The majority of oil exploited from Russian oilfields today comes from the Volga-Urals and Western Siberian basin, where large-scale fracturing and coiled tubing operations have been on-going for the past six years. In the mainly brown fields, tertiary recovery methods such as water-flooding are implemented to maintain financial viability of the well stock. In many areas, however, production wells do not benefit enough from the water flood, or the injection scheme is not optimized.

A consequence of reservoir pressure depletion is the increase in filtrate leak-off of drilling, completion as well as stimulation fluids. The sensitivity of the formation to wellbore fluids, the impact of the wettability changes and near wellbore damage is not fully evaluated on all formations and fields. It is though evident that the volumes of wellbore fluids lost to the reservoir impact final productivity. It equally affects the possibility to flow the well back after stimulation treatment. Hydraulic fracturing treatments have become the most popular completion method in Russia, and foam-based fracturing fluids seems to be a possible solution to the above problems. Foam, though, has evaded application in the region until recently.

Absence of foam to this point is mostly due to equipment requirements and logistic complexity. A hydraulic fracturing treatment based on foam as the main proppant carrier fluid effectively reduces the amount of liquid pumped overall, provides better fluid-loss control and aids in post-treatment flowback. Foam fracturing causes less damage to the formation and proppant pack, therefore improving the productivity of the well.

A variety of reservoirs and the impact of foam fracturing is described and analyzed in this paper, from typical shallow gas to challenging deep oil reservoirs, using numerous fluid systems such as foamed visco-elastic surfactants to stable- and superfoams.

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