The article presents the path that the Zarubezhneft Company has taken to introduce multistage hydraulic fracturing technology at its fields, starting from pilot operations in vertical wells to conventional multistage workovers. The advancements in multistage hydraulic fracturing technology takes place in 2 general directions: proppant hydraulic fracturing in mixed lithology reservoirs and acid-proppant hydraulic fracturing in carbonate reservoirs. Carbonate reservoir D3-III is characterized by high stresses. Therefore, the general issue was to reduce the pressures and risks associated with this. Large diameter tubings and swellable packers with extended length were used to reduce the risk of leaks and damage of the completion system. The second challenge during hydraulic fracturing in the D3-III formation was to create a sufficient fracture width. It was resolved by modifying fracturing injection schedule. In Artinskian reservoir, hydraulic fracturing was associated with the risk of fracture propagation toward water-bearing layer. Low-tonnage hydraulic fracturing injections were used due to small thickness of barrier between the oil-bearing and water-bearing formations. Additional attention was paid for choosing the perforation system. Slotted perforation allowed to reduce the risk of cement breaking and behind casing flow. In addition, all hydraulic fracturing operations were monitored in real time. Basing on pressure-rate behavior, proppant injection stages were modified or even completely rejected. A pragmatic approach was used while implementation of hydraulic fracturing. The main solutions were verified on single-stage operations in vertical wells, and then customized for horizontal wells. For the purpose of fracturing operations improvement, it was supported by a set of surveys and studies. The described approach allows to achieve planned targets at all the wells and to start oil production from the objects that previously were considered as unprofitable.
