Both water- and oil-base fracturing have been used in West Siberian wells. However, the vast majority of these wells are hydraulically fracture stimulated using water-base fracturing fluids because for the same job size, the base fluid for water-base jobs is much cheaper than that of oil-base jobs. However, in some situations oil-base fracturing fluid may be the only option to improve well production performance.

This paper reviews oil-base hydraulic fracturing case histories in Western Siberia. Such treatments were used in Jurassic formations because of formation water sensitivity and in Cretaceous formations to control fracture height. Oil-base fracture stimulation treatments were specifically designed with base fluid that had lower than usual viscosity while maintaining its ability to carry proppant and withstand the high asphaltene and water content of Siberian crude and reduce the risk of fracture extension into water zones.

In many cases post-treatment incremental production of oil-base jobs was better than that of water-base jobs. Switching to oil-base fracturing fluids led to control of fracture geometry and eliminated the problem of formation sensitivity to the fracturing fluid. Much lower water cuts were also achieved post oil-base treatments because of fracture height containment. Excluding the cost of base fluid, oil-base treatments saved the operator, on average, 35% of the job cost. This is mainly due to reducing job size and lowering water cut.

You can access this article if you purchase or spend a download.