by volcanic rock and salt layers that complicate pinpointing of perspective areas, which justifies the need for new exploration methods. Factoring in these nuances, Russian operators in East Siberia tend to apply the latest seismic technology. A bright example is Gazprom Neft’s use of UniQ 3D seismic survey at the Chonsky group of fields. Schlumberger developed this technology in 2008 and it is currently implemented in the Chonsky project by GEOTEK Holding service company on the basis of a license agreement with the developer.
Three fields of the Chonsky group (operated by Gazpromneft Angara) are located on the border of the Irkutsk region and the province of Sakha (Yakutia). In 2005, the company obtained a license for Tympuchikanskoye field, in 2007 – for Ignyalinskoye and Vakunaiskoye fields. Their total hydrocarbon reserves are estimated at 125 million tons of oil and 225 billion cubic meters of natural gas.
In June 2012, Gazprom Neft invited Japan’s JOGMEC to jointly explore the Ignyalinsky block. The approved program included mapping out at least 450 square kilometers with 3D seismic surveys by the end of 2013, testing two already drilled wells and drilling two new wells. According to the agreement, JOGMEC was expected to provide the bulk of the $100 million investment in exploration. “Joint study of the Ignyalinsky block will help us better understand and assess productive potential of the field, and make necessary investment decisions in the future,” Gazprom Neft first deputy general director Vadim Yakovlev said at the time.
“Last year we started shooting on the Ignyalinsky block, and plan to continue this year. We applied standard 3D seismic technology using imported seismostations,” GEOTEК Holding chief geophysicist Vladislav Votsalevsky told OGE. According to Votsalevsky, Russian companies today most often use Sercel seismostations, though other manufacturers’ equipment – including local makes – is also present in the market albeit in a smaller proportion.
According to Votsalevsky, the Chonsky fields were previously surveyed mainly by 2D seismic, some profiles had been done in the years preceding the breakup of the Soviet Union and some are relatively recent. For East Siberia, 2D study suffices only for basic assessment, he adds. “Earlier, operators didn’t perform much 3D seismic in East Siberia as logistics and infrastructure were far worse than in West Siberia, but in recent years the situation has changed, this sector is now developing rapidly,” says Votsalevsky.
While standard seismic tech has performed rather well in West Siberia, its potential in the east has been fairly limited. Accordingly, drilling success rate in East Siberia is much lower than in West Siberia. Consequently, in order to obtain high accuracy data companies have to use more powerful exploration tools.