MOSCOW — The French energy giant Total is in talks with Lukoil to form a joint venture to develop shale oil in Russia, as Moscow seeks to offset declining production from its conventional oil fields in Siberia.

The talks began before the Crimean crisis and are continuing, according to an oil company executive close to the negotiations who spoke only on the condition of anonymity. Lukoil and Total declined to comment on the project.

Lukoil, one of Russia’s largest oil companies, has a pilot drilling project in the massive, but so far unproductive, Bazhenov shale-rock oil deposit in Siberia, which by some estimates could be the largest reserve of shale oil in the world. Unlike conventional drilling, shale extraction involves forcing oil or gas from tight deposits of rock using new techniques like hydraulic fracturing, or fracking, which many environmentalists oppose.

The prospect of a Russian-French deal to develop shale oil in Siberia is noteworthy not only in the context of today’s geopolitical tension, or because of the importance of future oil output for Russia’s economy, but also because France’s resistance to fracking for environmental reasons means that Total would be doing in Russia what it cannot do on its home turf.