In the last two decades, hydraulic fracturing has become a routine completion practice in most oilfields producing from the low- and medium-permeability Jurassic formations in western Siberia. To optimize hydraulic fracture conductivity, operators and service companies were progressively decreasing polymer loading in fracturing fluids, developing new polymer-free fluids, implementing foams as fracturing fluids, increasing proppant size and concentration, enhancing polymer breaker performance, increasing breaker concentration, and implementing the tip screenout technique. All these methods have some positive impact on proppant pack conductivity but lead to higher risk of premature screenout. The intrinsic limitations stem from the fact that conductivity is created by the proppant pack, which physically limits permeability. The new channel fracturing technique allows development of an open network of flow channels within the proppant pack; thus, the fracture conductivity is enabled by such channels rather than by flow through the pores between proppant grains in the proppant pack. The channel fracturing technique is capable of increasing fracture conductivity by up to two orders of magnitude.
Talinskoe field, located near Nyagan, Russia, produces from a series of Jurassic sublayers at depths of 2270 to 2700 m. Several oil-saturated sandstone sublayers are separated by shale barriers, and their development is conducted separately. For some wells, production from bottom sublayers JK10 and JK11 became uneconomical due to injection water breakthrough or low liquid rates. Production in these wells was switched to upper layers JK2 through JK9 after perforation and stimulation operations. Five of these wells were stimulated with the channel fracturing technique. Six-month of post-frac production data were compared with production data from eight offset wells stimulated recently via conventional hydraulic fracturing. The wells stimulated with the channel fracturing technology showed an average productivity index about 51% higher. This production effect still remains positive. The absence of screenouts confirmed reliability in proppant placement observed in other projects worldwide.
The successful implementation of the channel fracturing technique in brownfield development is described in detail with a theoretical and operational review, results from laboratory experiments, and analysis of the production results in comparison with conventional fracturing.